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February 4th, 2008

DNA cages change size on demand

Abstract:
UK and German scientists have designed dynamic DNA cages which expand or contract on demand - and could be used to deliver drugs, or be the moving parts of nanomachines.

Researchers working with DNA have coaxed the strands into various impressive structures over the last two decades - including cubes, prisms, tetrahedra, and other exotic polyhedra. But these have usually been rigid and static: each edge consisting of a short double-stranded DNA segment.

But now, researchers based at the Universities of Oxford and Bielefield have built tetrahedra with one unusual edge that includes a single-stranded segment of DNA in its middle section[1]. This segment normally bunches up into a hairpin structure, but it straightens out - thus lengthening the entire edge - when it binds to a complementary single-stranded DNA segment.

By 'fuelling' the tetrahedra with the requisite complementary DNA segment, the researchers were able to expand the cage. Conversely, when they added 'anti-fuel' strands, they stuck to 'fuelling' DNA, pulling it away from the edge of the cage and making it contract again. The team also made a tetrahedron with two variable-length edges, which could independently expand or contract - dramatically changing the shape of the cage.

Source:
rsc.org

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