Highly reproducible and sensitive surface-enhanced Raman scattering from colloidal plasmonic nanoparticlevia stabilization of hot spots in graphene oxide liquid crystal

Abstract

Although it is now well recognized that plasmonic gold/silver nanoparticle based aggregates having electromagnetic hot spots are responsible for high sensitivity in surface-enhanced Raman spectroscopy (SERS), the high yield and reproducible production of such nanostructures are challenging and limit their practical application. Here we show a graphene oxide (GO) based approach in generating stable electromagnetic hot spots with high yield from colloidal plasmonic nanoparticles that leads to highly reproducible, stable and sensitive SERS for a wide range of molecules with Raman enhancement factors between 10⁸ to 10¹¹. The liquid crystalline property of dispersed GO directs the Raman probe induced controlled aggregation of plasmonic particles, restricting those aggregates to small and discrete clusters and stabilizing those clusters for longer times—offering the Raman probe induced ‘turn on’ SERS with high sensitivity and reproducibility. The presented approach is broadly applicable to different types of colloidal plasmonic particles and a wide range of Raman probes and is ideal for SERS based reliable detection of analyte at ultralow concentration.