SOD mimetic cerium oxide nanorods protect human hepatocytes from oxidative stress

Recently, cerium oxide nanoparticles (CeNPs) have emerged as potential materials for several biomedical applications due to their excellent biocompatibility and biological enzyme-like activities. The mechanism of observed antioxidant (superoxide dismutase and catalase) enzyme-like activities of spherical-shaped CeNPs is suggested due to the switching between its two oxidation states (3+ and 4+). The shape of nanoparticles plays a significant role in controlling the catalytic activity; therefore, we have studied the antioxidant enzyme-like activities of cerium oxide nanorods. Our results suggest that CeNPs (rods) display excellent SOD-like activity as well as auto regeneration ability of its surface “Ce” atoms, comparable to CeNPs (spheres). The cytotoxicity and genotoxicity studies of CeNPs (rods) showed non-toxicity to WRL-68 (human hepatocyte) cells and impart protection from the harmful effects of reactive oxygen species generated in the presence of Buthionine sulfoximine (BSO). BSO exposure induces inhibition of glutathione (GSH) synthesis that regulates the redox status of the cytosol. The cellular internalization of CeNPs (rods) in WRL-68 cells revealed quick uptake by the cells in a time and concentration-dependent manner. The surface regeneration property of CeNPs (rods) was analysed in the presence of hydrogen peroxide (H2O2). Results suggested that the atoms present on the surface of CeNPs (rods) were oxidised into “4+” states after the addition of H2O2. After incubation of 15 days, they regained their original “3+” oxidation state by regenerating their surface, similar to spherical nanoparticles.