Studies On Functionalized Water-soluble Conjugated Polymers:Synthesis, Photophysical Properties And Applications In Sensors

In recent years, water-soluble conjugated polymers (WSCPs) have been widely used in the field of biological sensing, diagnosis and bioimaging due to their unique optical and electrical properties as well as water-soluble characteristics. Bio-functionalized or chemical functionalized conjugated polymers contain special functional groups such as glycosyl, biotin. amino acid, peptide, nucleic acid and antibody, which endow them strong capacity to recognize biomolecules and heavy metal ions, further broaden the application of conjugated polymers in the field of biological and chemical analysis.In this thesis, two functionalized conjugated polymers have been prepared by doping certain groups into PPE main chain and modifying the side chain. Preliminary biochemical analysis applications have been explored by studying the photophysical properties. The contents are as follows:1. A biotinylated water-soluble conjugated polymer with blue emission characteristics has been synthesized, which contains fluorenyl alkynyi-benzene main chain structure. At first a neutral non-functionalized conjugated polymer was obtained through Sonogashira reaction, then followed by post-functionalization, which including modification of its side chains with biotin and post-ionization. It can be dissolved in the polar organic solvent (such as DMSO or methanol), but a little in water.2. PFPNBr-biotin is characterized by FT-IR, UV-vis absorbance sprectra and fluorescence spectra. By detecting the photoluminance spectra in different conditions (different concentrations, different methanol-water mixed solutions, as well as different pH solutions), photophysical properties of PFPNBr-biotin are studied. The results show:1) When the concentration range from100μM to400μ.M, the fluorescence intensity of PFPNBr-biotin increases gradually with the increasement of its concentration. When the concentration exceeds400μM, the fluorescence emission intensity tends to become weaker with the increasement of its concentration;2) PFPNBr-biotin can be uniformly dispersed in methanol. Along with the increase of water proportion in the methanol solvent, the fluorescence emission intensity become weaker. When the ratio of methanol to water reaches1, the fluorescence is quenched almost completely;3) When the ratio of methanol to water is4, PFPNBr-biotin shows a certain dependence on the pH value. The maximum fluorescence intensity is observed at pH5. and the fluorescence intensity at pH7is the weakest.3. Through the introduction of benzoselenazole unit into the fluorenyl alkynyl-benzene main chain structure, the conjugated polymer functionalized with amino protected by tert-butyl ester PFBTP-Boc has been obtained. PFBTP-Boc emits green fluorescence because of the high efficient energy transfer between main chain groups. Monomer M2with amino protected by tert-butyl was synthesized first, then PFBTP-Boc was obtained by Sonogashira polymerization among M1, M2and M3. Influence of many metal ions on the photophysical properties of PFBTP-Boc has been studied, which demonstrate that PFBTP-Boc has a good ability to resist the interference of many metal ions.4. The applications of PFPNBr-biotin in chemical and biological sensing have been explored, which including the detection of proteins and the metal ions. The conclusions are as follows:1) PFPNBr-biotin shows an excellent ability to recognize streptavidin specifically at both pH7and pH9;2) The influence of metal ions on the fluorescence emission intensity of PFPNBr-biotin has a certain dependence on pH values. When pH is9, the fluorescence emission intensity of PFPNBr-biotin enhances with the addition of metal ions;3)Adding streptavidin into PFPNBr-biotin can improve the detection ability to Ni2+at pH5. Furthermore, PFPNBr-biotin has been marked onto the alpha-fetoprotein antibody AFP by specific binding between biotin on the side chain of PFPNBr-biotin and streptavidin modified on the alpha-fetoprotein antibody AFP. PFPNBr-biotin shows amazing potential application as a fluorescent reporter for tagging tumor markers, which can be used for the detection of antigens and tumor markers.