The Development Of Antifouling Sensor Based On Novel Functional Polymer In Complex Sample

The compositions of biological samples such as blood are very complex, and during electrochemical measurements the nonspecific adsorption of protein on the sensing interface can cause a series of problems, such as high background noise, low sensitivity and even short sensor life time. Therefore, the development of novel antifouling interfaces to achieve high sensitivity, high selectivity and rapid response to the target in complex samples has attracted more and more attention in recent years. The main contents of this thesis are summarized as follows:(1) A facile electrochemical method was developed for the synthesis of a novel nanocomposite of gold nanoparticles(Au NPs) doped conducting polymer poly(3, 4-ethylenedioxythiophene)(PEDOT). The PEDOT/Au NPs nanocomposite was prepared through the one-step electrochemical polymerization of 3, 4-ethylenedioxythiophene(EDOT) in an aqueous solution containing Au NPs colloid. The obtained PEDOT/Au NPs composite possessed good conductivity and exhibited a 3D porous network microstructure owing to the presence of Au NPs, which not only acted as highly conductive dopants, but also as ‘templates’ for the growth of the conducting polymer. Based on the unique property of the nanocomposite, the PEDOT/Au NPs modified electrode exhibited excellent catalytic activity towards the electrochemical oxidation of nitrite. The modified electrode is capable of detecting nitrite in the 0.2 to 1400 μM concentration range, with a detection limit of 60 n M.(2) A novel conducting polymer composite, poly(3,4-ethylenedioxythiophene)(PEDOT) doped with bovine serum albumin stabilized Au nanoclusters(Au NCs), was successfully synthesized through electrochemical polymerization in a solution containing 3,4-ethylenedioxythiophene(EDOT) monomer and Au NCs. The obtained Au NCs doped PEDOT(PEDOT/Au NC) composite possessed a unique microstructure with Au NCs evenly distributed within the PEDOT film as dopants. The PEDOT/Au NC modified electrode exhibited large effective surface area and high electrocatalytic activity toward nitrite oxidation, and it was further developed into a highly sensitive electrochemical sensor for nitrite. Under optimum conditions, the linear range of the sensor was from 0.05 to 2600 μM, with a very low detection limit of 17 n M(S/N = 3).(3) A biosensor for the electrochemical monitoring of breast cancer biomarker BRCA1 was developed based on polyethylene glycol(PEG)modified gold electrode(GE). Because of the excellent hydrophilicity of PEG, the fabricated biosensor exhibited good antifouling ability, and it is capable of detecting BRCA1 in 5% human serum samples. Moreover, the developed biosensor can be label-free for the detection of BRCA1 using electrochemical impedance spectroscopy(EIS). The linear range of the sensor was from 1.0 f M to 1 n M, with a very low detection limit of 0.37 f M(S/N = 3).(4) An unique antifouling sensing interface based on two hydrophilic polymers, tannic acid(TA) and polyethylene glycol(PEG) was constructed. A novel composite of the poly(3,4-ethylenedioxythiophene)- tannic acid(PEDOT-TA) was synthesized through electrochemical polymerization. Subsequently, PEG was immobilized on the composite via hydrogen bond formation, which showed a water contact angle of 29°, indicating good hydrophilicity. Alpha fetoprotein(AFP) antibody, a vital tumor biomarker for liver cancer, was then immobilized on the electrode surface to develop a biosensor for AFP. The fabricated biosensor exhibited favorable selectivity, high sensitivity and ultralow detection limit. The linear range was from 1.0 fg/m L to 0.1ng/ m L, with a very low limit of detection of 0.34 fg/m L(S/N = 3).