Inspired by full-sized mechanical parts like hinges and pistons, researchers at Ohio State University have designed pieces of DNA that could eventually be used to construct nano-scale robots.
The new paper, which now appears in PNAS, is the first to show that macroscale design principles can also be applied to DNA to produce intricate, dynamic, and controllable components for molecular-scale robots. Should this research translate to actual real-world applications, nanobots could be made to deliver medicine inside the body, fight infections, repair cells, and perform nanoscale biological measurements. And like the robotic "transformers" of scifi, these origami-like machines could "re-fold" and acquire new shapes for alternate tasks.
"I'm pretty excited by this idea," noted lead researcher Carlos Castro in an Ohio State release. "I do think we can ultimately build something like a Transformer system, though maybe not quite like in the movies. I think of it more as a nano-machine that can detect signals such as the binding of a biomolecule, process information based on those signals, and then respond accordingly—maybe by generating a force or changing shape."
To make it work, the researchers applied an established process called DNA origami where long strands of DNA are coaxed into folding into different shapes. From there, the're secured with "staples" (or "glue strands") made from shorter strands of DNA. The resulting structures are, in theory, stable and strong enough to perform basic tasks, like carrying small amounts of medicine inside a DNA container for eventual release. The keys to the new study were in making the parts of the structure more flexible, and in "tuning" the DNA so that the machines' movements could be reserved and repeatable.
The Ohio University release explains:
The researchers dot their structures with synthetic DNA strands that hang off the edges like the awning of a roof. Rather than join portions of the machine together permanently, these strands are designed to act like strips of hook and loop fasteners—they stick together or unstick depending on chemical cues from the machine's surroundings.
In the lab, [the researchers] took long strands of DNA from a bacteriophage—a virus that infects bacteria and is harmless to humans—and "stapled" them together with short strands of synthetic DNA.
First, they joined two stiff DNA "planks" with flexible staples along one edge to create a simple hinge. Castro likened the process to "connecting two wooden 2x4's with very short pieces of string along the 4-inch edge at one end."
They also built a system that moved a piston inside a cylinder. That machine used five planks, three hinges and two tubes of different diameters—all made from pieces of double-stranded and single-stranded DNA.
Looking ahead, the researchers are hoping to expand the "programmable motion" designs of DNA origami mechanisms and scale up production for further development.
Images: Ohio State University/Castro et al.