Application Of Carbon Nanotubes And Gold Modified Electrode In Bioelectroanalysis

The mediator on the eletrode surface could control the electrochemical reaction rate of target substance, as a result, it has selective electrocatalytic effect. Because of their structural characteristics and excellent electrocatalytic properties, carbon nanotubes and gold have been the focus of CMEs. We used carbon nanotubes and gold as mediators and the main works in this thesis include:1. A multi-wall carbon nanotubes (MWCNTs) composite with Nafion was modified on a glass carbon electrode. The surface morphology of the Nafion/MWCNTs composite film was characterized by atomic force microscopy (AFM). The modified electrode was then used as a voltammetric sensor in detecting 2,4,6-triaminopyrimidine(TAP), and the electrochemical behavior of TAP at this sensor was investigated in detail. The results indicated that the Nafion/MWCNTs modified electrode exhibited efficient electrocatalytic oxidation for TAP with relatively high sensitivity, stability and lifetime. Under the optimized condition using linear sweep voltammetry (LSV), the Nafion/MWCNTs modified electrode exhibited a linear voltammetric response for TAP in the concentration range of 2.0×10-7 to 3.6×10-5 mol L-1, with a detection limit of 5.0×10-8 mol L-'. The electrode was applied to detect TAP added to human blood serum, with an average recovery value of 101.3%.2. In order to solve the insolubility of CNTs, Single-walled carbon nanotubes (SWCNTs) were effectively dispersed and functionalized by wrapping with single-stranded DNA (ssDNA). The SWCNTs solution was characterized by Transmission Electron Microscopy (TEM). The solution was fabricated into a working electrode, The Nafion/DNA/MWCNTs composite film was characterized by electrochemical impedance spectroscopy (EIS) and voltammetry, and the electrochemical behavior of baicalein at this sensor was investigated in pH 3.29 Britton-Robinson buffer solutions by cyclic voltammetry (CV). Compared with bare glassy carbon electrode, the experimental results suggested that the modified electrode exhibited an electrocatalytic activity toward the redox of baicalein. Under the optimum experimental conditions, the modified electrode shows a linear voltammetric response in the range of 8.0×10-8～1.0×10-5 mol L-1. The detection limit for baicalein was calculated at a value of 2.0×10-8 mol L-1. The proposed method was also applied to determine baicalein in human blood serum samples. In addition, the fabricated electrode exhibited a distinct advantage of good reproducibility and good stability.3. In this work, we prepared a novel gold film modified platinum electrode with pulse plating method. EIS and some other electrochemistry methods were used to investigate the modified electrode's and electrochemical functions. The electrochemical behaviors and electrocatalysis of ketamine are investigated systemly. The results indicated that this kind of modified electrode had an obvious excellent electrochemical catalytic effect on Ketamine.Meanwhile, we studied the factors of pulse plating which can affect the modified electrode's electrocatalysis properties. Under the best optimizations, the electrochemical behaviors of Ketamine was performed in the buffer solution composed of BR(pH=1.81), the single oxidation peak of Ketamine was found at 1.16V,and we established an electrochemical methods to detect the ketamine and the range of the linearity was 7.3×10-6～3.6×10-3 mol L-1 the detection limit was 1.8×10-6 mol/L。The modified electrode showed good sensitivity, selectivity, stability and less interference.