Synthesis And Application Of Near-infrared Fluorescent Probes For Detection Of Hydrogen Sulfide And Sulfhydryl Compounds

The fluorescence probe method has the advantages of simple operation,rapid analysis,high sensitivity,non-destructive,real-time and in-situ detection,and has become a research hotspot in the fields of biology and environment analysis.Hydrogen sulfide and biothiols are important biomolecules and play an important role in physiological and pathological regulation.Thiophenol is an important intermediate used in medicine,pesticides and synthetic fields.Simultaneously,it is a kind of environmental pollutants which is toxic to organisms.Therefore,the design and development of hydrogen sulfide,biothiols and thiophenol probes has very important significance in biological and environmental safety.The research content of this article mainly includes the following four aspects:(1)A near-infrared fluorescent probe(P1)for rapid detection of thiophenol was designed and synthesized.The probe was synthesized by linking aminoporphyrin and 2,4-dinitrobenzenesulfonyl(DNBS).The DNBS group has a dual function of quenching the fluorescence of the porphyrin by the PET process and serving as a response site for thiophenol specific recognition.Thiophenol is a strong nucleophile which can undergoes aromatic nucleophilic substitution(SNAr)reaction with the probe.The PET process is blocked after the sulfonyl group broken.And then the fluorescence is restored after the fluorophore released.The probe has near-infrared emission,large Stokes shift(~227 nm),fast response speed(<20 s),low detection limit(~8.3 n M)and good cell membrane permeability.The probe was successfully used for detection of thiophenol in Hela cells and water sample.(2)A fluorescent probe(P2)with dual wavelength response was designed and synthesized.The probe was synthesized by linking hydroxy Nile Red(NR-OH)and 7-nitrobenzofurazan(NBD)via an ether linkage.Due to the PET effect from hydroxy Nile Red to 7-nitrobenzofurazan,the probe itself does not have fluorescence,and the ether bond at the junction is the response site of Cys?Hcy and GSH.When the probe reacts with GSH,the red fluorescence at ?em=635 nm of NR-OH will be emited,while the other product NBD-GSH has no fluorescence due to the quenching effect of sulfur atom,and only the red fluorescence will be observed(single fluorescence emission peak).After the probe reacts with Cys and Hcy,it will emit red fluorescence at ?em=635 nm of the NR-OH.Moreover,due to the special rearrangement reaction of the other product NBD-Cys ? NBD-Hcy,amine substituted derivatives will be formed with a strong green fluorescence.So the red fluorescence and green fluorescence can be clearly observed(double fluorescence emission peak).Therefore,effective discrimination and detection of GSH and Cys/Hcy can be achieved based on different fluorescence emission characteristics.(3)A porphyrin fluorescent parent with dual active functional groups(hydroxy and amino)was designed and synthesized by functional group modification.With tetraphenylporphyrin as the starting material,two nitro groups were introduced on the benzene ring around the porphyrin by nitration,and then part of the reduction was used to reduce one of the nitro groups to an amino group.Amino group was converted to hydroxyl group by diazotization and hydrolysis reactions.Finally,another nitro group was reduced to an amino group.The fluorescent parent(5-(4-aminophenyl)-10-(4-hydroxyphenyl)-15,20-diphenylporphyrin)which have two reactive groups(hydroxyl and amino)was obtained.The fluorescent parent has greater absorption and emission wavelengths than tetraphenylporphyrin,and the emission wavelength is in the near infrared band.The fluorescent parent can be further functionalized and modified by active functional groups,and has potential application value in preparing multifunctional fluorescent probes.(4)The self-synthesized porphyrin which contain two reactive functional groups was used as fluorophore.The fluorophore was attached to 2,4-dinitrophenylsulfonyl via a hydroxyl group,and attached to a methoxy polyethylene glycol amino group via an amino group and a bridging group.Then a hydrogen sulfide fluorescent probe(P3)with dual function of near infrared emission and water solubility was synthesized.The 2,4-dinitrobenzenesulfonyl moiety of the probe acts as a specific recognition site for hydrogen sulfide,the porphyrin acts as a near-infrared fluorescence emission group,and the methoxy polyethylene glycol amino provides a good function of water-soluble and fat-soluble.The probe can achieve rapid,highly sensitive and highly selective detection of hydrogen sulfide in the whole aqueous solution.The detection limit is as low as 12.7 n M,and it has been successfully applied to the detection of hydrogen sulfide in human urine and serum.