Fluorescent Probes Based On Conjugated Polymers And Their Applications For Ions Detection And Bioimaging

Conjugated polymers have been widely used in optoelectronic devices and field-effect transistors due to their conductivity,flexibility and processability.In recent years,the properties of conjugated polymers,such as the strong light-harvesting,high fluorescence quantum efficiency and fluorescence signal amplification,make the polymers to be a class of potential novel fluorescent probes for biological imaging and sensing.Metal ions as environmental pollutants,enzymes and protein constituent factors in living organisms,and their content and valence changes cause serious consequences.The fluorescence properties of conjugated polymers make them show highly sensitive and selective in the fluorescent detection of metal ions.However,few highly selective and sensitive conjugated polymers-based sensors for dual-response metal ions and intracellular metal ions detection been reported,and the safety of conjugated polymer nanoparticle still need to be investigated.There are three parts of research work in this thesis,synthesis of a novel conjugated polymers-based chemosensor for high sensitivity detection of Cu²⁺and Fe³⁺,synthesis of a new conjugated polymer nanoparticles for intracellular Fe³⁺detection and development a red conjugate polymer nanoparticle probe with good biocompatibility for zebrafish microangiography.1.A novel poly?phenyleneethylene?conjugated polymer?PDBDBM?consisting of1,4-dioctyloxy-2,5-diethynylbenzene and 1,3-bis?4-bromophenyl?propane-1,3-dione units was polymerized via Pd-catalyzed Sonogashira-coupling reaction and can be used for highly selectivce and sensitive detection of Cu²⁺and Fe³⁺.And the fluorescent detection limits of PDBDBM were calculated to be 5 nM for Cu²⁺and 400 nM for Fe³⁺.Moreover,the Stern-Volmer quenching constant for Cu²⁺and Fe³⁺were found to be 1.28×10⁸ M^-1 and 2.40×10⁴ M^-1,respectively.Importantly,PDBDBM can selectively detect and quantify Fe³⁺by UV–Vis spectroscopy in Cu²⁺and Fe³⁺mixture.These results indicate the polymer can be used as a potential probe for Cu²⁺and Fe³⁺detection.2.A zwitterionic poly?arylene-ethynylene?conjugated polyelectrolyte consisting of fluorene and tetraphenylethene unit was obtained via Pd-catalyzed Sonogashira reaction.Lipid-PFTPE NPs with high fluorescence quantum yield could be obtained through nanoprecipitation method.Notably,the cell-staining efficiencies of lipid-PFTPE NPs can be enhanced by lipid encapsulation.Moreover,these nanoparticles show low cytotoxicity and high photostability,and could be endocytosed via clathrin-mediated and caveolae-mediated endocytosis pathways.Finally,the lipid-PFTPE NPs can be used as fluorescent visualizer for intracellular detection of Fe³⁺in A549 cells.3.A novel red-emission poly?arylene-ethynylene?conjugated polymer?PBPTPE?with AIE characteristics was synthesised from boron dipyrromethene?BODIPY?derivatives and1,2-bis?4-ethynylphenyl?-1,2-diphenylethene via palladium-catalyzed Sonogashira coupling reaction.The obtained polymer?PBPTPE?has typical aggregation-induced emission characteristic and an emission peak at 610 nm.The PBPTPE NPs were prepared by reprecipitation and presented excellent photostability,including superior photobleaching resistance and good stability in wide pH range.Besides,in vitro cytotoxicity and hemolysis assay indicate that PBPTPE NPs had favorable biocompatibility.Furthermore,biological evaluation and bioimaging were performed using developmental stage zebrafish embryos.From the survival and hatching rate,oxidative stress and immune-related parameters,no significant adverse effect was observed.The microangiography in zebrafish further shows that PBPTPE NPs can be used as bioprobe for in vivo applications in the future.4.Evaluation the effect of the quorum sensing signal molecule cis-2-dodecenoic acid?BDSF?against experimental vaginal candidiasis in mouse.Meanwhile,using gene knockout technology to explore the mechanism of BDSF inhibited C.albicans filament formation.