In vitro toxicity assessment of cerium oxide and zinc oxide nano-combination in human lung epithelial cells

Nanoparticles (NPs) rank among the top 10 hazardous chemicals in occupational settings worldwide. Combining nanoparticles using “mix and match” is a new approach that takes advantage of their physicochemical properties to create unique materials. One such example is CeO₂ and ZnO nano-combination, which provides protection against UVB light and enhances the structural and electrical properties of polyvinyl alcohol films. Occupational exposure to nano-mixtures can occur while fabricating nanoparticles in the same location or manipulating nano-mixtures in applications. However, the effect of these nano-cocktails on human health is not well understood.

In this study, cell viability, cell membrane integrity, oxidative stress, and inflammatory cytokines produced by lung epithelial cells were assessed in submerged conditions after treating the cells with increasing concentrations of ZnO or CeO₂ NPs alone, or a mixture of both. Microscopic images were used to assess morphological changes resulting from the NP treatments.

Results showed that ZnO NPs affect the viability of the cells in a dose-dependent manner. CeO₂ NPs did not affect the viability of the cells at any of the concentrations tested. When toxic doses of ZnO were combined with increasing doses of CeO₂, a significant loss of cell viability was observed at higher doses. This suggests that the presence of CeO₂ enhances the toxicity of ZnO in lung cells. More studies on nano-mixtures should be undertaken to inform the making of regulations to protect workers in the nanotechnology industry as well as to enhance safety of end-product users.