Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots-particles that are a few nanometers in size-will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body. They can also be programmed to bond only to a certain type of cell-a particular cancer cell, for example.Doctors can then use a camera and look for the colored particles, which will help them determine where cancer cells are growing in a person's body.