Wednesday, January 13, 1999 Published at 19:06 GMT
New twist for nanotechnology
Professor Ned Seeman has created many self-assembling molecular structures
It's one small step for DNA, one vast leap for nanotechnology.
Scientists in New York have created a nanometre-sized moving arm from synthetic DNA. This kind of mechanical device, which operates on an molecular scale, is seen as the precursor for nano-robots which will manufacture or repair molecules, possibly within the human body.
"The ultimate uses of this new moecule will be in the analytical, in the laboratory, and also techological. Ultimately we will be able to make small nanomachines that can do molecular manufacturing and then step up to nanorobots."
10 year timescale
The new device, reported in Nature, has two rigid DNA arms linked by a special piece of DNA. This helix in this special piece winds in the usual direction, right-handed.
However, when a cobalt compound is put into solution and comes close to the linking DNA, the interaction of electrical charges causes the linking piece to flip into a helix wound in the opposite direction.
This flip means that the two arms connected move away from each other by up to 6 nanometres, a significant distance in the nano-world.
With such a tiny machine, the researchers had to devise a way of seeing whether it had actually moved after the cobalt hexamine is added. At each end of the two DNA arms they placed fluorescent dye molecules.
When the DNA link is untwisted the dyes sit next to each other and flourescent light is given off. When the link twists and the arms move the dyes are separated making the solution go dark.