Low-potential stable NADH detection at carbon-nanotube-modified glassy carbon electrodes

Carbon-nanotube (CNT)-modified glassy carbon electrodes exhibiting strong and stable electrocatalytic response toward NADH are described. A substantial (490 mV) decrease in the overvoltage of the NADH oxidation reaction (compared to ordinary carbon electrodes) is observed using single-wall and multi-wall carbon-nanotube coatings, with oxidation starting at ca. -0.05 V (vs. Ag/AgCl; pH 7.4). Furthermore, the NADH amperometric response of the coated electrodes is extremely stable, with 96% and 90% of the initial activity remaining after 60 min stirring of 2 x 10(-4) and 5 x 10(-3) M NADH solutions, respectively (compared to 20% and 14% at the bare surface). The CNT-coated electrodes thus allow highly sensitive, low-potential, stable amperometric sensing. Such ability of carbon nanotubes to promote the NADH electron-transfer reaction suggests great promise for dehydrogenase-based amperometric biosensors. (C) 2002 Elsevier Science B.V. All rights reserved.