Researchers from the USA, University of Bonn and the research institute Caesar in Bonn have used nanostructures to construct a tiny machine that constitutes a rotatory motor and can move in a specific direction. The researchers used circular structures from DNA.
used structures made of DNA nanorings. The two rings are linked like a chain. "One ring fulfills the function of a wheel, the other drives it like an engine with the help of chemical energy", explains Prof. Dr. Michael Famulok from the Life & Medical Sciences (LIMES) Institute of the University of Bonn.
The tiny vehicle measures only about 30 nanometers (millionths of a millimeter). The "fuel" is provided by the protein "T7 RNA polymerase". Coupled to the ring that serves as an engine, this enzyme synthesizes an RNA strand based on the DNA sequence and uses the chemical energy released during this process for the rotational movement of the DNA ring. "As the rotation progresses, the RNA strand grows like a thread from the RNA polymerase", reports lead author Dr. Julián Valero from Famulok's team. The researchers are using this ever-expanding RNA thread, which basically protrudes from the engine as a waste product, to keep the tiny vehicle on its course by using markings on a DNA-nanotube track.
Attached to this thread, the unicycle machine covered about 240 nanometers on its test drive. "That was a first go", says Famulok. "The track can be extended as desired." In the next step the researchers are not only aiming at expanding the length of the route, but also plan more complex challenges on the test track. At built-in junctions, the nanomachine should decide which way to go. "We can use our methods to predetermine which turn the machine should take", says Valero with a view towards the future.