Synthesis And Application Of Fluorescent Probes For Several Bioactive Substances

Small-molecular fluorescent probes have been widely used in various fields due to the unique properties of controllable structure,specific,low toxicity and visual detection,such as biology,medical science,pharmacology and environmental science.At present,various fluorescent probes have been reported for the detection of certain substances in biology or environment.However,in complicated biological systems,measurement based on a single emission wavelength fluorescence intensity signal was susceptible to the concentration of probe,inherent fluorescence,instruments and environmental factors,resulting in inaccurate quantitative analysis.The inevitable self-absorption and autofluorescence of biological systems made short-wavelength emission fluorescent probes unsuitable for deep imaging in tissues and living bodies,limiting their further applications in biological systems.Therefore,in this paper,by designing ratiometric or near-infrared?640-900 nm?fluorescent probes,the background interferences,such as autofluorescence and self-absorption were minimized to achieve the detection of active substances in complex biological samples,such as,alkaline phosphatase?ALP?,hydrogen peroxide?H₂O₂?and cysteine?Cys?.Three kinds of fluorescent probes were designed and synthesized,and the specific contents as follow:?1?Based on the specificity of ALP to catalyze the hydrolysis of phosphate groups on various substrates,a ratiometric fluorescent probe 2,4-bis?benzo[d]thiazol-2-yl?phenyl dihydrogen phosphate?PDP?with visible light emission was designed and synthesized for the detection of ALP.In the presence of ALP,the phosphate group in the PDP reacted with the ALP enzymatically,releasing hydroxyl groups,and the fluorescence emission was red-shifted to achieve ratiometric fluorescence detection of ALP.With the linear range of 0.2-65 U/L,the detection limit of ALP was 9.94×10^-2 U/L based on signal-to-noise ratio S/N=3,which was lower than most of probes reported.The probe had high selectivity and sensitivity for ALP,and had been successfully applied to the detection of ALP in human serum samples.?2?Based on the nucleophilic substitution reaction between H₂O₂and borate group,a colorimetric and fluorescent dual-signal probe2-??6-??4-?4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl?benzyl?oxy?-2,3-di hydro-1H-xanthen-4-yl?methylene?malononitrile?DRP-B?was designed and synthesized for the detection of H₂O₂.The intermolecular charge transfer?ICT?effect of DRP-B was disturbed by the electron-withdrawing of the borate group and malononitrile group,leading to fluorescence quench.In the presence of H₂O₂,DRP-B happen cascade reaction to release hydroxyl groups,and the fluorescence enhanced due to the recovery of ICT effect.At the same time,the color of the solution changes from pink to blue,enabling colorimetric and near-infrared fluorescence dual-signal detection of H₂O₂.With the linear range of 0.2-42?M,the detection limit was 1.20×10^-1?M based on the signal-to-noise ratio S/N=3.In addition,DRP-B had been successfully applied to imaging of H₂O₂ in HeLa cells and zebrafish due to its advantages of high sensitivity,selectivity and NIR optical properties.?3?Based on the addition-cyclization reaction of Cys and acrylate groups,a colorimetric and fluorescent dual-signal probe?E?-2-?2-?6-?acryloyloxy?-2,3-dihydro-1H-xanthen-4-yl?vinyl?-3-methylb-enzo[d]thiazol-3-ium iodide?DXM?was designed and synthesized for the detection of Cys.The ICT effect of DXM was disturbed by the electron-withdrawing of iminium cation and acrylate group,leading to fluorescence quench.In the presence of Cys,the hydroxyle group released after the reaction between DXM and Cys,and the fluorescence enhanced due to the recovery of ICT effect,accompaning with the color of solution changed from purple to blue,which achieved detection of Cys with colorimetric and fluorescence dual-signal.With the linear range of0.2-20?M,the detection limit was 1.02×10^-1?M based on the signal-to-noise ratio S/N=3.Based on the excellent properties of DXM of low toxicity,high selectivity,good cell compatibility and the near-infrared excitation/emission,it had been successfully applied to imaging of endogenous Cys in HepG2 cells and zebrafish.