Construction Of Near Infrared Fluorescent Probe And Its Application In Biochemical Analysis

Compared with traditional fluorescent probes,near-infrared（NIR）fluorescent probes have unique advantages in tracking molecular processes in vivo and in vitro due to their less damage to living cells,better tissue penetration and minimal interference from background autofluorescence.There are no doubt that near-infrared fluorescent probes will provide more opportunities for chemists and biologists to conduct research to better understand biological processes at the molecular level.In this thesis,three kinds of near-infrared fluorescence probes are constructed for the detection of small molecules in organisms and the tracking and positioning of organelles.The details are as follows:（1）Reactive oxygen species（ROS）play key roles in various signal transduction and pathological processes and are essential to human life.In this section,a p H-sensitive fluorescent probe is proposed,which has superior selectivity for peroxynitrite（ONOO^-）under acidic conditions,hypochlorite ions（Cl O^-）under neutral conditions and singlet oxygen（¹O₂）under alkaline conditions,respectively.It is suitable for the detection of various ROS in various p H environments.And the probe has been shown to be feasible at the cellular level,showing accurate near-infrared ratiometric fluorescence imaging of exogenous and endogenous ROS.（2）Rheumatoid arthritis（RA）is an autoimmune disease characterized by erosive arthritis.ONOO^-is an important member of ROS.It exists widely in organisms and participates in various physiological processes.Studies have shown that ONOO^-is directly involved in tissue damage in patients with RA.Here,this section proposes a dual-responsive near-infrared receptor,Lyso-Cy,capable of visualizing p H and ONOO^-.p H-dependent spectroscopy（p Ka=5.81）and lysosome targeting groups give Lyso-Cy a near infrared emission indication in the lysosome.Furthermore,it showed a good proportional measurement pattern for ONOO^-in lysosome.In addition,this double-response receptor has also been shown to be suitable for mouse models with arthritis,with the ratio curve as a response,showing potential applications in early RA diagnosis and clinical treatment monitoring.（3）Lipid droplet（LDs）is more closely related to endoplasmic reticulum（ER）than other organelles.LDs originate from ER,and the endoplasmic reticulum contains most of the enzymes required for neutral lipid synthesis.Defects in the LDs-ER interaction can lead to serious diseases,including lipodystrophy and neurological disorders.Thus,visualizing the interaction between LDs and ER is critical to elucidating and revealing the underlying mechanisms in biology and pathology.Herein,we explore a two-color near-infrared fluorescent probe Cy-Rh that can simultaneously display both LDs and ER organelles.The emission color of Cy-Rh can be switched between red and NIR by reversible cyclization reaction,and the emission color is related to water content.Inside the cell,the core of LDs is highly hydrophobic and contains litter water,while the ER membrane is loose and contains a large amount of water.Therefore,the probe can be realized to label ER and LDs in red and NIR fluorescence respectively.