Effect of Hydration on Plasmonic Coupling of Bioconjugated Gold Nanoparticles Immobilized on a Gold Film Probed by Surface- Enhanced Raman Spectroscopy

摘要

Gold nanoparticle (AuNP)?Au film constructs were prepared using antibody?antigen interactions or a small organic crosslinker to systematically control the gap between the AuNP and Au film. Surface-enhanced Raman spectroscopy (SERS), scanning electron micrsocopy (SEM), and atomic force microscopy (AFM) were used to characterize each construct and elucidate structure?activity relationships. Interestingly, plasmonic coupling and SERS intensity were reversibly modulated with wetting/drying cycles for the protein immobilized AuNP, and this effect was attributed to changes in protein size with hydration state. This work provides insight into fundamental limitations of AuNP-enabled SERS bioassays and will facilitate rational design of novel biospecific ligands that maximize SERS sensitivity.