Research On Synergistic Bacteriostasis Of Low-Power Near-Infrared Photothermal Conversion Based On Two-Dimensional Nanosheets

As the abuse of antibiotics has led to the raging of multi-drug resistant bacteria,the development of new methods to treat bacterial infections is imminent.The photothermal/photodynamic(PTT/PDT)coordinated strategy has shown broad prospects in combating multi-drug resistant bacteria.However,two laser sources with different wavelengths need to be irradiated sequentially or a single high-power laser is irradiated to activate PTT/PDT.The power density of most lasers far exceeds the safety standards for laser use.In fact,for the anti-infective treatment of multi-drug resistant bacteria,building a safe PTT/PDT platform with a single low-power laser is still an challenge.Therefore,this study developed two effective antibacterial agents based on acetylcholine-modified copper sulfide nanosheets and indocyanine green functionalized Trimanganese tetraoxide nanosheets,which can achieve low-power PTT/PDT has synergistic antibacterial effect.The details of the researches are as follows:Part ? Low-power photothermal/photodynamic synergistic targeted therapy of lung/skin bacterial infections by acetylcholine modified copper sulfide nanosheetsIn order to achieve low-power photothermal/photodynamic synergistic antibacterial,a new photothermal agent-acetylcholine-copper sulfide nanosheets(Ach-Cu S NSs)was synthesized.Acetylcholine is used to modify copper sulfide nanosheets so that they can be targeted to the surface of bacteria,and due to the two-dimensional sheet structure of Ach-Cu S NSs,it is easy to adhere to the surface of bacteria.Under laser irradiation,a single-wavelength and low-power PTT/PDT synergistic antibacterial effect is achieved through the generation of close-range high heat and a large amount of reactive oxygen species(O₂^-·,¹O₂,·OH).Ach-Cu S NSs has strong antibacterial activity against a variety of pathogenic bacteria including MRSA,can inhibit the formation of biofilm,and can reduce the formed biofilm content to 38.9%under laser irradiation.Because Ach-Cu S NSs can cure bacterial pneumonia and subcutaneous abscess in mice caused by MRSA infection,,making it a potential antibacterial drug.Part ? Photothermal/photodynamic synergistic treatment of multi-drug resistant bacteria infection by functionalized Trimanganese tetraoxide nanosheetsBased on the indocyanine green functionalized trimanganese tetraoxide hexagonal nanosheets(Mn₃O₄HNSs@ICG),we have developed a platform that can realize low-power PTT/PDT synergistic antibacterial in a short time.With the advantages of this nanomaterial,the platform can effectively convert near-infrared light to high temperature(with a photothermal conversion efficiency of 67.5%)under the irradiation of a single 808 nm laser with a power density as low as 0.33 W/cm²,and at the same time catalyze the formation of three kind of ROS(¹O₂,O₂^-·and·OH).The sheet-like structure with a rough surface makes this nanomaterial tend to adhere to the surface of bacteria and destroy its membrane system under near-infrared radiation.By combining physicochemical antibacterial mechanisms,the platform shows excellent therapeutic effects on wound infection models induced by MRSA in vivo.Importantly,both in vitro and in vivo toxicity evaluations have proved the superior biological safety of this nano-platform and will not damage the skin under long-term irradiation.In summary,the photosensitive Mn₃O₄nanosheets with a rough surface that can be activated by a single 808 nm laser with low power density provide a multifunctional,effective and safe platform for the realization of PTT/PDT synergistic antibacterial and wound treatment,Which is promising to apply in clinical anti-infective therapeutics.