The diluted nano-TiO₂ was used to treat 293T cells and CHO cells. 293T represents human kidney epithelium which belongs to normal cells, while CHO represents Chinese hamster ovary tumor cells. With the method of MTT assay, inverted microscope and DNA ladder experiment, the cytotoxic and apoptosis effects of nano-TiO₂ on the two types of cells were studied. The results indicated that nano-TiO₂ had much more severe toxic effect on CHO cells. After treatment, nano-TiO₂ entered into the CHO cells and also induced cell apoptosis. These reactions did not take place in the case of 293T, although nano-TiO₂ suppressed the multiplication of 293T. This finding might be significant for cancer therapy.

Key words: nano-TiO₂, CHO cell, 293T cell, apoptosis, cytotoxicity