Are CuO nanoparticles effects on hemocytes of the marine scallop (Chlamys farreri) caused by particles and/or corresponding released ions?

Manufactured nanoparticles (NPs) have become emerging pollutants and attracted extensive concern about their potential effects on the marine environment. However, the contribution of particles and their corresponding released ions to the overall toxicity of CuO NPs is poorly understood. In this study, we investigated the toxicological effects of CuO NPs and their corresponding released ions on the hemocytes of Chlamys farreri. Both copper species induced membrane damage, and increased lysosome contents in hemocytes. Based on the integrated biomarker responses method, the relative contributions of particles (NPparticle) and dissolved ions (NPion) to the toxicity of CuO NPs after 2h of exposure were 62.07% and 37.93%, respectively, indicating that the particles rather than the dissolved ions were the dominant source of NP toxicity. Transmission/scanning electron microscopy analysis confirmed the greater histopathological effects exerted by particles than Cu ions. Higher reactive oxygen species (ROS) generation induced by NPparticle than by NPion suggested that the intracellular ROS production might be responsible for the NP toxicity. Our findings suggest that particles effects play a key role in risk assessment of CuO NPs on the marine ecosystem.