Preparation Of A Dual Photothermal-photodynamic Antibacterial Molybdenum Disulfide Drug Delivery System And Its Promotion Of Wound Healing

Slow wound healing due to bacterial infections has always been a problem in public health,particularly with regard to bacterial resistance following antibiotic treatment.There is therefore an urgent need to change traditional treatment methods and develop new ones.Photodynamic therapy（PDT）and photothermal therapy（PTT）have received much attention as non-specific antimicrobial strategies that are less likely to trigger bacterial resistance;PDT exhibits significant antimicrobial properties by using cytotoxic reactive oxygen species（ROS）produced by photosensitizers under visible or UV light irradiation,and PTT inhibits bacterial growth by absorbing light energy into heat under visible or UV light irradiation.These two methods are less likely to cause bacterial resistance and have fewer side effects due to their unique antibacterial mechanisms.Thus,in this study,MoS₂,which has good photothermal effect,was used as the base material to prepare antibacterial hydrogel nanomaterials with dual photothermal/photodynamic properties for bacterial infection treatment and promotion of wound healing,and the research content and findings are as follows.（1）MoS₂ nanosheets were synthesized by liquid-phase sonication,and 5（6）-isothiocyanate fluorescein（FITC）-labelled Van was loaded on the surface of MoS₂ nanosheets by electrostatic adsorption,and MoS₂-Van-FITC@CS composite hydrogel dressings with good photothermal conversion and antibacterial properties were prepared by chitosan（CS）hydrogel wrapping.MoS₂-Van-FITC@CS addresses the shortcomings of the MoS₂ photothermal effective radius and improves the ability to treat wound infections.SEM results showed that the average thickness of MoS₂nanosheets was about 30 nm.UV,FT-IR and Zeta characterization experiments verified the successful synthesis of MoS₂-Van-FITC@CS.Photothermal characterisation yielded a photothermal conversion efficiency of 52%for MoS₂,and cellular uptake experiments verified the active capture of Staphylococcus aureus by Van.In vitro inhibition experiments showed that the survival rate of S.aureus was only 5.49%after NIR light irradiation of the composite（100μg/m L）at 808 nm（1.5W/cm²,5 min）,which significantly improved the antibacterial activity of MoS₂.Experiments on mouse wounds showed that the relative area of the wounds was reduced to 21%after 8 days of nanomaterial treatment,which accelerated the wound healing.（2）In order to further improve the surface area,photothermal conversion efficiency and active oxygen production capacity of MoS₂nanomaterials,MoS₂ nanospheres of uniform size were synthesized by hydrothermal method,ionic liquid（IL）was used instead of Van to enrich bacteria,reducing the use of antibiotics,Ce6 was introduced to improve the active oxygen production capacity of the material,and chitosan（CS）hydrogel was used to wrap the composite nanomaterial MoS₂-Ce6-IL.The SEM results showed that the MoS₂-Ce6-IL nanospheres were approximately 220 nm in size,and the successful synthesis was verified by UV,FT-IR and Zeta characterisation.The photothermal photodynamic characterisation showed that MoS₂-Ce6-IL has a photothermal conversion efficiency of 54%and a good ability to generate reactive oxygen species.The in vitro antibacterial activity of MoS₂-Ce6-IL was shown to be excellent,with 96.8%inhibition of Staphylococcus aureus and 94.4%inhibition of Escherichia coli at a concentration of 150μg/m L.Transcriptomic analysis of MoS₂-Ce6-IL affected bacterial metabolic pathways,thereby inhibiting bacterial growth.Mouse trauma experiments demonstrated accelerated wound healing by treatment with a reduction in relative surface volume to 23%.In summary,this paper uses MoS₂ as the base nanomaterial carrier,combined with photothermal and photodynamic therapy to achieve broad-spectrum antimicrobial effects,and the MoS₂ composite hydrogel dressing improves the wound environment and promotes wound healing.This study lays the foundation for the application of MoS₂ composite nano-hydrogel as a novel antibacterial wound dressing,opening up its wide application in wound healing and bacterial infection.