Design,Synthesis And Bioimaging Applications Of Mitochondrial-Targeted Molecular Rotor Viscosity Fluorescent Probe

The demand of medical for research in cell-level microenvironment is increasing with the deepening of people’s exploration of the world,and the value of viscosity in the research of microenvironment is also being high more and more in scholar.Viscosity plays an important role in our daily biological and chemical activities.This function including diffuse and transport nutrients into and out of cells,and be the potential biomarker in a variety of diseases.Mitochondria are one of important organelles in cell,the important of monitoring whether microenvironment of mitochondria is stable is even more self-evident.Some common diseases such as diabetes,hyperlipidemia,Alzheimer’s disease and cancer often accompanied by abnormal changes in the viscosity of the mitochondria.If we can detect and monitor these abnormal changes early,we will make better accurate judgments for prevention and treatment.Fortunately,many mitochondrial-targeted probes have been reports for detecting viscosity in recent years.Mitochondrial-targeted viscosity-sensitive probes have shown good application prospects in the level of cell and live,some of these probes have shown good properties,but the number of mitochondrial-targeted viscosity-sensitive rotor-type probes that could be chose are still not enough.In order to develop more mitochondrial-targeted viscosity-sensitive molecular rotor fluorescent probe that equip with better performance,we have designed and synthesized two kinds of mitochondrial-targeted viscosity-sensitive molecular rotor fluorescent probe in this paper.The structure of one from this designed by imidazole’s derivative and indole’s salt,the structure of other one based on phenol dihydroxanthene and quinoline’s salt in this paper,we have conducted in-depth research on its spectral characteristics and biological research.In chapter 2,we have designed and synthesized a mitochondrial-targeted viscosity-sensitive molecular rotor fluorescent probe named RM-V,and we studied the spectrum and biological applications from RM-V.The structure of RM-V based on D-π-A configuration,have a large conjugated system and composed with imidazole’s derivatives as electron-donating groups and indole’s salts as electron-withdrawing groups.With skillfully modified in imidazole,the design stronger electron-donating groups ability,thereby stronger the twisted intramolecular charge transfer effect.When the probe was excited by 530 nm excitation light,it will emit strong fluorescence at 575 nm in spectrum under viscous conditions.The characteristic fluorescence signal will gradually decrease with solution was changed to a low viscosity.When the viscosity was changed from 2.1 cp to 1596 cp,the fluorescence intensity increased by 7.2 times.In biological experiments,the co-localization experiment with Mito Tracker^TM Green FM showed that RM-V has a high degree of mitochondrial targeting and can also successfully monitor the abnormal viscosity change in live cell mitochondria treated by ion inhibitors.In chapter 3,we explore more in-depth research,using the modified phenol dihydroxanthene（HD dye）as a fluorophore,combined with quinoline’s salt to help probe improve the ability to dissolve in water,finally got a near-infrared emission viscosity-sensitive probe NI-VD with large Stokes-shift.Due to the TICT effect,molecular rotor be inhibited in high-viscosity solution,molecule enters the TICT state and emits strong fluorescence.After testing and analysis,NI-VD fluorescence intensity and fluorescence lifetime shown a good linear relationship with viscosity.In biological experiments,we used characteristic that mitochondrial targeting,specific response under complex conditions,and good biocompatibility from NI-VD,the kidney cells of the experimental group and the control group were fluorescently labeled by NI-VD.It was successfully proved that there was a significant difference in the viscosity of mitochondria in the renal tubular epithelial cells of diabetic nephropathy with the normal one,after mark by NI-VD the difference was visualized though fluorescence imaging and in vivo imaging.