Cytotoxicity and DNA Damage Effect of TGA-capped CdTe Quantum Dots

The cytotoxicity and DNA damage caused by thioglycolic acid(TGA)-capped cadmium telluride(CdTe) quantum dots(QDs) to hepatocyte line HL-7702 were investigated. Cell viability was measured by 3-(4,5-dimethyl- thiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay; DNA damage was detected by single cell gel electro-phoresis(SCGE); the change of cell cycle progression was examined by propidium iodide(PI)-flow cytometry(FCM); apoptosis was measured by acridine orange/ethidium bromide(AO/EB) assay and Annexin V-FITC/PI-FCM(FITC: fluorescein isothiocyanate). The results show that the cytotoxicity induced by CdTe QDs was increased in a dose-dependent and time-dependent manner; after exposure to QDs for 24 h, as the exposure dose increased, the rate of DNA damage was significantly increased(P<0.05), and the degree of DNA damage was elevated. As the dose of CdTe QDs increased, the percentage of G₀/G₁ phase cells was significantly decreased(P<0.001), while the percent- tages of S and G₂/M phases cells were significantly increased(P<0.001). In AO/EB assay, apoptotic cells could be observed under a fluorescence microscope, and apoptotic rate was increased as exposure dose increased. In Annexin V-FITC/PI-FCM assay, the apoptotic rates of CdTe QDs treated groups were significantly increased compared with that of control group(P<0.05). Our studies indicate that CdTe QDs could influence cell viability, and induce DNA damage, the S and G₂/M phases arrest and apoptosis of HL-7702.