Nanosilver and Silver Nitrate Toxicity in Ex Vivo-Exposed Gills of Fish and Mitigation by Humic Acids

Abstract

Silver nanoparticles (AgNP) are unique because of their biocide properties. Once released to environment, AgNP interact with the natural organic matter which impact on their fate, dispersion, and ultimate toxicity. We carried out an ex vivo exposure of gill of Corydoras paleatus fish to 100 μg L−1 of AgNP or AgNO3, alone and in combination with 10 mg L−1 of humic acids (HA), with the aim to evaluate the potential mitigation of HA on AgNP toxic effects. We analyzed Ag accumulationand oxidative stress biomarkers. The results showed high bioaccumulation after the AgNO3+ HA exposure. An inhibition of glutathione-S-transferase enzymatic activity and depletion of reduced glutathione levels were registered after the AgNO3 exposure, and increased lipid peroxidation levels in the case of AgNP one. Oxidative responses were mitigated when the HA were present in the media. Overall, the knowledge about the fate of this emergent pollutant was deepened through this study.