Photoactive Hydrogels Containing Merocyanine/Spiropyran Units for Wound Dressing Applications

Chronic wounds present alkaline, microbially burdened environments that impede tissue repair and necessitate materials capable of actively modulating local chemistry. Here, we report the synthesis and characterization of light-responsive hydrogels incorporating a methacrylate-functionalized merocyanine photoacid (E-MCMAH⁺) within the OEGMA/EGDMA networks to enable spatiotemporal control over acidity. Systematic variation of photoacid loading revealed its critical role in governing network swelling, mechanical integrity, and optical transitions associated with spiropyran-merocyanine interconversion. Solid-state UV-vis spectroscopy coupled with Tauc analysis elucidated distinct band gap features arising from photoisomerization. Under visible and UV irradiation, the hydrogels exhibited robust, reversible proton release, which translated to enhanced ion mobility confirmed electrochemically. Cytocompatibility studies demonstrated high fibroblast viability in the dark and only transient photochemical effects under blue light. Notably, the materials displayed inherent antibacterial activity against Pseudomonas aeruginosa and MRSA, which intensified to complete eradication under illumination. These properties position E-MCMAH⁺ hydrogels as versatile platforms for advanced wound dressings.