In situ crosslinked electrospun gelatin matrix with unoxidized tannic acid through stable hydrogen bonding

Abstract

AbstractThis study aims to comprehend the mechanism of in situ crosslinking of gelatin (Gel) with tannic acid (TA) in an unoxidized environment due to TA's biocompatibility, hydroxyl group abundance, and non‐covalent bonding capability. The crosslinking of gelatin in an unoxidized medium offers advantages over oxidized, including enhanced biocompatibility and simplified reaction conditions. In this study, 20% (w/v) gelatin was crosslinked with varying TA percentages at 45°C, followed by electrospinning to obtain fibrous mats using acetic acid (AA) as the solvent. Increasing TA content resulted in a transition from nanoscale to microscale fiber diameter, indicating increased intermolecular and intramolecular hydrogen bonding. The tensile strength of Gel/TA‐5% was 5.6 MPa, surpassing the Gel/TA‐18% sample, suggesting fewer grafting and branching reactions within TA itself. The stability of the gelatin matrix was evaluated through fiber degradation rates within the initial 7‐day period, with percentages of 25%, 38%, 50%, and 85% observed for 18%, 15%, 10%, and 5% TA concentrations, respectively. The swelling percentage of fibrous mats in a buffer solution of pH 7.4 was highest for Gel/TA‐5% at approximately 290%. At lower TA concentrations, the crosslinking density is constrained; hence, progressive fiber disassembly at pH 7.4 improves the TA release, resulting in greater antibacterial efficacy in the first 4 h. Thus, electrospun fibers from in situ crosslinked gelatin with TA in an unoxidized medium holds promise for applications such as drug delivery and wound dressing, owing to the improved properties and enhanced release capabilities of the resulting gelatin‐based fibers