Construction Of A Novel Hydrogen Sulfide Fluorescent Probe And Its Application

Hydrogen sulfide（H₂S）,accompanied by rotten egg smell,which is known as a smelly gas.Traditionally it has been considered as a toxic environmental pollutant.However,with the development of knowledge,the current understanding of H₂S has changed.H₂S,similar to nitric oxide and carbon monoxide,which is considered as a third endogenous gas transmitter involved in the regulation of physiological activities in the immune,nervous,cardiovascular,and endocrine systems.Endogenous H₂S is mainly produced by Cys or Hcy through enzymatic pathway,in which cysteine-β-synthase（CBS）,cysteine aminotransferase（CAT）,cystein-γ-lyase（CSE）and 3-mercaptopyruvate sulfur transferase（MST）are related to the endogenous production.On the other hand,studies have shown that disorder H₂S in organisms are associated with some common diseases,such as Alzheimer’s disease,Down syndrome,diabetes and cirrhosis of the liver.Therefore,it is necessary to carry out sensitive and effective methods to detect H₂S in biological systems.Compared with other traditional methods for the detection of H₂S,the fluorescent probe has the advantages of simple operation,nondestructive and sensitive.However,some of the reported fluorescent probes still have some problems,such as poor selectivity,low sensitivity and complex synthesis,etc.Therefore,it is of great significance to design a simple,high selectivity and high sensitivity H₂S fluorescent probe.In this paper,based on the research status of H₂S probes we have designed and synthesized three new hydrogen sulfide probes for the detection and imaging of H₂S.In the first case,we selected 7-hydroxy-coumarin as the fluorophore and 2,4-dinitrophenyl as the reaction site to designed and synthesized a novel H₂S fluorescent probe CMHS.The probe CMHS is a fluorescence-enhanced probe synthesized based on PET mechanism.2,4-dinitrophenyl has a strong electron absorption effect,and the probe CMHS shows fluorescence quenching through PET process.When H₂S was added,PET mechanism was inhibited and ICT process was triggered.The probe CMHS showed strong blue fluorescence at455nm.The CMHS probe has a simple synthesis process,a large fluorescence enhancement factor（180 times）,and a high selectivity and sensitivity.The detection limit of H₂S reaches 2.31×10^-7 M.Meanwhile,the data show that the probe has low cytotoxicity,and can be applied to the imaging of exogenous and endogenous H₂S in organisms.In the second case,a new H₂S fluorescent probe CDNS-HS was designed and synthesized by introducing 2,4-dinitrobenzene sulfonyl as the reaction site of H₂S based on coumarin platform.In the probe molecules,2,4-dinitrobenzene sulfonyl group can not only serve as the recognition site,but also quench the fluorescence of the probe by donor-excited light-induced electron transfer（d-PET）process.The CDNS-HS probe can specifically identify H₂S and has high selectivity by fluorescence spectrum analysis.Through imaging experiments,CDNS-HS probe can detect endogenous and exogenous H₂S in He La cells.In the third case,we designed and synthesized a fluorescence quenching probe XG-H₂S based on pyronin dye.The probe is easy to synthesize and can be obtained by only one step reaction.Probe XG-H₂S uses Michael-addition reaction as the mechanism of H₂S detection.Probe XG-H₂S exhibits a strong fluorescence signal at 560 nm.In the presence of H₂S,the probe has obvious fluorescence quenching phenomenon.At the same time,XG-H₂S shows high sensitivity and excellent selectivity.In addition,probe XG-H₂S has the ability to target mitochondria and has been successfully applied to the detection of exogenous and endogenous H₂S in living cells.