Surface Functionalized Carbon Nanotubes And Their Bioelectrochemical Properties

Carbon nanotubes (CNTs) have been studied extensively since its discovery in 1991. With its unique one-dimensional tubular structure, high aspect ratio and physical chemistry properties, CNTs attracted more and more research interests in various fields, especially in the field of bioelectrochemistry due to their wonder structure and electrical properties.Unfortunately, CNTs aggregate easily due to high surface free energy, which limits their applications remarkably. In order to improve the dispersion and biocompatibility of CNTs, the noncovalence functionalization of CNTs surface with nature biomedical macromolecule-chitosan was carried out in this paper. The functionalized CNTs could form stable uniformly dispersed black water solution, and form uniform three-dimensional reticular structure on the solid substrate and increase the surface area of substrate. The CNTs-Chitosan composite film could provide a favourable micro-environment for the hemoglobin(Hb), and the Hb entrapped in the composite film had a similar structure to the native of Hb and retained its near-native second conformations. It was found that the direct electron transfer between Hb and CNTs-Chitosan modified electrode took place, with the electron transfer rate constant of 167 s^-1. The Hb adsorbed onto the composite film was found to possess good bioelectrochemical catalytic activities toward the reductions of O₂ and H₂O₂, providing a new promising platform for the development of biosensors.In this paper, we described a new strategy for layer-by-layer(LbL) assembling of CNTs treated with mixed acid. The layer-by-layer self-assembly of the negatively charged CNTs with polycation chitosan has been constructed onto indium tin oxide(ITO)-coated glass plate through an alternative adsorption of oppositely charge, and the electrocatalytic activity of CNTs toward Ascorbic acid(AA) had been studied.. Scanning electron microscopy(SEM), Cyclic voltammetry(CV) and UV-vis-NIR spectroscopy studies indicated the CNTs composite film possessed the advantages of the uniform growth of the film and the controllable amount of CNTs. The electrocatalytic behavior of multilayer modified electrodes with different numbers of the bilayer to AA reflected that AA had lower oxidation overpotential along with the growth of multilayer film onto the ITO. The peak current of AA increased linearly with the square root of scan rate, indicating that the electrochemical behavior was a diffusion-controlled process on the surface of multilayer self-assembling film. This work will establish the foundation for the determination of AA using CNTs.