DNA Robot Waves at the Future

Dec. 7, 2006 — You need a special microscope to see it, but this DNA robot has an arm and it can practically wave at you.

It's more of a Frankenstein-like "from the shoulder" kind of wave, than a royal pivot of the wrist. But the movement is the first good example of controlled motion in a nano-sized robot.

"We can control it at that scale and that's kind of exciting," said professor Nadrian Seeman of New York University, who along with Baoquan Ding published the results in today's issue of Science.

For nearly 25 years, scientists have been thinking about building devices smaller than a cell that could perform any number of duties. For example they could switch between two states representing 1's and 0's to perform calculations and store data the way computers do now.

Or, like factory robots, the nano-sized machines could assemble tiny circuits that could be used in nano-devices or nano-robots. They could even assemble arrangements of enzymes and proteins and other cellular components to build artificial cells.

But the success of this area of nanotechnology requires that such machines precisely place the necessary components in the right places.

"To have control of the geometry is the key thing," said Hao Yan, an assistant professor in the department of chemistry and biochemistry at Arizona State University in Tempe. Yan is not associated with the research project.

Because DNA has built-in coding that allows it to recognize other molecules, scientists have been experimenting with using it as a kind of skilled laborer to construct nano-scale devices.

By tinkering with the four base sequences in DNA, scientists can manipulate pieces of DNA to attract other pieces and begin to assemble a kind of DNA machine.

But for a machine to work, it needs to have both mobile and stationary parts and that's what Seeman and Ding have done.

The researchers built a two-dimensional scaffolding of DNA and then inserted a component that contained an arm also made of DNA.

The "shoulder," or the place where the arm connected to the component contains a particular sequence of DNA. With this sequence, the arm pointed up. When the researchers changed the sequence, the arm pointed down.

"This is the first work to show that you can incorporate mobile parts into a 2-D arrangement of DNA," said Chengde Mao, assistant professor at Purdue University in West Lafayette, IN.

The next step, says Seeman, is to incorporate more arms in the robot and manipulate each of them in a slightly different way at the same time.