A Novel Long-wavelength Fluorescence Probe Used For Imaging And Detection Of Active Organic Selenium And Organic Sulfur

Optical molecular imaging technology has the advantages of specific selectivity,high sensitivity,small damage to the body,easy operation,good biocompatibility,et al.and can achieve real-time tracking,monitoring and imaging of specific substances in living cells and living bodies.It is used in biomedical fields such as targeted detection of biological targets,labeling of molecular distribution,diagnosis and auxiliary treatment of diseases,and monitoring of physiological processes.The key to fluorescence imaging technology is the use of fluorescent probes for molecular response differences,as well as the interaction between substrates and receptors in disease detection and treatment for molecular recognition,and specific recognition and labeling of specific biomarkers or key molecules.Metal ions,active oxygen,active nitrogen,active sulfur and some important biological small molecules are important mediating factors.While the physiological and metabolic processes of cells change,the concentration levels and distribution of these key analytes in the cells will also Change,in turn,which affect the expression of related proteins and enzymes in the physiological process of the cell,leading to body inflammation,tissue peroxidation,DNA damage and even cancer.Therefore,it is of great significance to develop suitable small-molecule fluorescent probes to accurately detect the concentration and distribution of active molecules in cells,or to label and recognize protease,tumors,et al.At present,many literatures have reported various long-wavelength fluorescent dyes and probes for the detection and imaging applications of important analytes in physiological systems.Based on this,we have further developed new long-wavelength fluorescent probes,and investigated the analytical detection performance and application value of the new fluorescent probes in biological imaging.The following two aspects are the main research work of this paper:1.Selenocysteine（Sec,pK_a5.8）is the 21st amino acid encoded by the selenoprotein active site gene.It has a wide range of functions related to various diseases,tissues or organs and subcellular organelles.However,the cellular functions involved in many selenoproteins are still unclear.Due to the similar chemical characteristics of Sec,the biological mercaptans,such as glutathione（GSH,p K_a）8.3usually exist at high concentrations in vivo.Therefore,it is very important to develop new probes for specific detection of sec.In this paper,we control the weak acidic microenvironment to achieve high selectivity of the probe.At lysosomal p H 5.0,thiol,the main disruptor,is inert,while selenocysteine remains highly active.Because of this,in the presence of a variety of biological mercaptans and the fluorescence response is enhanced by 85times,covering a linear range from 1.0×10^-6 Mto 2.0×10^-4M,with a detection limit of 0.38μM.In addition,the probe has been successfully applied to the imaging of exogenous and endogenous Sec in lysosomes,which verifies the biological research potential of Sec in subcellular organelles.2.we constructed two probes based on the near-infrared dye semi-indole cyanine CyOH to investigate the difference in detection performance of two different hydroxyl-locking mode probes for exogenous thiophenol.The first mode probe obtained by direct connection with CyOH is named CyNO₂;while in the second mode probe,For synthesis,we first prepared a 2,4-dinitrophenyl modified benzyl bromide linker,and then modified it to the compound CyOH to obtain the probe CyNO₂.Both of these hydroxyl-locking modes can efficiently quench the fluorescence of hemicyanine fluorophores.The probe CyNO₂ is inert to important interfering substances such as GSH,Cys and Hcy in physiological systems.In addition,the probe has a wider linear detection range and lower detection limit compared to CyNO₂.Considering that the probes obtained in the first direct connection mode have been reported,in this chapter,we selected CyNO₂ for subsequent bioimaging studies and obtained satisfactory results.