纳米与常规二氧化钛对A549细胞毒性及DNA损伤的比较

目的]比较纳米二氧化钛（nano-TiO2）和常规TiO2对细胞的毒性及DNA损伤有无差异。方法]体外培养人肺腺癌细胞（A549细胞），采用四甲基偶氮唑盐比色法（MTT）和单细胞凝胶电泳技术（彗星实验）比较25、50、100、200μg／mL质量浓度（以下简称“浓度”）的nano-TiO2（5-10nm）和常规TiO2的细胞毒性与DNA损伤作用。结果]nano-TiO2对A549细胞的毒性与常规TiO2的变化趋势相近，nano-TiO2毒性大于常规TiO2，200gg／mL浓度时作用12h以上两者细胞存活率的差异有统计学意义（P〈0．05）。与对照组相比，nano-TiO2各剂量组尾DNA含量、Olive尾距、彗星尾长均明显增加（P〈0．05）；常规TiO2在受试剂量下尾DNA含量、Olive尾距、彗星尾长与对照组比较均无明显增加。结论]nano-TiO2对A549细胞的毒性高于常规TiO2，且nano-TiO2可诱导DNA损伤，而常规TiO2未观察到DNA损伤作用。表明nano-TiO2与常规TiO2在毒性大小和毒作用性质均有差异。

Comparative Study of Cytotoxicity and DNA Damage Induced by Nano- and Micro-TiO2 Particles on A549 Cells in Vitro

Objective ] To compare the difference between nano-and micro-TiO2 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 200 μg/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-TiO2 and micro-TiO2 was similar, but at the same level, nano-TiO2 induced greater damage than the micro-TiO2. For example, after 12 h treatment, nano-TiO2 in a dose of 200 μg/mL inhibited the viability of A549 cells significantly compared with the micro-TiO2 group. In addition, compared to the control group, the tail DNA content, Olive tail moment and comet tail length of the nano-TiO2 group increased significantly （ P〈0.05 ）; whereas these indices in micro-TiO2 group did not change. Conclusion ] Our data demonstrates that nano-TiO2 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-TiO2, and nano-TiO2 particles can induce DNA damage, but micro-ones do not. It is shown that the nano- and micro-TiO2 particles have some differences in toxicity and toxic properties.