Cytotoxicity of cuprous oxide nanoparticles to fish blood cells: hemolysis and internalization.

Cuprous oxide nanoparticles (CuO NPs) possess unique physical and chemical properties which are employed in a broad variety of applications. However, little is known about the adverse effects of CuO NPs on organisms. In the current study, in vitro cytotoxicity of CuO NPs (ca. 60 nm in diameter) to the blood cells of freshwater fish Carassius auratus was evaluated. A concentration-dependent hemolytic activity of CuO NPs to red blood cells (RBCs) and the phagocytosis of CuO NPs by leukocytes were revealed. The results showed that dosages of CuO NPs greater than 40 μg/mL were toxic to blood cells, and could cause serious membrane damage to RBCs. The EC value of CuO NPs as obtained from RBCs and whole blood exposure was 26 and 63 μg/mL, respectively. The generation of reactive oxygen species and the direct interaction between CuO NPs and the cell membrane were suggested as the possible mechanism for cytotoxicity, and the intrinsic hemolytic active of CuO NPs was the main contributor to the toxicity rather than solubilized copper ions. The adsorption of plasma proteins on the surfaces of CuO NPs led to their aggregation in whole blood, and aggregate formation can significantly alleviate the hemolytic effect and subsequently mediate the phagocytosis of CuO NPs by leukocytes. [ABSTRACT FROM AUTHOR]