Researchers at Penn State University have placed nanoparticles inside living human cells and been able to direct the movement of the particles through the use of both ultrasonic waves and magnetic forces. While similar demonstrations have been conducted in a test tube (in vitro), this marks the first time that this kind of work has succeeded inside a live human cell.
Once the nanoparticle motors start moving about inside them, the researchers observed that the cells begin to react in ways not previously observed.
"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," Tom Mallouk, a professor of materials chemistry and physics at Penn State, said in a press release.
(A video showing how the nanomotors move around inside the cells is below.)
While the over-exuberant press release likened the work to the 1960s sci-fi movie “Fantastic Vogage”, it does not involve anything remotely close to plot details of that movie. (It’s time to put aside this misleading comparison once and for all.) However, this research does invite comparisons to a proposal out of Stanford University back in 2012 in which small antennas on a microchip could receive magnetic fields that propel the chip through the blood stream.
The new nanomotor research, which was published in the 10 February international edition of the journal Angewandte Chemie ("Acoustic Propulsion of Nanorod Motors Inside Living Cells"), used HeLa cells, a type of human cervical cancer cells. The HeLa cells ingest the nanoparticles. Once a high level of ultrasonic waves is focused on the nanoparticles, they begin to move about. If the level is too low, the nanoparticle will not react to the ultrasonic waves.
If a cancer cell were to ingest these nanoparticles, they could be moved around fast enough so that they acted as a sort of high-tech food processor, making a homogenized mix of the cell’s contents.
But Mallouk also sees a more refined role for them. “We might be able to use nanomotors to treat cancer and other diseases by mechanically manipulating cells from the inside,” said Mallouk in the release. “Nanomotors could perform intracellular surgery and deliver drugs noninvasively to living tissues."
It is through the combination of the ultrasonic waves and the magnetic forces that the researchers have been able to make the nanoparticles move autonomously from each other. The ultrasonic waves manage to move the nanoparticles forward or spin them around. But the magnetic forces are used to actually steer them.
"Autonomous motion might help nanomotors selectively destroy the cells that engulf them," Mallouk said. "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."
Image: Mallouk Lab/Penn State University
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.