ABSTRACT
Carbon nanotubes (CNTs) have attracted a great deal of interest due to the unique combination of their one-dimensional molecular symmetries and physicochemical properties. In order to meet specific requirements demanded for particular applications, chemical modification of CNTs is essential. As electrode materials, CNTs possess many advantages, including their excellent electrical property, high chemical stability, strong mechanical strength, and large surface area. Large surface area and high conductivity of CNTs make the CNT-based sensors generally bear a large non-faradaic current, rendering difficulties in trace amount voltammetric measurements. The use of ordered CNTs as biosensing electrodes should provide additional advantages than the aforementioned electrodes based on the nonaligned, randomly entangled CNTs. A typical impedance spectrum presented in the form of the Nyquist plot includes a semicircle portion at higher frequencies corresponding to the electron-transfer-limited process and a linear part at a lower frequency range associated with the diffusion-limited process.
