Emerging Methods Section, Aquatic Contaminants Research Division, Water Science and Technology Directorate, Environment Canada, Montréal, Quebec, Canada.
J Toxicol Environ Health A. 2013;76(8):479-90. doi: 10.1080/15287394.2013.779561.
The increasing application of silver nanoparticles (nAg) in various consumer products has raised concerns regarding toxicological impacts in the environment. It is unclear at present whether the toxicity of nAg is mainly the result of the release of ionic Ag(+) in mussels. The freshwater mussel Elliptio complanata was exposed to increasing concentrations of 20-nm nAg, 80-nm nAg, and dissolved Ag(+) for 48 h at 15°C. The following biomarkers were used to determine the mode of action of nAg-induced adverse effects: metallothioneins (MT) (ionic Ag(+) release), lipid peroxidation (LPO) (ionic Ag(+) and nanosurface interactions), heat-shock proteins (HSP) (size-related effects), protein-ubiquitin levels (size-related effects), and DNA strand breaks (ionic Ag(+) and size effects). Results revealed that the response pattern of 80 nm nAg was more closely related to ionic Ag(+) than 20 nm nAg, suggesting a more important release of dissolved Ag from 80 nm nAg. Data showed that all forms of Ag were able to increase the levels of MT and LPO, which suggests the presence of ionic Ag(+) leads to oxidative stress. However, nanoparticles were also able to induce changes in protein-ubiquitin and to a lesser extent actinomyosin-ATPase, MT, and DNA strand breaks in the digestive gland in a manner different from Ag(+), which permitted discrimination of the forms of Ag. Moreover, LPO was closely associated with DNA strand breaks in the digestive gland and was not entirely explained by induction of MT, suggesting another type of toxic interaction. It was concluded that the presence of nAg not only increases the toxic loadings of released Ag ions but also generates other and perhaps cumulative effects of nanoparticle-induced toxicity related to size and surface properties.
纳米银（nAg）在各种消费品中的应用日益广泛，这引起了人们对环境中毒理学影响的关注。目前尚不清楚 nAg 的毒性是否主要是由于贝类中离子 Ag(+)的释放所致。淡水贻贝 Elliptio complanata 在 15°C 下，经 48 小时暴露于浓度不断增加的 20nm nAg、80nm nAg 和溶解态 Ag(+)中。采用以下生物标志物来确定 nAg 诱导的不良反应的作用模式：金属硫蛋白（MT）（离子 Ag(+)释放）、脂质过氧化（LPO）（离子 Ag(+)和纳米表面相互作用）、热休克蛋白（HSP）（尺寸相关效应）、蛋白-泛素水平（尺寸相关效应）和 DNA 链断裂（离子 Ag(+)和尺寸效应）。结果表明，80nm nAg 的反应模式与离子 Ag(+)的关系比 20nm nAg 更为密切，这表明 80nm nAg 中溶解态 Ag 的释放更为重要。数据表明，所有形式的 Ag 都能够增加 MT 和 LPO 的水平，这表明存在离子 Ag(+)会导致氧化应激。然而，纳米颗粒也能够以不同于 Ag(+)的方式诱导蛋白-泛素发生变化，并在较小程度上诱导肌动球蛋白-ATP 酶、MT 和 DNA 链断裂，从而区分不同形式的 Ag。此外，LPO 与消化腺中的 DNA 链断裂密切相关，不能完全用 MT 的诱导来解释，这表明存在另一种有毒相互作用。结论是，nAg 的存在不仅增加了释放的离子 Ag 负载，而且还产生了与尺寸和表面特性相关的其他纳米颗粒诱导毒性的累积效应。
