Design, Synthesis And Performance Study Of Several Novel Biological Thiol-reactive Fluorescent Probes

Functional fluorescent dyes play an important role in lots of fields,such as chemical sciences,environmental sciences,life sciences and medicine.It has become a hot research spots in recent years.Typically,small-molecule fluorescent probes possess several advantages,such as easy to design and synthesize,low cost of synthesis,high structural controllability,the recognition of irreversible chemical reaction,real-time cell imaging for living cells.Therefore,the fluorescent probes has been attached great importance by domestic and foreign scientific research workers.However,the practical biological applications of the probes will usually be subject to some limitations,such as selectivity,sensitivity,response time and so on.Different from the traditional fluorescent probes,the reaction-based fluorescent probes utilize its own reaction site and the irreversible chemical reaction for the analyte so as to express information.These probes minimize damage and interference to the living systems.Hence,it is an important area of research to develop novel reaction-based fluorescent probes for detecting various chemically and biologically relevant substances with rapid,highly selective and sensitive property.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.Using 1,8-naphthalimide as the fluorescent chromophore,and by modifying the structure of the parent structure,based on the Michael reaction of-SH of biothiol and α,β-unsaturated double bond,and then intramolecular cyclization reaction,a novel reaction-based fluorescent probe 2-(4-acryloyl oxy-phenyl)-1,3-dioxo-2,3-dihyd ro-1H-benzo[de]isoquinolin-6-yl acrylate(ABPA)with dual reaction sites for detecting Cys with high selective,sensitive and short response time was developed,it can serve as a "naked-eye" indicator for Cys.Additionally,Hey,GSH almost none interference for Cys detection.This novel probe ABPA was used for assy and imaging of Cys in living Hela cells.2.A novel benzothiazole-based biothiols fluorescent probe 2-benzothiazol-2-yl-5-(2-chloro-acetoxy)phenyl chloroacetate(BPBC)was designed and synthesised,which possess dual reaction sites.The reaction of probe BPBC with thiols proceeds through a nucleophilic substitution and cyclization sequence was given out.The research results indicate that probe BPBC has a good recognition of Cys and Hey over other analytes.This probe has the better selective and sensitive for Cys than Hcy.With the increase of cysteine concentration,the fluorescence intensity of the detection system also increased.Furthermore,this probe was successfully applied to bioimage Cys in living cells with low cytotoxicity.3.A novel reaction-based turn on near-infrared probe 4-(1E)-[2-(3-dicyanomethy lene-5,5-dimethyl-cyclohex-l-enyl)-vinyl]phenyl acrylate(DP-NIR)based on pyranonitrile has been successfully synthesized.Acrylate bond is selected for the response units of Cys.The research results indicate that the high selectivity of probe was ascribed to the blockage of the ICT process caused by the Michael addition reaction of-SH with α,β-unsaturated double bonds.Thereby,remarkable red shift of absorption was obtained.In the process of identification of probe DP-NIR with cysteine,the solution of system changed from light yellow to brown,while other analytes do not have this phenomenon.Thus,it is feasible for Cys detection in the naked-eye model.In addition,this probe has high sensitivity and selectivity for Cys detecting.The results of cell imaging displayed that probe DP-NIR can be used for detecting Cys in living cells.4.Using 3-hydroxyflavone as the matrix,not only by incorporating cinnamaldehyde to increase the conjugated system of the molecular structure,but also by incorporating acryloyl chloride moiety as the specific recognition group,synthesized a novel reaction-based turn on red-emitting fluorescent probe 4-oxo-2-(1E)-styryl-4H-chromen-3-yl acrylate(SCA).The experimental results show that the emission wavelength of probe SCA longer than 600 nm,have good photostability and large Stokes shift.This probe displayed remarkable fluorescence enhancement toward Cys with high selectivity.Moreover,probe SCA has been successfully used for Cys imaging in living cells.