Design,Synthesis And Cell Imaging Research Of Novel Molecular Fluorescence Probe

Chapter 1:This chapter explained the development and advantages of fluorometry.The principles of fluorescence,the composition and classification of fluorescent probes and the influencing infactors of the fluorescence properties are introduced in short.Also,the mechanism of fluorescence probes and the research progress in recent years are reviewed.Chapter 2:A thiazole-based ratiometricemission fluorescent probe BTDB has been synthesized and its photophysical propertiesare investigated as a function of p H.This probe exhibits ratiometricresponse(F₄₂₅/F₅₉₅)to p H and can detect p H changes in the extreme acidity range of 2.3–4.0 with a p K_aof 2.34.It is highly significant that BTDB displays a large Stokes shift of177 nm under acidic conditions,which can reduce the excitation interference.Moreover,other favorable features of BTDB include good reversibility,high selectivity,and excellent cell membrane permeability,all of which are favorable for intracellular p H imaging.Application of BTDB in Hela cells and E.coli cells are also achieved successfully,indicating that BTDB can be employed as a ratiometric fluorescent p H probe for imaging p H fluctuations in the physiological p H with excellent lysosomal targeting ability,especially under extreme-acidity condition in bacteria.Thus,it is anticipate for BTDB and its derivatives would be potential application for cell imaging in the biomedical and biological fields,and the development of extreme acidic p H probe would also promote biology study on special bio-logical systems.Chapter 3:A novel ratiometric TP probe(DNEPI)was developed for two-photon excited cellular imaging of mitochondrial cysteine on the basis of the strong nucleophilic substitution of Cys promoting the cleavage of the sulfonic acid ester bond of DNEPI.The probe exhibited high selectivity toward Cys overother biothiols(including Hcy and GSH).More importantly,the probe could detect Cys with a fast response time(within 2 min)and the detection limit was quantitatively calculated as 0.29?M.Furthermore,this probe also displayed low cytotoxicity and excellent biocompatibility,which were favorable for intracellular imaging.Subsequently,application of DNEPI to Cys imaging in live cells was successfully achieved by twophoton fluorescence microscopy,indicating that the probe had significant mitochondrial-targeting ability and could be used to monitor Cys concentration change in live cells.Therefore,this ratiometric two-photon fluorescent sensing probe proposed here has great potential for application to investigating and monitoring changes in intracellular Cys levels in living biological systems with negligible interference from other biological thiols.Chapter 4:The Rhodol dye structural unit always be obtained by hybridization based on the structure of luciferin and rhodamine dyes.Two NIR fluorescent probes WR-Cys and WR-ClO,which can be used to detect Cys and HClO,respectively,was synthesized by a specific synthesis route.The probes exhibited highly selective and sensitive turn-on fluorescence responses for Cys and HClO respectively.In addition,the probes were successfully used for visualizing endogenous Cys and HClO fluctuations in living cells.We anticipate that WR-Cys and WR-ClO will be promising chemical tools to understand the roles of Cys and HClO in the regulation of cellular redox state.