Carbon nanohorns could provide a new delivery system for unstable drugs.

Japanese researchers are making progress towards potential new drug delivery systems using unusually small nanotube-like structures. The structures, known as nanohorns, could one day help unstable drugs reach their cellular targets, and have yet to show signs of the health risks widely reported for larger nanotubes.

Sumio Iijima, professor of materials science and engineering at Meijo University, Nagoya, is investigating nanohorns that aggregate in solution rather like the petals on a dahlia. Their small size might make them well suited to passing across cell membranes, suggests Iijima.

So far, they have looked at the way that nanohorns take up dexamethasone - a commonly prescribed drug used to treat arthritis, asthma and allergies - and how they release it in vitro.

Iijima, who discovered nanotubes in 1991, and whose team is now working with nanohorns as part of a five-year project, is well aware of the associated health risks with nanoparticles (p21). The team know they must look out for similar problems with their system. So far, they stress, they have found no signs of toxicity.

Vikki Allen