Attaching a short DNA molecule to two metal electrodes, researchers in the Netherlands have found evidence that DNA acts as a semiconductor for electrical charge. The figure shows the electrodes as two gray cliffs on either side of a chasm. In the experiment, the electrodes were separated by just 8 nanometers (billionths of a meter). The DNA (the colorful rope across the canyon) was double-stranded with a length of 10.4 nanometers (billionths of a meter).
The research provides insights into a heavily debated question: Is DNA a conductor for electrical charge? The present work indicates that the DNA strands are semiconductors with large band gaps (typically around several volts), with a band gap indicating the amount of voltage required to boost an electron from the valence band (a state in which an electron is attached to a particular atom) to a conduction band (a state in which an electron can move freely in the material).
Therefore, by applying a sufficiently high voltage, one can greatly influence the flow of electrons in the DNA strand or any other wide bandgap semiconductor. Such work is leading to a new field called "DNA electronics," which may lead to intriguing new designs for biosensors and other devices
These experiments were performed by scientists at the DIMES institute of the Delft Institute of Technology in the Netherlands.
Figure copyright 2000 by the DIMES Institute, Delft Institute of Technology, the Netherlands. Journalists have permission to use these images if the source is acknowledged.
1) Danny Porath, Alexey Bezryadin, Simon de Vries and Cees Dekker; Direct measurements of electrical transport through DNA molecules, in the journal Nature, 10 February 2000.
2) A.Bezryadin, C. Dekker, and G. Schmid, Electrostatic trapping of single conducting nanoparticles between nanoelectrodes, in Applied Physics Letters, v. 71, p. 1273 (1997)