Nanotubes mimic protein channels
03 November 2005
Water passes through nanotube nicotine patches faster than predicted and offers new drug delivery prospects, say US scientists.
Bruce Hinds at the University of Kentucky has made biological membranes with carbon nanotubes, to mimic protein channels. The tubes were virtually frictionless and the flow of water through them was four to five orders of magnitude faster than conventional fluid dynamics had predicted.
Water flows through the nanotube membranes and biological channels at the same speed. 'We can mimic what happens in protein channels. This is one of the first easily made man-made structures that can do that,' said Hinds.
The membranes were tested as transdermal drug delivery systems, often used as nicotine patches. Hinds said that ensuring the nanotubes stayed outside the body was important to avoid biocompatibility problems, 'We're not sure what nanotubes do,' he said.
Fast flow in nanotubes was predicted theoretically by Gerhard Hummer at the National Institutes of Health, but had not been proven experimentally. 'Naively, one might have expected nanopores to either become instantly plugged or, at best, accommodate only a very small flow rate. Instead, fluid flow through the nanopores appears to be nearly frictionless,' Hummer told Chemistry World. The experimental verification of his theory 'opens up a whole range of application possibilities, including filtration and reverse osmosis,' he said.
The carbon nanotube transdermal patches can control the flow of drugs to the skin.
Hinds hopes to exploit the fast flowing capabilities of the membranes further. 'Being very futuristic, there's no reason not to make an artificial virus where the nanotubes have different chemistry on each end and high flow through the middle,' he said. Katharine Sanderson
M Majumder et al, Nature, 2005, 438, 44