Multiple biomarker responses in earthworms exposed to copper oxide nanoparticles

Aim and Background: The nanotechnology industry is playing an increasingly important role in the global economy. In recent years, copper-based nanoparticles are increasingly used in various fields. Increased applications of nanoparticles augment the possibility of their deposition into soil ecosystems and threatening the terrestrial life. Since oxidative stress (OS) is a common mechanism for nanoparticle-induced cell damages, we aimed to evaluate the toxicity of copper oxide nanoparticles (n-CuO) on OS biomarkers in earthworms. Methods: According to OECD guidelines, earthworms were exposed to 40 nm n-CuO at nominal concentrations (2.5, 5 10 mg/kg dry soil) in natural soil samples for 21 days, and then recovered for 28 days. The OS biomarkers namely lipoperoxidation (LPO/MDA), catalase (CAT), carbonylated proteins (CP), cellulase (a gut enzyme), and total antioxidant capacity (TAC) levels in homogenates, along with histopathological examinations were evaluated. Results and discussion: Upon n-CuO exposure, the LPO and CP contents were found to be increased significantly. Also, CAT and cellulase activities, and TAC value were lowered markedly (p 0.05) in response to n-CuO exposure. Meanwhile, tissue damages were observed in the earthworm’s body wall. After recovery, only CAT and cellulase activities returned to normal level. Conclusion: n-CuO exerted toxic potential in earthworms by inducing oxidative stress. These changes may affect earthworm’s compatibility with soil environment. Our study provides valuable insights for elucidating the effect of n-CuO on earthworms as valuable organisms in soil quality.