Effects of Au/TiO2 metallic nanoparticles on Unio ravoisieri: assessment through an oxidative stress and toxicity biomarkers.

Several studies have been performed on the effects of nanoparticles on aquatic life. However, most of them investigated marine organisms, not freshwater organisms. This study investigated biomarker responses after exposure for 48 h and 7 days to newly made gold and titanium dioxide (Au/TiO2) metallic nanoparticles (MNPs) (100 and 200 μg·L-1) using the freshwater bivalve mussel Unio ravoisieri. Biochemical analysis of the gills and digestive glands showed induction of oxidative stress following exposure of the bivalve to Au/TiO2 MNPs. After 2 or 7 days of exposure to Au/TiO2 MNPs, both utilized concentrations of Au/TiO2 MNPs induce an overproduction of H2O2. Catalase and glutathione S-transferase activities and the malonedialdehyde content significantly increased in the presence of Au/TiO2 MNPs, depending on the concentration and target organ. In contrast, acetylcholinesterase activity was significantly inhibited, indicating a discernible disturbance of the cholinergic system in the presence of Au/TiO2 MNPs. The behavior of the freshwater mussel was altered by reducing the clearance rate. Therefore, U. ravoisieri can be used as a model species in laboratory studies to mirror the presence of MNPs, and the biomarker approach is important for detecting the effects of Au/TiO2 MNPs. In addition, digestive gland is the target organ of Au/TiO2NPs contamination.