Design,Synthesis And Application Of Fluorescent Probes For Reactive Sulfur And Reactive Oxygen

Reactive oxygen species?ROS?and Reactive sulfur species?RSS?play an important role in vivo,and their fluctuation of physiological level is closely related to some physiological diseases.Therefore,the detection of ROS and RSS is of great significance in the related biological and medical fields.Traditional detection methods such as high-performance liquid method,atomic spectroscopy,mass spectrometry have the disadvantages of time-consuming,cumbersome detection methods,and low sensitivity.However,fluorescent probes have attracted extensive interest and become an indispensable detection tool in modern scientific research and disease diagnosis because of its advantages,such as simple operation,high sensitivity,real-time cell imaging,low toxicity,high selectivity and high efficiency.Developing fluorescent probes that can detect two or more kinds of ROS and RSS simultaneously is the current research frontier and also a challenge.Aiming at the above-mentioned problems,this paper designed fluorescent probes that simultaneously distinguish multiple ROS and RSS.The specific work is as follows:?1?Based on coumarin as the dye precursor,a 7-nitro-1,2,3-benzoxadiazole?NBD?and azide?-N₃?groups were used as recognition sites,and a new type of fluorescent probe was designed and synthesized.COU-N₃-NBD is used to distinguish between cysteine?Cys?/homocysteine?Hcy?and hydrogen sulfide?H₂S?.Due to the strong photoinduced electron transfer?PET?interaction between the recognition group and coumarin parent,the probe itself does not emit fluorescence.Adding Cys/Hcy can induce the departure of the NBD group,and at the same time generate the corresponding mercapto NBD substitute NBD-S-Cys/NBD-S-Hcy.NBD-S-Cys/NBD-S-Hcy is unstable,and further intramolecular rearrangement will occur,generating the corresponding amino NBD substitute NBD-N-Cys/NBD-N-Hcy,thus emitting strong green fluorescence.When H₂S is added,it can not only induce the departure of the NBD group,but also reduce the N₃ group on the coumarin structure to an amino group,generate amino coumarin,and emit blue fluorescence.The probe has the advantages of high selectivity,etc.,and its detection limit is as low as 1.12?M.?2?By integrating a phenothiazine moiety as an electron donor and an acetyl moiety as the electron acceptor,a novel D-?-A system dye,PTZAc,with a broadband emission spectrum?the full width at half maxima can reach to 123 nm?and a large Stokes shift?up to 217 nm?was synthesis.Based on this platform,a novel 2,4-dinitrophenyl-ether type fluorescent probe,PTZAc-1,for thiophenol detection was designed and synthesized.2,4-dinitrophenyl ether can effectively initiate PET process and quench the fluorescence of the probe itself.Adding thiophenol,due to the strong nucleophilicity of thiophenol,could trigger the cleavage of 2,4-dinitrophenyl-ether moiety,releasing the dye PTZAc,thereby giving a strong fluorescence signal.The probe has the advantages of high selectivity,high sensitivity?detection limit as low as 1.03?M?,and wide open fluorescence emission spectrum.This probe successfully demonstrated the multi-channel application of PTZAc-1 in intracellular thiophenol imaging in live RAW 264.7 cells.?3?Based on n-butyl substituted phenothiazine as the parent,4-?trifluoromethylsulfonyl?phenyl ether as O₂·^-recognition group,4-bromomethylphenylboronic acid pinacol is H₂O₂ and the heterosulfur atom on the phenothiazine structure is a specific recognition group for HCl O,construct fluorescent probes PTZ-CN,PTZ-COOEt that can sequentially detect O₂·^-and HCl O,and probe PTZ-BO-CN that sequentially detect H₂O₂ and HCl O.The structure of the probe molecule was determined by nuclear magnetic resonance hydrogen-carbon spectroscopy.Unfortunately,when we analyze the three probes in response to the detection substances by ultraviolet and fluorescence,the response of the probes to the sequential detection of two reactive oxygen species in the commonly used test system is not good.Moreover,it failed to be consistent with the detection mechanism envisioned by the design,and the probe was not well applied.