Figure 4.

Effects of TiO₂ NPs on DNA damage in BEAS-2B cells using the comet assay. BEAS-2B cells were exposed to TiO₂ NPs at doses of 25, 50 and 100 µg/mL for 48 h or the positive control of hydrogen peroxide (H₂O₂) at 1.53 mM for 5 min. (A) In the normal comet assay, no obvious comet cells were found, except for the positive control group. (B) Quantitative analysis showed no significant difference between different groups. (C) In the Fpg-modified comet assay, comet cells were found in the TiO₂ NP exposure groups. (D) Quantitative analysis of the Fpg-modified comet assay showed that both the Olive tail moment and comet tail DNA percentage in the 100 µg/mL TiO₂ NP group were significantly higher than those in the control group. Significant difference from the control (* p < 0.05).