The Lion lies down with the Lamb

The recent report from P. Guo at Purdue that RNA can be used as the building block for nanostructures(original article in Nano Letters, subscription probably required; news report) has generated rare unanimity between the Drexlerian and the nanobusiness wings of the nanotechnology movement. Remarkably, the achievement has united the Tom and Jerry of the nanotechnology blog world, TNTlog, and the Center for Responsible Nanotechnology. Is this excitement warranted?

Very much so, in my view. The advantage of DNA as a nanotechnological building block (as demonstrated in Seeman’s work) is that the self-assembly process between base-pairs that creates the duplex, double helix structure, is very straightforward to understand and model. This means that the design process, in which one deduces what sequence of bases is required to produce a given 3d structure, is highly tractable. Proteins exhibit a much richer range of useful three dimensional structures, but rational design involves a solution of the protein folding problem, which still remains elusive. RNA offers a middle way; RNA self-assembly is still governed by straightward base pairing interactions involving four bases in two complementary pairs. But RNA, unlike DNA, can fold and form loops and hairpins, giving a much richer range of possible 3d structures. Thus, using RNA, we could get the best of both worlds – the richness of potential self-assembled structures of proteins, with the computational tractability of DNA.

We should remember that neither DNA nanotechnology nor RNA nanotechnology is likely to yield mass-market products any time soon – nucleic acids are delicate molecules that remain enormously expensive. But these lines of research are just the sort of avenue that publically funded nanoscience should be supporting – visionary stuff that can excite both the Drexlerian radicals and the pragmatic nano-businessmen.