Sombrero-shaped plasmonic nanoparticles with molecular-level sensitivity and multifunctionality

ACS Nano. 2011 Aug 23;5(8):6449-57. doi: 10.1021/nn201649n. Epub 2011 Jul 12.

Abstract

We demonstrate top-down synthesis of monodisperse plasmonic nanoparticles designed to contain internal Raman hot spots. Our Raman-active nanoparticles are fabricated using nanoimprint lithography and thin-film deposition and are composed of novel internal structures with sublithographic dimensions: a disk-shaped Ag core, a Petri-dish-shaped SiO(2) base whose inner surface is coated with Ag film, and a sub-10 nm scale circular gap between the core and the base. Confocal Raman measurements and electromagnetic simulations show that Raman hot spots appear at the inside perimeter of individual nanoparticles and serve as the source of a 1000-fold improvement of minimum molecular detection level that enables detection of signals from a few molecules near hot spots. A multimodality version of these nanoparticles, which includes the functionality offered by magnetic multilayers, is also demonstrated. These results illustrate the potential of direct fabrication for creating exotic monodisperse nanoparticles, which combine engineered internal nanostructures and multilayer composite materials, for use in nanoparticle-based molecular imaging and detection.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Magnetic Phenomena
  • Nanoparticles / chemistry*
  • Nanotechnology / methods*
  • Rhodamines / chemistry
  • Silicon Dioxide / chemistry

Substances

  • Rhodamines
  • rhodamine 6G
  • Silicon Dioxide