Sublethal Effects of Biogenic Silver Nanoparticles and Silver Nitrate in the Neotropical Fish Prochilodus lineatus: Is the Nanoform Really Less Toxic?

摘要

Biogenic silver nanoparticles (bNAg) have been suggested as a less toxic alternative to ionic silver (Ag), and also a more ecological alternative to synthetic silver nanoparticles (sNAg). However, the differences between the sublethal effects caused by bNAg and silver nitrate (AgNO3) are hardly known, especially in native fishes of the Neotropical region. Most researchers have only compared the effects of sNAg and AgNO3. Thus, the objective of this work was to evaluate the effects of bNAg, produced by the fungus Fusarium oxysporum, and to compare these with the effects of AgNO3 in the Neotropical fish Prochilodus lineatus. The animals were exposed for 24 and 96 h at nominal concentrations of 10 and 25 mu g L-1 of Ag. At the end of the exposures, Ag accumulation, metallothionein concentration, hematological parameters, plasma glucose and ion concentrations, activity of the main ATPases and carbonic anhydrase in the gills, enzymatic and non-enzymatic antioxidants, lipid peroxidation, and neurotoxic effects were evaluated. Both bNAg and AgNO3 caused Ag accumulation in the blood, gills, and brain, in addition to neurotoxic effects on muscle, alterations in reduced glutathione concentration in the gills, and increased glutathione-S-transferase activity in the liver. Hyperglycemia, ionic imbalances, and alterations in the activity of ion transport enzymes in the gills were also observed. As the effects of bNAg were similar to the effects of AgNO3, it is concluded that animals exposed to the highest concentration of silver were the most affected, regardless of the form of silver used in the exposure medium.