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Last Updated:  Tuesday, 1 April, 2003, 15:27 GMT 16:27 UK
'Nanowire' breakthrough hailed
Microscopic wires which could help form the miniature technology of the future have been constructed using the basic building blocks of living things.

Printed circuit board
Scientists hope that chips can be made much smaller than this
The human body is one of the ultimate examples of a self-assembly machine, with every part a complex arrangement of intricately folded proteins.

Scientists are only just beginning to understand how this is achieved.

Experts in nanotechnology, who are trying to come up with ways of wiring the next generation of microscopic electronic circuits, believe that protein folding could hold the key to progress.

Research teams from universities in the US and Germany believe that certain arrangements of protein fibres could be produced reliably over and over again in an industrial setting.

These could be "coated" in gold or silver, potentially producing wires thousands of times smaller in diameter than the tiniest available currently.

Prion protein

The latest research, published in the Proceedings of the National Academy of Sciences, focused on a "prion" protein produced by a type of yeast.

In humans, it is a corruption of the prion protein which is blamed for vCJD.

The potential for such bio-inspired nanoscale engineering is immense as this is the stuff upon which the whole of the living world is built
Dr Dek Woolfson, University of Sussex
The prion protein was chosen for this research because of its natural toughness. It is far more difficult to break down than many other proteins.

The prion protein does not conduct electricity naturally, so this version was genetically modified so its surface layer would retain a thin layer of gold.

The resulting fibres were approximately 100 nanometres in diameter. One nanometre is a billionth of a metre, and, in comparison, a human hair is approximately 100,000 nanometres.

Little resistance

The researchers, led by Professor Susan Linquist, passed a tiny current through their nanowires, and measured their electrical resistance.

This is key to the success of any nanowire, as too high a resistance would lead to the wire heating up with the current, and probably being destroyed.

The prion-based nanowire gave a steady reading of approximately 80 ohms. The best achieved with other prospective nanowires, for instance protein microtubules, is about 1,000 times that figure.

The researchers wrote: "Our work provides a mechanism for generating robust nanowires that meet the needs of industrial processes.

They suggested that templates could be used to encourage the proteins to grow and form complex circuitry.

Professor Lindquist said: "Most of the people working on nanocircuits are trying to build them using 'top-down' fabrication techniques.

"We thought we'd try a 'bottom-up' approach, and let molecular self-assembly do the hard work for us."

Major applications

British experts were impressed by the results.

Dr Dek Woolfson, from the University of Sussex, is also working to manipulate the self-assembly of protein fibres with both nanotechnology and tissue-engineering applications in mind.

He told BBC News Online: "What Professor Lindquist's group has achieved is very exciting - making nanoscale wires that conduct with low resistance has great potential for creating tiny devices.

"In general, the potential for such bio-inspired nanoscale engineering is immense as this is the stuff upon which the whole of the living world is built."

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