Asbestos increases the risk for certain cancers. The fibers are thought to do so by skewering cells, setting off chemical reactions that lead to inflammation, DNA damage and cell death. Some studies have suggested carbon nanotubes might have similar effects—because they're long and spiky, like asbestos. But why would a cell draw in a nanotube, essentially impaling itself on a microscopic lance?

To find out, researchers exposed mouse and human cells to carbon nanotubes. They saw that the cells frequently engulfed the tubes—almost always tip-first. They then simulated that sword-swallowing maneuver on a computer. And they concluded that the round tips of nanotubes feel like bite-sized spheres, which cells commonly ingest. But once the cell senses the nanotube isn’t bite-size? It's too late. It can't stop sucking it in. The finding is in the journal Nature Nanotechnology. [Xinghua Shi et al., "Cell entry of one-dimensional nanomaterials occurs by tip recognition and rotation"]

As nanotubes may have medical applications, making them safe is key. And there may be a way to keep cells from biting off more than they can swallow—snip off the nanotubes' rounded tips. In one such simulation, the cells left the tubes alone—meaning we may get to have our nanotubes, without eating them, too.

—Christopher Intagliata

[The above text is a transcript of this podcast.]

[Scientific American is part of the Nature Publishing Group.]