Investigation of the Mechanism of Adsorption of beta-Nicotinamide Adenine Dinucleotide on Single-Walled Carbon Nanotubes

We address in this manuscript the important issue of the stability of single-walled carbon nanotube (SWCNT)-based electrodes upon oxidation of NADH to NAD(+). NADH and NAD(+) play a key role in the development of electrochemical enzyme-based biofuel cells and biosensors. However, most of the electrode, materials exhibit strong surface passivation when oxidation of NADH to NAD(+) occurs. SWCNT-based electrodes are not affected by such a passivation effect. In the present work, we address the fundamental question, "why are the single-walled carbon nanotube electrodes prone to passivation?" using electrochemical methods and first-principles molecular dynamics simulations. We found that this is due to the wide exposed surface of SWCNT-based electrodes rather than other "inherent" properties of SWCNTs, such as the electrocatalytic effect and high curvature.