At Stanford University researchers have developed a method to use carbon nanotubes to deliver chemotherapy drugs to a tumor, which results in a more localized effect than a typical injection.
The researchers used nanotubes that they had coated with polyethylene glycol (PEG), a common ingredient in cosmetics. The PEG they used was a form that has three little branches sprouting from a central trunk. Stuffing the trunks into the linked hexagonal rings that make up the nanotubes created a visual effect that Dai [Hongjie Dai, professor of chemistry] described as looking like rolled-up chicken wire with feathers sticking out all over. The homespun sounding appearance notwithstanding, the nanotubes proved to be highly effective delivery vehicles when the researchers attached the paclitaxel to the tips of the branches.
Dai’s team has found in earlier work (Proceedings of the National Academy of Sciences, Vol. 105, No. 5, 1410-1415, Feb. 5, 2008) that coating nanotubes with PEG was an effective way to keep the nanotubes circulating in the bloodstream for up to 10 hours, long enough to find their way to the target location and much longer than free medication would circulate. Although attaching the paclitaxel to the PEG turned out to reduce the circulation time, it proved to still be long enough to deliver a highly effective dose inside the tumor cells.
All blood vessel walls are slightly porous, but in healthy vessels the pores are relatively small. By tinkering with the length of the nanotubes, the researchers were able to tailor the nanotubes so that they were too large to get through the holes in the walls of normal blood vessels, but still small enough to easily slip through the larger holes in the relatively leaky blood vessels in the tumor tissue.
That enabled the nanotubes to deliver their medicinal payload with tremendous efficiency, throwing a therapeutic wrench into the cellular means of reproduction and thus squelching the hitherto unrestrained proliferation of the tumor cells.
Press release: Slipping through cell walls, nanotubes deliver high-potency punch to cancer tumors in mice
Abstract in Cancer Research…