Fig. 7. The density of zinc ions in GES-1 cells after co-incubation with 15 mg L⁻¹ of ZnO NPs, 500 mg L⁻¹ of CPP, 300 mg L⁻¹ of VC with different systems for 24 h. The cells were stained with TSQ. (a) The control cells; (b) the cells treated with (ZnO + CPP) for 24 h; (c) the cells treated with (CPP + VC) for 24 h; (d) the cells treated with (ZnO + CPP) for 12 h + VC for 12 h; (e) the cells treated with (CPP + VC) for 12 h + ZnO for 12 h; (f) the cells treated with (ZnO + CPP + VC) for 24 h; (g) the cells treated with (ZnO + VC) for 24 h; (h) the cells treated with (ZnO + VC) for 12 h + CPP for 12 h. (i) Analysis of the average fluorescence intensity of zinc ions in GES-1 cells after incubation with different groups for 24 h. **P < 0.01 compared with the ZnO NPs plus CPP group, ^##p < 0.01 compared with the ZnO NPs plus VC group.