Carbon nanotubes as electrode materials for the assembling of new electrochemical biosensors

We have investigated the electrochemical response of paste electrodes assembled using single-walled carbon nanotubes. The electrodes were prepared using 60% of Carbolex nanotubes mixed with 40% of mineral oil. Before use, the nanotube material was submitted to a sequence of chemical–physical purification steps to obtain samples consisting prevalently of single-walled carbon nanotubes (SWNT) and assure the reproducibility of measurements. In order to characterize these new modified electrodes, the electroanalytical response was evaluated for a number of molecules of biological interest performing cyclic voltammetry, differential pulse voltammetry and chronoamperometry experiments. Results highlighted the advantages of these new modified electrodes compared with those of conventional carbon paste electrodes: lower Ep, higher anodic current, better reversibility and sensitivity. The SWNT-modified electrodes were used for the investigation of very important neurotransmitters, as dopamine and DOPAC, biological molecules, as catechol and guanine, inorganic electroactive molecules, as ferricyanide, and also hydrogen peroxide and NADH which represent substrates, products and cofactors for more than 800 enzymes.