Caltech scientists control complex nucleation processes using DNA ori...(a map of the Western Hemisphere). Th...)

The structures designed by Rothemund, which could eventually be used in smaller, faster computers, were used as the seeds for the programmed self-assembly of DNA tiles described in the current paper.

In the work, the researchers designed several different versions of a DNA origami rectangle, 95 by 75 nanometers, which served as the seeds for the growth of different types of ribbon-like crystals of DNA. The seeds were combined in a test tube with other bits of DNA, called "tiles," heated, and then cooled slowly.

"As it cools, the first origami seed and the individual tiles form, as their component DNA molecules begin sticking to each other and folding into shape--but the tiles and origami don't stick to each other yet," Winfree explains.

"Then, at a lower temperature, the tiles start to stick to each other and to the origami. The critical concept here is that the DNA tiles will only form crystals if the process gets started by a seed, upon which they can grow," he says.

In this way, the DNA ribbons self-assemble themselves, but only into forms such as ribbons with particular widths and ribbons with stripe patterns prescribed by the original seed.

The work, Winfree says, "exhibits a degree of control over information-directed molecular self-assembly that is unprecedented in accuracy and complexity, which makes me feel that we are finally beginning to understand how to program information into molecules and have that information direct algorithmic processes."

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