Study Finds No Adverse Effects From Nanotubes in Bloodstream, Liver

By Jade Boyd

In the first experiments of their kind, researchers at Rice University and the University of Texas M.D. Anderson Cancer Center have determined that carbon nanotubes injected directly into the bloodstream of research lab animals cause no immediate adverse health effects and circulate for only a little more than an hour before they are removed by the liver.

The findings are from the first in vivo animal study of chemically unmodified carbon nanotubes, a revolutionary nanomaterial that many researchers hope will prove useful in diagnosing and treating disease. “We sampled tissues from a dozen organs and found significant amounts of nanotubes only in the liver,” says lead author Bruce Weisman, professor of chemistry. “The liver naturally removes drugs or compounds from the blood, so this is what we expected to find.” The researchers also found trace amounts of nanotubes in the kidneys—another common expulsion route for drugs. There was no evidence that nanotubes remained in other tissues in the body.

“The early results are promising for anyone interested in using carbon nanotubes in biomedical applications,” says co-author Steven Curley, professor of surgical oncology and chief of gastrointestinal tumor surgery at M.D. Anderson. “We are particularly pleased that the fluorescent effect remains intact in our application, because this makes it easier to see where the nanotubes end up, and it opens the door to some exciting diagnostic and therapeutic applications.”

In one follow-up project, researchers are working on methods that will allow nanotubes to circulate longer following injection so that the nanotubes can be more easily targeted to specific organs. In another, the researchers are tracking the longer-term behavior and effects of nanotubes in research lab animals.

The research appeared in the Nov. 29, 2006, issue of the Proceedings of the National Academy of Sciences and was funded by the Alliance for NanoHealth, NASA, Rice University’s Center for Biological and Environmental Nanotechnology, the National Science Foundation, the Welch Foundation and the National Institutes of Health.