Construction Of Electrochemical Biosensors Based On Carbon Nanomaterials And Their Application In Biological Analysis

Nanomaterials based on one-dmensonal carbon nanotubes (CNTs)and two-dmensonal graphene have attracted increasing attention fromscientists. And they are the ideal materials for constructingelectrochemical biosensors due to excellent electrical, mechanical,thermal, biocompatible properties, large specific surface and excellentsignal integration amplification. Therefor, in this thesis, we havedeveloped several immunosensors based on single-walled carbonnanotubes (SWCNTs) and graphene oxide (GO), and applied inbiological molecules of high sensitive and selective detection. Whichhave brodened the application of carbon nanomaterials. The maincontents are shown as follows:(1) A label free impedance immunosensor based on Aunanoparticles and super-long SWCNT array was developed. Horizontallyaligned SWCNT array was produced on SiO2/Si wafers by the chemicalvapor deposition (CVD) method, then depositing gold nanoparticles onthe as-prepared SWCNT array by electrochemical method, and followedby self-assembling anti-IL-6antibody to build sensing electrode. Theas-prepared label-free sensor exhibits ultrahigh sensitivity, goodanti-interference and great selectivity in serum samples. The detectionlimit is experimentally found to be lower than0.01fg mL-1, which issignificantly lower than the normal IL-6concentration.(2) A label free electrochemical immunosensor was constructedbased on Au nanoparticles and graphene oxide modified electrode. Thesensing electrode was fabricated based on good biocompatibility, largespecific surface and good visualization for biological molecules of Au NPs, and based on the carboxyl group of graphene oxide edge. Theimmobilization of antibodied at the ITO/GO electrode was carried outthrough a stable acyl amino ester intermediate generated by EDC/NHS,which could condense antibodies densely and firmly on the electrode.The IL-6antigen was directly detected by as-prepared electrochemicalimmunosensor, and a linear relationship between the electron-transferresistance and the logarithmic value of IL-6concentration was found inthe range from1fg/mL to10ng/mL with the detection limit of1fg/mL,where the regression equation is Rct=261.15+13.72lg([IL-6]).(3) A label free impedance immunosensor was prepared based ongraphene oxide nanoparticles. Based on negative carboxyl group ofgraphene oxide edge, GO was directly deposited on ITO byelectrodeposition to build a simple and stable sensor base. Anti-CLBantibody was immobilized through a stable acyl amino ester intermediategenerated by EDC/NHS, and thus to improve the stability and sensitivityof immunosensor. The as-prepared sensor has showed a linearrelationship between the electron-transfer resistance and the logarithmicvalue of CLB concentration in the range from0.1ng/mL to1μg/mL withthe detection limit of0.1ng/mL, and showed good stability.