Bio-effects of Nano-TiO2 on DNA and cellular ultrastructure with different polymorph and size

In this paper, we investigated the bio-effect of three kinds of nano-TiO2 on the aspects of DNA strand breaking activity, generation of 8-hydroxy-2-deoxyguanosine (8-OHdG), cytotoxicity and cell morphology. Different extents of strand scission and the formation of 8-OHdG in DNA were obtained after treated with different types of nano-TiO2 (10 – 20 nm anatase, 50 – 60 nm anatase and 50 – 60 nm rutile). Furthermore, MTT assay and TEM detection showed the toxic effects on CHO cells with a toxic order as 10 – 20 nm anatase > 50 – 60 nm anatase > 50 – 60 nm rutile, which was consistent with that of 8-OHdG generation and DNA strand breaking activities. It was interesting that three kind of nano TiO2 all had much higher toxic effect on tumor cells than on normal cells, and nano-TiO2 was observed in the cytoplasm of CHO cells. These results indicated that the toxic effect of nano-TiO2 relates to the size and type of particles, in addition, their potential application for cancer treatment was discussed.