Silver embedded nanostars for SERS with internal reference (SENSIR)†
We report the synthesis of a unique hybrid nanoplatform consisting of silver-embedded gold nanostars that entraps a reference dye between the gold and silver surfaces, providing an internal reference signal for quantitative surface-enhanced Raman scattering (SERS) analysis without the need for aggregation. The unique geometry of the nanostar provides SERS enhancement in a non-aggregated state for analytes on the exterior surface of the particle. When an equivalent structure was created using gold nanospheres as the core, no SERS signal from the analyte was observed until aggregation was induced by the addition of salt. Rhodamine 6G (Rh6G) was used as a model analyte to demonstrate this proof of concept. The use of the internal standard to reduce SERS signal variability was demonstrated in a highly scattering medium and at various particle concentrations, to simulate conditions that may be encountered with real-world samples. This novel, internal reference containing nanostructure will aid quantitative SERS analysis in complex media.