Synthesis Methodology Of Cyanine Fluorescent Probes And Application In Detection Of Nitroreductase

At present,fluorescence imaging technology has great potential in the field of medicine in the fields of tumor detection,bacterial diagnosis,gene expression,drug receptor analysis,drug screening and therapeutic evaluation.As one of the cores of fluorescence imaging technology support,fluorescent probes,the development of new and efficient fluorescent probes can better identify and diagnose diseases,and provide new technologies and ideas for the development of new drugs.At present,fluorescent probes based on cyanine dyes have become a research hotspot because cyanine dyes have the advantages of high extinction coefficient,long absorption and emission,and high quantum yield for biological detection.Among the cyanine dyes,especially the derivative of the fluorescent sensor Cyanine 5(Cy5),the absorption and emission peaks in the near-infrared region are suitable for in vitro and in vivo experiments.At present,the introduction of functional groups on its polyene backbone mainly depends on the construction of the key intermediate-halogenated Cy5,but the current synthetic method has a complicated route,harsh reaction conditions,many by-products,low yield,and serious Limits the application of Cy5 dye functionalization.This paper has discovered a rapid and convenient synthesis of a new method for the synthesis of Cy5 fluorescent probes for ruthenium-halide(Br-,I-)or pseudo-halides(SCN-,SeCN-),we first make an anion exchange of Cy5(X-)with the corresponding halogen ion or pseudo-halide ion through a simple ion exchange reaction,and then the anion oxidation reduction potential is different,X-can be N-chlorinated Succinimide(NCS)is oxidized to form an X-Cl intermediate which can be rapidly electrophilically substituted with Cy5 dye to form a hydrazine-halogenated or pseudohalogenated Cy5 fluorescent probe.Through this simple synthesis method,we can obtain a variety of halogenated or pseudohalogenated products,expand the diversity of such halogenated intermediates,and simplify the synthesis of such compounds.The method has mild reaction conditions,single product and high yield,and provides a new and efficient synthesis route for the synthesis of Cy5 fluorescent probes.Nitroreductase(NTR)has a good application prospect in the fields of drug activation,tumor therapy,and inhibitor research and development.It is important to further understand the biological function and measure the state of the organism by measuring the nitroreductase in the biological system.In recent years,fluorescent molecular probes for detecting nitroreductase have been continuously researched and developed for the detection of nitroreductase in bacteria and cells.However,there are few studies on activated fluorescent molecular probes.Therefore,a series of nitroreductase-activated fluorescent molecular probes were designed based on the bromo Cy5 dye for the first time.Test for the diagnosis of bacterial infections.Based on the bromo Cy5 dye,we synthesized four novel intelligent fluorescent probes capable of selective detection of nitro reductase by Suzuki-Miyaura reaction.We selected the probe 4 with the best fluorescence activation to detect the fluorescence properties.The results showed that the fluorescence of Cy5 could be quenched by the nitro group;after the action of nitroreductase,the fluorescence recovered and the fluorescence enhancement was 5 times;The detection of various substances confirmed the specific recognition reaction of probe 4 with nitroreductase;it was low in bacteria and cytotoxicity;and the imaging effect in E.coli and S.aureus was remarkable.Explains the versatility and simplicity of the new method.