Developing
highly sensitive and stable surface-enhanced Raman scattering
(SERS) probe systems is an actively pursued goal in sensors and diagnostics.
In this study, we present silica-coated core–satellite (CS@SiO2) plasmonic nanoparticle assembly structures that potentially
realize this goal. We assemble different-sized gold nanoparticles
into core–satellite (CS) configurations using dithiol molecular
linkers that also serve as SERS labels. Multiple hot spots in the
CS structure and narrow nanogaps in each hot spot produce a significantly
enhanced Raman scattering signal with an enhancement factor of ∼8
× 107. Various types of molecules can be inserted
into the nanogaps using the mixed self-assembled monolayers with alkanedithiol,
enabling multiplex detection. Silica encapsulation of the CS nanoassemblies
stabilizes the particles and makes it easy to modify the surface to
attach antibodies or DNAs. Many properties of the CS@SiO2, including a wide range of optical resonances, scalability using
multiple glass slides, long-term stability in ethanol, and single-particle-level
sensitivity, make the material an ideal SERS probe for sensitive and
multiplexed detection of diseases and viruses.