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The Next Big Thing:
Improving a Key Weapon Against Cancer

Chemotherapy is one of the most potent weapons in the battle against cancer. But because the powerful drugs circulate throughout the body, carried by the bloodstream, they often harm healthy cells while attacking the malignant ones.

photo by Gary Meek Magnetic nanoparticles attached to chemotherapy drugs could increase therapeutic dosages while reducing side effects. Researchers John Zhang and Adam Rondinone prepare a sample of magnetic nanoparticles for analysis by X-ray diffraction. (300-dpi JPEG version - 644k)

Research on nanometer-scale particles with magnetic properties may allow better targeting of chemotherapy, potentially boosting its impact on cancer while reducing effects on healthy cells.

Rina Tannenbaum and John Zhang are pursuing different aspects of a promising new technique that would use magnetic nanoparticles to deliver chemotherapy drugs directly to cancer cells. After injection into the body, the particles would be guided to tumor sites by external magnetic fields. Once there, the particles – some as small as 2.5 nanometers – would bind to the cancer cells and deliver their drug payloads.

"This technique would put the specific drug you need directly into the cells you want to kill, affecting a minimal number of healthy cells," says Tannenbaum, an associate professor in the School of Materials Science and Engineering. "This could make the side effects of chemotherapy much less pronounced and allow you to zap the cancer cells with a higher drug concentration than you could otherwise provide. Both the localization and concentration could be very helpful in treating cancer."

With Georgia Tech colleagues, she works with metallic nanoparticles "capped" by polymeric materials such as polystyrene. The polymer prevents the nanoparticles from aggregating into larger particles and provides locations – reactive sites – at which molecules of the chemotherapy drug can be tethered like skiers behind a powerboat.

Tannenbaum's research so far has yielded good control over particle size, which appears related to polymer concentrations in the one-step chemical reaction forming the nanoparticles.

Though promising, her technique faces important hurdles. The polymer capping must withstand harsh conditions in the body. And chemical bonds between the drug and polymer must be strong enough to hold together in the bloodstream, yet weak enough to release when the particle binds to cancer cells.

Zhang, an assistant professor in the School of Chemistry and Biochemistry, has learned to precisely control the size and magnetic properties of his nanoparticles through variations in chemistry and process conditions. His goal is a "recipe book" that researchers could use to produce magnetic nanoparticles with the specific properties needed for a variety of applications, such as drug delivery, enhancement agents for diagnostic tests and replacement of radioactive tracers.

"We are understanding the fundamental ways to control the properties of these particles, chemically manipulating the magnetic interactions at the atomic level," he explains. "We want to make the connection between these atomic-level interactions and the macroscopic behavior we want in these materials."

Zhang and his colleagues have also taken another critical step, demonstrating that antibodies attached to the surface of their nanoparticles maintain their bioactivity. In use, specific antibodies on the nanoparticles would recognize and bind to receptors on the cancer cells, like a key in a lock. Once bound to the target cells, the particles would release their load of chemotherapy drugs.

Using surface chemistry techniques, Zhang has also camouflaged the surface of his particles to help them get past the body's immune system.

For more information, contact Rina Tannenbaum, School of Materials Science and Engineering, Georgia Tech, Atlanta, GA 30332-0245. (Telephone: 404-385-1235) (E-mail: rina.tannenbaum@mse.gatech.edu);    or John Zhang, School of Chemistry and Biochemistry, Georgia Tech, Atlanta, GA 30332-0400. (Telephone: 404-894-6368) (E-mail: john.zhang@chemistry.gatech.edu)