Immunotoxic and oxidative stress potential of copper oxide and platinum nanoparticles on aquatic organisms

Abstract

The rapid increase in the use and production of copper oxide and platinum nanoparticles (NPs) in several areas contributes to presence of these contaminants in aquatic ecosystems. Some studies have reported the toxicity of NPs to aquatic organisms, but the investigation of its toxic potential in the immune system of these species is limited. Considering the small size of NPs (<100 nm), one may expect that the immune system and the antioxidant defenses of organisms react to presence of NPs and cause ecological imbalances in populations. This proposal aims to evaluate the immunotoxic and oxidative stress potential of copper oxide and platinum NPs to the cladoceran Daphnia magna and the fish Danio rerio. Tests to determine the toxicity of NPs to test organisms will be carried out. Then, the species will be exposed to sublethal concentrations of NPs to evaluate the immunotoxic and oxidative stress effects using biomarkers. Oxidative stress will be analyzed by determining the reactive oxygen species levels, the antioxidant enzymes activity and the malondialdehyde concentration in cladocera and fish tissues. Immune response of D. magna to NPs will be evaluated by determining the hemocytes number and the phenoloxidase activity. Immunotoxic effects of NPs to D. rerio will be determined by the leukocytes number, the IgM concentration and the lysozyme activity in blood samples. Neutrophil function of kidneys of the fish will also be evaluated. This research will elucidate the main mechanisms responsible for the deleterious effects of NPs on cladocerans and fishes, besides providing information that will subsidize regulatory actions to improve the protection of aquatic biota.