Construction Of Ratio Fluorescence Nanometer Thermometer And Its Application In Tumor Cell Magnetic Hyperthermia

As the most basic parameter of a living body,temperature affects every biochemical reaction,enzyme activity,material transportation,cell division and energy metabolism in living cells.Based on magnetic nanoparticle-mediated tumor magnetothermal therapy,the main way to kill cancer cells is to use local temperature rise to destroy the physiological process of cancer cells and further promote the apoptosis of cancer cells.Exploring the temperature distribution in the cell and understanding the temperature change in the intracellular area is an important physiological parameter index for analyzing the effect of the treatment of tumor cells based on the magnetocaloric effect.Therefore,the realization of high-sensitivity and high-resolution temperature measurement in tumor cells,especially temperature measurement on the scale of subcellular organelles,is a very meaningful research work.In response to this need,this thesis researched and developed a molecule based on aggregation-induced luminescence（AIE）,w hic h was surface-modified and combined with fluorescent quantum dots to construct a ratio fluorescent nanometer thermometer.Characterization methods such as morphology,structure,optical and bio-fluorescence imaging have verified that the nanometer thermometer is controllable and has the function of measuring temperature in cancer cells.The contents and specific contents of this article are as follows:It briefly introduces the principle of the basic method of magnetothermal treatment of tumor cells,as well as the important significance of temperature as a physical parameter in magneto-hyperthermia.The current existing intracellular temperature measurement techniques and the latest research progress of nanothermometers are reviewed.The current status of the application of fluorescent probes based on aggregation-induced luminescence properties in organisms and the research status of temperature-sensitive materials based on aggregation-induced luminescence properties are introduced in detail.The ratio fluorescent nanometer thermometer（TBTD@QDs-PEG）was prepared in a controllable manner.First,mercaptopropionic acid-modified cadmium selenide zinc sulfide fluorescent quantum dots（QDs）and 2 KDa amino-modified phospholipid polyethylene glycol（PEG）are connected by amide condensation reaction,and then they are connected with PEG-modified tetraphenylethene-based tetracationic dicyclophane（TBTD@PEG）is wrapped and combined by hydrophobic interaction to form a TBTD@QDs-PEG ratio fluorescent nanometer thermometer with a hydrated particle size of about 82 nm.Through the intensity ratio of the two fluorescence emission peaks at 460 nm and 556 nm,a standard curve of temperature with respect to I₄₆₀/I₅₅₆ value is obtained.The temperature measurement function is realized within the range of 25℃to 60℃,and the resolution can reach 3.031%·℃^-1.The synthetically constructed nanometer thermometer was used to monitor the temperature changes in tumor cells in real time during the magneto-caloric process.A human breast cancer cell line（MCF-7）was selected for subculture,incubated with TBTD@QDs-PEG nanometer thermometer for 8 hours,and incubated with magnetic iron oxide nanoparticles for 8 hours.Observed under a laser confocal microscope.After endocytosis,the magnetic iron oxide nanoparticles and the nanometer thermometer are in the intracellular lysosome at the same time.Within 15 minutes of applying an alternating magnetic field with a magnetic induction intensity of 25 m T,it can be observed that the fluorescence intensity of the intracellular nanothermometer has been significantly reduced.Collect the fluorescence intensity data at 460 nm and 556 nm.According to the above temperature measurement standard curve,the temperature of intracellular lysosome can be increased from room temperature to 45℃on average under alternating magnetic field,and the local temperature can be increased to 47℃.the above.It is intuitively and clearly confirmed that the heat generation and temperature rise of magnetic nanoparticles in the intracellular nanometer range in magnetic hyperthermia has important reference significance for further explaining the basic principles of magnetic hyperthermia.