DNA "origami" is opening the door to the smallest structures ever madeby Philip Ball / June 19, 2013 / Leave a comment
Clockwise from top left, Seeman’s DNA cube; Rothemund’s smiley face; a map of the world; DNA cubes with opening lids. Clockwise from top left © Courtesy of Nadrian C. Seeman, New York University; © Paul Rothemund; © California Institute of Technology; © Jørgen Kjems, Lundbeck Nanomedicine Center (Luna)
James Watson and Francis Crick’s paper in Nature on the structure of DNA, published 60 years ago, anticipated the entire basis of modern genetics. The structure they postulated is both iconic and beautiful: a double helix, composed of two entwined strands of conjoined molecular material, each consisting of a sequence of genetic building blocks. The two strands are bound to one another by chemical bonds and, as Watson and Crick realised, for the binding to be secure there must be a perfect match between the sequence of building blocks on each strand. Any errors in this matching make the double helix apt to separate again into its component strands. DNA, packaged in an organism’s genome, carries information essential to the organism’s functioning and replication. But the details are complex and still being unravelled, and this picture of a molecule whose chemical structure encodes instructions for zipping up only with the right partner has been seized by the field of nanotechnology—engineering matter at the scale of nanometres (millionths of a millimetre), the dimensions of molecules.
Here it becomes immensely hard, if not impossible, to arrange and manipulate objects using the techniques that work at larger scales. However, the ability to programme assembly instructions into strands of DNA offers a powerful new alternative, raising the possibility of tiny structures and machines that “make themselves” from their molecular-scale components.
Research in nanotechnology has been propelled partly by the race to miniaturise transistors and other components of microelectronic circuitry. Computer processors and memories are now so small that conventional methods of carving and shaping materials are stretched to the limits of their finesse.
DNA nanotechnology offers one way for scientists to replace such methods of production. Rather than taking a lump of material and sculpting it into the desired shape, nanotechnologists can instead use the selective bonding characteristics of DNA to assemble objects at the molecular level—and perhaps even to dictate their movements.
For example, chemists have now created molecular machines from bespoke pieces of DNA that can move along surfaces. They have made molecular-sized cubes and meshes, and have…