pH-responsive alginate/gelatin-based hydrogel with antibacterial and antioxidant properties for enhanced infected...

Bacterial infection and oxidative stress imbalance severely impair wound healing, necessitating the development of multifunctional wound dressings. Herein, a pH-responsive nanocomposite hydrogel (AG-Zn-SC@D) was fabricated via dynamic Schiff base crosslinking between aldehyde-modified alginate and gelatin, incorporating Zn²⁺ and sophoricoside-loaded amino-functionalized dendritic mesoporous silica nanoparticles. Owing to the acidic microenvironment of infected wounds, the hydrogel exhibited a pH-responsive release profile. Under acidic stimulation, protonation of carboxyl groups accelerated Zn²⁺ release, enabling potent antibacterial activity with inhibition rates exceeding 95% against both E. coli and S. aureus. Meanwhile, the acid-triggered dissociation of Schiff base bonds facilitated sustained sophoricoside release over 72 h and conferred strong antioxidant capacity, with nearly complete DPPH• scavenging at a concentration of 60 mg/mL. In a Staphylococcus aureus-infected skin wound model, the hydrogel significantly attenuated inflammation (reducing IL-6 and MPO expression while upregulating IL-10), promoted angiogenesis and fibroblast proliferation, and enhanced collagen deposition and re-epithelialization, thereby contributing to accelerated wound closure and improved tissue regeneration. This multifunctional nanocomposite hydrogel offers a promising strategy for infected wound management.