Abstract
Silver, ZnO and CuO nanoparticles (NPs) are increasingly used as biocides. There is however increasing evidence of their threat to “non-target” organisms. In such a context, the understanding of the toxicity mechanisms is crucial for both the design of more efficient nano-antimicrobials, i.e. for “toxic by design” and at the same time for the design of nanomaterials that are biologically and/or environmentally benign throughout their life-cycle (safe by design). This review provides a comprehensive and critical literature overview on Ag, ZnO and CuO NPs’ toxicity mechanisms on the basis of various environmentally relevant test species and mammalian cells in vitro. In addition, factors modifying the toxic effect of nanoparticles, e.g. impact of the test media, are discussed. Literature analysis revealed three major phenomena driving the toxicity of these nanoparticles: (i) dissolution of nanoparticles, (ii) organism-dependent cellular uptake of NPs and (iii) induction of oxidative stress and consequent cellular damages. The emerging information on quantitative structure–activity relationship modeling of nanomaterials’ toxic effects and the challenges of extrapolation of laboratory results to the environment are also addressed.
Acknowledgements
MM, VS and AK thank the Scientific Exchange Program NMS-CH. This research was supported by the Estonian target funding project SF0690063s08, ETF8561, ETF9001, ETF9347, EU 7th Framework Program under grant agreement no. 263147 (NanoValid) and No. 309314 (MODERN). The study was supported by the EU Regional Development Foundation, Environmental Conservation and Environmental Technology R&D Program project TERIKVANT (3.2.0802.11-0043). VS acknowledges the support of the Swiss National Research Program 64 on the Opportunities and Risk of Nanomaterials.
Declaration of interest
The authors report no conflicts of interest and are responsible for the content and writing of the article.