Researchers have created and programmed robots the size of single molecules that can move independently and even make tiny products themselves.
Based on strings of reprogrammed DNA, the robotic 'spiders' can move autonomously through a specially-created, two-dimensional landscape.
The spiders acted in rudimentary robotic ways, showing they are capable of starting motion, walking for awhile, turning, and stopping.
"Can you instruct a biomolecule to move and function in a certain way? Researchers at the interface of computer science, chemistry, biology and engineering are attempting to do just that," says Mitra Basu, a program director at the National Science Foundation supporting the research.
Just four nanometers in diameter, the robots can move slowly, covering 100 nanometers - about 100 steps - in half an hour or so. It's a significant improvement over previous DNA walkers, which were capable of only about three steps.
The robots move along a specially created track made of 'unzipped' DNA, linking with each segment as they go and then unbinding. They stop when they reach a DNA segment from which they can't unbind.
The researchers believe the nanorobots may someday have important medical applications. "This work one day may lead to effective control of chronic diseases such as diabetes or cancer," Basu says.
They could in theory be programmed to target cancerous cells and deliver medication.
The work was carried out by researchers from Columbia University, Arizona State University, the University of Michigan and the California Institute of Technology. Details appear in Nature.