Toxicity of synthesized silver nanoparticles in a widespread fish: A comparison between green and chemical

Metallic nanoparticles are gaining importance in various fields of life due to their large surface area to volume ratio. However, metallic nanoparticles pose different toxic effects on fish when they appear with different shapes and compositions in water. Herein the present study was designed to evaluate the median (LC₅₀) and sub-lethal (1/10th of LC₅₀) concentrations of Ag-Green NPs, 700 μg/L for Ag-Chem NPs, and 50 μg/L for Ag₂O-Chem NPs were confirmed in Hypophthalmichthys molitrix. Furthermore, exposure of H. molitrix fingerlings to 10 % of LC₅₀ concentration of these particles induced significantly higher (p < 0.05) activities of serum alanine transaminase, aspartate aminotransferase, lactate dehydrogenase, white blood cells, acetylcholinesterase and catalase, superoxide dismutase, peroxidase, relative gene expressions of antioxidant enzymes, heat shock protein (Hsp70), hypoxia- inducible factor 1-alpha (HIF-1α) and lipid peroxidase level than the control, but decreased hematological parameters with less effects of Ag-Green NPs than chemically synthesized AgNPs. Moreover, the histopathological study also indicated morphological changes in the liver and gills of treated fish groups. The comparative toxicity evaluation revealed the maximum negative effect of Ag₂O-Chem NPs followed by Ag-Chem NPs while Ag-Green NPs showed the least toxic effects. Based on our results, replacement of chemically synthesized NPs to green synthesized AgNPs can be recommended in large scale application to reduce the noxious effects to aquatic environment.