Photoactive Hydrogels as Materials for Biological Applications: Preparation of Thermally Stable Photoactive Films

This study reports the design and characterization of photoactive poly(HEMA-co-AAm) hydrogel films functionalized with the photochromic agent spiropyran (BSP) for biological and antimicrobial applications. The hydrogels were synthesized via photopolymerization and systematically characterized for structural, thermal, swelling, and mechanical properties. Lap shear testing demonstrated that increasing crosslinker (MBA) and BSP content significantly enhanced shear strength and adhesive performance under wet conditions. The optimized hydrogel formulation exhibited soft yet robust adhesion suitable for biomedical patch applications. In parallel, photodynamic therapy experiments showed that BSP-functionalized hydrogels combined with Ru(bpy)₂²⁺ significantly improved antimicrobial efficacy against both MSSA and MRSA strains, reducing the minimum inhibitory concentration required for complete bacterial inactivation.