DNA, the excellent molecule for duplication and storage of genetic information in biology, has recently been shown to be very useful as a structural material for construction of electrical nanodevices, biological sensors and molecular computers with nanoscale feature resolution. Properly designed synthetic DNA can be thought of as a programmable glue which, via specific hybridization of complementary sequences, will reliably self-organize to form desired structures. The significance of patterned DNA nanostructures lies in their application as scaffolds or templates for organizing and positioning other materials.

We present the design, construction, and characterization of a novel DNA tile (so called as 4x4) and its self-assembled lattice forms. The novelty of this structure includes a square aspect ratio with helix stacking and sticky-end connections in four directions (north, south, east, and west) within the lattice plane. Self-assembly of 4x4 tiles results in two distinct lattice morphologies: long (>10 mm) uniform nanoribbons (~60 nm wide) and flat two-dimensional nanogrids which display periodic square cavities. Control of the relative proportions of the two lattice morphologies has been achieved with only slight reprogramming of the tile spacing and sticky-end associations.

The 4x4 nanoribbon provides an excellent scaffold for production of uniform width nanowires via DNA metallization with silver. We have, for the first time, produced highly conductive nanowires on self-assembled DNA tiling structures. Metallization and conductivity measurements of metallized 4x4 ribbon lattices. a, SEM image of non-metallized 4x4 DNA nanoribbons (scale bar: 500 nm). b, SEM image of silver-seeded silver nanoribbon, (scale bar: 500 nm). Note the change in the signal contrast between a) and b). The samples were deposited on SiO₂ surface. c, SEM image of the actual device (scale bar: 2 um). Inset : current-voltage curve of the silver-seeded silver 4x4 nanoribbon.

Self-assembly of protein arrays templated by 4x4 DNA nanogrids. a, schematic drawing of the DNA nanogrids scaffolded assembly of streptavidin. Left: The DNA nanogrids, a biotin group labeled as a red letter B are incorporated into one of the loops at the center of each tile. Right: Binding of streptavidin (represented by a blue tetramer) to biotin group will lead to protein nanoarrays on DNA lattices. b, an AFM image of the self-assembled protein arrays, scale bars are shown below the image.