June 21, 2006

DNA assembly line created

Ned Seeman and colleagues have put DNA robots to work by incorporating them into a self-assembling array. The composite device grabs various molecular chains, or "polymers," from a solution and fuses them together. By controlling the position of the nano-bots, the researchers can specify the arrangement of the finished polymer.

Seeman hopes this tiny assembly line can be expanded into nano-factories that would synthesize whole suites of polymers in parallel. The major challenge now is going from 2D arrays to 3D structures. The extra dimension would allow the fabrication of more elaborate molecules, as well as denser electronic circuits.

We have the ability to attach particles to DNA. Scientists can hitch functional materials like metals, semiconductors and insulators to specific DNA molecules, which can then carry their cargo to pre-specified positions. Already this technique has been used to make a simple transistor, as well as metallic wires.

There is a problem, however, in making more complicated components. To keep negatively-charged DNA stable, researchers add positive ions to their solutions. But these ions can interfere with the functional materials needed to build electronics.

A solution might be to use a DNA-like molecule that is uncharged and yet has the same code as DNA. There are about 1000 "flavors" of DNA derivatives, Seeman says, so one of these might do the trick.

These alternatives can be 10 times more expensive to make than regular DNA.