A team of Swedish and American scientists has shown for the first time that carbon nanotubes can be broken down by an enzyme myeloperoxidase (MPO) found in white blood cells. Their discoveries are presented in Nature Nanotechnology and contradict what was previously believed, that carbon nanotubes are not broken down in the body or in nature. The scientists hope that this new understanding of how MPO converts carbon nanotubes into water and carbon dioxide can be of significance to medicine.
"Previous studies have shown that carbon nanotubes could be used for introducing drugs or other substances into human cells," says Bengt Fadeel, associate professor at the Swedish medical university Karolinska Institutet. "The problem has been not knowing how to control the breakdown of the nanotubes, which can caused unwanted toxicity and tissue damage. Our study now shows how they can be broken down biologically into harmless components."
Carbon nanotubes are a material consisting of a single layer of carbon atoms rolled into a tube with a diameter of only a couple of nanometres (1 nanometer = 1 billionth of a metre) and a length that can range from tens of nanometres up to several micrometers. Carbon nanotubes are lighter and stronger than steel, and have exceptional heat-conductive and electrical properties. They are manufactured on an industrial scale, mainly for engineering purposes but also for some consumer products.
Carbon nanotubes were once considered biopersistent in that they did not break down in body tissue or in nature. In recent years, research has shown that laboratory animals exposed to carbon nanotubes via inhalation or through injection into the abdominal cavity develop severe inflammation. This and the tissue changes (fibrosis) that exposure causes lead to impaired lung function and perhaps even to cancer. For example, a year or two ago, alarming reports by other scientists suggested that carbon nanotubes are very s
|Contact: Katarina Sternudd|