Additional file 1: Figure S1. Particle size of TiO2, ZnO and ZIF-8. Particle size was measured using TEM and plotted thereafter. The peak sizes for TiO2, ZnO, and ZIF-8 were 102.1 nm, 114.8 nm and 82.3 nm, respectively. Figure S2. Enlarged figures for (A) Fig. 1C and (B) Fig. 1D. Figure S3. Characterization of ZIF-8 1:2. (A) PXRD pattern. (B) 1H NMR spectrum. (C) XPS spectrum. (D) N2 adsorption and desorption isotherms. (E) Pore size distribution. Figure S4. Characterization of ZIF-8 1:5. (A) PXRD pattern. (B) 1H NMR spectrum. (C) XPS spectrum. (D) N2 adsorption and desorption isotherms. (E) Pore size distribution. Figure S5. Characterization of ZIF-8 1:8. (A) PXRD pattern. (B) 1H NMR spectrum. (C) XPS spectrum. (D) N2 adsorption and desorption isotherms. (E) Pore size distribution. Figure S6. Characterization of ZIF-8 1:16. (A) PXRD pattern. (B) 1H NMR spectrum. (C) XPS spectrum. (D) N2 adsorption and desorption isotherms. (E) Pore size distribution. Figure S7. Physical and chemical characterizations of ZIF-8 (1:2, 1:5, 1:16). (A) TEM images of ZIF-8 (1:2, 1:5, 1:16). (B) Particle sizes of ZIF-8 (1:2, 1:5, 1:16). Particle size was measured using TEM and plotted thereafter. The sizes for ZIF-8 (1:2, 1:5, 1:16) were 164.8 �� 32.6 nm, 102.5 �� 26.8 nm, and 80.0 �� 37.7 nm, respectively. (C) Diffuse reflection spectra for ZIF-8 (1:2, 1:5, 1:16). UV reflectance, especially for UVB and UVC, was enhanced with decreasing the ratios of Zn2+ to 2-MeIM and reached to the highest value for ZIF-8 1:8. UV reflectance was not further increased ZIF-8 1:16. Figure S8. Characterization of TiO2. (A) PXRD pattern. (B) XPS spectrum. Figure S9. Characterization of ZnO. (A) PXRD pattern. (B) XPS spectrum. Figure S10. Characterization of MOF-5. (A) PXRD pattern. (B) 1H NMR spectrum. (C) XPS spectrum. (D) N2 adsorption and desorption isotherms. (E) Pore size distribution. Figure S11. Characterization of IRMOF-1. (A) PXRD pattern. (B) 1H NMR spectrum. (C) XPS spectrum. (D) N2 adsorption and desorption isotherms. (E) Pore size distribution. Figure S12. Characterization of Zn3L3DMF2. (A) PXRD pattern. (B) 1H NMR spectrum. (C) XPS spectrum. (D) N2 adsorption and desorption isotherms. (E) Pore size distribution. Figure S13. Physical and chemical characterizations of zinc-based MOFs. (A-C) TEM images. (A) MOF-5. (B) IRMOF-1. (C) Zn3L3DMF2. (D-F) Particle size distributions of MOF-5, IRMOF-1 and Zn3L3DMF2. Particle size was measured using TEM and plotted thereafter. The sizes were 310.6 �� 142.4 nm, 47.1 �� 13.6 nm, and 256.0 �� 91.3 nm for MOF-5, IRMOF-1, and Zn3L3DMF2, respectively. (G) The zeta potentials of TiO2, ZnO, ZIF-8, MOF-5, IRMOF-1, and Zn3L3DMF2 were 31.7 �� 0.6 mV, 16.4 �� 0.7 mV, 29.5 �� 0.8 mV, ��� 9.9 �� 1.5 mV, ��� 7.0 �� 0.6 mV, and ��� 5.6 �� 0.6 mV, respectively. (H) The degradation of zinc-based MOFs in artificial sweat (pH 6.5, 32 ��C). ZIF-8 (0.5 mg) exhibited the lowest degradation rate relative to that of MOF-5 (0.5 mg), IRMOF-1 (0.5 mg), and Zn3L3DMF2 (0.5 mg). Figure S14. EPR spectra of POBN-OH spin abduct signal produced by TiO2 suspensions in ethanol. (A) TiO2 at 800 ��g mL���1, (B) TiO2 at 50 ��g mL���1. No obvious EPR signal was detected for TiO2 at 50 ��g mL���1. Figure S15. EPR spectra of POBN-OH spin abduct signal produced by suspensions of TiO2, ZnO, and Zn-based MOFs at 800 ��g mL���1 in ethanol. (A) TiO2, (B) ZnO, (C) ZIF-8, (D) MOF-5, (E) IRMOF-1, (F) Zn3L3DMF2. ZnO produced most free radical of ��OH (1.3 �� 1012 spins/mm3), followed by TiO2 (5.9 �� 1011 spins/mm3), MOF-5 (4.1 �� 1011 spins/mm3), Zn3L3DMF2 (2.1 �� 1011 spins/mm3), IRMOF-1 (6.2 �� 1010 spins/mm3) and ZIF-8 (2.3 �� 1010 spins/mm3), suggesting Zn-based MOFs induced much less EPR signal compared to TiO2 and ZnO after UV exposure. Figure S16. UV absorbance of ZIF-8, TiO2, ZnO and 2-MeIM. ZIF-8 showed a higher UV absorbance compared to ZnO. Also, ZIF-8 revealed a higher UVB absorption relative to TiO2, though UVA absorption of is lower. Figure S17. Cell viability of (A) HaCaTs or (B) HEKas after exposed with UV in various doses. Figure S18. Fluorescence images of DNA tail after (A) HaCaTs or (B) HEKas were exposed to UV in various doses. Figure S19. ROS levels in HaCaTs after UVB exposure. (A) Confocal fluorescent images (Blue, nucleus; Green, ROS positive.). (B) Flow cytometry analyses of free radical levels in HaCaTs with/without protections. HaCaTs with ZIF-8 pretreatment showed no obvious increase of ROS. However, ROS were elevated for the cells without protection or with the protections of TiO2, ZnO, MOF-5, IRMOF-1 or Zn3L3DMF2. Figure S20. ROS levels in HEKas after UVB exposure. (A) Confocal fluorescence images (Blue, nucleus; Green, ROS positive.) and (B) flow cytometry analyses of free radicals in HEKas with/without protections. HaCaTs with ZIF-8 pretreatment showed less ROS production relative to that for the cells without protection or with the protections of TiO2, ZnO, MOF-5, IRMOF-1 or Zn3L3DMF2. Figure S21. ROS levels in HaCats after UVA exposure. (A) Confocal fluorescent images (Blue, nucleus; Green, ROS). (B) Flow cytometry analyses of free radical level in HaCats with/without protections. HaCaTs with ZIF-8 pretreatment showed no obvious ROS production. More ROS production were observed in the cells without protection or with the protections of TiO2, ZnO, MOF-5, IRMOF-1 or Zn3L3DMF2. Figure S22. ROS measurement in HEKas after UVA exposure. (A) Confocal fluorescent images (Blue, nucleus; Green, ROS.). (B) Flow cytometry analyses of free radicals in HEKas with/without protections. HEKas with ZIF-8 protection showed less ROS production relative to that for the groups of No protection, IRMOF-1, TiO2, ZnO, MOF-5, or Zn3L3DMF2. Figure S23. UV dose optimization on mouse skin. Images of mouse dorsal skin three days after UV exposure at different doses. UV dose of 206 J m���2 was selected for further use because erythema was observed at this dose. Figure S24. ZIF-8 dose optimization. Images of mouse skin three days after UV exposure with protections of TiO2, ZnO, and ZIF-8 at different doses. The dose of 15% was selected for further in vivo mouse study, because some sunburn was observed for TiO2 and ZnO mice at this dose, while no obvious erythema was observed for ZIF-8 mice at dose of 15%. Figure S25. Digital graphs of mouse dorsal skin three days after UV exposure with the protections of TiO2, ZnO, or ZIF-8. ZIF-8 group showed less ulceration, edema or erythema compared to no protection or glycerol group. Figure S26. ROS in mouse skin after UV exposure. (A) Quantitative and (B) qualitative analyses of free radical level in the skin with/without protections. Figure S27. Microscope photographs of the mouse skin with (A) Masson���s Trichrome staining or (B) IL-1�� immunohistochemistry. UV disturbed collagen distribution and decreased density for no protection and glycerol groups, while ZIF-8 group showed a normal collagen appearance. ZIF-8 also inhibited the skin expression of IL-1�� after UV exposure. Figure S28. UV dose optimization on pig skin. Digital images of pig dorsal skin 24 h after UV exposure. UV at 544 J m���2 could induce obvious erythema. Figure S29. ZIF-8 dose optimization against UV exposure on pig skin. Digital graphs of pig dorsal skin 24 h after UV exposure with protections of ZIF-8 at different doses. ZIF-8 at 15% obviously inhibited erythema formation. Figure S30. Digital graphs of pig dorsal skin 24 h after UV exposure with the protections of TiO2, ZnO, or ZIF-8. ZIF-8 obviously inhibited erythema formation. Figure S31. Blood biochemical analyses after mice were treated with TiO2, ZnO, or ZIF-8 for six times in 15 days. (A-C) Serum levels of (A) AKP, (B) ALT, and (C) AST for liver function analyses. (D-E) Serum levels of (D) BUN, and (E) CRE for kidney function analyses. Both liver and kidney functions were not affected by TiO2, ZnO, or ZIF-8. Figure S32. H&E images of main tissues after mice were treated with TiO2, ZnO, or ZIF-8 for six times in 15 days. No obvious tissue damage was observed for heart, liver, spleen, lung, and kidney in all these groups. Figure S33. The accumulations of Ti or Zn in blood and tissues after TiO2, ZnO, or ZIF-8 were applied for six times in 15 days. (A, B) Ti levels in (A) heart, liver, spleen, lung, and kidney and (B) blood for the mice with TiO2 treatment. (C, D) Zn levels in (C) heart, liver, spleen, lung, and kidney and (D) blood for the mice with ZnO or ZIF-8 treatments.