Design,synthesis And Biological Imaging Study Of Reaction-based Anion Fluorescent Probes

Anions commonly exist in the biological system and play an important role.Therefore,detection of anions is of great significance for the protection of human health and the ecological environment.Fluorescent probes possess many advantages,such as high sensitivity,good selectivity,and fast response.When the probes were used for living biological imaging,there was almost no damage to the cells and exhibits high spatial and temporal resolution at the same time.Here,we designed and synthesized three reactive fluorescent probes to detect CN-,SO32-and ClO-.The mainly results are briefly summarized as following:(1)The Schiff base "turn-on" fluorescent and chromogenic probe BHDB was used for CN-detection under physiological pH.Based on nucleophilic reaction of imine(-CH=N-)and CN-,when fluorescent intensities in the presence and the absence of CN-were F and F0,respectively,the intensity ratio(F/Fo)of 66 to in the presence of 100 ?mo/LCN-,and a remarkable color change from colorless to yellow were observed.The experimentally observed changes in the spectral properties of the probe in the presence of CN-were systematically studied using high resolution electrospray ionization mass spectrometry(HR-ESI-MS),proton nuclear magnetic resonance(1H-NMR),and time-dependent density functional theory(TDDFT)calculations.Using the fluorescence spectra changes,we found a detection limit for CN-of 0.15 ?mol/L,far lower than the maximum permissive level of CN-(1.9?mol/L)in drinking water recommended by World Health Organization(WHO).Moreover,the novel probe demonstrated fluorescence imaging of CN-in living cells and zebrafish,suggesting its potential in clinical diagnostics.(2)We report a new carbazole-benzo[e]indolium(CEBI)dye as a ratiometric fluorescent and chromogenic probe for sulfite(SO32-)detection based on intramolecular charge transfer(ICT)mechanism.The ratio of fluorescent intensity at 465 nm to that at 600 nm(F465/F600)increases with the increase of SO32-conceitration together with a color change from red to weak red and a large shift(135 nm)in emission wavelength.The experimentally observed changes in the spectral features of the probe in the presence of SO32-were systematically studied using HR-ESI-MS,IH-NMR,and TDDFT calculations.We found a linear relationship between the ratio of fluorescence intensities at 465 nm and 600 nm(F465/F600)and SO32-concentration in the range of 0-20 ?mol/L with a detection limit of 0.025 ?mol/L.Moreover,the experiment results demonstrated that the probe can be applied to the fluorescence imaging of SO32-in living cells and zebrafish,suggesting its potential in clinical diagnostics.(3)A novel fluorescent probe(FCZ)based on fluorescein and carbazole fluorophores for highly selective and sensitive detection of hypochlorite(ClO-)was successfully developed.Comprehensive analyses by electrospray ionization mass spectrometry(ESI-MS),thin-layer chromatography(TLC),nuclear magnetic resonance(NMR),and density functional theory/time-dependent density functional theory(DFT/TDDFT)revealed that CIO' could react with the imine bond of the probe,forming fluorescein,resulting in a significant increase of fluorescence emission intensity(530 nm).The probe has a detection limit for CIO-in water of 0.056 ?mol/L,In addition,the probe was successfully applied to the detection of CIO-in real water samples,as well as in the imaging of ClO-in RAW264.7 cells and zebrafish.