Uptake of cerium oxide nanoparticles and their influences on functions of A549 cells

The cerium oxide nanoparticles (NPs) have been widely used in the fields of fuel additives, cosmetics, commodities, pharmaceuticals and other industries. Exposure of the CeO2 NPs causes a public concern on their potential health risk. In this study, the interactions between two commercial CeO2 NPs and human bronchoalveolar carcinoma-derived A549 cells were investigated to provide a fast and in-depth understanding of the biological influences of the NPs. In the culture medium containing 10% fetal bovine serum, both of the D-CeO2 and PC-CeO2 NPs had an extremely small solubility (< 0.1 ng/mL) and were aggregated from 20 nm and 8 nm (in a dry state) to approximately 190 nm and approximately 60 nm, respectively. Both types of the CeO2 NPs showed slightly negative surface charge due to the adsorption of serum proteins. They had rather weak cytotoxicity even at the highest concentration of 200 microg/mL. Cellular uptake of the CeO2 NPs increased along with the increase of concentration and incubation time. The internalized CeO2 NPs were dispersed in vacuoles and cytoplasm. Uptake of the particles resulted in slight change of the cell cycles, i.e., more cells stayed in the G1 phase, and could suppress the production of reactive oxygen species but brought negligible influence on the mitochondrial membrane potential. However, the cytoskeleton organization and the cell adhesion ability were affected to some extent.