Synthesis Of Fluorescent Probes For Detecting Intracellular HClO And GSH And Their Bioimagin

Reactive oxygen species（ROS）and reactive sulfur species（RSS）were responsible for intracellular redox homeostasis,and their imbalance could lead to a series of physiological diseases,such as cardiovascular diseases,inflammation and cancer.Therefore,real-time detecting of bioactive small molecules was of great significance for the prevention and treatment of diseases.Compared with traditional electrochemical method,high-performance liquid chromatography and mass spectrometry,fluorescence microscopic imaging method had become an effective way to detect bioactive small molecules and it was an urgent task to develop fluorescent probes with high sensitivity,good specificity,stable structure and fast response.In this paper,two types of fluorescent probes were synthesized to detect HClO and GSH in cell.The details are as follows:1.A fluorescence probe based on electrophilic aromatic chlorination for imaging and monitoring of cellular HClO.In this work,we synthesized the meso-pyridine-substituted BODIPY fluorescent probes called PB-C_R.Fluorescence titration experiment indicated that PB-C_Rshowed an excellent selectivity towards HClO over other ROS.The mechanism study revealed that the recognition reaction type was specific chlorinated reaction based on BODIPY 2,6 position.R=CH₃CH₂,PB-C₂could be applied to detect cellular HClO and MPO activity.R=CH₃（CH₂）₁₇,the probe PB-C₁₈adhered to the membrane surface due to strong hydrophobic effect.Upon addition of HClO,the probe labeled on the membrane could actively respond to hypochlorite and appeared fluorescent enhancement.PB-C₁₈not only exhibited an obviously fluorescence-enhanced response with the exosomes,but also showed a dramatic response to HClO.Furthermore,the probe was employed in imaging the endogenous and exogenous HClO in RAW 264.7 cells.2.A reversible fluorescence probe for quantitative imaging and dynamic monitoring of cellular glutathione.Since the concentration of GSH in the cell was far beyond the concentration of the probe that the cell can tolerate,only a few probes had been successfully developed to quantitively monitor GSH variations.Here,we introduced a sulfur atom at theα,β-unsaturated carbonyl moiety instead of oxygen atom in our previous work to construct the probe QG-S.The pure major E-isomer was further determined by single crystal diffraction.Due to the PET effect of sulfur atom,the probe had weak fluorescence.Upon gradual addition of GSH to QG-S,the variation was attributed to the interrupt of intramolecular charge transfer（ICT）process of QG-S through breaking the conjugatedα,β-unsaturated carbonyl moiety,resulting in the recovery of the green fluorescence with an off-on fluorescence response.The probe showed extremely low cytotoxicity and determined the GSH concentration to be 4.25 mM in Hela cells.