Biodegradable free-standing polysaccharide films incorporating sericin and snail secretion filtrate: A...

The aim of this study was to develop a multifunctional, biodegradable wound dressing combining microbial protection, structural integrity, moisture regulation, bioactive compound delivery, and degradability within a single platform. Free-standing cross-linked films were fabricated by sequential solvent casting of two oppositely charged polymeric solutions: an anionic CMC/hyaluronate matrix containing sericin and Helix aspersa Müller secretion filtrate (SSF), and a cationic chitosan solution. Formulation was optimized in terms of composition, SSF incorporation into the anionic or cationic solution, and film thickness. The resulting films prevented penetration of the tested bacterial strains (S. aureus and P. aeruginosa) for 24 h, regardless of SSF localization. Compared with uncross-linked chitosan-free formulations, cross-linking markedly improved structural stability while preserving high swelling capacity and susceptibility to oxidative degradation. Film composition and thickness modulated swelling, degradation kinetics, and moisture regulation. ATR-FTIR and SEM analyses supported partial penetration of chitosan into the anionic matrix, resulting in a cross-linked region and a distinct bilayer architecture. The films also exhibited suitable mechanical performance, UV barrier properties, and transparency. Release studies demonstrated rapid protein release, predominantly represented by sericin. The released components showed good cytocompatibility toward HaCaT cells, while scratch assays demonstrated significantly enhanced keratinocyte migration. Sericin emerged as the main contributor to this effect, whereas SSF alone showed no significant pro-migratory activity. Overall, this study provides proof of concept for a multifunctional wound dressing combining microbial barrier function, susceptibility to degradation under simulated oxidative conditions, moisture management, tunable physicochemical properties, and bioactivity.