DNA Semiconductors?

Attaching a short DNA molecule to two metal electrodes, researchers have found evidence that DNA acts as a semiconductor for an electrical charge (D. Porath, A. Bezryadin, S. de Vries and C. Dekker, "Direct measurements of electrical transport through DNA molecules," Nature 403, 635—638 (2000)). The figure above 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 10.4 nm-long DNA (the colorful rope across the canyon) was double-stranded.

This research provides insights into a heavily debated question: "Is DNA a conductor for electrical charge?" This 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 can not be accelerated) to a conduction band (a state in which an electron can move freely in the material). Therefore, by applying a sufficiently high voltage, the flow of electrons in the DNA strand or any other wide bandgap semiconductor may be greatly influenced. Such work is leading to a new field called "DNA electronics," which may lead to intriguing new designs for biosensors and other devices.

For further information, contact Professor Bezryadin.

Figure copyright 2000 by the DIMES Institute, Delft Institute of Technology, the Netherlands, and used with permission.

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