Measurement of Light Attenuation in Phantom Tissue Embedded with Gold Nanoshells

Abstract

Light attenuation in phantom tissue embedded with gold nanoshells is measured using a photospectrometer with an integrated sphere system. Gold nanoshells are synthesized and a paste is made by mixing them with agar (or phantom tissue); from which slab samples of different nanoshell concentrations and thicknesses are prepared. Light attenuation is measured as a function of light exciting frequencies, nanoshell concentrations and tissue thickness. The nanoshell particle concentrations are determined by matching the Mie solution for a single nanoshell with the measured attenuation coefficient at the local surface plasma resonance frequency. For the range of the concentrations studied, light attenuation is linearly dependent on the nanoshell concentration, and thus the rule of independent scattering/absorption is observed. The frequency of exciting light strongly affects light attenuation in a nanoshell-populated medium, with the largest attenuation occurring at the local surface plasma resonance frequency of the nanoshells, which is consistent with theoretical predictions. For the measured samples of phantom tissue populated with nanoshells, the optical thickness is about ~8 mm.