Enhanced Oxidative Stress and Physiological Damage in <i>Daphnia magna</i> by Copper in the Presence of Nano‐TiO₂

Abstract

This study examines the potential hazard of an individual nanomaterial on the Cu biotoxicity to aquatic organisms. Daphnia magna in the absence or presence of nano‐TiO 2 was exposed to Cu. Maintaining nano‐TiO 2 at a safe concentration cannot eliminate its potential hazard. The biomarkers superoxide dismutase, catalase, and Na + /K + ‐ATPase in D. magna were measured. Cu in the presence of nano‐TiO 2 induced higher levels of oxidative stress and physiological damage because of the sorption of Cu. Nano‐TiO 2 also caused Na + /K + ‐ATPase inhibition possibly by impeding the Na + /K + transfer channel. The correlations among the biomarkers, mortality, and accumulation further showed that the overloading reactive oxygen species generation caused by nano‐TiO 2 contributed to deeper oxidative stress and physiological regulation, thereby causing greater toxic injury.