Developing Naked-eye And Mitochondria-targeted Fluorescent Probes For Sensing Biothiols And Hydrogen Peroxide Based On A Coumarin-hemicyanine Hybrid

The fluorescence detection method has the advantages of high sensitivity,strong visibility,simple operation,good selectivity,low cost,and small cell damage,and it is an indispensable detection method in the fields of life sciences and biological analysis.Coumarin compounds are often used as fluorophores due to their good photostability,high fluorescence quantum yields,and large Stokes shifts.Herein we constructed a coumarin-hemicyanine hybrid（CHM-OH）,which was used to develop two fluorescent probes for sensing mitochondrial biothiols and hydrogen peroxide（H₂O₂）with good optical properties.The main contents are summarized as follows:（1）Mitochondrial biothiols such as cysteine（Cys）,homocysteine（Hcy）and glutathione（GSH）are crucial to maintain redox homeostasis of mitochondriain,and play vital role in a wide range of physiological and pathological processes.Therefore,develop fluorescent probes for sensing mitochondrial biothiols is of great significance in life sciences and biological analysis.We designed a new fluorescent probe（CHM1）composed of CHM-OH as the fluorescence reporter,an acrylate moiety as the Cys response site,and a 3H-indol-1-ium moiety as the mitochondria-targeted carrier.This probe is capable of sense selectively biothiols with the response time of 5 min and the detection limit of 0.27μM in the case of Cys.Additionally,addition of Cys to the probe induced a visible color change from pale yellow to purple,facilitating a naked-eye observation.This probe was successfully applied for imaging Cys in He La cells.（2）Monitoring H₂O₂ produced from mitochondria using fluorescent probes has attracted much attention on account of its physiological and pathological functions.We designed a new fluorescent probe（CHM2）based on the CHM-OH fluorogen bearing a 3H-indol-1-ium moiety as the mitochondria-targeted carrier by incorporation of a boronate-based molecule switch.In PBS（10 m M,p H=7.4）,this probe can selectively detect H₂O₂ without interference from other analytes with the response time of 20 min and the detection limit of 1.63μM.This probe demonstrates desired properties such as a naked-eye observation,a turn-on red fluorescence response,excellent water solubility and so on.Fluorescence colocalization studies reveal that it can effectively target the mitochondria of He La cells and is sensitive to the exogenous and endogenous generation of H₂O₂.