Construction Of A New BODIPY Fluorescent Probe Substituted At The Meso Position And Its Application In Viscosity And Hydrogen Peroxide Bioimagin

Small organic molecular fluorescence probes are widely used as an effective detection tool for biomass detection,cell imaging,in vivo biochemical reaction process tracking and disease biomarker monitoring.Viscosity and hydrogen peroxide play a key role in bioregulation and biophysiological processes.Boron dipyrromethenes（BODIPYs）are widely used for the detection of viscosity and reactive oxygen species with unique advantages,such as ease of modification,high fluorescence quantum yield and low toxicity to organisms.Therefore,this thesis proposes the synthesis of novel meso-substituted BODIPY fluorescent probes to investigate their fluorescence properties and bio-imaging potential for viscosity and hydrogen peroxide.（1）We reported for the first time two new monostyryl BODIPY 4 and 6 with a rotating CF₃ group in the meso position and a triphenylphosphine（4）or morpholine（6）target group that can be successfully used as highly sensitive,near-infrared emitting fluorescent probes for imaging the cellular viscosity of mitochondria or lysosomes.These probes exhibit intense NIR fluorescence at 657 nm in high viscosity glycerol and show a good linear relationship between fluorescence intensity（log I）and viscosity（logη）.Probes 4 and 6 have low cytotoxicity and good targeting of mitochondrial or lysosomal functions.These two new BODIPY-based fluorescent rotors provide a new strategy for the development of organelle-specific near-infrared emitting fluorescent probes for cell viscosity,which may help explore the relationship with various viscosity-related diseases.（2）We rationally designed and successfully synthesized a novel meso C=C double bond BODIPY fluorescent“turn-on”and ratiometric molecular probe 8.The probe is highly selective and sensitive,with a“turn-on”fluorescence at 540 nm and a proportional change between 506nm and 540 nm.Exposure to hydrogen peroxide resulted in strong fluorescence emission at 540nm with an increase in fluorescence quantum yield from 0.009 to 0.13.Fluorescence at 540 nm increased linearly over a range of 2 to 10μM of hydrogen peroxide and the calculated detection limit for hydrogen peroxide is 31 n M.The probe is suitable for p H 6-10 and can also be applied to RAW264.7 and HEK 293 cells to detect exogenous and endogenous hydrogen peroxide,providing a new method for detecting cellular hydrogen peroxide.（3）We have successfully designed and synthesised new fluorescent probes 9,10 and 11for BODIPY with a C=C double bond in the meso position,which show weak fluorescence at low viscosity and strong fluorescence with increasing viscosity and have good selectivity for detection of cell viscosity.Probe 9 fluoresces weakly at 561 nm at low viscosity and becomes progressively strongly fluorescent as the glycerol content increases to 60%.The fluorescence intensity of 9 showed good linearity with R² of 98%and 99%for viscosity in the 0-60%glycerol content and 60-100%viscous mixture,respectively,and the fluorescence quantum yield increased from 0 to 0.019 by change from water to glycerol.Probes 10 and 11 have similar properties to probe 9,with fluorescence quantum yields increasing from 0.007 and 0.008 to0.016 and 0.012 by change from water to glycerol,respectively,with a 2.3-and 1.5-fold increase in fluorescence,respectively.Probes 9 and 10 can also be used to detect cellular viscosity in SH-SY5Y cells,providing a new strategy for detecting cellular viscosity.