Fabrication, Characterization And Application Of Carbon Nanotube Electrode In Bioelectrochemistry

This thesis studied the fabrication, characterization and applications of multi-walled carbon nanotube (MWNT) modified electrode. Extensive studies were made on the applications of the electrode to direct electron transfer reaction of myoglobin (Mb), ferredoxin (SoFd). The electrochemical biosensor based on alcohol dehydrogenase was fabrication and its performances were also characterized. The main research works are expressed as follows:1. Mb was immobilized on the surface of MWNT and the direct electron transfer reaction was studied. Cyclic voltammetric results showed a pair of well-defined redox peaks, which corresponded to the direct electron transfer of Mb, .with the formal potential (E^0') of -0.343 ± 0.001 V (vs. SCE) in the phosphate buffer solution (pH 7.0). The electrochemical parameters such as apparent heterogeneous electron transfer rate constant (k_s) and the value of formal potential (E^0') were estimated. The dependence of E^0' on solution pH indicated that the direct electron transfer reaction of Mb is coupled with proton transfer. The experimental results also demonstrated that the immobilized Mb retained its bioelectrocatalytic activity to the reduction of H₂O₂ and O₂.2. Spinacia oleracea ferredoxin (SoFd), which was immobilize on the surface of the carbon nanotube modified glassy carbon electrode, could undergo effective and stable direct electron transfer reaction. The results of Fourier transform infrared (FTIR) spectra indicated that the procedures of immobilization SoFd on the surface of MWNT did not alter the integrate structure of SoFd or damage SoFd leading to a denatured state and SoFd retains the essential feature of its secondary structure on the surface of MWNT. The cyclic voltammetric results indicated that the SoFd-MWNT/GC electrode exhibits a pair of well-defined and nearly symmetrical...