Design And Synthesis Of Some Novel Fluorescent Probes And Their Applications For Cell Imaging

Two novel BODIPY fluorescent dyes were designed and synthesized, on the basis of previous experiments. A novel p H probe and a ratiometric fluorescent probe for Cl O- with coumarin fluorophore were designed and synthesized based on ICT mechanism. This paper is divided into four chapters, including the following:The first chapter is a literature review section, which demonstrates the generation of fluorescence, the sensing mechanism of small-molecule fluorescent probes, some typical fluorescent p H probes and hypochlorite probes.The second chapter is concerning the design and synthesis of new BODIPY dyes and their applications for bio-imaging in living cells. The meso-COOEt substituted BODIPYs was designed and synthesized, which exhibited high quantum yield and red to far-red emission. Notably, the meso-COOEt substituted BODIPYs displayed almost separated UV-Vis absorption and emission spectra with a large Stokes shift(~ 60 nm). Time-dependent density functional theory calculations were conducted to understand the structure–optical properties relationship, and it revealed that the large Stokes shift was resulted from the geometric change from the ground state to the first excited singlet state. Furthermore, BODIPY was tested for its ability to image in living cells. The results indicated that Dye-1 was a water-soluble and membrane-permeable probe.The third chapter is concerning the design and synthesis of new p H fluorescent probe and its application for cell imaging. We have developed a highly sensitive and selective p H probe that responds to basic p H with colorimetric and fluorescence turn-on signal. Interestingly, the probe Na OCy displays extremely large Stokes shift(~122 nm), which can effectively avoid auto-fluorescence from cellular species. According to UV-vis spectra and fluorescence titration, a good linearity was obtained and the p Ka is 8.32. In addition, good photostability, fine reversibility and water solubility in 100% PBS solution make it favorable for intracellular p H imaging. The confocal fluorescent microscopic images of subcellular distribution indicates that Na OCy has good cell membrane permeability and could selectively stain nucleus, which is the first example of p H probe with such feature.The fourth chapter is concerning the design and synthesis of new fluorescent probe for hypochlorite and its application for cell imaging. we have designed a water-soluble red-emitting probe based on coumarin–hemicyanine, which displayed a noticeable colorimetric and fluorometric dual response to Cl O- on the basis of a simple alkene cleavage reaction. CMCY exhibited fast response to Cl O- in physiological condition with high sensitivity and selectivity, and extremely low detection limit(0.08 μM). By plotting the ratio of emission intensity(I480/I631) versus the concentration of Cl O-, a good linear relationship(R2 = 0.9932) was obtained with the Cl O- concentration ranging from 0 to 73 μM. Cell staining results indicated CMCY was cell membrane permeable and could be used for visualizing hypochlorite in living cells.The fifth chapter is the conclusion part of the thesis, summarizes the main contents of the paper and some results achieved.