Experimental Study Of Combined Photothermal-chemodynamic Treatment Of Magnetic Fe-doped ZIF In Oral And Maxillofacial Infections

Background and Objectives:Oral and maxillofacial infections are common diseases with unique anatomic and physiological characteristics.If the treatment of infected wounds is not timely,it may lead to maxillofacial cellulitis,mandibular osteomyelitis,and other serious illnesses.Debridement of wound sites in combination with antibiotic use is the main treatment method for oral and maxillofacial infections.However,the widespread use of antibiotics has led to the emergence of multidrug-resistant strains,making the removal of biofilms an important issue in the treatment of such infections.Photodynamic therapy（such as photodynamic therapy,photothermal therapy,etc.）has become more prevalent in recent years because of their non-invasive nature,site selectivity,and lack of an intrinsic resistance mechanism.The goal of this study is to develop a degradable magnetic antibacterial material that can be used to treat bacterial biofilms in oral and maxillofacial infections for low-toxic and high-efficiency anti-biofilm infections in soft tissue.Methods:1.Synthesize magnetic nanoparticle antibacterial materials with Fe₃O₄-based nanoparticles,which have excellent photothermal properties.In this study,ZIF-L-Fe magnetic nanoparticles loaded with Fe nanoparticles using ZIF-L as a carrier were simply and rapidly synthesized.2.Analyze the surface or physical properties of materials using scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,energy dispersive X-ray spectroscopy（EDS）,particle size analyzer,potential analyzer,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,Electron spin resonance（ESR）spectrometer,and inductively coupled plasma emission spectrometer（ICP-OES）.3.Conduct bacterial killing experiments with crystal violet staining and SEM to analyze the killing effect of material components on bacteria and bacterial biofilms under light activation.4.Use a hemolysis test and CCK-8 test to determine the biocompatibility of the material to blood and normal tissue cells.5.Establish an injury infection model in animals,and use ZIF-L-Fe to treat mouse skin wound infection.Results:1.The synthetic ZIF-L-Fe is a nanoscale particle with ZIF-L as a carrier load,a crystal simulation of Fe₃O₄,and a peak similar to ZIF-L.The particle size is 400-600 nm,has a positive charge,and contains Fe²⁺,Fe³⁺,and Zn²⁺electronic energy spectra.There is the generation of·OH.The proportion of Fe elements in ZIF-L-Fe is about 59%.2.The antibacterial concentrations of ZIF-L-Fe against Escherichia coli（E.coli）and methicillin-resistant Staphylococcus aureus（MRSA）were 125μg m L^–1 and 200μg m L^–1,respectively.The crystal violet staining observation of the biofilm killing effect showed that ZIF-L-Fe had obvious anti-biofilm effects under the conditions of light,hydrogen peroxide（H₂O₂）,and magnetic field.SEM observed the state of biofilm retention under various conditions,and the results showed that ZIF-L-Fe had very little bacterial retention under the conditions of light,hydrogen peroxide,and magnetic field,indicating significant anti-biofilm performance.3.Hemolysis and CCK-8 tests showed that ZIF-L-Fe had no obvious cytotoxicity and good biocompatibility.4.In vivo experiments demonstrated that ZIF-L-Fe was effective at treating bacterial infection and promoting wound healing.Conclusion:The study demonstrated the successful preparation of photoresponsive antimicrobial material.The synthesized ZIF-L-Fe had a flower-like cluster structure with sharp edges,which prevented the stacking of two-dimensional ZIF leaves and improved the dispersion of Fe nanoparticles.Additionally,the catalytic and photothermal properties of ZIF-L-Fe destroyed the biofilm structure under multiple actions,allowing for the effective treatment of anti-biofilm infections in wound infections caused by bacterial biofilms.