Design, Synthesis And Performance Study Of A Novel Near-infrared Reactive Biothiol Fluorescent Probe

Thiol-containing biological molecules,such as cysteine(Cys),homocysteine(Hcy)and glutathione(GSH)are vital intracellular thiols in living organisms and have attracted much attention lately for their critical roles in maintaining biological systems.They participated in the process of reversible redox reactions,signal transduction,apoptosis and cell proliferation to regulate the metabolism and cellular homeostasis.Therefore,the levels of intracellular biothiols are directly linked to many diseases including cancers.For example,as an indispensable amino acid,abnormal concentrations of Cys is considered to result in slowed growth rate,hair depigmentation,edema,lethargy,liver damage,skin lesions and so on.Hence,to develop efficient methods for detection and quantification of bio thiols for academic research and the diagnosis of the related diseases has become an important issue.To overcome the disadvantages of current fluorescent probes,four novel raction-based probes have been developed in the thesis.The main contents are as follows:1.An efficient naphthalene-based two-photon fluorescent probe6-(benzo[d]thiazol-2-yl)naphthalen-2-yl acrylate(BTNA)for cysteine(Cys)has been rationally designed and synth-esized in this work,which consists of a 6-(2-benzothiazolyl)-2-naphthalenol(BNO)fluoro-phore connected with an acrylate group(the fluorescence quenching and response group).This probe was designed based on excited-state intramolecular proton transfer(ESIPT)and employed conjugated addition/cyclization sequence mechanism for Cys detection.Importan-tly,this probe shows rapid fluorescent turn-on signal changes for Cys with high selectivity and sensitivity over other amino acids and metal ions including the similar structured homocysteine(Hey)and glutathione(GSH).Finally,the probe BTNA was successfully applied to bioimage intracellular Cys in living cells with low cytotoxicity.2.With traditional fluorescent naphthalene imide group as the precursor,we devised a novel fluorescent probe acrylic acid 4-[6-(4-methyl-piperazin-1-yl)-1,3-dioxo-1H,3H-benzo[de]isoquinolin-2-yl]-phenyl ester(MBPA),the probe use 1,8-naphthalene imide as fluorophore and acrylate groups as recognition.Different from the commom naphthalene imide,we added methylpiperazine to this probe,which is an attempt to improve the probe fluore-scence efficiency and sensitivity.Acrylate groups is commonly used to identify the group.It is based on the dynamic factors of differences and we can design the high selectivity of cysteine fluorescent probe.3.A novel red-emitting fluorescent probe(E)-6-(2-(3-(dicyanomethylene)-5,5-dimethylcyclohex-1-en-1-yl)vinyl)naphthalen-2-yl acrylate(DDNA)for cysteine has been rationally de-signed and synthesized.This novel fluorophore(HDM),which features a large π-conjugatio-n system and typical intramolecular charge transfer(ICT)process,has a long emission w-avelength at 631 nm.Besides that,as a turn-on fluorescent probe which shows high select-ivity and sensitivity for Cys over other metal ions and amino acids including the similar structured homocysteine(Hcy)and glutathione(GSH).Finally,the probe DDNA was succe-ssfully applied to bioimage intracellular Cys in Hela cells with low cytotoxicity.4.A novel turn-on fluorescent probe(E)-6-(2-(3-(dicyanomethylene)-5,5-dimethylcyclo-hex-1-en-1-yl)vinyl)naphthalen-2-yl 2,4-dinitrobenzenesulfonate(DDND)for highly selective detection of bio thiols over other amino acids was synthesized and investigated in the work,which used 2,4-dinitrobenzenesulfonyl(DNBS)group as a fluorescent quencher.The nov-el fluorophore(HDM)features a large π-conjugation system and typical intramolecular ch-arge transfer(ICT)process and has a long emission wavelength at 623 nm as well as a large stokes shift(kem-λex=131 nm).Upon the titration of thiols,the color of the solution can change from yellow to dark red,which means it can be detected by naked eyes.Finally,probe DDND was successfully applied to bioimage intracellular Cys in Hela cells with low cytotoxicity...