Application Of Organic Small Molecule Fluorescence Probes In The Analysis Of Carbon Monoxide And Hydroxyl Radicals

Fluorescence analysis has been widely studied due to its high selectivity,high sensitivity,simple operation,good reproducibility,fast response,non-invasiveness,intuitiveness and real-time monitoring.As one of the tools of fluorescence analysis method,organic small molecule fluorescent probe has the advantages of strong controllability,easy purification,targeted design,strong chemical modification ability,high fluorescence quantum yield and so on.Therefore,organic small molecule fluorescent probe has been widely used in fluorescence analysis.The organic small molecule fluorescent probe usually consists a fluorophore,a linking group and a recognition group.This paper has made a comprehensive review on the research development of the organic small molecule fluorescent probes of common fluorophores,including coumarin,naphthalene,fluorescein,cyanine,BODIPY and so on.On this basis,the appropriate fluorophore and luminescence mechanism were selected to synthesize organic small molecule fluorescent probes which could detect biologically active substances.The main work has the following aspects:（1）Among the organic small molecule fluorescent probes for detecting Carbon monoxide（CO）,the fluorescent probe designed based on the Pd⁰-mediated Tsuji-Trost reaction has the advantages of simple synthesis,fast response time and so on.Thus,we chose the mechanism to detect CO in biological systems.We designed and synthesized the organic small molecule fluorescent probe Np-CO,which used ester group to link allyl group（recognition group）and 1,3-benzothiazol-2-yl-naphthalene（fluorophore）.Np-CO is a ratiometric fluorescent probe,which could increases the accuracy of the experimental results.It took only 13 minutes for Np-CO to completely react with CO,and the value of I₅₁₀/I₃₈₅ has a good linear relationship with CO in the range of 0.4-50μM.Np-CO showed good selectivity for CO and has been successfully applied for imaging of CO in onion tissue.（2）At present,there are several CO fluorescent probes designed by Pd⁰-mediated Tsuji-Trost reaction had been reported.In most of these reported probes,ester group commonly used to link allyl group（recognition group）and fluorophore.We found that ester group could be hydrolyzed by fetal bovine serum（FBS）,which is a requisite in cell culture.In order to detect CO in living cells,we designed and synthesized the organic small molecule fluorescent probe Cou-CO,which used ether group to link allyl group（recognition group）and 1,3-benzothiazol-2-yl-coumarin（fluorophore）.Cou-CO is non-fluorescence,and could react with CO under the presence of Pd⁰ to form Cou with strong fluorescence,and the maximum excitation and emission wavelengths of Cou are 464 nm and 495 nm respectively.Cou-CO showed excellent selectivity to CO and could avoid the effect of FBS with the limit of detection for CO is 78 n M.Finally,Cou-CO was successfully applied for imaging of CO in living cells.（3）Hydroxyl radical（·OH）is an important reactive oxygen species（ROS）with a very short life span and can react rapidly with many substances in biological systems.Therefore,there are great significances to develop a rapid and sensitive method for detecting·OH in biological systems.We used ethylenediamine to link 3-carboxylic acid coumarin and naphthalimide to synthesize an organic small molecule fluorescent probe Np-Cou using fluorescence resonance energy transfer（FRET）to detect·OH.Compared with 3-carboxylic acid coumarin,a fluorescent probe for detecting·OH,Np-Cou has the advantages of fluorescence red-shift,avoid the interference of bio-fluorescence,reduce light damage,large stokes shift（170 nm）and so on.Np-Cou showed high selectivity and sensitivity to·OH,and the limit of detection is 37 n M.Np-Cou was successfully applied to detect endogenous·OH in living cells.