Molybdenum Carbide Nanospheres For Photothermal Therapy And Anti-Infective Therapy

In recent years,cancer and pathogenic microbial infections have become an important cause of threats to human health,as the number of deaths has increased year by year.Traditional treatments for both conditions have certain limitations.Therefore,exploring new treatment strategies has become a top priority.As an emerging treatment,phototherapy can effectively cope with tumor or bacterial infections with little side effects and does not cause body resistance.In this thesis,photoactive molybdenum carbide?Mo₂C?in the MXene family is used as a nano-diagnostic agent,and its photothermal and photodynamic effects are used to achieve phototherapy for tumors and antibacterial healing of infected wounds.The precursor was prepared by liquid phase synthesis using molybdenum phosphate/pyrrole as raw material,and then the carbon monoxide nanospheres?50 nm?with uniform size were obtained by high temperature carbonization,which successfully solved the dilemma of the traditional stripping method that could not obtain the nanometer dimension MXene.The molybdenum carbide nanoparticle obtained in this paper satisfies both the microstructure of in vivo delivery and the MXene characteristic of near-infrared full-spectrum absorption.In addition,the optical absorption mechanism and electronic energy level structure of Mo₂C were studied by theoretical simulation system.Firstly,the single substance nano-Mo₂C is used as a multi-functional diagnosis and treatment platform,which can simultaneously mediate the characteristics of photothermal and photoacoustic free radicals under near-infrared light irradiation,realizing the synergistic effect on tumors in vivo and in vitro,and found Mo₂C in the research.Nanosphere-mediated synergistic treatment is significantly better than single treatment.In addition,Mo₂C nanospheres can also be used as contrast agents to achieve integration of diagnosis and treatment in the anti-tumor process.The excellent photothermal effect of Mo₂C nanospheres and its high effective atomic number make it have good photoacoustic imaging and CT imaging effects.In this thesis,the process of solid tumor ablation was studied by B-ultrasound and magnetic resonance imaging techniques,and it was found to satisfy the typical liquefaction necrosis process.At the same time,histopathological examination and blood analysis methods have determined that Mo₂C nanosphere-mediated phototherapy has good biocompatibility,which is inseparable from its good metabolism.Experiments have shown that Mo₂C can be decomposed in body fluids and blood,and finally metabolized in vitro in the form of feces and urine.In the wound healing and anti-infective treatment experiment,this paper found that Mo₂C nanospheres have the characteristics of catalase in addition to the phototherapy effect.The effect of enzyme-like enzyme activity depends on temperature,material concentration,pH value and H₂O₂ solution concentration.The activity promotes the decomposition of a low concentration of H₂O₂ solution to produce hydroxyl radicals.Using the plate counting method and fluorescent staining method to determine the effect of Mo₂C nanospheres in the low concentration of H₂O₂ solution to kill E.coli under near-infrared light-induced irradiation is better than other experimental methods,indicating that the introduction of enzyme-like properties and phototherapy synergistically in anti-bacterial infection.The results are remarkable.In the mouse model,it was shown that the wound healing rate of the mouse was accelerated after the introduction of synergistic light therapy,which shortened the wound healing cycle.In summary,phototherapy can play an effective role in anti-tumor and anti-infective fields.At the same time,Mo₂C nanospheres are excellent photoactive materials,which can simultaneously achieve phototherapy,multiple imaging,enzyme-catalyzed,active degradation,etc.