Catalase-loaded polymersomes as a promising safe ingredient to active photoprotection

Abstract The topical application of enzymes for UV-induced damage repair, such as catalase, represents an interesting strategy for "active" photoprotection. However, catalase, a large and hydrophilic molecule, needs to penetrate the skin to present activity and, in this sense, nanocarriers can provide an aid for barrier crossing. Among the nanocarriers, polymersomes (Ps) obtained by the self-aggregation of amphiphilic block copolymers represent an alternative for topical enzyme delivery. Here, catalase-loaded Ps of Pluronic® L121, an amphiphilic triblock copolymer, were prepared by direct dissolution and in vitro evaluated regarding safety and efficacy. The Ps presented a suitable photo/cytotoxicity profile regarding the sun-damaged epidermis. Pre-clinical safety tests indicated that the HET-CAM assay was more appropriate than cytotoxicity assays to predict the irritant potential of the Ps. Based on cutaneous permeation assays associated with laser scanning confocal fluorescence microscopy, the Ps increased ten times the catalase percentage of skin permeation. Additionally, in vitro assays indicated that catalase-loaded Ps were able to eliminate UV-induced lipid peroxidation in deeper layers of the skin (viable epidermis + dermis) in comparison to free catalase. Penetration assays in 3D cell culture and efficacy assays confirmed the preferential delivery of catalase in the deeper layers of the skin owing to the permeation enhancer effect of Pluronic L121 and/or the membrane translocation capacity of the Ps. In conclusion, our findings indicate catalase-loaded Ps as an innovative nanomaterial for active sunscreens.