Assessment of the cytotoxicity of cerium, tin, aluminum, and zinc oxide nanoparticles on human cells

In the course of time, there has been an increased usage of commercial products containing nanoparticles formulated from tin oxide (TNPs), cerium oxide (CNPs), aluminum oxide (ANPs), and zinc oxide (ZNPs). Despite the wide use of metal oxide nanoparticles (MONPs), understanding about their toxicity and mechanism of action are still unclear. In the present study, TNPs, CNPs, ANPs, and ZNPs were produced by the method of chemical synthesis and characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The effect of these MONPs on human red blood cells (RBCs) and human skin cells (HaCaT) was investigated. In skin cells, these MONPs showed concentration-dependent cytotoxicity. ZNPs downregulated the glutathione and upregulated lipid peroxidation and lactate dehydrogenase activity which correlates with the increased reactive oxygen production in cells. Genotoxic effect of ZNPs was measured by comet tail assay that showed increased DNA damage in skin cells. Upregulation of Hsp70, Grp 78, and CYP1A1 was observed following ZNPs and ANPs treatment with skin cells. In the case of CNPs and TNPs, the changes were not significant. This study demonstrates the toxic effects of ZNPs and ANPs on skin cells, suggesting caution must be exercised in their use  which may be restricted in the cosmetics industry and also products related to human use.