Fig. 4
PDA NPs reduce UV-induced DNA damage. (A, B) Representative immunofluorescent images of the nuclei in HaCaT cells pretreated with 40 mg/mL PDA NPs for 24 h followed by 50 mJ/cm2 UVB. The comet tail of damaged DNA was stained with a Comet assay kit from the R&D system. The length of the comet tail was analyzed by CaspLab (CASP) software. (C, D) Representative immunofluorescent images and quantification of p53 signal in the dorsal skin of Balb/c mice after different experimental treatments (n = 4). P53 was stained with Cy3 (red) and nuclei were stained with Hoechst 33,258 (blue). (E) The p53 protein level of HaCaT cells was detected after being pretreated with different concentrations of PDA NPs (0, 20, 40, and 60 mg/mL) for 24 h, followed by exposure to UVR. (F) Semi-quantitative analysis of p53 was normalized to GAPDH. All data represent the mean ± SD. *p < 0.05, **p < 0.01 and ***p < 0.001