Studies On Merocyanine Derivatives As Fluorescent Molecular Probes

Active small molecules are closely related to a wide range of physiological processes in the organism.Biologically active molecules such as active sulfur and active oxygen species play a vital role in physiological and pathological processes.These actice molecules are related to a variety of human diseases,including cancer and neurodegenerative diseases.Therefore,the accurate detection of active sulfur and active oxygen is helpful to clarify their correlation with disease.Different from the traditional detection methods,the fluorescence analysis has the characteristics of good reproducibility,fast detection and biocompatibility.And the special reaction of fluorescent probes to active sulfur and active oxygen can achieve high accuracy degree detection.With the development of research on these active small molecules,the requirements for fluorescent probes are getting higher and higher.When dealing with actual needs,some shortcomings of fluorescent probes themselves will still be exposed.Therefore,the development of a novel fluorescent probe,which has better optical properties and fit in the higher requirements of scientific research,is an urgent problem to be solved.Fluorescent probes designed based on cyanine-type signal units are widely used in biochemical analysis and in vivo imaging due to their near-infrared emission penetrating ability and insusceptibility to biological fluorescence interference.However,cyanine-based fluorophores have problems such as poor light stability and small Stokes shift.In this study,in order to improve the optical stability of the probe and apply the probe to the deep imaging of living tissue,a new mesocyanine fluorescence probe based on the structure of cyanine group was designed and synthesized.It is expected to provide a new idea and method for the research and development of this kind of probe.The content of work is as follows:?1?A fluorescent probe P-Cy specifically detecting cysteine?Cys?was designed using the existing structure Cy-Ph as a fluorophore.Due to the photoinduced electron transfer mechanism?PET?,the fluorescence of the probe itself is quenched.After binding to cysteine,the PET is blocked,allowing the fluorescence of the probe itself to recover.Experiments have confirmed that the fluorescence intensity of P-Cy is continuously enhanced at 557 nm when the cysteine concentration is increased.At the same time,the probe has high selectivity to cysteine and achieves fluorescence imaging of A549 cells and fluorescence imaging in mice.?2?Based on the existing structure Cy-NH₂,we designed a fluorescent probe Cy-An that specifically detects singlet oxygen?¹O₂?.The probe itself has strong fluorescence.When combined with singlet oxygen,the fluorescence of the probe at 725 nm gradually decreases.It was confirmed in the experiment that the probe can detect singlet oxygen quickly with high selectivity.