Nanosilver (Ag NPs) is currently one of the most commercialized antimicrobial nanoparticles with as yet, still unresolved cytotoxicity origins. To date, research efforts have mostly described the antimicrobial contribution from the leaching of soluble silver, while the undissolved solid Ag particulates are often considered as being microbiologically inert, serving only as source of the cytotoxic Ag ions. Here, we show the rapid stimulation of lethal cellular oxidative stress in bacteria by the presence of the undissolved Ag particulates. The cytotoxicity characteristics are distinct from those arising from the leached soluble Ag, the latter being locked in organic complexes. The work also highlights the unique oxidative stress-independent bacterial toxicity of silver salt. Taken together, the findings advocate that future enquiries on the antimicrobial potency and also importantly, the environmental and clinical impact of Ag NPs use, should pay attention to the potential bacterial toxicological responses to the undissolved Ag particulates, rather than just to the leaching of soluble silver. The findings also put into question the common use of silver salt as model material for evaluating bacterial toxicity of Ag NPs.

中文翻译：

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纳米银和固体微粒相对于浸出的可溶性银的微生物活性

纳米银（Ag NPs）目前是最商业化的抗菌纳米颗粒之一，至今仍未解决细胞毒性。迄今为止，研究工作主要描述了可溶性银的浸出产生的抗微生物作用，而未溶解的固体银颗粒通常被认为具有微生物惰性，仅作为细胞毒性银离子的来源。在这里，我们显示了由于未溶解的银颗粒的存在而对细菌中致命的细胞氧化应激的快速刺激。细胞毒性特征不同于浸出的可溶性银，后者被锁定在有机复合物中。这项工作还强调了银盐独特的与氧化应激无关的细菌毒性。在一起 研究结果表明，关于抗菌效力的进一步询问以及重要的是，使用银纳米颗粒的环境和临床影响，应注意对未溶解的银颗粒的潜在细菌毒理学反应，而不仅仅是对可溶性银的浸出。这些发现还对银盐作为模型材料评估Ag NPs的细菌毒性提出了质疑。