Synthesis And Properties Study Of Fluorescent Probes As Bioactive Molecular Tracers

Fluorescent probes have gradually become the main research methods and tools widely used in the detection of small biological molecules due to their diverse structures,controllable spectral properties,and high selectivity and sensitive response to identifiers.Utilizing the specific binding characteristics of fluorescent probes and the identified objects,various types of fluorescent probes can be targeted to design,which can realize the visualization of microenvironment changes,inflammation and tumors in cells and living organisms,and trace the target molecules,and then complete the optical detection of life activities and metabolic processes.In chapter two,four near-infrared hypoxic fluorescent probes based on azo reductase recognition were designed and synthesized with azo bonds as recognition groups.Among them,a prodrug nitrogen mustard was introduced in the probes SJ-OD-NJ and YL-OD to work as pharmaceutically active groups and to construct an integrated system of hypoxia recognition and in situ drug release.In in vitro experiments,Sn²⁺broke azo bonds and released fluorophores with increased fluorescence intensity,achieving 120-fold rise for SJ-OD-NJ and 150-fold rise for YL-OD.SJ-OD-NJ,YL-OD can effectively recognize and image endogenous azo reductase produced in cells and nematodes under hypoxic conditions.At the same time,YL-OD was used for fluorescence imaging of three azoreductase-rich bacteria(E.coli,S.aureus,and A.aeruginosa).Therefore,we believe that SJ-OD-NJ and YL-OD are excellent azoreductase probes,which can indirectly detect environmental hypoxia by fluorescent changes and effectively release pharmacologically active groups in situ to realize the visualization of hypoxic environment and the effect of targeted drug release.In chapter three,three mitochondrial-targeted ratiometric fluorescent probes were synthesized to monitor hypochlorous acid levels changes in living organisms.Among them,the probe BHB has excellent properties.After reacting with hypochlorous acid,the red fluorescence was quenched at 610 nm,and the blue fluorescence enhanced 40times at 460 nm.It has the advantages of high sensitivity and selectivity.In cell experiments,BHB can perform effective ratiometric imaging of exogenous hypochlorous acid with a targeted localization effect on mitochondria.The colocalization coefficient with commercial mitochondrial locator reached 0.963.The in vitro tests and biological imaging showed BHB is a good mitochondrial targeted ratiometric hypochlorous acid fluorescent probe,that can realize the visual hypochlorous acid detection both in vitro and in vivo.In previous studies,we found that prodrug pyrroluride has a good killing effect to the gold apple snails,the intermediate host of angiostrongylus cantonensis.Since the mechanism of action of pyrroluride has not been thoroughly studied,a fluorescent probe YL-LY was designed and synthesized to track pyrroluride of its distribution and metabolism inside gold apple snails by detecting the spectral signals.The fluorescent probe YL-LY showed high fluorescence intensity with stable signals in physiological conditions.Based on the successful imaging of cells and nematodes,the distributions of pyrroluride in different organs of Gold apple snails were obtained by fluorescence imaging experiments of various organ slices.Results showed that the concentration was high in the liver and was low in plantaris,and provided new optical data for exploring the distribution and metabolism of pyrroluride in Gold apple snails.In summary,a series of fluorescent probes for the detection of hypoxia,hypochlorous acid level and prodrug tracing were synthesized.It realized the detection and optical tracking of target molecules and provided new optical research methods for studying the level changes and metabolic processes of this series of biologically active small molecules.It also promoted the research and development of fluorescent probes in the field of small molecule tracking.