Credit: © 2010 NPG

Organ-specific therapeutics and diagnostics are important goals in the development of medical nanotechnology. Carbon nanotubes are attractive delivery vehicles in this regard because the internal space can carry an active payload, and the external walls can be functionalized to potentially direct their distribution in the body. Now, a collaboration between researchers from Oxford, Barcelona and London has resulted in a demonstration1 that carbon nanotubes can be used to deliver a radioprobe to a specific organ in a mouse.

The team, led by Gerard Tobias, Kostas Kostarelos and Benjamin Davis, first filled the single-walled carbon nanotubes with radiolabelled sodium iodide at high temperature. The ends of the tubes close spontaneously on cooling, trapping the iodide inside. The outside of the nanotubes were then functionalized with a sugar-containing molecule that directed the nanotubes to the lungs of the mice. Radioactive iodide is known to be a very effective emitter for radiotherapy, but its use is limited because it is usually directed to the thyroid gland by a natural protein — meaning that it has so far only been useful in the treatment of thyroid cancer.

Both whole-body imaging and analysis of tissue samples showed that the filled and functionalized nanotubes were able to deliver the radioemitter selectively and without leakage. It is hoped that other modifications of the nanotubes will allow even greater control of the fate of these delivery vehicles and their cargo in vivo.