s What do we Really Know about Nanotoxicology of Silver Nanoparticles In vivo? New Aspects, Possible Mechanisms, and Perspectives

Actually, many discussions on the potential risks of silver nanoparticles (AgNPs) have been reported; however, unfortunately, very few considered the great differences between the nature of silver and sources of their syntheses. All data suggested that the effects on toxicity of AgNPs are related to the combination of the specific properties of AgNPs. In this context, this review presents and discusses the recent progress in the nanotoxicity of AgNPs, obtained by different biogenic synthetic protocols, in comparison with chemical synthetic methods, driving to the formation of nanoparticles with diverse structures, and size distributions. Biogenic syntheses of AgNPs using several biological sources and other chemical agents are presented and discussed. Toxicity in different animals is also presented and discussed. By considering the actual state of the art, it can be assumed that oral, intravenous and inhalation doses of AgNPs from 0.1 to 2 mg/Kg in mice and rats are considered a safe administration. In terms of ecotoxicity, it is more concerning since many of the in vivo assays showed a very low lethal dose, i.e., 50% (LD50). Therefore, we have to be very careful with the AgNPs residues in the environment.