Protective Effects of Selenium Against TiZn Nanocomposite‐Induced Oxidative Stress and Neurotoxicity in the Freshwater Mussel <scp> <i>Unio ravoisieri</i> </scp>

The increasing production and application of engineered nanoparticles have raised significant environmental and health concerns, particularly, regarding their potential release into aquatic ecosystems. Among these, multifunctional nanocomposites combining titanium dioxide (TiO₂) and zinc oxide (ZnO) have garnered considerable attention due to their widespread use. This study examined the biological responses of the freshwater mussel Unio ravoisieri to TiZn nanocomposites at concentrations of 10 and 100 μg/L. In a subsequent phase, the potential protective effects of selenium (Se) against nanocomposite-induced toxicity were assessed using biochemical markers, including hydrogen peroxide (H₂O₂), catalase (CAT), reduced glutathione (GSH), glutathione-S-transferase (GST), malondialdehyde (MDA) levels, and acetylcholinesterase (AChE) activity. The results demonstrated that exposure to TiZn nanocomposites alone induced oxidative stress in the digestive gland, with elevated levels of CAT, GST, AChE, GSH, and MDA in a concentration-dependent manner. However, selenium co-administration at 100 μg/L significantly mitigated these oxidative responses, highlighting its potential as a protective agent against nanocomposite-induced toxicity. These findings suggest promising avenues for the use of selenium in reducing nanoparticle-related environmental stress in aquatic organisms.