Dynamic OP–Gel–PVP Hydrogels with Tunable Network Properties for Injectable, Self-Healing, and Adhesive Biomaterial Applications

Injectable, self-healing hydrogels that integrate structural support, bioactivity and controlled drug delivery are attractive for the management of complex wounds, particularly in emergency or field-care settings. In this study, oxidized pectin (OP)–gelatin hydrogels incorporating poly(vinyl pyrrolidone) (PVP), protocatechuic aldehyde (PA) and procaine (PC) were prepared via dynamic Schiff-base crosslinking, and their composition–structure–function relationships were systematically examined. FTIR confirmed imine formation between OP/PA and gelatin together with preservation of the polysaccharide backbone, while increasing PVP content enhanced pyrrolidone-associated bands. SEM revealed a transition from a relatively compact, densely packed network (OP–Gel–PVP20) to a more open, fibrillar and porous structure at higher PVP loading (OP–Gel–PVP40). These morphological changes correlated with tunable viscoelasticity and self-healing behaviour, and with improved lap-shear adhesion on both dry and gelatin-coated substrates for the PVP20 and PVP40 formulations. Swelling and release studies showed that PC release could be modulated by PVP content, with OP–Gel–PVP20 exhibiting slower, more restricted release and OP–Gel–PVP40 providing faster and nearly complete release. All hydrogels maintained cell viability in the 90–95% range, and DPPH assays demonstrated significant radical-scavenging activity dominated by the phenolic contribution of PA. The OP– Gel–PVP hydrogels thus provide an injectable, self-healing and adhesive matrix with antioxidant functionality and controllable anaesthetic release, supporting their use as advanced wound dressings for tissue protection and regeneration.