Microneedle Patch Loaded with Calcium Peroxide Nanoparticles for Oxygen Healing and Biofilm Inhibition in Diabetic Wound Healing

The presence of hypoxics, bacterial infection, and the creation of bacterial biofilms are significant obstacles that hinder the healing of diabetic wounds. Calcium peroxide (CaO2) can be hydrolyzed to produce oxygen (O2) and hydrogen peroxide (H2O2), resulting in the simultaneous creation of oxygen and an antimicrobial effect. However, oxygen delivery is limited by the skin and bacterial biofilm barrier. Herein, we proposed a microneedles patch loading CaO2 nanoparticles (abbreviated as CaO2 NPs@MN). The microneedles can puncture the skin and destroy the biofilm barrier. Meanwhile, upon contact with the biological fluid, the microneedles would be dissolved, and CaO2 NPs would be released into the wound site, further being hydrolyzed to O2 and H2O2 to achieve antibacterial effect and local deep oxygen delivery. Notably, in order to encapsulate CaO2 powders evenly into the microneedle tips and avoid their hydrolysis during the preparation process, we fabricated the nanoscaled CaO2 particles and encapsulated them in microneedles in an ethanol system for the first time. The in vitro experiments demonstrated that CaO2 NPs@MN possessed the desired oxygen delivery and antibacterial effect. Furthermore, the elimination of bacteria, reduction in inflammation, promotion of collagen formation, stimulation of blood vessel growth, and subsequent acceleration of wound healing were observed in in vivo experiments. In conclusion, we provided a simple process for the application of CaO2 in wound healing and also a promising strategy for infected diabetic ulcer treatment.