Antioxidant and biocompatible hydrogel based on genipin-crosslinked quaternized chitosan and tannic acid for skin repair.

This study proposes a method for producing quaternized chitosan and genipin cross-linked hydrogels with adjustable mechanical properties to promote cell proliferation and, in turn, enhance skin repair. In this method, tannic acid at varying volume fractions is added to the quaternized chitosan and base-catalyzed crosslinked polymer dispersion system, forming hydrogels with different elastic moduli. The mechanical properties of the hydrogels are characterized using a rheometer and a universal testing machine. The mechanical properties of the quaternized chitosan and genipin cross-linked hydrogels can be adjusted by the addition of tannic acid. The elastic modulus of the quaternized chitosan hydrogel ranges from 110 to 1000 Pa. The quaternized chitosan hydrogel exhibits adhesiveness to various substrate materials as well as synergistic swelling capabilities. Additionally, the catechol groups of tannic acid aid in scavenging free radicals, which helps alleviate oxidative stress in the wound area. Quaternized chitosan-based hydrogels derive antibacterial properties from their cationic groups, which compromise bacterial membrane integrity and ensure a clean wound environment. In a full-thickness skin defect rat model, treated wounds showed markedly faster re-epithelialization, achieving complete closure within 8 days. Furthermore, these multifunctional hydrogels exhibit robust mechanical stability under high strain, ensuring prolonged wound adherence. Overall, they present a promising approach for chronic wound management by offering both antibacterial protection and mechanical compatibility.