Design Of Fluorescent Probes Based On Indolium Hemicyanine Skeleton And Their Bioimaging Applications

Indole is a multifunctional signal molecule widely distributed in the natural environment.An exponentially growing number of researches have been reported on indole derivatives.From the viewpoint of both environmental bioremediation and biological studies,the researches on metabolism and fates of indole are important to realize environmental treatment and illuminate some biological functions.In this paper,we construct fluorescent probes based on indolium hemicyanine skeleton to realize high activity detection of cyanide,distinguishing detection of Cys/Hcy and GSH,ratio detection of hypochlorite acid and reversible cyclic detection of p H,respectively.The specific research work is as follows:1.We have developed a fluorescent probe 2-1 based on indolium hemicyanine skeleton to detect cyanide with high activity.Owing to the exceptional nucleophilicity of cyanide,the nucleophilic attack of cyanide toward the indolium group of probe 2-1 would block ? conjugation between indolium and coumarin,resulting in the color of the solution changing from blue to yellow-green under naked eye observation,and the fluorescence of the corresponding system also increased significantly.In addition,probe 2-1 had high selectivity and sensitivity to CN-,its detection limit was found to be 0.066 ?M and the reaction time was 100 s.Moreover,the cellular imaging experiments further confirmed that probe 2-1 had good cell membrane permeability.2.We have developed a near infrared fluorescent probe 3-1 based on indolium hemicyanine skeleton with three potential thiol binding sites for simultaneous sensing Cys/Hcy and GSH.In the design of probe,we not only constructed three potential binding sites,but also introduced a near-infrared fluorophore,which enabled probe 3-1 to not only effectively distinguish Cys/Hcy and GSH,but also achieve fluorescence imaging of biothiols in vivo.3.We have developed a NIR ratiometric fluorescent probe 4-1 based on indolium hemicyanine skeleton to detect endogenous hypochlorous acid.Herein,we employed cyanine dyes as a NIR fluorophore and constructed two reaction sites in the probe for detecting HCl O.The probe 4-1 has fast response time,long emission wavelength and dual fluorescence emission channels for detecting HCl O.Moreover,the probe 4-1 was successfully applied for detection of endogenous hypochlorous acid in Hep G-2 cells and Cl O-level in 84 disinfectant.4.We have developed a NIR ratiometric fluorescent probe 5-1 based on indolium hemicyanine skeleton to detect p H.Herein,we used a spiropyran as a p H reaction site for closed-loop to open-loop reaction.When the p H was decreased from 9.0 to 1.0,the color of probe 5-1 solution change from purple to yellow was found by naked eye.The probe was sensitive to acidity,and the p Ka of probe was calculated to be 4.85.The conversion between acid and alkaline form of the probe 5-1 was reversible and rapid by adjusting the p H value of the solution system.As a fluorescent sensor for assessing p H change in real time,probe 5-1 can be used for real-time monitoring of intracellular p H.