Scientists are using DNA origami to 3D print structures just nanometers across
A new technique could make it easier to fold strands of DNA into itty-bitty nanostructures on command. DNA origami, which sounds like the weirdest hobby ever, is actually a pretty important scientific technique: Researchers want to be able to produce intricate structures on the nano-scale, so they can interact with human cells and the molecules that make them up. But it's tough to make anything that small, let alone a highly-specialized shape designed to -- for example -- bind to cancer cells and keep them from reproducing.
In a study published Wednesday in Nature, researchers present a new technique for building these complex structures on the smallest possible scale. One day, these tiny, intricate objects could be used to deliver drug therapies, along with other applications not even dreamed up yet.
And now, designing them is fast and easy, thanks to a centuries-old math problem.
To understand the problem tackled by Björn Högberg of the Karolinska Institute, Sweden, and his colleagues, just look to the Seven Bridges of Königsberg. Really.
The problem goes like this: Königsberg (now known as Kaliningrad, Russia) had seven bridges throughout. Would it be possible, mathematicians wondered, to take a walk through the city where each bridge was crossed once and only once?
"The problem we're solving is very similar," Högberg told The Post.
From polygonal mesh to Eulerian path routing of the long scaffold DNA, to the final DNA design and finally the molecular render in DNA, imaged using transmission electron microscopy. (Erik Benson and Björn Högberg)
When scientists try to "3D print" a structure using strands of tiny DNA, they want to optimize the route that DNA takes in order to form the desired structure. Until now, most DNA-based structures have had to be solid and brick-like. But to harness the power of nano-scale objects, you want more dynamic shapes. To create them, you need the DNA to fold itself into a scaffold that maximizes strength and resilience without losing detail by doubling over itself too much.
"We wanted to put the DNA strand on every edge of the polygonal shape once -- and if possible only once -- and then bring it back to its starting point, since it’s a circular molecule," Högberg explained.
With his team's new algorithm -- developed with help from computer scientists at Aalto University in Finland -- it's as easy as rendering a complex shape using normal 3-D printing software. The algorithm is able to optimize a strand of DNA's path to form that shape.
Large models illustrate the DNA nanostructures from the paper. (Erik Benson and Björn Högberg)
For the user, Högberg said, it's suddenly as simple to create 3-D nanostructures as it is to make large-scale ones. Until it comes time to print them out, anyway.
"The learning curve is really improved here, it’s really easy to design them now," he said, "But creating them hasn’t really changed. To actually get them printed out, you have to order the DNA and pipette it together, and that’s of course the barrier to entry for most people."
So DIY biohackers will probably have to wait a while before the team's innovation lets them do complex DNA origami at home. But for now the group is publishing the code for their algorithm in the hopes of helping other labs produce these complex structures more quickly and efficiently.
In commentary written for Nature, physicist Tim Liedl -- who wasn't involved in the study -- praised its findings. "This is not the first study to present polygon meshes constructed from DNA — decades of research have produced dozens of methods for building DNA-based polyhedra and wireframe structures," Liedl writes. "But the current work arguably presents the most versatile and streamlined design method."
By creating a tool that simplifies the production of these structures, Liedl writes, the group is helping to enrich the field, opening the door for more labs to spend their time and energy studying nanostructures.
