In the 1966 movie Fantastic Voyage, a microscopic medical team travels through a human body using a shrunken submarine. While shrinking people remains fiction, researchers in California have developed a micromotor that can travel through a mouse's stomach lining - a breakthrough that could allow drugs to be delivered to precisely where they're needed.
Scanning electron microscope (SEM) image of the micromotors (credit: Wei Gao et al)
When we swallow a pill, it travels down the oesophagus to the stomach, where the stomach lining absorbs the drugs. However, unhappy with how little the stomach actually absorbs drugs, engineers at the University of California, San Diego have now developed micromotors that could release the medication much more efficiently.
The scientists put hundreds of these motors into a solution laden with gold nanoparticles, which they then fed to mice. Once they'd arrived inside the mice's stomachs, the zinc motors reacted with the stomach acid to create a stream of tiny bubbles, propelling the motors into the mucous layer lining the stomach wall. After they'd unloaded their cargo, the motors dissolved within a few days, leaving no toxic residues.
It was the first time that the motors had been tested in a living animal. "This initial work verifies that this motor can function in a real animal and is safe to use," says Prof Liangfang Zhang at the UC San Diego. The method proved to be three times as effective at delivering nanoparticles into the mice's stomach lining than when no micromotors were used.
Watch the micromotors in action
In the future, the motors might be able to steer themselves so that they can be targeted more accurately, says Joseph Wang at the UC San Diego. He also thinks that his team’s discovery will enable future nanomachines to perform nanosurgery, drug delivery and even biopsies.
So will we ever be able to navigate the passages of the human body and heal it from the inside like in Fantastic Voyage? Probably not. But who needs to shrink an entire medical team when a nano-ambulance does the job on its own?
By Martin Angler