Fighting cancer with quantum dots

The bits of semiconducting material that are lately brightening the colors on television screens hold a much greater promise-that they will extend lives. These tiny crystals are far too small to be seen with the naked eye, measuring just one ten-thousandth the width of a human hair, which is one reason they're called quantum dots. When you shine a suitable light on such a dot, it becomes luminous, emitting a very pure color that is determined by its size.