Synthesis, Characterization, And Biosensing Applications Of Cationic Water-Soluble Poly(aryleneethynylene)s

In recent years, water-soluble conjugated polymers (WSCP) have been used as chemical and biological sensors due to their unique optical and electrical properties. Because of WSCP is soluble in water and other environment-friendly solvent, micro substances can be detected through between the polymer and the oppositely charged-quencher. Hence electronic or energy transfer tends to delocalize easily throughout the polymer chain and fluorescence quenching signal is amplified, thus high-sensitivity detection of a variety of organic or inorganic and even biological macromolecules can be easily achieved. From the structural design of point, the multi-branched WSCP can improve the self-quenching of fluorescence causing by configuration compared to the linear WSCP. Consequently, the anti-interference ability and detection sensitivity can also be increased when WSCP is applied as sensory materials. On the other hand, as sensing materials with high sensitivity, WSCP has the advantages of real-time and signal-amplified in the detection of the enzyme using. As a result, the enzyme assay high sensitivity, convenience and wide-spectrum can all be achieved by WSCP. In the thesis, we prepared multi-branched water-soluble conjugated polymers first, besides this, we have designed a novel sensing method using of cationic water-soluble conjugated aromatic acetylene which has been obtained. This dissertation is focused on modifying the aggregation of WSCPs by means of structure design and changing environmental conditions, and studying the structure-property relationship. The contents are as follows:1. Hyperbranched reaction method is introduced to the design of water-soluble conjugated polymer synthesis. The synthesis of water-soluble conjugated hyperbranched polymer was adopted A2 + A2' + B3 method. At first, ABn monomer with conjugated aromatic structures was synthesized and then polymer was obtained by one-step reaction. In the beginning, the neutral polymer was gained through Sonogashira polymerization, and then got water-soluble conjugated polymers from post-quaternization treatment.2. The cationic conjugated polymer (CCP) associated with the fluorescein-labeled anionic adenosine triphosphate (ATP) by electrostatic attractions and fluorescence resonance energy transfer (FRET) from the CCP to the fluorescein-labeled ATP occurred. When phosphatase was added, it catalyzed the hydrolysis of phosphate groups from its substrate, ATP, and the final product adenosine was neutral, which made the CCP detached from adenosine. Then the FRET efficiency decreased. The results showed that the degree of FRET efficiency decrease was related to the concentration of phosphatase, the detection limit can be 1×10-6 unit/μL.