(350m) Microencapsulated UV Filters@ZIF-8 Sunscreens for Broad Spectrum UV Protection

Sunscreens play a vital role in protecting human skin from photodamage upon UV exposure, but their effectiveness is limited by degradation and phototoxicity. Photoactivation of UV filters in sunscreen can generate reactive oxygen species, with accompanying cytotoxicity. Herein, we report stable, safe, fluorescent, and long-lasting sunscreens produced by microencapsulation of organic UV filters octylmethoxycinnamate (OMC) and butyl-methoxydibenzoylmethane (BMDM) alone and in combination into mesoporous zeolitic imidazole frameworks (ZIF-8). The visibly transparent OMC@ZIF-8, BMDM@ZIF-8, and OMC+BMDM@ZIF-8 sunscreens displayed complete broad-spectrum photoprotection against UV light even after 24 hours. Photostability testing of the designed sunscreens demonstrated the photo-protective nature of mesoporous ZIF-8 for stabilizing these UV filters. The sun protection factor (SPF) values for 10% (w/w) OMC@ZIF-8, BMDM@ZIF-8 and OMC+BMDM@ZIF-8 sunscreens decreased from 29.8 to 26.0, 32.5 to 26.4, and 62.1 to 53.0, respectively upon 24 hours of UV exposure. No release of the UV filters from the encapsulated formulations was observed. The ZIF-8 particles are too large to be transported across the stratum corneum. Thus, our findings suggest that zeolitic framework-encapsulated sunscreens could provide prolonged UV-protection efficacy and ultra-high SPF with reduced potential for degradation, phototoxicity, and transport across the skin.