Defect engineering of zinc-based metal organic framework with enhanced ROS generation for antibacterial and wound healing applications

Bacterial infection in chronic skin defect poses a global healthcare challenge, fueled by antibiotic overuse and bacterial resistance. Zinc-based metal-organic frameworks (Zn-MOFs) with pro-oxidative nanozyme-like activity and broad-spectrum antibacterial activity, complemented by their inherent biocompatibility, have emerged as a promising alternative to antibiotics. However, the translational applications of Zn-MOFs are limited by suboptimal enzyme-mimicking catalytic activity, inadequate biodistribution and target site accumulation. To overcome these limitations, this study establishes a strategy of oxygen vacancy (Ov)-based defect engineering combined with microneedle-mediated transdermal delivery. An Ov-rich Zn²⁺/H₂BDC (Ov-ZBC) MOF is first synthesized by two-step reactions, and then immobilized into the tips of gelatin methacryloyl (GelMA) microneedles to obtain the double-layer GelMA/Ov-ZBC (GOZ) microneedles. Ov-ZBC MOFs demonstrate abundant Ov defects, which consequently led to a superior reactive oxygen species (ROS) production ability. Under visible light irradiation, GOZ microneedles inhibit bacterial survival and proliferation by producing ROS and releasing Zn²⁺. Additionally, they accelerate the healing of S. aureus-infected wounds through multimodal mechanisms, such as anti-inflammatory, M2 macrophage polarization, and promoting cell proliferation. In conclusion, this study not only develops an antibiotic-free theranostic platform, but also provides a proof-of-concept for modifying Zn-MOFs, thereby paving the way for their advanced biomedical applications.