14:43 16 December 2003

Carbon nanotubes show drug delivery promise
NewScientist.com news service
Danny Penman


Carbon nanotubes are adept at entering the nuclei of cells, researchers have discovered, and may one day be used to deliver drugs and vaccines.

The modified nanotubes have so far only been used to ferry a small peptide into the nuclei of fibroblast cells. But the researchers are hopeful that the technique may one day form the basis for new anti-cancer treatments, gene therapies and vaccines.

"Our research is still in its earliest stages, but it shows great promise," says Alberto Bianco, at the CNRS Institute in Strasbourg, France. "The nanotubes seem to migrate mainly to the nucleus, so we can imagine them being used to deliver gene constructs."

"We can also imagine them being used to deliver drugs to specific compartments of the cell," he told New Scientist.
Rapid migration

Off-the-shelf carbon nanotubes were used by Bianco's team as the basis for their 'nano delivery vehicle'. The tubes were modified by heating them for several days in dimethylformamide, which enabled short linking chains of triethyleneglycol (TEG) to be attached. Then, a small peptide was bonded to the TEG molecule.

When the modified nanotubes were mixed with cultures of human fibroblast cells they rapidly entered and migrated towards the nucleus. At low doses the nanotubes appeared to leave the cells unharmed, but as the concentration increased cells began to die.

"The nanotubes do not appear to be highly toxic," says Bianco. "But we do now have to work out what happens to the nanotubes in the body."
Custom delivery

In principle, a wide range of different molecules could be attached to the nanotubes, raising the possibility of an easily customised way of ferrying molecules into cells.

This has begun to excite other researchers. Ruth Duncan, who works on drug delivery mechanisms at Cardiff University, UK, told New Scientist: "There's a lot of evidence that other nanoparticles could be useful in delivering drugs so this is a very interesting and exciting area. But I am completely baffled about how the nanotubes manage to get into the cells."

Duncan says researchers have tried without much success to use buckyballs - a spherical form of carbon nanotubes - as a way of ferrying anti-cancer drugs and radionucleotides into cells.

Journal Reference: Chemical Communications (DOI: 10.1039/b311254c)

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