Chemical transformations of nanosilver in biological environments.
Chemical transformations of nanosilver in biological environments.
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DOI：
10.1021/nn303449n
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发表时间：
2012-11-27
期刊：
影响因子：
17.1
通讯作者：
Hurt, Robert H.
中科院分区：
文献类型：
--
作者：
Liu, Jingyu;Wang, Zhongying;Liu, Frances D.;Kane, Agnes B.;Hurt, Robert H.
纳米银粒子（Ag - NPs）在消费品和医疗产品中的广泛使用，为仔细评估其环境和人类健康风险提供了强大动力。近期研究表明，释放到自然环境中的纳米银粒子会发生深刻的化学转化，这会影响银的生物可利用性、毒性和风险。尽管医学文献明确报道长期摄入银会产生由含银、硫和硒的颗粒相组成的银质沉着物，但对于生物系统中纳米银粒子的化学转化了解较少。在此我们表明，纳米银粒子会经历一系列丰富的生化转化，包括在胃酸中加速氧化溶解、巯基结合与交换、巯基或蛋白质结合的银光还原为次生零价纳米银粒子，以及银表面与还原态硒物质之间的快速反应。还观察到硒化物在预先形成的硫化银（Ag₂S）固相中与硫化物快速交换。综合这些结果使我们能够提出一个关于纳米银粒子在人体内转化途径的概念模型。在该模型中，银质沉着物中的银不是迁移的人工纳米银粒子，而是由在胃肠道中部分溶解，随后离子吸收，以有机银复合物形式全身循环，并在受光影响的皮肤区域通过光还原固定为零价纳米银粒子而形成的次生粒子。然后次生纳米银粒子经过解毒转化为硫化物，并通过交换反应进一步转化为硒化物或硒/硫混合相。生物环境中次生粒子的形成意味着纳米银粒子不仅是工业纳米技术的产物，而且在人体接触更传统的银化学形式之后就长期存在于人体内。
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 zero-valent Ag-NPs, and rapid reactions between silver surfaces and reduced selenium species. Selenide is also observed to rapidly exchange with sulfide in preformed Ag2S 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 zero-valent 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 have long been present in the human body following exposure to more traditional chemical forms of silver.
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