Nanofibrous Dressing with Nanocomposite Monoporous Microspheres for Chemodynamic Antibacterial Therapy and Wound Healing

The excessive use of antibiotics and consequent bacterial resistance have emerged as crucial public safety challenges for humanity. As a promising antibacterial treatment, using reactive oxygen species (ROS) can effectively address this problem and has the advantages of being highly efficient and having low toxicity. Herein, electrospinning and electrospraying were employed to fabricate magnesium oxide (MgO)-based nanoparticle composited polycaprolactone (PCL) nanofibrous dressings for the chemodynamic treatment of bacteria-infected wounds. By utilizing electrospraying, erythrocyte-like monoporous PCL microspheres incorporating silver (Ag)- and copper (Cu)-doped MgO nanoparticles were generated, and the unique microsphere-filament structure enabled efficient anchoring on nanofibers. The composite dressings produced high levels of ROS, as confirmed by the 2,7-dichloriflurescin fluorescent probe. The sustained generation of ROS resulted in efficient glutathione oxidation and a remarkable bacterial killing rate of approximately 99% against Staphylococcus aureus (S. aureus). These dressings were found to be effective at treating externally infected wounds. The unique properties of these composite nanofibrous dressings suggest great potential for their use in the medical treatment of bacteria-infected injuries.

Enhanced anti-Escherichia coli properties of Fe-doping in MgO nanoparticles

Hetero-elements doping is an effective way to modify the composition and nanostructure of metal oxides. These modifications could lead to changes in physical and chemical properties correspondingly. In this study, Fe-doped MgO nanoparticles (NPs) were synthesized by simple calcination method in air. The antibacterial activity of MgO NPs against Escherichia coli (E. coli, ATCC 25922) was significantly improved as shown by the bactericidal efficacy test results. According to X-ray diffraction (XRD) results, Fe was successfully doped into MgO lattice and mainly adopted interstitial doping. The Fe-doping led to increased oxygen vacancies and OA content (from 13.5% to 41.3%) on MgO surface, which may have facilitated the reactive oxygen species (ROS) generation and bacteria death. The wrinkled and sunken E. coli surface after contact with Fe-doped MgO NPs also confirmed the existence of adsorption damage mechanism. Thus, the antibacterial activity enhancement against E. coli was originated from the synergistic effect of increased ROS concentration and the interaction with Fe-doped MgO NPs.