I've talked recently about some of the cool stuff you can do with DNA. Here's one more: DNA can be used to sort single-walled carbon nanotubes.
Carbon nanotubes come in a variety of different styles. Imagine cutting a narrow strip of plaid cloth and wrapping it around a pencil. Depending on the angle of the wrap, the stripes would line up - or not - at various angles. A carbon nanotube can be thought of as a thin strip of graphite-like carbon, in which the atoms are lined up in regular rows, coiled up to form a tube.
Depending on the angle of the carbon rows - the so-called chirality of the tube - it can be a metal, insulator, or semiconductor. This makes it very interesting for computer applications. The trouble is that it's hard to synthesize just one kind of tube, and until now, it's been hard to separate out one kind from a mixture.
As reported in Nature, a group of researchers has searched among a massive number of DNA sequences to find sequences that will fold just right to wrap around tubes of only one particular chirality. This allows the wrapped tubes to be separated from the mixture. The DNA folds up into zig-zag sheets, which then wrap around the tubes that have just the right chirality.
This isn't the first time DNA has been attached to nanotubes, but it's cool that it is attaching to a single kind. And it sounds like the zone of attachment is large enough to form a reasonably strong connection. Although the researchers are mainly interested in electronic applications (at least, judging from the abstract of their paper), it may be that interesting nanomechanical applications will also be enabled by this work.
(Hat tip to Eric Drexler's Metamodern blog.)
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