Chemical ‘wrapped’ Taxol Bristle Ball may Help Clog Cancer

by VR Sreeraman on Sep 14 2007 12:55 PM

Chemists at Rice University say that they have devised a technique to create tiny spheres comprising of dozens of molecules of the anti-cancer drug paclitaxel by using gold nanoparticles.

The investigators claim that the tiny balls they have created are many times smaller than a living cell that literally bristles with the drug sold under the brand name Taxol, which prevents cancer cells from dividing by jamming their inner works.

"Paclitaxel is one of the most effective anti-cancer drugs, and many researchers are exploring how to deliver much more of the drug directly to cancer cells," said lead researcher Eugene Zubarev, the Norman Hackerman-Welch Young Investigator and assistant professor of chemistry at Rice.

"We looked for an approach that would clear the major hurdles people have encountered -- solubility, drug efficacy, bioavailability and uniform dispersion -- and our initial results look very promising," he added.

Paclitaxel—used to treat breast, ovarian and other cancers—slows down the growth of tumours in some patients by decelerating the process of cancer cells’ division. But since the drug works on all cells, it also tends to inhibit the division of healthy cells.

The researchers say that it is due to this problem with paclitaxel use that patients undergoing chemotherapy sometimes suffer side effects like hair loss and suppressed immune function.

"Ideally, we'd like to deliver more of the drug directly to the cancer cells and reduce the side effects of chemotherapy. In addition, we'd like to improve the effectiveness of the drug, perhaps by increasing its ability to stay bound to microtubules within the cell," Zubarev said.

He worked with graduate student Jacob Gibson to develop the new drug delivery system that centres on a tiny ball of gold, barely wider than a strand of DNA.

The researchers first designed a chemical "wrapper" to shroud the drug’s key, located on the face of each bristle, in order to protect it from any chemical reactions. With the wrapped version of the drug, they undertook a series of reactions to attach the drug to linker molecules that were attached to the ball.

In the final step of the reaction, the researchers dissolved the wrapper to restore the drug’s key. "We are already working on follow-up studies to determine the potency of the paclitaxel-loaded nanoparticles. Since each ball is loaded with a uniform number of drug molecules, we expect it will be relatively easy to compare the effectiveness of the nanoparticles with the effectiveness of generally administered paclitaxel," Zubarev said.

The research has been reported in the Journal of the American Chemical Society.