Arbutin/kojic acid-loaded MHA hydrogel array patches attenuate UVB-induced epidermal hyperplasia and...

Acute ultraviolet B (UVB) exposure induces epidermal hyperplasia, pigmentation-related responses, and early extracellular matrix remodeling. Topical tyrosinase inhibitors, including arbutin and kojic acid, can have limited residence on damaged skin. Here, we evaluated a skin-conformal composite patch comprising aligned polyurethane nanofiber membranes integrated with methacrylated hyaluronic acid (MHA) hydrogel arrays loaded with arbutin or kojic acid. Seven-week-old Hairless Mouse, Strain 2 (HRM2) mice were assigned to six groups: control (CTL), UVB only (UV), UVB plus topical arbutin (UVA), UVB plus topical kojic acid (UVK), UVB plus arbutin-loaded MHA patch (UV-A-MHA), and UVB plus kojic acid-loaded MHA patch (UV-K-MHA). Dorsal skin received a single UVB dose (200 mJ/cm²), was treated immediately, and was analyzed on Day 4. Drug-loaded MHA patch treatment attenuated UVB-induced epidermal thickening and was associated with qualitative differences in dermal matrix organization, while direct comparisons with the corresponding freely applied formulations varied across endpoints. These histological findings were evaluated using hematoxylin and eosin, Masson's trichrome, Picro-Sirius Red, and Fontana-Masson staining. GFP-loaded MHA hydrogels remained detectable in the epidermis and upper dermis through Day 4, supporting local cargo retention under skin-contact conditions. Preliminary HPLC-UV analysis detected arbutin and kojic acid parent peaks in MHA formulations before and after 60 s of UV exposure. Patch treatment was associated with significant reductions in α-smooth muscle actin and vimentin, whereas effects on SMAD phosphorylation differed between the two drug formulations, without detectable changes in body weight or serum TNF-α and IL-6. Because the main experiment lacked drug-free MHA patch and bandage-only controls, scaffold-, occlusion-, and drug-specific effects could not be fully separated. These findings support aligned nanofiber-supported MHA hydrogel arrays as functional biomaterial patches for localized cutaneous delivery and modulation of acute UVB-induced remodeling-associated responses.