Fig. 4

Comet assay of NHBE cells exposed to CdSe or InP QDs. NHBE cells were incubated with 5 or 80 µg/mL CdSe or InP QDs for 24 h and oxidative DNA damage (strand breaks) was measured by comet assay. a Typical microscopic images of single comets from cells exposed to CdSe or InP QDs compared to medium only negative and positive H₂O₂ controls. b A significant increase in (p < 0.0001) in DNA damage was observed for cells treated with both 5 and 80 μg/mL CdSe QDs compared to two sets of medium only negative controls (matched to 5 and 80 μg/mL experiments). Two sets of 250 μmol/L H₂O₂ positive controls (matched to 5 and 80 μg/mL experiments) are also shown for comparison. No DNA damage was apparent in cells exposed to InP QDs.***p < 0.0001; *p < 0.01. Error bars represent one standard deviation (n = 30 cells)