Research On Non-thermal Effects Of Cells Based On Terahertz And Optical Laser

The research and application of electromagnetic waves in the medical field has shown the great potential and value of this approach in this field,where the study of biological effects based on terahertz waves and optical lasers has attracted the attention of scholars from various countries.In this thesis,the non-thermal biological effects induced by terahertz wave and optical laser radiation on cells are studied from the cellular level.Initially,the cell model was built by using the finite element method,and the simulation result revealed that the electric field of terahertz wave could cause a large potential difference on both sides of the cell membrane,which provided a basis for subsequent experiments.Then,the single-frequency and high-power THz free electron laser(THZ-FEL)produced by China Academy of Engineering Physics THz Free Electron Laser(CAEP THz FEL)device was used,and the radiating cells optical path and biological experiment platform of THz wave was constructed to radiate mouse melanoma cells(B16 cells)and rat pheochromocytoma cells(PC-12 cells).The results showed that after THz-FEL radiation,the apoptosis rate of B16 and PC-12 cells increased 4-fold and3-fold,respectively.Combined with the literature,it was found that THz-FEL may cause perforation of cellular biofilm,interfere with intracellular substance synthesis process,thus disrupting the intracellular homeostatic environment and non-thermally inducing apoptosis.On this basis,the optical path and experimental platform of THz-FEL radiation on mouse tumor tissues were built in this thesis,and THz-FEL non-thermal tumor ablation experiment was carried out.The result demonstrated that THz-FEL radiation might enhance the immune function of mice against melanoma while inducing the apoptosis of mouse melanoma tissue cells through non-thermal effect.Thus,non-thermal ablation of tumor tissue can be achieved.Next,the biological effects of continuous wave laser and femtosecond pulse laser irradiation on cells were studied.In the study of PC-12 cells irradiated by continuous wave laser,it was found that when the temperature of cell culture medium was slightly increased to 39? due to low power and short-term radiation,the activity of some enzymes in cells might be enhanced,leading to the enhancement of cell proliferation activity,and the OD value of the experimental group was significantly greater than that of the control group.However,high power and long-term radiation caused high temperature in cell culture medium(43?)and induced cell apoptosis,which may be caused by excessive accumulation of reactive oxygen species(ROS)in cells under high temperature for a long time,which damaged cell contents and opened the mitochondrial apoptosis pathway,and the apoptosis rate in the experimental group was about 1.4 times higher than that in the control group.In femtosecond pulse laser experiments,the result showed that when the numerical aperture was small,the light breakdown threshold of cell contents might be increased,and the contents of Mouse Embryonic Fibroblasts(MEF cells)could not be damaged,resulting in insignificant autophagy.In summary,this thesis investigated the cellular biological effects of terahertz and optical laser,respectively.It was found that THz-FEL might induce apoptosis by disrupting cell structure and interfering with cell substance synthesis,continuous wave laser radiation induced intracellular ROS accumulation and thus induces apoptosis,and femtosecond pulsed laser is difficult to induce apoptosis under smaller numerical aperture lens.Those findings provide new ideas for potential applications of terahertz and optical lasers in the biomedical field.