Comparative Cytotoxicity of Al₂O₃, CeO₂, TiO₂ and ZnO Nanoparticles to Human Lung Cells

The increased applications of nanoparticles in a wide range of industrial fields raise the concern about their potential toxicity to human. The aim of this study was to assess and compare the toxicity of four different oxide nanoparticles (Al₂O₃, CeO₂, TiO₂ and ZnO) to human lung epithelial cells, A549 carcinoma cells and L-132 normal cells, in vitro. We focused on the toxicological effects of the present nanoparticles on cell proliferation, cell viability, membrane integrity and oxidative stress. The long-term cytotoxicity of nanoparticles was also evaluated by employing the clonogenic assay. Among four nanoparticles tested, ZnO exhibited the highest cytotoxicity in terms of cell proliferation, cell viability, membrane integrity and colony formation in both cell lines. Al₂O₃, CeO₂ and TiO₂ showed little adverse effects on cell proliferation and cell viability. However, TiO₂ induced oxidative stress in a concentration- and time-dependent manner. CeO₂ caused membrane damage and inhibited colony formation in long-term, but with different degree depending on cell lines. Al₂O₃ seems to be less toxic than the other nanoparticles even after long time exposure. These results highlight the need for caution during manufacturing process of nanomaterials as well as further investigation on the toxicity mechanism.