An Enzyme Turned Engine

Researchers have long envied complex gadgets in nature, such as the protein-based motors that flex muscles. Now, the manmade and biological are joining forces. In the 24 November issue of Science, researchers unveil a nanoscale propeller made by fastening tiny metal bars atop a protein motor. Researchers think the approach may pave the way to a host of hybrid nanotech devices.

Tiny mechanical contraptions are nothing new. Over the last 20 years, researchers have perfected a host of techniques to carve silicon and other materials into electromechanical devices just micrometers in size. But making them work at the nanometer scale has proven challenging. That's where biology comes in. Cornell University's Carlo Montemagno and his colleagues have borrowed a biological motor enzyme called ATP synthase, which helps produce adenosine triphosphate, the chemical fuel inside cells. ATP synthase is a mere 8 nanometers across and 14 nanometers long.

To put the enzyme to work as a propeller, the team first created a surface covered with tiny nickel posts. They then genetically engineered the ATP synthase proteins to bind to nickel posts, orienting the motors upright. Next, the researchers attached gluelike molecules to the top of a rotating shaft that naturally sticks out of the enzyme. Finally, they dabbed more molecular glue in the center of the metal propeller blade, binding it to the shaft. Because ATP can be used to power the shaft, the group was able to set the tiny propellers whirling by simply adding ATP to a solution covering the motors. (Click here for a movie showing the propeller spinning and sucking in a dust particle that later reappears at the surface. Downloading may take several minutes.)

Applications aren't likely to take off from these nanochoppers any time soon, even though Montemagno notes that the tiny propellers could become useful for dispensing drugs or storing data. Nevertheless, says Viola Vogel, head of the nanotechnology center at the University of Washington, Seattle, the effort is important because it heralds a new integration of manmade devices with biological systems. "This is a nice example of this merger," she says. "Many research teams are headed in this direction."

Related sites

The Montemagno Research Group

More movies of the ATPase-powered nanomachine