Smaller DNA tiles attach to the DNA seed and the structure snowballs in size to make a structure up to 100 times bigger than the original segment.
When the two unwound types of DNA undergo cycles of temperature variation between 40 and 90 °C, they fold into seeds and tiles, and then begin to accrete together into the much larger structure. The “growth” process is directed by the sequence of information written into the seed’s DNA.
The team has designed the tile DNA sequences to “proof read” their own work and spontaneously reject most erroneous assembly steps.
Although the team has so far used the technique to build simple pipes (see image, top right), much more is possible, Winfree says. “Metaphorically, this is similar to how genetic programs within cells direct the growth of an organism.”
Winfree and Rothemund speculate that the technique could provide a way to assemble molecular components into useful structures such as tiny electric circuits. It is also possible to use the self-assembling DNA structures to perform computational tasks, adds Winfree.
“It is very powerful for information processing,” he says. “It’s what’s known as a Universal Turing Machine, which means it can carry out any information processing task.”