Enlarge the biologic coating-induced absorbance enhancement of Au-Ag bimetallic nanoshells by tuning the metal composition

Spectrochim Acta A Mol Biomol Spectrosc. 2018 Jan 15:189:571-577. doi: 10.1016/j.saa.2017.08.064. Epub 2017 Sep 1.

Abstract

Surface plasmon resonance (SPR) absorption properties of biologic layer-coated Au-Ag core-shell nanoparticle have been studied theoretically. By comparing with pure Au and Ag nanoparticles, the absorption peak intensity of Au-Ag bimetallic nanoparticle is more dependent on the dielectric coating, and the longer wavelength peak corresponding to the Au-Ag interface is more sensitive to the coating thickness. As the Au-Ag composition ratio is increased, the dielectric coating-dependent peak intensity change is always non-monotonous, and the critical Au-Ag composition ratio corresponding to the greatest peak intensity increase could be further tuned by changing the dielectric constant of the coated dielectric layer. The physical mechanism of the non-monotonous sensitivity change has been attributed to the Au-Ag composition ratio-dependent separation and overlap of the two SPR peaks from Au-Ag interface and outer Ag surface. These results indicate that the plasmonic absorption intensity of Au-Ag core-shell nanoparticle could be used in refractive index sensing and biologic detection.

Keywords: Computer modelling and simulation; Nanostructures; Optical properties; Surface plasmon resonance (SPR).

MeSH terms

  • Absorption, Physicochemical*
  • Coated Materials, Biocompatible / chemistry*
  • Electricity
  • Gold / chemistry*
  • Nanoshells / chemistry*
  • Silver / chemistry*
  • Surface Plasmon Resonance

Substances

  • Coated Materials, Biocompatible
  • Silver
  • Gold