Chemical Transformations of Nanosilver in Biological Environments
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- 作者：Jingyu Liu ; Zhongying Wang ; Frances D. Liu ; Agnes B. Kane ; Robert H. Hurt
- 刊名：ACS Nano
- 出版年：2012
- 出版时间：November 27, 2012
- 年：2012
- 卷：6
- 期：11
- 页码：9887-9899
- 全文大小：745K
- 年卷期：v.6,no.11(November 27, 2012)
- ISSN：1936-086X
文摘
The widespread use of silver nanoparticles (Ag-NPs) in consumer and medical products provides strong motivation for a careful assessment of their environmental and human health risks. Recent studies have shown that Ag-NPs released to the natural environment undergo profound chemical transformations that can affect silver bioavailability, toxicity, and risk. Less is known about Ag-NP chemical transformations in biological systems, though the medical literature clearly reports that chronic silver ingestion produces argyrial deposits consisting of silver-, sulfur-, and selenium-containing particulate phases. Here we show that Ag-NPs undergo a rich set of biochemical transformations, including accelerated oxidative dissolution in gastric acid, thiol binding and exchange, photoreduction of thiol- or protein-bound silver to secondary zerovalent Ag-NPs, and rapid reactions between silver surfaces and reduced selenium species. Selenide is also observed to rapidly exchange with sulfide in preformed Agb>2 b>S solid phases. The combined results allow us to propose a conceptual model for Ag-NP transformation pathways in the human body. In this model, argyrial silver deposits are not translocated engineered Ag-NPs, but rather secondary particles formed by partial dissolution in the GI tract followed by ion uptake, systemic circulation as organo-Ag complexes, and immobilization as zerovalent Ag-NPs by photoreduction in light-affected skin regions. The secondary Ag-NPs then undergo detoxifying transformations into sulfides and further into selenides or Se/S mixed phases through exchange reactions. The formation of secondary particles in biological environments implies that Ag-NPs are not only a product of industrial nanotechnology but also have long been present in the human body following exposure to more traditional chemical forms of silver.<br>