Oxidative stress contributes to cobalt oxide nanoparticles-induced cytotoxicity and DNA damage in human hepatocarcinoma cells

Background: Cobalt oxide nanoparticles (Co(3)O(4)NPs) are increasingly recognized for their utility in biological applications, magnetic resonance imaging, and drug delivery. However, little is known about the toxicity of Co(3)O(4)NPs in human cells. Methods: We investigated the possible mechanisms of genotoxicity induced by Co(3)O(4)NPs in human hepatocarcinoma (HepG2) cells. Cell viability, reactive oxygen species (ROS), glutathione, thiobarbituric acid reactive substance, apoptosis, and DNA damage were assessed in HepG2 cells after Co(3)O(4)NPs and Co2+ exposure. Results: Co(3)O(4)NPs elicited a significant (P<0.01) reduction in glutathione with a concomitant increase in lipid hydroperoxide, ROS generation, superoxide dismutase, and catalase activity after 24- and 48-hour exposure. Co(3)O(4)NPs had a mild cytotoxic effect in HepG2 cells; however, it induced ROS and oxidative stress, leading to DNA damage, a probable mechanism of genotoxicity. The comet assay showed a statistically significant (P<0.01) dose- and time-related increase in DNA damage for Co(3)O(4)NPs, whereas Co2+ induced less change than Co(3)O(4)NPs but significantly more than control. Conclusion: Our results demonstrated that Co(3)O(4)NPs induced cytotoxicity and genotoxicity in HepG2 cells through ROS and oxidative stress.