Fig. 9.

In vivo NAD(P)H average lifetimes of ${\tau }_{\mathrm{m}}$ and $a_1/a_2$ of human skin either untreated or treated with coated ZnO NPs (a) repeated six times a day and (b) repeated once a day for five days, demonstrate no change in the cells of the stratum granulosum. The ZnO NPs in the furrow is seen to possess a higher $a_1/a_2$ ratio (red arrow). Data from Ref. 13 reanalyzed.