Vitamin B₂ functionalized iron oxide nanozymes for mouth ulcer healing

Mouth ulcer is associated with inflammation and high risk of bacterial infection, which aggravates the patient's condition. Currently, there is no effective treatment for mouth ulcer. Herein, we report that vitamin-modified iron oxide nanoparticles improve the healing of mouth ulcer through anti-inflammation and antibacterial activities. We discovered that vitamin B₂ (VB₂) modified iron oxide nanoparticles performed enhanced peroxidase-like, catalase-like, and superoxide dismutase (SOD)-like activities, acting as typical iron oxide nanozymes (IONzymes) with triad activities. In particular, VB₂ modification significantly improved the SOD-like activity, thus providing a reactive oxygen species (ROS)-scavenging ability. Cellular antioxidant experiments showed that vitamin B₂ modified IONzymes (VB₂-IONzymes) protect human oral keratinocytes (HOK) and BALB/3T3 cells from hydrogen peroxide (H₂O₂), and these cells have high biocompatibility to eukaryotic cells. In addition, VB₂-IONzymes exerted an antibacterial activity against Streptococcus mutans, Staphylococcus aureus, and Escherichia coli. Importantly, VB₂-IONzymes accelerated the recovery of mouth ulcer and reduced the local secretion of inflammatory factors in mouse ulcer model via ROS scavenging and antibacterial activity. Taken together, our work demonstrates that vitamin B₂ modification endows iron oxide nanoparticles with enhanced enzyme-like activities and VB₂-IONzymes may be a promising reagent in the treatment of mouth ulcer because of their intrinsic anti-inflammation and antibacterial capabilities.