Nanotubes To Deliver Chemo Where And When It’s Needed

Unusually large and roomy carbon nanotubes could deliver chemotherapy drugs directly to tumors and release them on command, according to a new study (Nano Lett., DOI: 10.1021/nl301865c). A harmless magnetic field triggers the nanotubes to release drugs once inside tumor cells, which should protect the rest of the body from the drugs’ toxic side effects, researchers say.

Since the 1980s, researchers have developed various nanoscale vessels to transport anticancer drugs through the body. Some of these carriers have made it into the clinic. However, biologist John Marshall of Brown University says that researchers are unable to externally control drug release. Previous attempts have proven only partially successful or impractical, such as one delivery vehicle triggered to open by ultraviolet radiation, which is harmful and does not penetrate tissue.

Marshall, Brown nanomaterials expert Jimmy Xu, and colleagues synthesized nanotubes using chemical vapor deposition. Unlike traditional nanotubes, which have a diameter of around 1 nm, these nanotubes had a diameter of about 40 nm and so, the researchers figured, would have room to carry drug molecules. In fact, they are spacious enough to carry two drugs at once. The team filled the nanotubes with a temperature-sensitive hydrogel loaded with the chemotherapeutic agents paclitaxel and C6-ceramide. When researchers applied an alternating magnetic field, it induced an alternating electric current in the nanotubes. The nanotubes’ electrical resistance to that current generated heat that liquefied the gel, releasing the loaded drugs.

The team tested the nanotubes on pancreatic cancer tissue. After waiting 12 hours for the cells to take up the nanotubes, the researchers turned on the magnetic field. Forty-eight hours later, more than 70% of the cancer cells had died. To kill the same fraction of cells without the aid of nanotubes, the researchers had to use 100 times as much drug.