Chitosan hydrogels loaded with pH-responsive nanozymes for precision treatment of wound infection

Chronic wounds often exhibit protracted healing processes, predominantly attributed to the pervasive presence of bacterial pathogens. Nanozymes with reactive oxygen species (ROS) generation capabilities have become a burgeoning strategy within the realm of antibacterial intervention. However, an overabundance of toxic ROS can cause damage to healthy tissues surrounding the wound or during the tissue regeneration phase. Thus, there is a need for an accurate antibacterial dressing that can be applied directly to wounds. In this study, we fabricated chitosan hydrogels loaded with pH-responsive palladium (Pd) nanozymes (Pd@QCS/OD) for precision treatment of wound infection. The peroxidase-like activity of Pd enzymes can be triggered by the acidic microenvironment of infected wounds and then generate many poisonous hydroxyl radicals to achieve precise antibacterial behavior. Moreover, chitosan hydrogels synthesized via a Schiff base reaction are conducive to subsequent tissue regeneration. Both in vitro and in vivo experiments demonstrated that the Pd@QCS/OD hydrogels had effective antibacterial effects and accelerated wound recovery. This research offers some insight into the precise treatment of bacterial infections. • Development of a hydrogel dressing for precise treatment of wound infection. • The dressing was prepared from chitosan hydrogels loaded with palladium nanozymes. • The dressing can generate hydroxyl radicals in an acidic environment to kill bacteria precisely.