Blood biochemical changes in common carp (Cyprinus carpio) upon co-exposure to titanium dioxide nanoparticles and paraquat

Research on eliminating organic pollutants in water by using heterogeneous photocatalysts such as nano-TiO2 abound. However, the question is whether metabolites, resulting from optical dispersion of environmental pollutants, are still toxic to aquatic organisms. Therefore, this study was designed to evaluate the effect of a co-exposure to paraquat and TiO2-NPs on blood biochemical indices of common carp. Fish were exposed to 0.2 and 0.4 mg L-1 paraquat with 0.125 mg L-1 TiO2-NPs for 21 days under different light conditions, including natural photoperiod (16 L 8h-1 D) and complete darkness. No significant alterations in the Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Lactate dehydrogenase (LDH), Alkaline phosphatase (ALP) and Creatine phosphokinase (CPK), activities and total protein, albumin, globulin, glucose, cholesterol and triglyceride levels were observed in fish exposed to TiO2-NPs and 0.2 mg L-1 paraquat under normal lighting conditions. However, a significant change in blood biochemical indices in fish exposed to TiO2-NPs with 0.4 mg L-1 paraquat (16 L 8h-1 D) and in fish exposed to TiO2-NPs and paraquat (under darkness). A significant decrease in the activity of Gamma-glutamyltransferase (GGT) and a significant increase in creatinine level were observed in all groups which were exposed to TiO2-NPs and paraquat. The results of this study indicate that using 0.125 mg L-1 nano-TiO2 in order to remove paraquat (0.2 mg L-1) under lighting conditions can minimize the adverse effects of paraquat and its metabolites on blood biochemical indices of fish. So, using nano-TiO2 (0.125 mg L-1) to remove paraquat under lighting conditions can significantly reduce its toxic effects.