Synthesis of Glass‐Coated SERS Nanoparticle Probes via SAMs with Terminal SiO2 Precursors

Abstract

Surface-enhanced Raman scattering (SERS) combines the benefits of vibrational Raman scattering with highest sensitivity, using nanostructures that can support localized plasmon resonances. [1‐4] The main application of SERS is the label-free detection of analytes. [5‐8] An alternative and more recent approach uses SERS as a readout method in bioanalytical applications: the selective detection of proteins and oligonucleotides is achieved by employing target-specific SERS nanoparticle probes. [7‐11] The central motivation for this strategy is the option to detect numerous target molecules within a single measurement (multiplexing). The basis of spectral multiplexing in SERS arises from the small linewidth of vibrational Raman bands compared with the significantly broader emission profiles of molecular fluorophores. [12,13] Further important advantages are quantification of target concentration and the extreme sensitivity of SERS, in particular SERRS (surface-enhanced resonance Raman scattering). [14,15] Additionally, the simultaneous excitation of spectrally distinct SERS nanoparticle probes requires only a single laser wavelength. Different designs for nanoparticle-based SERS probes (SERSlabels,SERSnanotags)areavailable,whichdifferinthe plasmonic nanostructure, the Raman reporter molecule, and the optional protective shell. [9,16‐18] Using a self-assembled monolayer(SAM)ofRamanreportermoleculesonthesurface of the nanoparticle has several advantages. [18‐22] Firstly,