Carbon-nanotube-modified electrodes for amplified enzyme-based electrical detection of DNA hybridization

Carbon-nanotube-modified glassy carbon (CNT/GC) transducers have been developed for enhancing the sensitivity and stability of enzyme-based electrochemical bioassays of DNA hybridization. The amplified signal reflects the interfacial accumulation of phenolic products of the alkaline-phosphatase tracer onto the CNT layer. In particular, chromopotentiometric measurements (following short accumulation periods) offer a substantial enhancement of the response of enzymatically liberated alpha-naphthol. The CNT modifier also leads to a dramatic improvement in the stability of the amperometric response of alpha-naphthol. These advantages of CNT/GC electrodes are illustrated from comparison to unmodified glassy carbon electrodes. Factors influencing the adsorptive accumulation of alpha-naphthol, and the overall performance of the new DNA assay, are assessed and optimized. The attractive performance characteristics of the new multi-amplification electrochemical detection of DNA hybridization are reported in connection to the detection of nucleic acid sequences related to the breast cancer BRCA1 gene. (C) 2004 Elsevier B.V. All rights reserved.