Rational design of Mn-MOF/MXene heterojunction microneedles for biocompatible ROS therapy of infected wounds

Reactive oxygen species (ROS) therapy represents an ideal approach for eliminating bacterial infection in skin wounds. Although nanozyme-laden hydrogels can generate ROS to accelerate wound healing, their application is commonly limited by inadequate tissue delivery, insufficient ROS generation, and potential oxidative injury to human cells. Herein, we design silk fibroin methacryloyl (SilMA) microneedles (namely S/Mn@MX) encapsulating Mn-MOF/MXene (Mn@MX) heterojunction to address these challenges. The Mn@MX heterojunction, synthesized via a hydrothermal method, exhibits a narrowed band gap (2.31 eV) and enhanced NIR-triggered charge separation, significantly improving the generation of ROS while effectively depleting bacterial glutathione. Notably, the Mn 2+ ions released by Mn@MX heterojunctions serve dual functions: they amplify bacterial oxidative stress via Fenton-like reactions, while simultaneously activating endogenous antioxidant enzymes in human cells to eliminate ROS. This selective mechanism enables potent broad-spectrum antibacterial and anti-biofilm activity without compromising human cell viability. S/Mn@MX microneedle delivers Mn@MX heterojunctions in situ and accelerates wound healing by promoting collagen deposition, angiogenesis, and M2 macrophage polarization, while reducing inflammation and oxidative stress, outperforming a commercial dressing. In conclusion, this work not only develops a bioactive microneedle material, but also establishes a novel paradigm integrating heterojunction-enhanced nanozyme catalysis with microneedle-based delivery for the management of infected wounds.