Of all the great The Magic School Bus episodes, the best is assuredly the one where Ms. Frizzle takes her student on a driving tour of the circulatory system, bouncing off red blood cells and whatnot. Now that you're feeling sufficiently nostalgic, think about this: What if, instead of educating, Ms. Frizzle had spent her time fighting off cancer cells?
While it doesn't involve school buses or magic, new nanotech research shows how such targeted cellular treatment may be possible. For the first time, metallic nanomotors were manipulated in living cells by a team of Penn State researchers. Using ultrasonic vibrations for control, the team demonstrated how such nanomotors can manipulate—or at least bump around—actual, living cells.
"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," said Penn State professor Tom Mallouk, a co-author of the report, titled "Acoustic Propulsion of Nanorod Motors Inside Living Cells," to be published in Angewandte Chemie.
Gold-ruthenium nanomotors inside of a HeLa cancer cell. Image: Mallouk lab, Penn State
Nanobots that can manipulate and fix the body from the inside are a favorite subject of sci-fi, but as nanotech research continues to boom, they're looking more real than ever. In this case, the team studied how gold nanorods would interact inside HeLa cancer cells. After being absorbed by the cells, the nanorods could be induced to vibrate around the cells using ultrasonic frequencies. Depending on how much power was used, the rods either bumped around, or could vibrate so wildly as to destroy a cell's organelles or puncture its membrane. Such a targeted, internal approach has obvious oncological potential.
"This research is a vivid demonstration that it may be possible to use synthetic nanomotors to study cell biology in new ways," Mallouk said in a release. "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."
Aside from the ability to destroy cells, what's notable about the work is the fact that they're not toxic. Some early work on nanomotors relied on chemical propulsion, which wouldn't work in living cells. But with the development of ultrasonic propulsion, which can also be magnetically guided, nanomotors could finally be tested in vivo.
As you can see in the above video, the team showed a fair bit of control over cells and the nanomotors themselves. Curiously, they found that the nanomotors could feasibly move independently of one another, which offers promise of even more precise targeting. And as their movement gets more refined, the potential for medical applications increases, although human trials are still a ways down the road.
"One dream application of ours is Fantastic Voyage-style medicine, where nanomotors would cruise around inside the body, communicating with each other and performing various kinds of diagnoses and therapy," Mallouk said. "There are lots of applications for controlling particles on this small scale, and understanding how it works is what's driving us."
Precision is incredibly important to good medicine. It's an obvious statement, but one needn't look further than our increasing use of broad-spectrum antibiotics to see the downside of increasing generalization in treatment. (Of course, antibiotics that work are superior to ones that bacteria are resistant to.) In that vein, nanotech offers incredible promise—and whether it's toxin-absorbing nanosponges, nanoparticle drug patches, self-assembling nanotrains, spermbots, nanovolcanoes, or nanomotors, that promise is getting closer to paying off.