Fig. 2
Morphology change and viability of HaCaT cells treated with ZnONPs and UVB. A Morphological changes after treatment with ZnONPs (10 μg/mL), UVB + ZnONPs (68 mJ/cm2 + 10 μg/mL) and UVB + ZnONPs + PT (2 μM). B Cell viability assay showing the dose-dependent cytotoxicity of combined treatment with ZnONPs (0–15 μg/mL) and UVB (68 mJ/cm2). C PT treatment (0–2 μM) followed by ZnONPs (10 μg/mL) + UVB (68 mJ/cm2) significantly increased the viability of HaCaT cells. D TEM image of HaCaT cells after ZnONPs (10 μg/mL) treatment for 3 h. The autophagosome double-membrane structures (blue arrow) engulfed ZnONPs (black arrow), the mitochondrial outer membranes were swollen, and the inner cristae were highly degenerated (red arrow). Values are presented as the mean ± SD (n = 3). *p < 0.05, control group versus treatment groups. #p < 0.05, the UVB + ZnONPs groups versus the UVB + ZnONPs + PT groups. Abbreviations N nucleus, A autophagosome, Z ZnONPs, M mitochondria