Optical properties of metal nanoparticles and nanoparticle aggregates important in biosensors

This article describes recent advances in electrodynamics theory that are being used to describe the extinction spectra of noble metal nanoparticles and of aggregates of nanoparticles. In one application we have extended the finite element discrete dipole approximation theory to the description of nonspherical metal particles, including the substrate on which they are sitting. In another application, we have developed a new dynamic effective medium approximation for the description of aggregates of spherical gold nanoparticles that are linked using DNA. (C) 2000 Elsevier Science B.V. All rights reserved.