Structural and Antimicrobial Characterization of Porcine and Fish Gelatin Hydrogels Photochemically Crosslinked with Menadione Sodium Bisulfite.

Gelatin-based hydrogels are promising matrices for wound management, but their direct application is constrained by insufficient structural stability and lack of intrinsic antimicrobial activity. Porcine and fish gelatin hydrogels were photochemically crosslinked with menadione sodium bisulfite (MSB), a water-soluble hemostatic derivative of vitamin K3, and characterized by ATR-FTIR and 1H NMR spectroscopy, together with antimicrobial testing against Staphylococcus aureus, Candida albicans, Escherichia coli, and Salmonella enterica. FTIR analysis showed that MSB crosslinking retards the thermal disruption of collagen-like triple helices in both gelatins, with the effect being more pronounced in porcine gelatin owing to its higher imino acid content and more developed collagen-like network. NMR measurements confirmed that crosslinking increases the bound-water fraction approximately threefold in porcine and twofold in fish gelatin, while the bulk water mobility stays unchanged. MSB crosslinking enhanced antimicrobial activity against S. aureus and C. albicans by up to 5.6-fold relative to non-crosslinked controls and additionally conferred activity against E. coli, while S. enterica remained resistant in all variants. MSB, thus, simultaneously serves as a structural crosslinker and imparts intrinsic antimicrobial activity to the resulting hydrogels, making them a promising basis for multifunctional wound-healing materials.