Actively contractible and antibacterial hydrogel for accelerated wound healing

Adhesive hydrogel has drawn great attention for wide applications in wound healing owing to its excellent biocompatibility and lasting adhesiveness. However, traditional adhesive hydrogels only keep the wound moist to promote wound healing. It is still imperative to fabricate adhesive hydrogels that exhibit efficient antibacterial ability, active driving dynamic wound closure, and reactive oxygen species (ROS) scavenging together with excellent mechanical properties. Here, a novel hydrogel based on poly(N-isopropyl acrylamide) (PNIPAAm), a thermoresponsive polymer, and tannic acid (TA)-Ag nanoparticles (TA-Ag NPs) exhibiting active contraction, tissue adhesion, anti-inflammatory and antibacterial functions was developed. TA-Ag dispersed in the hydrogel not only functioned as the catalyst to polymerize the reaction but also provided additional anti-inflammatory and antibacterial properties. Besides, tannic acid containing catechol groups endowed the hydrogel with adhesive ability. More interestingly, the obtained hydrogel exhibited the thermoresponsive shrinkage ability, which could mechanically drive wound closure due to the presence of PNIPAAm network. In vivo mouse full-thickness skin defect model demonstrated that this actively contractible and antibacterial hydrogel is a promising dressing to improve wound healing process by accelerating tissue regeneration and preventing bacterial infection. Therefore, this multi-functional adhesive hydrogel developed here may provide a new possibility for wound healing.