Design,Synthesis And Biological Imaging Study Of Organic Small Molecule Reaction-based Fluorescent Probes

Fluorescent probe is widely used because of their simplicity,great temporal and spatial sampling capacity.Excellent fluorescent probes are the basis for the development of novel optical sensing systems.Recently,organic small molecule reaction-based fluorescent probes have attracted much attention in analytical and biological fields because of their excellent selectivity and sensitivity.Here,we have designed and synthesized three reactive fluorescent probes to detect Fe³⁺,F^-,glutathione?GSH?and H₂O₂.The mainly results were briefly summarized as following:?1?A new fluorescent probe R6GES based on Rhodamine 6G was designed and synthesized for the detection of Fe³⁺.The Fe³⁺irreversibly bind to the R6GES and induce the ring opening and hydrolyzing of spirolactam in the Rhodamine unit.The probe R6GES can be used for the detection of Fe³⁺without interference from other competitive metal ions.The tested concentration range and the limit of detection?LOD?of the probe were 0³0.00?mol/L and 0.030?mol/L,respectively.The present probe was applied to the determination of Fe³⁺in drinking water samples.The average recoveries ranged from 102.40%to 104.55%at spiked concentration level of20.00?mol/L.Furthermore,the fluorescent probe also can be applied as a bioimaging reagent for Fe³⁺detection in BEL-7402 cells.?2?A novel fluorescent probe?Flu-Si?based on fluorescein and coumarin fluorophores for highly selective and sensitive detection of F^-was successfully developed.It was shown that the mechanism of recognition involves a desilylation reaction that takes place after addition of F^-anions.A linear relationship between the ratio of emission intensities at 532 and 465 nm(I₅₃₂/I₄₆₅)and F^-concentration over the range of 0-20?mol L^-1 with a LOD of 0.025?mol L^-1 was found.The sensing mechanism of Flu-Si with F^-was confirmed by density functional theory?DFT?and time dependent density functional theory?TDDFT?calculation.Moreover,it was demonstrated that Flu-Si is an efficient fluorescent probe for F^-anions in living cells and zebrafish,indicating its sensing potential in clinical diagnosis.?3?A water-soluble,near-infrared fluorescent probe?EQR-S?was designed for the measurement of the GSH concentration.Responses of different interfering substances to the developed probe were investigated,and the luminescence mechanism was examined by theoretical calculations.Results revealed that EQR-S can be applied for the rapid,sensitive determination of the GSH concentration with a detection limit of 69 nM.Based on the above advantages,EQR-S was successfully applied to investigate the fluctuation in the GSH concentration of living cells under high-temperature stress.?4?A novel fluorescent probe?NRBE?for detecting H₂O₂ was developed using benzyl boronic ester as the H₂O₂-recognized group and Nile red as the matrix.The probe has several advantages,such as good selectivity,high sensitivity?LOD=75nM?,good water solubility and emission in the near-infrared region?ex/em:585/670nm?.With the NRBE probe,the endogenous H₂O₂ in human hepatocellular carcinoma cells BEL-7402,was detected,and the H₂O₂ generated during the ischemia-reperfusion of the cells was imaged.These results show that NRBE can be applied for real-time detection of H₂O₂ in biological systems.