Folding DNA into the shape of a tiny bunny rabbit is now easier than ever, according to a study published in Nature today. Folding DNA isn’t new — it’s known as DNA origami — but automating the process is. Thanks to a set of computer algorithms, researchers have developed a way to streamline the design phase that comes before the DNA assembly — a substantial step toward 3D printing at the nanoscale.
If DNA origami were a lego project, "base pairs" would be the bricks
If DNA origami were a lego project, "base pairs" — the biological units that make up the DNA double helix — would be the bricks. These units follow strict pairing rules, such that base "A" can only combine with base "T" to form a unit, whereas "C" can only link itself to "G." And when they're combined, base pairs form very predictable shapes — ones that scientists have begun to harness. This is the field of DNA nanotechnology, a field that aims to design and manufacture tiny structures made of DNA that can then be used to deliver drugs, or even to make electronics. Currently, DNA manipulation is time-consuming and costly; the new method promises to make it simpler and cheaper.
That's why today's study matters. It's a solid step toward a fully automated construction method — one that wouldn't be unlike your friendly neighborhood 3D printer, except with DNA.
The design process, from start to finish. (Erik Benson and Björn Högberg)
In the study, the researchers used design software to draw complex shapes in 3D, such as a bottle, a bunny, and a waving humanoid. Then, they used their specially tailored computer algorithms to plan the DNA scaffolding that would form the 3D object. So when the researchers ran their algorithms on a 3D bunny, for example, the computer spat out a list of short DNA sequences that — when combined under the right temperature conditions — would automatically assemble to form the rabbit in question.
Algorithms map out the DNA sequences that will make a bunny
The next step was to order the building materials — so the researchers sent their computer-generated list to a company called Integrated DNA Technologies, which specializes in manufacturing DNA from viruses. They got their supplies: small tests tubes filled with close to 200 short strands of DNA. Putting these manufactured DNA strands through warming and cooling procedures prompted them to automatically assemble, following the exact path the algorithm had determined.
By the time the researchers were done, they had tiny nanoscale, rabbit-shaped DNA on their hands. "All the DNA strands find their right place in the structure," says Björn Högberg, a chemical engineer at the Karolinska Institute in Sweden and a co-author of the study.
A ball, a nicked torus, a rod, a helix, a waving stickman, a bottle, and a version of the Stanford bunny. (Högberg et al, 2015)
"[This] has not been done before, it is novel and surprising," says Thorsten Schmidt, a chemist at the Dresden University of Technology who didn't work on the study. "In fact, we have a very related study under review at the moment and the only bad aspect of Björn Högberg’s study is that they were faster than us."
"The only bad aspect of Björn Högberg’s study is that they were faster than us."
The bunny, while cute, wasn’t the point of the study. Rather, it’s a demonstration that scientists can automatically generate a DNA sequence to form a complex shape — the closest thing to 3D printing on a very tiny scale. "It’s almost a one-click procedure," Högberg says. And if scientists can fully automate the process, they’ll have a real DNA printer at their disposal — one that could, among other things, make drugs easier to deliver to the right places in the body.
Actually, there are a lot of ideas about how these techniques could be used. In addition to drug delivery, researchers are working on coating the DNA structures with non-biological materials, like gold, that react when the structure comes in contact with light.
Drug delivery methods and gold-covered DNA
But at this point, the bunny and the bottle don't do all that much. "We're not really concerned with the genetic information," Högberg says. "We're using DNA purely as a construction material."
Now that the study has been published, the researchers want to find a way to make their own construction materials. That may mean using natural DNA — taken from a plant or bacteria that they cultivate themselves — instead of synthetic DNA, Högberg says.
"We're getting very good at making structures at the nanoscale," Högberg says. Researchers just need to find a way to make lots tiny DNA bunnies cheaply — and all at once.