Cutting out cancer

LITTLE ROCK, Ark. -- An Arkansas doctor is trying to find a safe and efficient way to target cancerous cells using flecks of gold that are only nanometers wide. It could set a new standard for breast cancer therapy.

Dr. Vladimir Zharov, a biomedical engineer and director of laser research at the University of Arkansas for Medical Sciences, won a $106,500 grant from the U.S. Department of Defense Breast Cancer Research Program, to study the treatment concept.

The concept is still unproven, but preliminary tests have shown the gold "nanoparticles" could interact with laser radiation to destroy only the targeted cells, without collateral damage to healthy cells, Zharov said.

Several teams of researchers around the world are looking at similar concepts. Gerald Diebold, professor of chemistry at Brown University, said chemists and medical researchers are scrambling to find ways to improve on the current X-ray and ultrasound technology used to diagnose tumors.

"A mammogram is a mess of lines. ... It's so hard to see any gradations until the tumor is already metastasized," he said. "But we've known about gold's absorption for a long time and I think we're making very nice progress."

Once attached to tumor cells, the gold absorbs laser light far more thoroughly than anything else, which makes it ideal for diagnostic imaging of small, hard-to-detect tumors. And the laser's destructive power also could be harnessed to attack cells with gold marks on them without so much as cutting into the breast.

Alexander Oraevsky of Fairway Medical Technologies in Houston, who patented an elongated gold particle that appears to absorb laser light best, said scientists are still years away from figuring out the best way to deliver the gold markings to tiny clusters of tumor cells, without hurting a patient.

"This is a very hot area, and nanotechnology in association with lasers is very big," Oraevsky said. "But the major question remains: Can the nanoparticles be delivered specifically to cancer in a human body sufficiently and efficiently?"

Zharov, who came to Little Rock from Moscow in 2000, said he thinks he can create a smarter delivery system through his research. He and Dmitri Lapotko of A.V. Luikov Heat and Mass Transfer Institute in Minsk, Belarus, spent years in Russia studying how gold could be used to create clearer diagnostic images.

But when the laser beam was strengthened, Zharov realized the nanoparticles could go "from markers to killers." He calls his concept "magic gold atomic bullets."

Zharov said laser light interacts with gold particles and creates heat and sound waves that make the gold explode, and he expects that the mini-blasts will destroy only the marked tumor cells, not the healthy breast tissue cells.

He said he will use the federal grant over the next year for in-vitro tests on rats to pinpoint ideal temperatures, to find the best ways to deliver the gold to tumor cells and to ensure that healthy cells are never affected. To this point, tests have been limited to dead samples under a microscope.

Zharov's pursuit is hardly novel. The concept of absorption and light scattering inside a spherical object is nearly 100 years old, said Oraevsky, a former University of Texas biomedical engineer. He worked for the last decade using lasers as "optical tweezers" to safely remove malignant tissue. He credits his colleagues at Rice University, Naomi J. Halas and Jennifer West, with designing nanoparticles for treatment of tumor cells.

The problem will be in receiving approval for human tests, Diebold said. Current research will determine how long that will take. Last year, Halas and West received a multimillion-dollar award from the U.S. Army Medical Research and Materiel Command, and Oraevsky received a $1 million grant from the National Institutes of Health.