Antibacterial and antioxidative hydrogel dressings based on tannic acid-gelatin/oxidized sodium alginate loaded with zinc oxide nanoparticles for promoting wound healing

Wound infection resulting in delayed wound healing and wound deterioration remains a clinical challenge. Recently, multifunctional hydrogel dressing was a promising strategy which has attracted wide attention in preventing wound infection and promoting wound healing. In this study, a hybrid hydrogel made of gelatin (GL), tannic acid (TA), oxidized sodium alginate (OSA), and zinc oxide nanoparticles (ZnO NPs) was prepared mainly by double network cross-linking approach, named tannic acid-gelatin/oxidized sodium alginate/zinc oxide (TAGL/OSA/ZnO). The composite hydrogels exhibited improved mechanical properties, which provided by TA modified the structure of GL network, Schiff base reaction between GL and OSA, and the strengthening effect of ZnO NPs. Meanwhile, the composite hydrogel showed high antibacterial activity against Staphylococcus aureus (S. aureus) (97.8 % +/- 0.9 %) and Escherichia coli (E. coli) (96.6 % +/- 1.2 %), attributed to the synergistic effect of TA and ZnO NPs. Furthermore, benefiting from the good antioxidative properties of TA, the sustain-released Zn2+ with the good capability to kill bacteria, and promoting the regeneration of skin epithelial tissues in BALB/c mice constantly, the multifunctional hydrogel had a significant therapeutic effect on wound healing and broad application prospects.