Controlling Size and Morphology in Hybrid Core@Shell and Core@Shell@Satellite Nanostructures for Sensing by Surface-Enhanced Raman Scattering

Abstract

Here, we report the fabrication of several hybrid bimetallic core@shell and core@shell@satellite colloidal nanostructures. These nanosystems are structured as spherical and non-spherical metallic and bimetallic cores encapsulated by a thermo-responsive N-isopropylacrylamide (pNIPAM) shell (core@shell) with incorporated Ag satellites (core@shell@satellite). The metallic and bimetallic non-spherical cores include Au nanotriangles and bimetallic AuAg nanocubes, respectively. By using different amounts of AgNO3 during chemical reduction and through the seed-mediated approach, we are able to modify the Ag satellite sizes. We performed thermo-responsive surface-enhanced Raman spectroscopy (SERS) investigations for core@shell and core@shell@satellite nanosystems as a function of temperature, with improved SERS responses for the core@shell@satellite structure.