Your access to this publication has been provided by Learn More
Article
On-Demand Activatable Peroxidase-like Porous Silicon–Gold Nanozymes for Colorimetric Sensing
用于比色传感的按需活化过氧化物酶样多孔硅金纳米酶Click to copy article link
点击复制文章链接Article link copied!
点击复制文章链接Article link copied!
- Ayad SaeedAyad SaeedSchool of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, AustraliaMore by Ayad Saeed
- Srishti JainSrishti JainSchool of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, AustraliaMore by Srishti Jain
- Ganesh R. KokilGanesh R. KokilSchool of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, AustraliaAustralian Centre for Nanomedicine, University of New South Wales, Sydney, NSW 2052, AustraliaMore by Ganesh R. Kokil
- Mohammad B. GhasemianMohammad B. GhasemianSchool of Chemical Engineering, University of New South Wales, Sydney, NSW 2052, AustraliaSchool of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW 2006, AustraliaMore by Mohammad B. Ghasemian
- Astha SharmaAstha SharmaSchool of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, AustraliaMore by Astha Sharma
- Prakriti SiwakotiPrakriti SiwakotiSchool of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, AustraliaMore by Prakriti Siwakoti
- Kourosh Kalantar-Zadeh*Kourosh Kalantar-Zadeh*Email: kourosh.kalantarzadeh@sydney.edu.auSchool of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW 2006, AustraliaMore by Kourosh Kalantar-Zadeh
- Tushar Kumeria*Tushar Kumeria*Email: t.kumeria@unsw.edu.auSchool of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, AustraliaAustralian Centre for Nanomedicine, University of New South Wales, Sydney, NSW 2052, AustraliaMore by Tushar Kumeria
Abstract 摘要
Click to copy section link
点击复制章节链接Section link copied!
点击复制章节链接Section link copied!
Nanozymes have shown promise in a range of applications including food safety, environmental monitoring, clinical diagnostics, and bioimaging. However, more complex applications of nanozymes require better control over their catalytical properties. Herein, we report a peroxidase-like nanozyme that can be activated “on demand”. This is based on porous silicon (pSi) particles with nanosized gold inclusion, which are spontaneously generated on their surface by simple addition of a gold solution to a pSi particle suspension. The fast and spontaneous formation of gold nanoparticles (AuNPs) activates peroxidase-like nanozyme features. The nanozymes mimic the enzyme–cofactor relationship of natural enzymes with “on-demand” activation. The Michaelis–Menten constant and maximum velocity parameters were obtained as 1.92 mM and 0.37 × 10–8 MS–1 for tetramethylbenzidine and 0.70 mM and 0.55 × 10–8 MS–1 for H2O2, respectively. The activatable AuNP-pSi nanohybrid exhibited strong nanozyme activity with the ability to detect a thiol group-containing amino acid, homocysteine (Hcy), with a limit of detection of 0.30 μM. Our findings demonstrated that AuNP-pSi nanozymes can detect Hcy in complex solvents such as human serum efficiently. The AuNP-pSi nanozymes offer a robust stability profile without significant activity loss after 12 weeks of a storage period at room temperature. The AuNP-pSi nanozymes have potential in the development of colorimetric sensors and chemical industry processes that require enzymatic activity to switch on at specific parts of the reaction steps.
纳米酶在食品安全、环境监测、临床诊断和生物成像等一系列应用领域都大有可为。然而，纳米酶更复杂的应用需要更好地控制其催化特性。在此，我们报告了一种可 "按需 "激活的过氧化物酶样纳米酶。这种纳米酶基于带有纳米级金包合物的多孔硅（pSi）颗粒，只需在 pSi 颗粒悬浮液中加入金溶液，就能在其表面自发生成金包合物。金纳米粒子（AuNPs）的快速自发形成激活了过氧化物酶样纳米酶的特征。这种纳米酶模仿了天然酶的酶-因子关系，具有 "按需 "激活功能。四甲基联苯胺的迈克尔斯-门顿常数和最大速度参数分别为 1.92 mM 和 0.37 × 10-8 MS-1 ，四甲基联苯胺的迈克尔斯-门顿常数和最大速度参数分别为 0.70 mM 和 0.55 × 10-8 MS-1 分别为 H2O2 。可激活的 AuNP-pSi 纳米杂交表现出很强的纳米酶活性，能够检测含硫醇基的氨基酸高半胱氨酸（Hcy），检测限为 0.30 μM。我们的研究结果表明，AuNP-pSi 纳米酶能在人血清等复杂溶剂中高效检测 Hcy。AuNP-pSi 纳米酶具有良好的稳定性，在室温下储存 12 周后活性不会明显降低。AuNP-pSi 纳米酶具有开发比色传感器和化学工业过程的潜力，这些过程需要在反应步骤的特定部分开启酶活性。
This publication is licensed under the terms of your
institutional subscription.
Request reuse permissions.
本出版物根据您的机构订阅条款获得许可。申请重复使用权限。
Copyright © 2024 American Chemical Society
版权所有 © 2024 美国化学学会
版权所有 © 2024 美国化学学会
1. Introduction 1.导言
Click to copy section link
点击复制章节链接Section link copied!
点击复制章节链接Section link copied!
Enzymes are highly effective and selective biocatalysts. (1) They play a crucial role in sustaining life at the cellular level by catalyzing key biological reactions and extracting energy from energy-rich molecules, such as adenosine triphosphate (ATP). Besides their role at the cellular scale, due to their high substrate selectivity, enzymes have found many industrial applications such as those in sensing, (2) catalysis, (3) and pharmaceuticals. (4) However, industrial usage of enzymes is largely limited by their biological origin, which leads to narrow storage and usage conditions and high production cost, and renders them unstable under harsh environments. (5) To address these issues, an extended family of catalytic nanomaterials has emerged as synthetic enzymes, also known as nanozymes. (6) Yan and co-workers, in 2007, revealed that iron oxide nanoparticles exhibit inherent peroxidase-like activity. (7) Since then, many studies have investigated iron oxide and other materials for their enzyme-mimicking properties (8−10) including AuNPs. (11,12)
酶是高效且具有选择性的生物催化剂。(1) 它们通过催化关键的生物反应和从富含能量的分子（如三磷酸腺苷（ATP））中提取能量，在细胞水平上为维持生命发挥着至关重要的作用。除了在细胞层面的作用外，由于酶对底物具有高度选择性，因此在工业领域也有许多应用，如传感、(2)催化、(3)和制药。(4) 然而，酶的工业用途在很大程度上受到其生物来源的限制，这导致其储存和使用条件狭窄、生产成本高，并使其在恶劣环境下不稳定。(5) 为解决这些问题，催化纳米材料的一个大家族--合成酶（又称纳米酶）应运而生。(6) 2007 年，Yan 及其合作者发现氧化铁纳米粒子具有类似过氧化物酶的固有活性。(7) 此后，许多研究都对氧化铁和其他材料的酶模拟特性进行了研究 (8-10) 包括 AuNPs。(11,12) 。
酶是高效且具有选择性的生物催化剂。(1) 它们通过催化关键的生物反应和从富含能量的分子（如三磷酸腺苷（ATP））中提取能量，在细胞水平上为维持生命发挥着至关重要的作用。除了在细胞层面的作用外，由于酶对底物具有高度选择性，因此在工业领域也有许多应用，如传感、(2)催化、(3)和制药。(4) 然而，酶的工业用途在很大程度上受到其生物来源的限制，这导致其储存和使用条件狭窄、生产成本高，并使其在恶劣环境下不稳定。(5) 为解决这些问题，催化纳米材料的一个大家族--合成酶（又称纳米酶）应运而生。(6) 2007 年，Yan 及其合作者发现氧化铁纳米粒子具有类似过氧化物酶的固有活性。(7) 此后，许多研究都对氧化铁和其他材料的酶模拟特性进行了研究 (8-10) 包括 AuNPs。(11,12) 。
The most desirable feature of synthetic nanozymes is their ability to operate under harsh industrial conditions, in addition to their relatively low production cost and possible reusability. (13) Many such nanozymes offer durable enzymatic activity. However, most of the reported nanozymes offer no ability to control their activity like a number of natural enzymes (apozymes) that can modulate their activity including complete “turn-on” and “turn-off” in the presence or absence of specific small nonprotein compounds or metal ions known as cofactors. (14) In addition to modulating their activity, nature utilizes enzyme–cofactor interaction to preserve the activity of natural enzymes. Nanozymes, which tend to lose their activity over time, could potentially allow preservation of their activity over a longer storage period. Such precise control of the activation of enzymatic activity can accelerate the development of more intricate chemical processes comparable to the highly complex chemical processes necessary to sustain life. However, the nanozyme systems demonstrated thus far have not been able to offer such precise control over the enzymatic activity.
合成纳米酶最理想的特点是能够在苛刻的工业条件下工作，而且生产成本相对较低，还可以重复使用。(13) 许多此类纳米酶具有持久的酶活性。然而，大多数已报道的纳米酶无法像一些天然酶（apozymes）那样控制其活性，这些天然酶可以调节其活性，包括在特定的小型非蛋白化合物或称为辅助因子的金属离子存在或不存在的情况下完全 "开启 "和 "关闭"。(14) 除了调节酶的活性，自然界还利用酶与辅助因子的相互作用来保持天然酶的活性。纳米酶往往会随着时间的推移而失去活性，因此有可能在较长的储存期内保持其活性。这种对酶活性激活的精确控制可以加速发展更复杂的化学过程，堪比维持生命所必需的高度复杂的化学过程。然而，迄今为止展示的纳米酶系统还无法对酶活性进行如此精确的控制。
合成纳米酶最理想的特点是能够在苛刻的工业条件下工作，而且生产成本相对较低，还可以重复使用。(13) 许多此类纳米酶具有持久的酶活性。然而，大多数已报道的纳米酶无法像一些天然酶（apozymes）那样控制其活性，这些天然酶可以调节其活性，包括在特定的小型非蛋白化合物或称为辅助因子的金属离子存在或不存在的情况下完全 "开启 "和 "关闭"。(14) 除了调节酶的活性，自然界还利用酶与辅助因子的相互作用来保持天然酶的活性。纳米酶往往会随着时间的推移而失去活性，因此有可能在较长的储存期内保持其活性。这种对酶活性激活的精确控制可以加速发展更复杂的化学过程，堪比维持生命所必需的高度复杂的化学过程。然而，迄今为止展示的纳米酶系统还无法对酶活性进行如此精确的控制。
AuNPs have shown enzyme-mimicking abilities emulating peroxidase, catalase superoxide reductase, or dismutase. (15) In comparison to biological enzymes, AuNPs are excellent candidates for use in biochemical or medical research because of their straightforward synthesis, low cost, tunability, and biocompatibility. (11) AuNPs have also been demonstrated to possess high stability and rich surface chemistry, which enable facile conjugation techniques for biomolecules. (16,17) In comparison to other types of nanozymes, gold-based nanozymes are more popular due to their versatility as well as their attractive plasmonic and electrical properties. (11) The reduction of gold(III) derivatives with a citrate reducing agent, which was initially introduced by Turkevich in 1951, has been the primary approach for producing AuNPs for a considerable period. (18) Alternative methods for AuNP synthesis also exist, including the reduction of gold(III) through the use of different reducing agents such as hydrogen peroxide, gallic acid, and hydrazine. (19,20) However, the enzymatic activity of traditional AuNPs cannot be controlled to offer features such as on-demand activation like a natural enzyme-co-factor pair. Furthermore, the long-term storage of AuNPs remains a challenge due to particle aggregation and eventual decay in activity. (21) To overcome particle aggregation, decoration of AuNPs with functional moieties has become a proven method but surface modification may impede nanozyme activity as free access to AuNP surface is required to catalyze the substrates. (22,23) On-demand activatable nanozymes also have the potential to generate nanozymes that have an ultra-long-term stability. In addition, unlike functionalized nanozymes, the on-demand activatable nanozymes can maintain direct access of the substrate to the enzyme surface, while providing a greater control over the enzymatic reaction. This is like a number of natural enzymes that require cofactors (e.g., heme oxygenase, (24) methionine synthase, (25) and xanthine oxidase (26)) for activation or modulation of their enzymatic activity.
AuNPs 具有模拟过氧化物酶、过氧化氢酶、超氧化物还原酶或歧化酶的酶模拟能力。(15) 与生物酶相比，AuNPs 具有合成简单、成本低廉、可调节性强和生物相容性好等优点，是用于生化或医学研究的绝佳候选材料。(11) AuNPs 还被证明具有高稳定性和丰富的表面化学性质，可实现生物分子的简便连接技术。(16,17) 与其他类型的纳米酶相比，金基纳米酶因其多功能性以及诱人的等离子和电特性而更受欢迎。(11) 用柠檬酸盐还原剂还原金（III）衍生物的方法最初由 Turkevich 于 1951 年提出，在相当长的一段时间内一直是生产 AuNPs 的主要方法。(18) 还有其他合成 AuNP 的方法，包括使用过氧化氢、没食子酸和肼等不同还原剂还原金（III）。(19,20) 然而，传统 AuNPs 的酶活性无法控制，无法像天然酶-co 因子对那样提供按需激活等功能。此外，由于颗粒聚集和活性最终衰减，AuNPs 的长期储存仍然是一个挑战。(21) 为了克服颗粒聚集问题，用功能分子装饰 AuNPs 已成为一种行之有效的方法，但表面修饰可能会妨碍纳米酶的活性，因为 AuNPs 表面需要自由进入才能催化底物。 (22,23) 按需活化纳米酶还有可能产生具有超长期稳定性的纳米酶。此外，与功能化纳米酶不同，按需活化纳米酶可以保持底物与酶表面的直接接触，同时提供对酶反应的更大控制。这就像许多需要辅助因子（如血红素加氧酶、(24) 蛋氨酸合成酶、(25) 和黄嘌呤氧化酶(26) ）来激活或调节其酶活性的天然酶一样。
AuNPs 具有模拟过氧化物酶、过氧化氢酶、超氧化物还原酶或歧化酶的酶模拟能力。(15) 与生物酶相比，AuNPs 具有合成简单、成本低廉、可调节性强和生物相容性好等优点，是用于生化或医学研究的绝佳候选材料。(11) AuNPs 还被证明具有高稳定性和丰富的表面化学性质，可实现生物分子的简便连接技术。(16,17) 与其他类型的纳米酶相比，金基纳米酶因其多功能性以及诱人的等离子和电特性而更受欢迎。(11) 用柠檬酸盐还原剂还原金（III）衍生物的方法最初由 Turkevich 于 1951 年提出，在相当长的一段时间内一直是生产 AuNPs 的主要方法。(18) 还有其他合成 AuNP 的方法，包括使用过氧化氢、没食子酸和肼等不同还原剂还原金（III）。(19,20) 然而，传统 AuNPs 的酶活性无法控制，无法像天然酶-co 因子对那样提供按需激活等功能。此外，由于颗粒聚集和活性最终衰减，AuNPs 的长期储存仍然是一个挑战。(21) 为了克服颗粒聚集问题，用功能分子装饰 AuNPs 已成为一种行之有效的方法，但表面修饰可能会妨碍纳米酶的活性，因为 AuNPs 表面需要自由进入才能催化底物。 (22,23) 按需活化纳米酶还有可能产生具有超长期稳定性的纳米酶。此外，与功能化纳米酶不同，按需活化纳米酶可以保持底物与酶表面的直接接触，同时提供对酶反应的更大控制。这就像许多需要辅助因子（如血红素加氧酶、(24) 蛋氨酸合成酶、(25) 和黄嘌呤氧化酶(26) ）来激活或调节其酶活性的天然酶一样。
Electrochemically etched porous silicon (pSi) is known to possess interesting optical and redox properties. (27,28) The redox-active nature of pSi allows the generation of metal nanoparticles on its surface through fast and spontaneous reduction. (29) In the past, metallic nanostructures of various noble metals including silver, (29−33) palladium, (34−36) platinum, (37) nickel, (29,38) copper, (30,32,39) and gold (30,32,33,40,41) have been shown as such metal nanoparticle coatings. The metal nanostructures on pSi have predominantly been used in optical sensing as substrates for surface-enhanced Raman spectroscopy (SERS) (42,43) with limited examples of use as nanocatalysts (44−46) and drug delivery systems. (47,48) However, SERS-based sensing is expensive due to the requirement of sophisticated equipment as well as the time-consuming nature of the technique. We hypothesize that the spontaneous formation of metal nanoparticles in the presence of pSi presents an unrealized opportunity to develop nanozymes that can be activated when needed. This on-demand activatable nature is of particular interest for their long-term storage and in applications such as colorimetric sensing, where undesired nanoenzyme-catalyzed chemical reactions could be avoided to improve sensing performance.
电化学蚀刻多孔硅（pSi）具有有趣的光学和氧化还原特性。(27,28) 多孔硅具有氧化还原活性，可通过快速自发还原在其表面生成金属纳米颗粒。(29) 过去，各种贵金属的金属纳米结构包括银、(29-33) 钯、(34-36) 铂、(37) 镍、(29,38) 铜、(30,32,39) 和金(30,32,33,40,41) 已被展示为此类金属纳米粒子涂层。pSi 上的金属纳米结构主要用作表面增强拉曼光谱（SERS）(42,43) 的光学传感基底，也有少量用作纳米催化剂(44-46) 和药物输送系统的实例。(47,48) 然而，基于 SERS 的传感技术需要复杂的设备，而且耗时较长，因此价格昂贵。我们假设，在 pSi 存在下自发形成的金属纳米粒子为开发可在需要时激活的纳米酶提供了一个尚未实现的机会。这种按需激活的特性对于它们的长期储存和比色传感等应用特别有意义，因为在这些应用中，可以避免不希望发生的纳米酶催化化学反应，从而提高传感性能。
电化学蚀刻多孔硅（pSi）具有有趣的光学和氧化还原特性。(27,28) 多孔硅具有氧化还原活性，可通过快速自发还原在其表面生成金属纳米颗粒。(29) 过去，各种贵金属的金属纳米结构包括银、(29-33) 钯、(34-36) 铂、(37) 镍、(29,38) 铜、(30,32,39) 和金(30,32,33,40,41) 已被展示为此类金属纳米粒子涂层。pSi 上的金属纳米结构主要用作表面增强拉曼光谱（SERS）(42,43) 的光学传感基底，也有少量用作纳米催化剂(44-46) 和药物输送系统的实例。(47,48) 然而，基于 SERS 的传感技术需要复杂的设备，而且耗时较长，因此价格昂贵。我们假设，在 pSi 存在下自发形成的金属纳米粒子为开发可在需要时激活的纳米酶提供了一个尚未实现的机会。这种按需激活的特性对于它们的长期储存和比色传感等应用特别有意义，因为在这些应用中，可以避免不希望发生的纳米酶催化化学反应，从而提高传感性能。
In this work, the redox capabilities of pSi particles are exploited to spontaneously reduce ionic gold (Au3+) into metallic AuNPs onto their surface, forming a peroxidase enzyme-mimicking nanohybrid (AuNP-pSi). The AuNPs that are instantaneously deposited onto the pSi particle surface, to establish a nanohybrid, impart a peroxidase enzyme-mimicking activity (Figure 1). This is analogous to the activation of natural enzymes by a cofactor. The catalytic activity of the AuNP-pSi nanozymes is investigated by using the catalytic chromogenic reaction of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). Their selective peroxidase-like activity, thermal and long-term storage stability, and their use for colorimetric detection of a thiol-containing amino acid (homocysteine) is demonstrated in this work. The selectivity of AuNP-pSi nanozymes toward homocysteine is also examined by assessing their colorimetric sensing performance using a range of different amino acids.
在这项工作中，利用 pSi 粒子的氧化还原能力，将离子金（Au3+）自发还原成其表面的金属 AuNP，形成过氧化物酶模拟纳米杂化物（AuNP-pSi）。瞬时沉积到 pSi 粒子表面的 AuNPs 在建立纳米杂化作用的同时，也赋予了过氧化物酶模拟活性（图 1）。这类似于辅助因子激活天然酶。在过氧化氢（H2O2）存在下，利用 3,3,5,5- 四甲基联苯胺（TMB）的催化发色反应研究了 AuNP-pSi 纳米酶的催化活性。这项工作证明了它们的选择性过氧化物酶样活性、热稳定性和长期储存稳定性，以及它们在含硫醇氨基酸（同型半胱氨酸）比色检测中的应用。通过评估 AuNP-pSi 纳米酶对一系列不同氨基酸的比色传感性能，还考察了它们对同型半胱氨酸的选择性。
在这项工作中，利用 pSi 粒子的氧化还原能力，将离子金（Au3+）自发还原成其表面的金属 AuNP，形成过氧化物酶模拟纳米杂化物（AuNP-pSi）。瞬时沉积到 pSi 粒子表面的 AuNPs 在建立纳米杂化作用的同时，也赋予了过氧化物酶模拟活性（图 1）。这类似于辅助因子激活天然酶。在过氧化氢（H2O2）存在下，利用 3,3,5,5- 四甲基联苯胺（TMB）的催化发色反应研究了 AuNP-pSi 纳米酶的催化活性。这项工作证明了它们的选择性过氧化物酶样活性、热稳定性和长期储存稳定性，以及它们在含硫醇氨基酸（同型半胱氨酸）比色检测中的应用。通过评估 AuNP-pSi 纳米酶对一系列不同氨基酸的比色传感性能，还考察了它们对同型半胱氨酸的选择性。
Figure 1 图 1
Figure 1. Illustration of the peroxidase-mimicking activity of the on-demand activated AuNP-pSi nanozymes for the oxidation of TMB in the presence of H2O2 in a stepwise manner. pSi (light-yellow) was mixed with Au3+ solution to spontaneously produce AuNP-pSi (light-red), which shows a strong TMB oxidation capacity in the presence of H2O2 (blue).
图 1.按需活化的 AuNP-pSi 纳米酶在 H2O2 存在下逐步氧化 TMB 的过氧化物酶模拟活性说明。pSi （浅黄色）与 Au3+ 溶液混合后自发生成 AuNP-pSi（浅红色），它在 H2O2 （蓝色）存在下显示出很强的 TMB 氧化能力。
2. Experimental Section 2.实验部分
Click to copy section link
点击复制章节链接Section link copied!
点击复制章节链接Section link copied!
2.1. Materials 2.1.材料
Unless otherwise stated, all materials and chemicals were used as received without further purification. Single-side polished, highly boron-doped (p-type) monocrystalline silicon wafers (100) with less than 1 mΩ·cm in resistivity and ∼525 μm in thickness were purchased from Sil’tronix (France). Gold chloride (AuCl3), ACS-grade hydrofluoric acid (HF, 48% w/v in H2O), acetic acid, sodium acetate (NaCH3COO, ≥99%), hydrogen peroxide (H2O2, 30% w/w in H2O), 3,3′,5,5′-tetramethylbenzidine (TMB) ≥98.0%, d(+) glucose, l-ascorbic acid (AA), potassium hydroxide (KOH), sodium hydroxide (NaOH), dl homocysteine, l-aspartic acid, potassium salt, terephthalic acid (TA), absolute ethanol, and human serum were purchased from Sigma-Aldrich (Australia). Alanine, phenylalanine, leucine, and l-lysine hydrochloride were purchased from P3 Biosystems. Dimethyl sulfoxide (DMSO) and glycine were purchased from Chem-Supply, Australia. A 0.2 M sodium acetate buffer (NaOAc buffer) was prepared by dissolving sodium acetate solution in Milli-Q water and adjusting the pH with either acetic acid or NaOH. Milli-Q water with a resistivity of 18.2 MΩ·cm at 25 °C was used for all aqueous solutions used in this study.
除非另有说明，所有材料和化学品均按收到时的原样使用，无需进一步纯化。电阻率小于 1 mΩ-cm 且厚度为 ∼525 μm 的单面抛光高硼掺杂（p 型）单晶硅片（100）购自 Sil'tronix（法国）。氯化金（AuCl3）、ACS 级氢氟酸（HF，48% w/v in H2O）、醋酸、醋酸钠（NaCH3COO、≥99%）、过氧化氢（H2O2, 30% w/w in H2O ）、3,3′,5,5′-四甲基联苯胺（TMB）≥98.0%，d（+）葡萄糖，l抗坏血酸（AA），氢氧化钾（KOH），氢氧化钠（NaOH），dl同型半胱氨酸、l 天冬氨酸、钾盐、对苯二甲酸（TA）、绝对乙醇和人血清购自 Sigma-Aldrich（澳大利亚）。丙氨酸、苯丙氨酸、亮氨酸和l-赖氨酸盐酸盐购自 P3 Biosystems。二甲基亚砜（DMSO）和甘氨酸购自澳大利亚 Chem-Supply。0.2 兆醋酸钠缓冲液（NaOAc 缓冲液）的制备方法是将醋酸钠溶液溶于 Milli-Q 水，然后用醋酸或 NaOH 调节 pH 值。本研究中使用的所有水溶液均采用 25 °C 时电阻率为 18.2 MΩ-cm 的 Milli-Q 水。
除非另有说明，所有材料和化学品均按收到时的原样使用，无需进一步纯化。电阻率小于 1 mΩ-cm 且厚度为 ∼525 μm 的单面抛光高硼掺杂（p 型）单晶硅片（100）购自 Sil'tronix（法国）。氯化金（AuCl3）、ACS 级氢氟酸（HF，48% w/v in H2O）、醋酸、醋酸钠（NaCH3COO、≥99%）、过氧化氢（H2O2, 30% w/w in H2O ）、3,3′,5,5′-四甲基联苯胺（TMB）≥98.0%，d（+）葡萄糖，l抗坏血酸（AA），氢氧化钾（KOH），氢氧化钠（NaOH），dl同型半胱氨酸、l 天冬氨酸、钾盐、对苯二甲酸（TA）、绝对乙醇和人血清购自 Sigma-Aldrich（澳大利亚）。丙氨酸、苯丙氨酸、亮氨酸和l-赖氨酸盐酸盐购自 P3 Biosystems。二甲基亚砜（DMSO）和甘氨酸购自澳大利亚 Chem-Supply。0.2 兆醋酸钠缓冲液（NaOAc 缓冲液）的制备方法是将醋酸钠溶液溶于 Milli-Q 水，然后用醋酸或 NaOH 调节 pH 值。本研究中使用的所有水溶液均采用 25 °C 时电阻率为 18.2 MΩ-cm 的 Milli-Q 水。
2.2. Characterization and Instruments
2.2.表征和仪器
Transmission electron microscopic (TEM) imaging was performed using a JEOL 1400 transmission electron microscope at an accelerating voltage up to 120 kV (JEOL, Japan). The energy-dispersive X-ray spectroscopy (EDS) analysis was performed for elemental mapping using a JEOL JEM-F200 instrument with an electron acceleration energy of 200 kV (JEOL, Japan). The crystallographic analysis of both pSi and AuNP-pSi was carried out using a Phillips X’Pert Multipurpose X-ray diffractometer (XRD) (Almelo, The Netherlands) with Cu Kα radiation (λCu Kα = 1.5405 Å), 45 kV, 40 mA for 2θ values in the range 10–100°. Dynamic light scattering (DLS) assessments were conducted using a Litesizer 500 (Anton Paar, Australia). In this work, UV–vis spectra and TMB absorbance at 652 nm were acquired using a Multiskan Sky microplate spectrophotometer from Thermo Fisher Scientific, Australia. The fluorescence (FL) was measured by using a CLARIOstar Plus (BMG Labtech) plate reader.
使用加速电压高达 120 kV 的 JEOL 1400 透射电子显微镜（日本 JEOL 公司）进行透射电子显微镜（TEM）成像。使用电子加速能量为 200 kV 的 JEOL JEM-F200 仪器（JEOL，日本）进行了能量色散 X 射线光谱（EDS）分析，以绘制元素图谱。使用 Phillips X'Pert 多用途 X 射线衍射仪 (XRD)（荷兰 Almelo），在 Cu Kα 辐射（λCu Kα = 1.5405 Å）、45 kV、40 mA、2θ 值在 10-100° 范围内对 pSi 和 AuNP-pSi 进行了晶体学分析。使用 Litesizer 500（澳大利亚安东帕公司）进行了动态光散射（DLS）评估。在这项工作中，使用澳大利亚赛默飞世尔科技公司生产的 Multiskan Sky 微孔板分光光度计采集了紫外可见光谱和 652 纳米波长处的 TMB 吸光度。荧光（FL）通过 CLARIOstar Plus（BMG Labtech）平板阅读器测量。
使用加速电压高达 120 kV 的 JEOL 1400 透射电子显微镜（日本 JEOL 公司）进行透射电子显微镜（TEM）成像。使用电子加速能量为 200 kV 的 JEOL JEM-F200 仪器（JEOL，日本）进行了能量色散 X 射线光谱（EDS）分析，以绘制元素图谱。使用 Phillips X'Pert 多用途 X 射线衍射仪 (XRD)（荷兰 Almelo），在 Cu Kα 辐射（λCu Kα = 1.5405 Å）、45 kV、40 mA、2θ 值在 10-100° 范围内对 pSi 和 AuNP-pSi 进行了晶体学分析。使用 Litesizer 500（澳大利亚安东帕公司）进行了动态光散射（DLS）评估。在这项工作中，使用澳大利亚赛默飞世尔科技公司生产的 Multiskan Sky 微孔板分光光度计采集了紫外可见光谱和 652 纳米波长处的 TMB 吸光度。荧光（FL）通过 CLARIOstar Plus（BMG Labtech）平板阅读器测量。
2.3. Synthesis of AuNP-pSi Nanohybrids
2.3.AuNP-pSi 纳米杂化物的合成
Porous silicon was fabricated through the electrochemical etching method, wherein the porous layer was detached from the silicon substrate via the lift-off technique, transforming it into nanoparticles using sonication. Briefly, the monocrystalline silicon wafer was diced into squares of approximately 4 cm2 and packed in an electrochemical cell made from Teflon. The electrolyte is composed of 48% HF acid solution and ethanol (volume HF acid solution/volume ethanol = 3:1). A platinum wire served as the cathode electrode, while a silicon wafer served as the anode. First, a sacrificial layer was produced at an anodic current density of 100 mA/cm2 for 30 s, which was then removed with 2 M KOH. The porous layer was fabricated by applying alternating pulses of low and high current density (50 mA/cm2 for 1.8 s and 400 mA/cm2 for 0.36 s), respectively, which were repeated for 140 cycles. The porous silicon film was removed through electropolishing at a low current density of 3.7 mA/cm2 for 250 s in an electrolyte made of 1:29 (v:v) of 48% aqueous HF/ethanol. Following electropolishing, the resulting free-standing porous silicon layer was subjected to ultrasonication for 24 h to yield porous silicon nanoparticles. Particles of approximately 200 nm in size were collected by centrifuging away the larger particles for 5 min at 5000g and collecting the supernatant. The particles were kept in ethanol at room temperature (RT) as a stock solution with a concentration of 8 mg/mL. The AuNP-pSi nanohybrids were prepared by mixing desired volumes of the fabricated porous silicon nanoparticles (8 mg/mL) with AuCl3 (10 mM).
多孔硅是通过电化学蚀刻法制造的，其中多孔层是通过掀离技术从硅衬底上剥离的，利用超声波将其转化为纳米颗粒。简而言之，将单晶硅片切割成约 4 cm2 的正方形，然后装入由聚四氟乙烯制成的电化学电池中。电解液由 48% 的 HF 酸溶液和乙醇（体积 HF 酸溶液/体积乙醇 = 3:1）组成。铂丝作为阴极电极，硅片作为阳极。首先，以 100 mA/cm2 的阳极电流密度在 30 秒内生成牺牲层，然后用 2 M KOH 将其去除。通过交替施加低电流密度和高电流密度脉冲（分别为 50 mA/cm2 1.8 秒和 400 mA/cm2 0.36 秒）来制造多孔层，重复 140 个循环。在 1:29 (v:v) 的 48% 氢氟酸/乙醇水溶液中，以 3.7 mA/cm2 的低电流密度电解 250 秒，去除多孔硅膜。电抛光后，将得到的独立多孔硅层超声处理 24 小时，生成多孔硅纳米颗粒。在 5000的转速下离心 5 分钟并收集上清液，收集约 200 nm 大小的颗粒。颗粒在室温（RT）下保存在乙醇中，作为浓度为 8 mg/mL 的储备溶液。 将所需体积的多孔硅纳米粒子（8 mg/mL）与 AuCl3 (10 mM) 混合，制备出 AuNP-pSi 纳米混合体。
多孔硅是通过电化学蚀刻法制造的，其中多孔层是通过掀离技术从硅衬底上剥离的，利用超声波将其转化为纳米颗粒。简而言之，将单晶硅片切割成约 4 cm2 的正方形，然后装入由聚四氟乙烯制成的电化学电池中。电解液由 48% 的 HF 酸溶液和乙醇（体积 HF 酸溶液/体积乙醇 = 3:1）组成。铂丝作为阴极电极，硅片作为阳极。首先，以 100 mA/cm2 的阳极电流密度在 30 秒内生成牺牲层，然后用 2 M KOH 将其去除。通过交替施加低电流密度和高电流密度脉冲（分别为 50 mA/cm2 1.8 秒和 400 mA/cm2 0.36 秒）来制造多孔层，重复 140 个循环。在 1:29 (v:v) 的 48% 氢氟酸/乙醇水溶液中，以 3.7 mA/cm2 的低电流密度电解 250 秒，去除多孔硅膜。电抛光后，将得到的独立多孔硅层超声处理 24 小时，生成多孔硅纳米颗粒。在 5000的转速下离心 5 分钟并收集上清液，收集约 200 nm 大小的颗粒。颗粒在室温（RT）下保存在乙醇中，作为浓度为 8 mg/mL 的储备溶液。 将所需体积的多孔硅纳米粒子（8 mg/mL）与 AuCl3 (10 mM) 混合，制备出 AuNP-pSi 纳米混合体。
2.4. Peroxidase-Mimicking Activity of AuNP-pSi
2.4.AuNP-pSi 的过氧化物酶模拟活性
A series of optimization experiments were carried out to assess the peroxidase-like activity of AuNP-pSi. Optimal AuNP-pSi concentrations were explored through altering the ratio (v:v) of pSi (8 mg/mL) and gold salt solution (10 mM of AuCl3). The impact of pH on the enzyme-catalysis reaction was tuned through alterations of the pH of NaOAc buffer from 2.5 to 7.5. The working temperature effect was also studied at a broader range of temperatures, 25–45 °C. The thermal stability of the AuNP-pSi nanozyme was assessed in relation to natural horseradish peroxidase (HRP). The experimental procedure involved exposing both the AuNP-pSi nanohybrid and HRP to various temperatures (40, 60, 80, and 100 °C) for a duration of 45 min. Subsequently, TMB (1000 μM) and H2O2 (700 mM) were, respectively, added into the aforementioned reaction solutions followed by measuring the absorbance at 652 nm. An additional experiment was conducted to investigate the glucose oxidizing potential of the AuNP-pSi nanozyme. The experiment involved adding a solution containing 100 μM d-glucose to AuNP-pSi which then was incubated for 2 h. After 2 h, the activity was tested by addition of TMB (1000 μM) in NaOAc buffer. To assess the stability of the AuNP-pSi nanozyme, a series of peroxidase-like activity experiments were conducted on different days, ensuring that consistent conditions were maintained throughout the testing process. Typically, all peroxidase-like activity experiments for AuNP-pSi were conducted in the presence of 700 mM H2O2 and 1000 μM TMB dissolved in DMSO. The pH for these experiments was fixed at 3.5 during the activity optimization process except for the set of experiments aimed at assessing the effect of pH on the nanozymatic activity of AuNP-pSi nanohybrids. The formation of the blue charge-transfer complex (TMBox) was quantified by determining the absorbance at 652 nm after 30 min of incubation with TMB and H2O2.
为了评估 AuNP-pSi 的过氧化物酶样活性，我们进行了一系列优化实验。通过改变 pSi（8 mg/mL）和金盐溶液（10 mM 的 AuCl3）的比例（v:v），探索了 AuNP-pSi 的最佳浓度。通过改变 NaOAc 缓冲溶液的 pH 值（从 2.5 到 7.5），调整了 pH 值对酶催化反应的影响。此外，还在 25-45 °C 的更大温度范围内研究了工作温度的影响。结合天然辣根过氧化物酶（HRP）评估了 AuNP-pSi 纳米酶的热稳定性。实验过程包括将 AuNP-pSi 纳米杂交酶和 HRP 暴露在不同温度（40、60、80 和 100 °C）下 45 分钟。随后，在上述反应溶液中分别加入 TMB（1000 μM）和 H2O2 （700 mM），然后在 652 纳米波长处测量吸光度。为了研究 AuNP-pSi 纳米酶的葡萄糖氧化潜能，还进行了另一项实验。实验包括向 AuNP-pSi 中加入含有 100 μM d 葡萄糖的溶液，然后培养 2 小时。为了评估 AuNP-pSi 纳米酶的稳定性，在不同的日期进行了一系列过氧化物酶样活性实验，以确保在整个测试过程中保持一致的条件。通常，AuNP-pSi 的所有过氧化物酶样活性实验都是在 700 mM H2O2 和 1000 μM TMB 溶于 DMSO 的情况下进行的。这些实验的 pH 值固定为 3。在活性优化过程中，除了旨在评估 pH 值对 AuNP-pSi 纳米混合物的纳米酶活性的影响的一组实验外，其他实验的 pH 值均为 5。TMBox 与 H2O2 孵育 30 分钟后，通过测定 652 纳米波长处的吸光度来量化蓝色电荷转移复合物（TMBox ）的形成。
为了评估 AuNP-pSi 的过氧化物酶样活性，我们进行了一系列优化实验。通过改变 pSi（8 mg/mL）和金盐溶液（10 mM 的 AuCl3）的比例（v:v），探索了 AuNP-pSi 的最佳浓度。通过改变 NaOAc 缓冲溶液的 pH 值（从 2.5 到 7.5），调整了 pH 值对酶催化反应的影响。此外，还在 25-45 °C 的更大温度范围内研究了工作温度的影响。结合天然辣根过氧化物酶（HRP）评估了 AuNP-pSi 纳米酶的热稳定性。实验过程包括将 AuNP-pSi 纳米杂交酶和 HRP 暴露在不同温度（40、60、80 和 100 °C）下 45 分钟。随后，在上述反应溶液中分别加入 TMB（1000 μM）和 H2O2 （700 mM），然后在 652 纳米波长处测量吸光度。为了研究 AuNP-pSi 纳米酶的葡萄糖氧化潜能，还进行了另一项实验。实验包括向 AuNP-pSi 中加入含有 100 μM d 葡萄糖的溶液，然后培养 2 小时。为了评估 AuNP-pSi 纳米酶的稳定性，在不同的日期进行了一系列过氧化物酶样活性实验，以确保在整个测试过程中保持一致的条件。通常，AuNP-pSi 的所有过氧化物酶样活性实验都是在 700 mM H2O2 和 1000 μM TMB 溶于 DMSO 的情况下进行的。这些实验的 pH 值固定为 3。在活性优化过程中，除了旨在评估 pH 值对 AuNP-pSi 纳米混合物的纳米酶活性的影响的一组实验外，其他实验的 pH 值均为 5。TMBox 与 H2O2 孵育 30 分钟后，通过测定 652 纳米波长处的吸光度来量化蓝色电荷转移复合物（TMBox ）的形成。
2.5. Mechanism of the AuNP-pSi Nanozyme Activity
2.5.AuNP-pSi 纳米酶的活性机理
Two •OH radical scavengers, AA and TA, were used to investigate the mechanism of peroxidase-like activity of AuNP-pSi. According to a standard procedure, a certain amount of ascorbic acid (5 mM) was added into the AuNP-pSi nanohybrid solution containing 1000 μM TMB, and 700 mM H2O2 in the NaOAc buffer at pH 3.5. (49) The color intensity was monitored by both the naked eye and absorbance at 652 nm after 30 min. In the TA-based mechanism confirmation experiment, different amounts of AuNP-pSi, spanning from 0 to 160 μg, were added to a 300 μL solution of NaOAc buffer (pH 3.5) containing 10 μL of H2O2 and 10 μL of 0.2 M TA. Successively, the mixture was incubated in darkness for a duration of 12 h. (50) The fluorescence measurements were then carried out using a CLARIOstar Plus (BMG Labtech) plate reader at an excitation wavelength of 315 nm and an emission range from 400 to 560 nm.
研究人员利用AA和TA这两种-OH自由基清除剂来研究AuNP-pSi过氧化物酶样活性的机理。按照标准程序，在含有 1000 μM TMB 和 700 mM H2O2 的 AuNP-pSi 纳米杂交溶液（pH 值为 3.5）中加入一定量的抗坏血酸（5 mM）。(49) 30 分钟后用肉眼和 652 纳米吸光度监测颜色强度。在基于 TA 的机理确认实验中，将不同量的 AuNP-pSi 加入到 300 μL 的 NaOAc 缓冲溶液（pH 3.5）中，其中含有 10 μL 的 H2O2 和 10 μL 的 0.2 M TA。(50) 然后使用 CLARIOstar Plus（BMG Labtech）平板阅读器进行荧光测量，激发波长为 315 nm，发射范围为 400 至 560 nm。
研究人员利用AA和TA这两种-OH自由基清除剂来研究AuNP-pSi过氧化物酶样活性的机理。按照标准程序，在含有 1000 μM TMB 和 700 mM H2O2 的 AuNP-pSi 纳米杂交溶液（pH 值为 3.5）中加入一定量的抗坏血酸（5 mM）。(49) 30 分钟后用肉眼和 652 纳米吸光度监测颜色强度。在基于 TA 的机理确认实验中，将不同量的 AuNP-pSi 加入到 300 μL 的 NaOAc 缓冲溶液（pH 3.5）中，其中含有 10 μL 的 H2O2 和 10 μL 的 0.2 M TA。(50) 然后使用 CLARIOstar Plus（BMG Labtech）平板阅读器进行荧光测量，激发波长为 315 nm，发射范围为 400 至 560 nm。
2.6. Michaelis–Menten Kinetic Parameters
2.6.迈克尔斯-门顿动力学参数
The Michaelis–Menten kinetic parameters are expressed as the maximal rate of reaction (Vmax) and the Michaelis–Menten constant (Km). The steady-state kinetic experiments were conducted at 40 °C, utilizing 4 μL of pSi (8 mg/mL) and 4 μL of Au (10 mM) in a 50 μL 0.2 M NaOAc buffer (pH = 3.5). The experiments involved altering the concentration of H2O2 (100–1000 mM) while keeping the concentration of TMB fixed at 1000 μM and vice versa by varying the TMB concentration (100–1000 μM) while maintaining a fixed H2O2 concentration of 700 mM. The Michaelis–Menten equation for the catalytic system is presented as follows: (51)
迈克尔-门顿动力学参数表示为最大反应速率（Vmax）和迈克尔-门顿常数（Km）。稳态动力学实验在 40 ℃ 下进行，在 50 μL 0.2 M NaOAc 缓冲溶液（pH = 3.5）中加入 4 μL pSi（8 mg/mL）和 4 μL Au（10 mM）。实验涉及改变 H2O2（100-1000 mM），同时将 TMB 的浓度固定在 1000 μM；反之亦然，改变 TMB 的浓度（100-1000 μM），同时将 H2O2 的浓度固定在 700 mM。催化系统的 Michaelis-Menten 方程如下：(51)where V0 is the rate of substrate conversion to product, Vmax is the maximum rate of conversion, which is obtained when the substrate saturates the enzyme’s active (catalytic) sites, [S] is the substrate concentration, and Km is the Michaelis–Menten constant, reflecting the enzyme’s affinity for the substrate and indicating equal to the substrate concentration where the conversion rate is half that of Vmax.
其中，V0 是底物转化为产物的速率，Vmax 是最大转化速率、是底物达到酶的活性（催化）位点饱和时的最大转化率，[S] 是底物浓度、和 Km 是迈克尔斯-门顿常数，反映了酶对底物的亲和力，表示等于转化率为 Vmax 的一半时的底物浓度。
迈克尔-门顿动力学参数表示为最大反应速率（Vmax）和迈克尔-门顿常数（Km）。稳态动力学实验在 40 ℃ 下进行，在 50 μL 0.2 M NaOAc 缓冲溶液（pH = 3.5）中加入 4 μL pSi（8 mg/mL）和 4 μL Au（10 mM）。实验涉及改变 H2O2（100-1000 mM），同时将 TMB 的浓度固定在 1000 μM；反之亦然，改变 TMB 的浓度（100-1000 μM），同时将 H2O2 的浓度固定在 700 mM。催化系统的 Michaelis-Menten 方程如下：(51)
(1)
其中，V0 是底物转化为产物的速率，Vmax 是最大转化速率、是底物达到酶的活性（催化）位点饱和时的最大转化率，[S] 是底物浓度、和 Km 是迈克尔斯-门顿常数，反映了酶对底物的亲和力，表示等于转化率为 Vmax 的一半时的底物浓度。
2.7. Homocysteine Detection Using AuNP-pSi
2.7.使用 AuNP-pSi 检测同型半胱氨酸
To demonstrate the use of AuNP-pSi nanozymes as a viable sensing tool, the AuNP-pSi nanohybrids were prepared by mixing equal volumes of pSi (8 mg/mL) with AuCl3 (10 mM). The AuNP-pSi nanohybrids were collected by centrifugation, and the supernatant was removed. Next, AuNP-pSi nanohybrids were suspended in 33 μL of NaOAc buffer (pH 3.5) containing Hcy at different concentrations, which was then incubated for 2 h at room temperature. Subsequently, 700 mM H2O2 and 1000 μM TMB were added to complete the reaction. The reaction solution was incubated for 30 min at 40 °C before recording the absorption at 652 nm. The limit of detection (LOD) and limit of quantification (LOQ) were calculated by using the following equations: LOD = [3.3 × (σ/s)] and LOQ = [10 × (σ/s)], where the coefficients 3.3 and 10 are referred to as expansion factors, acquired at a 95% confidence level, σ is the standard deviation, and s is the slope of the calibration curve. To evaluate the capability of AuNP-pSi for Hcy detection in a real-life sample, two different concentrations of Hcy (100 and 250 μM) were prepared in human serum and diluted with NaOAc buffer (1:9 serum to buffer) before testing by using AuNP-pSi nanozymes. The experimental procedure to detect homocysteine in serum followed that used in buffer.
为了证明 AuNP-pSi 纳米酶是一种可行的传感工具，我们将等体积的 pSi（8 mg/mL）与 AuCl3 (10 mM) 混合，制备了 AuNP-pSi 纳米杂交体。通过离心收集 AuNP-pSi 纳米杂交体，并去除上清液。接着，将 AuNP-pSi 纳米杂交体悬浮在 33 μL 含有不同浓度 Hcy 的 NaOAc 缓冲液（pH 3.5）中，然后在室温下培养 2 小时。随后加入 700 mM H2O2 和 1000 μM TMB 完成反应。反应液在 40 °C 下孵育 30 分钟，然后在 652 nm 波长处记录吸收。检测限（LOD）和定量限（LOQ）按以下公式计算：LOD=[3.3×（σ/s ）]，LOQ=[10×（σ/s ）]，其中系数 3.3 和 10 被称为扩展因子，在 95% 的置信水平下获得，σ 是标准偏差，s 是校准曲线的斜率。为了评估 AuNP-pSi 纳米酶在实际样品中检测 Hcy 的能力，我们在人血清中制备了两种不同浓度的 Hcy（100 和 250 μM），并用 NaOAc 缓冲液（血清与缓冲液的比例为 1:9）稀释，然后使用 AuNP-pSi 纳米酶进行检测。检测血清中同型半胱氨酸的实验步骤与检测缓冲液的步骤相同。
为了证明 AuNP-pSi 纳米酶是一种可行的传感工具，我们将等体积的 pSi（8 mg/mL）与 AuCl3 (10 mM) 混合，制备了 AuNP-pSi 纳米杂交体。通过离心收集 AuNP-pSi 纳米杂交体，并去除上清液。接着，将 AuNP-pSi 纳米杂交体悬浮在 33 μL 含有不同浓度 Hcy 的 NaOAc 缓冲液（pH 3.5）中，然后在室温下培养 2 小时。随后加入 700 mM H2O2 和 1000 μM TMB 完成反应。反应液在 40 °C 下孵育 30 分钟，然后在 652 nm 波长处记录吸收。检测限（LOD）和定量限（LOQ）按以下公式计算：LOD=[3.3×（σ/s ）]，LOQ=[10×（σ/s ）]，其中系数 3.3 和 10 被称为扩展因子，在 95% 的置信水平下获得，σ 是标准偏差，s 是校准曲线的斜率。为了评估 AuNP-pSi 纳米酶在实际样品中检测 Hcy 的能力，我们在人血清中制备了两种不同浓度的 Hcy（100 和 250 μM），并用 NaOAc 缓冲液（血清与缓冲液的比例为 1:9）稀释，然后使用 AuNP-pSi 纳米酶进行检测。检测血清中同型半胱氨酸的实验步骤与检测缓冲液的步骤相同。
2.8. AuNP-pSi Selectivity
2.8.AuNP-pSi 的选择性
The selectivity of AuNP-pSi nanozymes toward Hcy was evaluated in the presence of different amino acids (alanine, phenylalanine, leucine, lysine, glycine, and l-aspartic acid). The fluorenylmethyloxycarbonyl (Fmoc)-protected amino acids, viz. Fmoc-alanine–OH, Fmoc-phenylalanine–OH, Fmoc-leucine–OH, and Fmoc-lysine-Fmoc–OH, were deprotected using 20% (v/v) piperidine in dimethylformamide (DMF) before utilizing them in the reaction. Briefly, 50 mg of Fmoc-amino acids were dissolved in 1000 μL of 20% v/v piperidine in DMF and mixed for 15–20 min using a rotary mixer. Subsequently, the deprotected amino acids were precipitated out by using ice-cold diethyl ether (∼10 mL). The suspension was then centrifuged at 10,000g for 10 min. The supernatant was discarded, and the pellet was rinsed twice with 10 mL of ice-cold diethyl ether. The deprotected amino acids were then dried under a vacuum overnight and used in the experiment. In the selectivity experiment, a chemical reaction was carried out by preparing a mixture of AuNP-pSi and NaOAc buffer (pH 3.5). Subsequently, a solution of each amino acid with a concentration of 100 μM was added separately to the mixture, which was then incubated at room temperature for 2 h. Colorimetric measurements were carried out by adding a solution containing 700 mM H2O2 and 1000 μM TMB, and the reaction mixture was incubated for 30 min at a temperature of 40 °C before measuring the absorbance at 652 nm.
评估了 AuNP-pSi 纳米酶在不同氨基酸（丙氨酸、苯丙氨酸、亮氨酸、赖氨酸、甘氨酸和 l- 天冬氨酸）存在下对 Hcy 的选择性。芴甲氧羰基（Fmoc）保护的氨基酸，即 Fmoc-丙氨酸-OH、Fmoc-苯丙氨酸-OH、Fmoc-亮氨酸-OH 和 Fmoc-赖氨酸-Fmoc-OH，在反应中使用之前，先用 20% (v/v) 哌啶在二甲基甲酰胺（DMF）中进行脱保护。简单地说，将 50 毫克 Fmoc- 氨基酸溶解在 1000 微升含 20% (v/v) 哌啶的 DMF 中，然后用旋转搅拌器搅拌 15-20 分钟。然后用冰冷的二乙醚（∼10 mL）沉淀去保护的氨基酸。然后将悬浮液在 10,000g 下离心 10 分钟。弃去上清液，用 10 mL 冰冷的二乙醚冲洗颗粒两次。然后将脱保护的氨基酸在真空中干燥过夜并用于实验。在选择性实验中，通过制备 AuNP-pSi 和 NaOAc 缓冲液（pH 值为 3.5）的混合物来进行化学反应。随后，向混合物中分别加入浓度为 100 μM 的每种氨基酸溶液，然后在室温下孵育 2 小时。通过加入含有 700 mM H2O2 和 1000 μM TMB 的溶液进行比色测量，反应混合物在 40 °C 温度下孵育 30 分钟，然后在 652 纳米波长处测量吸光度。
评估了 AuNP-pSi 纳米酶在不同氨基酸（丙氨酸、苯丙氨酸、亮氨酸、赖氨酸、甘氨酸和 l- 天冬氨酸）存在下对 Hcy 的选择性。芴甲氧羰基（Fmoc）保护的氨基酸，即 Fmoc-丙氨酸-OH、Fmoc-苯丙氨酸-OH、Fmoc-亮氨酸-OH 和 Fmoc-赖氨酸-Fmoc-OH，在反应中使用之前，先用 20% (v/v) 哌啶在二甲基甲酰胺（DMF）中进行脱保护。简单地说，将 50 毫克 Fmoc- 氨基酸溶解在 1000 微升含 20% (v/v) 哌啶的 DMF 中，然后用旋转搅拌器搅拌 15-20 分钟。然后用冰冷的二乙醚（∼10 mL）沉淀去保护的氨基酸。然后将悬浮液在 10,000g 下离心 10 分钟。弃去上清液，用 10 mL 冰冷的二乙醚冲洗颗粒两次。然后将脱保护的氨基酸在真空中干燥过夜并用于实验。在选择性实验中，通过制备 AuNP-pSi 和 NaOAc 缓冲液（pH 值为 3.5）的混合物来进行化学反应。随后，向混合物中分别加入浓度为 100 μM 的每种氨基酸溶液，然后在室温下孵育 2 小时。通过加入含有 700 mM H2O2 和 1000 μM TMB 的溶液进行比色测量，反应混合物在 40 °C 温度下孵育 30 分钟，然后在 652 纳米波长处测量吸光度。
3. Results and Discussion
3.结果与讨论
Click to copy section link
点击复制章节链接Section link copied!
点击复制章节链接Section link copied!
3.1. Synthesis of AuNP-pSi Nanohybrids
3.1.AuNP-pSi 纳米杂化物的合成
TEM (Figure 2a) shows a typical random-shaped flat sheet-like profile of pSi particles with vertically running pores clearly visible in Figure 2a and the high-magnification top view in the inset of Figure 2a. The TEM images of AuNP-pSi nanozymes with different pSi:Au ratios (v:v; 4:1, 1:1, and 1:4) along with digital photographs and elemental mapping are presented in Figure 2b–j. The spontaneously formed AuNPs are evident on the surface of pSi particles after mixing of pSi particles with Au salt solution at all concentrations. The pSi suspension exhibited a typical yellow color (Figure 2a, inset). While upon addition of Au salt solution, the mixture turned to different shades of red. The 4:1 pSi:Au ratio exhibited a light pink color, and the 1:1 pSi:Au ratio resulted in an even darker red color. The 1:4 pSi:Au ratio, which contains the highest amount of Au in the mixture, exhibited gray color. The TEM (Figure 2b) and the elemental mapping (Figure 2e–j) images also show a correlation between the density of AuNPs on the pSi surface with the starting ratio of the two components in the reaction. The composition analysis of the AuNP-pSi nanozyme with different pSi:Au ratios of 4:1, 1:1, and 1:4 revealed the presence of both pSi (Figure 2e–g) and Au (Figure 2h–j). In this regard, a higher density of AuNPs was observed with an increasing amount of Au salt solution, which is evident from the Au elemental mapping images in Figure 2h–j for the pSi:Au ratio changing from 4:1 to 1:4. For all of the AuNP-pSi nanohybrids, interestingly, AuNPs predominantly appeared to be associated with pSi particles thus indicating the formation of a nanohybrid instead of free-standing AuNPs. The average size of AuNPs on the pSi surface was found to be 45 nm for the 4:1 ratio, 16 nm for the 1:1 ratio, and 25 nm for the 1:4 ratio, measured using ImageJ. DLS particle size analysis was carried out to obtain the average particle size for pSi and AuNP-pSi nanohybrids prepared from different ratios of pSi:Au (Figure S1). The AuNP-pSi nanohybrids, on the other hand, showed a much greater aggregation. The pSi:Au ratio of 4:1 showed a predominant particle size distribution peak at around 280 nm and a broad secondary peak at around 11,750 nm, which was similar to that of the 1:4 (v:v) pSi:Au ratio that clearly points to the aggregation behavior. Additionally, the pSi:Au ratio of 1:4 showed another predominant particle size distribution peak at around 1216 nm. This secondary peak is associated with aggregation of the particles. The AuNP-pSi nanohybrids prepared using the 1:1 pSi to Au ratio showed the least aggregation with a predominant peak at around 190 nm and a small shoulder peak (3000 nm). This indicates the presence of aggregates for all three samples, while the 1:1 pSi:Au ratio samples show the least aggregated particle formation. The UV–vis spectra for pSi alone and AuNP-pSi with different pSi:Au ratios of 4:1, 1:1, and 1:4 were recorded, respectively. The absorbance curve for pSi shows no plasmonic peak, while a very small but evident plasmonic peak appears at around 550 nm for pSi:Au (4:1). The plasmonic peak became more prominent and shifted close to 560 nm for AuNP-pSi nanohybrids fabricated with pSi:Au ratios with higher Au amounts (Figure S2). It is worth noting that the ζ-potentials of both pSi and AuNP-pSi were highly negative with values −47.89 and −33.83 mV, respectively, upon addition of Au salt solution, which served as a visual indicator for the successful synthesis of the AuNP-pSi nanozyme (digital photographs in Figure 2 and Video S1).
在图 2a和图 2a的插图中的高倍俯视图中，TEM（图 2a）显示了典型的随机形状的扁平片状 pSi 颗粒轮廓，垂直分布的孔隙清晰可见。不同 pSi:Au 比例（v:v；4:1、1:1 和 1:4）的 AuNP-pSi 纳米分子的 TEM 图像以及数码照片和元素图谱见 Figure 2b-j。将所有浓度的 pSi 颗粒与金盐溶液混合后，在 pSi 颗粒表面都能看到自发形成的 AuNPs。pSi 悬浮液呈现典型的黄色（图 2a，插图）。而加入金盐溶液后，混合物变成了深浅不同的红色。4:1 pSi:Au 比例的混合物呈现淡粉色，而 1:1 pSi:Au 比例的混合物则呈现更深的红色。1:4 pSi:Au 比例的混合物中金含量最高，呈现灰色。TEM (图 2b)和元素图谱 (图 2e-j)图像也显示了 pSi 表面 AuNPs 密度与反应中两种成分的起始比例之间的相关性。对不同 pSi:Au 比率（4:1、1:1 和 1:4）的 AuNP-pSi 纳米酶的成分分析表明，pSi（图 2e-g）和 Au（图 2h-j）同时存在。从 Figure 2h-j 中 pSi:Au 比例从 4:1 变为 1:4 时的 Au 元素映射图像中可以明显看出，随着 Au 盐溶液量的增加，AuNPs 的密度更高。 有趣的是，在所有 AuNP-pSi 纳米杂化物中，AuNPs 似乎主要与 pSi 颗粒结合在一起，这表明形成了纳米杂化物，而不是独立的 AuNPs。使用 ImageJ 测量发现，pSi 表面 AuNPs 的平均尺寸在 4:1 比例时为 45 nm，在 1:1 比例时为 16 nm，在 1:4 比例时为 25 nm。通过 DLS 粒度分析，获得了 pSi 和用不同比例的 pSi:Au 制备的 AuNP-pSi 纳米杂化物的平均粒度（图 S1）。另一方面，AuNP-pSi 纳米杂化物显示出更大的聚集性。pSi:Au 的比例为 4:1 时，在 280 nm 左右出现了一个主要的粒度分布峰，在 11,750 nm 左右出现了一个宽阔的次要峰，这与 pSi:Au 的比例为 1:4 （v:v）时的粒度分布峰相似，这清楚地表明了聚集行为。此外，1:4 的 pSi:Au 比例在 1216 纳米左右显示出另一个主要粒度分布峰。这个次峰值与颗粒的聚集有关。使用 1:1 的 pSi 与 Au 比例制备的 AuNP-pSi 纳米杂化物显示出最少的聚集，主要峰值在 190 纳米左右，并有一个小的肩峰（3000 纳米）。这表明所有三种样品中都存在聚集体，而 1:1 pSi:Au 比例的样品显示出最少的聚集颗粒形成。分别记录了单独 pSi 和不同 pSi:Au 比例（4:1、1:1 和 1:4）的 AuNP-pSi 的紫外可见光谱。pSi 的吸光度曲线未显示等离子峰，而 pSi:Au (4:1) 的吸光度曲线在 550 纳米左右出现了一个非常小但明显的等离子峰。 对于金含量较高的 pSi:Au 比率制备的 AuNP-pSi 纳米杂交材料，等离子峰变得更加突出，并向 560 纳米附近移动（图 S2）。值得注意的是，加入金盐溶液后，pSi 和 AuNP-pSi 的ζ电位均为高度负值，分别为 -47.89 和 -33.83 mV，这是成功合成 AuNP-pSi 纳米酶的直观指标（图 2 和视频 S1 中的数码照片）。
在图 2a和图 2a的插图中的高倍俯视图中，TEM（图 2a）显示了典型的随机形状的扁平片状 pSi 颗粒轮廓，垂直分布的孔隙清晰可见。不同 pSi:Au 比例（v:v；4:1、1:1 和 1:4）的 AuNP-pSi 纳米分子的 TEM 图像以及数码照片和元素图谱见 Figure 2b-j。将所有浓度的 pSi 颗粒与金盐溶液混合后，在 pSi 颗粒表面都能看到自发形成的 AuNPs。pSi 悬浮液呈现典型的黄色（图 2a，插图）。而加入金盐溶液后，混合物变成了深浅不同的红色。4:1 pSi:Au 比例的混合物呈现淡粉色，而 1:1 pSi:Au 比例的混合物则呈现更深的红色。1:4 pSi:Au 比例的混合物中金含量最高，呈现灰色。TEM (图 2b)和元素图谱 (图 2e-j)图像也显示了 pSi 表面 AuNPs 密度与反应中两种成分的起始比例之间的相关性。对不同 pSi:Au 比率（4:1、1:1 和 1:4）的 AuNP-pSi 纳米酶的成分分析表明，pSi（图 2e-g）和 Au（图 2h-j）同时存在。从 Figure 2h-j 中 pSi:Au 比例从 4:1 变为 1:4 时的 Au 元素映射图像中可以明显看出，随着 Au 盐溶液量的增加，AuNPs 的密度更高。 有趣的是，在所有 AuNP-pSi 纳米杂化物中，AuNPs 似乎主要与 pSi 颗粒结合在一起，这表明形成了纳米杂化物，而不是独立的 AuNPs。使用 ImageJ 测量发现，pSi 表面 AuNPs 的平均尺寸在 4:1 比例时为 45 nm，在 1:1 比例时为 16 nm，在 1:4 比例时为 25 nm。通过 DLS 粒度分析，获得了 pSi 和用不同比例的 pSi:Au 制备的 AuNP-pSi 纳米杂化物的平均粒度（图 S1）。另一方面，AuNP-pSi 纳米杂化物显示出更大的聚集性。pSi:Au 的比例为 4:1 时，在 280 nm 左右出现了一个主要的粒度分布峰，在 11,750 nm 左右出现了一个宽阔的次要峰，这与 pSi:Au 的比例为 1:4 （v:v）时的粒度分布峰相似，这清楚地表明了聚集行为。此外，1:4 的 pSi:Au 比例在 1216 纳米左右显示出另一个主要粒度分布峰。这个次峰值与颗粒的聚集有关。使用 1:1 的 pSi 与 Au 比例制备的 AuNP-pSi 纳米杂化物显示出最少的聚集，主要峰值在 190 纳米左右，并有一个小的肩峰（3000 纳米）。这表明所有三种样品中都存在聚集体，而 1:1 pSi:Au 比例的样品显示出最少的聚集颗粒形成。分别记录了单独 pSi 和不同 pSi:Au 比例（4:1、1:1 和 1:4）的 AuNP-pSi 的紫外可见光谱。pSi 的吸光度曲线未显示等离子峰，而 pSi:Au (4:1) 的吸光度曲线在 550 纳米左右出现了一个非常小但明显的等离子峰。 对于金含量较高的 pSi:Au 比率制备的 AuNP-pSi 纳米杂交材料，等离子峰变得更加突出，并向 560 纳米附近移动（图 S2）。值得注意的是，加入金盐溶液后，pSi 和 AuNP-pSi 的ζ电位均为高度负值，分别为 -47.89 和 -33.83 mV，这是成功合成 AuNP-pSi 纳米酶的直观指标（图 2 和视频 S1 中的数码照片）。
Figure 2 图 2
Figure 2. TEM images and digital photographs of (a) a cross-sectional view of a pSi particle, with the inset showing the high-magnification top view of a single particle. The vertically running pores of pSi are visible in the TEM images. The scale bar is 200 nm, while for inset it is 100 nm. The inset also shows a digital photograph of the pSi suspension at 8 mg/mL concentration. TEM images and digital photographs of AuNP-pSi nanohybrids at different pSi:Au (v:v) ratios. (b) TEM image of AuNP-pSi prepared with 4:1 pSi:Au ratio with inset showing a digital photograph of the corresponding sample. The scale bar is 250 nm. (c) TEM image of AuNP-pSi prepared with 1:1 pSi:Au ratio with inset showing a digital photograph of the same sample. The scale bar is 100 nm. (d) TEM image of AuNP-pSi prepared with 1:4 pSi:Au ratio with inset showing a digital photograph of that sample. The scale bar is 200 nm. (e–g) TEM-EDS elemental mapping of Si for AuNP-pSi prepared from (e) 4:1 pSi:Au, (f) 1:1 pSi:Au, and (g) 1:4 pSi:Au ratios. TEM-EDS elemental mapping of Au for AuNPs-pSi prepared from (h) 4:1 pSi:Au, (i) 1:1 pSi:Au, and (j) 1:4 pSi:Au ratios.
图 2.(a) pSi 粒子横截面的 TEM 图像和数码照片，插图为单个粒子的高倍俯视图。在 TEM 图像中可以看到 pSi 垂直分布的孔隙。刻度线为 200 纳米，插图中为 100 纳米。插图还显示了浓度为 8 毫克/毫升的 pSi 悬浮液的数码照片。不同 pSi：Au（v：v）比例的 AuNP-pSi 纳米杂化物的 TEM 图像和数码照片。(b) 以 4:1 pSi:Au 比例制备的 AuNP-pSi 的 TEM 图像和相应样品的数码照片。刻度线为 250 纳米。(c) 以 1:1 pSi:Au 比例制备的 AuNP-pSi 的 TEM 图像，插图为同一样品的数码照片。刻度线为 100 纳米。(d) 以 1:4 pSi:Au 比例制备的 AuNP-pSi 的 TEM 图像，插图为该样品的数码照片。刻度线为 200 纳米。(e-g）以（e）4:1 pSi:Au、（f）1:1 pSi:Au、（g）1:4 pSi:Au 比例制备的 AuNP-pSi 的 TEM-EDS 元素图谱。用 (h) 4:1 pSi:Au、(i) 1:1 pSi:Au 和 (j) 1:4 pSi:Au 比例制备的 AuNPs-pSi 的 Au 的 TEM-EDS 元素图谱。
The crystallographic properties of pSi and AuNP-pSi nanohybrid were assessed by XRD in the range 10–100°. From Figure S3, XRD spectra of the pSi sample (Figure S3a) exhibited seven diffraction peaks at 28.49, 47.29, 56.04, 69.12, 76.23, 87.72, and 94.72° that correspond to the (111), (220), (311), (400), (331), (442), and (511) planes (JCPDS card nos. 01-079-0613 and 00-027-1402). (52) While for AuNP-pSi (Figure S3b), a peak at 28.58° corresponds to (111) for (pSi), and major diffraction peaks from gold can be observed at 2θ values of 38.32, 44.49, 64.65, 77.72, 81.79, and 98.24°, which correspond to the (111), (200), (220), (311), (222), and (400) crystalline planes, as documented in the JCPDS file: 04-0784. (53) An observable (111) diffraction peak indicates a significant development of the network structure in the (111) plane compared to other orientations. This further confirmed the successful synthesis of the AuNP-pSi nanohybrid.
在 10-100° 范围内通过 XRD 评估了 pSi 和 AuNP-pSi 纳米杂化物的晶体学特性。从图 S3中可以看出，pSi 样品的 XRD 图谱（图 S3a）在 28.49、47.29、56.04、69.12、76.23、87.72 和 94.72°，分别对应于 (111)、(220)、(311)、(400)、(331)、(442) 和 (511) 平面（JCPDS 证号：01-079-0613 和 00-027-1402）。(52)而对于 AuNP-pSi（图 S3b），28.58°处的峰对应于 (pSi) 的 (111)，在 2θ 值为 38.32、44.49、64.65、77.72、81.79 和 98.24°，对应于 (111)、(200)、(220)、(311)、(222) 和 (400) 晶面：04-0784.(53) 可观察到的(111)衍射峰表明，与其他方向相比，(111)面的网络结构有了显著发展。这进一步证实了 AuNP-pSi 纳米杂化物的成功合成。
在 10-100° 范围内通过 XRD 评估了 pSi 和 AuNP-pSi 纳米杂化物的晶体学特性。从图 S3中可以看出，pSi 样品的 XRD 图谱（图 S3a）在 28.49、47.29、56.04、69.12、76.23、87.72 和 94.72°，分别对应于 (111)、(220)、(311)、(400)、(331)、(442) 和 (511) 平面（JCPDS 证号：01-079-0613 和 00-027-1402）。(52)而对于 AuNP-pSi（图 S3b），28.58°处的峰对应于 (pSi) 的 (111)，在 2θ 值为 38.32、44.49、64.65、77.72、81.79 和 98.24°，对应于 (111)、(200)、(220)、(311)、(222) 和 (400) 晶面：04-0784.(53) 可观察到的(111)衍射峰表明，与其他方向相比，(111)面的网络结构有了显著发展。这进一步证实了 AuNP-pSi 纳米杂化物的成功合成。
3.2. Activity Mechanism of Peroxidase-like AuNP-pSi Nanohybrid
3.2.过氧化物酶类 AuNP-pSi 纳米杂交的活性机制
Natural peroxidases like HRP and peroxidase-imitating nanozymes can catalyze TMB in the presence of H2O2 to generate a blue one-electron oxidation product (TMBox) that absorbs light at 652 nm and can be utilized for both qualitative (visual inspection) and quantitative UV–vis quantification of the reaction. (50,54) The peroxidase-mimicking activity of the freshly activated AuNP-pSi nanohybrid was studied by using the same colorimetric reaction. To confirm on-demand activatable peroxidase-like activity, a set of TMB oxidation experiments were conducted with pSi before and after the formation of AuNPs on its surface. As shown in Figure S4 and Video S1, it is evident that only AuNP-pSi catalyzed the oxidation of TMB and generated a blue-color solution, while no color change was observed for pSi alone. This visual indication confirms that the AuNP-pSi nanohybrid exhibits peroxidase-like activity, which can be activated on demand by simple mixing of the pSi particle suspension and a gold salt solution. The UV–vis spectra for pSi, AuNP-pSi, AuNP-pSi + H2O2, and AuNP-pSi + H2O2 + TMB were recorded. The appearance of a plasmonic resonance at around 560 nm evidenced successful synthesis of the AuNP-pSi nanohybrid, which showed no significant change upon addition of H2O2 alone. As expected, a prominent peak corresponding to oxidized TMB appeared at around 652 nm when a mixture of H2O2 with TMB was introduced, indicating strong nanozymatic activity (Figure 3a). The mechanism of Au nanoparticle formation and its catalytic activity are explained in Section S1.6.
天然过氧化物酶（如 HRP）和过氧化物酶模拟纳米酶可在 H2O2 存在下催化 TMB 生成蓝色单电子氧化产物（TMBox），该产物在 652 纳米波长处吸收光，可用于反应的定性（目测）和紫外可见光定量分析。(50,54) 利用相同的比色反应研究了新鲜活化的 AuNP-pSi 纳米杂交体的过氧化物酶模拟活性。为了证实按需活化的过氧化物酶样活性，在 pSi 表面形成 AuNPs 之前和之后对其进行了一组 TMB 氧化实验。如图 S4 和视频 S1 所示，显然只有 AuNP-pSi 才能催化 TMB 氧化并生成蓝色溶液，而单独使用 pSi 则观察不到颜色变化。这一直观显示证实了 AuNP-pSi 纳米杂化物具有类似过氧化物酶的活性，只需将 pSi 颗粒悬浮液与金盐溶液混合即可按需激活。记录了 pSi、AuNP-pSi、AuNP-pSi + H2O2 和 AuNP-pSi + H2O2 + TMB 的紫外可见光谱。在 560 纳米波长附近出现的等离子体共振证明 AuNP-pSi 纳米杂化物的合成是成功的，在单独加入 H2O2 后没有发生明显变化。 不出所料，当引入 H2O2 与 TMB 的混合物时，在 652 纳米波长处出现了与氧化 TMB 相对应的突出峰值，这表明纳米催化活性很强（图 3a）。金纳米粒子的形成机理及其催化活性将在S1.6节中解释。
天然过氧化物酶（如 HRP）和过氧化物酶模拟纳米酶可在 H2O2 存在下催化 TMB 生成蓝色单电子氧化产物（TMBox），该产物在 652 纳米波长处吸收光，可用于反应的定性（目测）和紫外可见光定量分析。(50,54) 利用相同的比色反应研究了新鲜活化的 AuNP-pSi 纳米杂交体的过氧化物酶模拟活性。为了证实按需活化的过氧化物酶样活性，在 pSi 表面形成 AuNPs 之前和之后对其进行了一组 TMB 氧化实验。如图 S4 和视频 S1 所示，显然只有 AuNP-pSi 才能催化 TMB 氧化并生成蓝色溶液，而单独使用 pSi 则观察不到颜色变化。这一直观显示证实了 AuNP-pSi 纳米杂化物具有类似过氧化物酶的活性，只需将 pSi 颗粒悬浮液与金盐溶液混合即可按需激活。记录了 pSi、AuNP-pSi、AuNP-pSi + H2O2 和 AuNP-pSi + H2O2 + TMB 的紫外可见光谱。在 560 纳米波长附近出现的等离子体共振证明 AuNP-pSi 纳米杂化物的合成是成功的，在单独加入 H2O2 后没有发生明显变化。 不出所料，当引入 H2O2 与 TMB 的混合物时，在 652 纳米波长处出现了与氧化 TMB 相对应的突出峰值，这表明纳米催化活性很强（图 3a）。金纳米粒子的形成机理及其催化活性将在S1.6节中解释。
Figure 3 图 3
Figure 3. UV–vis absorbance at 652 nm for TMB upon oxidation with the AuNP-pSi nanozyme under different conditions. (a) UV–vis spectra for (i) AuNP-pSi, (ii) AuNP-pSi + H2O2, and (iii) AuNP-pSi+H2O2 + TMB. The plasmonic resonance around 560 nm in (ii) can be attributed to AuNPs in the nanohybrid, and a prominent peak appearing at around 652 nm in (iii) is attributed to the oxidized form of TMB formed after reaction with the AuNP-pSi nanozyme. (b) Effects of different ratios of pSi:Au (v:v) when the concentration of the pSi suspension was 8 mg/mL and the Au(III) solution was 10 mM. (c) Effect of the operating pH tested on a 1:1 pSi:Au (v:v) sample. (d) Effect of the working temperature tested on the 1:1 pSi:Au (v:v) sample. (e) TMB oxidation activity of AuNP-pSi measured in the absence and presence of a hydroxide radical scavenger (ascorbic acid; AA; 5 mM). The activity is normalized to the control without AA. Ascorbic acid scavenger absorbs the hydroxyl radical, resulting in lower absorbance than that of the control (AuNP-pSi). (f) Fluorescence spectra of 2-hydroxyterephthalic acid (excited at 315 nm) in the presence of the AuNP-pSi nanozyme at concentrations ranging from 16 to 160 μg. (g) Nanozyme activity retention of AuNP-pSi (red bar) and HRP (green bar) after incubation at different temperatures (40, 60, 80, and 100 °C) for 5 min. (h) Long-term storage stability of the AuNP-pSi nanozyme represented in terms of activity to oxidize TMB. The activity is normalized to a AuNP-pSi nanozyme sample prepared from freshly etched pSi particles and Au(III) solution. These experiments were carried out at 25 °C in 0.2 M NaOAc buffer (pH 3.5) reaction mixture containing 700 mM H2O2 and 1000 μM TMB. Error bars represent the standard deviation of three measurements.
图 3.在不同条件下，TMB 与 AuNP-pSi 纳米酶氧化后在 652 纳米波长处的紫外-可见吸收率。(a) (i) AuNP-pSi、(ii) AuNP-pSi + H2O2 和 (iii) AuNP-pSi+H2O2 + TMB 的紫外可见光谱。(ii)中 560 纳米附近的等离子共振可归因于纳米杂交中的 AuNPs，而(iii)中 652 纳米附近出现的突出峰值则归因于 TMB 与 AuNP-pSi 纳米酶反应后形成的氧化形式。(b) 当 pSi 悬浮液的浓度为 8 mg/mL、Au(III) 溶液的浓度为 10 mM 时，pSi:Au（v:v）不同比例的影响。(c) 对 1:1 pSi:Au (v:v) 样品测试的工作 pH 值的影响。(d) 工作温度对 1:1 pSi:Au (v:v) 样品的影响。(e) 在没有和有氢氧自由基清除剂（抗坏血酸；AA；5 mM）的情况下测量的 AuNP-pSi 的 TMB 氧化活性。活性与不含 AA 的对照正常化。抗坏血酸清除剂吸收羟自由基，导致吸光度低于对照组（AuNP-pSi）。(f) 在 AuNP-pSi 纳米酶浓度为 16 至 160 μg 的情况下，2-羟基对苯二甲酸的荧光光谱（激发波长为 315 nm）。(g) AuNP-pSi（红条）和 HRP（绿条）在不同温度（40、60、80 和 100 ℃）下孵育 5 分钟后的纳米酶活性保持情况。 (h) AuNP-pSi 纳米酶的长期储存稳定性，以氧化 TMB 的活性表示。该活性与用新蚀刻的 pSi 颗粒和 Au（III）溶液制备的 AuNP-pSi 纳米酶样品进行了归一化。这些实验在 25 °C、0.2 M NaOAc 缓冲溶液（pH 值为 3.5) 含 700 mM H2O2 和 1000 μM TMB 的反应混合物。误差条代表三次测量的标准偏差。
First, the effects of the ratio of pSi to Au (Figure 3b) on the TMB oxidation reaction were evaluated. This was carried out by mixing different volumes of an 8 mg/mL aqueous suspension of pSi with different volumes of a 10 mM aqueous Au3+ ionic solution. It appears that a 1:1 volume ratio of pSi to Au3+ ions (at aforementioned concentrations) provided the greatest TMB oxidation as shown in Figure 3b. The increase in nanozyme activity from 4:1 to 1:1 ratio of pSi to Au could be attributed to increasing numbers of AuNPs on the pSi surface. Interestingly, while AuNP density increases upon further increasing Au3+ ions during AuNP-pSi generation (i.e., increasing the pSi:Au ratio to 1:4), the nanozyme activity decreased. This could be related to high packing of AuNPs on the pSi surface that reduces the surface area available for catalyzing TMB oxidation reaction compared to well-dispersed AuNPs on the 1:1 pSi:Au sample. Next, the effects of operating pH and reaction temperature were investigated by examining the peroxidase-like activity of AuNP-pSi using different solution pH levels ranging from 2.5 to 7.5 at different reaction temperatures from 25 to 45 °C. It was observed that solution pH strongly affects the activity of AuNP-pSi. The peak AuNP-pSi activity was observed at pH 3.5, while a decrease in activity was noticed with the increase of the pH of the solution (Figure 3c). This behavior is well reported for peroxidase-mimicking enzymes and could be because at higher pH HO2• can be ionized into O2–, according to eq 2. In addition, HO2• can quickly create oxygen by interacting with hydroxyl radicals (eq 3). (55)
首先，评估了 pSi 与 Au 的比例（图 3b）对 TMB 氧化反应的影响。具体方法是将不同体积的 8 mg/mL pSi 水悬浮液与不同体积的 10 mM Au3+ 离子水溶液混合。如图 3b 所示，pSi 与 Au3+ 离子的体积比为 1:1（上述浓度）时，TMB 的氧化作用最大。纳米酶活性从 pSi 与 Au 的比例为 4:1 增加到 1:1，可能是因为 pSi 表面的 AuNPs 数量增加了。有趣的是，虽然在 AuNP-pSi 生成过程中进一步增加 Au3+ 离子（即 pSi:Au 比增加到 1:4）会增加 AuNP 密度，但纳米酶活性却降低了。这可能与 pSi 表面的 AuNPs 高度堆积有关，与 1:1 pSi:Au 样品上分散良好的 AuNPs 相比，pSi:Au 样品上的 AuNPs 高度堆积减少了可用于催化 TMB 氧化反应的表面积。接下来，研究人员使用 2.5 至 7.5 的不同溶液 pH 值和 25 至 45 °C 的不同反应温度，考察了 AuNP-pSi 的过氧化物酶样活性，从而研究了操作 pH 值和反应温度的影响。结果表明，溶液的 pH 值对 AuNP-pSi 的活性有很大影响。在 pH 值为 3.5 时，AuNP-pSi 的活性达到峰值，而随着溶液 pH 值的增加，活性则有所下降（图 3c）。 这种行为在过氧化物酶模拟酶中已有大量报道，可能是因为在较高的 pH 值下，根据 eq 2，HO2- 可以电离成 O2- 。此外，HO2- 可以通过与羟基自由基相互作用迅速产生氧气（eq 3）。(55)For the reaction temperature, the peroxidase catalytic activities of AuNP-pSi were found to increase with increasing the reaction temperature up to 40 °C. A sharp decrease was observed when the operating temperature was increased further (Figure 3d). According to the experimental results shown in Figure 3b–d, the optimal volume ratio of pSi (8 mg/mL):Au (10 mM AuCl3), pH value, and reaction temperature were 1:1, 3.5, and 40 °C, respectively. These optimal conditions were used for all further experiments unless stated otherwise.
在反应温度方面，发现 AuNP-pSi 的过氧化物酶催化活性随着反应温度的升高而增加，最高可达 40 °C。当操作温度进一步升高时，发现活性急剧下降（图 3d）。根据图 3b-d所示的实验结果，pSi（8 mg/mL）：Au（10 mM AuCl3）的最佳体积比、pH 值和反应温度分别为 1:1、3.5 和 40 ℃。除非另有说明，否则所有后续实验均采用这些最佳条件。
首先，评估了 pSi 与 Au 的比例（图 3b）对 TMB 氧化反应的影响。具体方法是将不同体积的 8 mg/mL pSi 水悬浮液与不同体积的 10 mM Au3+ 离子水溶液混合。如图 3b 所示，pSi 与 Au3+ 离子的体积比为 1:1（上述浓度）时，TMB 的氧化作用最大。纳米酶活性从 pSi 与 Au 的比例为 4:1 增加到 1:1，可能是因为 pSi 表面的 AuNPs 数量增加了。有趣的是，虽然在 AuNP-pSi 生成过程中进一步增加 Au3+ 离子（即 pSi:Au 比增加到 1:4）会增加 AuNP 密度，但纳米酶活性却降低了。这可能与 pSi 表面的 AuNPs 高度堆积有关，与 1:1 pSi:Au 样品上分散良好的 AuNPs 相比，pSi:Au 样品上的 AuNPs 高度堆积减少了可用于催化 TMB 氧化反应的表面积。接下来，研究人员使用 2.5 至 7.5 的不同溶液 pH 值和 25 至 45 °C 的不同反应温度，考察了 AuNP-pSi 的过氧化物酶样活性，从而研究了操作 pH 值和反应温度的影响。结果表明，溶液的 pH 值对 AuNP-pSi 的活性有很大影响。在 pH 值为 3.5 时，AuNP-pSi 的活性达到峰值，而随着溶液 pH 值的增加，活性则有所下降（图 3c）。 这种行为在过氧化物酶模拟酶中已有大量报道，可能是因为在较高的 pH 值下，根据 eq 2，HO2- 可以电离成 O2- 。此外，HO2- 可以通过与羟基自由基相互作用迅速产生氧气（eq 3）。(55)
(2)
(3)
在反应温度方面，发现 AuNP-pSi 的过氧化物酶催化活性随着反应温度的升高而增加，最高可达 40 °C。当操作温度进一步升高时，发现活性急剧下降（图 3d）。根据图 3b-d所示的实验结果，pSi（8 mg/mL）：Au（10 mM AuCl3）的最佳体积比、pH 值和反应温度分别为 1:1、3.5 和 40 ℃。除非另有说明，否则所有后续实验均采用这些最佳条件。
To reveal the mechanism of catalytic activity of AuNP-pSi, AA and TA were used as a scavenger of hydroxyl radicals. (49,50) Upon addition of AA, the activity of AuNP-pSi significantly dropped by 75% compared to the AuNP-pSi sample without AA as shown in Figure 3e. This drastic loss in nanozyme activity of AuNP-pSi confirms that generated •OH radicals were scavenged by AA. Additional investigations were carried out to deepen our understanding of the role played by •OH free radicals. In this experiment, TA was utilized to react with •OH free radicals generated as a result of the AuNP-pSi nanozyme’s activity. When TA interacts with the •OH radical, it leads to the formation of 2-hydroxyterephthalic acid, a highly fluorescent compound that emits light at 430 nm upon excitation at 315 nm. (50) As illustrated in Figure 3f, the control sample (without nanozyme) does not exhibit any fluorescence signals, while the samples containing AuNP-pSi exhibit fluorescence. The quantity of •OH radicals produced increases with the higher amount of nanozyme (ranging from 16 to 160 μg), resulting in more prominent fluorescence signals from 2-hydroxyterephthalic acid, indicating the proportional relationship between the nanozyme amount and •OH radical. The AA and TA-based •OH scavenging data amply demonstrated and validated the hypothesis that oxidation of TMB by the AuNP-pSi nanozyme is predominantly driven by the cleavage of H2O2 and production of •OH radicals. The •OH radicals subsequently oxidize TMB, resulting in a blue reaction product.
为了揭示 AuNP-pSi 催化活性的机理，AA 和 TA 被用作羟基自由基的清除剂。(49,50) 如图 3e所示，加入 AA 后，AuNP-pSi 的活性比不含 AA 的 AuNP-pSi 样品显著下降了 75%。AuNP-pSi 纳米酶活性的急剧下降证实了 AA 清除了产生的 -OH 自由基。为了加深对 -OH 自由基所起作用的理解，我们还进行了其他研究。在该实验中，我们利用 TA 与 AuNP-pSi 纳米酶活性产生的 -OH 自由基发生反应。当 TA 与 -OH 自由基相互作用时，会形成 2- 羟基对苯二甲酸，这是一种高荧光化合物，在 315 纳米波长的激发下会在 430 纳米波长处发光。(50) 如 Figure 3f 所示，对照样品（不含纳米酶）不显示任何荧光信号，而含有 AuNP-pSi 的样品则显示荧光。产生的 -OH 自由基的数量随着纳米酶用量的增加而增加（从 16 微克到 160 微克不等），从而导致 2- 羟基对苯二甲酸的荧光信号更加突出，这表明纳米酶用量与 -OH 自由基之间存在比例关系。 基于 AA 和 TA 的 -OH 清除数据充分证明并验证了以下假设：AuNP- pSi 纳米酶对 TMB 的氧化作用主要是通过裂解 H2O-OH 来实现的。pSi 纳米酶主要通过裂解 H2O2 和产生 -OH 自由基来驱动 TMB 氧化。-OH 自由基随后氧化 TMB，生成蓝色反应产物。
为了揭示 AuNP-pSi 催化活性的机理，AA 和 TA 被用作羟基自由基的清除剂。(49,50) 如图 3e所示，加入 AA 后，AuNP-pSi 的活性比不含 AA 的 AuNP-pSi 样品显著下降了 75%。AuNP-pSi 纳米酶活性的急剧下降证实了 AA 清除了产生的 -OH 自由基。为了加深对 -OH 自由基所起作用的理解，我们还进行了其他研究。在该实验中，我们利用 TA 与 AuNP-pSi 纳米酶活性产生的 -OH 自由基发生反应。当 TA 与 -OH 自由基相互作用时，会形成 2- 羟基对苯二甲酸，这是一种高荧光化合物，在 315 纳米波长的激发下会在 430 纳米波长处发光。(50) 如 Figure 3f 所示，对照样品（不含纳米酶）不显示任何荧光信号，而含有 AuNP-pSi 的样品则显示荧光。产生的 -OH 自由基的数量随着纳米酶用量的增加而增加（从 16 微克到 160 微克不等），从而导致 2- 羟基对苯二甲酸的荧光信号更加突出，这表明纳米酶用量与 -OH 自由基之间存在比例关系。 基于 AA 和 TA 的 -OH 清除数据充分证明并验证了以下假设：AuNP- pSi 纳米酶对 TMB 的氧化作用主要是通过裂解 H2O-OH 来实现的。pSi 纳米酶主要通过裂解 H2O2 和产生 -OH 自由基来驱动 TMB 氧化。-OH 自由基随后氧化 TMB，生成蓝色反应产物。
Natural peroxidases such as HRP are known to have poor temperature sensitivity, losing activity very rapidly upon exposure to high storage temperatures. Therefore, they require cold storage and are only used in high-value applications like ELISA assays. As such, a nanozyme with a higher temperature resistance is desired. In this regard, the effect of temperature on the enzymatic performance of the AuNP-pSi nanohybrid was investigated by exposing the two components of the hybrids to various temperatures (40, 60, 80, and 100 °C) for 45 min. Natural HRP served as a comparative control for this experiment. After 45 min of exposure to these temperatures, TMB oxidation activity of both AuNP-pSi and HRP was noted (Figure 3g). It appears that at 40 °C, the nanohybrid retained its original activity, while the HRP lost 66% of its catalytic activity compared to HRP at room temperature. Further increase in temperature led to even more drastic loss of HRP activity (reduced to almost 31% at 60 °C and further), while AuNP-pSi showed activity retention of 75.4, 75, and 64% at 60, 80, and 100 °C, respectively. The loss of the catalytic activity of HRP at high temperatures could be attributed to the destruction of its molecular structure. In general, natural enzymes are vulnerable to environmental conditions, which can result in a reduction in their catalytic activity and stability due to denaturation. (56,57) However, unlike HRP, AuNP-pSi nanohybrids retain higher catalytic activity after incubation at a broader range of temperatures 40–100 °C, indicating a high-temperature tolerance. The findings strongly indicate that the AuNP-pSi nanohybrid demonstrates remarkable robustness, rendering it well suited for deployment in challenging or harsh environments. The relatively low loss of activity of the AuNP-pSi nanohybrid could be attributed to oxidation of the pSi surface, which eventuates into lower Au3+ reduction and AuNPs on its surface. (40) For AuNP-pSi nanohybrids, the storage stability was evaluated for up to 12 weeks. At set time points, the nanohybrid was activated by mixing the two components in optimal ratios from previous experiments, and catalytic activity was assessed using the TMB oxidation process. The TMB oxidation data revealed minimal apparent loss (around 2%) of activity over the 12-week period (Figure 3h) with close to 98% activity retention for this period. These results signify the retention of the on-demand nanozymatic nature of the AuNP-pSi nanohybrid, allowing for ultralong room temperature storage of the nanozyme compared to the preformed AuNPs. (21) The glucose oxidase (Gox)-like activity of the AuNP-pSi nanohybrid was explored to demonstrate their selective peroxidase-like activity (Figure S5). For this, the AuNP-pSi activity assay was conducted in the presence of glucose instead of H2O2, where the results show an almost 70% lower TMB oxidation as evidenced by the reduction in activity compared to AuNP-pSi in the presence of TMB and H2O2 (Figure S5).
众所周知，天然过氧化物酶（如 HRP）对温度的敏感性很差，一旦暴露在较高的储存温度下，就会迅速失去活性。因此，它们需要冷藏，只能用于 ELISA 检测等高价值应用。因此，我们需要一种耐温性更高的纳米酶。为此，研究人员将 AuNP-pSi 纳米杂交体的两种成分暴露在不同温度（40、60、80 和 100 ℃）下 45 分钟，研究温度对其酶性能的影响。天然 HRP 作为本实验的对比对照。在这些温度下暴露 45 分钟后，发现 AuNP-pSi 和 HRP 都具有 TMB 氧化活性（图 3g）。与室温下的 HRP 相比，纳米杂化物在 40 °C 时保持了原有的活性，而 HRP 则丧失了 66% 的催化活性。温度进一步升高导致 HRP 活性损失更严重（在 60 ℃ 或更高温度下几乎降低到 31%），而 AuNP-pSi 在 60、80 和 100 ℃ 时的活性保持率分别为 75.4%、75% 和 64%。HRP 在高温下丧失催化活性可能是由于其分子结构遭到破坏。一般来说，天然酶易受环境条件的影响，变性会导致其催化活性和稳定性降低。(56,57) 然而，与 HRP 不同的是，AuNP-pSi 纳米混合物在 40-100 °C 的更大温度范围内培养后仍能保持较高的催化活性，这表明其具有耐高温性。 研究结果有力地表明，AuNP-pSi 纳米杂化物具有卓越的稳健性，非常适合在具有挑战性的恶劣环境中使用。AuNP-pSi 纳米杂化物的活性损失相对较低，这可能是由于 pSi 表面被氧化，最终导致 Au3+ 还原和 AuNPs 在其表面的减少。(40) 对于 AuNP-pSi 纳米杂化物，评估了长达 12 周的储存稳定性。在设定的时间点，按先前实验中的最佳比例混合两种成分，激活纳米杂化物，并使用 TMB 氧化过程评估催化活性。TMB 氧化数据显示，在 12 周的时间里，活性的明显损失极小（约 2%）（图 3h），活性保持率接近 98%。这些结果表明，AuNP-pSi 纳米杂交体保留了按需纳米酶的性质，与预制的 AuNPs 相比，纳米酶可以在室温下超长储存。(21) 探索了 AuNP-pSi 纳米杂交体的葡萄糖氧化酶（Gox）样活性，以证明其选择性过氧化物酶样活性（图 S5）。为此，在葡萄糖而不是 H2O2 的存在下进行了 AuNP-pSi 活性测定、结果表明，在有 TMB 和 H2O2 的情况下，与 AuNP-pSi 相比，TMB 氧化率降低了近 70%（图 S5）。
众所周知，天然过氧化物酶（如 HRP）对温度的敏感性很差，一旦暴露在较高的储存温度下，就会迅速失去活性。因此，它们需要冷藏，只能用于 ELISA 检测等高价值应用。因此，我们需要一种耐温性更高的纳米酶。为此，研究人员将 AuNP-pSi 纳米杂交体的两种成分暴露在不同温度（40、60、80 和 100 ℃）下 45 分钟，研究温度对其酶性能的影响。天然 HRP 作为本实验的对比对照。在这些温度下暴露 45 分钟后，发现 AuNP-pSi 和 HRP 都具有 TMB 氧化活性（图 3g）。与室温下的 HRP 相比，纳米杂化物在 40 °C 时保持了原有的活性，而 HRP 则丧失了 66% 的催化活性。温度进一步升高导致 HRP 活性损失更严重（在 60 ℃ 或更高温度下几乎降低到 31%），而 AuNP-pSi 在 60、80 和 100 ℃ 时的活性保持率分别为 75.4%、75% 和 64%。HRP 在高温下丧失催化活性可能是由于其分子结构遭到破坏。一般来说，天然酶易受环境条件的影响，变性会导致其催化活性和稳定性降低。(56,57) 然而，与 HRP 不同的是，AuNP-pSi 纳米混合物在 40-100 °C 的更大温度范围内培养后仍能保持较高的催化活性，这表明其具有耐高温性。 研究结果有力地表明，AuNP-pSi 纳米杂化物具有卓越的稳健性，非常适合在具有挑战性的恶劣环境中使用。AuNP-pSi 纳米杂化物的活性损失相对较低，这可能是由于 pSi 表面被氧化，最终导致 Au3+ 还原和 AuNPs 在其表面的减少。(40) 对于 AuNP-pSi 纳米杂化物，评估了长达 12 周的储存稳定性。在设定的时间点，按先前实验中的最佳比例混合两种成分，激活纳米杂化物，并使用 TMB 氧化过程评估催化活性。TMB 氧化数据显示，在 12 周的时间里，活性的明显损失极小（约 2%）（图 3h），活性保持率接近 98%。这些结果表明，AuNP-pSi 纳米杂交体保留了按需纳米酶的性质，与预制的 AuNPs 相比，纳米酶可以在室温下超长储存。(21) 探索了 AuNP-pSi 纳米杂交体的葡萄糖氧化酶（Gox）样活性，以证明其选择性过氧化物酶样活性（图 S5）。为此，在葡萄糖而不是 H2O2 的存在下进行了 AuNP-pSi 活性测定、结果表明，在有 TMB 和 H2O2 的情况下，与 AuNP-pSi 相比，TMB 氧化率降低了近 70%（图 S5）。
3.3. Steady-State Kinetics for AuNP-pSi Nanohybrids
3.3.AuNP-pSi 纳米杂化的稳态动力学
The steady-state kinetics were studied to further understand the peroxidase-like nanozyme activity of AuNP-pSi. The kinetic studies were carried out by altering the concentration of H2O2 (100–1000 mM) at a constant concentration of TMB (1000 μM) and vice versa for 700 mM H2O2 at varying TMB (100–1000 μM) concentration, a process previously utilized for nanozymes and natural peroxidase assessment. (58) The kinetic parameters were calculated using the initial rate method. (59,60) The value of ε = 39,000 M–1 cm–1 (at 652 nm) for the oxidized product of TMB was employed to convert the absorbance values to the relevant concentration using the Beer–Lambert law. (61) A typical Michaelis–Menten-like curve was attained for both H2O2 (Figure 4a) and TMB (Figure 4b) within the relevant concentration range. The data were aligned with the Michaelis–Menten kinetic model (eq 1) using a nonlinear least-squares fitting method to determine the catalytic parameters Km and Vmax, respectively. (51) Additionally, the Km and Vmax were also determined using the Lineweaver–Burk double-reciprocal plot (1/velocity [V0] versus 1/substrate concentration [S]) (62) (Figure 4c,d) for H2O2 and TMB, respectively. As shown in Figure 4a,b, as the concentration of both H2O2 and TMB increased, the absorbance values at 652 nm also increased (represented as velocity). At H2O2 concentrations up to 1000 mM or TMB concentrations up to 1000 μM, there was no inhibition for the AuNP-pSi catalyzed process, indicating that AuNP-pSi exhibits sustained catalytic activity even at very high H2O2 or TMB concentrations. Accordingly, we adopted the concentrations of H2O2 and TMB as 700 mM and 1000 μM, respectively, for successive experiments. Km is an indication of an enzyme’s affinity for its substrate; a lower Km value suggests a higher affinity between the two. The Km, Vmax, and catalytic efficiency (Kcat) values were calculated to be 0.70 mM, 0.55 × 10–8 MS–1, and 7.86 × 10–9 S–1 for H2O2, and 1.92 mM, 0.37 × 10–8 MS–1, and 3.7 × 10–6 S–1 for TMB, respectively. The findings are summarized in Table S1 and extensively compared to previously published peroxidase mimetic AuNPs and natural HRP. These data suggest that the AuNP-pSi nanohybrids can be useful for biological assays where the presence of excess H2O2 may interfere with the analysis as in living cells.
研究了稳态动力学，以进一步了解 AuNP-pSi 的过氧化物酶样纳米酶活性。动力学研究是通过改变 H2O2（100-1000 mM），TMB（1000 μM）浓度不变；反之亦然，700 mM H2O2 ，TMB（100-1000 μM）浓度变化、这种方法以前曾用于纳米酶和天然过氧化物酶的评估。(58) 动力学参数采用初始速率法计算。(59,60) TMB 氧化产物的ε=39,000 M-1 cm-1 （652 纳米波长），利用比尔-朗伯定律将吸光度值转换为相关浓度。(61) 在相关浓度范围内，H2O2 (图 4a)和 TMB (图 4b)都达到了典型的迈克尔-门顿曲线。使用非线性最小二乘拟合方法将数据与 Michaelis-Menten 动力学模型（eq 1）进行比对，分别确定了催化参数 Km 和 Vmax 。 (51) 此外、Km 和 Vmax 也是用 Lineweaver-Burk 双倒数图（1/速度 [V0] 与 1/底物浓度 [S] 的关系）(62) （图 4c、d）分别表示 H2O2 和 TMB。如图 4a、b 所示，随着 H2O2 和 TMB 浓度的增加，652 纳米波长处的吸光度值也随之增加（以速度表示）。当 H2O2 浓度达到 1000 mM 或 TMB 浓度达到 1000 μM 时，AuNP-pSi 催化过程没有受到抑制、这表明即使在很高的 H2O2 或 TMB 浓度下，AuNP-pSi 也能表现出持续的催化活性。因此，我们采用 H2O2 和 TMB 的浓度分别为 700 mM 和 1000 μM 进行连续实验。Km 表示酶对底物的亲和力；Km 值越低，表明两者之间的亲和力越高。经计算，Km, Vmax 和催化效率（Kcat ）值分别为 0.70 mM、0.55 × 10-8 MS-1 和 7.86 × 10-9 S-1 H2O2, 和 1.92 mM, 0.TMB 分别为 37 × 10-8 MS-1 和 3.7 × 10-6 S-1 。表 S1 总结了这些研究结果，并与之前发表的过氧化物酶模拟 AuNPs 和天然 HRP 进行了广泛比较。这些数据表明，AuNP-pSi 纳米混合物可用于生物检测，因为在生物检测中，过量的 H2O2 可能会干扰分析，就像在活细胞中一样。
研究了稳态动力学，以进一步了解 AuNP-pSi 的过氧化物酶样纳米酶活性。动力学研究是通过改变 H2O2（100-1000 mM），TMB（1000 μM）浓度不变；反之亦然，700 mM H2O2 ，TMB（100-1000 μM）浓度变化、这种方法以前曾用于纳米酶和天然过氧化物酶的评估。(58) 动力学参数采用初始速率法计算。(59,60) TMB 氧化产物的ε=39,000 M-1 cm-1 （652 纳米波长），利用比尔-朗伯定律将吸光度值转换为相关浓度。(61) 在相关浓度范围内，H2O2 (图 4a)和 TMB (图 4b)都达到了典型的迈克尔-门顿曲线。使用非线性最小二乘拟合方法将数据与 Michaelis-Menten 动力学模型（eq 1）进行比对，分别确定了催化参数 Km 和 Vmax 。 (51) 此外、Km 和 Vmax 也是用 Lineweaver-Burk 双倒数图（1/速度 [V0] 与 1/底物浓度 [S] 的关系）(62) （图 4c、d）分别表示 H2O2 和 TMB。如图 4a、b 所示，随着 H2O2 和 TMB 浓度的增加，652 纳米波长处的吸光度值也随之增加（以速度表示）。当 H2O2 浓度达到 1000 mM 或 TMB 浓度达到 1000 μM 时，AuNP-pSi 催化过程没有受到抑制、这表明即使在很高的 H2O2 或 TMB 浓度下，AuNP-pSi 也能表现出持续的催化活性。因此，我们采用 H2O2 和 TMB 的浓度分别为 700 mM 和 1000 μM 进行连续实验。Km 表示酶对底物的亲和力；Km 值越低，表明两者之间的亲和力越高。经计算，Km, Vmax 和催化效率（Kcat ）值分别为 0.70 mM、0.55 × 10-8 MS-1 和 7.86 × 10-9 S-1 H2O2, 和 1.92 mM, 0.TMB 分别为 37 × 10-8 MS-1 和 3.7 × 10-6 S-1 。表 S1 总结了这些研究结果，并与之前发表的过氧化物酶模拟 AuNPs 和天然 HRP 进行了广泛比较。这些数据表明，AuNP-pSi 纳米混合物可用于生物检测，因为在生物检测中，过量的 H2O2 可能会干扰分析，就像在活细胞中一样。
Figure 4 图 4
Figure 4. Steady-state kinetic study of AuNP-pSi nanozymes. The reaction rate was tested by tuning the concentrations of (a) H2O2 and (b) TMB. (c) The Lineweaver–Burk plot obtained by altering the concentration of H2O2 (100–1000 mM) with a fixed amount of TMB (1000 μM). (d) The Lineweaver–Burk plot obtained by varying the concentration of TMB (100–1000 μM) with a fixed amount of H2O2 (700 mM). All experiments were carried out in 0.2 M NaOAc buffer (pH 3.5) at 40 °C, and the absorbance was measured at 652 nm. The error bars depict the standard error obtained from three replicates of the measurements.
图 4：AuNP-pSi 纳米酶的稳态动力学研究AuNP-pSi 纳米酶的稳态动力学研究。通过调节 (a) H2O2 和 (b) TMB 的浓度来测试反应速率。(c) 通过改变 H2O2 的浓度（100-1000 mM）和固定量的 TMB（1000 μM）得到的 Lineweaver-Burk 图。(d) 改变 TMB 的浓度（100-1000 μM）与固定量的 H2O2 (700 mM)，得到的 Lineweaver-Burk 图。所有实验均在 0.2 M NaOAc 缓冲液（pH 3.5）中进行，温度为 40 °C，吸光度在 652 nm 处测量。误差条表示三次重复测量的标准误差。
3.4. AuNP-pSi Nanohybrids for Homocysteine Detection
3.4.用于检测同型半胱氨酸的 AuNP-pSi 纳米混合物
After thorough investigation of the on-demand activatable nature and performance of the AuNP-pSi nanozyme, as a proof of concept, their use in colorimetric detection of a biothiol was demonstrated. For this, AuNP-pSi was formed and centrifuged to remove the unreacted gold ions, which was then incubated with various concentrations of Hcy for 2 h. Subsequently, 700 mM H2O2 and 1000 μM TMB were added and allowed to complete the reaction for a further 30 min at 40 °C before taking the digital photographs or recording the absorption at 652 nm. A decrease in TMB oxidation is observed when freshly activated AuNP-pSi is incubated with increasing concentrations of Hcy as evidenced by a decreasing intensity of the indicative blue color in Figure 5a. In Figure 5b, a reduction in absorbance (%) for AuNP-pSi incubated with varying concentrations of Hcy is presented. Interestingly, the AuNP-pSi nanozyme shows a dual linear working range for Hcy in a biphasic calibration curve. Dual-working linear range is a well-documented phenomenon for many types of sensors including nanozyme sensors. (63,64) Typically, as the analyte concentration increases, the sensor surface becomes saturated and the calibration curve shows a plateau. For most sensors, the calibration curve plateauing shows a smooth transition from a linear stage to saturation, whereas the complex chemical interactions on the surface of many other sensors show an abrupt plateauing. This leads to two distinct working ranges, as observed for our AuNP-pSi nanozymes. The LOD from the lower concentration linear working range was determined to be approximately 0.30 μM, and LOQ of 0.90 μM. The reduction in TMB oxidation at increasing concentrations of Hcy could be attributed to capping of the AuNP-pSi nanozyme through the thiol–AuNP interaction. This limits the active surface area of the AuNP-pSi nanozyme available to catalyze the oxidation of TMB. In other words, the underlying mechanism centers on the interaction between AuNPs and thiol groups, predominantly directed by the strong affinity between gold and sulfur atoms, resulting in the formation of a gold–thiolate (Au–S) bond. Recently, there has been a concentrated research effort aimed at understanding how the Au–S interaction can be disrupted in the context of thiol–gold interactions. These studies have employed a combination of experimental and theoretical methods. (65−67) The finding of this sensing experiment successfully demonstrates the application of an on-demand activated AuNP-pSi nanozyme in sensing where long storage and high-temperature stability are demanded by the sensing environments. It is worth noting that the limit of detection of the AuNP-pSi nanozyme was below the requisite detection limits for Hcy assays in human plasma samples (approximately 5–12 μM). (68) Typically, high-performance liquid chromatography and enzyme-linked immunosorbent assay are used for the detection and quantification of biothiols like Hcy in clinical studies. (69) Although these methods are very sensitive and selective, their cost and sample preparation processes are limiting factors in wider biothiol screening. The detection limit for Hcy with the AuNP-pSi nanozyme was 0.30 μM, comparable to the 0.18 μM achieved using a conjugate addition/cyclization sequence for selective and simultaneous fluorescence detection. (70) The performance of AuNP-pSi nanozymes for detection of biothiols is thoroughly compared with traditional HPLC and ELISA-based methods as well as other nanozymes presented in Table S2. The results of the AuNP-pSi nanozyme were compared with those of previously published Au-based nanozymes for homocysteine detection (Table S3).
在对 AuNP-pSi 纳米酶的按需活化性质和性能进行深入研究后，作为概念验证，展示了其在生物硫醇比色检测中的应用。随后，加入 700 mM H2O2 和 1000 μM TMB，在 40 °C 下继续反应 30 分钟，然后拍摄数码照片或记录 652 纳米波长处的吸收。图 5a 中的指示性蓝色强度下降，这表明当新鲜活化的 AuNP-pSi 与浓度越来越高的 Hcy 一起孵育时，TMB 的氧化作用下降。在图 5b中，显示了与不同浓度的 Hcy 一起培养的 AuNP-pSi 的吸光度降低（%）。有趣的是，AuNP-pSi 纳米酶在双相校准曲线中显示出 Hcy 的双线性工作范围。对于包括纳米酶传感器在内的多种类型的传感器来说，双重线性工作范围是一种有据可查的现象。(63,64) 通常情况下，随着被分析物浓度的增加，传感器表面趋于饱和，校准曲线出现高原。对于大多数传感器来说，校准曲线的高原期显示了从线性阶段到饱和的平滑过渡，而许多其他传感器表面的复杂化学相互作用则显示了突然的高原期。这就导致了两个不同的工作范围，正如我们的 AuNP-pSi 纳米酶所观察到的那样。低浓度线性工作范围的 LOD 约为 0.30 μM，LOQ 为 0.90 μM。 随着 Hcy 浓度的增加，TMB 氧化作用减弱，这可能是由于硫醇-AuNP 相互作用对 AuNP-pSi 纳米酶产生了封盖作用。这限制了 AuNP-pSi 纳米酶可用于催化 TMB 氧化的活性表面积。换句话说，其基本机制集中在 AuNP 与硫醇基团之间的相互作用上，主要由金与硫原子之间的强亲和力引导，从而形成金硫酸盐（Au-S）键。最近，人们集中精力研究如何在硫醇-金相互作用的背景下破坏 Au-S 相互作用。这些研究采用了实验和理论相结合的方法。(65-67) 这项传感实验的发现成功地证明了按需激活的 AuNP-pSi 纳米酶在传感环境要求长期储存和高温稳定性的传感中的应用。值得注意的是，AuNP-pSi 纳米酶的检测限低于人体血浆样品中 Hcy 检测所需的检测限（约 5-12 μM）。(68) 临床研究中通常使用高效液相色谱法和酶联免疫吸附法检测和定量 Hcy 等生物硫醇。(69) 虽然这些方法灵敏度高、选择性强，但其成本和样品制备过程是限制更广泛生物硫醇筛选的因素。AuNP-pSi 纳米酶对 Hcy 的检测限为 0.30 μM，与使用共轭物添加/环化序列进行选择性和同步荧光检测所达到的 0.18 μM相当。 (70)Table S2将 AuNP-pSi 纳米酶检测生物硫醇的性能与传统的 HPLC 和 ELISA 方法以及其他纳米酶进行了全面比较。AuNP-pSi 纳米酶的结果与以前发表的检测同型半胱氨酸的金基纳米酶的结果进行了比较（表 S3）。
在对 AuNP-pSi 纳米酶的按需活化性质和性能进行深入研究后，作为概念验证，展示了其在生物硫醇比色检测中的应用。随后，加入 700 mM H2O2 和 1000 μM TMB，在 40 °C 下继续反应 30 分钟，然后拍摄数码照片或记录 652 纳米波长处的吸收。图 5a 中的指示性蓝色强度下降，这表明当新鲜活化的 AuNP-pSi 与浓度越来越高的 Hcy 一起孵育时，TMB 的氧化作用下降。在图 5b中，显示了与不同浓度的 Hcy 一起培养的 AuNP-pSi 的吸光度降低（%）。有趣的是，AuNP-pSi 纳米酶在双相校准曲线中显示出 Hcy 的双线性工作范围。对于包括纳米酶传感器在内的多种类型的传感器来说，双重线性工作范围是一种有据可查的现象。(63,64) 通常情况下，随着被分析物浓度的增加，传感器表面趋于饱和，校准曲线出现高原。对于大多数传感器来说，校准曲线的高原期显示了从线性阶段到饱和的平滑过渡，而许多其他传感器表面的复杂化学相互作用则显示了突然的高原期。这就导致了两个不同的工作范围，正如我们的 AuNP-pSi 纳米酶所观察到的那样。低浓度线性工作范围的 LOD 约为 0.30 μM，LOQ 为 0.90 μM。 随着 Hcy 浓度的增加，TMB 氧化作用减弱，这可能是由于硫醇-AuNP 相互作用对 AuNP-pSi 纳米酶产生了封盖作用。这限制了 AuNP-pSi 纳米酶可用于催化 TMB 氧化的活性表面积。换句话说，其基本机制集中在 AuNP 与硫醇基团之间的相互作用上，主要由金与硫原子之间的强亲和力引导，从而形成金硫酸盐（Au-S）键。最近，人们集中精力研究如何在硫醇-金相互作用的背景下破坏 Au-S 相互作用。这些研究采用了实验和理论相结合的方法。(65-67) 这项传感实验的发现成功地证明了按需激活的 AuNP-pSi 纳米酶在传感环境要求长期储存和高温稳定性的传感中的应用。值得注意的是，AuNP-pSi 纳米酶的检测限低于人体血浆样品中 Hcy 检测所需的检测限（约 5-12 μM）。(68) 临床研究中通常使用高效液相色谱法和酶联免疫吸附法检测和定量 Hcy 等生物硫醇。(69) 虽然这些方法灵敏度高、选择性强，但其成本和样品制备过程是限制更广泛生物硫醇筛选的因素。AuNP-pSi 纳米酶对 Hcy 的检测限为 0.30 μM，与使用共轭物添加/环化序列进行选择性和同步荧光检测所达到的 0.18 μM相当。 (70)Table S2将 AuNP-pSi 纳米酶检测生物硫醇的性能与传统的 HPLC 和 ELISA 方法以及其他纳米酶进行了全面比较。AuNP-pSi 纳米酶的结果与以前发表的检测同型半胱氨酸的金基纳米酶的结果进行了比较（表 S3）。
Figure 5 图 5
Figure 5. Detection of Hcy using AuNP-pSi shown through (a) digital photographs showing a change in the color intensity upon addition of different concentrations of Hcy (1–750 μM) to AuNP-pSi. The drastic reduction in appearance of the bluish-green color indicates the attachment of thiols to Au in nanohybrids that impedes the TMB oxidation reaction. (b) Corresponding reduction in absorbance (at 652 nm) in percentage in relation to the control (AuNP-pSi without Hcy). A greater reduction in absorbance at 652 nm is observed with increasing concentration of Hcy, confirming the visual results from the digital photographs. (c) Detection of Hcy in human serum is shown through reduction in absorbance (at 652 nm) relative to the control (AuNP-pSi without Hcy) for two different concentrations (100 and 250 μM) of Hcy. The Hcy detection performance of AuNP-pSi in human serum was comparable to their detection ability in NaOAc buffer. (d) Selectivity analysis of the AuNP-pSi nanozyme: homocysteine (Hcy), alanine (A), phenylalanine (F), leucine (L), lysine (K), glycine (G), and l-aspartic acid (D). The concentration of each amino acid was100 μM. The results are presented as reduction in absorbance in percentage in relation to the control (AuNP-pSi). All experiments were carried out in NaOAc buffer (pH 3.5) reaction mixtures containing 700 mM H2O2 and 1000 μM TMB, except for experiments involving real samples carried out in human serum. Error bars represent the standard deviation from three independent experiments.
图 5.利用 AuNP-pSi 检测 Hcy，图中（a）数码照片显示了在 AuNP-pSi 中加入不同浓度的 Hcy（1-750 μM）后颜色强度的变化。蓝绿色外观的急剧下降表明硫醇附着在纳米杂交金上，阻碍了 TMB 氧化反应。(b) 与对照组（不含 Hcy 的 AuNP-pSi）相比，吸光度（652 纳米波长）的相应降低百分比。随着 Hcy 浓度的增加，在 652 纳米波长处的吸光度降低幅度更大，这与数码照片的直观结果相吻合。(c) 在两种不同浓度（100 和 250 μM）的 Hcy 作用下，相对于对照组（不含 Hcy 的 AuNP-pSi）的吸光度（652 nm 处）的降低情况显示了人血清中 Hcy 的检测情况。AuNP-pSi 在人血清中的 Hcy 检测性能与其在 NaOAc 缓冲液中的检测能力相当。(d) AuNP-pSi 纳米酶的选择性分析：同型半胱氨酸（Hcy）、丙氨酸（A）、苯丙氨酸（F）、亮氨酸（L）、赖氨酸（K）、甘氨酸（G）和l-天冬氨酸（D）。每种氨基酸的浓度均为 100 μM。结果以相对于对照组（AuNP-pSi）的吸光度降低百分比表示。所有实验均在含有 700 mM H2O2 和 1000 μM TMB 的 NaOAc 缓冲液（pH 3.5）反应混合物中进行，但在人血清中进行的涉及真实样本的实验除外。误差条代表三个独立实验的标准偏差。
The Hcy detection in a real-life sample was verified by conducting a sensing reaction at two different Hcy concentrations, 100 and 250 μM, using human serum as the detection media. The results show that the AuNP-pSi nanohybrid performs equally well in a complex solvent such as human serum as in NaOAc buffer (Figure 5c). The reduction in absorbance (relative to AuNP-pSi control without Hcy) for Hcy prepared in human serum was comparable to that of the Hcy sample in NaOAc buffer for both of the tested concentrations. The results indicate the strong biothiol detection potential of AuNP-pSi in real-patient samples.
通过使用人血清作为检测介质，在两种不同的 Hcy 浓度（100 和 250 μM）下进行传感反应，验证了在实际样品中的 Hcy 检测能力。结果表明，AuNP-pSi 纳米杂化物在人血清等复杂溶剂中和在 NaOAc 缓冲液中的表现同样出色（图 5c）。在人血清中制备的 Hcy 的吸光度降低率（相对于不含 Hcy 的 AuNP-pSi 对照）与 NaOAc 缓冲液中的 Hcy 样品的吸光度降低率（相对于 NaOAc 缓冲液中的 Hcy 样品）相当。结果表明，AuNP-pSi 在实际患者样本中具有很强的生物硫醇检测潜力。
通过使用人血清作为检测介质，在两种不同的 Hcy 浓度（100 和 250 μM）下进行传感反应，验证了在实际样品中的 Hcy 检测能力。结果表明，AuNP-pSi 纳米杂化物在人血清等复杂溶剂中和在 NaOAc 缓冲液中的表现同样出色（图 5c）。在人血清中制备的 Hcy 的吸光度降低率（相对于不含 Hcy 的 AuNP-pSi 对照）与 NaOAc 缓冲液中的 Hcy 样品的吸光度降低率（相对于 NaOAc 缓冲液中的 Hcy 样品）相当。结果表明，AuNP-pSi 在实际患者样本中具有很强的生物硫醇检测潜力。
The selectivity of the AuNP-pSi nanozyme toward Hcy was examined by introducing various amino acids (including alanine (A), phenylalanine (F), leucine (L), lysine (K), glycine (G), and l-aspartic acid (D)) to the reaction mixture and evaluating the results. As shown in Figure 5d, only Hcy showed a dramatic decrease in the absorbance compared to the control (AuNP-pSi), around 61%, whereas other amino acids did not show much decrease (3, 6, 3, 5, 8, and 2% for A, F, L, K, G, and D, respectively). However, there are several other biothiols, which can interact with the AuNP-pSi nanozyme impacting their selectivity toward Hcy. As previously stated, this could be attributed to capping of the AuNP-pSi through thiol–AuNP interaction and the absence of a thiol group in these amino acids that leads to lower interaction and sustained color generation.
通过向反应混合物中引入各种氨基酸（包括丙氨酸 (A)、苯丙氨酸 (F)、亮氨酸 (L)、赖氨酸 (K)、甘氨酸 (G) 和 l- 天冬氨酸 (D)）并评估结果，检验了 AuNP-pSi 纳米酶对 Hcy 的选择性。如图 5d所示，与对照组（AuNP-pSi）相比，只有 Hcy 的吸光度急剧下降，降幅约为 61%，而其他氨基酸的降幅并不大（A、F、L、K、G 和 D 的降幅分别为 3%、6%、3%、5%、8% 和 2%）。不过，还有几种生物硫醇会与 AuNP-pSi 纳米酶相互作用，影响其对 Hcy 的选择性。如前所述，这可能是由于 AuNP-pSi 通过硫醇-AuNP 相互作用而被封盖，以及这些氨基酸中没有硫醇基团，从而导致较低的相互作用和持续的颜色生成。
通过向反应混合物中引入各种氨基酸（包括丙氨酸 (A)、苯丙氨酸 (F)、亮氨酸 (L)、赖氨酸 (K)、甘氨酸 (G) 和 l- 天冬氨酸 (D)）并评估结果，检验了 AuNP-pSi 纳米酶对 Hcy 的选择性。如图 5d所示，与对照组（AuNP-pSi）相比，只有 Hcy 的吸光度急剧下降，降幅约为 61%，而其他氨基酸的降幅并不大（A、F、L、K、G 和 D 的降幅分别为 3%、6%、3%、5%、8% 和 2%）。不过，还有几种生物硫醇会与 AuNP-pSi 纳米酶相互作用，影响其对 Hcy 的选择性。如前所述，这可能是由于 AuNP-pSi 通过硫醇-AuNP 相互作用而被封盖，以及这些氨基酸中没有硫醇基团，从而导致较低的相互作用和持续的颜色生成。
4. Conclusions 4.结论
Click to copy section link
点击复制章节链接Section link copied!
点击复制章节链接Section link copied!
In summary, an on-demand activatable and ultrastable AuNP-pSi nanohybrid system was prepared, which possessed peroxidase-like enzymatic activity. According to our investigation, the AuNP-pSi nanozyme mimics the enzyme-co-factor relationships of natural enzymes where the activity of the enzyme can be modulated by the cofactor, which is essential for a complete control over biological process and undesired enzymatic reaction. Similarly, the on-demand activation of the AuNP-pSi nanohybrid has potential to lead to new opportunities for colorimetric sensing under sensitive and physicochemically challenging conditions. The results demonstrated that AuNP-pSi retained almost 65% of enzymatic activity even after incubation at 100 °C and maintained around 98% activity when stored at room temperature for 12 weeks. The Michaelis–Menten and Lineweaver–Burk models for the enzyme-catalyzed H2O2/TMB reaction at 40 °C resulted in the Michaelis–Menten constant and maximum velocity parameters of 1.92 mM and 0.37 × 10–8 MS–1 for TMB and 0.70 mM and 0.55 × 10–8 MS–1 for H2O2, respectively. The AuNP-pSi nanohybrid facilitated the detection of Hcy in the range of 1–750 μM with an LOD of 0.30 μM.
综上所述，我们制备了一种可按需激活且超稳定的 AuNP-pSi 纳米杂交系统，该系统具有类似过氧化物酶的酶活性。根据我们的研究，AuNP-pSi 纳米酶模拟了天然酶的酶-co 因子关系，即酶的活性可受辅助因子的调节，这对于完全控制生物过程和不良酶促反应至关重要。同样，AuNP-pSi 纳米杂化物的按需活化也有可能为在敏感和具有物理化学挑战性的条件下进行比色传感带来新的机遇。研究结果表明，AuNP-pSi 在 100 °C 下孵育后仍能保持近 65% 的酶活性，在室温下保存 12 周后仍能保持约 98% 的活性。在 40 °C下酶催化 H2O2/TMB 反应的 Michaelis-Menten 和 Lineweaver-Burk 模型得出 Michaelis-Menten 常量和最大速度参数分别为 1.92 mM 和 0.37 × 10-8 MS-1 TMB 和 0.70 mM 和 0.55 × 10-8 MS-1 分别为 H2O2 。AuNP-pSi 纳米杂交有助于检测 1-750 μM 范围内的 Hcy，检测限为 0.30 μM。
综上所述，我们制备了一种可按需激活且超稳定的 AuNP-pSi 纳米杂交系统，该系统具有类似过氧化物酶的酶活性。根据我们的研究，AuNP-pSi 纳米酶模拟了天然酶的酶-co 因子关系，即酶的活性可受辅助因子的调节，这对于完全控制生物过程和不良酶促反应至关重要。同样，AuNP-pSi 纳米杂化物的按需活化也有可能为在敏感和具有物理化学挑战性的条件下进行比色传感带来新的机遇。研究结果表明，AuNP-pSi 在 100 °C 下孵育后仍能保持近 65% 的酶活性，在室温下保存 12 周后仍能保持约 98% 的活性。在 40 °C下酶催化 H2O2/TMB 反应的 Michaelis-Menten 和 Lineweaver-Burk 模型得出 Michaelis-Menten 常量和最大速度参数分别为 1.92 mM 和 0.37 × 10-8 MS-1 TMB 和 0.70 mM 和 0.55 × 10-8 MS-1 分别为 H2O2 。AuNP-pSi 纳米杂交有助于检测 1-750 μM 范围内的 Hcy，检测限为 0.30 μM。
Supporting Information 辅助信息
Click to copy section link
点击复制章节链接Section link copied!
点击复制章节链接Section link copied!
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsanm.3c05677.
辅助信息可在https://pubs.acs.org/doi/10.1021/acsanm.3c05677免费获取。
DLS data for pSi and different AuNP-pSi nanohybrids, UV–vis absorbance of pSi and different AuNP-pSi nanohybrids, XRD for pSi and AuNP-pSi nanohybrids, digital photographs of TMB catalyzed by AuNP-pSi nanohybrids, additional details for mechanism of AuNP formation and their catalytic activity, assessment of glucose oxidase activity of AuNP-pSi, comparison of AuNP-pSi with other nanozymes, natural peroxidase, and comparison of biothiol detection performance of AuNP-pSi nanohybrids with standard methods (PDF)
pSi 和不同 AuNP-pSi 纳米混合物的 DLS 数据、pSi 和不同 AuNP-pSi 纳米混合物的紫外-可见吸收率、pSi 和 AuNP-pSi 纳米混合物的 XRD、AuNP-pSi 纳米混合物催化 TMB 的数码照片、AuNP 形成机制及其催化活性的更多细节、评估 AuNP-pSi 的葡萄糖氧化酶活性、AuNP-pSi 与其他纳米酶和天然过氧化物酶的比较，以及 AuNP-pSi 纳米杂交体的生物硫醇检测性能与标准方法的比较 (PDF)Description of supplementary video: a stepwise on-demand activation of AuNP-pSi peroxidase-mimicking nanozyme and their ability to oxidize TMB in the presence of H2O2 (MP4)
补充视频描述：在 H2O2 （MP4 ）存在的情况下，按需逐步激活 AuNP-pSi 过氧化物酶模拟纳米酶及其氧化 TMB 的能力。
Terms & Conditions 条款和条件
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.
大多数电子版辅助信息文件无需订阅 ACS Web Editions 即可获得。此类文件可按文章下载，供研究使用（如果相关文章链接了公共使用许可，则该许可可能允许其他用途）。如需其他用途，可通过 RightsLink 许可系统向 ACS 申请许可：http://pubs.acs.org/page/copyright/permissions.html。
Author Information 作者信息
Click to copy section link
点击复制章节链接Section link copied!
点击复制章节链接Section link copied!
- Kourosh Kalantar-Zadeh - School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW 2006, Australia;
https://orcid.org/0000-0001-6109-132X;
Kourosh Kalantar-Zadeh - School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW 2006, Australia; https://orcid.org/0000-0001-6109-132X; - Tushar Kumeria - School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, Australia; Australian Centre for Nanomedicine, University of New South Wales, Sydney, NSW 2052, Australia;https://orcid.org/0000-0003-3351-7148;
Tushar Kumeria - School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, Australia；Australian Centre for Nanomedicine, University of New South Wales, Sydney, NSW 2052, Australia; https：//orcid.org/0000-0003-3351-7148;
- Prakriti Siwakoti - School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, Australia;https://orcid.org/0000-0003-0055-6095
Acknowledgments 致谢
Click to copy section link
点击复制章节链接Section link copied!
点击复制章节链接Section link copied!
T.K. acknowledges the support from the National Health and Medical Research Council of Australia (NHMRC) for Early Career Fellowship (GNT1143296) and the University of New South Wales for support and Scientia Grant. The authors also thank the Australian Government for the Research Training Program (RTP) Scholarship awarded to A. Saeed.
T.K.感谢澳大利亚国家健康与医学研究委员会（NHMRC）提供的早期职业研究奖学金（GNT1143296）以及新南威尔士大学提供的支持和科学补助金。作者还感谢澳大利亚政府为 A. Saeed 颁发的研究培训计划（RTP）奖学金。
References 参考资料
Click to copy section link
点击复制章节链接Section link copied!
点击复制章节链接Section link copied!
This article references
70 other publications.
这篇文章参考了 70 篇其他出版物。
- 1Lu, M.; Wang, C.; Ding, Y.; Peng, M.; Zhang, W.; Li, K.; Wei, W.; Lin, Y. Fe–N/C single-atom catalysts exhibiting multienzyme activity and ROS scavenging ability in cells. Chem. Commun. 2019, 55 (96), 14534– 14537, DOI: 10.1039/C9CC07408BGoogle Scholar 谷歌学者1https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitFegsLnN&md5=194d8c18b204aa78808a254e7f09dc99Fe-N/C single-atom catalysts exhibiting multienzyme activity and ROS scavenging ability in cellsLu, Mingju; Wang, Chao; Ding, Yongqi; Peng, Meihong; Zhang, Wang; Li, Kai; Wei, Wei; Lin, YuqingChemical Communications (Cambridge, United Kingdom) (2019), 55 (96), 14534-14537CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)Fe-N/C single atom catalysts (SACs) exhibit peroxidase-like, oxidase-like, catalase-like, and glutathione peroxidase-like activity. Fe-N/C SACs are successfully applied to control the intracellular H2O2 level. This study not only explores the types of SACs mimicking enzymes but also provides opportunities for SACs in biomedical and other bioengineering applications.
1Lu, M.；Wang, C.; Ding, Y.; Peng, M.; Zhang, W.; Li, K.; Wei, W.; Lin, Y. Fe-N/C 单原子催化剂在细胞中表现出多酶活性和 ROS 清除能力。Chem.Commun. 2019, 55 (96), 14534-14537, DOI： 10.1039/C9CC07408BGoogle Scholarhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitFegsLnN&md5=194d8c18b204aa78808a254e7f09dc99Fe-N/C single-atom catalysts.dl-uid="36">1Fe-N/C 单原子催化剂在细胞中表现出多酶活性和清除 ROS 的能力Lu、王超 丁永强Wang, Chao; Ding, Yongqi; Peng, Meihong; Zhang, Wang; Li, Kai; Wei, Wei; Lin, YuqingChemical Communications (Cambridge, United Kingdom)2019), 55 (96）、 14534-14537CODEN: CHCOFS； ISSN:1359-7345. (英国皇家化学学会)Fe-N/C单原子催化剂（SAC）具有过氧化物酶样、氧化酶样、过氧化氢酶样和谷胱甘肽过氧化物酶样活性。 Fe-N/C SACs 成功地应用于控制细胞内 H2O2 水平。 这项研究不仅探索了模拟酶的 SACs 的类型，而且为 SACs 在生物医学和其他生物工程领域的应用提供了机会。 - 2Wolfe, M. G.; Ali, M. M.; Brennan, J. D. Enzymatic litmus test for selective colorimetric detection of C–C single nucleotide polymorphisms. Anal. Chem. 2019, 91 (7), 4735– 4740, DOI: 10.1021/acs.analchem.9b00235Google Scholar 谷歌学者2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXkslentrw%253D&md5=170de6f8aac56066e74ca06236b63b73Enzymatic litmus test for selective colorimetric detection of C-C single nucleotide polymorphismsWolfe, Michael G.; Ali, M. Monsur; Brennan, John D.Analytical Chemistry (Washington, DC, United States) (2019), 91 (7), 4735-4740CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)A paper based litmus test has been developed using modulation of urease enzyme activity for detection of C-C mismatch single nucleotide polymorphisms (SNPs) by the naked eye. Urease is first inactivated with silver ions and printed onto paper microzones. Addn. of DNA contg. C-C mismatches reactivates urease via binding of Ag(I), allowing restoration of urease activity, hydrolysis of urea to produce ammonia, and an increase in pH, which is monitored colorimetrically using a pH indicator with a limit of detection of 11 nM DNA in 40 min. The assay system is easy to use, portable, and stable for at least 30 days at ambient temp. To assess the versatility and practical application of the paper sensor, we used it to identify a G > C transversion present in human genomic DNA from a ductal carcinoma cell line, a mutation commonly found in breast cancer. We believe this new assay system has the potential to be a low-cost method for rapidly identifying DNA with the C-C mismatch SNP as a means of cancer screening in resource-limited areas.
2Wolfe, M. G.; Ali, M. M.G.; Ali, M. M.; Brennan, J. D. 选择性比色检测 C-C 单核苷酸多态性的酶石蕊试验。Anal.Chem. 2019, 91 (7)、 4735- 4740, ；DOI： 10.1021/acs.analchem.9b00235Google Scholar2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXkslentrw%253D&md5=170de6f8aac56066e74ca06236b63b73选择性比色检测 C-C 单核苷酸多态性的酶石蕊试剂Wolfe、Michael G.Ali, M. Monsur; Brennan, John D.分析化学（美国华盛顿特区）2019), 91 (7）、 4735-4740CODEN: ANCHAM； ISSN:0003-2700. (美国化学学会)我们开发了一种基于纸张的石蕊试纸，利用调节尿素酶的活性，通过肉眼检测 C-C 错配单核苷酸多态性（SNP）。 首先用银离子灭活尿素酶，然后将其印制在纸微区上。 然后加入 DNA contg.C-C错配的 DNA 通过与 Ag(I) 结合使脲酶重新活化，从而恢复脲酶的活性，水解尿素产生氨，pH 值升高，使用 pH 指示剂以比色法监测 pH 值，40 分钟内 DNA 的检测限为 11 nM。 该检测系统使用方便，便于携带，在环境温度下至少可稳定工作 30 天。 为了评估纸传感器的多功能性和实际应用，我们用它来鉴定乳腺导管癌细胞系的人类基因组 DNA 中的 G > C 转换，这是乳腺癌中常见的一种突变。 我们相信，这种新的检测系统有可能成为一种低成本方法，用于快速鉴定带有 C-C 错配 SNP 的 DNA，作为资源有限地区癌症筛查的一种手段。 - 3Whitesides, G. M.; Wong, C. H. Enzymes as catalysts in synthetic organic chemistry [new synthetic methods (53)]. Angew. Chem., Int. Ed. 1985, 24 (8), 617– 638, DOI: 10.1002/anie.198506173
3Whitesides, G. M.; Wong, C. H. Enzymes as catalysts in synthetic organic chemistry [new synthetic methods (53)].Angew.Chem.Ed. 1985, 24 (8)、 617- 638, ；DOI： 10.1002/anie.198506173。 - 4Apetrei, I.; Rodriguez-Mendez, M.; Apetrei, C.; De Saja, J. Enzyme sensor based on carbon nanotubes/cobalt (II) phthalocyanine and tyrosinase used in pharmaceutical analysis. Sens. Actuators, B 2013, 177, 138– 144, DOI: 10.1016/j.snb.2012.10.131Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsFKrs78%253D&md5=0434e56a1841668edc8a8048ba888e0eEnzyme sensor based on carbon nanotubes/cobalt(II) phthalocyanine and tyrosinase used in pharmaceutical analysisApetrei, I. M.; Rodriguez-Mendez, M. L.; Apetrei, C.; de Saja, J. A.Sensors and Actuators, B: Chemical (2013), 177 (), 138-144CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A multicomponent enzyme sensor was used to evaluate phenolic compds. in plant-based pharmaceutical formulations. Multiwall carbon nanotubes were used as carbonaceous material used for the electrode construction. Cobalt phthalocyanine was used as electron mediator and tyrosinase as biocatalyst. The enzyme sensor performance was analyzed by cyclic voltammetry and amperometry in model soln. of catechol and catechin. The cyclic voltammograms and the amperometric curves show an intense cathodic peak depending on the concn. of thephenolic compd. The cathodic peak was attributed to the redn. of enzymically produced o-quinone at the enzyme sensor surface. For the model phenolics analyzed, the kinetics of the enzymic reaction fitted into a Michaelis-Menten type kinetics, as confirmed by the h parameter close to 1 obtained from the Hill's plot. The detection limits were in the range of 1.66-6.32 μM demonstrating good quality performances of the enzyme sensor. Pharmaceutical samples were analyzed with multi-component biocomposite enzyme sensor to evaluate its real feasibility in pharmaceutical anal.
- 5Zhang, X.; Li, G.; Wu, D.; Li, X.; Hu, N.; Chen, J.; Chen, G.; Wu, Y. Recent progress in the design fabrication of metal-organic frameworks-based nanozymes and their applications to sensing and cancer therapy. Biosens. Bioelectron. 2019, 137, 178– 198, DOI: 10.1016/j.bios.2019.04.061Google Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXps1Whur0%253D&md5=c096587e6946e163079dd994b28ec08fRecent progress in the design fabrication of metal-organic frameworks-based nanozymes and their applications to sensing and cancer therapyZhang, Xianlong; Li, Guoliang; Wu, Di; Li, Xiuling; Hu, Na; Chen, Jian; Chen, Guang; Wu, YongningBiosensors & Bioelectronics (2019), 137 (), 178-198CODEN: BBIOE4; ISSN:0956-5663. (Elsevier B.V.)The nanomaterials with enzyme-like catalytic activity, named as nanozymes, have aroused wide research interest owing to their striking merits. Metal-org. frameworks (MOFs) have showed great prospect in the construction of novel nanozymes. In this review, firstly, we summarize the most recent contributions in the design construction of the MOFs-based nanozymes. Then, we conc. our attention on their applications in the fields of sensing and cancer therapies. According to the design strategies, we categorized MOFs-based nanozymes into four classes for review (i.e. pristine MOFs, MOFs with modification, MOFs-based nanocomposites, and MOF derivs.). Meanwhile, the emerging and fascinating 2D MOFs-based nanozymes were also reviewed. A variety of novel applications are also discussed, including nanozymes catalytic mediated signal amplification in sensing applications (e.g. colorimetric sensing, fluorescent sensing, chemiluminescent sensing, electrochem. sensing, and surface-enhanced Raman scattering (SERS)), and nanozymes catalytic mediated cancer therapy (i.e. cancer-starvation therapy, enhancing photodynamic therapy, and cancer-starvation and PDT synergistic therapy). At the end of the article, future opportunities and challenges in this promising research area are tentatively proposed.
- 6Lin, Y.; Ren, J.; Qu, X. Catalytically active nanomaterials: a promising candidate for artificial enzymes. Acc. Chem. Res. 2014, 47 (4), 1097– 1105, DOI: 10.1021/ar400250zGoogle Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXpt1Krsw%253D%253D&md5=a48acb7b9c00806fb7ec2b689bb207f7Catalytically active nanomaterials: A promising candidate for artificial enzymesLin, Youhui; Ren, Jinsong; Qu, XiaogangAccounts of Chemical Research (2014), 47 (4), 1097-1105CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)A review. Natural enzymes, exquisite biocatalysts mediating every biol. process in living organisms, are able to accelerate the rate of chem. reactions up to 1019-fold for specific substrates and reactions. However, the practical application of enzymes is often hampered by their intrinsic drawbacks, such as low operational stability, sensitivity of catalytic activity to environmental conditions, and high costs in prepn. and purifn. Therefore, the discovery and development of artificial enzymes is highly desired. Recently, the merging of nanotechnol. with biol. has ignited extensive research efforts for designing functional nanomaterials that exhibit various properties intrinsic to enzymes. As a promising candidate for artificial enzymes, catalytically active nanomaterials (nanozymes) show several advantages over natural enzymes, such as controlled synthesis in low cost, tunability in catalytic activities, as well as high stability against stringent conditions. Here, the authors focus on their recent progress in exploring and constructing such nanoparticulate artificial enzymes, including graphene oxide, graphene-hemin nanocomposites, carbon nanotubes, carbon nanodots, mesoporous silica-encapsulated gold nanoparticles, gold nanoclusters, and nanoceria. According to their structural characteristics, these enzyme mimics have been categorized into 3 classes: carbon-based, metal-based, and metal-oxide-based nanomaterials. The authors highlight the important role of catalytic nanomaterials in the fields of biomimetics. First, the authors provide a practical introduction to the identification of these nanozymes, the source of the enzyme-like activities, and the enhancement of activities via rational design and engineering. Then, the authors briefly describe new or enhanced applications of certain nanozymes in biomedical diagnosis, environmental monitoring, and therapeutics. For instance, the authors have successfully used these biomimetic catalysts as colorimetric probes for the detection of cancer cells, nucleic acids, proteins, metal ions, and other small mols. In addn., the authors also introduce 3 exciting advances in the use of efficient modulators on artificial enzyme systems to improve the catalytic performance of existing nanozymes. For example, the authors report that graphene oxide could serve as a modulator to greatly improve the catalytic activity of lysozyme-stabilized gold nanoclusters at neutral pH, which will have great potential for applications in biol. systems. The authors show that, through the incorporation of modulators into artificial enzymes, they can offer a facile but highly effective way to improve their overall catalytic performance or realize catalytic reactions that were not possible in the past. The authors expect that nanozymes with unique properties and functions will attract increasing research interest and lead to new opportunities in various fields of research.
- 7Gao, L.; Zhuang, J.; Nie, L.; Zhang, J.; Zhang, Y.; Gu, N.; Wang, T.; Feng, J.; Yang, D.; Perrett, S.; Yan, X. Intrinsic peroxidase-like activity of ferromagnetic nanoparticles. Nat. Nanotechnol. 2007, 2 (9), 577– 583, DOI: 10.1038/nnano.2007.260Google Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpvVOksLg%253D&md5=c314011a4e43e9bddf51babae3e2df47Intrinsic peroxidase-like activity of ferromagnetic nanoparticlesGao, Lizeng; Zhuang, Jie; Nie, Leng; Zhang, Jinbin; Zhang, Yu; Gu, Ning; Wang, Taihong; Feng, Jing; Yang, Dongling; Perrett, Sarah; Yan, XiyunNature Nanotechnology (2007), 2 (9), 577-583CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)Nanoparticles contg. magnetic materials, such as magnetite (Fe3O4), are particularly useful for imaging and sepn. techniques. As these nanoparticles are generally considered to be biol. and chem. inert, they are typically coated with metal catalysts, antibodies or enzymes to increase their functionality as sepn. agents. Here, we report that magnetite nanoparticles in fact possess an intrinsic enzyme mimetic activity similar to that found in natural peroxidases, which are widely used to oxidize org. substrates in the treatment of wastewater or as detection tools. Based on this finding, we have developed a novel immunoassay in which antibody-modified magnetite nanoparticles provide three functions: capture, sepn. and detection. The stability, ease of prodn. and versatility of these nanoparticles makes them a powerful tool for a wide range of potential applications in medicine, biotechnol. and environmental chem.
- 8Cormode, D. P.; Gao, L.; Koo, H. Emerging biomedical applications of enzyme-like catalytic nanomaterials. Trends Biotechnol. 2018, 36 (1), 15– 29, DOI: 10.1016/j.tibtech.2017.09.006Google Scholar8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhs1CmsL%252FL&md5=d1598eed24ff110e2f14513fd0738eb7Emerging Biomedical Applications of Enzyme-Like Catalytic NanomaterialsCormode, David P.; Gao, Lizeng; Koo, HyunTrends in Biotechnology (2018), 36 (1), 15-29CODEN: TRBIDM; ISSN:0167-7799. (Elsevier Ltd.)A review. Nanomaterials have been developed for many biomedical applications, including medical imaging, drug delivery, and antimicrobial coatings. Intriguingly, nanoparticles can display 'enzyme-like' activity and have been explored as alternatives to natural enzymes in several industrial and energy-related applications. Recently, these catalytic nanomaterials with enzyme-mimetic properties have found new biomedical applications, from biofilm disruption to protection against neurodegeneration and tumor prevention. In this review we focus on recent in vivo studies demonstrating potential therapeutic uses of catalytic nanomaterials. We also provide insights about the relationships between catalytic activity, therapeutic efficacy, and biocompatibility that are crit. for clin. translatability. Finally, we discuss current challenges and future directions for the use of these nanomaterials as novel platforms for the development of sustainable, affordable, and safe therapeutics.
- 9Liu, Q.; Zhang, A.; Wang, R.; Zhang, Q.; Cui, D. A review on metal-and metal oxide-based nanozymes: properties, mechanisms, and applications. Nano–Micro Lett. 2021, 13, 154, DOI: 10.1007/s40820-021-00674-8Google Scholar9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXitFGmu7bK&md5=b6d8f6bb70dbfa231b2bda8b397a948fA review on metal- and metal oxide-based nanozymes: properties, mechanisms, and applicationsLiu, Qianwen; Zhang, Amin; Wang, Ruhao; Zhang, Qian; Cui, DaxiangNano-Micro Letters (2021), 13 (), 154CODEN: NLAEBV; ISSN:2150-5551. (Nano-Micro Letters)A review. Since the ferromagnetic (Fe3O4) nanoparticles were firstly reported to exert enzyme-like activity in 2007, extensive research progress in nanozymes has been made with deep investigation of diverse nanozymes and rapid development of related nanotechnologies. As promising alternatives for natural enzymes, nanozymes have broadened the way toward clin. medicine, food safety, environmental monitoring, and chem. prodn. The past decade has witnessed the rapid development of metal- and metal oxide-based nanozymes owing to their remarkable physicochem. properties in parallel with low cost, high stability, and easy storage. It is widely known that the deep study of catalytic activities and mechanism sheds significant influence on the applications of nanozymes. This review digs into the characteristics and intrinsic properties of metal- and metal oxide-based nanozymes, esp. emphasizing their catalytic mechanism and recent applications in biol. anal., relieving inflammation, antibacterial, and cancer therapy. We also conclude the present challenges and provide insights into the future research of nanozymes constituted of metal and metal oxide nanomaterials.
- 10Masud, M. K.; Na, J.; Younus, M.; Hossain, M. S. A.; Bando, Y.; Shiddiky, M. J.; Yamauchi, Y. Superparamagnetic nanoarchitectures for disease-specific biomarker detection. Chem. Soc. Rev. 2019, 48 (24), 5717– 5751, DOI: 10.1039/C9CS00174CGoogle Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitFCjtb7M&md5=8f9023ce9c12920db1320815abd2ce5aSuperparamagnetic nanoarchitectures for disease-specific biomarker detectionMasud, Mostafa Kamal; Na, Jongbeom; Younus, Muhammad; Hossain, Md. Shahriar A.; Bando, Yoshio; Shiddiky, Muhammad J. A.; Yamauchi, YusukeChemical Society Reviews (2019), 48 (24), 5717-5751CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)A review. The detection of clin. relevant disease-specific biomols., including nucleic acids, circulating tumor cells, proteins, antibodies, and extracellular vesicles, has been indispensable to understand their functions in disease diagnosis and prognosis. Therefore, a biosensor for the robust, ultrasensitive, and selective detection of these low-abundant biomols. in body fluids (blood, urine, and saliva) is emerging in current clin. research. In recent years, nanomaterials, esp. superparamagnetic nanomaterials, have played essential roles in biosensing due to their intrinsic magnetic, electrochem., and optical properties. However, engineered multicomponent magnetic nanoparticle-based current biosensors that offer the advantages of excellent stability in a complex biomatrix; easy and alterable biorecognition of ligands, antibodies, and receptor mols.; and unified point-of-care integration have yet to be achieved. This review introduces the recent advances in superparamagnetic nanostructures for electrochem. and optical biosensing for disease-specific biomarkers. This review emphasizes the synthesis, biofunctionalization, and intrinsic properties of nanomaterials essential for robust, ultrasensitive biosensing. With a particular emphasis on nanostructure-based electrochem. and optical detection of disease-specific biomarkers such as nucleic acids (DNA and RNA), proteins, autoantibodies, and cells, this review also chronicles the needs and challenges of nanoarchitecture-based detection. These summaries provide further insights for researchers to inspire their future work on the development of nanostructures for integrating into biosensing and devices for a broad field of applications in anal. sensing and in clinic.
- 11Lou-Franco, J.; Das, B.; Elliott, C.; Cao, C. Gold nanozymes: from concept to biomedical applications. Nano–Micro Lett. 2021, 13, 10, DOI: 10.1007/s40820-020-00532-zGoogle ScholarThere is no corresponding record for this reference.
- 12Hou, Q.; Zhang, X.; Lin, M.; Dai, Y.; Xia, F. Organic monolayer on gold nanoparticles as hydrolytic nanozymes. Giant 2022, 12, 100122 DOI: 10.1016/j.giant.2022.100122Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XivVCqsL7K&md5=5f65bd89c2182ad801d6094298315a4eOrganic monolayer on gold nanoparticles as hydrolytic nanozymesHou, Qin; Zhang, Xiaojin; Lin, Meihua; Dai, Yu; Xia, FanGiant (2022), 12 (), 100122CODEN: GIANAR; ISSN:2666-5425. (Elsevier Ltd.)Nanozymes are a class of nanomaterials with enzyme-like catalytic properties, which have environmental tolerance and long-term stability. Improving catalytic activity and expanding the variety of nanozymes are the prerequisites to complement or even replace natural enzymes. The assembly of org. monolayer contg. catalytic site on the surface of inorg. nanoparticles is a very effective strategy to improve catalytic activity and expand the variety of nanozymes. Here, we discuss how to construct org. monolayer on the surface of gold nanoparticles, classify the types of org. monolayer, and introduce their applications in nucleic acid hydrolysis and sensing. It is hoped to further promote the research progress of hydrolytic nanozymes.
- 13Wu, J.; Li, S.; Wei, H. Integrated nanozymes: facile preparation and biomedical applications. Chem. Commun. 2018, 54 (50), 6520– 6530, DOI: 10.1039/C8CC01202DGoogle Scholar13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXksFaru7k%253D&md5=b0d42ce465bcdb811c478d571885e90aIntegrated nanozymes: facile preparation and biomedical applicationsWu, Jiangjiexing; Li, Sirong; Wei, HuiChemical Communications (Cambridge, United Kingdom) (2018), 54 (50), 6520-6530CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)A review. Nanozymes have been viewed as the next generation of artificial enzymes due to their low cost, large sp. surface area, and good robustness under extreme conditions. However, the moderate activity and limited selectivity of nanozymes have impeded their usage. To overcome these shortcomings, integrated nanozymes (INAzymes) have been developed by encapsulating two or more different biocatalysts (e.g., natural oxidases and peroxidase mimics) together within confined frameworks. On the one hand, with the assistance of natural enzymes, INAzymes are capable of specifically recognizing targets. On the other hand, nanoscale confinement brought about by integration significantly enhances the cascade reaction efficiency. In this Feature Article, we highlight the newly developed INAzymes, covering from synthetic strategies to versatile applications in biodetection and therapeutics. Moreover, it is predicted that INAzymes with superior activities, specificity, and stability will enrich the research of nanozymes and pave new ways in designing multifunctional nanozymes.
- 14Zhang, R.; Fan, K.; Yan, X. Nanozymes: created by learning from nature. Sci. China Life Sci. 2020, 63 (8), 1183– 1200, DOI: 10.1007/s11427-019-1570-7Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB38%252FjvVajsA%253D%253D&md5=4d094c61c72ed1da761ceae728519535Nanozymes: created by learning from natureZhang Ruofei; Fan Kelong; Yan Xiyun; Fan Kelong; Yan XiyunScience China. Life sciences (2020), 63 (8), 1183-1200 ISSN:.Nanozymes, a type of nanomaterials with enzyme-like activity, have shown great potential to replace natural enzymes in many fields such as biochemical detection, environmental management and disease treatment. However, the catalytic efficiency and substrate specificity of nanozymes still need improvement. To further optimize the enzymatic properties of nanozymes, recent studies have introduced the structural characteristics of natural enzymes into the rational design of nanozymes, either by employing small molecules to mimic the cofactors of natural enzymes to boost nanozymes' catalytic potential, or by simulating the active center of natural enzymes to construct the nanostructure of nanozymes. This review introduces the commonly used bio-inspired strategies to create nanozymes, aiming at clarifying the current progress and bottlenecks. Advances and challenges focusing on the research of bio-inspired nanozymes are outlined to provide ideas for the de novo design of ideal nanozymes.
- 15Golchin, K.; Golchin, J.; Ghaderi, S.; Alidadiani, N.; Eslamkhah, S.; Eslamkhah, M.; Davaran, S.; Akbarzadeh, A. Gold nanoparticles applications: from artificial enzyme till drug delivery. Artif. Cells Nanomed. Biotechnol. 2018, 46 (2), 250– 254, DOI: 10.1080/21691401.2017.1305393Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXnvVCrurw%253D&md5=9f31de7f4da4a8da58c1e9951f09c299Gold nanoparticles applications: from artificial enzyme till drug deliveryGolchin, Kazem; Golchin, Jafar; Ghaderi, Shahrooz; Alidadiani, Neda; Eslamkhah, Sajjad; Eslamkhah, Masoud; Davaran, Soodabeh; Akbarzadeh, AbolfazlArtificial Cells, Nanomedicine, and Biotechnology (2018), 46 (2), 250-254CODEN: ACNBCI; ISSN:2169-141X. (Taylor & Francis Ltd.)A review. Today, nano-medicine promotes new therapeutics and diagnostics tools, including sensing of biomols. as a biosensor, cancer chemotherapy and drug or gene delivery. Because of small size and biocompatibility of gold nanoparticles (GNPs), they become a good candidate for biol. application. Also, thanks to their biol. and chem. properties, they can mimic function of some enzymes including super oxide dismutase (SOD), esterase, etc. Also, biomaterials and bioengineering have grown so fast since the last decade for many therapeutic applications such as tissue regeneration. Among these cutting edge technol., nanomaterials find the way to becoming a very powerful tool for using in many fields of researchers including biosensing, gene therapy and chemotherapy. In this review, we focused on some biol. applications of GNPs in biol. and medicine.
- 16Wang, X.; Mei, Z.; Wang, Y.; Tang, L. Comparison of four methods for the biofunctionalization of gold nanorods by the introduction of sulfhydryl groups to antibodies. Beilstein J. Nanotechnol. 2017, 8 (1), 372– 380, DOI: 10.3762/bjnano.8.39Google Scholar16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXpslejsLk%253D&md5=7502733f116e9df264b6ab7a8c3910a1Comparison of four methods for the biofunctionalization of gold nanorods by the introduction of sulfhydryl groups to antibodiesWang, Xuefeng; Mei, Zhong; Wang, Yanyan; Tang, LiangBeilstein Journal of Nanotechnology (2017), 8 (), 372-380CODEN: BJNEAH; ISSN:2190-4286. (Beilstein-Institut zur Foerderung der Chemischen Wissenschaften)Introducing sulfhydryl groups to biomols. to functionalize gold nanorods (GNRs) is an attractive method that involves the creation of a strong Au-S bond. Previously, we developed a facile method to functionalize GNR surfaces by thiolating antibodies using Traut's reagent. In the current study, we evaluated several methods for the introduction of thiol groups onto the surface of GNRs by using Traut's reagent, dithiotreitol (DTT), dithiolarom. PEG6-CONHNH , and thiol-polyethylene glycolamine (SHPEG-NH) combined with EDC reaction. We showed that the four above-mentioned thiolation methods can efficiently functionalize GNRs and simplify the functionalization procedures. The formed GNR-bioconjugates showed superior stability without compromising the biol. activity. The GNR nanochip prepd. with these four thiolated antibodies can detect human IgG targets with specificity. However, SH-PEG-NH combined with EDC reaction may affect the amt. of functionalized GNRs because of the efficiency of thiol moiety linkage to antibodies, thereby affecting the sensitivity of the GNR sensor. The introduction of a thiol group to antibodies by using Traut's reagent, DTT, and PEG6-CONHNH allowed for direct immobilization onto the GNR surface, improved the efficacy of functionalized GNRs, and increased the sensitivity in response to target detection as a biosensor. Given that PEG6-CONHNH modification requires glycosylated biomols., Traut's reagent and DTT thiolation are recommended as universal applications of GNR biofunctionalization and can be easily extended to other sensing applications based on other gold nanostructures or new biomols.
- 17Chang, J.-Y.; Wu, H.; Chen, H.; Ling, Y.-C.; Tan, W. Oriented assembly of Au nanorods using biorecognition system. Chem. Commun. 2005, (8), 1092– 1094, DOI: 10.1039/b414059aGoogle Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhsFOktbk%253D&md5=0eca59aa6fb2af851768008fa0f669e2Oriented assembly of Au nanorods using biorecognition systemChang, Jia-Yaw; Wu, Huimeng; Chen, Hui; Ling, Yong-Chien; Tan, WeihongChemical Communications (Cambridge, United Kingdom) (2005), (8), 1092-1094CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)The design and formation of a linear assembly of gold nanorods using a biomol. recognition system are described. Anti-mouse IgG was immobilized on the {111} end faces of gold nanorods through a thioctic acid contg. a terminal carboxyl group. The biofunctionalized nanorods can be assembled with the desired length using mouse IgG for biorecognition and binding. The gold nanorods can be assembled to extended nanorod chains, which can be as long as 3 μm. These assembled nanostructures may be used as the precursors for future nanodevices.
- 18Turkevich, J.; Stevenson, P. C.; Hillier, J. A study of the nucleation and growth processes in the synthesis of colloidal gold. Discuss. Faraday Soc. 1951, 11, 55– 75, DOI: 10.1039/df9511100055Google ScholarThere is no corresponding record for this reference.
- 19BarathManiKanth, S.; Kalishwaralal, K.; Sriram, M.; Pandian, S. R. K.; Youn, H.-s.; Eom, S.; Gurunathan, S. Anti-oxidant effect of gold nanoparticles restrains hyperglycemic conditions in diabetic mice. J. Nanobiotechnol. 2010, 8 (1), 16, DOI: 10.1186/1477-3155-8-16Google Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC3cjit1yrug%253D%253D&md5=44597ea21df720db7092b7bc7c8797b2Anti-oxidant effect of gold nanoparticles restrains hyperglycemic conditions in diabetic miceBarathmanikanth Selvaraj; Kalishwaralal Kalimuthu; Sriram Muthuirulappan; Pandian Sureshbabu Ram Kumar; Youn Hyung-Seop; Eom Soohyun; Gurunathan SangiliyandiJournal of nanobiotechnology (2010), 8 (), 16 ISSN:.BACKGROUND: Oxidative stress is imperative for its morbidity towards diabetic complications, where abnormal metabolic milieu as a result of hyperglycemia, leads to the onset of several complications. A biological antioxidant capable of inhibiting oxidative stress mediated diabetic progressions; during hyperglycemia is still the need of the era. The current study was performed to study the effect of biologically synthesized gold nanoparticles (AuNPs) to control the hyperglycemic conditions in streptozotocin induced diabetic mice. RESULTS: The profound control of AuNPs over the anti oxidant enzymes such as GSH, SOD, Catalase and GPx in diabetic mice to normal, by inhibition of lipid peroxidation and ROS generation during hyperglycemia evidence their anti-oxidant effect during hyperglycemia. The AuNPs exhibited an insistent control over the blood glucose level, lipids and serum biochemical profiles in diabetic mice near to the control mice provokes their effective role in controlling and increasing the organ functions for better utilization of blood glucose. Histopathological and hematological studies revealed the non-toxic and protective effect of the gold nanoparticles over the vital organs when administered at dosage of 2.5 mg/kilogram.body.weight/day. ICP-MS analysis revealed the biodistribution of gold nanoparticles in the vital organs showing accumulation of AuNPs in the spleen comparatively greater than other organs. CONCLUSION: The results obtained disclose the effectual role of AuNPs as an anti-oxidative agent, by inhibiting the formation of ROS, scavenging free radicals; thus increasing the anti-oxidant defense enzymes and creating a sustained control over hyperglycemic conditions which consequently evoke the potential of AuNPs as an economic therapeutic remedy in diabetic treatments and its complications.
- 20He, S.; Chua, J.; Tan, E. K. M.; Kah, J. C. Y. Optimizing the SERS enhancement of a facile gold nanostar immobilized paper-based SERS substrate. RSC Adv. 2017, 7 (27), 16264– 16272, DOI: 10.1039/C6RA28450GGoogle Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXktFyrtr8%253D&md5=b7e82415da36f996c721d2dfa5f07d56Optimizing the SERS enhancement of a facile gold nanostar immobilized paper-based SERS substrateHe, Shuai; Chua, Jefri; Tan, Eddie Khay Ming; Kah, James Chen YongRSC Advances (2017), 7 (27), 16264-16272CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)While surface-enhanced Raman scattering (SERS) is a useful technique for the rapid and sensitive detection of biochem. compds., conventional SERS chips suffer from high cost, complicated fabrication, inefficient sample collection processes and being not biocompatible. Here, we developed a facile, low-cost and highly sensitive gold nanostar (AuNS) immobilized paper-based SERS substrate that can be easily prepd. in any lab. We performed studies on the paper materials, immobilization strategies, and SERS acquisition conditions to optimize the SERS enhancement and demonstrated that an optimized SERS signal was obtained from a dry substrate and wet analyte configuration suitable for rapid point-of-care detection. Using crystal violet (CV) as the Raman probe mol., the optimized SERS substrate was prepd. by having multiple drops of ∼100 pM of sodium citrate-treated colloidal AuNS on common lab. filter paper before acquiring SERS spectra of CV freshly dripped onto the pre-dried AuNS-filter paper substrate. The optimized AuNS-filter paper substrate exhibited a SERS enhancement factor higher than that of two com. Au/Ag-based SERS chips, with a detection limit of 1 nM CV and a SERS enhancement factor of up to 1.2 × 107. Such an optimized dry substrate and wet analyte configuration meant that the paper-based SERS substrate could be stored before use and Raman acquisition could be performed immediately without the need for the sample to dry. This makes the AuNS-filter paper substrate a simple and low-cost tool for trace level detection of biochem. species in a rapid, sensitive and non-destructive manner.
- 21Ivanov, M. R.; Bednar, H. R.; Haes, A. J. Investigations of the mechanism of gold nanoparticle stability and surface functionalization in capillary electrophoresis. ACS Nano 2009, 3 (2), 386– 394, DOI: 10.1021/nn8005619Google Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXmtFGqtw%253D%253D&md5=a9d97ee5bfcadb378982d41ddb6b0f58Investigations of the Mechanism of Gold Nanoparticle Stability and Surface Functionalization in Capillary ElectrophoresisIvanov, Michael R.; Bednar, Heidi R.; Haes, Amanda J.ACS Nano (2009), 3 (2), 386-394CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Covalently functionalized gold nanoparticles influence capillary electrophoresis sepns. of neurotransmitters in a concn.- and surface-chem.-dependent manner. Gold nanoparticles with either primarily covalently functionalized carboxylic acid (Au@COOH) or amine (Au@NH2) surface groups are characterized using extinction spectroscopy, transmission electron microscopy, and zeta potential measurements. The impact of the presence of nanoparticles and their surface chem. is investigated, and at least three nanoparticle-specific mechanisms are found to effect sepns. First, the degree of nanoparticle-nanoparticle interactions is quantified using a new parameter termed the crit. nanoparticle concn. (CNC). CNC is defined as the lowest concn. of nanoparticles that induces predominant nanoparticle aggregation under specific buffer conditions and is detd. using dual-wavelength photodiode array detection. Once the CNC has been exceeded, reproducible sepns. are no longer obsd. Second, nanoparticle-analyte interactions are dictated by electrostatic interactions which depend on the pKa of the analyte and surface charge of the nanoparticle. Finally, nanoparticle-capillary interactions occur in a surface-chem.-dependent manner. Run buffer viscosity is influenced by the formation of a nanoparticle steady-state pseudostationary phase along the capillary wall. Despite differences in buffer viscosity leading to changes in neurotransmitter mobilities, no significant changes in electroosmotic flow were obsd. As a result of these three nanoparticle-specific interactions, Au@NH2 nanoparticles increase the mobility of the neurotransmitters while a smaller opposite effect is obsd. for Au@COOH nanoparticles. Understanding nanoparticle behavior in the presence of an elec. field will have significant impacts in sepn. science where nanoparticles can serve to improve either the mobility or detection sensitivity of target mols.
- 22Liu, W.; Tian, L.; Du, J.; Wu, J.; Liu, Y.; Wu, G.; Lu, X. Triggered peroxidase-like activity of Au decorated carbon dots for colorimetric monitoring of Hg2+ enrichment in Chlorella vulgaris. Analyst 2020, 145 (16), 5500– 5507, DOI: 10.1039/D0AN00930JGoogle Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtFCnu7bK&md5=f49b4f4075704f009c1b95f64033798cTriggered peroxidase-like activity of Au decorated carbon dots for colorimetric monitoring of Hg2+ enrichment in Chlorella vulgarisLiu, Wene; Tian, Lili; Du, Jie; Wu, Jiangmin; Liu, Yongmei; Wu, Guofan; Lu, XiaoquanAnalyst (Cambridge, United Kingdom) (2020), 145 (16), 5500-5507CODEN: ANALAO; ISSN:0003-2654. (Royal Society of Chemistry)Developing a rapid, low-cost, and multimode detection method for heavy metal ions remains a compelling goal for many applications, including food safety, environmental and biol. anal. This study investigated the influence of Hg2+ on the peroxidase-like activity of gold nanoparticles (GNPs) decorated on carbon dots (CDs) from lysine (denoted as GNP@CDs). A new type of Hg2+-triggered peroxidase-like activity of GNP@CDs was discovered, which could catalyze the oxidn. of the colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue TMB. Based on the regulation of the catalytically triggered activity, a sensitive colorimetric method for the detection of Hg2+ was developed, with a linear range of 7-150 nM, providing a limit of detection as low as 3.7 nM. The sensor is simple and rapid, and was successfully applied to the detection of Hg2+ enrichment in chlorella, suggesting a promising application in biol. anal.
- 23Ko, E.; Tran, V.-K.; Son, S. E.; Hur, W.; Choi, H.; Seong, G. H. Characterization of Au@PtNP/GO nanozyme and its application to electrochemical microfluidic devices for quantification of hydrogen peroxide. Sens. Actuators, B 2019, 294, 166– 176, DOI: 10.1016/j.snb.2019.05.051Google Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtVekur3F&md5=83f0347982a4875e7b3b30cd334ba6b3Characterization of Au@PtNP/GO nanozyme and its application to electrochemical microfluidic devices for quantification of hydrogen peroxideKo, Euna; Tran, Van-Khue; Son, Seong Eun; Hur, Won; Choi, Hyun; Seong, Gi HunSensors and Actuators, B: Chemical (2019), 294 (), 166-176CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Nanostructured artificial enzymes, known as nanozymes, have been considered effective alternatives for natural enzymes with the attractive advantages. Herein, bimetallic Au and Pt nanoparticles with graphene oxide (GO) were immobilized chem. on the surface of agarose microbeads. Due to the synergistic effect of the bimetallic nanoparticles and GO (Au@PtNP/GO), this hybrid nanostructure exhibited strong peroxidase-like catalytic activity toward 3,3',5,5'-tetramethylbenzidine (TMB) substrate in the presence of H2O2. Colorimetric detn. of H2O2, indicated by the blue color of the oxidized TMB within 1 min, was obsd. using the Au@PtNP/GO nanozymes. To demonstrate practical application of the nanozymes, the Au@PtNP/GO microbeads were packed into a film-based electrochem. point-of-care (POC) device for sensitive and rapid H2O2 detection. Upon introduction of TMB substrate soln. contg. H2O2, the catalytically oxidized TMB was electrochem. reduced on the electrode surfaces, resulting in a broader detection range of H2O2 (1 μM - 3 mM) and a lower LOD (1.62 μM) than achievable with the colorimetric detection method. Moreover, the developed POC devices showed the capability of accurate detn. of H2O2 with strong repeatability and reproducibility in real sample test using artificial urine.
- 24Poulos, T. L. Heme enzyme structure and function. Chem. Rev. 2014, 114 (7), 3919– 3962, DOI: 10.1021/cr400415kGoogle Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXkvFGgsg%253D%253D&md5=e7857cca01883857d47254628ed69918Heme Enzyme Structure and FunctionPoulos, Thomas L.Chemical Reviews (Washington, DC, United States) (2014), 114 (7), 3919-3962CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Metalloporphyrins are employed in various capacities throughout the biosphere, and of these, heme (iron protoporphyrin IX) is one of the most abundant and widely used. Heme is well-known for its roles in shuttling electrons between proteins as seen in mitochondrial respiration and in O2 storage as is the case with globins, but it also serves as a cofactor in multiple enzyme-mediated processes. Although heme enzymes can catalyze both reductive and oxidative reactions, the present review focuses primarily on those that catalyze oxidn. reactions, and esp. those for which crystal structures are available.
- 25Guéant, J.-L.; Caillerez-Fofou, M.; Battaglia-Hsu, S.; Alberto, J.-M.; Freund, J.-N.; Dulluc, I.; Adjalla, C.; Maury, F.; Merle, C.; Nicolas, J.-P. Molecular and cellular effects of vitamin B12 in brain, myocardium and liver through its role as co-factor of methionine synthase. Biochimie 2013, 95 (5), 1033– 1040, DOI: 10.1016/j.biochi.2013.01.020Google Scholar25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjt1Wqtr4%253D&md5=8ba214c24735ae3a9d22cc05ddc586b9Molecular and cellular effects of vitamin B12 in brain, myocardium and liver through its role as co-factor of methionine synthaseGueant, Jean-Louis; Caillerez-Fofou, Maatem; Battaglia-Hsu, Shyuefang; Alberto, Jean-Marc; Freund, Jean-Noel; Dulluc, Isabelle; Adjalla, Charles; Maury, Florence; Merle, Carole; Nicolas, Jean-Pierre; Namour, Fares; Daval, Jean-LucBiochimie (2013), 95 (5), 1033-1040CODEN: BICMBE; ISSN:0300-9084. (Elsevier Masson SAS)A review. Vitamin B12 (cobalamin, cbl) is a cofactor of methionine synthase (MTR) in the synthesis of methionine, the precursor of the universal Me donor S-Adenosylmethionine (SAM), which is involved in epigenomic regulatory mechanisms. We have established a neuronal cell model with stable expression of a transcobalamin-oleosin chimer and subsequent decreased cellular availability of vitamin B12, which produces reduced proliferation, increased apoptosis and accelerated differentiation through PP2A, NGF and TACE pathways. Anti-transcobalamin antibody or impaired transcobalamin receptor expression produce also impaired proliferation in other cells. Consistently, the transcription, protein expression and activity of MTR are increased in proliferating cells of skin and intestinal epitheliums, in rat intestine crypts and in proliferating CaCo2 cells, while MTR activity correlates with DNA methylation in rat intestine villi. Exposure to nitrous oxide in animal models identified impairment of MTR reaction as the most important metabolic cause of neurol. manifestations of B12 deficiency. Early vitamin B12 and folate deprivation during gestation and lactation of a dam-progeny' rat model developed in our lab. is assocd. with long-lasting disabilities of behavior and memory capacities, with persisting hallmarks related to increased apoptosis, impaired neurogenesis and altered plasticity. We found also an epigenomic deregulation of energy metab. and fatty acids beta-oxidn. in myocardium and liver, through imbalanced methylation/acetylation of PGC-1α and decreased expression of SIRT1. These nutrigenomic effects display similarities with the mol. mechanisms of fetal programming. Beside deficiency, B12 loading increases the expression of MTR through internal ribosome entry sites (IRES) and down-regulates MDR-1 gene expression. In conclusion, vitamin B12 influences cell proliferation, differentiation and apoptosis in brain. Vitamin B12 and folate combined deficiency impairs fatty acid oxidn. and energy metab. in liver and heart through epigenomic mechanisms related to imbalanced acetylation/methylation. Some but not all of these effects reflect the upstream role of vitamin B12 in SAM synthesis.
- 26Okamoto, K.; Kusano, T.; Nishino, T. Chemical nature and reaction mechanisms of the molybdenum cofactor of xanthine oxidoreductase. Curr. Pharm. Des. 2013, 19 (14), 2606– 2614, DOI: 10.2174/1381612811319140010Google Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXmt1ygtbg%253D&md5=a75046d0a1c789b4cad99beeffa00c9aChemical nature and reaction mechanisms of the molybdenum cofactor of xanthine oxidoreductaseOkamoto, Ken; Kusano, Teruo; Nishino, TakeshiCurrent Pharmaceutical Design (2013), 19 (14), 2606-2614CODEN: CPDEFP; ISSN:1381-6128. (Bentham Science Publishers Ltd.)A review. Xanthine oxidoreductase (XOR), a complex flavoprotein, catalyzes the metabolic reactions leading from hypoxanthine to xanthine and from xanthine to urate, and both reactions take place at the molybdenum cofactor. The enzyme is a target of drugs for therapy of gout or hyperuricemia. We review the chem. nature and reaction mechanisms of the molybdenum cofactor of XOR, focusing on molybdenum-dependent reactions of actual or potential medical importance, including nitric oxide (NO) synthesis. It is now generally accepted that XOR transfers the water-exchangeable -OH ligand of the molybdenum atom to the substrate. The hydroxyl group at OH- Mo(IV) can be replaced by urate, oxipurinol and FYX-051 derivs. and the structures of these complexes have been detd. by x-ray crystallog. under anaerobic conditions. Although formation of NO from nitrite or formation of xanthine from urate by XOR is chem. feasible, it is not yet clear whether these reactions have any physiol. significance since the reactions are catalyzed at a slow rate even under anaerobic conditions.
- 27Kumeria, T.; McInnes, S. J.; Maher, S.; Santos, A. Porous silicon for drug delivery applications and theranostics: recent advances, critical review and perspectives. Expert Opin. Drug Delivery 2017, 14 (12), 1407– 1422, DOI: 10.1080/17425247.2017.1317245Google Scholar27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXmtlOgsr4%253D&md5=4d83c217147c34afeb032bec5feb5f87Porous silicon for drug delivery applications and theranostics: recent advances, critical review and perspectivesKumeria, Tushar; McInnes, Steven J. P.; Maher, Shaheer; Santos, AbelExpert Opinion on Drug Delivery (2017), 14 (12), 1407-1422CODEN: EODDAW; ISSN:1742-5247. (Taylor & Francis Ltd.)A review. Porous silicon (pSi) engineered by electrochem. etching has been used as a drug delivery vehicle to address the intrinsic limitations of traditional therapeutics. Biodegradability, biocompatibility, and optoelectronic properties make pSi a unique candidate for developing biomaterials for theranostics and photodynamic therapies. This review presents an updated overview about the recent therapeutic systems based on pSi, with a crit. anal. on the problems and opportunities that this technol. faces as well as highlighting pSis growing potential. Recent progress in pSi-based research includes drug delivery systems, including biocompatibility studies, drug delivery, theranostics, and clin. trials with the most relevant examples of pSi-based systems presented here. A crit. anal. about the tech. advantages and disadvantages of these systems is provided along with an assessment on the challenges that this technol. faces, including clin. trials and investors support. PSi is an outstanding material that could improve existing drug delivery and photodynamic therapies in different areas, paving the way for developing advanced theranostic nanomedicines and incorporating payloads of therapeutics with imaging capabilities. However, more extensive in-vivo studies are needed to assess the feasibility and reliability of this technol. for clin. practice. The tech. and com. challenges that this technol. face are still uncertain.
- 28Kumeria, T.; Wang, J.; Chan, N.; Harris, T. J.; Sailor, M. J. Visual sensor for sterilization of polymer fixtures using embedded mesoporous silicon photonic crystals. ACS Sens. 2018, 3 (1), 143– 150, DOI: 10.1021/acssensors.7b00764Google Scholar28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXitVSitbjF&md5=abeb38659b445c6c6b48718ae4eaf8a3Visual Sensor for Sterilization of Polymer Fixtures Using Embedded Mesoporous Silicon Photonic CrystalsKumeria, Tushar; Wang, Joanna; Chan, Nicole; Harris, Todd J.; Sailor, Michael J.ACS Sensors (2018), 3 (1), 143-150CODEN: ASCEFJ; ISSN:2379-3694. (American Chemical Society)A porous photonic crystal is integrated with a plastic medical fixture (IV connector hub) to provide a visual colorimetric sensor to indicate the presence or absence of alc. used to sterilize the fixture. The photonic crystal is prepd. in porous silicon (pSi) by electrochem. anodization of single crystal silicon, and the porosity and the stop band of the material is engineered such that the integrated device visibly changes color (green to red or blue to green) when infiltrated with alc. Two types of self-reporting devices are prepd. and their performance compared: the first type involves heat-assisted fusion of a freestanding pSi photonic crystal to the connector end of a preformed polycarbonate hub, forming a composite where the unfilled portion of the pSi film acts as the sensor; the second involves generation of an all-polymer replica of the pSi photonic crystal by complete thermal infiltration of the pSi film and subsequent chem. dissoln. of the pSi portion. Both types of sensors visibly change color when wetted with alc., and the color reverts to the original upon evapn. of the liq. The sensor performance is verified using E. coli-infected samples.
- 29Harraz, F. A.; Tsuboi, T.; Sasano, J.; Sakka, T.; Ogata, Y. Metal deposition onto a porous silicon layer by immersion plating from aqueous and nonaqueous solutions. J. Electrochem. Soc. 2002, 149 (9), C456, DOI: 10.1149/1.1498841Google Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XmtVCmu74%253D&md5=d06b9d05c475884ea6c7009c4edaaf21Metal Deposition onto a Porous Silicon Layer by Immersion Plating from Aqueous and Nonaqueous SolutionsHarraz, F. A.; Tsuboi, T.; Sasano, J.; Sakka, T.; Ogata, Y. H.Journal of the Electrochemical Society (2002), 149 (9), C456-C463CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)Immersion plating of metals (Ag, Cu, Ni) onto a porous Si (PS) layer from aq. and nonaq. solns. was studied. The modified PS layers after the immersion plating were analyzed by x-ray diffraction and XPS. FTIR spectroscopy and SEM were also performed to study the structural changes and microstructure of PS samples after the plating process. In both solns., the deposition of metal oxidizes PS simultaneously to SiO2. The different deposition behaviors are discussed in terms of different rest potentials of PS in these solns. and electrode potential of each metal. Immersion plating in nonaq. org. solns. shows that a trace of residual H2O affects the metal deposition. Based on the results obtained, the mechanism of metal deposition is proposed. The metal deposition proceeds by nucleation and growth via the local cell mechanism. Also metal deposition proceeds very differently on Si wafer and PS surfaces. The different deposition behaviors on both surfaces are discussed.
- 30Andsager, D.; Hilliard, J.; Nayfeh, M. Behavior of porous silicon emission spectra during quenching by immersion in metal ion solutions. Appl. Phys. Lett. 1994, 64 (9), 1141– 1143, DOI: 10.1063/1.110832Google Scholar30https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXivVenur8%253D&md5=61cd0c2a0df6c6bf6bbd34917f1133afBehavior of porous silicon emission spectra during quenching by immersion in metal ion solutionsAndsager, D.; Hilliard, J.; Nayfeh, M. H.Applied Physics Letters (1994), 64 (9), 1141-3CODEN: APPLAB; ISSN:0003-6951.The luminescence emission of porous Si was regularly measured while immersed in dil. metal ion solns. of Cu, Ag, and Au. The emission spectra show progressive quenching that advances from the blue edge towards the red edge of the emission band, causing a continuous shift in the band center and a narrowing of its width. Auger electron spectroscopy data show that the penetration of the metal adsorbate into the porous layer correlates with the degree of quenching of the luminescence. These results are interpreted as a progression of the quenching of the luminescence inward from the surface of the simple toward the bulk.
- 31Harraz, F. A.; Ismail, A. A.; Bouzid, H.; Al-Sayari, S.; Al-Hajry, A.; Al-Assiri, M. Surface-enhanced Raman scattering (SERS)-active substrates from silver plated-porous silicon for detection of crystal violet. Appl. Surf. Sci. 2015, 331, 241– 247, DOI: 10.1016/j.apsusc.2015.01.042Google Scholar31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXht1Ogtbs%253D&md5=b126ed65204c882e1273d4c8dbdd5109Surface-enhanced Raman scattering (SERS)-active substrates from silver plated-porous silicon for detection of crystal violetHarraz, Farid A.; Ismail, Adel A.; Bouzid, Houcine; Al-Sayari, S. A.; Al-Hajry, A.; Al-Assiri, M. S.Applied Surface Science (2015), 331 (), 241-247CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Silver nanoparticles (AgNPs) have been reduced onto porous silicon (PSi) surface in a simple immersion plating bath. Here, PSi with av. pore size of ∼30 nm was used as both a mech. support and a mild reducing agent. AgNPs-meso-PSi hybrid structures exhibit a highly sensitive and reproducible surface-enhanced Raman scattering (SERS) response. A detectable concn. as low as 100 pM of crystal violet has been achieved with an enhancement factor (EF) of 1.3 × 106. No aging effect was obsd. for the current substrates after storing in air for three weeks. The large EF is essentially attributed to a combination of electromagnetic enhancement and charge transfer mechanism.
- 32Andsager, D.; Hilliard, J.; Hetrick, J.; AbuHassan, L.; Plisch, M.; Nayfeh, M. Quenching of porous silicon photoluminescence by deposition of metal adsorbates. J. Appl. Phys. 1993, 74 (7), 4783– 4785, DOI: 10.1063/1.354350Google Scholar32https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXktVyktw%253D%253D&md5=e33d454c967b6c39d2429c852589541dQuenching of porous silicon photoluminescence by deposition of metal adsorbatesAndsager, D.; Hillard, J.; Hetrick, J. M.; AbuHassan, L. H.; Plisch, M.; Nayfeh, M. H.Journal of Applied Physics (1993), 74 (7), 4783-5CODEN: JAPIAU; ISSN:0021-8979.Various metals were deposited on luminescent porous silicon (PS) by immersion in metal ion solns. and by evapn. The photoluminescence (PL) was quenched upon immersion in ionic solns. of Cu, Ag, and Au but not noticeably quenched in other ionic solns. Evapn. of 100 Å of Cu or 110 Å of Au was not obsd. to quench PL. Auger electron spectroscopy performed on samples quenched and then immediately removed from soln. showed a metallic concn. in the PS layer of order 10 at.%, but persisting to a depth of order 3000 Å.
- 33Al-Syadi, A.; Faisal, M.; El-Toni, A. M.; Khan, A.; Jalalah, M.; Alsareii, S.; Harraz, F. A. Surface-enhanced Raman scattering (SERS) active substrate from gold nanoparticle-coated porous silicon for sensitive detection of horseradish peroxidase enzyme. Mater. Chem. Phys. 2022, 281, 125931 DOI: 10.1016/j.matchemphys.2022.125931Google Scholar33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XmtFOhtLw%253D&md5=587272e58e7a7c53cd28fe934b6c1c03Surface-enhanced Raman scattering (SERS) active substrate from gold nanoparticle-coated porous silicon for sensitive detection of horseradish peroxidase enzymeAl-Syadi, A. M.; Faisal, M.; El-Toni, Ahmed Mohamed; Khan, Aslam; Jalalah, Mohammed; Alsareii, S. A.; Harraz, Farid A.Materials Chemistry and Physics (2022), 281 (), 125931CODEN: MCHPDR; ISSN:0254-0584. (Elsevier B.V.)The sensitive detection of horseradish peroxidase (HRP) enzyme using a gold nanoparticle/porous silicon (AuNPs/PSi) active substrate via surface-enhanced Raman scattering (SERS) is demonstrated. Electrochem. porosification via galvanostatic anodization in hydrofluoric acid (HF) mixed with ethanol was used to fabricate mesopore-size PSi layers onto a p-type Si (100) wafer. The AuNPs were reduced onto the meso-PSi surface through a spontaneous galvanic displacement reaction by dipping the substrates in a simple plating bath. The structural features and morphol. of the designed frameworks were elucidated by X-ray diffraction (XRD) anal., field-emission SEM (FESEM), energy-dispersive X-ray spectroscopy (EDX), and XPS. The SERS performance of the AuNPs/PSi substrate was firstly examd. and evaluated using crystal violet dye as the target analyte, where it exhibited enhanced SERS response. Moreover, the active substrate displayed an extremely sensitive and reproducible SERS response toward the HRP enzyme as a reactive analyte. The active substrate exhibited excellent detectable performance with a very low concn. of 10-8 M HRP and an enhancement factor (EF) of approx. 4.8 x 105. The anal. enhancement of Raman signals in response to Au plasmonic nanoparticles signifies the combination of the charge-transfer mechanism and electromagnetic amplification because of the formed d. of hotspot regions. Therefore, the current newly fabricated AuNPs/PSi substrates have optimistic prospects in biophys., biochem., and biomedical applications as highly active SERS substrates.
- 34Coulthard, I.; Jiang, D.; Lorimer, J.; Sham, T.; Feng, X. Reductive deposition of palladium on porous silicon from aqueous solutions of palladium dichloride: an X-ray absorption fine structure study. Langmuir 1993, 9 (12), 3441– 3445, DOI: 10.1021/la00036a018Google Scholar34https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXmsl2ksLw%253D&md5=d93b2d17e918532242307a697b9f8846Reductive deposition of palladium on porous silicon from aqueous solutions of palladium dichloride: an x-ray absorption fine structure studyCoulthard, I.; Jiang, D. T.; Lorimer, J. W.; Sham, T. K.; Feng, X. H.Langmuir (1993), 9 (12), 3441-5CODEN: LANGD5; ISSN:0743-7463.A method for the deposition of Pd on the vast surface of porous Si from aq. solns. of PdCl2 is described. The deposited Pd and the porous Si substrate were characterized by using x-ray absorption fine structure (XAFS) spectroscopy. Deposition can be carried out in a controlled manner, that the deposited Pd is metallic, and that the oxidn.-redn. reaction responsible for the reductive deposition of Pd from PdCl2(aq) takes place at sp. surface sites.
- 35Al-Syadi, A. M.; Faisal, M.; Harraz, F. A.; Jalalah, M.; Alsaiari, M. Immersion-plated palladium nanoparticles onto meso-porous silicon layer as novel SERS substrate for sensitive detection of imidacloprid pesticide. Sci. Rep. 2021, 11 (1), 9174 DOI: 10.1038/s41598-021-88326-0Google Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhtVSrurrE&md5=f90730d271c8d48fcce381f204bed74fImmersion-plated palladium nanoparticles onto meso-porous silicon layer as novel SERS substrate for sensitive detection of imidacloprid pesticideAl-Syadi, A. M.; Faisal, M.; Harraz, Farid A.; Jalalah, Mohammed; Alsaiari, MabkhootScientific Reports (2021), 11 (1), 9174CODEN: SRCEC3; ISSN:2045-2322. (Nature Research)Herein, we demonstrate the effectiveness of surface-enhanced Raman scattering (SERS) to detect trace concn. of potentially harmful imidacloprid pesticide. To achieve this ultimate objective, a rapid and highly effective methodol. for the fabrication of active and stable porous silicon (PSi) plated palladium nanoparticles (PdNPs) SERS substrates by an electrochem. anodization and immersion plating routes was applied. The PSi layers were fabricated by the electrochem. anodization of a silicon wafer in ethanoic fluoride soln., followed by uniformly deposition of PdNPs via a simple immersion plating technique. The structural features and morphol. of fabricated frameworks of PSi-Pd NPs have been investigated by field emission SEM (FE-SEM) with energy dispersive X-ray (EDX), X-ray diffraction (XRD), XPS and Fourier transform IR (FT-IR) spectra. The SERS signal of imidacloprid using PSi-Pd NPs substrate exhibited immense enhancement compared to the Si-Pd NPs substrate. This large EF is fundamentally ascribed to the combined effect of the electromagnetic improvement and charge transfer mechanisms. Addnl., no aging effect was obsd. for the present substrates kept in air for two weeks. Striking enhancement in Raman spectral signals obtained with the current PSi-Pd NPs substrates can provide a simple and smooth platform towards the sensitive detection of various target analytes.
- 36Jabbar, A. A.; Alwan, A. M. Efficient detecting of TNT molecules using palladium nanoparticles/cross shape pores like structure porous silicon. Vib. Spectrosc. 2019, 103, 102933 DOI: 10.1016/j.vibspec.2019.102933Google Scholar36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXht1aqtL3O&md5=7a0e386a6388a089153cf1d67f1080f4Efficient detecting of TNT molecules using palladium nanoparticles/ cross shape pores like structure porous siliconJabbar, Allaa A.; Alwan, Alwan M.Vibrational Spectroscopy (2019), 103 (), 102933CODEN: VISPEK; ISSN:0924-2031. (Elsevier B.V.)A set of porous silicon PSi samples with different cross-shaped pores like structures are successfully synthesized by using double successive wet anisotropic etching process: KOH wet chem. process and laser-assisted etching (LAE) process. Four different forms of palladium nanoparticles are deposited on PSi substrate to fabricate PdNPs/PSi heterostructures. Surface-enhanced Raman scattering (SERS)-active PdNPs/PSi heterostructures are fabricated and investigated for detecting Trinitrotoluene (TNT) mols. Dipping plating process of PSi in 0.05 M concn. of PdCl2 soln. at room temp. for 15 min is used to assemble spread of surface morphologies PdNPs layer over PSi. The results show that the SERS of heterostructures for TNT mols. expos strong reliance on the d. of hot-spot junctions more than the local surface plasmonic of PdNPs. Anal. Enhancement factor (EF) of the Raman signal is varied according to the formed d. of hot spots regions.
- 37Ensafi, A. A.; Abarghoui, M. M.; Rezaei, B. Simultaneous determination of morphine and codeine using Pt nanoparticles supported on porous silicon flour modified ionic liquid carbon paste electrode. Sens. Actuators, B 2015, 219, 1– 9, DOI: 10.1016/j.snb.2015.05.010Google Scholar37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXos1OksLY%253D&md5=228216f1898e1041eaa766fa11518a0fSimultaneous determination of morphine and codeine using Pt nanoparticles supported on porous silicon flour modified ionic liquid carbon paste electrodeEnsafi, Ali A.; Abarghoui, Mehdi Mokhtari; Rezaei, BehzadSensors and Actuators, B: Chemical (2015), 219 (), 1-9CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Pt nanoparticles supported on porous silicon (PSi) flour was synthesized by a simple in-situ redox reaction between PtCl2-6 and PSi, in hydrofluoric acid soln. The components and morphol. properties of Pt/PSi nanocomposites were investigated by means of SEM, X-ray diffraction spectroscopy, energy dispersive X-ray spectroscopy, XPS, cyclic voltammetry and electrochem. impedance spectroscopy. Pt/PSi nanocomposite in carbon ionic liq. electrode (CILE) has synergetic effect on the oxidn. of morphine and codeine. Simultaneous detn. of morphine and codeine were performed using the proposed sensor by means of adsorptive striping voltammetry. Under the optimum conditions, the oxidn. current responses of morphine and codeine were linear in the concn. range of 0.10-25.0 μmol L-1. The detection limits of 30.0 and 20.0 nmol L-1 were achieved for morphine and codeine, resp. The electrochem. sensor has high sensitivity toward the analytes with a good reproducibility (due to the high synergetic activity of Pt nanoparticles and good antifouling properties of the ionic liq.). To check the applicability of the sensor, the proposed sensor was used for the simultaneous detn. of morphine and codeine in biol. fluids with satisfactory results.
- 38Harraz, F. A.; Sakka, T.; Ogata, Y. H. Immersion plating of nickel onto a porous silicon layer from fluoride solutions. Phys. Status Solidi A 2003, 197 (1), 51– 56, DOI: 10.1002/pssa.200306467Google Scholar38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXkt1Ontb8%253D&md5=6a5335861efc34a86fa9dce58941dd94Immersion plating of nickel onto a porous silicon layer from fluoride solutionsHarraz, F. A.; Sakka, T.; Ogata, Y. H.Physica Status Solidi A: Applied Research (2003), 197 (1), 51-56CODEN: PSSABA; ISSN:0031-8965. (Wiley-VCH Verlag GmbH & Co. KGaA)The deposition of nickel (Ni) onto a porous silicon (PS) layer by immersion plating from acidic and alk. fluoride solns. was studied. In an immersion plating bath of simple hydrofluoric acid (HF) of pH 2 contg. Ni ions, no metal deposition was obsd. However, visible metallic Ni was deposited from the ammonium fluoride (NH4F) alk. soln. of pH 8. The different deposition behaviors are discussed from mixed potential theory, etching rate of PS and the state of Ni complex formation. The modified PS layers after the immersion plating were analyzed by x-ray diffraction and XPS. FTIR spectroscopy and SEM were also performed to study the structural changes and characterizations of PS samples after the plating process. A binary PS/Ni nanostructure without Si oxides is successfully achieved from the alk. bath.
- 39Sham, T. K.; Coulthard, I.; Lorimer, J.; Hiraya, A.; Watanabe, M. Reductive deposition of Cu on porous silicon from aqueous solutions: An X-ray absorption study at the Cu L3, 2 edge. Chem. Mater. 1994, 6 (11), 2085– 2091, DOI: 10.1021/cm00047a031Google Scholar39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXms1Cksbs%253D&md5=bf29f76d2d43239fb10b9f4e6268c950Reductive Deposition of Cu on Porous Silicon from Aqueous Solutions: An X-ray Absorption Study at the Cu L3,2 EdgeSham, T. K.; Coulthard, I.; Lorimer, J. W.; Hiraya, A.; Watanabe, M.Chemistry of Materials (1994), 6 (11), 2085-91CODEN: CMATEX; ISSN:0897-4756.The reductive deposition of metallic Cu on porous silicon (PS) surface from aq. soln. of Cu2+(aq) ions is reported. X-ray absorption near-edge structure (XANES) at the Cu L3,2 edge has been used to characterize these samples. The redn. of Cu2+(aq) to Cu occurs readily at room temp. and appears to be controlled by the availability of active sites as well as the concn. of Cu2+(aq) and that only a very thin film of Cu is formed even with concd. solns. The surface of Cu/PS is oxidized when exposed to the ambient atm. The spectroscopic features and the implication of the results are discussed.
- 40Coulthard, I.; Degen, S.; Zhu, Y.-J.; Sham, T. Gold nanoclusters reductively deposited on porous silicon: morphology and electronic structures. Can. J. Chem. 1998, 76 (11), 1707– 1716, DOI: 10.1139/v98-146Google Scholar40https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXhslWmtLo%253D&md5=7a0b739fd52d01ca87ab0e9857c16802Gold nanoclusters reductively deposited on porous silicon: morphology and electronic structuresCoulthard, I.; Degen, S.; Zhu, Y.-J.; Sham, T. K.Canadian Journal of Chemistry (1998), 76 (11), 1707-1716CODEN: CJCHAG; ISSN:0008-4042. (National Research Council of Canada)Using porous silicon as a reducing agent and a substrate, gold complex ions [AuCl4]- were reduced from aq. soln. to produce nanoparticles of gold upon the surface of porous silicon. SEM was used to study the morphol. of the porous silicon layers and the deposits of gold nanoparticles. It is found that prepn. conditions have a profound effect on the morphol. of the deposits, esp. on porous silicon prepd. from a p-type wafer. The gold nanoparticles, varying from micrometric aggregates of clusters of the order of 10 nm, to a distribution of nearly spherical clusters of the order of 10 nm, to strings of ∼10 nm were obsd. and compared to bulk gold metal using x-ray diffraction (XRD), XPS, and x-ray absorption spectroscopy (XAS). These techniques confirm and complement the SEM findings. The potential for this reductive deposition technique is noted.
- 41Wali, L. A.; Hasan, K. K.; Alwan, A. M. An investigation of efficient detection of ultra-low concentration of penicillins in milk using AuNPs/PSi hybrid structure. Plasmonics 2020, 15 (4), 985– 993, DOI: 10.1007/s11468-019-01096-4Google Scholar41https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXjtFSntLo%253D&md5=8b413e075c2c716d9fc2f2c8e160bddaAn Investigation of Efficient Detection of Ultra-Low Concentration of Penicillins in Milk Using AuNPs/PSi Hybrid StructureWali, Layla A.; Hasan, Khulood K.; Alwan, Alwan M.Plasmonics (2020), 15 (4), 985-993CODEN: PLASCS; ISSN:1557-1955. (Springer)In this work, porous silicon (PSi) sample was employed to increase the SERS efficiency for rapid detection of penicillins in spiked milk by developing Au nanoparticles (AuNPs)/PSi hybrid structure. SERS was used to study penicillin G and ampicillin residue in milk. The results show that the AuNPs/PSi hybrid structure is very able to detect penicillins residue in milk with an excellent linear relationship and a correlation coeff. (R2 = 1) in the range of 1 × 10-7 mol/L to 1 × 10-9 mol/L. The highest enhancement factors of penicillin G (2.8 × 108) and of ampicillin (1.2 × 108) with an excellent relative std. deviation (RSD) of 2.69 and 0.93, resp., are obtained at the ultra-low concn. of 1 × 10-9 mol/L. The detection limit of penicillin G and ampicillin is 1 × 10-9 mol/L (equal to 0.33μg/kg and 0.35μg/kg, resp.) which is very lower than the max. residue limit (MRL) of penicillins in milk (4μg/kg) established by the European Union.
- 42Bandarenka, H. V.; Girel, K. V.; Zavatski, S. A.; Panarin, A.; Terekhov, S. N. Progress in the development of SERS-active substrates based on metal-coated porous silicon. Materials 2018, 11 (5), 852, DOI: 10.3390/ma11050852Google Scholar42https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhsVSns77K&md5=6aec61a3fca120907cee21dab09bb815Progress in the development of SERS-active substrates based on metal-coated porous siliconBandarenka, Hanna V.; Girel, Kseniya V.; Zavatski, Sergey A.; Panarin, Andrei; Terekhov, Sergei N.Materials (2018), 11 (5), 852/1-852/20CODEN: MATEG9; ISSN:1996-1944. (MDPI AG)The present work gives an overview of the developments in surface-enhanced Raman scattering (SERS) with metal-coated porous silicon used as an active substrate. We focused this review on the research referenced to SERS-active materials based on porous silicon, beginning from the patent application in 2002 and enclosing the studies of this year. Porous silicon and metal deposition technologies are discussed. Since the earliest studies, a no. of fundamentally different plasmonic nanostructures including metallic dendrites, quasi-ordered arrays of metallic nanoparticles (NPs), and metallic nanovoids have been grown on porous silicon, defined by the morphol. of this host material. SERS-active substrates based on porous silicon have been found to combine a high and well-reproducible signal level, storage stability, cost-effective technol. and handy use. They make it possible to identify and study many compds. including biomols. with a detection limit varying from milli- to femtomolar concns. The progress reviewed here demonstrates the great prospects for the extensive use of the metal-coated porous silicon for bioanal. by SERS-spectroscopy.
- 43Khinevich, N.; Bandarenka, H.; Zavatski, S.; Girel, K.; Tamulevičienė, A.; Tamulevičius, T.; Tamulevičius, S. Porous silicon-A versatile platform for mass-production of ultrasensitive SERS-active substrates. Microporous Mesoporous Mater. 2021, 323, 111204 DOI: 10.1016/j.micromeso.2021.111204Google Scholar43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsVagsrnK&md5=4af03ccf3c5e05d4e35eb161a1ad786aPorous silicon - A versatile platform for mass-production of ultrasensitive SERS-active substratesKhinevich, Nadzeya; Bandarenka, Hanna; Zavatski, Siarhei; Girel, Kseniya; Tamuleviciene, Asta; Tamulevicius, Tomas; Tamulevicius, SigitasMicroporous and Mesoporous Materials (2021), 323 (), 111204CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)A review. Surface-enhanced Raman scattering (SERS) spectroscopy is one of the most prospective methods combining state-of-the-art nanomaterials and optical techniques for highly sensitive express-anal. and detection of org. and bioorg. objects in liqs. and gases. Special programs have been recently started all over the world to bring the SERS-spectroscopy closer to wide implementation in medical diagnostics, forensics, security, monitoring sanitary conditions, etc. Despite outstanding features of SERS-spectroscopy, its effective practical use has been particularly slowed down by moderate reproducibility, non-versatility, and restrictions imposed by com. available SERS-active substrates to measurement and storage regimes. The present reports SERS-active substrates constituted by noble metals' nanoparticles (NPs) and porous silicon (PS), which potentially can be a tool to overcome the above-mentioned limitations. The PS template acts as a highly ordered host nanomaterial for the formation of a variety of metallic nanostructures, which morphol. and optical properties can be easily tuned for the best performance to meet the customer requirements via managing PS synthesis regimes. An indubitable advantage of PS is the compatibility of its fabrication process with basic microelectronics operations and micro-electro mech. systems (MEMS) that make it possible to integrate SERS-active areas in a silicon chip. In contrast to the previously published s in the field, this one covers the most recent results on formation, characterization, and application of PS-based substrates demonstrating prominent SERS-activity that have been achieved for the last decade including modifications with graphene or Bragg structures, detection of mols. at amt. down to attomolar concn. bacteria recognition, etc.
- 44Liu, X.; Cheng, H.; Cui, P. Catalysis by silver nanoparticles/porous silicon for the reduction of nitroaromatics in the presence of sodium borohydride. Appl. Surf. Sci. 2014, 292, 695– 701, DOI: 10.1016/j.apsusc.2013.12.036Google Scholar44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXpsV2k&md5=58dacecc5cb01c5ef3a2f4c0d90b2173Catalysis by silver nanoparticles/porous silicon for the reduction of nitroaromatics in the presence of sodium borohydrideLiu, Xiang; Cheng, Heming; Cui, PingApplied Surface Science (2014), 292 (), 695-701CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)A facile approach of prepg. well-dispersed silver nanoparticles (Ag NPs) which fabricated on surface of porous silicon (PSi) generating Ag NPs/PSi chip and the catalyzes towards redn. of nitro aroms. are described in detail in this work. Aq. silver ions are reduced readily by the surface SiHx (x =1, 2 or 3) species of PSi within dozens of seconds at room temp. The resulted Ag NPs are demonstrated by scanning and transmission electron microscopes, UV-visible spectrum and X-ray powder diffraction. A proposed mechanism of forming Ag NPs on PSi chip is discussed in light of the obsd. phenomena and the analyses of IR and energy dispersive X-ray spectra. The stably porous architecture of PSi and the well-dispersed Ag NPs on PSi surface guarantee the highly catalytic activities of the Ag NPs/PSi chip. The progresses of reducing nitro aroms. catalyzed by the Ag NPs/PSi chip in the presence of sodium borohydride are traced by UV-visible measurements to est. the catalytic performance of the Ag NPs/PSi chip.
- 45Polisski, S.; Goller, B.; Wilson, K.; Kovalev, D.; Zaikowskii, V.; Lapkin, A. In situ synthesis and catalytic activity in CO oxidation of metal nanoparticles supported on porous nanocrystalline silicon. J. Catal. 2010, 271 (1), 59– 66, DOI: 10.1016/j.jcat.2010.02.002Google Scholar45https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXjslGrtb0%253D&md5=b4bbc1860c3ff93f9817a148561255faIn situ synthesis and catalytic activity in CO oxidation of metal nanoparticles supported on porous nanocrystalline siliconPolisski, Sergej; Goller, Bernhard; Wilson, Karen; Kovalev, Dmitry; Zaikowskii, Vladimir; Lapkin, AlexeiJournal of Catalysis (2010), 271 (1), 59-66CODEN: JCTLA5; ISSN:0021-9517. (Elsevier Inc.)The reactive surface of meso-porous, nanocryst. Si was used to synthesize noble metal nanoparticles by in-situ redn. of precursor salt solns. The synthetic method for metal nanoparticle formation was systematically developed; reaction conditions for metal salts redn. were optimized to prep. nanoparticles with controlled size distribution on the order 5-10 nm inside the meso-porous Si template. CO oxidn. was used as a test reaction for synthesized Pt/porous Si catalysts. Sharp reaction light-off was obsd. at ∼120° on optimized catalysts. Catalysts were stable in extended steady-state runs and in catalysts re-use expts. Metal nanoparticles were stable to sintering at elevated temps. ≤1000°. However, following thermal treatment in air, Pt nanoparticles were covered by a SiOx layer and were less active for CO oxidn.
- 46Halim, M.; Tan, W. L.; Abu Bakar, N. H. H.; Abu Bakar, M. Surface characteristics and catalytic activity of copper deposited porous silicon powder. Materials 2014, 7 (12), 7737– 7751, DOI: 10.3390/ma7127737Google Scholar46https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1cflsF2huw%253D%253D&md5=620176015cc04e7a2d4b03e5c8e8041cSurface Characteristics and Catalytic Activity of Copper Deposited Porous Silicon PowderHalim Muhammad Yusri Abdul; Tan Wei Leng; Bakar Noor Hana Hanif Abu; Bakar Mohamad AbuMaterials (Basel, Switzerland) (2014), 7 (12), 7737-7751 ISSN:1996-1944.Porous structured silicon or porous silicon (PS) powder was prepared by chemical etching of silicon powder in an etchant solution of HF: HNO3: H2O (1:3:5 v/v). An immersion time of 4 min was sufficient for depositing Cu metal from an aqueous solution of CuSO4 in the presence of HF. Scanning electron microscopy (SEM) analysis revealed that the Cu particles aggregated upon an increase in metal content from 3.3 wt% to 9.8 wt%. H2-temperature programmed reduction (H2-TPR) profiles reveal that re-oxidation of the Cu particles occurs after deposition. Furthermore, the profiles denote the existence of various sizes of Cu metal on the PS. The Cu-PS powders show excellent catalytic reduction on the p-nitrophenol regardless of the Cu loadings.
- 47Hernández-Montelongo, J.; Fernández-Fierro, C.; Benito-Gómez, N.; Romero-Saez, M.; Parodi, J.; Carmona, E. R.; Recio-Sánchez, G. Hybrid porous silicon/green synthetized Ag microparticles as potential carries for Ag nanoparticles and drug delivery. Mater. Sci. Eng. C 2020, 116, 111183 DOI: 10.1016/j.msec.2020.111183Google Scholar47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXht1CqtL3I&md5=f7068d7e9075e146b7da55704028e77eHybrid porous silicon/green synthetized Ag microparticles as potential carries for Ag nanoparticles and drug deliveryHernandez-Montelongo, Jacobo; Fernandez-Fierro, Cristian; Benito-Gomez, Noelia; Romero-Saez, Manuel; Parodi, Jorge; Carmona, Erico R.; Recio-Sanchez, GonzaloMaterials Science & Engineering, C: Materials for Biological Applications (2020), 116 (), 111183CODEN: MSCEEE; ISSN:0928-4931. (Elsevier B.V.)In the present work, the fabrication of hybrid porous silicon/green synthesized Ag microparticles was shown and the potential use as carriers for Ag nanoparticles and drug delivery was explored. Hybrid microparticles were fabricated by incorporating green synthesized Ag nanoparticles into porous silicon matrix. The main physicochem. characteristics of the hybrid systems were studied by several techniques including UV-vis spectroscopy, TEM, SEM, XRD and XPS. The toxicol. of these hybrid systems was investigated by cell viability, MTT, and comet assays. In addn., the possibility to aggregate different drug to use as drug delivery system was demonstrated by using florfenicol as drug model, due to its importance in salmon industry. The exptl. results showed the potential to use these hybrid systems as carries for drug delivery in salmon industry.
- 48Hernandez, M.; Recio, G.; Martin-Palma, R. J.; Garcia-Ramos, J. V.; Domingo, C.; Sevilla, P. Surface enhanced fluorescence of anti-tumoral drug emodin adsorbed on silver nanoparticles and loaded on porous silicon. Nanoscale Res. Lett. 2012, 7, 364, DOI: 10.1186/1556-276X-7-364Google Scholar48https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsVWhs7rK&md5=3222a6c4f711cb6f04ff0f30dadf773dSurface enhanced fluorescence of anti-tumoral drug emodin adsorbed on silver nanoparticles and loaded on porous siliconHernandez, Margarita; Recio, Gonzalo; Martin-Palma, Raul J.; Garcia-Ramos, Jose V.; Domingo, Concepcion; Sevilla, PazNanoscale Research Letters (2012), 7 (1), 364, 7 pp.CODEN: NRLAAD; ISSN:1556-276X. (Springer)Fluorescence spectra of anti-tumoral drug emodin loaded on nanostructured porous silicon have been recorded. The use of colloidal nanoparticles allowed embedding of the drug without previous porous silicon functionalization and leads to the observation of an enhancement of fluorescence of the drug. Mean pore size of porous silicon matrixes was 60 nm, while silver nanoparticles mean diam. was 50 nm. Atm. and vacuum conditions at room temp. were used to infiltrate emodin-silver nanoparticles complexes into porous silicon matrixes. The drug was loaded after adsorption on metal surface, alone, and bound to bovine serum albumin. Methanol and water were used as solvents. Spectra with 1 μm spatial resoln. of cross-section of porous silicon layers were recorded to observe the penetration of the drug. A max. fluorescence enhancement factor of 24 was obtained when protein was loaded bound to albumin, and atm. conditions of inclusion were used. A better penetration was obtained using methanol as solvent when comparing with water. Complexes of emodin remain loaded for 30 days after prepn. without an apparent degrdn. of the drug, although a decrease in the enhancement factor is obsd. The study reported here constitutes the basis for designing a new drug delivery system with future applications in medicine and pharmacy.
- 49Lin, T.; Zhong, L.; Guo, L.; Fu, F.; Chen, G. Seeing diabetes: visual detection of glucose based on the intrinsic peroxidase-like activity of MoS2 nanosheets. Nanoscale 2014, 6 (20), 11856– 11862, DOI: 10.1039/C4NR03393KGoogle Scholar49https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1ylt7nN&md5=47e5a74f612da163694c3016fe739511Seeing diabetes: visual detection of glucose based on the intrinsic peroxidase-like activity of MoS2 nanosheetsLin, Tianran; Zhong, Liangshuang; Guo, Liangqia; Fu, Fengfu; Chen, GuonanNanoscale (2014), 6 (20), 11856-11862CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Molybdenum disulfide (MoS2) has attracted increasing research interest recently due to its unique phys., optical and elec. properties, correlated with its 2D ultrathin at.-layered structure. Until now, however, great efforts have focused on its applications such as lithium ion batteries, transistors, and hydrogen evolution reactions. Herein, for the first time, MoS2 nanosheets are discovered to possess an intrinsic peroxidase-like activity and can catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a color reaction. The catalytic activity follows the typical Michaelis-Menten kinetics and is dependent on temp., pH, H2O2 concn., and reaction time. Based on this finding, a highly sensitive and selective colorimetric method for H2O2 and glucose detection is developed and applied to detect glucose in serum samples. Moreover, a simple, inexpensive, instrument-free and portable test kit for the visual detection of glucose in normal and diabetic serum samples is constructed by utilizing agarose hydrogel as a visual detection platform.
- 50Masud, M. K.; Kim, J.; Billah, M. M.; Wood, K.; Shiddiky, M. J.; Nguyen, N.-T.; Parsapur, R. K.; Kaneti, Y. V.; Alshehri, A. A.; Alghamidi, Y. G. Nanoarchitectured peroxidase-mimetic nanozymes: mesoporous nanocrystalline α-or γ-iron oxide?. J. Mater. Chem. B 2019, 7 (35), 5412– 5422, DOI: 10.1039/C9TB00989BGoogle Scholar50https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhsFyjurnL&md5=f659d0e439ecbf3fcabe1da2e3c21a3cNanoarchitectured peroxidase-mimetic nanozymes: mesoporous nanocrystalline α- or γ-iron oxide?Masud, Mostafa Kamal; Kim, Jeonghun; Billah, Md. Motasim; Wood, Kathleen; Shiddiky, Mohammad J. A.; Nguyen, Nam-Trung; Parsapur, Rajesh Kumar; Kaneti, Yusuf Valentino; Alshehri, Abdulmohsen Ali; Alghamidi, Yousef Gamaan; Alzahrani, Khalid Ahmed; Adharvanachari, Murugulla; Selvam, Parasuraman; Hossain, Md. Shahriar A.; Yamauchi, YusukeJournal of Materials Chemistry B: Materials for Biology and Medicine (2019), 7 (35), 5412-5422CODEN: JMCBDV; ISSN:2050-7518. (Royal Society of Chemistry)Nanozymes (nanoparticles with enzyme-like properties) have attracted considerable attention in recent years owing to their intrinsic enzyme-like properties and broad application in the fields of ELISA based immunoassay and biosensing. Herein, the authors systematically study the influence of crystal phases (γ-Fe2O3 and α-Fe2O3) of mesoporous iron oxide (IO) on their peroxidase mimetic activity. In addn., the authors also demonstrated the applicability of these mesoporous IOs as nanozymes for detecting the glucose biomarker with a limit of detection (LOD) of 0.9 μM. Mesoporous γ-Fe2O3 shows high nanozyme activities (and magnetism) toward the catalytic oxidn. of chromogenic substances, such as 3,3',5,5'-tetramethylbenzidine (TMB) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)-ABTS, as well as for the colorimetric detection of glucose, compared to that of α-Fe2O3. The authors believe that this in-depth study of crystal structure based nanozyme activity will guide designing highly effective nanozymes based on iron oxide nanostructures for chem. sensing, biosensing and environmental remediation.
- 51Lehninger, A. L.; Nelson, D. L.; Cox, M. M.; Cox, M. M. Lehninger Principles of Biochemistry; Macmillan, 2005.Google ScholarThere is no corresponding record for this reference.
- 52Nabil, M.; Motaweh, H. A. Enhanced thermal stability of promising nano-porous silicon powder. Adv. Nanopart. 2016, 05 (04), 199– 205, DOI: 10.4236/anp.2016.54021Google Scholar52https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtFajsbfE&md5=60b42ee527c33095054ef8aba2651535Enhanced thermal stability of promising nano-porous silicon powderNabil, Marwa; Motaweh, Hussien A.Advances in Nanoparticles (2016), 5 (4), 199-205CODEN: ANDAA6; ISSN:2169-0529. (Scientific Research Publishing, Inc.)A direct synthesis method is introduced to prep. nano-porous silicon-nickel nanocomposite (nPS/Ni) powder for thermal isolation applications. In this paper, we study the thermal stability of nanocomposites consisting of nanoparticles metal incorporated into the pores of a porous silicon by a very simple method. The nickel element is chem. deposited whereas the nanoparticles are pptd. on the pore surfaces. The (nPS) and (nPS/Ni) nano-materials are thermally measured under nitrogen at temps. of 40°C - 1000°C, noticeable, demonstrating better thermal stability of (nPS/Ni) until 900°C than in the case of (nPS) at 600°C. Then, the improving of the thermal stability of the nPS powder is facilitated using it in many applications of the thermal insulation process.
- 53Ren, X.; Song, Y.; Liu, A.; Zhang, J.; Yang, P.; Zhang, J.; An, M. Experimental and theoretical studies of DMH as a complexing agent for a cyanide-free gold electroplating electrolyte. RSC Adv. 2015, 5 (80), 64997– 65004, DOI: 10.1039/C5RA13140EGoogle Scholar53https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFylu7%252FM&md5=68a18a0d373d6cc0cde2f65c1c34d390Experimental and theoretical studies of DMH as a complexing agent for a cyanide-free gold electroplating electrolyteRen, Xuefeng; Song, Ying; Liu, Anmin; Zhang, Jie; Yang, Peixia; Zhang, Jinqiu; An, MaozhongRSC Advances (2015), 5 (80), 64997-65004CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)In this study, a cyanide-free gold electroplating electrolyte using 5,5-dimethylhydantoin (DMH) as a complexing agent was introduced. A golden bright gold electrodeposit with smooth and compact surface was obtained from the introduced cyanide-free gold electroplating electrolyte. The results of SEM (SEM) measurements confirmed that the golden bright gold electrodeposit possesses an excellent leveling capability as well as smooth and compact morphol. The cryst. structure of the gold electrodeposits was characterized by X-ray diffraction (XRD) anal. Computational chem. was employed to provide an insight view of the reason for selecting DMH among the various hydantoin derivs. as the complexing agent for the introduced cyanide-free gold electroplating electrolyte. Quantum chem. calcns. were employed to study the electronic properties and orbital information of the investigated complexing agents. The adsorption interactions between these complexing agents and the metal surfaces were investigated by mol. dynamic (MD) simulations. Consequently, the results of these theor. studies revealed that DMH was selected among the various hydantoin derivs. as the complexing agent for the introduced cyanide-free gold electroplating electrolyte due to its strong electron donating abilities and high adsorption energies on the metal surfaces.
- 54Boriachek, K.; Masud, M. K.; Palma, C.; Phan, H.-P.; Yamauchi, Y.; Hossain, M. S. A.; Nguyen, N.-T.; Salomon, C.; Shiddiky, M. J. Avoiding pre-isolation step in exosome analysis: direct isolation and sensitive detection of exosomes using gold-loaded nanoporous ferric oxide nanozymes. Anal. Chem. 2019, 91 (6), 3827– 3834, DOI: 10.1021/acs.analchem.8b03619Google Scholar54https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXivVOit7k%253D&md5=85486a32ff7b3fa135c4a19926746319Avoiding Pre-Isolation Step in Exosome Analysis: Direct Isolation and Sensitive Detection of Exosomes Using Gold-Loaded Nanoporous Ferric Oxide NanozymesBoriachek, Kseniia; Masud, Mostafa Kamal; Palma, Carlos; Phan, Hoang-Phuong; Yamauchi, Yusuke; Hossain, Md. Shahriar A.; Nguyen, Nam-Trung; Salomon, Carlos; Shiddiky, Muhammad J. A.Analytical Chemistry (Washington, DC, United States) (2019), 91 (6), 3827-3834CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)Most of the current exosome-anal. strategies are time-consuming and largely dependent on com. extn. kit-based preisolation step, which requires extensive sample manipulations, costly isolation kits, reagents, tedious procedures, and sophisticated equipment and is prone to bias/artifacts. Herein we introduce a simple method for direct isolation and subsequent detection of a specific population of exosomes using an engineered superparamagnetic material with multifunctional properties, namely, gold-loaded ferric oxide nanocubes (Au-NPFe2O3NC). In this method, the Au-NPFe2O3NC were initially functionalized with a generic tetraspanin (exosomes-assocd.) antibody (i.e., CD63) and dispersed in sample fluids where they work as "dispersible nanocarriers" to capture the bulk population of exosomes. After magnetic collection and purifn., Au-NPFe2O3NC-bound exosomes were transferred to the tissue-specific, antibody-modified, screen-printed electrode. As a proof of principle, we used a specific placental marker, placenta alk. phosphatase (PLAP), to detect exosomes secreted from placental cells. The peroxidase-like activity of Au-NPFe2O3NC was then used to accomplish an ELISA-based sensing protocol for naked-eye observation along with UV-visible and electrochem. detection of PLAP-specific exosomes present in placental cell-conditioned media. We demonstrated excellent agreement in anal. performance for the detection of placental cell-derived exosomes (i.e., linear dynamic range, 103-107 exosomes/mL; limit of detection, 103 exosomes/mL; relative std. deviation (%RSD) of <5.5% for n = 3) using with and without com. "total exosome isolation kit"-based preisolation step. We envisage that this highly sensitive, rapid, and inexpensive assay could be useful in quantifying specific populations of exosomes for various clin. applications, focusing on pregnancy complications.
- 55Gurol, M. D.; Lin, S.-S. Hydrogen peroxide/iron oxide-induced catalytic oxidation of organic compounds. J. Adv. Oxid. Technol. 2002, 5 (2), 147– 154, DOI: 10.1515/jaots-2002-0204Google Scholar55https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38Xmt1Ohu7o%253D&md5=443bf5a3066079b82f95f2e1ebceeb41Hydrogen peroxide/iron oxide-induced catalytic oxidation of organic compoundsGurol, Mirat D.; Lin, Shu-SungJournal of Advanced Oxidation Technologies (2002), 5 (2), 147-154CODEN: JAOTFT; ISSN:1203-8407. (Science & Technology Network, Inc.)This paper describes a novel heterogeneous catalytic oxidn. process involving the use of hydrogen peroxide (H2O2) with granular size iron oxide particles (α-FeOOH) in aq. phase. The generation of hydroxyl radical (•OH) in the process is demonstrated through the use of a probe chem., n-chlorobutane (BuCl). Based on the exptl. evidence, it is concluded that the •OH, which is produced through the interaction of H2O2 with the surface sites, reacts with solutes adsorbed on the goethite surface, causing oxidn. of the org. compds. The generation rate of •OH increases slightly with increasing pH in the range of 5-9. The oxidn. rate of BuCl by •OH is relatively insensitive to the level of bicarbonate ion in subject water due to low affinity of bicarbonate for the surface. Phosphate, on the other hand, inhibits the oxidn. rate by preferential adsorption on the surface. This new process provides a viable alternative to the existing oxidn. technologies, esp. when water has high alky., and/or it is desired to selectively oxidize target compds. that have high affinity for the surface.
- 56Motherwell, W.; Bingham, M.; Six, Y. Recent progress in the design and synthesis of artificial enzymes. Tetrahedron 2001, 57 (22), 4663– 4686, DOI: 10.1016/S0040-4020(01)00288-5Google Scholar56https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXjslehsrk%253D&md5=bdf403f3b4b8bd16e76a6a5c56e7c28bRecent progress in the design and synthesis of artificial enzymesMotherwell, W. B.; Bingham, M. J.; Six, Y.Tetrahedron (2001), 57 (22), 4663-4686CODEN: TETRAB; ISSN:0040-4020. (Elsevier Science Ltd.)A review with 111 refs., which details recent progress in the design and synthesis of artificial enzymes, such as cyclodextrins and catalytic antibodies. Particular emphasis is given to some of the more recent developments in 'selection approaches' toward enzyme mimics. Furthermore, dynamic combinatorial libraries and related research is described with ref. to possible applications in the field of artificial enzymes.
- 57Chen, W.; Chen, J.; Liu, A. L.; Wang, L. M.; Li, G. W.; Lin, X. H. Peroxidase-like activity of cupric oxide nanoparticle. ChemCatChem 2011, 3 (7), 1151– 1154, DOI: 10.1002/cctc.201100064Google Scholar57https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXotFyjsbg%253D&md5=f3a88cea985308497b69df6a881d410bPeroxidase-Like Activity of Cupric Oxide NanoparticleChen, Wei; Chen, Juan; Liu, Ai-Lin; Wang, Li-Man; Li, Guang-Wen; Lin, Xin-HuaChemCatChem (2011), 3 (7), 1151-1154CODEN: CHEMK3; ISSN:1867-3880. (Wiley-VCH Verlag GmbH & Co. KGaA)It is well known that peroxidase can catalyze the oxidn. of a peroxidase substrate by hydrogen peroxide to produce a color change. Upon the addn. of cupric oxide nanoparticles (CuO NPs) to the peroxidase substrate TMB in the presence of H2O2, a blue color product can be formed with a max. absorbance at A = 652nm, indicating that cupric oxide nanoparticles have peroxidase-like catalytic activity.
- 58Pankhurst, Q. A.; Thanh, N.; Jones, S.; Dobson, J. Progress in applications of magnetic nanoparticles in biomedicine. J. Phys. D: Appl. Phys. 2009, 42 (22), 224001 DOI: 10.1088/0022-3727/42/22/224001Google Scholar58https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsFeksr%252FM&md5=b18381643f157f66a155154560582b25Progress in applications of magnetic nanoparticles in biomedicinePankhurst, Q. A.; Thanh, N. K. T.; Jones, S. K.; Dobson, J.Journal of Physics D: Applied Physics (2009), 42 (22), 224001/1-224001/15CODEN: JPAPBE; ISSN:0022-3727. (Institute of Physics Publishing)A review and progress report on a selection of scientific, technol., and com. advances in the biomedical applications of magnetic nanoparticles since 2003. Particular attention is paid to (1) magnetic actuation for in vitro nonviral transfection and tissue engineering and in vivo drug delivery and gene therapy, (2) recent clin. results for magnetic hyperthermia treatments of brain and prostate cancer via direct injection, and continuing efforts to develop new agents suitable for targeted hyperthermia following i.v. injection, and (3) developments in medical sensing technologies involving a new generation of magnetic resonance imaging contrast agents, and the invention of magnetic particle imaging as a new modality. Ongoing prospects are also discussed.
- 59Dutta, A. K.; Maji, S. K.; Srivastava, D. N.; Mondal, A.; Biswas, P.; Paul, P.; Adhikary, B. Peroxidase-like activity and amperometric sensing of hydrogen peroxide by Fe2O3 and Prussian Blue-modified Fe2O3 nanoparticles. J. Mol. Catal. A 2012, 360, 71– 77, DOI: 10.1016/j.molcata.2012.04.011Google Scholar59https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XotVajtbw%253D&md5=180d1bace63f4efcc8031595eb156372Peroxidase-like activity and amperometric sensing of hydrogen peroxide by Fe2O3 and Prussian Blue-modified Fe2O3 nanoparticlesDutta, Amit Kumar; Maji, Swarup Kumar; Srivastava, Divesh N.; Mondal, Anup; Biswas, Papu; Paul, Parimal; Adhikary, BibhutoshJournal of Molecular Catalysis A: Chemical (2012), 360 (), 71-77CODEN: JMCCF2; ISSN:1381-1169. (Elsevier B.V.)Nano-sized crystals of iron oxide (Fe2O3) was synthesized from a single-source precursor complex [Fe3(μ3-O)(O2CCH2Cl)6(H2O)3]NO3·H2O by solvothermal process. Afterward it was chem. modified with electro-active Prussian Blue (PB). The resulting Fe2O3 and PB-Fe2O3 nanoparticles (NPs) were characterized by x-ray diffraction anal. (XRD), TEM, UV-visible and IR spectroscopic techniques. Structural analyses showed that the av. diam. of hexagonal Fe2O3 (maghemite) and PB-Fe2O3 NPs are 40 and 46 nm, resp. The as-synthesized nanocomposite (PB-Fe2O3 NPs) showed superior catalytic activity toward oxidn. of peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in presence of H2O2 and follow typical Michaelis-Menten kinetics. Also, the nanocomposite, immobilized on surface of a glassy carbon electrode (GCE), exhibited electrocatalytic activity toward redn. of hydrogen peroxide and can be used for its amperometric detection.
- 60Wei, H.; Wang, E. Fe3O4 magnetic nanoparticles as peroxidase mimetics and their applications in H2O2 and glucose detection. Anal. Chem. 2008, 80 (6), 2250– 2254, DOI: 10.1021/ac702203fGoogle Scholar60https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXit1Gqu7c%253D&md5=c381fb01daf41a50573d097f28d41396Fe3O4 Magnetic Nanoparticles as Peroxidase Mimetics and Their Applications in H2O2 and Glucose DetectionWei, Hui; Wang, ErkangAnalytical Chemistry (Washington, DC, United States) (2008), 80 (6), 2250-2254CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)Artificial enzyme mimetics are a current research interest because natural enzymes bear some serious disadvantages, such as their catalytic activity can be easily inhibited and they can be digested by proteases. A very recent study reported by L. Z. Gao et al. (2007) has proven that Fe3O4 magnetic nanoparticles (MNPs) exhibit an intrinsic enzyme mimetic activity similar to that found in natural peroxidases, though MNPs are usually thought to be biol. and chem. inert. In the present work, the authors just make use of the novel properties of Fe3O4 MNPs as peroxidase mimetics to detect H2O2. The Fe3O4 MNPs were prepd. via a copptn. method. The as-prepd. Fe3O4 MNPs were then used to catalyze the oxidn. of a peroxidase substrate 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) by H2O2 to the oxidized colored product which provides a colorimetric detection of H2O2. As low as 3 × 10-6 mol/L H2O2 could be detected with a linear range from 5 × 10-6 to 1 × 10-4 mol/L via the authors' method. More importantly, a sensitive and selective method for glucose detection was developed using glucose oxidase (GOx) and the as-prepd. Fe3O4 MNPs. The detection platforms for H2O2 and glucose developed in the present work not only further confirmed that the Fe3O4 MNPs possess intrinsic peroxidase-like activity but also showed great potential applications in varieties of simple, robust, and easy-to-make anal. approaches in the future.
- 61Karaseva, E. I.; Losev, Y. P.; Metelitsa, D. Peroxidase-catalyzed Oxidation of 3, 3″, 5, 5″-Tetramethylbenzidine in the Presence of 2, 4-Dinitrosoresorcinol and Polydisulfide Derivatives of Resorcinol and 2, 4-Dinitrosoresorcinol. Russ. J. Bioorg. Chem. 2002, 28 (2), 128– 135, DOI: 10.1023/A:1015069424251Google Scholar61https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XjtlWmsbg%253D&md5=da12696dae5f1453c1d907a9695664efPeroxidase-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine in the presence of 2,4-dinitrosoresorcinol and polydisulfide derivatives of resorcinol and 2,4-dinitrosoresorcinolKaraseva, E. I.; Losev, Yu. P.; Metelitsa, D. I.Russian Journal of Bioorganic Chemistry (Translation of Bioorganicheskaya Khimiya) (2002), 28 (2), 128-135CODEN: RJBCET; ISSN:1068-1620. (MAIK Nauka/Interperiodica Publishing)A comparative study of the kinetics of peroxidase-catalyzed oxidn. of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of 2,4-dinitrosoresorcinol (DNR), its polydisulfide deriv. [poly(DNRDS)], and resorcinol polydisulfide [poly(RDS)], substances that competitively inhibit the formation of TMB conversion product, was carried out. The inhibition consts. Ki for DNR, poly(DNRDS), and poly(RSD) were detd. at 20° and pH 6.4 to be 110, 13.5, and 0.78 μM, resp. The stoichiometric coeffs. of inhibition were calcd. to be 0.38 and 76 for poly(DNRDS) and poly(RDS), resp. In the pH range 6.4-7.0, the initial rates of the peroxidative oxidn. of TMB, and its mixts. with DNR and poly(DNRDS) and the Ki, value for poly(RDS) substantially decreased with increasing pH. The kinetic parameters of poly(RDS) (Ki 0.22-0.78 μM and f76) suggest that it is the most efficient inhibitor of peroxidase oxidn. of TMB: in micromolar concns., it completely stops this process and can be used in EIA.
- 62Lineweaver, H.; Burk, D. The determination of enzyme dissociation constants. J. Am. Chem. Soc. 1934, 56 (3), 658– 666, DOI: 10.1021/ja01318a036Google Scholar62https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaA2cXisF2ltg%253D%253D&md5=6bacac43540e56d2a3a3955b2911a12dDetermination of enzyme dissociation constantsLineweaver, Hans; Burk, DeanJournal of the American Chemical Society (1934), 56 (), 658-66CODEN: JACSAT; ISSN:0002-7863.Graphical methods involving const. slopes and straight-line extrapolations have been developed for testing and interpreting kinetic data and for detg. dissocn. consts. of enzyme-substrate and enzyme-inhibitor compds. and other related consts. when the data are found to be consistent with an assigned mechanism. Representative analyses are given for invertase, raffinase, amylase, citric dehydrogenase, catalase, oxygenase, esterase and lipase, involving substrate activation, substrate inhibition, general competitive and noncompetitive inhibition, steady states and reactions of various orders. The various methods described are applicable to gen. chem. catalysis, homogeneous or heterogeneous.
- 63Ma, Z.-Z.; Wang, Y.-S.; Liu, B.; Jiao, H.; Xu, L. A non–enzymatic electrochemical sensor of Cu@Co–MOF composite for glucose detection with high sensitivity and selectivity. Chemosensors 2022, 10 (10), 416, DOI: 10.3390/chemosensors10100416Google Scholar63https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XislGgur3M&md5=0c045dbc093894ae44d00c561ae7537cA Non-Enzymatic Electrochemical Sensor of Cu@Co-MOF Composite for Glucose Detection with High Sensitivity and SelectivityMa, Zhen-Zhen; Wang, Yue-Shu; Liu, Bing; Jiao, Huan; Xu, LingChemosensors (2022), 10 (10), 416CODEN: CHEMQ9; ISSN:2227-9040. (MDPI AG)A 3D cobalt metal-org. framework (Co-MOF), [Co3(BDC)3(DMU)2], was utilized to prep. Cu@Co-MOF composite in a deposition-redn. process. Cu@Co-MOF/GCE (GCE = glassy carbon electrode) electrode was prepd. by "drop-coating" method. Cu@Co-MOF/GCE shows excellent electrocatalytic activity for Glu detection. The chronoamperometric response of Cu@Co-MOF/GCE to Glu concn. (CGlu) displays linear relationships in two CGlu sections with calcd. sensitivities of 282.89 μA mM-1 cm-2 within 0.005-0.4 mM Glu and 113.15 μA mM-1 cm-2 within 0.4-1.8 mM Glu. The detection limit is calcd. as 1.6 μM at S/N = 3. Cu@Co-MOF/GCE also exhibits a rapid current response, high anti-interference, stability, and repeatability to Glu detection. Cu@Co-MOF/GCE was applied to detect Glu in human serum and orange juice. All found CGlu are very close to those added CGlu with low RSDs and high recoveries. Cu@Co-MOF/GCE as a non-enzymic electrochem. sensor of Glu has high sensitivity, selectivity, accuracy, and reliability.
- 64Altahan, M. F.; Esposito, M.; Bogner, B.; Achterberg, E. P. The Use of Bi-Potentiostat as a Simple and Accurate Electrochemical Approach for the Determination of Orthophosphate in Seawater. Sensors 2023, 23 (4), 2123, DOI: 10.3390/s23042123Google Scholar64https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXkt1Chtb0%253D&md5=9fa256d3706f1bddf2a1a20bca38cfd9The Use of Bi-Potentiostat as a Simple and Accurate Electrochemical Approach for the Determination of Orthophosphate in SeawaterAltahan, Mahmoud Fatehy; Esposito, Mario; Bogner, Boie; Achterberg, Eric P.Sensors (2023), 23 (4), 2123CODEN: SENSC9; ISSN:1424-8220. (MDPI AG)Autonomous on-site monitoring of orthophosphate (PO43-), an important nutrient for primary prodn. in natural waters, is urgently needed. Here, we report on the development and validation of an on-site autonomous electrochem. analyzer for PO43- in seawater. The approach is based on the use of flow injection anal. in conjunction with a dual electrochem. cell i.e., a bi-potentiostat detector (FIA-DECD) that uses two working electrodes sharing the same ref. and counter electrode. The two working electrodes are used (molybdate/carbon paste electrode (CPE) and CPE) to correct for matrix effects. Optimization of squarewave voltammetry parameters (including step potential, amplitude, and frequency) was undertaken to enhance anal. sensitivity. Possible interferences from non-ionic surfactants and humic acid were investigated. The limit of quantification in artificial seawater (30 g/L NaCl, pH 0.8) was 0.014μM for a linear concn. range of 0.02-3μM. The system used a Python script for operation and data processing. The analyzer was tested for ship-board PO43- detn. during a four-day research cruise in the North Sea. The analyzer successfully measured 34 samples and achieved a good correlation (Pearson' R = 0.91) with discretely collected water samples analyzed using a lab.-based colorimetric ref. analyzer.
- 65Pensa, E.; Cortés, E.; Corthey, G.; Carro, P.; Vericat, C.; Fonticelli, M. H.; Benitez, G.; Rubert, A. A.; Salvarezza, R. C. The chemistry of the sulfur–gold interface: in search of a unified model. Acc. Chem. Res. 2012, 45 (8), 1183– 1192, DOI: 10.1021/ar200260pGoogle Scholar65https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XksVKns78%253D&md5=02c8627b2ed34cd4c98cf51fd8dbfe91The Chemistry of the Sulfur-Gold Interface: In Search of a Unified ModelPensa, Evangelina; Cortes, Emiliano; Corthey, Gaston; Carro, Pilar; Vericat, Carolina; Fonticelli, Mariano H.; Benitez, Guillermo; Rubert, Aldo A.; Salvarezza, Roberto C.Accounts of Chemical Research (2012), 45 (8), 1183-1192CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)A review. Over the last three decades, self-assembled mol. films on solid surfaces have attracted widespread interest as an intellectual and technol. challenge to chemists, physicists, materials scientists, and biologists. A variety of technol. applications of nanotechnol. rely on the possibility of controlling topol., chem., and functional features at the mol. level. Self-assembled monolayers (SAMs) composed of chemisorbed species represent fundamental building blocks for creating complex structures by a bottom-up approach. These materials take advantage of the flexibility of org. and supramol. chem. to generate synthetic surfaces with well-defined chem. and phys. properties. These films already serve as structural or functional parts of sensors, biosensors, drug-delivery systems, mol. electronic devices, protecting capping for nanostructures, and coatings for corrosion protection and tribol. applications. Thiol SAMs on gold are the most popular mol. films because the resulting oxide-free, clean, flat surfaces can be easily modified both in the gas phase and in liq. media under ambient conditions. In particular, researchers have extensively studied SAMs on Au(111) because they serve as model systems to understand the basic aspects of the self-assembly of org. mols. on well-defined metal surfaces. Also, great interest has arisen in the surface structure of thiol-capped gold nanoparticles (AuNPs) because of simple synthesis methods that produce highly monodisperse particles with controllable size and a high surface/vol. ratio. These features make AuNPs very attractive for technol. applications in fields ranging from medicine to heterogeneous catalysis. In many applications, the structure and chem. of the sulfur-gold interface become crucial since they control the system properties. Therefore, many researchers have focused on understanding of the nature of this interface on both planar and nanoparticle thiol-covered surfaces. However, despite the considerable theor. and exptl. efforts made using various sophisticated techniques, the structure and chem. compn. of the sulfur-gold interface at the at. level remains elusive. In particular, the search for a unified model of the chem. of the S-Au interface illustrates the difficulty of detg. the surface chem. at the nanoscale. This Account provides a state-of-the-art anal. of this problem and raises some questions that deserve further investigation.
- 66Krüger, D.; Rousseau, R.; Fuchs, H.; Marx, D. Towards “mechanochemistry”: mechanically induced isomerizations of thiolate–gold clusters. Angew. Chem., Int. Ed. 2003, 42 (20), 2251– 2253, DOI: 10.1002/anie.200351000Google ScholarThere is no corresponding record for this reference.
- 67Huang, Z.; Chen, F.; Bennett, P. A.; Tao, N. Single molecule junctions formed via Au– thiol contact: stability and breakdown mechanism. J. Am. Chem. Soc. 2007, 129, 13225– 13231, DOI: 10.1021/ja074456tGoogle Scholar67https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtFWgur3N&md5=223b6654a07c908a0546491e1bfb44e2Single Molecule Junctions Formed via Au-Thiol Contact: Stability and Breakdown MechanismHuang, Zhifeng; Chen, Fang; Bennett, Peter A.; Tao, NongjianJournal of the American Chemical Society (2007), 129 (43), 13225-13231CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)The stability and breakdown mechanism of a single mol. covalently bound to two Au electrodes via Au-S bonds were studied at room temp. The distance over which a mol. junction can be stretched before breakdown was measured using a scanning tunneling microscopy break junction approach as a function of stretching rate. At low stretching rates, the stretching distance is small and independent of stretching rate. Above a certain stretching rate, it increases linearly with the logarithm of stretching rate. At very high stretching rates, the stretching distance reaches another plateau and becomes insensitive to the stretching rate again. The three regimes are well described by a thermodn. bond-breaking model. A comparative study of Au-Au at. point contacts indicates that the breakdown of the mol. junctions takes place at Au-Au bonds near the mol.-electrode contact. By fitting the exptl. data with the model, the lifetime and binding energy were extd. Both quantities are found to have broad distributions, owing to large variations in the mol.-electrode contact geometry. Although the mol. junctions are short-lived on av., certain contact geometries are considerably more stable. Several types of stochastic fluctuations were obsd. in the conductance of the mol. junctions, which are attributed to the at. level rearrangement of the contact geometry, and bond breakdown and reformation processes. The possibility of bond reformation increases the apparent lifetime of the mol. junctions.
- 68Wang, W.; Rusin, O.; Xu, X.; Kim, K. K.; Escobedo, J. O.; Fakayode, S. O.; Fletcher, K. A.; Lowry, M.; Schowalter, C. M.; Lawrence, C. M. Detection of homocysteine and cysteine. J. Am. Chem. Soc. 2005, 127 (45), 15949– 15958, DOI: 10.1021/ja054962nGoogle Scholar68https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtFalu7rP&md5=c572a5b02956af7dbc6b4fb551651fc0Detection of Homocysteine and CysteineWang, Weihua; Rusin, Oleksandr; Xu, Xiangyang; Kim, Kyu Kwang; Escobedo, Jorge O.; Fakayode, Sayo O.; Fletcher, Kristin A.; Lowry, Mark; Schowalter, Corin M.; Lawrence, Candace M.; Fronczek, Frank R.; Warner, Isiah M.; Strongin, Robert M.Journal of the American Chemical Society (2005), 127 (45), 15949-15958CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)At elevated levels, homocysteine (Hcy) is a risk factor for cardiovascular diseases, Alzheimer's disease, neural tube defects, and osteoporosis. Both Hcy and cysteine (Cys) are linked to neurotoxicity. The biochem. mechanisms by which Hcy and Cys are involved in disease states are relatively unclear. Herein, the authors describe simple methods for detecting either Hcy or Cys in the visible spectral region with the highest selectivity reported to date without using biochem. techniques or preparative sepns. Simple methods and readily available reagents allow for the detection of Cys and Hcy in the range of their physiol. relevant levels. New HPLC postcolumn detection methods for biol. thiols are reported. The potential biomedical relevance of the chem. mechanisms involved in the detection of Hcy is described.
- 69Han, H.; Wang, F.; Chen, J.; Li, X.; Fu, G.; Zhou, J.; Zhou, D.; Wu, W.; Chen, H. Changes in biothiol levels are closely associated with alzheimer’s disease. J. Alzheimer’s Dis. 2021, 82 (2), 527– 540, DOI: 10.3233/JAD-210021Google Scholar69https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhs1Wnt7zM&md5=ba2df8941bd7722a558c37f2e47f3973Changes in Biothiol Levels Are Closely Associated with Alzheimer's DiseaseHan, Hui; Wang, Feng; Chen, Juanjuan; Li, Xingxing; Fu, Gaoqing; Zhou, Jiawei; Zhou, Dongsheng; Wu, Wei; Chen, HaiminJournal of Alzheimer's Disease (2021), 82 (2), 527-540CODEN: JADIF9; ISSN:1387-2877. (IOS Press)Serum homocysteine (Hcy) level is considered to be an important biomarker for Alzheimer's disease (AD); however, the status of Hcy in brain tissue, and the assocn. between brain and serum levels of Hcy in AD patients remain unclear. We aimed to examine whether the changes of three thiols are consistent in serum of AD patients and the brain of APP/PS1 mice, and to verify the effectiveness of Hcy as a biomarker for early AD detection. The levels of Hcy, cysteine (Cys), and glutathione (GSH) in Aβ1-42-treated PC12 cells, the brain and hippocampus of APP/PS1 mouse, and the serum of AD patients were evaluated using Et (E)-3-(9-chloro-11-oxo-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f] pyrido [3,2,1 -ij] quinolin-10-yl)-2-cyanoacrylate (Probe 1) and ELISA assay or LC-MS. Measurement by Probe 1 revealed a significant increase in Hcy level, and a decrease in Cys and GSH levels in Aβ1-42-treated PC12 cells and the serum of AD patients. The hippocampus and whole brain of APP/PS1 mice also showed a significant increase in Hcy level alongside the accumulation of age-related AD symptoms. The upregulation of Hcy and the downregulation of Cys and GSH were reversed in the Aβ1-42-treated PC12 cells and the brain of APP/PS1 mice when supplemented with VB6. Changes in Hcy, Cys, and GSH levels in the brain of APP/PS1 mice and Aβ1-42-treated PC12 cells were obsd. in situ with a new fluorescent probe, which were consistent with the abnormal changes in Hcy, Cys, and GSH levels in the serum of AD patients. VB6 supplementation was successful in ameliorating abnormal increases in Hcy levels.
- 70Chen, Z.; Sun, Q.; Yao, Y.; Fan, X.; Zhang, W.; Qian, J. Highly sensitive detection of cysteine over glutathione and homo-cysteine: new insight into the Michael addition of mercapto group to maleimide. Biosens. Bioelectron. 2017, 91, 553– 559, DOI: 10.1016/j.bios.2017.01.013Google Scholar70https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFOgsb8%253D&md5=b6653d320033dce5eb67b7604d66473dHighly sensitive detection of cysteine over glutathione and homo-cysteine: New insight into the Michael addition of mercapto group to maleimideChen, Zhaoyang; Sun, Qian; Yao, Yuhua; Fan, Xiaoxiang; Zhang, Weibing; Qian, JunhongBiosensors & Bioelectronics (2017), 91 (), 553-559CODEN: BBIOE4; ISSN:0956-5663. (Elsevier B.V.)A fluorescence "off-on" probe CMP for thiols was designed with coumarin as the fluorophore and maleimide as the receptor. The fluorescence of the coumarin was quenched through photoinduced electron transfer (PET) from the fluorophore to maleimide group. The Michael addn. of the mercapto group toward maleimide formed a thioether with relatively weak fluorescence. The intramol. nucleophilic substitution of amino group in cysteine (Cys) to alkylthio produced a much stronger fluorescent amino adduct, which was supported by UPLC-MS and NMR titrn. The above sensing mechanism ensured CMP a highly sensitive probe toward Cys over GSH and Hcy. The fluorescence intensity at 495 nm was linear with Cys concn. over the range of 0-10μM with a detection limit of 14 nM and a rapid response time of 20 min. High selectivity and good competition of the probe toward thiols over other biol. relevant species enabled us to monitor mercapto-contg. proteins as well as fluorescence imaging Cys in living cells.
Cited By
Click to copy section linkSection link copied!
This article has not yet been cited by other publications.
Article Views
559
Altmetric
4
Citations
-
Learn about these metrics
Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.
Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.
The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.
Recommended Articles
Nanozymes: Classification, Catalytic Mechanisms, Activity Regulation, and Applications
Exploring the Specificity of Nanozymes
Natural Enzyme-Inspired Design of the Single-Atom Cu Nanozyme as Dual-Enzyme Mimics for Distinguishing Total Antioxidant Capacity and the Ascorbic Acid Level
Mechanism behind the Controlled Generation of Liquid Metal Nanoparticles by Mechanical Agitation
Nanozymes Inspired by Natural Enzymes
Abstract
Figure 1
Figure 1. Illustration of the peroxidase-mimicking activity of the on-demand activated AuNP-pSi nanozymes for the oxidation of TMB in the presence of H2O2 in a stepwise manner. pSi (light-yellow) was mixed with Au3+ solution to spontaneously produce AuNP-pSi (light-red), which shows a strong TMB oxidation capacity in the presence of H2O2 (blue).
Figure 2
Figure 2. TEM images and digital photographs of (a) a cross-sectional view of a pSi particle, with the inset showing the high-magnification top view of a single particle. The vertically running pores of pSi are visible in the TEM images. The scale bar is 200 nm, while for inset it is 100 nm. The inset also shows a digital photograph of the pSi suspension at 8 mg/mL concentration. TEM images and digital photographs of AuNP-pSi nanohybrids at different pSi:Au (v:v) ratios. (b) TEM image of AuNP-pSi prepared with 4:1 pSi:Au ratio with inset showing a digital photograph of the corresponding sample. The scale bar is 250 nm. (c) TEM image of AuNP-pSi prepared with 1:1 pSi:Au ratio with inset showing a digital photograph of the same sample. The scale bar is 100 nm. (d) TEM image of AuNP-pSi prepared with 1:4 pSi:Au ratio with inset showing a digital photograph of that sample. The scale bar is 200 nm. (e–g) TEM-EDS elemental mapping of Si for AuNP-pSi prepared from (e) 4:1 pSi:Au, (f) 1:1 pSi:Au, and (g) 1:4 pSi:Au ratios. TEM-EDS elemental mapping of Au for AuNPs-pSi prepared from (h) 4:1 pSi:Au, (i) 1:1 pSi:Au, and (j) 1:4 pSi:Au ratios.
Figure 3
Figure 3. UV–vis absorbance at 652 nm for TMB upon oxidation with the AuNP-pSi nanozyme under different conditions. (a) UV–vis spectra for (i) AuNP-pSi, (ii) AuNP-pSi + H2O2, and (iii) AuNP-pSi+H2O2 + TMB. The plasmonic resonance around 560 nm in (ii) can be attributed to AuNPs in the nanohybrid, and a prominent peak appearing at around 652 nm in (iii) is attributed to the oxidized form of TMB formed after reaction with the AuNP-pSi nanozyme. (b) Effects of different ratios of pSi:Au (v:v) when the concentration of the pSi suspension was 8 mg/mL and the Au(III) solution was 10 mM. (c) Effect of the operating pH tested on a 1:1 pSi:Au (v:v) sample. (d) Effect of the working temperature tested on the 1:1 pSi:Au (v:v) sample. (e) TMB oxidation activity of AuNP-pSi measured in the absence and presence of a hydroxide radical scavenger (ascorbic acid; AA; 5 mM). The activity is normalized to the control without AA. Ascorbic acid scavenger absorbs the hydroxyl radical, resulting in lower absorbance than that of the control (AuNP-pSi). (f) Fluorescence spectra of 2-hydroxyterephthalic acid (excited at 315 nm) in the presence of the AuNP-pSi nanozyme at concentrations ranging from 16 to 160 μg. (g) Nanozyme activity retention of AuNP-pSi (red bar) and HRP (green bar) after incubation at different temperatures (40, 60, 80, and 100 °C) for 5 min. (h) Long-term storage stability of the AuNP-pSi nanozyme represented in terms of activity to oxidize TMB. The activity is normalized to a AuNP-pSi nanozyme sample prepared from freshly etched pSi particles and Au(III) solution. These experiments were carried out at 25 °C in 0.2 M NaOAc buffer (pH 3.5) reaction mixture containing 700 mM H2O2 and 1000 μM TMB. Error bars represent the standard deviation of three measurements.
Figure 4
Figure 4. Steady-state kinetic study of AuNP-pSi nanozymes. The reaction rate was tested by tuning the concentrations of (a) H2O2 and (b) TMB. (c) The Lineweaver–Burk plot obtained by altering the concentration of H2O2 (100–1000 mM) with a fixed amount of TMB (1000 μM). (d) The Lineweaver–Burk plot obtained by varying the concentration of TMB (100–1000 μM) with a fixed amount of H2O2 (700 mM). All experiments were carried out in 0.2 M NaOAc buffer (pH 3.5) at 40 °C, and the absorbance was measured at 652 nm. The error bars depict the standard error obtained from three replicates of the measurements.
Figure 5
Figure 5. Detection of Hcy using AuNP-pSi shown through (a) digital photographs showing a change in the color intensity upon addition of different concentrations of Hcy (1–750 μM) to AuNP-pSi. The drastic reduction in appearance of the bluish-green color indicates the attachment of thiols to Au in nanohybrids that impedes the TMB oxidation reaction. (b) Corresponding reduction in absorbance (at 652 nm) in percentage in relation to the control (AuNP-pSi without Hcy). A greater reduction in absorbance at 652 nm is observed with increasing concentration of Hcy, confirming the visual results from the digital photographs. (c) Detection of Hcy in human serum is shown through reduction in absorbance (at 652 nm) relative to the control (AuNP-pSi without Hcy) for two different concentrations (100 and 250 μM) of Hcy. The Hcy detection performance of AuNP-pSi in human serum was comparable to their detection ability in NaOAc buffer. (d) Selectivity analysis of the AuNP-pSi nanozyme: homocysteine (Hcy), alanine (A), phenylalanine (F), leucine (L), lysine (K), glycine (G), and l-aspartic acid (D). The concentration of each amino acid was100 μM. The results are presented as reduction in absorbance in percentage in relation to the control (AuNP-pSi). All experiments were carried out in NaOAc buffer (pH 3.5) reaction mixtures containing 700 mM H2O2 and 1000 μM TMB, except for experiments involving real samples carried out in human serum. Error bars represent the standard deviation from three independent experiments.
References
This article references 70 other publications.
- 1Lu, M.; Wang, C.; Ding, Y.; Peng, M.; Zhang, W.; Li, K.; Wei, W.; Lin, Y. Fe–N/C single-atom catalysts exhibiting multienzyme activity and ROS scavenging ability in cells. Chem. Commun. 2019, 55 (96), 14534– 14537, DOI: 10.1039/C9CC07408B1https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitFegsLnN&md5=194d8c18b204aa78808a254e7f09dc99Fe-N/C single-atom catalysts exhibiting multienzyme activity and ROS scavenging ability in cellsLu, Mingju; Wang, Chao; Ding, Yongqi; Peng, Meihong; Zhang, Wang; Li, Kai; Wei, Wei; Lin, YuqingChemical Communications (Cambridge, United Kingdom) (2019), 55 (96), 14534-14537CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)Fe-N/C single atom catalysts (SACs) exhibit peroxidase-like, oxidase-like, catalase-like, and glutathione peroxidase-like activity. Fe-N/C SACs are successfully applied to control the intracellular H2O2 level. This study not only explores the types of SACs mimicking enzymes but also provides opportunities for SACs in biomedical and other bioengineering applications.
- 2Wolfe, M. G.; Ali, M. M.; Brennan, J. D. Enzymatic litmus test for selective colorimetric detection of C–C single nucleotide polymorphisms. Anal. Chem. 2019, 91 (7), 4735– 4740, DOI: 10.1021/acs.analchem.9b002352https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXkslentrw%253D&md5=170de6f8aac56066e74ca06236b63b73Enzymatic litmus test for selective colorimetric detection of C-C single nucleotide polymorphismsWolfe, Michael G.; Ali, M. Monsur; Brennan, John D.Analytical Chemistry (Washington, DC, United States) (2019), 91 (7), 4735-4740CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)A paper based litmus test has been developed using modulation of urease enzyme activity for detection of C-C mismatch single nucleotide polymorphisms (SNPs) by the naked eye. Urease is first inactivated with silver ions and printed onto paper microzones. Addn. of DNA contg. C-C mismatches reactivates urease via binding of Ag(I), allowing restoration of urease activity, hydrolysis of urea to produce ammonia, and an increase in pH, which is monitored colorimetrically using a pH indicator with a limit of detection of 11 nM DNA in 40 min. The assay system is easy to use, portable, and stable for at least 30 days at ambient temp. To assess the versatility and practical application of the paper sensor, we used it to identify a G > C transversion present in human genomic DNA from a ductal carcinoma cell line, a mutation commonly found in breast cancer. We believe this new assay system has the potential to be a low-cost method for rapidly identifying DNA with the C-C mismatch SNP as a means of cancer screening in resource-limited areas.
- 3Whitesides, G. M.; Wong, C. H. Enzymes as catalysts in synthetic organic chemistry [new synthetic methods (53)]. Angew. Chem., Int. Ed. 1985, 24 (8), 617– 638, DOI: 10.1002/anie.198506173There is no corresponding record for this reference.
- 4Apetrei, I.; Rodriguez-Mendez, M.; Apetrei, C.; De Saja, J. Enzyme sensor based on carbon nanotubes/cobalt (II) phthalocyanine and tyrosinase used in pharmaceutical analysis. Sens. Actuators, B 2013, 177, 138– 144, DOI: 10.1016/j.snb.2012.10.1314https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsFKrs78%253D&md5=0434e56a1841668edc8a8048ba888e0eEnzyme sensor based on carbon nanotubes/cobalt(II) phthalocyanine and tyrosinase used in pharmaceutical analysisApetrei, I. M.; Rodriguez-Mendez, M. L.; Apetrei, C.; de Saja, J. A.Sensors and Actuators, B: Chemical (2013), 177 (), 138-144CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A multicomponent enzyme sensor was used to evaluate phenolic compds. in plant-based pharmaceutical formulations. Multiwall carbon nanotubes were used as carbonaceous material used for the electrode construction. Cobalt phthalocyanine was used as electron mediator and tyrosinase as biocatalyst. The enzyme sensor performance was analyzed by cyclic voltammetry and amperometry in model soln. of catechol and catechin. The cyclic voltammograms and the amperometric curves show an intense cathodic peak depending on the concn. of thephenolic compd. The cathodic peak was attributed to the redn. of enzymically produced o-quinone at the enzyme sensor surface. For the model phenolics analyzed, the kinetics of the enzymic reaction fitted into a Michaelis-Menten type kinetics, as confirmed by the h parameter close to 1 obtained from the Hill's plot. The detection limits were in the range of 1.66-6.32 μM demonstrating good quality performances of the enzyme sensor. Pharmaceutical samples were analyzed with multi-component biocomposite enzyme sensor to evaluate its real feasibility in pharmaceutical anal.
- 5Zhang, X.; Li, G.; Wu, D.; Li, X.; Hu, N.; Chen, J.; Chen, G.; Wu, Y. Recent progress in the design fabrication of metal-organic frameworks-based nanozymes and their applications to sensing and cancer therapy. Biosens. Bioelectron. 2019, 137, 178– 198, DOI: 10.1016/j.bios.2019.04.0615https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXps1Whur0%253D&md5=c096587e6946e163079dd994b28ec08fRecent progress in the design fabrication of metal-organic frameworks-based nanozymes and their applications to sensing and cancer therapyZhang, Xianlong; Li, Guoliang; Wu, Di; Li, Xiuling; Hu, Na; Chen, Jian; Chen, Guang; Wu, YongningBiosensors & Bioelectronics (2019), 137 (), 178-198CODEN: BBIOE4; ISSN:0956-5663. (Elsevier B.V.)The nanomaterials with enzyme-like catalytic activity, named as nanozymes, have aroused wide research interest owing to their striking merits. Metal-org. frameworks (MOFs) have showed great prospect in the construction of novel nanozymes. In this review, firstly, we summarize the most recent contributions in the design construction of the MOFs-based nanozymes. Then, we conc. our attention on their applications in the fields of sensing and cancer therapies. According to the design strategies, we categorized MOFs-based nanozymes into four classes for review (i.e. pristine MOFs, MOFs with modification, MOFs-based nanocomposites, and MOF derivs.). Meanwhile, the emerging and fascinating 2D MOFs-based nanozymes were also reviewed. A variety of novel applications are also discussed, including nanozymes catalytic mediated signal amplification in sensing applications (e.g. colorimetric sensing, fluorescent sensing, chemiluminescent sensing, electrochem. sensing, and surface-enhanced Raman scattering (SERS)), and nanozymes catalytic mediated cancer therapy (i.e. cancer-starvation therapy, enhancing photodynamic therapy, and cancer-starvation and PDT synergistic therapy). At the end of the article, future opportunities and challenges in this promising research area are tentatively proposed.
- 6Lin, Y.; Ren, J.; Qu, X. Catalytically active nanomaterials: a promising candidate for artificial enzymes. Acc. Chem. Res. 2014, 47 (4), 1097– 1105, DOI: 10.1021/ar400250z6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXpt1Krsw%253D%253D&md5=a48acb7b9c00806fb7ec2b689bb207f7Catalytically active nanomaterials: A promising candidate for artificial enzymesLin, Youhui; Ren, Jinsong; Qu, XiaogangAccounts of Chemical Research (2014), 47 (4), 1097-1105CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)A review. Natural enzymes, exquisite biocatalysts mediating every biol. process in living organisms, are able to accelerate the rate of chem. reactions up to 1019-fold for specific substrates and reactions. However, the practical application of enzymes is often hampered by their intrinsic drawbacks, such as low operational stability, sensitivity of catalytic activity to environmental conditions, and high costs in prepn. and purifn. Therefore, the discovery and development of artificial enzymes is highly desired. Recently, the merging of nanotechnol. with biol. has ignited extensive research efforts for designing functional nanomaterials that exhibit various properties intrinsic to enzymes. As a promising candidate for artificial enzymes, catalytically active nanomaterials (nanozymes) show several advantages over natural enzymes, such as controlled synthesis in low cost, tunability in catalytic activities, as well as high stability against stringent conditions. Here, the authors focus on their recent progress in exploring and constructing such nanoparticulate artificial enzymes, including graphene oxide, graphene-hemin nanocomposites, carbon nanotubes, carbon nanodots, mesoporous silica-encapsulated gold nanoparticles, gold nanoclusters, and nanoceria. According to their structural characteristics, these enzyme mimics have been categorized into 3 classes: carbon-based, metal-based, and metal-oxide-based nanomaterials. The authors highlight the important role of catalytic nanomaterials in the fields of biomimetics. First, the authors provide a practical introduction to the identification of these nanozymes, the source of the enzyme-like activities, and the enhancement of activities via rational design and engineering. Then, the authors briefly describe new or enhanced applications of certain nanozymes in biomedical diagnosis, environmental monitoring, and therapeutics. For instance, the authors have successfully used these biomimetic catalysts as colorimetric probes for the detection of cancer cells, nucleic acids, proteins, metal ions, and other small mols. In addn., the authors also introduce 3 exciting advances in the use of efficient modulators on artificial enzyme systems to improve the catalytic performance of existing nanozymes. For example, the authors report that graphene oxide could serve as a modulator to greatly improve the catalytic activity of lysozyme-stabilized gold nanoclusters at neutral pH, which will have great potential for applications in biol. systems. The authors show that, through the incorporation of modulators into artificial enzymes, they can offer a facile but highly effective way to improve their overall catalytic performance or realize catalytic reactions that were not possible in the past. The authors expect that nanozymes with unique properties and functions will attract increasing research interest and lead to new opportunities in various fields of research.
- 7Gao, L.; Zhuang, J.; Nie, L.; Zhang, J.; Zhang, Y.; Gu, N.; Wang, T.; Feng, J.; Yang, D.; Perrett, S.; Yan, X. Intrinsic peroxidase-like activity of ferromagnetic nanoparticles. Nat. Nanotechnol. 2007, 2 (9), 577– 583, DOI: 10.1038/nnano.2007.2607https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpvVOksLg%253D&md5=c314011a4e43e9bddf51babae3e2df47Intrinsic peroxidase-like activity of ferromagnetic nanoparticlesGao, Lizeng; Zhuang, Jie; Nie, Leng; Zhang, Jinbin; Zhang, Yu; Gu, Ning; Wang, Taihong; Feng, Jing; Yang, Dongling; Perrett, Sarah; Yan, XiyunNature Nanotechnology (2007), 2 (9), 577-583CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)Nanoparticles contg. magnetic materials, such as magnetite (Fe3O4), are particularly useful for imaging and sepn. techniques. As these nanoparticles are generally considered to be biol. and chem. inert, they are typically coated with metal catalysts, antibodies or enzymes to increase their functionality as sepn. agents. Here, we report that magnetite nanoparticles in fact possess an intrinsic enzyme mimetic activity similar to that found in natural peroxidases, which are widely used to oxidize org. substrates in the treatment of wastewater or as detection tools. Based on this finding, we have developed a novel immunoassay in which antibody-modified magnetite nanoparticles provide three functions: capture, sepn. and detection. The stability, ease of prodn. and versatility of these nanoparticles makes them a powerful tool for a wide range of potential applications in medicine, biotechnol. and environmental chem.
- 8Cormode, D. P.; Gao, L.; Koo, H. Emerging biomedical applications of enzyme-like catalytic nanomaterials. Trends Biotechnol. 2018, 36 (1), 15– 29, DOI: 10.1016/j.tibtech.2017.09.0068https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhs1CmsL%252FL&md5=d1598eed24ff110e2f14513fd0738eb7Emerging Biomedical Applications of Enzyme-Like Catalytic NanomaterialsCormode, David P.; Gao, Lizeng; Koo, HyunTrends in Biotechnology (2018), 36 (1), 15-29CODEN: TRBIDM; ISSN:0167-7799. (Elsevier Ltd.)A review. Nanomaterials have been developed for many biomedical applications, including medical imaging, drug delivery, and antimicrobial coatings. Intriguingly, nanoparticles can display 'enzyme-like' activity and have been explored as alternatives to natural enzymes in several industrial and energy-related applications. Recently, these catalytic nanomaterials with enzyme-mimetic properties have found new biomedical applications, from biofilm disruption to protection against neurodegeneration and tumor prevention. In this review we focus on recent in vivo studies demonstrating potential therapeutic uses of catalytic nanomaterials. We also provide insights about the relationships between catalytic activity, therapeutic efficacy, and biocompatibility that are crit. for clin. translatability. Finally, we discuss current challenges and future directions for the use of these nanomaterials as novel platforms for the development of sustainable, affordable, and safe therapeutics.
- 9Liu, Q.; Zhang, A.; Wang, R.; Zhang, Q.; Cui, D. A review on metal-and metal oxide-based nanozymes: properties, mechanisms, and applications. Nano–Micro Lett. 2021, 13, 154, DOI: 10.1007/s40820-021-00674-89https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXitFGmu7bK&md5=b6d8f6bb70dbfa231b2bda8b397a948fA review on metal- and metal oxide-based nanozymes: properties, mechanisms, and applicationsLiu, Qianwen; Zhang, Amin; Wang, Ruhao; Zhang, Qian; Cui, DaxiangNano-Micro Letters (2021), 13 (), 154CODEN: NLAEBV; ISSN:2150-5551. (Nano-Micro Letters)A review. Since the ferromagnetic (Fe3O4) nanoparticles were firstly reported to exert enzyme-like activity in 2007, extensive research progress in nanozymes has been made with deep investigation of diverse nanozymes and rapid development of related nanotechnologies. As promising alternatives for natural enzymes, nanozymes have broadened the way toward clin. medicine, food safety, environmental monitoring, and chem. prodn. The past decade has witnessed the rapid development of metal- and metal oxide-based nanozymes owing to their remarkable physicochem. properties in parallel with low cost, high stability, and easy storage. It is widely known that the deep study of catalytic activities and mechanism sheds significant influence on the applications of nanozymes. This review digs into the characteristics and intrinsic properties of metal- and metal oxide-based nanozymes, esp. emphasizing their catalytic mechanism and recent applications in biol. anal., relieving inflammation, antibacterial, and cancer therapy. We also conclude the present challenges and provide insights into the future research of nanozymes constituted of metal and metal oxide nanomaterials.
- 10Masud, M. K.; Na, J.; Younus, M.; Hossain, M. S. A.; Bando, Y.; Shiddiky, M. J.; Yamauchi, Y. Superparamagnetic nanoarchitectures for disease-specific biomarker detection. Chem. Soc. Rev. 2019, 48 (24), 5717– 5751, DOI: 10.1039/C9CS00174C10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitFCjtb7M&md5=8f9023ce9c12920db1320815abd2ce5aSuperparamagnetic nanoarchitectures for disease-specific biomarker detectionMasud, Mostafa Kamal; Na, Jongbeom; Younus, Muhammad; Hossain, Md. Shahriar A.; Bando, Yoshio; Shiddiky, Muhammad J. A.; Yamauchi, YusukeChemical Society Reviews (2019), 48 (24), 5717-5751CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)A review. The detection of clin. relevant disease-specific biomols., including nucleic acids, circulating tumor cells, proteins, antibodies, and extracellular vesicles, has been indispensable to understand their functions in disease diagnosis and prognosis. Therefore, a biosensor for the robust, ultrasensitive, and selective detection of these low-abundant biomols. in body fluids (blood, urine, and saliva) is emerging in current clin. research. In recent years, nanomaterials, esp. superparamagnetic nanomaterials, have played essential roles in biosensing due to their intrinsic magnetic, electrochem., and optical properties. However, engineered multicomponent magnetic nanoparticle-based current biosensors that offer the advantages of excellent stability in a complex biomatrix; easy and alterable biorecognition of ligands, antibodies, and receptor mols.; and unified point-of-care integration have yet to be achieved. This review introduces the recent advances in superparamagnetic nanostructures for electrochem. and optical biosensing for disease-specific biomarkers. This review emphasizes the synthesis, biofunctionalization, and intrinsic properties of nanomaterials essential for robust, ultrasensitive biosensing. With a particular emphasis on nanostructure-based electrochem. and optical detection of disease-specific biomarkers such as nucleic acids (DNA and RNA), proteins, autoantibodies, and cells, this review also chronicles the needs and challenges of nanoarchitecture-based detection. These summaries provide further insights for researchers to inspire their future work on the development of nanostructures for integrating into biosensing and devices for a broad field of applications in anal. sensing and in clinic.
- 11Lou-Franco, J.; Das, B.; Elliott, C.; Cao, C. Gold nanozymes: from concept to biomedical applications. Nano–Micro Lett. 2021, 13, 10, DOI: 10.1007/s40820-020-00532-zThere is no corresponding record for this reference.
- 12Hou, Q.; Zhang, X.; Lin, M.; Dai, Y.; Xia, F. Organic monolayer on gold nanoparticles as hydrolytic nanozymes. Giant 2022, 12, 100122 DOI: 10.1016/j.giant.2022.10012212https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XivVCqsL7K&md5=5f65bd89c2182ad801d6094298315a4eOrganic monolayer on gold nanoparticles as hydrolytic nanozymesHou, Qin; Zhang, Xiaojin; Lin, Meihua; Dai, Yu; Xia, FanGiant (2022), 12 (), 100122CODEN: GIANAR; ISSN:2666-5425. (Elsevier Ltd.)Nanozymes are a class of nanomaterials with enzyme-like catalytic properties, which have environmental tolerance and long-term stability. Improving catalytic activity and expanding the variety of nanozymes are the prerequisites to complement or even replace natural enzymes. The assembly of org. monolayer contg. catalytic site on the surface of inorg. nanoparticles is a very effective strategy to improve catalytic activity and expand the variety of nanozymes. Here, we discuss how to construct org. monolayer on the surface of gold nanoparticles, classify the types of org. monolayer, and introduce their applications in nucleic acid hydrolysis and sensing. It is hoped to further promote the research progress of hydrolytic nanozymes.
- 13Wu, J.; Li, S.; Wei, H. Integrated nanozymes: facile preparation and biomedical applications. Chem. Commun. 2018, 54 (50), 6520– 6530, DOI: 10.1039/C8CC01202D13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXksFaru7k%253D&md5=b0d42ce465bcdb811c478d571885e90aIntegrated nanozymes: facile preparation and biomedical applicationsWu, Jiangjiexing; Li, Sirong; Wei, HuiChemical Communications (Cambridge, United Kingdom) (2018), 54 (50), 6520-6530CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)A review. Nanozymes have been viewed as the next generation of artificial enzymes due to their low cost, large sp. surface area, and good robustness under extreme conditions. However, the moderate activity and limited selectivity of nanozymes have impeded their usage. To overcome these shortcomings, integrated nanozymes (INAzymes) have been developed by encapsulating two or more different biocatalysts (e.g., natural oxidases and peroxidase mimics) together within confined frameworks. On the one hand, with the assistance of natural enzymes, INAzymes are capable of specifically recognizing targets. On the other hand, nanoscale confinement brought about by integration significantly enhances the cascade reaction efficiency. In this Feature Article, we highlight the newly developed INAzymes, covering from synthetic strategies to versatile applications in biodetection and therapeutics. Moreover, it is predicted that INAzymes with superior activities, specificity, and stability will enrich the research of nanozymes and pave new ways in designing multifunctional nanozymes.
- 14Zhang, R.; Fan, K.; Yan, X. Nanozymes: created by learning from nature. Sci. China Life Sci. 2020, 63 (8), 1183– 1200, DOI: 10.1007/s11427-019-1570-714https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB38%252FjvVajsA%253D%253D&md5=4d094c61c72ed1da761ceae728519535Nanozymes: created by learning from natureZhang Ruofei; Fan Kelong; Yan Xiyun; Fan Kelong; Yan XiyunScience China. Life sciences (2020), 63 (8), 1183-1200 ISSN:.Nanozymes, a type of nanomaterials with enzyme-like activity, have shown great potential to replace natural enzymes in many fields such as biochemical detection, environmental management and disease treatment. However, the catalytic efficiency and substrate specificity of nanozymes still need improvement. To further optimize the enzymatic properties of nanozymes, recent studies have introduced the structural characteristics of natural enzymes into the rational design of nanozymes, either by employing small molecules to mimic the cofactors of natural enzymes to boost nanozymes' catalytic potential, or by simulating the active center of natural enzymes to construct the nanostructure of nanozymes. This review introduces the commonly used bio-inspired strategies to create nanozymes, aiming at clarifying the current progress and bottlenecks. Advances and challenges focusing on the research of bio-inspired nanozymes are outlined to provide ideas for the de novo design of ideal nanozymes.
- 15Golchin, K.; Golchin, J.; Ghaderi, S.; Alidadiani, N.; Eslamkhah, S.; Eslamkhah, M.; Davaran, S.; Akbarzadeh, A. Gold nanoparticles applications: from artificial enzyme till drug delivery. Artif. Cells Nanomed. Biotechnol. 2018, 46 (2), 250– 254, DOI: 10.1080/21691401.2017.130539315https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXnvVCrurw%253D&md5=9f31de7f4da4a8da58c1e9951f09c299Gold nanoparticles applications: from artificial enzyme till drug deliveryGolchin, Kazem; Golchin, Jafar; Ghaderi, Shahrooz; Alidadiani, Neda; Eslamkhah, Sajjad; Eslamkhah, Masoud; Davaran, Soodabeh; Akbarzadeh, AbolfazlArtificial Cells, Nanomedicine, and Biotechnology (2018), 46 (2), 250-254CODEN: ACNBCI; ISSN:2169-141X. (Taylor & Francis Ltd.)A review. Today, nano-medicine promotes new therapeutics and diagnostics tools, including sensing of biomols. as a biosensor, cancer chemotherapy and drug or gene delivery. Because of small size and biocompatibility of gold nanoparticles (GNPs), they become a good candidate for biol. application. Also, thanks to their biol. and chem. properties, they can mimic function of some enzymes including super oxide dismutase (SOD), esterase, etc. Also, biomaterials and bioengineering have grown so fast since the last decade for many therapeutic applications such as tissue regeneration. Among these cutting edge technol., nanomaterials find the way to becoming a very powerful tool for using in many fields of researchers including biosensing, gene therapy and chemotherapy. In this review, we focused on some biol. applications of GNPs in biol. and medicine.
- 16Wang, X.; Mei, Z.; Wang, Y.; Tang, L. Comparison of four methods for the biofunctionalization of gold nanorods by the introduction of sulfhydryl groups to antibodies. Beilstein J. Nanotechnol. 2017, 8 (1), 372– 380, DOI: 10.3762/bjnano.8.3916https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXpslejsLk%253D&md5=7502733f116e9df264b6ab7a8c3910a1Comparison of four methods for the biofunctionalization of gold nanorods by the introduction of sulfhydryl groups to antibodiesWang, Xuefeng; Mei, Zhong; Wang, Yanyan; Tang, LiangBeilstein Journal of Nanotechnology (2017), 8 (), 372-380CODEN: BJNEAH; ISSN:2190-4286. (Beilstein-Institut zur Foerderung der Chemischen Wissenschaften)Introducing sulfhydryl groups to biomols. to functionalize gold nanorods (GNRs) is an attractive method that involves the creation of a strong Au-S bond. Previously, we developed a facile method to functionalize GNR surfaces by thiolating antibodies using Traut's reagent. In the current study, we evaluated several methods for the introduction of thiol groups onto the surface of GNRs by using Traut's reagent, dithiotreitol (DTT), dithiolarom. PEG6-CONHNH , and thiol-polyethylene glycolamine (SHPEG-NH) combined with EDC reaction. We showed that the four above-mentioned thiolation methods can efficiently functionalize GNRs and simplify the functionalization procedures. The formed GNR-bioconjugates showed superior stability without compromising the biol. activity. The GNR nanochip prepd. with these four thiolated antibodies can detect human IgG targets with specificity. However, SH-PEG-NH combined with EDC reaction may affect the amt. of functionalized GNRs because of the efficiency of thiol moiety linkage to antibodies, thereby affecting the sensitivity of the GNR sensor. The introduction of a thiol group to antibodies by using Traut's reagent, DTT, and PEG6-CONHNH allowed for direct immobilization onto the GNR surface, improved the efficacy of functionalized GNRs, and increased the sensitivity in response to target detection as a biosensor. Given that PEG6-CONHNH modification requires glycosylated biomols., Traut's reagent and DTT thiolation are recommended as universal applications of GNR biofunctionalization and can be easily extended to other sensing applications based on other gold nanostructures or new biomols.
- 17Chang, J.-Y.; Wu, H.; Chen, H.; Ling, Y.-C.; Tan, W. Oriented assembly of Au nanorods using biorecognition system. Chem. Commun. 2005, (8), 1092– 1094, DOI: 10.1039/b414059a17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhsFOktbk%253D&md5=0eca59aa6fb2af851768008fa0f669e2Oriented assembly of Au nanorods using biorecognition systemChang, Jia-Yaw; Wu, Huimeng; Chen, Hui; Ling, Yong-Chien; Tan, WeihongChemical Communications (Cambridge, United Kingdom) (2005), (8), 1092-1094CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)The design and formation of a linear assembly of gold nanorods using a biomol. recognition system are described. Anti-mouse IgG was immobilized on the {111} end faces of gold nanorods through a thioctic acid contg. a terminal carboxyl group. The biofunctionalized nanorods can be assembled with the desired length using mouse IgG for biorecognition and binding. The gold nanorods can be assembled to extended nanorod chains, which can be as long as 3 μm. These assembled nanostructures may be used as the precursors for future nanodevices.
- 18Turkevich, J.; Stevenson, P. C.; Hillier, J. A study of the nucleation and growth processes in the synthesis of colloidal gold. Discuss. Faraday Soc. 1951, 11, 55– 75, DOI: 10.1039/df9511100055There is no corresponding record for this reference.
- 19BarathManiKanth, S.; Kalishwaralal, K.; Sriram, M.; Pandian, S. R. K.; Youn, H.-s.; Eom, S.; Gurunathan, S. Anti-oxidant effect of gold nanoparticles restrains hyperglycemic conditions in diabetic mice. J. Nanobiotechnol. 2010, 8 (1), 16, DOI: 10.1186/1477-3155-8-1619https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC3cjit1yrug%253D%253D&md5=44597ea21df720db7092b7bc7c8797b2Anti-oxidant effect of gold nanoparticles restrains hyperglycemic conditions in diabetic miceBarathmanikanth Selvaraj; Kalishwaralal Kalimuthu; Sriram Muthuirulappan; Pandian Sureshbabu Ram Kumar; Youn Hyung-Seop; Eom Soohyun; Gurunathan SangiliyandiJournal of nanobiotechnology (2010), 8 (), 16 ISSN:.BACKGROUND: Oxidative stress is imperative for its morbidity towards diabetic complications, where abnormal metabolic milieu as a result of hyperglycemia, leads to the onset of several complications. A biological antioxidant capable of inhibiting oxidative stress mediated diabetic progressions; during hyperglycemia is still the need of the era. The current study was performed to study the effect of biologically synthesized gold nanoparticles (AuNPs) to control the hyperglycemic conditions in streptozotocin induced diabetic mice. RESULTS: The profound control of AuNPs over the anti oxidant enzymes such as GSH, SOD, Catalase and GPx in diabetic mice to normal, by inhibition of lipid peroxidation and ROS generation during hyperglycemia evidence their anti-oxidant effect during hyperglycemia. The AuNPs exhibited an insistent control over the blood glucose level, lipids and serum biochemical profiles in diabetic mice near to the control mice provokes their effective role in controlling and increasing the organ functions for better utilization of blood glucose. Histopathological and hematological studies revealed the non-toxic and protective effect of the gold nanoparticles over the vital organs when administered at dosage of 2.5 mg/kilogram.body.weight/day. ICP-MS analysis revealed the biodistribution of gold nanoparticles in the vital organs showing accumulation of AuNPs in the spleen comparatively greater than other organs. CONCLUSION: The results obtained disclose the effectual role of AuNPs as an anti-oxidative agent, by inhibiting the formation of ROS, scavenging free radicals; thus increasing the anti-oxidant defense enzymes and creating a sustained control over hyperglycemic conditions which consequently evoke the potential of AuNPs as an economic therapeutic remedy in diabetic treatments and its complications.
- 20He, S.; Chua, J.; Tan, E. K. M.; Kah, J. C. Y. Optimizing the SERS enhancement of a facile gold nanostar immobilized paper-based SERS substrate. RSC Adv. 2017, 7 (27), 16264– 16272, DOI: 10.1039/C6RA28450G20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXktFyrtr8%253D&md5=b7e82415da36f996c721d2dfa5f07d56Optimizing the SERS enhancement of a facile gold nanostar immobilized paper-based SERS substrateHe, Shuai; Chua, Jefri; Tan, Eddie Khay Ming; Kah, James Chen YongRSC Advances (2017), 7 (27), 16264-16272CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)While surface-enhanced Raman scattering (SERS) is a useful technique for the rapid and sensitive detection of biochem. compds., conventional SERS chips suffer from high cost, complicated fabrication, inefficient sample collection processes and being not biocompatible. Here, we developed a facile, low-cost and highly sensitive gold nanostar (AuNS) immobilized paper-based SERS substrate that can be easily prepd. in any lab. We performed studies on the paper materials, immobilization strategies, and SERS acquisition conditions to optimize the SERS enhancement and demonstrated that an optimized SERS signal was obtained from a dry substrate and wet analyte configuration suitable for rapid point-of-care detection. Using crystal violet (CV) as the Raman probe mol., the optimized SERS substrate was prepd. by having multiple drops of ∼100 pM of sodium citrate-treated colloidal AuNS on common lab. filter paper before acquiring SERS spectra of CV freshly dripped onto the pre-dried AuNS-filter paper substrate. The optimized AuNS-filter paper substrate exhibited a SERS enhancement factor higher than that of two com. Au/Ag-based SERS chips, with a detection limit of 1 nM CV and a SERS enhancement factor of up to 1.2 × 107. Such an optimized dry substrate and wet analyte configuration meant that the paper-based SERS substrate could be stored before use and Raman acquisition could be performed immediately without the need for the sample to dry. This makes the AuNS-filter paper substrate a simple and low-cost tool for trace level detection of biochem. species in a rapid, sensitive and non-destructive manner.
- 21Ivanov, M. R.; Bednar, H. R.; Haes, A. J. Investigations of the mechanism of gold nanoparticle stability and surface functionalization in capillary electrophoresis. ACS Nano 2009, 3 (2), 386– 394, DOI: 10.1021/nn800561921https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXmtFGqtw%253D%253D&md5=a9d97ee5bfcadb378982d41ddb6b0f58Investigations of the Mechanism of Gold Nanoparticle Stability and Surface Functionalization in Capillary ElectrophoresisIvanov, Michael R.; Bednar, Heidi R.; Haes, Amanda J.ACS Nano (2009), 3 (2), 386-394CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Covalently functionalized gold nanoparticles influence capillary electrophoresis sepns. of neurotransmitters in a concn.- and surface-chem.-dependent manner. Gold nanoparticles with either primarily covalently functionalized carboxylic acid (Au@COOH) or amine (Au@NH2) surface groups are characterized using extinction spectroscopy, transmission electron microscopy, and zeta potential measurements. The impact of the presence of nanoparticles and their surface chem. is investigated, and at least three nanoparticle-specific mechanisms are found to effect sepns. First, the degree of nanoparticle-nanoparticle interactions is quantified using a new parameter termed the crit. nanoparticle concn. (CNC). CNC is defined as the lowest concn. of nanoparticles that induces predominant nanoparticle aggregation under specific buffer conditions and is detd. using dual-wavelength photodiode array detection. Once the CNC has been exceeded, reproducible sepns. are no longer obsd. Second, nanoparticle-analyte interactions are dictated by electrostatic interactions which depend on the pKa of the analyte and surface charge of the nanoparticle. Finally, nanoparticle-capillary interactions occur in a surface-chem.-dependent manner. Run buffer viscosity is influenced by the formation of a nanoparticle steady-state pseudostationary phase along the capillary wall. Despite differences in buffer viscosity leading to changes in neurotransmitter mobilities, no significant changes in electroosmotic flow were obsd. As a result of these three nanoparticle-specific interactions, Au@NH2 nanoparticles increase the mobility of the neurotransmitters while a smaller opposite effect is obsd. for Au@COOH nanoparticles. Understanding nanoparticle behavior in the presence of an elec. field will have significant impacts in sepn. science where nanoparticles can serve to improve either the mobility or detection sensitivity of target mols.
- 22Liu, W.; Tian, L.; Du, J.; Wu, J.; Liu, Y.; Wu, G.; Lu, X. Triggered peroxidase-like activity of Au decorated carbon dots for colorimetric monitoring of Hg2+ enrichment in Chlorella vulgaris. Analyst 2020, 145 (16), 5500– 5507, DOI: 10.1039/D0AN00930J22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtFCnu7bK&md5=f49b4f4075704f009c1b95f64033798cTriggered peroxidase-like activity of Au decorated carbon dots for colorimetric monitoring of Hg2+ enrichment in Chlorella vulgarisLiu, Wene; Tian, Lili; Du, Jie; Wu, Jiangmin; Liu, Yongmei; Wu, Guofan; Lu, XiaoquanAnalyst (Cambridge, United Kingdom) (2020), 145 (16), 5500-5507CODEN: ANALAO; ISSN:0003-2654. (Royal Society of Chemistry)Developing a rapid, low-cost, and multimode detection method for heavy metal ions remains a compelling goal for many applications, including food safety, environmental and biol. anal. This study investigated the influence of Hg2+ on the peroxidase-like activity of gold nanoparticles (GNPs) decorated on carbon dots (CDs) from lysine (denoted as GNP@CDs). A new type of Hg2+-triggered peroxidase-like activity of GNP@CDs was discovered, which could catalyze the oxidn. of the colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue TMB. Based on the regulation of the catalytically triggered activity, a sensitive colorimetric method for the detection of Hg2+ was developed, with a linear range of 7-150 nM, providing a limit of detection as low as 3.7 nM. The sensor is simple and rapid, and was successfully applied to the detection of Hg2+ enrichment in chlorella, suggesting a promising application in biol. anal.
- 23Ko, E.; Tran, V.-K.; Son, S. E.; Hur, W.; Choi, H.; Seong, G. H. Characterization of Au@PtNP/GO nanozyme and its application to electrochemical microfluidic devices for quantification of hydrogen peroxide. Sens. Actuators, B 2019, 294, 166– 176, DOI: 10.1016/j.snb.2019.05.05123https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtVekur3F&md5=83f0347982a4875e7b3b30cd334ba6b3Characterization of Au@PtNP/GO nanozyme and its application to electrochemical microfluidic devices for quantification of hydrogen peroxideKo, Euna; Tran, Van-Khue; Son, Seong Eun; Hur, Won; Choi, Hyun; Seong, Gi HunSensors and Actuators, B: Chemical (2019), 294 (), 166-176CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Nanostructured artificial enzymes, known as nanozymes, have been considered effective alternatives for natural enzymes with the attractive advantages. Herein, bimetallic Au and Pt nanoparticles with graphene oxide (GO) were immobilized chem. on the surface of agarose microbeads. Due to the synergistic effect of the bimetallic nanoparticles and GO (Au@PtNP/GO), this hybrid nanostructure exhibited strong peroxidase-like catalytic activity toward 3,3',5,5'-tetramethylbenzidine (TMB) substrate in the presence of H2O2. Colorimetric detn. of H2O2, indicated by the blue color of the oxidized TMB within 1 min, was obsd. using the Au@PtNP/GO nanozymes. To demonstrate practical application of the nanozymes, the Au@PtNP/GO microbeads were packed into a film-based electrochem. point-of-care (POC) device for sensitive and rapid H2O2 detection. Upon introduction of TMB substrate soln. contg. H2O2, the catalytically oxidized TMB was electrochem. reduced on the electrode surfaces, resulting in a broader detection range of H2O2 (1 μM - 3 mM) and a lower LOD (1.62 μM) than achievable with the colorimetric detection method. Moreover, the developed POC devices showed the capability of accurate detn. of H2O2 with strong repeatability and reproducibility in real sample test using artificial urine.
- 24Poulos, T. L. Heme enzyme structure and function. Chem. Rev. 2014, 114 (7), 3919– 3962, DOI: 10.1021/cr400415k24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXkvFGgsg%253D%253D&md5=e7857cca01883857d47254628ed69918Heme Enzyme Structure and FunctionPoulos, Thomas L.Chemical Reviews (Washington, DC, United States) (2014), 114 (7), 3919-3962CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Metalloporphyrins are employed in various capacities throughout the biosphere, and of these, heme (iron protoporphyrin IX) is one of the most abundant and widely used. Heme is well-known for its roles in shuttling electrons between proteins as seen in mitochondrial respiration and in O2 storage as is the case with globins, but it also serves as a cofactor in multiple enzyme-mediated processes. Although heme enzymes can catalyze both reductive and oxidative reactions, the present review focuses primarily on those that catalyze oxidn. reactions, and esp. those for which crystal structures are available.
- 25Guéant, J.-L.; Caillerez-Fofou, M.; Battaglia-Hsu, S.; Alberto, J.-M.; Freund, J.-N.; Dulluc, I.; Adjalla, C.; Maury, F.; Merle, C.; Nicolas, J.-P. Molecular and cellular effects of vitamin B12 in brain, myocardium and liver through its role as co-factor of methionine synthase. Biochimie 2013, 95 (5), 1033– 1040, DOI: 10.1016/j.biochi.2013.01.02025https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjt1Wqtr4%253D&md5=8ba214c24735ae3a9d22cc05ddc586b9Molecular and cellular effects of vitamin B12 in brain, myocardium and liver through its role as co-factor of methionine synthaseGueant, Jean-Louis; Caillerez-Fofou, Maatem; Battaglia-Hsu, Shyuefang; Alberto, Jean-Marc; Freund, Jean-Noel; Dulluc, Isabelle; Adjalla, Charles; Maury, Florence; Merle, Carole; Nicolas, Jean-Pierre; Namour, Fares; Daval, Jean-LucBiochimie (2013), 95 (5), 1033-1040CODEN: BICMBE; ISSN:0300-9084. (Elsevier Masson SAS)A review. Vitamin B12 (cobalamin, cbl) is a cofactor of methionine synthase (MTR) in the synthesis of methionine, the precursor of the universal Me donor S-Adenosylmethionine (SAM), which is involved in epigenomic regulatory mechanisms. We have established a neuronal cell model with stable expression of a transcobalamin-oleosin chimer and subsequent decreased cellular availability of vitamin B12, which produces reduced proliferation, increased apoptosis and accelerated differentiation through PP2A, NGF and TACE pathways. Anti-transcobalamin antibody or impaired transcobalamin receptor expression produce also impaired proliferation in other cells. Consistently, the transcription, protein expression and activity of MTR are increased in proliferating cells of skin and intestinal epitheliums, in rat intestine crypts and in proliferating CaCo2 cells, while MTR activity correlates with DNA methylation in rat intestine villi. Exposure to nitrous oxide in animal models identified impairment of MTR reaction as the most important metabolic cause of neurol. manifestations of B12 deficiency. Early vitamin B12 and folate deprivation during gestation and lactation of a dam-progeny' rat model developed in our lab. is assocd. with long-lasting disabilities of behavior and memory capacities, with persisting hallmarks related to increased apoptosis, impaired neurogenesis and altered plasticity. We found also an epigenomic deregulation of energy metab. and fatty acids beta-oxidn. in myocardium and liver, through imbalanced methylation/acetylation of PGC-1α and decreased expression of SIRT1. These nutrigenomic effects display similarities with the mol. mechanisms of fetal programming. Beside deficiency, B12 loading increases the expression of MTR through internal ribosome entry sites (IRES) and down-regulates MDR-1 gene expression. In conclusion, vitamin B12 influences cell proliferation, differentiation and apoptosis in brain. Vitamin B12 and folate combined deficiency impairs fatty acid oxidn. and energy metab. in liver and heart through epigenomic mechanisms related to imbalanced acetylation/methylation. Some but not all of these effects reflect the upstream role of vitamin B12 in SAM synthesis.
- 26Okamoto, K.; Kusano, T.; Nishino, T. Chemical nature and reaction mechanisms of the molybdenum cofactor of xanthine oxidoreductase. Curr. Pharm. Des. 2013, 19 (14), 2606– 2614, DOI: 10.2174/138161281131914001026https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXmt1ygtbg%253D&md5=a75046d0a1c789b4cad99beeffa00c9aChemical nature and reaction mechanisms of the molybdenum cofactor of xanthine oxidoreductaseOkamoto, Ken; Kusano, Teruo; Nishino, TakeshiCurrent Pharmaceutical Design (2013), 19 (14), 2606-2614CODEN: CPDEFP; ISSN:1381-6128. (Bentham Science Publishers Ltd.)A review. Xanthine oxidoreductase (XOR), a complex flavoprotein, catalyzes the metabolic reactions leading from hypoxanthine to xanthine and from xanthine to urate, and both reactions take place at the molybdenum cofactor. The enzyme is a target of drugs for therapy of gout or hyperuricemia. We review the chem. nature and reaction mechanisms of the molybdenum cofactor of XOR, focusing on molybdenum-dependent reactions of actual or potential medical importance, including nitric oxide (NO) synthesis. It is now generally accepted that XOR transfers the water-exchangeable -OH ligand of the molybdenum atom to the substrate. The hydroxyl group at OH- Mo(IV) can be replaced by urate, oxipurinol and FYX-051 derivs. and the structures of these complexes have been detd. by x-ray crystallog. under anaerobic conditions. Although formation of NO from nitrite or formation of xanthine from urate by XOR is chem. feasible, it is not yet clear whether these reactions have any physiol. significance since the reactions are catalyzed at a slow rate even under anaerobic conditions.
- 27Kumeria, T.; McInnes, S. J.; Maher, S.; Santos, A. Porous silicon for drug delivery applications and theranostics: recent advances, critical review and perspectives. Expert Opin. Drug Delivery 2017, 14 (12), 1407– 1422, DOI: 10.1080/17425247.2017.131724527https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXmtlOgsr4%253D&md5=4d83c217147c34afeb032bec5feb5f87Porous silicon for drug delivery applications and theranostics: recent advances, critical review and perspectivesKumeria, Tushar; McInnes, Steven J. P.; Maher, Shaheer; Santos, AbelExpert Opinion on Drug Delivery (2017), 14 (12), 1407-1422CODEN: EODDAW; ISSN:1742-5247. (Taylor & Francis Ltd.)A review. Porous silicon (pSi) engineered by electrochem. etching has been used as a drug delivery vehicle to address the intrinsic limitations of traditional therapeutics. Biodegradability, biocompatibility, and optoelectronic properties make pSi a unique candidate for developing biomaterials for theranostics and photodynamic therapies. This review presents an updated overview about the recent therapeutic systems based on pSi, with a crit. anal. on the problems and opportunities that this technol. faces as well as highlighting pSis growing potential. Recent progress in pSi-based research includes drug delivery systems, including biocompatibility studies, drug delivery, theranostics, and clin. trials with the most relevant examples of pSi-based systems presented here. A crit. anal. about the tech. advantages and disadvantages of these systems is provided along with an assessment on the challenges that this technol. faces, including clin. trials and investors support. PSi is an outstanding material that could improve existing drug delivery and photodynamic therapies in different areas, paving the way for developing advanced theranostic nanomedicines and incorporating payloads of therapeutics with imaging capabilities. However, more extensive in-vivo studies are needed to assess the feasibility and reliability of this technol. for clin. practice. The tech. and com. challenges that this technol. face are still uncertain.
- 28Kumeria, T.; Wang, J.; Chan, N.; Harris, T. J.; Sailor, M. J. Visual sensor for sterilization of polymer fixtures using embedded mesoporous silicon photonic crystals. ACS Sens. 2018, 3 (1), 143– 150, DOI: 10.1021/acssensors.7b0076428https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXitVSitbjF&md5=abeb38659b445c6c6b48718ae4eaf8a3Visual Sensor for Sterilization of Polymer Fixtures Using Embedded Mesoporous Silicon Photonic CrystalsKumeria, Tushar; Wang, Joanna; Chan, Nicole; Harris, Todd J.; Sailor, Michael J.ACS Sensors (2018), 3 (1), 143-150CODEN: ASCEFJ; ISSN:2379-3694. (American Chemical Society)A porous photonic crystal is integrated with a plastic medical fixture (IV connector hub) to provide a visual colorimetric sensor to indicate the presence or absence of alc. used to sterilize the fixture. The photonic crystal is prepd. in porous silicon (pSi) by electrochem. anodization of single crystal silicon, and the porosity and the stop band of the material is engineered such that the integrated device visibly changes color (green to red or blue to green) when infiltrated with alc. Two types of self-reporting devices are prepd. and their performance compared: the first type involves heat-assisted fusion of a freestanding pSi photonic crystal to the connector end of a preformed polycarbonate hub, forming a composite where the unfilled portion of the pSi film acts as the sensor; the second involves generation of an all-polymer replica of the pSi photonic crystal by complete thermal infiltration of the pSi film and subsequent chem. dissoln. of the pSi portion. Both types of sensors visibly change color when wetted with alc., and the color reverts to the original upon evapn. of the liq. The sensor performance is verified using E. coli-infected samples.
- 29Harraz, F. A.; Tsuboi, T.; Sasano, J.; Sakka, T.; Ogata, Y. Metal deposition onto a porous silicon layer by immersion plating from aqueous and nonaqueous solutions. J. Electrochem. Soc. 2002, 149 (9), C456, DOI: 10.1149/1.149884129https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XmtVCmu74%253D&md5=d06b9d05c475884ea6c7009c4edaaf21Metal Deposition onto a Porous Silicon Layer by Immersion Plating from Aqueous and Nonaqueous SolutionsHarraz, F. A.; Tsuboi, T.; Sasano, J.; Sakka, T.; Ogata, Y. H.Journal of the Electrochemical Society (2002), 149 (9), C456-C463CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)Immersion plating of metals (Ag, Cu, Ni) onto a porous Si (PS) layer from aq. and nonaq. solns. was studied. The modified PS layers after the immersion plating were analyzed by x-ray diffraction and XPS. FTIR spectroscopy and SEM were also performed to study the structural changes and microstructure of PS samples after the plating process. In both solns., the deposition of metal oxidizes PS simultaneously to SiO2. The different deposition behaviors are discussed in terms of different rest potentials of PS in these solns. and electrode potential of each metal. Immersion plating in nonaq. org. solns. shows that a trace of residual H2O affects the metal deposition. Based on the results obtained, the mechanism of metal deposition is proposed. The metal deposition proceeds by nucleation and growth via the local cell mechanism. Also metal deposition proceeds very differently on Si wafer and PS surfaces. The different deposition behaviors on both surfaces are discussed.
- 30Andsager, D.; Hilliard, J.; Nayfeh, M. Behavior of porous silicon emission spectra during quenching by immersion in metal ion solutions. Appl. Phys. Lett. 1994, 64 (9), 1141– 1143, DOI: 10.1063/1.11083230https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXivVenur8%253D&md5=61cd0c2a0df6c6bf6bbd34917f1133afBehavior of porous silicon emission spectra during quenching by immersion in metal ion solutionsAndsager, D.; Hilliard, J.; Nayfeh, M. H.Applied Physics Letters (1994), 64 (9), 1141-3CODEN: APPLAB; ISSN:0003-6951.The luminescence emission of porous Si was regularly measured while immersed in dil. metal ion solns. of Cu, Ag, and Au. The emission spectra show progressive quenching that advances from the blue edge towards the red edge of the emission band, causing a continuous shift in the band center and a narrowing of its width. Auger electron spectroscopy data show that the penetration of the metal adsorbate into the porous layer correlates with the degree of quenching of the luminescence. These results are interpreted as a progression of the quenching of the luminescence inward from the surface of the simple toward the bulk.
- 31Harraz, F. A.; Ismail, A. A.; Bouzid, H.; Al-Sayari, S.; Al-Hajry, A.; Al-Assiri, M. Surface-enhanced Raman scattering (SERS)-active substrates from silver plated-porous silicon for detection of crystal violet. Appl. Surf. Sci. 2015, 331, 241– 247, DOI: 10.1016/j.apsusc.2015.01.04231https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXht1Ogtbs%253D&md5=b126ed65204c882e1273d4c8dbdd5109Surface-enhanced Raman scattering (SERS)-active substrates from silver plated-porous silicon for detection of crystal violetHarraz, Farid A.; Ismail, Adel A.; Bouzid, Houcine; Al-Sayari, S. A.; Al-Hajry, A.; Al-Assiri, M. S.Applied Surface Science (2015), 331 (), 241-247CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Silver nanoparticles (AgNPs) have been reduced onto porous silicon (PSi) surface in a simple immersion plating bath. Here, PSi with av. pore size of ∼30 nm was used as both a mech. support and a mild reducing agent. AgNPs-meso-PSi hybrid structures exhibit a highly sensitive and reproducible surface-enhanced Raman scattering (SERS) response. A detectable concn. as low as 100 pM of crystal violet has been achieved with an enhancement factor (EF) of 1.3 × 106. No aging effect was obsd. for the current substrates after storing in air for three weeks. The large EF is essentially attributed to a combination of electromagnetic enhancement and charge transfer mechanism.
- 32Andsager, D.; Hilliard, J.; Hetrick, J.; AbuHassan, L.; Plisch, M.; Nayfeh, M. Quenching of porous silicon photoluminescence by deposition of metal adsorbates. J. Appl. Phys. 1993, 74 (7), 4783– 4785, DOI: 10.1063/1.35435032https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXktVyktw%253D%253D&md5=e33d454c967b6c39d2429c852589541dQuenching of porous silicon photoluminescence by deposition of metal adsorbatesAndsager, D.; Hillard, J.; Hetrick, J. M.; AbuHassan, L. H.; Plisch, M.; Nayfeh, M. H.Journal of Applied Physics (1993), 74 (7), 4783-5CODEN: JAPIAU; ISSN:0021-8979.Various metals were deposited on luminescent porous silicon (PS) by immersion in metal ion solns. and by evapn. The photoluminescence (PL) was quenched upon immersion in ionic solns. of Cu, Ag, and Au but not noticeably quenched in other ionic solns. Evapn. of 100 Å of Cu or 110 Å of Au was not obsd. to quench PL. Auger electron spectroscopy performed on samples quenched and then immediately removed from soln. showed a metallic concn. in the PS layer of order 10 at.%, but persisting to a depth of order 3000 Å.
- 33Al-Syadi, A.; Faisal, M.; El-Toni, A. M.; Khan, A.; Jalalah, M.; Alsareii, S.; Harraz, F. A. Surface-enhanced Raman scattering (SERS) active substrate from gold nanoparticle-coated porous silicon for sensitive detection of horseradish peroxidase enzyme. Mater. Chem. Phys. 2022, 281, 125931 DOI: 10.1016/j.matchemphys.2022.12593133https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XmtFOhtLw%253D&md5=587272e58e7a7c53cd28fe934b6c1c03Surface-enhanced Raman scattering (SERS) active substrate from gold nanoparticle-coated porous silicon for sensitive detection of horseradish peroxidase enzymeAl-Syadi, A. M.; Faisal, M.; El-Toni, Ahmed Mohamed; Khan, Aslam; Jalalah, Mohammed; Alsareii, S. A.; Harraz, Farid A.Materials Chemistry and Physics (2022), 281 (), 125931CODEN: MCHPDR; ISSN:0254-0584. (Elsevier B.V.)The sensitive detection of horseradish peroxidase (HRP) enzyme using a gold nanoparticle/porous silicon (AuNPs/PSi) active substrate via surface-enhanced Raman scattering (SERS) is demonstrated. Electrochem. porosification via galvanostatic anodization in hydrofluoric acid (HF) mixed with ethanol was used to fabricate mesopore-size PSi layers onto a p-type Si (100) wafer. The AuNPs were reduced onto the meso-PSi surface through a spontaneous galvanic displacement reaction by dipping the substrates in a simple plating bath. The structural features and morphol. of the designed frameworks were elucidated by X-ray diffraction (XRD) anal., field-emission SEM (FESEM), energy-dispersive X-ray spectroscopy (EDX), and XPS. The SERS performance of the AuNPs/PSi substrate was firstly examd. and evaluated using crystal violet dye as the target analyte, where it exhibited enhanced SERS response. Moreover, the active substrate displayed an extremely sensitive and reproducible SERS response toward the HRP enzyme as a reactive analyte. The active substrate exhibited excellent detectable performance with a very low concn. of 10-8 M HRP and an enhancement factor (EF) of approx. 4.8 x 105. The anal. enhancement of Raman signals in response to Au plasmonic nanoparticles signifies the combination of the charge-transfer mechanism and electromagnetic amplification because of the formed d. of hotspot regions. Therefore, the current newly fabricated AuNPs/PSi substrates have optimistic prospects in biophys., biochem., and biomedical applications as highly active SERS substrates.
- 34Coulthard, I.; Jiang, D.; Lorimer, J.; Sham, T.; Feng, X. Reductive deposition of palladium on porous silicon from aqueous solutions of palladium dichloride: an X-ray absorption fine structure study. Langmuir 1993, 9 (12), 3441– 3445, DOI: 10.1021/la00036a01834https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXmsl2ksLw%253D&md5=d93b2d17e918532242307a697b9f8846Reductive deposition of palladium on porous silicon from aqueous solutions of palladium dichloride: an x-ray absorption fine structure studyCoulthard, I.; Jiang, D. T.; Lorimer, J. W.; Sham, T. K.; Feng, X. H.Langmuir (1993), 9 (12), 3441-5CODEN: LANGD5; ISSN:0743-7463.A method for the deposition of Pd on the vast surface of porous Si from aq. solns. of PdCl2 is described. The deposited Pd and the porous Si substrate were characterized by using x-ray absorption fine structure (XAFS) spectroscopy. Deposition can be carried out in a controlled manner, that the deposited Pd is metallic, and that the oxidn.-redn. reaction responsible for the reductive deposition of Pd from PdCl2(aq) takes place at sp. surface sites.
- 35Al-Syadi, A. M.; Faisal, M.; Harraz, F. A.; Jalalah, M.; Alsaiari, M. Immersion-plated palladium nanoparticles onto meso-porous silicon layer as novel SERS substrate for sensitive detection of imidacloprid pesticide. Sci. Rep. 2021, 11 (1), 9174 DOI: 10.1038/s41598-021-88326-035https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhtVSrurrE&md5=f90730d271c8d48fcce381f204bed74fImmersion-plated palladium nanoparticles onto meso-porous silicon layer as novel SERS substrate for sensitive detection of imidacloprid pesticideAl-Syadi, A. M.; Faisal, M.; Harraz, Farid A.; Jalalah, Mohammed; Alsaiari, MabkhootScientific Reports (2021), 11 (1), 9174CODEN: SRCEC3; ISSN:2045-2322. (Nature Research)Herein, we demonstrate the effectiveness of surface-enhanced Raman scattering (SERS) to detect trace concn. of potentially harmful imidacloprid pesticide. To achieve this ultimate objective, a rapid and highly effective methodol. for the fabrication of active and stable porous silicon (PSi) plated palladium nanoparticles (PdNPs) SERS substrates by an electrochem. anodization and immersion plating routes was applied. The PSi layers were fabricated by the electrochem. anodization of a silicon wafer in ethanoic fluoride soln., followed by uniformly deposition of PdNPs via a simple immersion plating technique. The structural features and morphol. of fabricated frameworks of PSi-Pd NPs have been investigated by field emission SEM (FE-SEM) with energy dispersive X-ray (EDX), X-ray diffraction (XRD), XPS and Fourier transform IR (FT-IR) spectra. The SERS signal of imidacloprid using PSi-Pd NPs substrate exhibited immense enhancement compared to the Si-Pd NPs substrate. This large EF is fundamentally ascribed to the combined effect of the electromagnetic improvement and charge transfer mechanisms. Addnl., no aging effect was obsd. for the present substrates kept in air for two weeks. Striking enhancement in Raman spectral signals obtained with the current PSi-Pd NPs substrates can provide a simple and smooth platform towards the sensitive detection of various target analytes.
- 36Jabbar, A. A.; Alwan, A. M. Efficient detecting of TNT molecules using palladium nanoparticles/cross shape pores like structure porous silicon. Vib. Spectrosc. 2019, 103, 102933 DOI: 10.1016/j.vibspec.2019.10293336https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXht1aqtL3O&md5=7a0e386a6388a089153cf1d67f1080f4Efficient detecting of TNT molecules using palladium nanoparticles/ cross shape pores like structure porous siliconJabbar, Allaa A.; Alwan, Alwan M.Vibrational Spectroscopy (2019), 103 (), 102933CODEN: VISPEK; ISSN:0924-2031. (Elsevier B.V.)A set of porous silicon PSi samples with different cross-shaped pores like structures are successfully synthesized by using double successive wet anisotropic etching process: KOH wet chem. process and laser-assisted etching (LAE) process. Four different forms of palladium nanoparticles are deposited on PSi substrate to fabricate PdNPs/PSi heterostructures. Surface-enhanced Raman scattering (SERS)-active PdNPs/PSi heterostructures are fabricated and investigated for detecting Trinitrotoluene (TNT) mols. Dipping plating process of PSi in 0.05 M concn. of PdCl2 soln. at room temp. for 15 min is used to assemble spread of surface morphologies PdNPs layer over PSi. The results show that the SERS of heterostructures for TNT mols. expos strong reliance on the d. of hot-spot junctions more than the local surface plasmonic of PdNPs. Anal. Enhancement factor (EF) of the Raman signal is varied according to the formed d. of hot spots regions.
- 37Ensafi, A. A.; Abarghoui, M. M.; Rezaei, B. Simultaneous determination of morphine and codeine using Pt nanoparticles supported on porous silicon flour modified ionic liquid carbon paste electrode. Sens. Actuators, B 2015, 219, 1– 9, DOI: 10.1016/j.snb.2015.05.01037https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXos1OksLY%253D&md5=228216f1898e1041eaa766fa11518a0fSimultaneous determination of morphine and codeine using Pt nanoparticles supported on porous silicon flour modified ionic liquid carbon paste electrodeEnsafi, Ali A.; Abarghoui, Mehdi Mokhtari; Rezaei, BehzadSensors and Actuators, B: Chemical (2015), 219 (), 1-9CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Pt nanoparticles supported on porous silicon (PSi) flour was synthesized by a simple in-situ redox reaction between PtCl2-6 and PSi, in hydrofluoric acid soln. The components and morphol. properties of Pt/PSi nanocomposites were investigated by means of SEM, X-ray diffraction spectroscopy, energy dispersive X-ray spectroscopy, XPS, cyclic voltammetry and electrochem. impedance spectroscopy. Pt/PSi nanocomposite in carbon ionic liq. electrode (CILE) has synergetic effect on the oxidn. of morphine and codeine. Simultaneous detn. of morphine and codeine were performed using the proposed sensor by means of adsorptive striping voltammetry. Under the optimum conditions, the oxidn. current responses of morphine and codeine were linear in the concn. range of 0.10-25.0 μmol L-1. The detection limits of 30.0 and 20.0 nmol L-1 were achieved for morphine and codeine, resp. The electrochem. sensor has high sensitivity toward the analytes with a good reproducibility (due to the high synergetic activity of Pt nanoparticles and good antifouling properties of the ionic liq.). To check the applicability of the sensor, the proposed sensor was used for the simultaneous detn. of morphine and codeine in biol. fluids with satisfactory results.
- 38Harraz, F. A.; Sakka, T.; Ogata, Y. H. Immersion plating of nickel onto a porous silicon layer from fluoride solutions. Phys. Status Solidi A 2003, 197 (1), 51– 56, DOI: 10.1002/pssa.20030646738https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXkt1Ontb8%253D&md5=6a5335861efc34a86fa9dce58941dd94Immersion plating of nickel onto a porous silicon layer from fluoride solutionsHarraz, F. A.; Sakka, T.; Ogata, Y. H.Physica Status Solidi A: Applied Research (2003), 197 (1), 51-56CODEN: PSSABA; ISSN:0031-8965. (Wiley-VCH Verlag GmbH & Co. KGaA)The deposition of nickel (Ni) onto a porous silicon (PS) layer by immersion plating from acidic and alk. fluoride solns. was studied. In an immersion plating bath of simple hydrofluoric acid (HF) of pH 2 contg. Ni ions, no metal deposition was obsd. However, visible metallic Ni was deposited from the ammonium fluoride (NH4F) alk. soln. of pH 8. The different deposition behaviors are discussed from mixed potential theory, etching rate of PS and the state of Ni complex formation. The modified PS layers after the immersion plating were analyzed by x-ray diffraction and XPS. FTIR spectroscopy and SEM were also performed to study the structural changes and characterizations of PS samples after the plating process. A binary PS/Ni nanostructure without Si oxides is successfully achieved from the alk. bath.
- 39Sham, T. K.; Coulthard, I.; Lorimer, J.; Hiraya, A.; Watanabe, M. Reductive deposition of Cu on porous silicon from aqueous solutions: An X-ray absorption study at the Cu L3, 2 edge. Chem. Mater. 1994, 6 (11), 2085– 2091, DOI: 10.1021/cm00047a03139https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXms1Cksbs%253D&md5=bf29f76d2d43239fb10b9f4e6268c950Reductive Deposition of Cu on Porous Silicon from Aqueous Solutions: An X-ray Absorption Study at the Cu L3,2 EdgeSham, T. K.; Coulthard, I.; Lorimer, J. W.; Hiraya, A.; Watanabe, M.Chemistry of Materials (1994), 6 (11), 2085-91CODEN: CMATEX; ISSN:0897-4756.The reductive deposition of metallic Cu on porous silicon (PS) surface from aq. soln. of Cu2+(aq) ions is reported. X-ray absorption near-edge structure (XANES) at the Cu L3,2 edge has been used to characterize these samples. The redn. of Cu2+(aq) to Cu occurs readily at room temp. and appears to be controlled by the availability of active sites as well as the concn. of Cu2+(aq) and that only a very thin film of Cu is formed even with concd. solns. The surface of Cu/PS is oxidized when exposed to the ambient atm. The spectroscopic features and the implication of the results are discussed.
- 40Coulthard, I.; Degen, S.; Zhu, Y.-J.; Sham, T. Gold nanoclusters reductively deposited on porous silicon: morphology and electronic structures. Can. J. Chem. 1998, 76 (11), 1707– 1716, DOI: 10.1139/v98-14640https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXhslWmtLo%253D&md5=7a0b739fd52d01ca87ab0e9857c16802Gold nanoclusters reductively deposited on porous silicon: morphology and electronic structuresCoulthard, I.; Degen, S.; Zhu, Y.-J.; Sham, T. K.Canadian Journal of Chemistry (1998), 76 (11), 1707-1716CODEN: CJCHAG; ISSN:0008-4042. (National Research Council of Canada)Using porous silicon as a reducing agent and a substrate, gold complex ions [AuCl4]- were reduced from aq. soln. to produce nanoparticles of gold upon the surface of porous silicon. SEM was used to study the morphol. of the porous silicon layers and the deposits of gold nanoparticles. It is found that prepn. conditions have a profound effect on the morphol. of the deposits, esp. on porous silicon prepd. from a p-type wafer. The gold nanoparticles, varying from micrometric aggregates of clusters of the order of 10 nm, to a distribution of nearly spherical clusters of the order of 10 nm, to strings of ∼10 nm were obsd. and compared to bulk gold metal using x-ray diffraction (XRD), XPS, and x-ray absorption spectroscopy (XAS). These techniques confirm and complement the SEM findings. The potential for this reductive deposition technique is noted.
- 41Wali, L. A.; Hasan, K. K.; Alwan, A. M. An investigation of efficient detection of ultra-low concentration of penicillins in milk using AuNPs/PSi hybrid structure. Plasmonics 2020, 15 (4), 985– 993, DOI: 10.1007/s11468-019-01096-441https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXjtFSntLo%253D&md5=8b413e075c2c716d9fc2f2c8e160bddaAn Investigation of Efficient Detection of Ultra-Low Concentration of Penicillins in Milk Using AuNPs/PSi Hybrid StructureWali, Layla A.; Hasan, Khulood K.; Alwan, Alwan M.Plasmonics (2020), 15 (4), 985-993CODEN: PLASCS; ISSN:1557-1955. (Springer)In this work, porous silicon (PSi) sample was employed to increase the SERS efficiency for rapid detection of penicillins in spiked milk by developing Au nanoparticles (AuNPs)/PSi hybrid structure. SERS was used to study penicillin G and ampicillin residue in milk. The results show that the AuNPs/PSi hybrid structure is very able to detect penicillins residue in milk with an excellent linear relationship and a correlation coeff. (R2 = 1) in the range of 1 × 10-7 mol/L to 1 × 10-9 mol/L. The highest enhancement factors of penicillin G (2.8 × 108) and of ampicillin (1.2 × 108) with an excellent relative std. deviation (RSD) of 2.69 and 0.93, resp., are obtained at the ultra-low concn. of 1 × 10-9 mol/L. The detection limit of penicillin G and ampicillin is 1 × 10-9 mol/L (equal to 0.33μg/kg and 0.35μg/kg, resp.) which is very lower than the max. residue limit (MRL) of penicillins in milk (4μg/kg) established by the European Union.
- 42Bandarenka, H. V.; Girel, K. V.; Zavatski, S. A.; Panarin, A.; Terekhov, S. N. Progress in the development of SERS-active substrates based on metal-coated porous silicon. Materials 2018, 11 (5), 852, DOI: 10.3390/ma1105085242https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhsVSns77K&md5=6aec61a3fca120907cee21dab09bb815Progress in the development of SERS-active substrates based on metal-coated porous siliconBandarenka, Hanna V.; Girel, Kseniya V.; Zavatski, Sergey A.; Panarin, Andrei; Terekhov, Sergei N.Materials (2018), 11 (5), 852/1-852/20CODEN: MATEG9; ISSN:1996-1944. (MDPI AG)The present work gives an overview of the developments in surface-enhanced Raman scattering (SERS) with metal-coated porous silicon used as an active substrate. We focused this review on the research referenced to SERS-active materials based on porous silicon, beginning from the patent application in 2002 and enclosing the studies of this year. Porous silicon and metal deposition technologies are discussed. Since the earliest studies, a no. of fundamentally different plasmonic nanostructures including metallic dendrites, quasi-ordered arrays of metallic nanoparticles (NPs), and metallic nanovoids have been grown on porous silicon, defined by the morphol. of this host material. SERS-active substrates based on porous silicon have been found to combine a high and well-reproducible signal level, storage stability, cost-effective technol. and handy use. They make it possible to identify and study many compds. including biomols. with a detection limit varying from milli- to femtomolar concns. The progress reviewed here demonstrates the great prospects for the extensive use of the metal-coated porous silicon for bioanal. by SERS-spectroscopy.
- 43Khinevich, N.; Bandarenka, H.; Zavatski, S.; Girel, K.; Tamulevičienė, A.; Tamulevičius, T.; Tamulevičius, S. Porous silicon-A versatile platform for mass-production of ultrasensitive SERS-active substrates. Microporous Mesoporous Mater. 2021, 323, 111204 DOI: 10.1016/j.micromeso.2021.11120443https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsVagsrnK&md5=4af03ccf3c5e05d4e35eb161a1ad786aPorous silicon - A versatile platform for mass-production of ultrasensitive SERS-active substratesKhinevich, Nadzeya; Bandarenka, Hanna; Zavatski, Siarhei; Girel, Kseniya; Tamuleviciene, Asta; Tamulevicius, Tomas; Tamulevicius, SigitasMicroporous and Mesoporous Materials (2021), 323 (), 111204CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)A review. Surface-enhanced Raman scattering (SERS) spectroscopy is one of the most prospective methods combining state-of-the-art nanomaterials and optical techniques for highly sensitive express-anal. and detection of org. and bioorg. objects in liqs. and gases. Special programs have been recently started all over the world to bring the SERS-spectroscopy closer to wide implementation in medical diagnostics, forensics, security, monitoring sanitary conditions, etc. Despite outstanding features of SERS-spectroscopy, its effective practical use has been particularly slowed down by moderate reproducibility, non-versatility, and restrictions imposed by com. available SERS-active substrates to measurement and storage regimes. The present reports SERS-active substrates constituted by noble metals' nanoparticles (NPs) and porous silicon (PS), which potentially can be a tool to overcome the above-mentioned limitations. The PS template acts as a highly ordered host nanomaterial for the formation of a variety of metallic nanostructures, which morphol. and optical properties can be easily tuned for the best performance to meet the customer requirements via managing PS synthesis regimes. An indubitable advantage of PS is the compatibility of its fabrication process with basic microelectronics operations and micro-electro mech. systems (MEMS) that make it possible to integrate SERS-active areas in a silicon chip. In contrast to the previously published s in the field, this one covers the most recent results on formation, characterization, and application of PS-based substrates demonstrating prominent SERS-activity that have been achieved for the last decade including modifications with graphene or Bragg structures, detection of mols. at amt. down to attomolar concn. bacteria recognition, etc.
- 44Liu, X.; Cheng, H.; Cui, P. Catalysis by silver nanoparticles/porous silicon for the reduction of nitroaromatics in the presence of sodium borohydride. Appl. Surf. Sci. 2014, 292, 695– 701, DOI: 10.1016/j.apsusc.2013.12.03644https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXpsV2k&md5=58dacecc5cb01c5ef3a2f4c0d90b2173Catalysis by silver nanoparticles/porous silicon for the reduction of nitroaromatics in the presence of sodium borohydrideLiu, Xiang; Cheng, Heming; Cui, PingApplied Surface Science (2014), 292 (), 695-701CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)A facile approach of prepg. well-dispersed silver nanoparticles (Ag NPs) which fabricated on surface of porous silicon (PSi) generating Ag NPs/PSi chip and the catalyzes towards redn. of nitro aroms. are described in detail in this work. Aq. silver ions are reduced readily by the surface SiHx (x =1, 2 or 3) species of PSi within dozens of seconds at room temp. The resulted Ag NPs are demonstrated by scanning and transmission electron microscopes, UV-visible spectrum and X-ray powder diffraction. A proposed mechanism of forming Ag NPs on PSi chip is discussed in light of the obsd. phenomena and the analyses of IR and energy dispersive X-ray spectra. The stably porous architecture of PSi and the well-dispersed Ag NPs on PSi surface guarantee the highly catalytic activities of the Ag NPs/PSi chip. The progresses of reducing nitro aroms. catalyzed by the Ag NPs/PSi chip in the presence of sodium borohydride are traced by UV-visible measurements to est. the catalytic performance of the Ag NPs/PSi chip.
- 45Polisski, S.; Goller, B.; Wilson, K.; Kovalev, D.; Zaikowskii, V.; Lapkin, A. In situ synthesis and catalytic activity in CO oxidation of metal nanoparticles supported on porous nanocrystalline silicon. J. Catal. 2010, 271 (1), 59– 66, DOI: 10.1016/j.jcat.2010.02.00245https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXjslGrtb0%253D&md5=b4bbc1860c3ff93f9817a148561255faIn situ synthesis and catalytic activity in CO oxidation of metal nanoparticles supported on porous nanocrystalline siliconPolisski, Sergej; Goller, Bernhard; Wilson, Karen; Kovalev, Dmitry; Zaikowskii, Vladimir; Lapkin, AlexeiJournal of Catalysis (2010), 271 (1), 59-66CODEN: JCTLA5; ISSN:0021-9517. (Elsevier Inc.)The reactive surface of meso-porous, nanocryst. Si was used to synthesize noble metal nanoparticles by in-situ redn. of precursor salt solns. The synthetic method for metal nanoparticle formation was systematically developed; reaction conditions for metal salts redn. were optimized to prep. nanoparticles with controlled size distribution on the order 5-10 nm inside the meso-porous Si template. CO oxidn. was used as a test reaction for synthesized Pt/porous Si catalysts. Sharp reaction light-off was obsd. at ∼120° on optimized catalysts. Catalysts were stable in extended steady-state runs and in catalysts re-use expts. Metal nanoparticles were stable to sintering at elevated temps. ≤1000°. However, following thermal treatment in air, Pt nanoparticles were covered by a SiOx layer and were less active for CO oxidn.
- 46Halim, M.; Tan, W. L.; Abu Bakar, N. H. H.; Abu Bakar, M. Surface characteristics and catalytic activity of copper deposited porous silicon powder. Materials 2014, 7 (12), 7737– 7751, DOI: 10.3390/ma712773746https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1cflsF2huw%253D%253D&md5=620176015cc04e7a2d4b03e5c8e8041cSurface Characteristics and Catalytic Activity of Copper Deposited Porous Silicon PowderHalim Muhammad Yusri Abdul; Tan Wei Leng; Bakar Noor Hana Hanif Abu; Bakar Mohamad AbuMaterials (Basel, Switzerland) (2014), 7 (12), 7737-7751 ISSN:1996-1944.Porous structured silicon or porous silicon (PS) powder was prepared by chemical etching of silicon powder in an etchant solution of HF: HNO3: H2O (1:3:5 v/v). An immersion time of 4 min was sufficient for depositing Cu metal from an aqueous solution of CuSO4 in the presence of HF. Scanning electron microscopy (SEM) analysis revealed that the Cu particles aggregated upon an increase in metal content from 3.3 wt% to 9.8 wt%. H2-temperature programmed reduction (H2-TPR) profiles reveal that re-oxidation of the Cu particles occurs after deposition. Furthermore, the profiles denote the existence of various sizes of Cu metal on the PS. The Cu-PS powders show excellent catalytic reduction on the p-nitrophenol regardless of the Cu loadings.
- 47Hernández-Montelongo, J.; Fernández-Fierro, C.; Benito-Gómez, N.; Romero-Saez, M.; Parodi, J.; Carmona, E. R.; Recio-Sánchez, G. Hybrid porous silicon/green synthetized Ag microparticles as potential carries for Ag nanoparticles and drug delivery. Mater. Sci. Eng. C 2020, 116, 111183 DOI: 10.1016/j.msec.2020.11118347https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXht1CqtL3I&md5=f7068d7e9075e146b7da55704028e77eHybrid porous silicon/green synthetized Ag microparticles as potential carries for Ag nanoparticles and drug deliveryHernandez-Montelongo, Jacobo; Fernandez-Fierro, Cristian; Benito-Gomez, Noelia; Romero-Saez, Manuel; Parodi, Jorge; Carmona, Erico R.; Recio-Sanchez, GonzaloMaterials Science & Engineering, C: Materials for Biological Applications (2020), 116 (), 111183CODEN: MSCEEE; ISSN:0928-4931. (Elsevier B.V.)In the present work, the fabrication of hybrid porous silicon/green synthesized Ag microparticles was shown and the potential use as carriers for Ag nanoparticles and drug delivery was explored. Hybrid microparticles were fabricated by incorporating green synthesized Ag nanoparticles into porous silicon matrix. The main physicochem. characteristics of the hybrid systems were studied by several techniques including UV-vis spectroscopy, TEM, SEM, XRD and XPS. The toxicol. of these hybrid systems was investigated by cell viability, MTT, and comet assays. In addn., the possibility to aggregate different drug to use as drug delivery system was demonstrated by using florfenicol as drug model, due to its importance in salmon industry. The exptl. results showed the potential to use these hybrid systems as carries for drug delivery in salmon industry.
- 48Hernandez, M.; Recio, G.; Martin-Palma, R. J.; Garcia-Ramos, J. V.; Domingo, C.; Sevilla, P. Surface enhanced fluorescence of anti-tumoral drug emodin adsorbed on silver nanoparticles and loaded on porous silicon. Nanoscale Res. Lett. 2012, 7, 364, DOI: 10.1186/1556-276X-7-36448https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsVWhs7rK&md5=3222a6c4f711cb6f04ff0f30dadf773dSurface enhanced fluorescence of anti-tumoral drug emodin adsorbed on silver nanoparticles and loaded on porous siliconHernandez, Margarita; Recio, Gonzalo; Martin-Palma, Raul J.; Garcia-Ramos, Jose V.; Domingo, Concepcion; Sevilla, PazNanoscale Research Letters (2012), 7 (1), 364, 7 pp.CODEN: NRLAAD; ISSN:1556-276X. (Springer)Fluorescence spectra of anti-tumoral drug emodin loaded on nanostructured porous silicon have been recorded. The use of colloidal nanoparticles allowed embedding of the drug without previous porous silicon functionalization and leads to the observation of an enhancement of fluorescence of the drug. Mean pore size of porous silicon matrixes was 60 nm, while silver nanoparticles mean diam. was 50 nm. Atm. and vacuum conditions at room temp. were used to infiltrate emodin-silver nanoparticles complexes into porous silicon matrixes. The drug was loaded after adsorption on metal surface, alone, and bound to bovine serum albumin. Methanol and water were used as solvents. Spectra with 1 μm spatial resoln. of cross-section of porous silicon layers were recorded to observe the penetration of the drug. A max. fluorescence enhancement factor of 24 was obtained when protein was loaded bound to albumin, and atm. conditions of inclusion were used. A better penetration was obtained using methanol as solvent when comparing with water. Complexes of emodin remain loaded for 30 days after prepn. without an apparent degrdn. of the drug, although a decrease in the enhancement factor is obsd. The study reported here constitutes the basis for designing a new drug delivery system with future applications in medicine and pharmacy.
- 49Lin, T.; Zhong, L.; Guo, L.; Fu, F.; Chen, G. Seeing diabetes: visual detection of glucose based on the intrinsic peroxidase-like activity of MoS2 nanosheets. Nanoscale 2014, 6 (20), 11856– 11862, DOI: 10.1039/C4NR03393K49https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1ylt7nN&md5=47e5a74f612da163694c3016fe739511Seeing diabetes: visual detection of glucose based on the intrinsic peroxidase-like activity of MoS2 nanosheetsLin, Tianran; Zhong, Liangshuang; Guo, Liangqia; Fu, Fengfu; Chen, GuonanNanoscale (2014), 6 (20), 11856-11862CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Molybdenum disulfide (MoS2) has attracted increasing research interest recently due to its unique phys., optical and elec. properties, correlated with its 2D ultrathin at.-layered structure. Until now, however, great efforts have focused on its applications such as lithium ion batteries, transistors, and hydrogen evolution reactions. Herein, for the first time, MoS2 nanosheets are discovered to possess an intrinsic peroxidase-like activity and can catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a color reaction. The catalytic activity follows the typical Michaelis-Menten kinetics and is dependent on temp., pH, H2O2 concn., and reaction time. Based on this finding, a highly sensitive and selective colorimetric method for H2O2 and glucose detection is developed and applied to detect glucose in serum samples. Moreover, a simple, inexpensive, instrument-free and portable test kit for the visual detection of glucose in normal and diabetic serum samples is constructed by utilizing agarose hydrogel as a visual detection platform.
- 50Masud, M. K.; Kim, J.; Billah, M. M.; Wood, K.; Shiddiky, M. J.; Nguyen, N.-T.; Parsapur, R. K.; Kaneti, Y. V.; Alshehri, A. A.; Alghamidi, Y. G. Nanoarchitectured peroxidase-mimetic nanozymes: mesoporous nanocrystalline α-or γ-iron oxide?. J. Mater. Chem. B 2019, 7 (35), 5412– 5422, DOI: 10.1039/C9TB00989B50https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhsFyjurnL&md5=f659d0e439ecbf3fcabe1da2e3c21a3cNanoarchitectured peroxidase-mimetic nanozymes: mesoporous nanocrystalline α- or γ-iron oxide?Masud, Mostafa Kamal; Kim, Jeonghun; Billah, Md. Motasim; Wood, Kathleen; Shiddiky, Mohammad J. A.; Nguyen, Nam-Trung; Parsapur, Rajesh Kumar; Kaneti, Yusuf Valentino; Alshehri, Abdulmohsen Ali; Alghamidi, Yousef Gamaan; Alzahrani, Khalid Ahmed; Adharvanachari, Murugulla; Selvam, Parasuraman; Hossain, Md. Shahriar A.; Yamauchi, YusukeJournal of Materials Chemistry B: Materials for Biology and Medicine (2019), 7 (35), 5412-5422CODEN: JMCBDV; ISSN:2050-7518. (Royal Society of Chemistry)Nanozymes (nanoparticles with enzyme-like properties) have attracted considerable attention in recent years owing to their intrinsic enzyme-like properties and broad application in the fields of ELISA based immunoassay and biosensing. Herein, the authors systematically study the influence of crystal phases (γ-Fe2O3 and α-Fe2O3) of mesoporous iron oxide (IO) on their peroxidase mimetic activity. In addn., the authors also demonstrated the applicability of these mesoporous IOs as nanozymes for detecting the glucose biomarker with a limit of detection (LOD) of 0.9 μM. Mesoporous γ-Fe2O3 shows high nanozyme activities (and magnetism) toward the catalytic oxidn. of chromogenic substances, such as 3,3',5,5'-tetramethylbenzidine (TMB) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)-ABTS, as well as for the colorimetric detection of glucose, compared to that of α-Fe2O3. The authors believe that this in-depth study of crystal structure based nanozyme activity will guide designing highly effective nanozymes based on iron oxide nanostructures for chem. sensing, biosensing and environmental remediation.
- 51Lehninger, A. L.; Nelson, D. L.; Cox, M. M.; Cox, M. M. Lehninger Principles of Biochemistry; Macmillan, 2005.There is no corresponding record for this reference.
- 52Nabil, M.; Motaweh, H. A. Enhanced thermal stability of promising nano-porous silicon powder. Adv. Nanopart. 2016, 05 (04), 199– 205, DOI: 10.4236/anp.2016.5402152https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtFajsbfE&md5=60b42ee527c33095054ef8aba2651535Enhanced thermal stability of promising nano-porous silicon powderNabil, Marwa; Motaweh, Hussien A.Advances in Nanoparticles (2016), 5 (4), 199-205CODEN: ANDAA6; ISSN:2169-0529. (Scientific Research Publishing, Inc.)A direct synthesis method is introduced to prep. nano-porous silicon-nickel nanocomposite (nPS/Ni) powder for thermal isolation applications. In this paper, we study the thermal stability of nanocomposites consisting of nanoparticles metal incorporated into the pores of a porous silicon by a very simple method. The nickel element is chem. deposited whereas the nanoparticles are pptd. on the pore surfaces. The (nPS) and (nPS/Ni) nano-materials are thermally measured under nitrogen at temps. of 40°C - 1000°C, noticeable, demonstrating better thermal stability of (nPS/Ni) until 900°C than in the case of (nPS) at 600°C. Then, the improving of the thermal stability of the nPS powder is facilitated using it in many applications of the thermal insulation process.
- 53Ren, X.; Song, Y.; Liu, A.; Zhang, J.; Yang, P.; Zhang, J.; An, M. Experimental and theoretical studies of DMH as a complexing agent for a cyanide-free gold electroplating electrolyte. RSC Adv. 2015, 5 (80), 64997– 65004, DOI: 10.1039/C5RA13140E53https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFylu7%252FM&md5=68a18a0d373d6cc0cde2f65c1c34d390Experimental and theoretical studies of DMH as a complexing agent for a cyanide-free gold electroplating electrolyteRen, Xuefeng; Song, Ying; Liu, Anmin; Zhang, Jie; Yang, Peixia; Zhang, Jinqiu; An, MaozhongRSC Advances (2015), 5 (80), 64997-65004CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)In this study, a cyanide-free gold electroplating electrolyte using 5,5-dimethylhydantoin (DMH) as a complexing agent was introduced. A golden bright gold electrodeposit with smooth and compact surface was obtained from the introduced cyanide-free gold electroplating electrolyte. The results of SEM (SEM) measurements confirmed that the golden bright gold electrodeposit possesses an excellent leveling capability as well as smooth and compact morphol. The cryst. structure of the gold electrodeposits was characterized by X-ray diffraction (XRD) anal. Computational chem. was employed to provide an insight view of the reason for selecting DMH among the various hydantoin derivs. as the complexing agent for the introduced cyanide-free gold electroplating electrolyte. Quantum chem. calcns. were employed to study the electronic properties and orbital information of the investigated complexing agents. The adsorption interactions between these complexing agents and the metal surfaces were investigated by mol. dynamic (MD) simulations. Consequently, the results of these theor. studies revealed that DMH was selected among the various hydantoin derivs. as the complexing agent for the introduced cyanide-free gold electroplating electrolyte due to its strong electron donating abilities and high adsorption energies on the metal surfaces.
- 54Boriachek, K.; Masud, M. K.; Palma, C.; Phan, H.-P.; Yamauchi, Y.; Hossain, M. S. A.; Nguyen, N.-T.; Salomon, C.; Shiddiky, M. J. Avoiding pre-isolation step in exosome analysis: direct isolation and sensitive detection of exosomes using gold-loaded nanoporous ferric oxide nanozymes. Anal. Chem. 2019, 91 (6), 3827– 3834, DOI: 10.1021/acs.analchem.8b0361954https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXivVOit7k%253D&md5=85486a32ff7b3fa135c4a19926746319Avoiding Pre-Isolation Step in Exosome Analysis: Direct Isolation and Sensitive Detection of Exosomes Using Gold-Loaded Nanoporous Ferric Oxide NanozymesBoriachek, Kseniia; Masud, Mostafa Kamal; Palma, Carlos; Phan, Hoang-Phuong; Yamauchi, Yusuke; Hossain, Md. Shahriar A.; Nguyen, Nam-Trung; Salomon, Carlos; Shiddiky, Muhammad J. A.Analytical Chemistry (Washington, DC, United States) (2019), 91 (6), 3827-3834CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)Most of the current exosome-anal. strategies are time-consuming and largely dependent on com. extn. kit-based preisolation step, which requires extensive sample manipulations, costly isolation kits, reagents, tedious procedures, and sophisticated equipment and is prone to bias/artifacts. Herein we introduce a simple method for direct isolation and subsequent detection of a specific population of exosomes using an engineered superparamagnetic material with multifunctional properties, namely, gold-loaded ferric oxide nanocubes (Au-NPFe2O3NC). In this method, the Au-NPFe2O3NC were initially functionalized with a generic tetraspanin (exosomes-assocd.) antibody (i.e., CD63) and dispersed in sample fluids where they work as "dispersible nanocarriers" to capture the bulk population of exosomes. After magnetic collection and purifn., Au-NPFe2O3NC-bound exosomes were transferred to the tissue-specific, antibody-modified, screen-printed electrode. As a proof of principle, we used a specific placental marker, placenta alk. phosphatase (PLAP), to detect exosomes secreted from placental cells. The peroxidase-like activity of Au-NPFe2O3NC was then used to accomplish an ELISA-based sensing protocol for naked-eye observation along with UV-visible and electrochem. detection of PLAP-specific exosomes present in placental cell-conditioned media. We demonstrated excellent agreement in anal. performance for the detection of placental cell-derived exosomes (i.e., linear dynamic range, 103-107 exosomes/mL; limit of detection, 103 exosomes/mL; relative std. deviation (%RSD) of <5.5% for n = 3) using with and without com. "total exosome isolation kit"-based preisolation step. We envisage that this highly sensitive, rapid, and inexpensive assay could be useful in quantifying specific populations of exosomes for various clin. applications, focusing on pregnancy complications.
- 55Gurol, M. D.; Lin, S.-S. Hydrogen peroxide/iron oxide-induced catalytic oxidation of organic compounds. J. Adv. Oxid. Technol. 2002, 5 (2), 147– 154, DOI: 10.1515/jaots-2002-020455https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38Xmt1Ohu7o%253D&md5=443bf5a3066079b82f95f2e1ebceeb41Hydrogen peroxide/iron oxide-induced catalytic oxidation of organic compoundsGurol, Mirat D.; Lin, Shu-SungJournal of Advanced Oxidation Technologies (2002), 5 (2), 147-154CODEN: JAOTFT; ISSN:1203-8407. (Science & Technology Network, Inc.)This paper describes a novel heterogeneous catalytic oxidn. process involving the use of hydrogen peroxide (H2O2) with granular size iron oxide particles (α-FeOOH) in aq. phase. The generation of hydroxyl radical (•OH) in the process is demonstrated through the use of a probe chem., n-chlorobutane (BuCl). Based on the exptl. evidence, it is concluded that the •OH, which is produced through the interaction of H2O2 with the surface sites, reacts with solutes adsorbed on the goethite surface, causing oxidn. of the org. compds. The generation rate of •OH increases slightly with increasing pH in the range of 5-9. The oxidn. rate of BuCl by •OH is relatively insensitive to the level of bicarbonate ion in subject water due to low affinity of bicarbonate for the surface. Phosphate, on the other hand, inhibits the oxidn. rate by preferential adsorption on the surface. This new process provides a viable alternative to the existing oxidn. technologies, esp. when water has high alky., and/or it is desired to selectively oxidize target compds. that have high affinity for the surface.
- 56Motherwell, W.; Bingham, M.; Six, Y. Recent progress in the design and synthesis of artificial enzymes. Tetrahedron 2001, 57 (22), 4663– 4686, DOI: 10.1016/S0040-4020(01)00288-556https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXjslehsrk%253D&md5=bdf403f3b4b8bd16e76a6a5c56e7c28bRecent progress in the design and synthesis of artificial enzymesMotherwell, W. B.; Bingham, M. J.; Six, Y.Tetrahedron (2001), 57 (22), 4663-4686CODEN: TETRAB; ISSN:0040-4020. (Elsevier Science Ltd.)A review with 111 refs., which details recent progress in the design and synthesis of artificial enzymes, such as cyclodextrins and catalytic antibodies. Particular emphasis is given to some of the more recent developments in 'selection approaches' toward enzyme mimics. Furthermore, dynamic combinatorial libraries and related research is described with ref. to possible applications in the field of artificial enzymes.
- 57Chen, W.; Chen, J.; Liu, A. L.; Wang, L. M.; Li, G. W.; Lin, X. H. Peroxidase-like activity of cupric oxide nanoparticle. ChemCatChem 2011, 3 (7), 1151– 1154, DOI: 10.1002/cctc.20110006457https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXotFyjsbg%253D&md5=f3a88cea985308497b69df6a881d410bPeroxidase-Like Activity of Cupric Oxide NanoparticleChen, Wei; Chen, Juan; Liu, Ai-Lin; Wang, Li-Man; Li, Guang-Wen; Lin, Xin-HuaChemCatChem (2011), 3 (7), 1151-1154CODEN: CHEMK3; ISSN:1867-3880. (Wiley-VCH Verlag GmbH & Co. KGaA)It is well known that peroxidase can catalyze the oxidn. of a peroxidase substrate by hydrogen peroxide to produce a color change. Upon the addn. of cupric oxide nanoparticles (CuO NPs) to the peroxidase substrate TMB in the presence of H2O2, a blue color product can be formed with a max. absorbance at A = 652nm, indicating that cupric oxide nanoparticles have peroxidase-like catalytic activity.
- 58Pankhurst, Q. A.; Thanh, N.; Jones, S.; Dobson, J. Progress in applications of magnetic nanoparticles in biomedicine. J. Phys. D: Appl. Phys. 2009, 42 (22), 224001 DOI: 10.1088/0022-3727/42/22/22400158https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsFeksr%252FM&md5=b18381643f157f66a155154560582b25Progress in applications of magnetic nanoparticles in biomedicinePankhurst, Q. A.; Thanh, N. K. T.; Jones, S. K.; Dobson, J.Journal of Physics D: Applied Physics (2009), 42 (22), 224001/1-224001/15CODEN: JPAPBE; ISSN:0022-3727. (Institute of Physics Publishing)A review and progress report on a selection of scientific, technol., and com. advances in the biomedical applications of magnetic nanoparticles since 2003. Particular attention is paid to (1) magnetic actuation for in vitro nonviral transfection and tissue engineering and in vivo drug delivery and gene therapy, (2) recent clin. results for magnetic hyperthermia treatments of brain and prostate cancer via direct injection, and continuing efforts to develop new agents suitable for targeted hyperthermia following i.v. injection, and (3) developments in medical sensing technologies involving a new generation of magnetic resonance imaging contrast agents, and the invention of magnetic particle imaging as a new modality. Ongoing prospects are also discussed.
- 59Dutta, A. K.; Maji, S. K.; Srivastava, D. N.; Mondal, A.; Biswas, P.; Paul, P.; Adhikary, B. Peroxidase-like activity and amperometric sensing of hydrogen peroxide by Fe2O3 and Prussian Blue-modified Fe2O3 nanoparticles. J. Mol. Catal. A 2012, 360, 71– 77, DOI: 10.1016/j.molcata.2012.04.01159https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XotVajtbw%253D&md5=180d1bace63f4efcc8031595eb156372Peroxidase-like activity and amperometric sensing of hydrogen peroxide by Fe2O3 and Prussian Blue-modified Fe2O3 nanoparticlesDutta, Amit Kumar; Maji, Swarup Kumar; Srivastava, Divesh N.; Mondal, Anup; Biswas, Papu; Paul, Parimal; Adhikary, BibhutoshJournal of Molecular Catalysis A: Chemical (2012), 360 (), 71-77CODEN: JMCCF2; ISSN:1381-1169. (Elsevier B.V.)Nano-sized crystals of iron oxide (Fe2O3) was synthesized from a single-source precursor complex [Fe3(μ3-O)(O2CCH2Cl)6(H2O)3]NO3·H2O by solvothermal process. Afterward it was chem. modified with electro-active Prussian Blue (PB). The resulting Fe2O3 and PB-Fe2O3 nanoparticles (NPs) were characterized by x-ray diffraction anal. (XRD), TEM, UV-visible and IR spectroscopic techniques. Structural analyses showed that the av. diam. of hexagonal Fe2O3 (maghemite) and PB-Fe2O3 NPs are 40 and 46 nm, resp. The as-synthesized nanocomposite (PB-Fe2O3 NPs) showed superior catalytic activity toward oxidn. of peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in presence of H2O2 and follow typical Michaelis-Menten kinetics. Also, the nanocomposite, immobilized on surface of a glassy carbon electrode (GCE), exhibited electrocatalytic activity toward redn. of hydrogen peroxide and can be used for its amperometric detection.
- 60Wei, H.; Wang, E. Fe3O4 magnetic nanoparticles as peroxidase mimetics and their applications in H2O2 and glucose detection. Anal. Chem. 2008, 80 (6), 2250– 2254, DOI: 10.1021/ac702203f60https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXit1Gqu7c%253D&md5=c381fb01daf41a50573d097f28d41396Fe3O4 Magnetic Nanoparticles as Peroxidase Mimetics and Their Applications in H2O2 and Glucose DetectionWei, Hui; Wang, ErkangAnalytical Chemistry (Washington, DC, United States) (2008), 80 (6), 2250-2254CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)Artificial enzyme mimetics are a current research interest because natural enzymes bear some serious disadvantages, such as their catalytic activity can be easily inhibited and they can be digested by proteases. A very recent study reported by L. Z. Gao et al. (2007) has proven that Fe3O4 magnetic nanoparticles (MNPs) exhibit an intrinsic enzyme mimetic activity similar to that found in natural peroxidases, though MNPs are usually thought to be biol. and chem. inert. In the present work, the authors just make use of the novel properties of Fe3O4 MNPs as peroxidase mimetics to detect H2O2. The Fe3O4 MNPs were prepd. via a copptn. method. The as-prepd. Fe3O4 MNPs were then used to catalyze the oxidn. of a peroxidase substrate 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) by H2O2 to the oxidized colored product which provides a colorimetric detection of H2O2. As low as 3 × 10-6 mol/L H2O2 could be detected with a linear range from 5 × 10-6 to 1 × 10-4 mol/L via the authors' method. More importantly, a sensitive and selective method for glucose detection was developed using glucose oxidase (GOx) and the as-prepd. Fe3O4 MNPs. The detection platforms for H2O2 and glucose developed in the present work not only further confirmed that the Fe3O4 MNPs possess intrinsic peroxidase-like activity but also showed great potential applications in varieties of simple, robust, and easy-to-make anal. approaches in the future.
- 61Karaseva, E. I.; Losev, Y. P.; Metelitsa, D. Peroxidase-catalyzed Oxidation of 3, 3″, 5, 5″-Tetramethylbenzidine in the Presence of 2, 4-Dinitrosoresorcinol and Polydisulfide Derivatives of Resorcinol and 2, 4-Dinitrosoresorcinol. Russ. J. Bioorg. Chem. 2002, 28 (2), 128– 135, DOI: 10.1023/A:101506942425161https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XjtlWmsbg%253D&md5=da12696dae5f1453c1d907a9695664efPeroxidase-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine in the presence of 2,4-dinitrosoresorcinol and polydisulfide derivatives of resorcinol and 2,4-dinitrosoresorcinolKaraseva, E. I.; Losev, Yu. P.; Metelitsa, D. I.Russian Journal of Bioorganic Chemistry (Translation of Bioorganicheskaya Khimiya) (2002), 28 (2), 128-135CODEN: RJBCET; ISSN:1068-1620. (MAIK Nauka/Interperiodica Publishing)A comparative study of the kinetics of peroxidase-catalyzed oxidn. of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of 2,4-dinitrosoresorcinol (DNR), its polydisulfide deriv. [poly(DNRDS)], and resorcinol polydisulfide [poly(RDS)], substances that competitively inhibit the formation of TMB conversion product, was carried out. The inhibition consts. Ki for DNR, poly(DNRDS), and poly(RSD) were detd. at 20° and pH 6.4 to be 110, 13.5, and 0.78 μM, resp. The stoichiometric coeffs. of inhibition were calcd. to be 0.38 and 76 for poly(DNRDS) and poly(RDS), resp. In the pH range 6.4-7.0, the initial rates of the peroxidative oxidn. of TMB, and its mixts. with DNR and poly(DNRDS) and the Ki, value for poly(RDS) substantially decreased with increasing pH. The kinetic parameters of poly(RDS) (Ki 0.22-0.78 μM and f76) suggest that it is the most efficient inhibitor of peroxidase oxidn. of TMB: in micromolar concns., it completely stops this process and can be used in EIA.
- 62Lineweaver, H.; Burk, D. The determination of enzyme dissociation constants. J. Am. Chem. Soc. 1934, 56 (3), 658– 666, DOI: 10.1021/ja01318a03662https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaA2cXisF2ltg%253D%253D&md5=6bacac43540e56d2a3a3955b2911a12dDetermination of enzyme dissociation constantsLineweaver, Hans; Burk, DeanJournal of the American Chemical Society (1934), 56 (), 658-66CODEN: JACSAT; ISSN:0002-7863.Graphical methods involving const. slopes and straight-line extrapolations have been developed for testing and interpreting kinetic data and for detg. dissocn. consts. of enzyme-substrate and enzyme-inhibitor compds. and other related consts. when the data are found to be consistent with an assigned mechanism. Representative analyses are given for invertase, raffinase, amylase, citric dehydrogenase, catalase, oxygenase, esterase and lipase, involving substrate activation, substrate inhibition, general competitive and noncompetitive inhibition, steady states and reactions of various orders. The various methods described are applicable to gen. chem. catalysis, homogeneous or heterogeneous.
- 63Ma, Z.-Z.; Wang, Y.-S.; Liu, B.; Jiao, H.; Xu, L. A non–enzymatic electrochemical sensor of Cu@Co–MOF composite for glucose detection with high sensitivity and selectivity. Chemosensors 2022, 10 (10), 416, DOI: 10.3390/chemosensors1010041663https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XislGgur3M&md5=0c045dbc093894ae44d00c561ae7537cA Non-Enzymatic Electrochemical Sensor of Cu@Co-MOF Composite for Glucose Detection with High Sensitivity and SelectivityMa, Zhen-Zhen; Wang, Yue-Shu; Liu, Bing; Jiao, Huan; Xu, LingChemosensors (2022), 10 (10), 416CODEN: CHEMQ9; ISSN:2227-9040. (MDPI AG)A 3D cobalt metal-org. framework (Co-MOF), [Co3(BDC)3(DMU)2], was utilized to prep. Cu@Co-MOF composite in a deposition-redn. process. Cu@Co-MOF/GCE (GCE = glassy carbon electrode) electrode was prepd. by "drop-coating" method. Cu@Co-MOF/GCE shows excellent electrocatalytic activity for Glu detection. The chronoamperometric response of Cu@Co-MOF/GCE to Glu concn. (CGlu) displays linear relationships in two CGlu sections with calcd. sensitivities of 282.89 μA mM-1 cm-2 within 0.005-0.4 mM Glu and 113.15 μA mM-1 cm-2 within 0.4-1.8 mM Glu. The detection limit is calcd. as 1.6 μM at S/N = 3. Cu@Co-MOF/GCE also exhibits a rapid current response, high anti-interference, stability, and repeatability to Glu detection. Cu@Co-MOF/GCE was applied to detect Glu in human serum and orange juice. All found CGlu are very close to those added CGlu with low RSDs and high recoveries. Cu@Co-MOF/GCE as a non-enzymic electrochem. sensor of Glu has high sensitivity, selectivity, accuracy, and reliability.
- 64Altahan, M. F.; Esposito, M.; Bogner, B.; Achterberg, E. P. The Use of Bi-Potentiostat as a Simple and Accurate Electrochemical Approach for the Determination of Orthophosphate in Seawater. Sensors 2023, 23 (4), 2123, DOI: 10.3390/s2304212364https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXkt1Chtb0%253D&md5=9fa256d3706f1bddf2a1a20bca38cfd9The Use of Bi-Potentiostat as a Simple and Accurate Electrochemical Approach for the Determination of Orthophosphate in SeawaterAltahan, Mahmoud Fatehy; Esposito, Mario; Bogner, Boie; Achterberg, Eric P.Sensors (2023), 23 (4), 2123CODEN: SENSC9; ISSN:1424-8220. (MDPI AG)Autonomous on-site monitoring of orthophosphate (PO43-), an important nutrient for primary prodn. in natural waters, is urgently needed. Here, we report on the development and validation of an on-site autonomous electrochem. analyzer for PO43- in seawater. The approach is based on the use of flow injection anal. in conjunction with a dual electrochem. cell i.e., a bi-potentiostat detector (FIA-DECD) that uses two working electrodes sharing the same ref. and counter electrode. The two working electrodes are used (molybdate/carbon paste electrode (CPE) and CPE) to correct for matrix effects. Optimization of squarewave voltammetry parameters (including step potential, amplitude, and frequency) was undertaken to enhance anal. sensitivity. Possible interferences from non-ionic surfactants and humic acid were investigated. The limit of quantification in artificial seawater (30 g/L NaCl, pH 0.8) was 0.014μM for a linear concn. range of 0.02-3μM. The system used a Python script for operation and data processing. The analyzer was tested for ship-board PO43- detn. during a four-day research cruise in the North Sea. The analyzer successfully measured 34 samples and achieved a good correlation (Pearson' R = 0.91) with discretely collected water samples analyzed using a lab.-based colorimetric ref. analyzer.
- 65Pensa, E.; Cortés, E.; Corthey, G.; Carro, P.; Vericat, C.; Fonticelli, M. H.; Benitez, G.; Rubert, A. A.; Salvarezza, R. C. The chemistry of the sulfur–gold interface: in search of a unified model. Acc. Chem. Res. 2012, 45 (8), 1183– 1192, DOI: 10.1021/ar200260p65https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XksVKns78%253D&md5=02c8627b2ed34cd4c98cf51fd8dbfe91The Chemistry of the Sulfur-Gold Interface: In Search of a Unified ModelPensa, Evangelina; Cortes, Emiliano; Corthey, Gaston; Carro, Pilar; Vericat, Carolina; Fonticelli, Mariano H.; Benitez, Guillermo; Rubert, Aldo A.; Salvarezza, Roberto C.Accounts of Chemical Research (2012), 45 (8), 1183-1192CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)A review. Over the last three decades, self-assembled mol. films on solid surfaces have attracted widespread interest as an intellectual and technol. challenge to chemists, physicists, materials scientists, and biologists. A variety of technol. applications of nanotechnol. rely on the possibility of controlling topol., chem., and functional features at the mol. level. Self-assembled monolayers (SAMs) composed of chemisorbed species represent fundamental building blocks for creating complex structures by a bottom-up approach. These materials take advantage of the flexibility of org. and supramol. chem. to generate synthetic surfaces with well-defined chem. and phys. properties. These films already serve as structural or functional parts of sensors, biosensors, drug-delivery systems, mol. electronic devices, protecting capping for nanostructures, and coatings for corrosion protection and tribol. applications. Thiol SAMs on gold are the most popular mol. films because the resulting oxide-free, clean, flat surfaces can be easily modified both in the gas phase and in liq. media under ambient conditions. In particular, researchers have extensively studied SAMs on Au(111) because they serve as model systems to understand the basic aspects of the self-assembly of org. mols. on well-defined metal surfaces. Also, great interest has arisen in the surface structure of thiol-capped gold nanoparticles (AuNPs) because of simple synthesis methods that produce highly monodisperse particles with controllable size and a high surface/vol. ratio. These features make AuNPs very attractive for technol. applications in fields ranging from medicine to heterogeneous catalysis. In many applications, the structure and chem. of the sulfur-gold interface become crucial since they control the system properties. Therefore, many researchers have focused on understanding of the nature of this interface on both planar and nanoparticle thiol-covered surfaces. However, despite the considerable theor. and exptl. efforts made using various sophisticated techniques, the structure and chem. compn. of the sulfur-gold interface at the at. level remains elusive. In particular, the search for a unified model of the chem. of the S-Au interface illustrates the difficulty of detg. the surface chem. at the nanoscale. This Account provides a state-of-the-art anal. of this problem and raises some questions that deserve further investigation.
- 66Krüger, D.; Rousseau, R.; Fuchs, H.; Marx, D. Towards “mechanochemistry”: mechanically induced isomerizations of thiolate–gold clusters. Angew. Chem., Int. Ed. 2003, 42 (20), 2251– 2253, DOI: 10.1002/anie.200351000There is no corresponding record for this reference.
- 67Huang, Z.; Chen, F.; Bennett, P. A.; Tao, N. Single molecule junctions formed via Au– thiol contact: stability and breakdown mechanism. J. Am. Chem. Soc. 2007, 129, 13225– 13231, DOI: 10.1021/ja074456t67https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtFWgur3N&md5=223b6654a07c908a0546491e1bfb44e2Single Molecule Junctions Formed via Au-Thiol Contact: Stability and Breakdown MechanismHuang, Zhifeng; Chen, Fang; Bennett, Peter A.; Tao, NongjianJournal of the American Chemical Society (2007), 129 (43), 13225-13231CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)The stability and breakdown mechanism of a single mol. covalently bound to two Au electrodes via Au-S bonds were studied at room temp. The distance over which a mol. junction can be stretched before breakdown was measured using a scanning tunneling microscopy break junction approach as a function of stretching rate. At low stretching rates, the stretching distance is small and independent of stretching rate. Above a certain stretching rate, it increases linearly with the logarithm of stretching rate. At very high stretching rates, the stretching distance reaches another plateau and becomes insensitive to the stretching rate again. The three regimes are well described by a thermodn. bond-breaking model. A comparative study of Au-Au at. point contacts indicates that the breakdown of the mol. junctions takes place at Au-Au bonds near the mol.-electrode contact. By fitting the exptl. data with the model, the lifetime and binding energy were extd. Both quantities are found to have broad distributions, owing to large variations in the mol.-electrode contact geometry. Although the mol. junctions are short-lived on av., certain contact geometries are considerably more stable. Several types of stochastic fluctuations were obsd. in the conductance of the mol. junctions, which are attributed to the at. level rearrangement of the contact geometry, and bond breakdown and reformation processes. The possibility of bond reformation increases the apparent lifetime of the mol. junctions.
- 68Wang, W.; Rusin, O.; Xu, X.; Kim, K. K.; Escobedo, J. O.; Fakayode, S. O.; Fletcher, K. A.; Lowry, M.; Schowalter, C. M.; Lawrence, C. M. Detection of homocysteine and cysteine. J. Am. Chem. Soc. 2005, 127 (45), 15949– 15958, DOI: 10.1021/ja054962n68https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtFalu7rP&md5=c572a5b02956af7dbc6b4fb551651fc0Detection of Homocysteine and CysteineWang, Weihua; Rusin, Oleksandr; Xu, Xiangyang; Kim, Kyu Kwang; Escobedo, Jorge O.; Fakayode, Sayo O.; Fletcher, Kristin A.; Lowry, Mark; Schowalter, Corin M.; Lawrence, Candace M.; Fronczek, Frank R.; Warner, Isiah M.; Strongin, Robert M.Journal of the American Chemical Society (2005), 127 (45), 15949-15958CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)At elevated levels, homocysteine (Hcy) is a risk factor for cardiovascular diseases, Alzheimer's disease, neural tube defects, and osteoporosis. Both Hcy and cysteine (Cys) are linked to neurotoxicity. The biochem. mechanisms by which Hcy and Cys are involved in disease states are relatively unclear. Herein, the authors describe simple methods for detecting either Hcy or Cys in the visible spectral region with the highest selectivity reported to date without using biochem. techniques or preparative sepns. Simple methods and readily available reagents allow for the detection of Cys and Hcy in the range of their physiol. relevant levels. New HPLC postcolumn detection methods for biol. thiols are reported. The potential biomedical relevance of the chem. mechanisms involved in the detection of Hcy is described.
- 69Han, H.; Wang, F.; Chen, J.; Li, X.; Fu, G.; Zhou, J.; Zhou, D.; Wu, W.; Chen, H. Changes in biothiol levels are closely associated with alzheimer’s disease. J. Alzheimer’s Dis. 2021, 82 (2), 527– 540, DOI: 10.3233/JAD-21002169https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhs1Wnt7zM&md5=ba2df8941bd7722a558c37f2e47f3973Changes in Biothiol Levels Are Closely Associated with Alzheimer's DiseaseHan, Hui; Wang, Feng; Chen, Juanjuan; Li, Xingxing; Fu, Gaoqing; Zhou, Jiawei; Zhou, Dongsheng; Wu, Wei; Chen, HaiminJournal of Alzheimer's Disease (2021), 82 (2), 527-540CODEN: JADIF9; ISSN:1387-2877. (IOS Press)Serum homocysteine (Hcy) level is considered to be an important biomarker for Alzheimer's disease (AD); however, the status of Hcy in brain tissue, and the assocn. between brain and serum levels of Hcy in AD patients remain unclear. We aimed to examine whether the changes of three thiols are consistent in serum of AD patients and the brain of APP/PS1 mice, and to verify the effectiveness of Hcy as a biomarker for early AD detection. The levels of Hcy, cysteine (Cys), and glutathione (GSH) in Aβ1-42-treated PC12 cells, the brain and hippocampus of APP/PS1 mouse, and the serum of AD patients were evaluated using Et (E)-3-(9-chloro-11-oxo-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f] pyrido [3,2,1 -ij] quinolin-10-yl)-2-cyanoacrylate (Probe 1) and ELISA assay or LC-MS. Measurement by Probe 1 revealed a significant increase in Hcy level, and a decrease in Cys and GSH levels in Aβ1-42-treated PC12 cells and the serum of AD patients. The hippocampus and whole brain of APP/PS1 mice also showed a significant increase in Hcy level alongside the accumulation of age-related AD symptoms. The upregulation of Hcy and the downregulation of Cys and GSH were reversed in the Aβ1-42-treated PC12 cells and the brain of APP/PS1 mice when supplemented with VB6. Changes in Hcy, Cys, and GSH levels in the brain of APP/PS1 mice and Aβ1-42-treated PC12 cells were obsd. in situ with a new fluorescent probe, which were consistent with the abnormal changes in Hcy, Cys, and GSH levels in the serum of AD patients. VB6 supplementation was successful in ameliorating abnormal increases in Hcy levels.
- 70Chen, Z.; Sun, Q.; Yao, Y.; Fan, X.; Zhang, W.; Qian, J. Highly sensitive detection of cysteine over glutathione and homo-cysteine: new insight into the Michael addition of mercapto group to maleimide. Biosens. Bioelectron. 2017, 91, 553– 559, DOI: 10.1016/j.bios.2017.01.01370https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFOgsb8%253D&md5=b6653d320033dce5eb67b7604d66473dHighly sensitive detection of cysteine over glutathione and homo-cysteine: New insight into the Michael addition of mercapto group to maleimideChen, Zhaoyang; Sun, Qian; Yao, Yuhua; Fan, Xiaoxiang; Zhang, Weibing; Qian, JunhongBiosensors & Bioelectronics (2017), 91 (), 553-559CODEN: BBIOE4; ISSN:0956-5663. (Elsevier B.V.)A fluorescence "off-on" probe CMP for thiols was designed with coumarin as the fluorophore and maleimide as the receptor. The fluorescence of the coumarin was quenched through photoinduced electron transfer (PET) from the fluorophore to maleimide group. The Michael addn. of the mercapto group toward maleimide formed a thioether with relatively weak fluorescence. The intramol. nucleophilic substitution of amino group in cysteine (Cys) to alkylthio produced a much stronger fluorescent amino adduct, which was supported by UPLC-MS and NMR titrn. The above sensing mechanism ensured CMP a highly sensitive probe toward Cys over GSH and Hcy. The fluorescence intensity at 495 nm was linear with Cys concn. over the range of 0-10μM with a detection limit of 14 nM and a rapid response time of 20 min. High selectivity and good competition of the probe toward thiols over other biol. relevant species enabled us to monitor mercapto-contg. proteins as well as fluorescence imaging Cys in living cells.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsanm.3c05677.
DLS data for pSi and different AuNP-pSi nanohybrids, UV–vis absorbance of pSi and different AuNP-pSi nanohybrids, XRD for pSi and AuNP-pSi nanohybrids, digital photographs of TMB catalyzed by AuNP-pSi nanohybrids, additional details for mechanism of AuNP formation and their catalytic activity, assessment of glucose oxidase activity of AuNP-pSi, comparison of AuNP-pSi with other nanozymes, natural peroxidase, and comparison of biothiol detection performance of AuNP-pSi nanohybrids with standard methods (PDF)
Description of supplementary video: a stepwise on-demand activation of AuNP-pSi peroxidase-mimicking nanozyme and their ability to oxidize TMB in the presence of H2O2 (MP4)
Terms & Conditions
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.
