Comparative Study of Cytotoxicity and DNA Damage Induced by Nano-and Micro-TiO_2 Particles on A549 Cells in Vitro

[Objective]To compare the difference between nano- and micro-TiO_2 particles in their cytotoxicity and DNA damage effects on A549 cells.[Methods]A549 human lung adenocarcinoma cells were exposed to different concentrations of these two particles(0,25,50,100 and 200μg/mL ) separately,the methyl thiazolyl tetrazolium(MTT) assay and the single cell gel electrophoresis(comet assay ) were applied to measure the cytotoxicity and DNA damage.[Results]It showed that the developed trend of the cytotoxicity induced by nano-TiO_2 and micro-TiO_2 was similar,but at the same level,nano-TiO_2 induced greater damage than the micro-TiO_2.For example,after 12 h treatment,nano-TiO_2 in a dose of 200μg/mL inhibited the viability of A549 cells significantly compared with the micro-TiO_2 group.In addition,compared to the control group,the tail DNA content,Olive tail moment and comet tail length of the nano-TiO_2 group increased significantly(P0.05 );whereas these indices in micro-TiO_2 group did not change.[Conclusion]Our data demonstrates that nano-TiO_2 particles possess a toxic potential towards A549 cells which may be significantly higher than micro ones;the toxic effects occur earlier in time and lower in dose compared with micro-TiO_2, and nano-TiO_2 particles can induce DNA damage,but micro-ones do not.It is shown that the nano- and micro-TiO_2 particles have some differences in toxicity and toxic properties.