Carbon nanotubes are one-atom thick rolls of graphite 100,000 times smaller than a human hair yet stronger than steel. They are used to reinforce plastics, ceramics, or concrete; are excellent conductors of electricity and heat; and are sensitive chemical sensors. However, a nanotube's surface also contains thousands of atoms that could react with the human body in unknown ways. Tests on mice have shown that nanotube inhalation results in severe lung inflammation coupled with an early onset of fibrosis. The tubes' durability raises additional concern about proper disposal and cleanup. In 2008, Star and Kagan reported in Nano Letters that carbon nanotubes deteriorate when exposed to the plant enzyme horseradish peroxidase, but their research focused on cleanup after accidental spills during manufacturing or in the environment.
For the current study, the researchers focused on human MPO because it works via the release of strong acids and oxidantssimilar to the chemicals used to break down carbon nanotubes. They first incubated short, single-walled nanotubes in an hMPO and hydrogen peroxide solutionthe hydrogen peroxide sparks and sustains hMPO activityfor 24 hours, after which the structure and bulk of the tube had completely degenerated. The nanotubes degenerated even faster when sodium chloride was added to the solution to produce hypochlorite, a strong oxidizing compound known to break down nanotubes.
After establishing the effectiveness of hMPO in degrading carbon nanotubes, the team developed a technique to prompt neutrophils to attack nanotub
|Contact: Morgan Kelly|
University of Pittsburgh