The First Silver-Based Plasmonic Nanomaterial for Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy with Magnetic Properties

Abstract

Nanostructures made of magnetic cores (from Fe3O4 ) with attached silver plasmonic nanos-tructures were covered with a very thin layer of silica. The (Fe3O4@Ag)@SiO2 magnetic–plasmonic nanomaterial can be manipulated using a magnetic field. For example, one can easily form ho-mogeneous layers from this nanomaterial using a very simple procedure: deposition of a layer of a sol of such a nanostructure and evaporation of the solvent after placing the sample in a strong magnetic field. Due to the rapid magnetic immobilization of the magnetic–plasmonic nanomaterial on the investigated surface, no coffee-ring effect occurs during the evaporation of the solvent. In this contribution, we report the first example of a magnetic, silver-based plasmonic nanomaterial for shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Nanoresonators based on silver plasmonic nanostructures locally enhance the intensity of the exciting electromagnetic radiation in a significantly broader frequency range than the previously used magnetic SHINERS nanores-onators with gold plasmonic nanostructures. Example applications where the resulting nanomaterial was used for the SHINERS investigation of a monolayer of mercaptobenzoic acid chemisorbed on platinum, and for a standard SERS determination of dopamine, are also presented.