Preparation And Electrochemical Biosensing Application Of Conducting Polymer Nanowire Based Composite Materials

In this thesis,different conducting polymer nanowire composites were prepared using electrochemical polymerization method.Based on these nanocomposites,several electrochemical biosensors were constructed for the sensitive and selective detections of different disease biomarkers.The microstructures,biosensing performances and antifouling properties of these nanocomposite modified electrodes were characterized with various technologies,such as SEM,XPS,EIS and DPV.It is expected that these novel biosensing platforms may find potential applications in clinic diagnosis.The main research contents of this thesis are summarized as follows:?1?A novel electrochemical immunosensor based on the hybrid composite of PEG/AuNPs/PANI was successfully developed,where the composite was electrochemically synthesized polyaniline?PANI?nanowires functionalized with gold nanoparticles?AuNPs?and polyethylene glycols?PEG?.The prepared PEG/AuNPs/PANI composite,combining the good electrical conductivity of the AuNPs/PANI with the excellent antifouling ability of PEG,offered an ideal substrate for the development of low fouling electrochemical biosensors.Alpha-fetoprotein?AFP?,a well-known hepatocellular carcinoma biomarker,was used as a model analyte,and its antibody was immobilized on the PEG/AuNPs/PANI for the construction of the AFP immunosensor.Using the redox current of PANI as the sensing signal,in addition to the good biocompatibility of PEG/AuNPs and the anti-biofouling property of PEG,the developed immunosensor showed excellent biosensing performances,such as wide linear range and ultralow detection limit(0.007 pg mL^-1).?2?A reagentless and label-free voltammetric immunosensor was developed for the detection of carcinoembryonic antigen?CEA?,an important biomarker for colorectal adenocarcinoma.It is based on the use of a hybrid composite consisting of polyaniline?PANI?nanowires grown on the conducting polymer poly?3,4-ethylenedioxythiophene??PEDOT?that was doped with an ionic liquid?IL?.The composite possesses excellent electrical conductivity and a porous structure,a high specific surface area and inherent redox activity.Antibody against CEA was immobilized on the surface of the composite modified glassy carbon electrode?GCE?to construct an immunosensor.This immunosensor displays a linear range of 0.001-10 ng mL^-1,with a detection limit as low as 0.7 pg mL^-1.It also possesses excellent stability and selectivity.?3?In this work,a novel electrochemical biosensor based on the cleavage of a specific peptide for sensitive analysis of prostate specific antigen?PSA?was developed.Polypyrrole?PPy?nanowires were synthesized in phosphate buffer solution using electrochemical method.AuNPs were then assembled on PPy nanowires for the subsequent binding of peptide that can be specifically cleaved by PSA.The prepared peptide/AuNPs/Ppy composite modified electrode,combining the good electrical conductivity of the AuNPs/Ppy with the excellent antifouling ability of peptide,offered a wonderful substrate for the development of low fouling electrochemical biosensors.In the presence of PSA,the peptide was specifically recognized and cleaved,and the resulting electrode impedance change can be used for the assay of PSA.Under optimal conditions,the developed biosensor exhibited a wide linear range from 0.00001 to 10 ng mL^-1.