DNA origami

Nanoscale folding of DNA, also known as DNA origami, was pioneered by Paul Rothemund at California Institute of Technology. The process allows researchers to create arbitrary two-dimensional shapes at the nanoscale using DNA. Novel designs have included the smiley face and a coarse map of North America. DNA origami was the cover story of Nature on March 15, 2006.

Rothemund's process involves the folding of a single long strand of viral DNA aided by several smaller "staple" strands. These strands serve to provide structural support for the larger design. To be used in DNA origami, images must be able to be drawn using a single long DNA molecule. The design is then fed into a computer program, which calculates the placement of individual staple strands. Each staple binds to a specific region of the DNA template, conferring the property of self-asssmbly to the process.

The output of the process is an image composed of pixels roughly 6nm in size. Designs are directly observable via atomic force microscopy.

In his paper, Rothemund conjectures that it may be possible to extend his raster-filling layer process to three dimensions.