Chitosan/oxidized sodium alginate double-network hydrogel incorporated with Zn-BTC: leveraging MOF-polymer interaction mechanisms for enhanced mechanical properties and sustained antibacterial activity

Conventional wound dressings struggle to conform to wounds located near stretchable body surfaces due to frequent skin movement and stretching. Furthermore, wounds in motion areas are often complicated by persistent infections. To meet these demands, we propose a novel CS/OSA/ZnBTC hydrogel by incorporating Zn-BTC (BTC = benzene-1,3,5-tricarboxylate) as a dual-functional nanofiller into a chitosan/oxidized sodium alginate (CS/OSA) double-network hydrogel. Mechanical testing revealed that the CS/OSA/ZnBTC hydrogel with a Zn-BTC doping concentration of 3 wt% exhibits enhanced mechanical properties, with its fracture tensile stress reaching 0.23 MPa, representing a 3.8-fold increase compared to the CS/OSA hydrogel. The Zn 2+ release kinetics of the CS/OSA/ZnBTC hydrogel, evaluated using the Korsmeyer-Peppas model combined with experimental measurements, confirmed a controlled release profile sustained over 120 h. Antibacterial tests and a mouse wound model were conducted to further validate the enhanced mechanical properties and sustained Zn 2+ release capability of the hydrogel. The results confirmed that the CS/OSA/ZnBTC hydrogel exhibits superior sustained antibacterial effect and effectively facilitate wound healing compared to the CS/OSA hydrogel. Molecular dynamics simulations revealed the interaction mechanisms between Zn-BTC and the CS/OSA matrix at the molecular level, specifically enhanced hydrogen bonding interactions and ionic coordination. This novel Zn-BTC-incorporated chitosan-based double-network hydrogel presents new perspectives for managing wounds at frequently moving sites.