Improved Monodispersity of Plasmonic Nanoantennas via Centrifugal Processing

Noble metal nanoparticle clusters underlie a variety of plasmonic devices and measurements including enhanced Raman spectroscopy (SERS). Because of the strong dependence of plasmonic properties on nanoparticle cluster aggregation state, the elimination, of SERS-active structures, and the refinement of the nanoparticle cluster population are critical to realizing uniform and reproducible structures for plasmonic nanoantenna applications such as SERS-based sensors. In this Letter, we report a centrifugal sorting technique for gold core/silica shell nanoparticles that host SERS reporter molecules at the gold/silica interface. The relatively massive nanoparticle clusters are sorted, by sedimentation coefficient via centrifugation in a high-viscosity density gradient medium iodixanol, which yields solutions that contain a of an aggregation state and a diminished monomer population transmission electron microscopy extinction spectroscopy and analysis of the nanoparticle sedimentation coefficient to be be predictably generalized to other nanoparticle systems.