Temperature Distribution Research Of Biological Cells Based On Quantum Dots Near Field Optical Fiber Probe

Temperature is one of the most important characteristics of life and is the basic physical parameter to regulate physiological function.As the most basic unit of structural and functional of the organism,cellular living activities are accompanied with the generation and release of energy,and then produce the temperature variation inside the cell.Therefore,the intracellular temperature measurement is of great significance to cell vital activities research.The existing optical and non-optical cell temperature measurement methods are mainly divided into invasive and semi-invasive methods.However,these methods not only affect the cell viability,but also cannot obtain high resolution.It is an urgent need in the life science field to quest a non-invasive measurement to research the cell temperature distribution.In this thesis,a temperature measurement method based on near field optics is proposed,and the non-invasive temperature measurement probe scans sample based on the principle of atomic force microscope.At the same time,modified by quantum dots(QDs)as the nanoscale temperature sensor,the near field optical fiber probe that can be used for non-invasive cell temperature measurement is obtained.This thesis focuses on the preparation and the temperature measurement characteristics of the probe,and research of the noninvasive temperature distribution measurement method in single cell with high spatial resolution and high temperature resolution.The main research content of this paper is as follows.Firstly,the simulation model of local temperature measurement with near-field fiber probe is established by using finite element method.The optical transmission characteristics,and the temperature characteristics under the action of laser of the probe tip are studied by coupling multiple physical fields.The simulation results show that the light transmitted in the probe converges at the tip of the probe,and the local electric field is enhanced,which causes the temperature change of the probe.There is a linear relationship between the temperature and the laser power,i.e.,the higher the power is,the greater the temperature change is.At the laser power of 4 μW,the temperature of the probe is stable after 0.02 μs,and reaches thermal equilibrium with the surrounding environment in a space of 2 μm.Secondly,the aperture near-field fiber probe with QDs temperature measurement driven by tuning fork is fabricated,and its temperature characteristics are verified.After modified by QDs on the tip,the probe is combined with the tuning fork,which drives the probe to vibrate horizontally.The distance between the probe and the sample is determined by the shear-force.At the same time,the temperature sensitivity of the prepared probe is determined by temperature calibration.And the spatial resolution is indicated by scan the standard sample using the probe.Finally,the temperature distribution of human astroblastoma cells(U87MG)treated with different methods are imaged and the results are compared.At first,using the near-field optical fiber coated with quantum dots proposed in the thesis,the temperature difference of fixed cell with gold nanoparticles,which indicated the feasibility of the method for cell temperature measurement.Then,using different methods,the temperature difference of the fixed cells is measured.The difference of results shows the reliability of the method.Finally,using the method proposed in the thesis,the temperature difference of living cell is measured.The results show that the non-invasive temperature measurement are more close to the real temperature of the cell,and the temperature measurement process has anti-interference,so the measured results are more authentic.