Bioinspired synergistic chitosan–graphene–tannin hydrogel orchestrates inflammation resolution and accelerates skin tissue repair

Abstract

Wound healing remains a major clinical challenge due to the complex metabolic disturbances present within the wound microenvironment. In this study, we report the development and comprehensive validation of a novel multifunctional hydrogel composed of chitosan (CS), reduced graphene oxide (rGO), and tannins (TA) (CS-rGO-TA), specifically engineered as an advanced wound dressing. The hydrogel was thoroughly characterized using SEM to examine its porous microstructure, FTIR to analyze component interactions, the DPPH assay to assess antioxidant capacity, and total phenols to evaluate the release kinetics of TA. Antibacterial activity was tested in vitro against Escherichia coli and Staphylococcus aureus using standard colony-forming unit assays. Biocompatibility and regenerative potential were assessed through cell viability and migration assays using human dermal fibroblasts. In vivo evaluation included a skin irritability model in guinea pigs and a full-thickness excisional wound model in rats, divided into four treatment groups. Wound closure progression was monitored over time, and histological analysis was performed using hematoxylin and eosin (H&E), Mallory, and Masson's Trichrome staining to assess tissue morphology and collagen deposition. The CS-rGO-TA₃ hydrogel demonstrated controlled and sustained TA release, strong antioxidant and antibacterial properties, and excellent biocompatibility, with no signs of irritation or adverse effects. Its application significantly accelerated wound closure and promoted organized deposition of collagen (types I and III). Molecular analysis revealed early resolution of inflammation, enhanced angiogenesis, and polarization of macrophages toward a reparative M2 phenotype, as evidenced by modulation of markers such as MPO, CD68, ARG1, and interleukins IL-6, IL-10, IL-1β, and IL-1rn. Collectively, these findings highlight the CS-rGO-TA₃ hydrogel as a safe and effective therapeutic platform with strong potential for tissue regeneration and clinical wound management.