Mostafa A. El-Sayed of Georgia Tech, USA reports on Applications of Gold Nanoparticles. New fields such as optoelectronics, sensors, nanocatalysis, nanomotors and nano-medicine use the new exciting properties of gold and silver nanoparticles with scattering radiative properties. They posses the coherent localized surface plasmon oscillation when resonant radiation interacts with their free electrons in the conduction band. This results in strong electro-dynamic surface fields that extends beyond the surface and enhance their absorption and as well as of any system that falls within this field. The strong scattering properties can be used in imaging and sensitive detection of cancer cells . The strong absorbed photon energy is rapidly converted into heat that can be used in rapid light modulation; the rapid sublimation of its atoms and its propulsion and flying away with jet velocities or it can heat and melts attached cancer cells leading to their destruction and thus used in cancer therapy.