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IBM twists DNA for future chip fab tech

Organic armature for nanotubues, anyone?

Read the release and you'd think IBM has discovered the Holy Grail of chip making: a way to "pack more power and speed" into microprocessors, while "making them more energy efficient and less expensive to manufacture".

One day, maybe. For now, though, the concept of using DNA to create shapes onto which chip makers can then bind "carbon nanotubes, silicon nanowires or quantum dots" to create processors remains a 'could' rather than a 'can'.

But the IBM breakthrough is a step in that direction, providing a basis for techniques by which such chips may be fabricated rather an innovation in the design of the chips themselves.

What a team from IBM and the California Institute of Technology, led by Paul W K Rothemund, have done is use established chip making techniques, specifically electron-beam lithography and dry oxidative etching, to create anchor points onto which sculpted strands of DNA can then bind precisely and accurately.

IBM DNA chip tech

DNA binding sites, yesterday

The DNA sculptures are created in solution using essentially the same methodology that DNA use to replicate itself within living cells. The molecule's base pairs will only attach to their specific partners - cytosine to guanine, for instance - allowing one strand of the double-helix to provide a template for the second strand.

By sequencing their own run of base pairs, attached to a single strand of viral DNA, and applying a mixture of different short synthetic oligonucleotide strands as mounting points, the team created self-assembling DNA molecules that were folded - a process dubbed by some wag 'DNA Origami' - into specific shapes ready to fit into the lithographed anchor points.

The team said that DNA nanostructures such as squares, triangles and stars can be prepared with dimensions of 100-150nm on an edge and a thickness of the width of the DNA double helix.

The team were able to demonstrate that the folded DNA molecules generally attach to the correct points and with the correct orientation - the technique works reasonably accurately, in other words.

Creating DNA shapes isn't new, but getting them to bid to a silicon substrate in an orderly, controlled way has not proved successful before. Central to the breakthrough were finding the right material on which the DNA shapes would bind and the right conditions to encourage binding and accurate orientation. The upshot is a DNA scaffold onto which active future chip components can be assembled. ®

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