The nanomotor -- 500 times smaller than a grain of salt -- is capable of rotating for 15 hours at 18,000 RPMs, the speed of a motor on a jet engine, and for almost a quarter of a million rotations.
The motor is not dissimilar to electric motors found in household appliances in that it is constructed from a rotor, stator and bearings; however, this motor can get down to one-tenth the size of a cell.
The scientists, led by Donglei “Emma” Fan at the University of Texas at Austin, coated the nanomotor with biochemicals and began spinning it to test its ability to release them; the faster the motor spun, the more biochemical was released. This could offer a new controllable approach to drug release in cells.
“Nanorobotics could in future go into people’s bodies and do diagnoses and deliver treatments, but there are many technical barriers to be overcome first. And nanomotors are one important component for such nanorobotics,” said Fan.
“We assembled nanomotors using a bottom up approach. So first we synthesised the different components and then we assembled them together. I employed my recent invention called an electrical tweezer to realise the rotation,” she added. Her patent-pending manipulation technique relies on AC and DC electrical fields and magnetic forces to precisely transport nanoparticles and to operate the nanomotor.
The three-part motor can mix and pump biochemicals and move through liquids. The nanomotors consist of multisegment nanowires, patterned nanomagnets and quadrupole microelectrodes. Arrays of the motors could be synchronised when spun. They were described in a recent issue of Nature Communications.
“The RPM is impressive in that it appears to be faster than has been reported for other nanoscale motors,” commented Andrew Owen, professor of pharmacology at the University of Liverpool, UK. “However, release of a biochemical was only demonstrated between 100 and 250 RPM, so they may not require the maximum speed.”
“The key advantages however appear to be the ability to tune biochemical release from an ordered array of numerous assembled motors, that all rotate in concert,” said Owen. “Probably the most likely short to medium term application for medicine will be provision of the ability to assess the effects of local administration of biological signals to individual cells and this may have application in drug discovery programmes if certain obstacles can be overcome.”