Biofuel cells that utilize enzymes are attractive alternatives to metal catalyst-based cells because they are environmentally friendly, renewable and operate well at room temperature. Glucose oxidase (GOD)/laccase based biofuel cells have been evaluated to determine if they are useful power supplies that can be implanted in vivo. However, the usefulness of GOD/laccase systems is limited because they produce low level of electrical power. The effects of DNA-wrapped single-wall carbon nanotubes (SWNTs) on the electrical properties of a fuel cell are evaluated under ambient conditions in an attempt to increase the electrical power of an enzyme-based biofuel cell (EFC). The anode (GOD) and cathode (laccase) system in the EFC is composed of gold electrodes that are modified with DNA-wrapped SWNTs. Glucose (for anode) and O-2 (for cathode) are used as the substrates. The anodic electrical properties increase significantly with a bioelectrode that contains DNA-wrapped SWNTs as an electron-transfer mediator. Furthermore, the modified bioelectrode results in increased activities and stabilities of GOD and laccase, which enhance power production (442 mu W cm(-2) at 0.46V) compared with a basic EFC. (C) 2009 Elsevier B.V. All rights reserved.