Department of Chemistry and Open Laboratory of Chemical Biology of the Institute of Technology for Drug Discovery and Synthesis, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Chem Asian J. 2010 Feb 1;5(2):285-93. doi: 10.1002/asia.200900387.
The oxidative dissolution of silver nanoparticles (AgNPs) plays an important role in the synthesis of well-defined nanostructured materials, and may be responsible for their activities in biological systems. In this study, we use stopped-flow spectrophotometry to investigate the kinetics and mechanism of the oxidative dissolution of AgNPs by H(2)O(2) in quasi-physiological conditions. Our results show that the reaction is first order with respect to both [Ag(0)] and [H(2)O(2)], and parallel pathways that involve the oxidation of H(2)O(2) and HO(2)(-) are proposed. The order of the reaction is independent of the size of the AgNPs (approximately 5-20 nm). The rate of dissolution increases with increasing pH from 6.0 to 8.5. At 298 K and I=0.1 M, the value of k(b) is five orders of magnitude higher than that of k(a) (where k(a) and k(b) are the rate constants for the oxidative dissolution of AgNPs by H(2)O(2) and HO(2)(-), respectively). In addition, the effects of surface coating and the presence of halide ions on the dissolution rates are investigated. A possible mechanism for the oxidative dissolution of AgNPs by H(2)O(2) is proposed. We further demonstrate that the toxicities of AgNPs in both bacteria and mammalian cells are enhanced in the presence of H(2)O(2), thereby highlighting the biological relevance of investigating the oxidative dissolution of AgNPs.
银纳米粒子（AgNPs）的氧化溶解在定义明确的纳米结构材料的合成中起着重要作用，并且可能是它们在生物系统中活性的原因。在这项研究中，我们使用停流分光光度法在准生理条件下研究了 H(2)O(2)氧化溶解 AgNPs 的动力学和机制。我们的结果表明，该反应对[Ag(0)]和[H(2)O(2)]均为一级反应，并提出了涉及 H(2)O(2)和 HO(2)(-)氧化的平行途径。反应的顺序与 AgNPs 的大小无关（约 5-20nm）。溶解速率随 pH 值从 6.0 增加到 8.5 而增加。在 298 K 和 I=0.1 M 下，k(b)的值比 k(a)高五个数量级（其中 k(a)和 k(b)分别是 AgNPs 被 H(2)O(2)和 HO(2)(-)氧化溶解的速率常数）。此外，还研究了表面涂层和卤化物离子的存在对溶解速率的影响。提出了 H(2)O(2)氧化溶解 AgNPs 的可能机制。我们进一步证明，在 H(2)O(2)存在下，AgNPs 在细菌和哺乳动物细胞中的毒性增强，从而突出了研究 AgNPs 氧化溶解的生物学相关性。
