Design And Synthesis Of Fluorescence Probes With Selenium And Sulfur Atoms And Their Bioapplications

With the advantages of simple synthesis,multiple identifying groups,cell membrane penetrable,low biological toxicity and so on,small molecular fluorescent probes supplemented by confocal imaging technology have been to be powerful tools for the detection of bio-active molecules and important ions.As the active molecules have short lifespan,high reactivity,fast transient conversion and the relative single fluorophore,probes for them need to meet high requirements including high stability,fast responsive,spectral diversity and so on,which limited the practical application of the probes to some extent.Furthermore,near infrared fluorescent probes to detect analytes at subcellular level are rare.According to the key points mentioned above,the following work is mainly carried out in this thesis:In chapter 2,we synthesized the lysosome-specific probe Lyso-1 for the detection of HOCl by using of a HOCl-promoted specific oxidation of the rhodamine 6G hydrazone moiety which triggered the ring opening of the spirolactame.To achieve this organelle-targetable fluorescent probe,we introduced a morpholine unit onto a hydrazone,thereby,efficiently yielding the probe Lyso-1 which is found to specifically localize in lysosomes of the living L929 cell.This cell-permeable probe can detect HOCl both endogenously and exogenously.Then,we synthesized a mitochondria-targetable probe Mito-1for HOCl by incorporating phenothiazine moiety into the chromenylium-cyanine fluorophore,a type of near infrared?NIR?dyes with cell permeability and low cytotoxicity.After reaction with HOCl,the probe Mito-1 displays an extremely fast?3 s?turn-on fluorescence response at672 nm,possesses NIR emission,large Stokes shift?ca.100 nm?,a prominent turn-on fluorescence signal?50-fold fluorescence enhancement?and high selectivity.Furthermore,the probe Mito-1 can also be used for endogenous HOCl imaging in living cells.Simallarly,we synthesized probe LSe for ONOO^-by incorporating Se atom into the chromenylium-cyanine fluorophore,by using of ONOO^-promoted oxidation of Se to Se=O yielding a typical ratiomatric probe.This cell-permeable probe can detect ONOO^-both endogenously and exogenously,and would be a potencial tool for further uncovering the physiological effect of ONOO^-.In chapter 3,we designed and synthesized new hemicyanine-based probes TzSO,CcSO and SpSO/MpSO by one step condensing of 3-ethyl-2-methyl benzothiazole iodide,chromenylium-cyaninefluorophoreandN-sulfopropyl-4-methylpyridineor1,4-dimethylpyridinium iodide with methyl sulfoxide benzaldehyde respectively.Compared with the probes which have been reported in the literature,the probes maintain a high selectivity for MsrA among other reduction in the cell components,and can be applied to the analysis of MsrA in different cells.And what makes them more outstanding is that probe TzSO displayed much shorter response time to MsrA?<20 min?;while probe CcSO was found to specifically localize in mitochondria with Pearson's coefficients over 0.97.The development of TzSO,CcSO and SpSO/MpSO enriches the toolbox for exploring MsrA in living systems.In chapter 4,we reported a novel ratiometric NIR fluorescent probe L-NS2O2 based on chromenylium-cyanine fluorophore with chelate unit NS₂O₂ for highly sensitive and selective detection of Hg²⁺ions.By esterification of the hydroxyl group with acetic anhydride of previously reported chelate unit NS₂O₂,high selectivity and sensitivity?9.59 nM?were achieved for detection of Hg²⁺ions in aqueous media.By taking advantage of the nature of NIR emission from the chromenylium-cyanine fluorophore,the probe L-NS2O2 exhibited a NIR fluorescence emission at 728 nm and a blue-shifted NIR fluorescence at 663 nm after chelating with Hg²⁺ions and worked as a ratiometric NIR fluorescence probe.In addition,the probe L-NS2O2 exhibited a very fast response to Hg²⁺ions.The excellent performances of the probe L-NS2O2 enable the application of its in living cells for the ratiometric visual monitoring of the Hg²⁺ion by confocal laser scanning fluorescence microscopy.