Engineers in Texas say they've successfully built the world's smallest and fastest nanometer, a tiny synthetic engine that could have applications in medicine.

Such miniature machines could someday power their way through the human body to deliver insulin as needed in diabetes sufferers, or home in on cancer cells to destroy them without causing harm to healthy cells, the researchers at the University of Texas as Austin say.

Their high-speed nanomotor converts electrical energy to mechanical motion in a device 500 times smaller than a grain of table salt, they report. The nanomachine is small enough at slightly less than 1 micrometer to sit inside a single human cell.

Whereas most nanomotors created to date spin at speeds of between 14 rpm and 500 rpm and grind to a halt in just a few minutes, the Texas device can spin at speeds of 18,000 rpm for as long as 15 hours, the researchers reported.

That as fast as an the rate at which an aircraft jet engine spins.

As it does so it can pass through liquids while both mixing and distributing drugs or other biochemicals, the scientists said.

When its surface is coated with drugs, they are released as the nanomotor spins, and the faster it spins the faster the biochemical are released.

"We were able to establish and control the molecule release rate by mechanical rotation, which means our nanomotor is the first of its kind for controlling the release of drugs from the surface of nanoparticles," mechanical engineering Professor Donglei (Emma) Fan, the projects' lead researcher, said. "We believe it will help advance the study of drug delivery and cell-to-cell communications."

The nanomotor consist of just three parts, a microelectrode, a nanomagnet, and a nanowire which is the part which spins and can deliver drugs into a biological target.

It was assembled using a technique developed by Fan that uses electrical fields to move and assemble the nanomotor's component parts one at a time.

Created at the university's Cockrell School of Engineering, the nanomotor has only been tested in a non-biological setting so far, but Fan and her colleagues say they hope to test the device in proximity to live cells to measure its ability to deliver molecules of drugs or biochemical in a controlled manner.