Scientists at the Cockrell School of Engineering at the University of Texas have built and tested what appears to be the world's smallest, fastest, and longest-running nanomotor yet – so small that it could fit inside a single cell. The advance could be used to power nanobots that would deliver specific drugs to individual living cells inside the human body.

In the distant future, when faced with a cancer diagnosis, we might be able to simply ingest a "magic pill" filled with hordes of miniscule nanobots that target individual cancerous cells with drugs and leave the healthy ones unharmed. To power those robots, we need a nanoscale-sized motor that's capable, sufficiently long-lived, and flexible enough for a wide range of applications.

A team of researchers led by Prof. Donglei Fan has produced a nanomotor that might just satisfy those requirements. The device is simple in its structure, being composed of only three parts, which are brought together one by one using a patent-pending technique relying on AC and DC electric fields.

The resulting nanodevice is under 1 micrometer in size in all three dimensions, meaning it's small enough to fit inside a single cell. It was also shown to be significantly more long-lived than previous designs, with the ability to convert electrical energy to mechanical energy and maintain a speed of 18 thousand RPMs – which is comparable to the speed of a jet engine – for an impressive 15 hours of continuous operation.

The motor could power nanobots capable of targeting individual cells (Image: University of Texas)

The researchers can also keep surprisingly good control of the motor: it can be turned on and off, made to rotate clockwise or counterclockwise, and even run in synch with other motors for a more powerful output.

When the nanomotor's surface is coated with biochemicals, it releases them with a force proportionate to its current speed. So, in principle, the motor by itself could already be an effective drug delivery mechanism on the nanoscale.

"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,” says professor Donglei "Emma" Fan, who led the team. "We believe it will help advance the study of drug delivery and cell-to-cell communications."

The next step for the team is to test how precisely the nanomotor can deploy drugs to nearby cells. Eventually, the researchers hope they will be able to use their devices to power nanobots that can pick out individual diseased cells inside the human body for highly targeted drug deliveries.

A paper detailing the nanomotor is published in the journal Nature Communications.

The video below illustrates what applications the nanomotors could find in the future.

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