DNA is one of the most promising materials for the construction of arbitrarily tailored 3D nanostructures. Researchers from Arizona State University, Tempe, and the Scripps Research Institute, La Jolla, have found a way to trigger self-assembly of DNA tubules [Sharma et al., Science (2009) 323, 112]. “A key prospect of structural DNA nanotechnology is to be able to design and construct nanoscale geometrical shapes in a programmable way. So far the field has demonstrated that we can make 1D, 2D, 3D structures of different shapes. Diatoms, foraminifers, viral capsids etc. are wonderful examples of how self-assembly works in nature,” says Hao Yan, the corresponding author. To progress from lower dimensional to 3D structures, Yan and colleagues have attached gold nanoparticles (AuNPs) via a thiol group to DNA double helices. This combination proved convenient as the DNA-gold conjugates are stable and, in addition, provide effective image enhancement for electron microscopy.
When such modified helices arrange themselves parallel to each other, steric and electrostatic repulsions between neighbouring AuNPs cause curling of the molecular arrangement, which leads to the formation of various tube structures, with the particles on the outside. Depending on the size of the AuNPs and the offset of the parallel strands, a variety of structures are obtained: without any offset, tubes displaying rings of AuNPs are formed, otherwise single, double spiralled tubes, or even double-walled spiral tubes, can be assembled. The manufacturing of tailored DNA architecture mounted with gold or other nanoparticles seems a highly promising lead towards several nanotechnological applications. Nanoelectronics or –photonics come to mind, but Yan can imagine more spectacular devices. “Inductors are but one example that can be made from a spiralling AuNP with a magnetic core,” says Yan. “It would be even more exciting if a designer DNA tube could be used to channel electrical communication through neuron cells. The tube could serve as an interconnect for nanoelectronic devices.”