Study On Potentiometric Biosensors Based On Carbon Nanotubes And Graphitization Ordered Mesoporous Carbon

Carbon nanotubes and graphitization ordered mesoporous carbon exhibit a great deal of characteristic ,such as high spicific surface, chemical stability, high mechanical strength and conductivity.They have broad application prospects in organic macromolecular adsorption separation, catalyst solid load and hydrogen storage etc. In recent years, the two kinds of nano-carbon materials have attracted much more attention in the application of biological sensors.A large number of documents report that electrochemical biosensor prepared with carbon nanotubes and graphitization ordered mesoporous carbon exhibit good sensitivity and electron transfer kinetics. However, functionalization and immobilization with carbon nanotubes and graphitization ordered mesoporous carbon on electrode surface is still the key problem in biological sensor research..In this paper, we investigated the applications of potential hydrogen peroxide sensor and potential immunosensors based on the carbon nanotubes and graphitization ordered mesoporous carbon . The major contents in this thesis include three sections as follows:(1) The development of a novel potentiometric hydrogen peroxide sensor based on carbon nanotubes.The carbon nanotubes (MWCNTs) and L-cysteine (L-cys) mixture is dipped onto the glassy carbon electrode(GCE)surface, then L-cysteine layer has been fabricated by electricity polymerization to form mosaic structure .The electrode has been prepared with EDC/NHS for coupling with horseradish peroxidase (HRP).Then the potential H₂O₂ sensor (HRP/poly-L-cys/MWCNTs/GCE) has been prepared . The preparation process of the modified electrode has been characterized by cyclic voltammetry and impedance spectroscopy . The effects of the pH value, temperature have been investigated. In optimization experiment condition, the slope of the standard curve of determining by H₂O₂ is 54.985. The sensor showed excellent response towards H₂O₂ range from 8.82×10^-8～3.53×10^-3mol/L and the detection limit of 3.0×10^-8 mol/L , r=0.9945.This sensor responsed to H₂O₂ more rapidly (<5min) and has good stability. The six same sensors have the same reproducibility.( 2 ) The development of a potentiometric immunosensor based on gold nanoparticles /poly-L-cysteine/carbon nanotubesThe glassy carbon electrode has been prepared by polymerizationtion with L-cysteine/carbon nanotubes composite by multi-walled carbon nanotubes as doping agent . Gold nanoparticles has been fabricated by electroplating onto the electrode surface, then fixed antibody, and the potential immunosensor (Ab/Nano-Au/poly-L-cys-MWCNTs/GCE) ) has been prepared . The preparation process of the modified electrodes has been characterized by cyclic voltammetry and impedance spectroscopy . The effects of concentration of polymerization solution, electrodeposition time of gold nanoparticles , fixing antibody time ,the pH value, temperature was investigated. In optimization experiment condition, the slope of the standard curve of determining antigen(Ag) is-6.338. The sensor shows excellent response towards Ag range from 2×10^-5～1×10³ng/mL and the detection limit of 1.54×10^-5 ng/mL , r=0.9965.This sensor responses to Ag more rapidly (<5min) and has good stability. The six same immunosensors have the same reproducibility and the immunosensor response work curre fell 16 percent after half month.(3)The development of a potentiometric immunosensor based on ordered mesoporous carbonThe electrode has been prepared with ordered mesoporous carbon coated gold nanoparticles (GNPs @ OMC). Then GNPs @ OMC with chitosan (Cs) solution has been fixed onto the electrode surface and fabricated by GNPs and OMC mixture by electrodeposition. And the potential immunosensors (Ab/GNPs@OMC/chito-GNPs-OMC/GCE) has been prepared. The preparation process of the modified electrodes is characterized by cyclic voltammetry and impedance spectroscopy. The effects of the pH value, temperature have been investigated. In optimization experiment condition, the slope of the standard curve of determining antigen(Ag) is -11287. The sensor showes excellent response towards Ag range from 2×10^-5～1×10³ ng/mL and the detection limit of 1.19×10^-5 ng/mL , r=0.9988.This sensor responses to Ag more rapidly (<5min) and has good stability. The six same immunosensor have the same reproducibility and the immunosensor response work curre fell 23 percent after half month .