Study On H₂S Cleavage Reaction Of NBD-amine And Development Of H₂S Probe With Rapid Reaction

H2S is discovered to be the third gasotransmitter,which plays an important role in numerous physiological and pathological processes,Real-time and in-situ detection of endogenous H2S helps to gain insight iinto its physiological function.Compared with the traditional methods,fluorescence molecular probe as a method of detecting endogenous H2S has the advantages of fast response,in-situ detection,easy implementation and good biocompatibility.Previously,NBD amine has been developed as a hyrdrogen sulfide recognition group,but the reactivity and selectivity of amine cleavage reactions need to be further elucidated.In the second chapter of this article,the cleavage reactions of NBD amine toward H2S were studied systematically.First,a series of NBD-based probes were synthesized from different organic amines,and then the NBD amines cleavage reactions were tested by fluorescence and UV absorption spectroscopy.It was found that the probes based on piperazinyl-NBD and piperidinyl-NBD could react with micromolar H2S under physiological conditions,while other probes only reacted with millimolar H2S.We also found that acetylpiperazinyl-NBD can be used to prepare test strips to visualize H2S.In order to further extend the application of piperazinyl-NBD as hydrogen sulfide recognition group,we combined it with BODIPY,a fluorescent dye with good photostability and high quantum yield,in the third chapter of this article,and designed a novel and fast-response H2S fluorescence probe BODIPY-NBD.It can be used for the highly sensitive detection of H2S,with a detection limit of only 138 nM.Meanwhile,the probe displayed low cytotoxicity and good photostability and can be used for fluorescence imaging of endogenous H2S in living cells.We believe that BODIPY-NBD can be an excellent tool for real-time detection of cellular endogenous H2S.We further found that introducing a positive charge into the probe could accelerate the NBD amine cleavage reaction.In chapter four of this paper,we used fluorescein and rhodamine B as fluorophores to synthesize probes fluorescein-NBD and rhodamine-NBD,respectively.Fluorescein-NBD exhibited 65fold fluorescence response after reaction with H2S.Rhodamine-NBD reacted very fast with micromolar H2S(t1/2=1 min)and can be applied to the real-time detection of hydrogen sulfide.Rhodamine-NBD probe was successfully used to detect mitochondria-targeted hydrogen sulfide and to image hydrogen sulfide in live mice.