Controlling the Sensing Volume of Metal Nanosphere Molecular Sensors

Abstract

Noble metal nanoparticles and nanoshells support surface plasmons at optical frequencies. These resonances, known as localized surface plasmons (LSPs), are sensitive to the dielectric properties of the environment and, in particular, to the refractive index of the material close to the surface of the particle. This sensitivity can be exploited in molecular detection systems that use nanoparticles functionalized with receptors to (a) bind target molecules and (b) optically transduce the resulting change in the dielectric environment. Optimization of an optical nanoparticle sensor involves tailoring the particle to the target so as to maximize the sensitivity of spectroscopic features to the dielectric variation associated with binding of target molecules to the particle surface.