Preparation Of Organic Conjugated Polymer Nanoparticles For Intracellular PH Detection And Antibacteria By Photodynamical Therapy

In recent years,conjugated polymer nanoparticles have attracted more and more researchers' research interest due to their excellent optical properties.As a new type of fluorescent material,conjugated polymer nanoparticles have the advantages of small size,high luminous intensity and low toxicity.At the same time,the conjugated polymer chain has a large number of photoactive units with a high molar extinction coefficient.Based on the above excellent performance,it has shown its broad application prospects in the fields of analytical chemistry/medicine,and environmental monitoring.It has been widely used in cell imaging,biomolecular detection,in vivo imaging and optical therapy.At the same time,using the strong absorption ability of organic semiconductor and the characteristics of fluorescence resonance energy transfer,the prepared photosensitizer-doped semiconductor nanoparticles can effectively enhance the photodynamic efficiency of the photosensitizer and have strong antibacterial properties.The purpose of this thesis is to use conjugated polymer nanoparticles as the fluorescence sensing material to prepare a pH nanoprobe with excellent optical performance and high stability through a reasonable design scheme,and realize the ratio of pH value in aqueous solution and in the cell.Response detection.At the same time,the small molecule photosensitizer porphyrin is doped into the conjugated polymer nanoparticles,and the high-efficiency photodynamic antibacterial material is prepared by utilizing the effective energy transfer characteristics from the conjugated polymer to the porphyrin.The main research contents are as follows:(I)Design of a novel conjugated polymer two-photon fluorescent probe and its application in pH detectionIn this chapter,PSMA(styrene-co-maleic anhydride)modified polyfluorene vinyl polymer PFV two-photon nanoparticle was prepared by coprecipitation method.Dopamine(DA)molecules with pH response characteristics were attached to the surface of PFV / PSMA NPs nanoparticles using an amide condensation reaction for pH response and bioimaging.Quantitative determination of pH changes in HeLa cellsand detection of pH fluctuations under different stimuli by single photon and two-photon fluorescence imaging(II)Design and cell imaging of core-shell conjugated polymer pH probe based on FRET mechanismIn this chapter,a conjugated polymer nanoprobe(PFO / PFV-DA NPs)with a core-shell structure was designed to detect the intracellular pH.The central polyfluorene PFO acts as a donor,and PFV acts as a receptor,forming a nuclear and shell structure in space.The thicker shell PFV envelops the nuclear PFO,which can significantly reduce the interference of dopamine on the emission quenching of nuclear PFO,so that dopamine with corresponding pH characteristics is only sensitive to shell PFV.At the same time,through comparative experiments,it was found that the core-shell PFO / PFV-DA Nps is more stable in structure and optics,and the former does not produce photobleaching and leakage compared with the conjugated polymer nanoparticles doped with small molecule fluorescent dyes.problem.Finally,the ratiometric quantitative determination of pH changes in HeLa cells and the detection of pH fluctuation under different stimuli were successfully achieved by two-channel fluorescence imaging.(III)Enhanced Photodynamic Antibacterial Study of Siloxane and Conjugated Polymer Nanoparticles Based on SilsesquioxaneIn this chapter,we synthesized a porphyrin material with a silsesquioxane(POSS)structure,and then obtained a conjugated polymer by coprecipitation with a conjugated polymer PFV and a sesquiion structure Porphyrin-Poss.Nanoparticles,using efficient energy transfer from conjugated polymer to porphyrin,achieve high-efficiency photodynamic antibacterial,and are characterized by DLS,TEM,UV-PL.Singlet oxygen-killing Gram-positive bacteria(Staphylococcus aureus)and Gram-negative bacteria(Escherichia coli)under a certain power of white light,compared with general porphyrin photodynamic antibacterial materials,including Poss structure The nanoparticles produce a higher yield of singlet oxygen and better stability.