Design,Synthesis And Properties Of A Small Molecule Fluorescence Probe For Simultaneous Detection Of Glutataione And Cysteine

Bio-thiols play an important role in the physiological processes of the human body.Once the concentration of abnormal,it will bring some disease.Therefore,qualitative and quantitative detection of biological thiols(including:Cys,Hcy,GSH),for people is very necessary.Fluorescent probes have been recognized as the most efficient molecular tools that can help visualize trace amounts of targeted biomolecules in biological systems due to their simplicity,sensitivity,real-time imaging,and nondestructive detection.In addition,we summarize research on previous work by finding,previously reported articles on the detection of biothiols,mostly single detecting a biothiols.Therefore,the development of a small molecule fluorescent probe to achieve from different emission wavelengths to detect two or three biothiols is of great value and challenging.Considering the above problems,we have designed and synthesized a novel fluorescent probe 1,and have been structurally related to its structure(NMR,carbon spectrum,and mass spectrometry)to finalize the structure of the compound.In the structural design of probe 1,we used hemi-cyanide dyes containing coumarin-indole as a fluorophore,and 3,4-dimethoxy-thiophenol was used as a photoinduced electron transfer(PET)to ensure a low background fluorescence of the fluorescent quencher and the leaving group.Probe 1 can selectively detect GSH and Cys at different emission wavelengths at the same time,and it can be distinguished from other amino acids and essential cations.In the long wavelength(651 nm),pure water system,the probe 1 reacts with GSH,only one step aromatic substitution(SNAr)reaction,the formation of thio-coumarin hemocyanine dye(1-GSH),showed enhanced fluorescence.Probe 1 reacts very fast with GSH with a fluorescence response time of 10 s.The sensitivity of the probe 1 to the change in fluorescence intensity due to the change in GSH concentration was extremely sensitive,with a minimum detection limit of 8.8 nM.The probe 1 reacts with Cys,the first step of the aromatic substitution reaction,the formation of thiol-coumarin-hemocyanine dye(2a),followed by intramolecular rearrangement reaction,the formation of amino-coumarin-hemocyanine dye(3a),and then occurred The cyclization reaction within the molecule produces compound 4a,which makes it significantly enhanced at 457 nm.Compared to Cys,the probe 1 reacts with the Hcy to undergo a cyclization reaction to form an eight-membered ring,which is notoriously kinetic and the steric hindrance of two methyl groups linked by indole nitrogen.Eventually leading to the reaction of the probe 1 with Hcy to produce most of the compound that remained in the intramolecular rearrangement reaction of the product 3b.So probe 1 can be used to selectively detect Cys different from Hcy/GSH and other analytes.In particular,the probe 1 for the Cys competitive experiments,fully embodies the probe 1 for Cys detection has a strong anti-interference ability.Finally,the probe 1 was performed on a cell imaging experiment to identify the biothiol in cells.It is shown that the probe 1 can selectively recognize GSH and Cys in living cells under different organic solvent concentration and emission channel,and has certain potential biological application value.