Review
Carbon-Nanotube Based Electrochemical Biosensors: A Review
Joseph Wang*
Department of Chemistry and Biochemistry, New Mexico State University Las Cruces, NM 88003, USA
*e-mail: joewang@nmsu.edu
Received: April 6, 2004
Final version: May 11, 2004
Abstract
This review addresses recent advances in carbon-nanotubes (CNT) based electrochemical biosensors. The unique
chemical and physical properties of CNT have paved the way to new and improved sensing devices, in general, and
electrochemical biosensors, in particular. CNT-based electrochemical transducers offer substantial improvements in
the performance of amperometric enzyme electrodes, immunosensors and nucleic-acid sensing devices. The greatly
enhanced electrochemical reactivity of hydrogen peroxide and NADH at CNT-modified electrodes makes these
nanomaterials extremely attractive for numerous oxidase- and dehydrogenase-based amperometric biosensors.
Aligned CNT “forests” can act as molecular wires to allow efficient electron transfer between the underlying
electrode and the redox centers of enzymes. Bioaffinity devices utilizing enzyme tags can greatly benefit from the
enhanced response of the biocatalytic-reaction product at the CNT transducer and from CNTamplification platforms
carrying multiple tags. Common designs of CNT-based biosensors are discussed, along with practical examples of such
devices. The successful realization of CNT-based biosensors requires proper control of their chemical and physical
properties, as well as their functionalization and surface immobilization.
Keywords: Carbon nanotubes, Biosensors, Glucose oxidase, Molecular wires, Nanomaterials, Enzyme electrodes,
DNA, Immunosensors
1. Introduction
Carbon nanotubes (CNT) have become the subject of
intense investigation since their discovery [1]. Such consid-
erable interest reflects the unique behavior of CNT, includ-
ing their remarkable electrical, chemical, mechanical and
structural properties. CNT can display metallic, semi-
conducting and superconducting electron transport, posse