The effect of substrate metal on 2-aminoethanethiol and nanoparticle enhanced surface plasmon resonance imaging

Using nanoparticles, it is possible under certain experimental conditions to considerably enhance the sensitivity of a conventional surface plasmon resonance (SPR) device. In this report, the mechanism of this enhancement was examined after substrates, to which Au or Ag nanoparticles were adsorbed were prepared. In addition, the experimental factors that are crucial to the performance of such a nanoparticle-based SPR device were examined. Among these factors, the surface plasmon-supporting metal substrate plays a major role. This was demonstrated by comparing experimental SPR data for An and Ag substrates. In both cases, 10 nm diameter An particles or 30 nm Ag particles were attached to the substrate metal via a monolayer of 2-aminoethanethiol. The morphology of the substrates were examined by an atomic force microscopy, and the observation is explained in terms of competitive effects of propagating surface plasmons in the substrate metal and localized surface plasmons in the Au or Ag. (C) 2001 Published by Elsevier Science B.V.