Surface-enhanced Raman scattering from plasmonic Ag-nanocube@Au-nanospheres core@satellites

Plasmonic core@satellites nanostructures comprising strongly coupled Au-nanoparticles as building blocks have drawn a lot of attention because of the optical application, e.g. surface-enhanced Raman scattering (SERS) based signal amplification. However, little has been reported on the core@satellites structures related to Ag-nanoparticles and the SERS enhancement from a singular core@satellites assembling. Here, we show the DNA assisted assembly of core@satellites, consisting of Ag-nanocube core and small Au-nanosphere satellites. For each core@satellites unit, an Ag-nanocube as a core is assembled with randomly distributed Au-nanospheres as satellites. In this way, abundant hot spots are formed at the sharp edged Ag-nanocube and the nanoscaled gaps between the Ag-nanocube core and the Au-nanosphere satellite. Raman measurements, atomic force microscope correlated Raman measurements and finite element modeling demonstrate that the Raman enhancement factor of the singular Ag-nanocube@Au-nanospheres core@satellites can be up to 3.4 × 108. The Ag-nanocube@Au-nanoparticles core@satellites with in-built electromagnetic hot-spots could be used as excellent SERS substrates for rapid ultrasensitive detection of organic pollutants in the environment. Copyright © 2016 John Wiley & Sons, Ltd.