A multi-crosslinked gallic acid-modified chitosan/silk fibroin hydrogel incorporating copper-doped bioactive glass for immunomodulation and vascularized skin regeneration

Abstract

Efficient wound healing requires coordinated immunomodulation, angiogenesis, and tissue regeneration. Herein, a multi-crosslinked hydrogel composed of gallic acid-modified chitosan (GACS), silk fibroin (SF), and aminated copper-doped bioactive glass nanoparticles (CuNBG) was developed for skin regeneration. Covalent and physical interactions among GACS, SF, and CuNBG generated a mechanically reinforced hydrogel network with sufficient elasticity and injectability. The incorporation of CuNBG enabled sustained release of Cu²⁺, Ca²⁺, and Si⁴⁺ ions and enhanced endothelial cell migration and tube formation. In vitro studies demonstrated that the hydrogels exhibited antibacterial and hemostatic activities and modulated macrophage polarization toward a CD206⁺/CD80⁻ phenotype. In a full-thickness skin wound model, GACS/SF/CuNBG hydrogels accelerated wound closure and promoted tissue regeneration by day 10. Histological analysis showed enhanced re-epithelialization and collagen remodeling in the GACS/SF/CuNBG-treated groups. Immunofluorescence and immunohistochemical analyses further demonstrated increased CD31- and α-SMA-positive vascular structures, increased CD206 expression, reduced CD80 expression, and reduced expression of TNF-α and IL-6, suggesting enhanced angiogenesis-related responses and attenuation of inflammatory responses. Overall, the GACS/SF/CuNBG hydrogel represents a multifunctional platform with potential for promoting wound healing and skin regeneration.