Cellular Location Imaging With Different Mechanisms

Mechanisms of physiological and pathological changes are very important for the prevention and diagnosis of diseases.Cells,as the basic structural and functional units of living organisms,participate in various physiological processes.Accurately monitoring the formation process and microenvironment changes in cells is the basis for understanding the physiological and pathological changes.Due to the relatively low concentration of intracellular analytes and complicated envirounment in vivo,imaging tools with high sensitivity are urgently needed.Traditional imaging methods are lack of specificity and sensitivity,such as computed tomography,magnetic resonance imaging and ultrasound.Positron emission tomography is highly sensitive,however,limited by the strict safety regulation for radioactive compounds.Optical imaging such as fluorescence and bioluminescence imaging has resulted in accurate diagnosis through non-invasive,real-time and high-resolution imaging.Therefore,localization by fluorescence imaging has realized the visualization of specific organelles or whole living cell,providing a powerful tool for the accurate prevention and diagnosis of diseases.Following is the main content of this thesis:(1)Using the unique physical properties of specific organelles to locate and monitor the formation process of lipid dropletsAs an important physical parameter,polarity plays an important role in the change of cell physiological process.Compared to proteins,nucleic acids and carbohydrates,the lipid structures usually have extremely low polarity.However,fluorescent dyes(polarization-sensitive fluorescent probes)whose emission spectra change significantly with polarity can locate lipid substances.After electron excitation,the dipole moment of polarization-sensitive fluorescent probe changes obviously,which affects the shift of emission wavelength.By collecting emitted fluorescence at different wavelengths,organelles of different polarity can be clearly located.(2)Covalently bind specific targeted proteins with fluorescent chromophors for localization organellesReal-time dynamic analysis of specific proteins in living cells has attracted extensive attentions,recently.SNAP-tag can rapidly and specifically reacted with benzylguanine derivatives through covalent bonds both in vivo and in vitro.We used genetic engineering to fuse the SNAP-tag protein into different organelles.The designed fluorescent molecules with BG groups were brought into the specific organelles through specific binding of the BG group in fluorescent probe and SNAP-tag protein to achieve the localization and visualization of desired organelles.(3)localize tumors through monitoring specific enzymes by fluorescent probes with desired targeting groupsProtease,as an important diagnostic biomarker for many diseases,plays an important role in regulating various metabolic processes.In vivo protease monitoring is important for biological,medical and related research,especially in tumors.?-glutamyl transpeptidase(GGT)is one of the most important proteases overexpressed in tumors.Therefore,accurate recognition of GGT can be used to locate tumors.Fluorescent probe with specific recognition moiety through the amide bond is colorless with barely fluorescent emission.After exissive GGT in tumors breaks the amide bond and releases the fluorescence molecule,strong fluorescence are emitted.With the designed probe,we can accurately target tumors in vivo.