Carbon nanotubes pass initial medical tests

Researchers at Rice University have found that carbon nanotubes will pass through the bloodstream of animals in lab tests, an early indication that nanotubes might one day be used to deliver medicine.

In the tests, the researchers found that the nanotubes injected into lab animals mostly ended up in the liver within 24 hours, with a few samples ending up in the kidneys.

"We sampled tissues from a dozen organs, and found significant amounts of nanotubes only in the liver," Bruce Weisman, a professor of chemistry, said in prepared statement. "The liver naturally removes drugs or compounds from the blood, so this is what we expected to find."

The tests are part of what will likely will be year's worth of medical testing on carbon nanotubes. The tubes, which measure only a few nanometers in length and 1 nanometer in diameter, are potential candidates for delivering medicines in a pinpoint fashion inside the body. (A nanotube is a billionth of a meter; a human hair is about 60,000 nanometers wide.)

Nanotubes also give off light, so they potentially could serve as markers and attach themselves to early waves of tumor cells that don't show up in conventional medical tests. In the current test, the researchers noted that the nanotubes continued to emit light inside the test animals.

Nobel Prize winner Richard Smalley, who taught at Rice before dying of cancer last year, was one of the primary advocates of exploiting the properties of nanotubes.

Researchers at the university and elsewhere, however, are also examining the potential toxicity and side effects of nanotechnology.