Chronological adaptive polyoxometalate-based hydrogel for diabetic chronic wounds through synchronous bacterial ferroptosis death and immunomodulation

Chronic wounds are a serious complication for diabetic patients, causing substantial inconvenience and significant economic burden to patients, due to their characteristics of sequential development encountering bacterial infections, excessive reactive oxygen species (ROS)-induced inflammation and M1 macrophage accumulation. Herein, we developed a chronological adaptive Fe-based polyoxometalate on hyaluronic acid (Fe-POM@HA) hydrogel for diabetic chronic wounds, whose capacity can be strengthened by synergistic the acid-activated and glutathione-enhanced NIR-II photothermal therapy and achieving spatiotemporal selective and adaptive inhibition of bacterial infection. During the bacteria-infection slightly acidic stage, Fe-POM catalyzes endogenous H 2 O 2 for ROS generation inducing bacterial ferroptosis, suppressing glutathione peroxidase activity, and promoting lipid peroxidation to disrupt the bacterial biofilm. As the wound transitions to neutral inflammation stage, Fe-POM with Fe 2+ /Mo 5+ mixed valences can simultaneously alleviate oxidative stress and overcome the hypoxia microenvironment by continuously scavenging excessive ROS for endogenous H 2 O 2 cyclic accumulation and O 2 sustainable replenishment. Importantly, the Fe-POM@HA hydrogel could further promote wound angiogenesis at the new tissue proliferation stage through the immunomodulation of macrophage polarization and inflammatory factor expression. Therefore, Fe-POM@HA hydrogel provides a promising chronologically adaptive protocol for the repair and regeneration of chronic cutaneous wounds addressing complex clinical demands.