DNA-based computers are one step closer to full realisation following the creation of simple DNA machines that can switch between two shapes with only a single trigger.
The switching ability, which is fully reversible, means that information is being relayed at a molecular level – transferred between DNA structural units – in a manner than is both self-sustaining and controllable.
Lead researcher Yonggang Ke of the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech, US, says the micromachines can be used to either relay specific pieces of information through a DNA-constructed system, or to amplify a signal emanating from another part of it.
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“In the field of DNA-based computing, the DNA contains the information, but the molecules are floating around in solution,” Ke says.
“What’s new here is that we are linking the parts together in a physical machine.”
Ke and colleagues constructed two different nanomachines, each comprising a number of artificial DNA double helixes stacked on each other, in two orientations, providing strength and stability.
The completed design looks rather like an accordion, or a foldable trellis.
One extra strand at the edge of each machine is attached, and functions as a trigger. When activated it compels the first DNA strand of the machine array to contract (or expand, depending on its initial state). This in turn transfers energy to the next strand, causing it to move in the same way, and so on, a little like dominoes falling.
The machines, fully built, are just a few hundred nanometres long – slightly smaller than an influenza virus. To see them, Ke and colleagues used a powerful imaging technique known as atomic force microscopy.
Constructing machines on a nanometric scale would seem to require some impossibly fine hand-eye coordination on the part of the molecular engineers, but the compulsion of DNA’s chemical structures to automatically bond means that, in solution, they seek out the complimentary strands of their neighbours, making construction a guided, rather than mechanical, process.
Although the machines built by Ke and his colleagues are very simple, they provide a powerful pathway towards construction of more complex structures. In research published in the journal Science, the team include blueprints for rectangles, cubes and tubes built by the same process.