Metallic gold is more precious on the nanometer size scale: Some properties and applications of gold nanoparticles of different shapes in nanophotonics, nanomotors, nanomedicine and nanobiology

PHYS 150

Mostafa A. El-Sayed, melsayed@chemistry.gatech.edu, Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400
New fields such as optoelectronics, sensors, nanocatalysis, nanomotors and nano-medicine use the new exciting properties of gold and silver nanoparticles. 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 scattering Radiative properties 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. This localized heating of the gold nanoparticles can lead to: its melting, its coherent lattice oscillation 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. We further found that the interaction between the strong Plasmonic fields of two nanoparticles shifts their absorption wavelength according to a Universal Scaling law that can be used in determining the distance between sites in Biological systems (a new biological ruler). These properties and example of their applications will be discussed.