Construction Of Small Molecule Near-Infrared Fluorescent Probe And Its Application

Owing to the advantages of high sensitivity,good selectivity,simple operation,fluorescent probes have important applications in the fields of chemistry,biomedicine and clinical diagnosis.In order to be better applied to biological systems,the development of near-infrared fluorescent probes with long emission wavelength?650-900 nm?,strong tissue penetrating ability,small cell damage and small autofluorescence interference has attracted wide attention of scientists.In the paper,two near-infrared fluorescent probes were developed to detect biothiols and SO₂ derivatives,and they were successfully applied to fluorescence imaging of cells and zebrafish.The specific research contents are as follows:1.A new near-infrared?NIR?fluorescent probe 2-1 based on 2-Methylchromone was exploited for specific recognition of Cu²⁺and biothiols.Probe 2-1 showed a fluorescence emission band at 718 nm in PBS-EtOH?3:2,v/v,10 mM PBS,pH 7.4?solution.Upon the addition of Cu²⁺,a large fluorescence quenching was observed due to the coordination between probe 2-1 and Cu²⁺.After adding GSH to the system,the biothiols has a strong affinity with Cu²⁺,and a displacement reaction occurs,and red fluorescence is recovers.This“on-off-on”fluorescent probe was also successfully applied to image GSH in MCF-7 cells and zebrafish.2.A near-infrared?NIR?fluorescent probe 3-1 for detection of SO₂ derivatives was developed based on conjugated hybrid coumarin-hemicyanine,which not only can specifically recognize SO₂ derivatives,but also has low detection limited to 1.22?M,short response time of 5 min.Probe 3-1 showed a fluorescence band at 749 nm in HEPES buffer?10 mM,pH 7.410%DMF,v/v?.Upon the addition of HSO₃^-,a nucleophilic addition reaction occurs in the carbon-carbon double bond of HSO₃^-and probe 3-1,destroying the conjugated system in the molecule,and the fluorescence emission peak is blue-shifted to 490 nm,and a Stoke shift of259 nm occurs,and the fluorescence color changes from red to green.By fluorescence colocalization experiments,it was determined that the probe has a mitochondrial targeting function and can be used to detect the level of SO₂ derivatives in the mitochondria of cells.