Comparison of Enhanced Photocatalytic Degradation Efficiency and Toxicity Evaluations of CeO 2 Nanoparticles Synthesized Through Double-Modulation.

We demonstrated that Fe/Cr doped and pH-modified CeO ₂ nanoparticles (NPs) exhibit enhanced photocatalytic performance as compared to bare CeO ₂ NPs, using photocatalytic degradation. To assess the toxicity level of these double-modified CeO ₂ NPs on the human skin, they were introduced into HaCaT cells. The results of our conventional cellular toxicity assays (neutral red uptake and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide for assays) indicated that Cr@CeO _x NPs prompt severe negative effects on the viability of human cells. Moreover, the results obtained by scanning transmission X-ray microscopy and bio-transmission electron microscope analysis showed that most of the NPs were localized outside the nucleus of the cells. Thus, serious genetic toxicity was unlikely. Overall, this study highlights the need to prevent the development of Cr@CeO _x NP toxicity. Moreover, further research should aim to improve the photocatalytic properties and activity of these NPs while accounting for their stability issues.