Label-free nucleic acid biosensors using carbon nanotubes

Single-wall carbon nanotubes (CNTs) belong to a unique class of one-dimensional nanostrcutures due to their all-carbon structure coupled with their very high aspect (at least 1000:1) and surface-tovolume ratios. Unlike bulk wires, charge variations on the surface of CNTs cause distinct changes in their electronic properties. These aspects make CNTs promising components for electrical biosensors. [1] Electrical biodetection methods are continuously being sought for, in order to miniaturize device footprint to obtain sensors in a compact and portable format. Furthermore, bulky optical reading instruments that are required with current technologies can be avoided. Here we demonstrate a highly sensitive biosensor for the detection of nucleic acids. It is based on the use of CNT field-effect devices and is capable of detecting as low as 2000 copies of deoxyribonucleic acid (DNA) molecules in a 30 microlitre sample droplet.