DNA drives photodetectors forward

17 Jun 2002

Italian scientists have developed a DNA-based rival to today's photodetectors.

Researchers at the universities of Leece and Bologna, Italy, have discovered that nucleoside deoxyguanosine, a compound that helps to encode genetic information in DNA, is an excellent alternative to conventional semiconductor materials in photodetectors.

For many years scientists have been racing to exploit biological materials that transport electronic charges and have developed molecular bioelectronic applications, such as hybrid protein/semiconductor electronic devices and DNA-based computers. A recent breakthrough comes from Ross Rinaldi and his colleagues, who have developed a metal-semiconductor-metal photodetector based on self-assembled layers of nucleoside deoxyguanosine.

The researchers created the basis of the photodetector by depositing two gold electrodes onto a silicon-based substrate. They then placed drops of a deoxyguanosine derivative and solvent solution between the junctions of the electrodes. They noticed that as the solvent evaporated, the deoxyguanosine atoms arranged themselves into streams of ribbons or aligned biological wires that formed a continuous film between the electrodes.

"Extensive transport and photocurrent experiments have revealed that the self-assembled deoxyguanosine films behave like wide-gap semiconductors," said Rinaldi in Applied Physics Letters 78 p3541-3543. He added that by optimizing atom self-assembly and illumination conditions, the device exhibited photodetection behavior equal to today's conventional, fast photodetectors.

The team now hopes to extend the self-organization length of the deoxyguanosine ribbons so that they can deposit the solution onto the photodetector substrate using a conventional ink-jet printer, and ease production. "We envisage a new generation of biomolecular planar devices, written by an ink-jet printer onto standard lithographically defined patterns," said Rinaldi.