The Studies On Synthesis And Performance Of Cyanine-based Near Infrared Fluorescent Probes

With the rapid development of modern science and technology,fluorescence imaging as a kind of intuitive has become a general tool for sensing and optical imaging analysis in situ visualization observation technology.Among them,near-infrared fluorescent probe technology has shown its value in many fields,and has shown a good application prospect in disease detection with advantages of low background interference,little cell damage,strong sample penetration,high detection sensitivity.In various types of near-infrared probes,cyanine dyes have attracted much attention because of their high molar extinction coefficient,high fluorescence quantum yield and high photostability.In this paper,we designed and synthesized a novel fluorescent probe based on cyanine dyes and systematically studied its performance.Firstly,we synthesized a p H fluorescent probe IR780-QLH based on the photo-induced electron transfer（PET）mechanism using benzylpiperazine as the H⁺acceptor group and cyanine dye as the fluorophore.The structure was confirmed by nuclear magnetism(¹H NMR,¹³C NMR),mass spectrometry etc.,and its performance was studied by ultraviolet and fluorescence spectroscopy.The spectral properties studies show that probe IR780-QLH has strong fluorescence under acidic conditions.As the p H increases,the fluorescence intensity gradually decreases and exhibits a linear relationship with p H in the range of p H 3.0-5.0,which was suitable for the detection of strong acids in cells.Furthermore,the probe IR780-QLH has good sensitivity,stability and excellent membrane permeability,so it can be used for the p H detection of in living cells.Secondly,we designed and synthesized a new near-infrared fluorescent probe IR780-QLT with piperazine as the linking arm and phenylborate as the recognition group.Both UV and fluorescence spectra show that probe IR780-QLT has high sensitivity and specificity for ONOO^-,and the color of the probe solution changes significantly（from blue to transparent）.Therefore,the probe can identify ONOO^-with the naked eye.Moreover,cell imaging technology demonstrated that the probe IR780-QLT has been successfully applied to detect exogenous ONOO^-inliving cells.In addition,we found that the probe IR780-QLT has a certain response to mercury ions in PBS（p H=4）.With the addition of mercury ions,the fluorescence of the probe gradually decreases,and finally the quenching effect is achieved.At the same time,the probe IR780-QLT has high selectivity and stability to mercury ions,and can identify mercury ions with the naked eye,which has certain research value.