Fabrication Of Polvaniline And Its Derived Functional Materials For Bioanalysis

Efficient method for isolation and detection of CTCs is of great significance for cancer diagnosis and therapy in the early stage.Traditional technologies for detection and isolation of CTCs are established based on the physical or chemical properties of the cells,such as size,density,charge or cell adhesion molecules expressed on surface of cancer cells.However,the capture and isolation efficiencies of these methods are relatively low,and they could not meet the practical application for sensitive detection of CTCs in human blood because of the extremely low concentration of CTCs in the peripheral blood of patients.The morphology of nanostructures and the surface chemistry of the interfaces significantly influence the capture and isolation efficiencies of CTCs.Polyaniline materials due to their easy synthesis,controlled morphology of nanostructures,low cost,good stability,excellent biocompatibility and matched mechanical properties to the microstructures on the surface of the cells,have been widely used in tissue engineering and bioanalysis.However,the low solubility of polyaniline,the poor processibility,the complicated modification process of the polymer surface,and the low conductivity in neutral condition hinder the further application of polyaniline in bioanalysis.In this doctoral thesis,we will focus on the fabrication of polyaniline and its derivatives with controlled morphologies and tunable surface chemical properties for capture and isolation of CTCs with high efficiencies.Finally,carbonization of polyaniline will be used to prepare nitrogen doped graphene modified electrode for electrochemical detection of radicals with high sensitivity.Detailed introductions are listed below:1.Morphology controlled poly(aminophenylboronic acid)nanostructures as smart substrates for enhanced capture and release of circulating tumor cellsA simple and template free method to synthesize boronic acid derivative polyaniline(PANI)bioinspired nanostructures with controlled morphology is established.Different nanostructured morphologies such as nanotexture,nanofibers,nanoparticles,microsphere,and 3D porous network have been prepared by controlling the nucleation and growth rate for polymerization.The prepared poly-APBA nanostructures show enhanced capture and release efficiencies toward CCRF-CEM due to the synergistic effect of topographical interactions and phenylboronic acid functional group on the nanostructures.Capture efficiency as high as 78.3%can be achieved.Meanwhile,the phenylboronic acid functional groups on the surface of the nanostructures during polymerization are used as the artificial lectins to reversibly capture and release of CTCs with little damage to the cells.2.Electrochemically controlled capture and release of circulating tumor cells based on the oxidation of boric acid estersWe propose an efficient,selective and electrochemical controlled method for capturing and releasing circulating tumor cells(CTCs)based on the oxidation of boric acid esters.Boronic acid derivative,poly-(3-APBA-co-2-ABSA)is obtained by copolymerization of 3-ABPA and 2-ABSA.The conductivity of the conducting polymer in neutral condition is improved by sulfonic acid self-doping.Dopamine is covalently bounded to the polymer in neutral conditions through the formation of borate ester bond between phenylboronic acid functional groups on the polymer surface and the diols of dopamine.Sgc8c aptamers are further modified to the polymer surface by the amino group of dopamine to improve the selectivity for capture of CTCs.An efficient and rapid cell release process can be achieved by electrochemically oxidizing the borate ester bond formed between phenylboronic acid and dopamine.3.A rapid and sensitive method for hydroxyl radicals detection on a microfluidic chip using an N-doped porous carbon nanofiber modified pencil graphite electrodeWe present a simple and sensitive method for the detection of hydroxyl radicals(·OH)on a microfluidic chip using an electrochemical technique.Aniline monomer is electrochemically polymerized on the surface of a pencil graphite electrode and carbonized at 800 ?.The resulting N-doped porous carbon nanofiber-modified pencil graphite electrode is embedded into a microfluidic chip directly as a working electrode.4-Hydroxybenzoic acid(4-HBA)is selected as the trapping agent of ·OH.The microfluidic chip is successfully utilized for the indirect detection of ·OH in cigarette smoke by detection of the tapping product of 3,4-dihydroxybenzoic acid(3,4-DHBA).