Cancer researchers have long sought a "magic bullet" that selectively targets tumor cells for destruction. In an attempt to enlist nanotechnology in that search, a Rice University spinoff, Nanospectra Biosciences, has developed gold-coated glass nanoparticles capable of invading a tumor and -- when heated remotely -- killing it.

The dimensions of the particles are the key to their effectiveness. Nanospectra's particles measure 150 nanometers in diameter, which the company believes is the ideal size to permit passage through tumors' characteristically leaky blood vessels. The particles should thus accumulate in tumors more than in other tissues. When near-infrared light is directed at the tumor site, either from outside the body or from a light probe inserted into the body, the particles absorb the light and heat up. As a result, the tumors get hotter than surrounding tissue and die.