Optical Properties Of Molybdenum Disulfide With Few Layers And Application Of Piezoelectric Catalysis In Tumor Treatment

Cancer is a major disease in clinical medicine,which has seriously threatened human life safety and hindered social development.Clinical medicine urgently looks forward to the development of non-invasive or minimally invasive treatment to avoid unnecessary painful experience and serious side effects of traditional treatment.In recent years,the development of efficient inorganic nano materials to kill tumor cells by physical means has become an important research direction of tumor treatment.Such as efficient photothermal conversion efficiency,photocatalysis and acoustic power to produce reactive oxygen species.Photothermal therapy is a typical physical method to treat tumors.It has been widely studied because it is non-toxic and harmless and has little side effects on human body.Recently,piezoelectric catalytic therapy has been widely studied because of its safe and efficient characteristics similar to acoustic dynamics.Similar to photodynamic and acoustic dynamics,piezoelectric catalytic therapy uses ultrasound as excitation energy to produce reactive oxygen species to kill tumor cells.In this paper,molybdenum disulfide with few layers is synthesized by a simple method.MoS2 with odd layers has unique piezoelectric effect due to its asymmetric structure.In the research,we have proved that as a piezoelectric material,low-layer molybdenum disulfide can deform under the activation of external ultrasound,resulting in polarization,resulting in the separation of electrons and holes in the material,so as to form an internal electric field.Due to the internal electric field,the separated electrons and holes migrate reversely to the MoS2 surface,and the surface potential imbalance promotes the redox reaction on the MoS2 surface to produce reactive oxygen species.The main research contents of this paper are as follows:（1）Few-layer MoS2 structure was synthesized by lithium intercalation stripping molybdenum disulfide.Its microstructure and physical properties were studied by characterization.The element composition and crystal form of the material are determined by TEM,XRD and Raman,and the few layer structure of the material can be confirmed.It is confirmed that the material has good light absorption performance in the near-infrared region by UV absorption,which shows that it has good photothermal conversion efficiency.The photothermal conversion efficiency is further confirmed by heating it with a 1064 laser and recording the temperature change with a photothermal camera.In order to verify the photoacoustic imaging ability of the material,and the photoacoustic imager was used to prove that the low-layer MoS2 has excellent photoacoustic imaging ability at the same time.The material is modified to improve its biocompatibility,and relevant experiments are carried out in vitro.The material is co incubated with tumor cells to determine the toxicity of the material.After irradiation with 1064 nm laser,it can be found that tumor cells will be inactivated on a large scale.（2）At present,the generation of reactive oxygen species is mainly verified by electron spin and chemiluminescence.Diphenyl isobenzofuran（DPBF）aqueous solution has a very obvious UV absorption peak at 420 nm.DPBF will react with singlet oxygen,resulting in the decrease of UV absorption peak.Experiments show that after mixing a few layers of MoS2 aqueous solution with DPBF,the UV absorption peak of DPBF at 420 nm can be observed to decrease significantly.2,2,6,6tetramethylpiperidine oxide（TEMP）.is a singlet oxygen spin trapping agent.Combined with ERP spectroscopy technology,it can be used to detect the singlet oxygen produced by the system.In order to further explain that the few layer MoS2 aqueous solution can produce singlet oxygen under ultrasonic conditions,tempo is added to the few layer MoS2 aqueous solution for ultrasonic,The waveform obtained by electron spin resonance spectroscopy confirmed that singlet oxygen was produced.Finally,it is applied to cell and animal experiments to verify the photothermal and piezoelectric catalysis of Few-layer MoS2.