Center for the Environmental Implications of Nanotechnology, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
Environ Sci Technol. 2012 Nov 20;46(22):12687-96. doi: 10.1021/es301521p. Epub 2012 Nov 12.
Motivated by the need to understand environmental risks posed by potentially biocidal engineered nanoparticles, the effects of silver nanoparticle (AgNP) exposure on viability in single species Pseudomonas fluorescens biofilms were determined via dye staining methods. AgNP dispersions, containing both particles and dissolved silver originating from the particles, negatively impacted biofilm viability in a dose-dependent manner. No silver treatments (up to 100 ppm AgNPs) resulted in 100% biofilm viability loss, even though these same concentrations caused complete viability loss in planktonic culture, suggesting some biofilm tolerance to AgNP toxicity. Colloidally stable AgNP suspensions exhibited greater toxicity to biofilms than corresponding particle-free supernatants containing only dissolved silver released from the particles. This distinct nanoparticle-specific toxicity was not observed for less stable, highly aggregated particles, suggesting that biofilms were protected against nanoparticle aggregate toxicity. In both the stable and highly aggregated dispersions, dissolved silver made a significant contribution to overall toxicity. Therefore, despite increased colloidal stability when humic acid adsorbed to AgNPs, the presence of humic acid mitigated the toxicity of AgNP suspensions because it bound to silver ions in solution.
为了了解潜在的具有杀菌作用的工程纳米粒子所带来的环境风险，本研究通过染色法确定了银纳米粒子（AgNP）暴露对单一物种荧光假单胞菌生物膜活力的影响。AgNP 分散体既包含颗粒，又包含源自颗粒的溶解银，以剂量依赖的方式对生物膜活力产生负面影响。即使在浮游培养物中相同浓度会导致完全丧失活力，也没有任何银处理（高达 100ppm 的 AgNPs）导致 100%的生物膜活力丧失，这表明生物膜对 AgNP 毒性具有一定的耐受性。胶体稳定的 AgNP 悬浮液对生物膜的毒性大于仅含有从颗粒中释放的溶解银的相应无颗粒上清液。对于不太稳定、高度聚集的颗粒，没有观察到这种明显的纳米颗粒特异性毒性，这表明生物膜能够抵御纳米颗粒聚集毒性。在稳定和高度聚集的分散体中，溶解银对整体毒性有很大贡献。因此，尽管当腐殖酸吸附到 AgNPs 时增加了胶体稳定性，但腐殖酸的存在减轻了 AgNP 悬浮液的毒性，因为它与溶液中的银离子结合。
