| Hydrogen sulfide(H2S)is a volatile toxic environmental pollutant with special odor.Now,it is also considered as the third important gas signal molecule,which can regulate cardiovascular,nervous,immune,endocrine and gastrointestinal system.In mammalian systems,endogenous H2S is mainly produced by three specific enzymes catalyzed by cysteine or cysteine derivatives,including cysteine β-synthase(CBS),cysteine y-lyase(CSE),and 3-mercaptopyruvate sulfotransferase(3-MST)in mitochondria or cytoplasm.Obviously,hydrogen sulfide is also involved in a variety of physiological responses to maintain cell health,including vasodilation,angiogenesis,oxygen sensing,cell apoptosis,inflammation and nerve regulation,and it also prevents ischemia/reperfusion injury.On the other hand,unregulated and abnormally concentrated hydrogen sulfide may lead to serious diseases such as Alzheimer’s disease,Down’s syndrome,diabetes and cirrhosis of the liver.Moreover,in some animal models of human beings,H2S has preliminarily shown therapeutic potential.For example,in the experimental model of Alzheimer’s disease,H2S can prevent neuron damage,alleviate cognitive impairment and slow down the progress of the disease.Nevertheless,the clear mechanism of its behavior and the regulation mechanism of its production and destruction are still unclear,partly because it is difficult to monitor its concentration in vivo.Therefore,an ideal method for detecting endogenous hydrogen sulfide in vivo is of great significance and practical value for further elucidating the physiological and pathological role of hydrogen sulfide.Up to now,a large number of sulfide detection methods have been reported,including colorimetry,electrochemical analysis and gas chromatography,among which fluorescent probe detection method is the first choice because of its low invasion and good compatibility.However,it is still challenging to specifically detect H2S in the presence of high concentrations of thiols.This paper developed two specificities of 2-1,3-1,4-1 based on the nucleophilicity and reducibility of H2S.The fluorescent probe of H2S was detected,and the recognition responses of three probes and H2S were studied by fluorescence and ultraviolet spectroscopy and fluorescence imaging.Specific research works are as follows:1.An enhanced fluorescent probe 2-1 based on H2S double nucleophilic properties was designed and synthesized.First,H2S and 2-1 carry a nucleophilic substitution reaction with an electrophilic disulfide bond,and then form an intermediate 2-2 with a thiol group,the sulfhydryl group spontaneously undergoes nucleophilic addition to the adjacent ester group,and the ring The reaction releases coumarin 2-3 and the by-product benzodioxanone 2-4.The probe has a fast response to H2S,high sensitivity and good selectivity.Cellular experiments indicate that probe 2-1 can be used to detect exogenous H2S in A549 cells2.A viscosity-sensitive BODIPY fluorescent probe 3-1 was designed and synthesized,and H2S can be specifically detected.Spectroscopic experiments show that 3-1 can respond quickly to H2S in DMSO.In addition,3-1 showed weak fluorescence in non-viscous media.We studied the fluorescence emission and fluorescence lifetime of 3-1 in different ratios of methanol/glycerol system,and observed fluorescence intensity and decay time with medium viscosity.The increase is enhanced,indicating that 3-1 is a molecule that can be rotated.Biological experiments show that the probe can penetrate the cell membrane,has low cytotoxicity and good selectivity,and can be used to detect the H2S and viscosity in HepG-2.3.A fluorescent probe 4-1 based on FRET mechanism consisting of 7-amino-4-methylcoumarin(energy donor)and fluorescein(energy receptor)was designed and synthesized.The detection limit of this probe is 0.031//M,with high sensitivity and good selectivity,excellent response such as fast response(8 s)and low cytotoxicity.In addition,both HepG-2 cell imaging and mouse in vivo imaging experiments have shown that 4-1 can be applied to detect H2S in biological systems. |
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