Evaluation of the Cytotoxicity and Oxidative Stress Response of CeO₂-RGO Nanocomposites in Human Lung Epithelial A549 Cells

Graphene-based nanocomposites have attracted enormous interest in nanomedicine and environmental remediation, owing to their unique characteristics. The increased production and widespread application of these nanocomposites might raise concern about their adverse health effects. In this study, for the first time, we examine the cytotoxicity and oxidative stress response of a relatively new nanocomposite of cerium oxide-reduced graphene oxide (CeO₂-RGO) in human lung epithelial (A549) cells. CeO₂-RGO nanocomposites and RGO were prepared by a simple hydrothermal method and characterized by relevant analytical techniques. Cytotoxicity data have shown that RGO significantly induces toxicity in A549 cells, evident by cell viability reduction, membrane damage, cell cycle arrest, and mitochondrial membrane potential loss. However, CeO₂-RGO nanocomposites did not cause statistically significant toxicity as compared to a control. We further observed that RGO significantly induces reactive oxygen species generation and reduces glutathione levels. However, CeO₂-RGO nanocomposites did not induce oxidative stress in A549 cells. Interestingly, we observed that CeO₂ nanoparticles (NPs) alone significantly increase glutathione (GSH) levels in A549 cells as compared to a control. The GSH replenishing potential of CeO₂ nanoparticles could be one of the possible reasons for the biocompatible nature of CeO₂-RGO nanocomposites. Our data warrant further and more advanced research to explore the biocompatibility/safety mechanisms of CeO₂-RGO nanocomposites in different cell lines and animal models.