A tiny robot made from strands of DNA could pave the way for mini-machines that can dive into the human body to perform surgeries, among other futuristic applications.
While DNA-based robots have been made before, this latest real-life micromachine is the first one that researchers have successfully programmed to follow instructions on where to move. Once assembled, the robot can take multiple steps without any outside help, according to lead researcher Andrew Turberfield, a professor at the University of Oxford.
"Turberfield's group has figured out a beautiful way to automate the movement of a strand of DNA along a track," said William Sherman, an associate scientist at Brookhaven National Laboratory, who was not involved in the study.
When thinking about robots, many of us picture humanlike machines with metal moving parts, like Rosie from "The Jetsons." DNA bots operate along similar lines, but on the molecular scale with chemical versions of motors and sensors.
The thinking behind scientists' interest in super-small DNA bots is that in order to replicate some amazing abilities in nature, one must go very small. The problem is that "as we build smaller and smaller parts, we are getting to the point where it is harder to build things that are below a certain scale," said Nadine Dabby, a graduate student at the California Institute of Technology, who was not involved in the study. "So a lot of people have become interested in something called self-assembly — which, essentially, is the idea that you mix a couple of things together in a tube and it just builds itself."
Enter the DNA molecule. "DNA happens to be a molecule that scientists understand a lot about, and it also has a built-in way to control it, or program it, and it is very easy to work with," Dabby said. "By specifying the sequence of a molecule of DNA we can control what it will bind to or interact with," she added, referring to the fact that specific DNA sequences, or genes, hold instructions for making proteins that ultimately carry out bodily functions.
Takes instruction well
Like DNA bots that have been made in the past, Turberfield's consists of strands of DNA with each piece having its own purpose. The key to this new DNA robot is a so-called fuel hairpin — a molecule programmed with instructions for the robot.
"Information is programmed into the design of the base sequences of the DNA strands," Turberfield said.
Turberfield and his colleagues tested out their robot on a molecular track with various branches. The hairpin, which also served as a chemical energy source to propel the bot along the course, held instructions for which way the robot should move next, allowing it to select between left or right branches at a junction in the track.
The ability to precisely control the robot's movement means this approach may work for transporting pharmaceuticals or other materials in the body, the researchers said.
Before the technology reaches its full potential, several challenges must be overcome, Brookhaven's Sherman said. These include learning how to combine different elements of DNA-based elements — DNA computers, structures, and machines — into one machine.
Another challenge will be to "improve our control of the interactions of DNA with other chemicals and materials, so that the sophisticated DNA devices we are developing can interact with the rest of the world," Sherman said.
The researchers detailed their findings in the March 9 issue of the journal Nano Letters.