Nanotechnology aids in cancer fight.

• Position: Laser Therapy

A noninvasive laser therapy that destroys cancer cells but leaves healthy ones unharmed has been developed by scientists at Stanford (Calif.) University.

"One of the longstanding problems in medicine is how to cure cancer without harming normal body tissue," says Hongjie Dai, associate professor of chemistry. "Standard chemotherapy destroys cancer cells and normal cells alike. That's why patients often lose their hair and suffer numerous other side effects. For us, the Holy Grail would be finding a way to selectively kill cancer cells and not damage healthy ones."

For the experiment, Dai and his colleagues used a basic tool of nanotechnology--carbon nanotubes, synthetic rods that are only half the width of a DNA molecule. Thousands of nanotubes easily could fit inside a typical cell.

"An interesting property of carbon nanotubes is that they absorb near-infrared light waves, which are slightly longer than visible rays of light and pass harmlessly through our cells," Dai explains. However, shine a beam of near-infrared light on a carbon nanotube, and the results are dramatic. Electrons in the nanotube become excited and begin releasing excess energy in the form of heat. In the experiment, researchers discovered that, if they placed a solution of carbon nanotubes under a near-infrared laser beam, it would heat up to about 158[degrees]F in two minutes. When nanotubes...