Construction Of A Novel Probe For Detecting Mitochondrial Microenvironment And Its Application In Bioimaging

The fluorescence technology has been widely used by scientists due to its high sensitivity,specificity,simple technology,and non-invasiveness.In recent years,with the rapid development of fluorescent probes,more and more probes have been exploited,which are widely used in environmental test,life science,materials engineering and other fields,becoming a significant analytical tool.Mitochondrial are recognized as the main subcellular organelle of eukaryotic cells and participate in various physiological activities such as energy providing and normal cell metabolism maintaining.Therefore,the design and development of novel probes for detecting mitochondrial micro-environment are of great significance for the study of various diseases and dysfunctions.In this work,coumarin and merocyanine were selected as fluorophores to construct a novel mitochondrial-targeted organic small molecule fluorescent dye and two fluorescent probes,which can identify the changes of micro-viscosity in mitochondrial and the levels of H₂S in cells,respectively.The research contents are showed as follow:（1）A novel merocyanine-structured mitochondrial dye Mito-ql was constructed by using coumarin as the fluorescence platform and quinoline quaternary ammonium salt as the mitochondrial-targeted moiety.The coumarin moiety was used to the electron donor and quinoline quaternary ammonium salt was as the electron acceptor,which were linked by a C=C bond to form the fluorescent dye with ICT progress.Due to the electronegativity of the mitochondrial membrane structure,the dye Mito-ql can target mitochondrial through electrostatic interactions.Mito-ql has excellent optical properties and a large Stokes shift（165 nm）resulting in potentially monitoring the dynamic changes of the micro-environment in mitochondrial.（2）A novel near-infrared viscosity-responsive fluorescent probe,Mito-DF,was constructed by using the indole group as the electron-donating group and the quinoline quaternary ammonium salt as the electron-withdrawing group.This probe has excellent spectral properties,the logarithm of its fluorescence intensity is linearly correlated with the logarithm of viscosity change.Mito-DF can perform fluorescence imaging of viscosity changes in living cells and zebrafish,as well as can realize inflammation detection in tissues and organisms.（3）The NIR fluorescent probe Mito-HS was constructed based on the nucleophilicity of H₂S.H₂S first undergo a nucleophilic addition reaction with the C=C double bond of the probe Mito-HS,and then the-SH group undergoes a nucleophilic substitution with the chlorine atom to form a stable five-membered ring,the conjugated system is destroyed as a result in the fluorescence quench.The probe Mito-HS has brilliant optical properties and can effectively gather in mitochondrial to detect changes of H₂S concentration.In addition,the probe was also enabled to the detection of H₂S level in zebrafish.