DNA is useful for many things, starting with that whole molecule-of-heredity thing and moving on to identifying murderers and rapists while exonerating the innocent. These are merely the tip of the iceberg, it turns out, when it comes to DNA’s talents: the double helix also makes an excellent origami material.
As scientists led by chemist Jørgen Kjems of Denmark’s Aarhus University report today in Nature, strands of DNA can be stitched together to form three-dimensional boxes measuring 42 by 36 by 36 nanometers. The key to making this work is that DNA is formed of molecules that recognize and bind with one another. Starting from this premise, Kjems and his colleagues wrote a computer program that determined which particular sequences of those molecules were needed to make a six-sided, hollow box—including an openable lid. The program spit out the answer: 220 snippets of DNA that will attach to the long piece of DNA from a virus called a bacteriophage.
All that was left for the scientists to do was buy the specified snippets and mix them with the long viral DNA. The snippets bent and turned each strand until it made a wall, and then attached the six walls into a box. In just a couple of hours the snippets had induced the self-assembly of billions of boxes. “It's amazing that it works,” Kjems told Nature. “It’s like taking your car apart, putting the nuts and bolts into a bag, shaking it, and the car builds itself.”
For their next clever move, the scientists attached a short stretch of DNA to one side of the box which was the chemical mate of another short stretch. When the second bit of DNA was added to the solution containing the boxes, it acted like a zipper tongue, unstitching the link between one wall and its neighbor so that the wall opened like a boxtop.
The zippable lid means that the DNA origami box might be used to transport drug molecules to a target in the body, releasing its contents only when the DNA un-zipper is added. Nature has a nice write-up in lay language here.