Quantitative SERS Using the Sequestration of Small Molecules Inside Precise Plasmonic Nanoconstructs

ABSTRACT: We show how the macrocyclic host, cucurbit[8]uril (CB[8]), creates precise subnanometer junc-tions between gold nanoparticles while its cavity simulta-neously traps small molecules; this enables their reproducible surface-enhanced Raman spectroscopy (SERS) detection. Explicit shifts in the SERS frequencies of CB[8] on complexation with guest molecules provides a direct strategy for absolute quantification of a range of molecules down to 10−11 M levels. This provides a new analytical paradigm for quantitative SERS of small molecules