“Touch-me-not” tubes kill bacteria

Carbon nanotubes, infinitesimally tiny “pipes” thousands of times smaller that a human hair, show great promise for medical applications. However, there has been concern that the tubes might damage human cells.

A Yale research group led by Menachem Elimelech, Ph.D., chair and Roberto C. Goizueta Professor of Environmental and Chemical Engineering, wanted to find out how nanotubes affect E. coli bacteria. Because metallic impurities might lie behind the tubes’ supposed toxicity to human cells, the team thoroughly purified their nanotubes in the laboratory of Lisa D. Pfefferle, Ph.D., professor of chemical engineering.

In the August 28 issue of Langmuir, the scientists report that just one hour of contact with purified nanotubes proved deadly to about 80 percent of E. coli. The authors believe that the tubes killed bacteria by piercing cell walls: the cells looked flattened, and genetic material was seen floating freely in solution. Thinner nanotubes killed bacteria more efficiently, much as sharper objects pierce balloons more easily.

Even antibiotic-resistant pathogens may succumb to nanotubes, which may make new antimicrobial surfaces possible.