In an effort to improve the application of drugs inside the human body and target specific areas for therapy, scientists have found a way to direct human cells using tiny metal motors. The microscopic metal engines, measuring just a few thousand nanometers wide -- or about 1/33 the width of a human hair -- are propelled with ultrasound and steered using magnets.

Scientists have successfully installed the tiny motors into synthetic laboratory apparatus before, but this is the first time “nanomotors” have been tested in living human cells.

“This research is a vivid demonstration that it may be possible to use synthetic nanomotors to study cell biology in new ways,” Tom Mallouk, a physics and chemistry professor at Penn State University and a lead researcher on the project, said in a statement. “We might be able to use nanomotors to treat cancer and other diseases by mechanically manipulating cells from the inside. Nanomotors could perform intracellular surgery and deliver drugs noninvasively to living tissues.”

Mallouk and his fellow researchers from Penn State University and the Weinberg Medical Physics in Maryland inserted the nanomotors into human HeLa cells, a type of “immortal cell” derived from cervical cancer cells and often used in scientific research. According to researchers, the cells “ingested” the tiny motors, which then became part of the cells and which scientists could then use to manipulate the cells’ activity.

The study, published in the journal Angewandte Chemie International Edition, noted how researchers can direct the nanomotors to act like “egg beaters” -- whipping up everything inside a cell’s walls to homogenize the cell -- or like a “battering ram” to puncture the cell membrane.

Scientists can control the motors independently using ultrasonic pulses and magnets.

“As these nanomotors move around and bump into structures inside the cells, the live cells show internal mechanical responses that no one has seen before,” Mallouk said. “Autonomous motion might help nanomotors selectively destroy the cells that engulf them. If you want these motors to seek out and destroy cancer cells, for example, it's better to have them move independently. You don't want a whole mass of them going in one direction.”

The researchers conjured up the image of a future in which “Fantastic Voyage-style” treatment is conventional.

Nanomotors isn’t the only recent breakthrough in cellular exploration. In January, engineers developed something called a “bio-bot,” a microscopic biological machine powered by heart cells and propelled by a tail that can navigate the viscous insides of micro-organisms on its own.

Bio-bots were modeled after flagella, single-celled creatures with long tails. The heart cells cultured at the head and tail of the synthetic organism propel the bio-bot forward as they contract.

Researchers say cell-powered bio-bots could be used to detect chemicals or target certain kinds of cells, such as cancer cells, inside the human body.