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Bright Surface‐Enhanced Raman Scattering with Fluorescence Quenching from Silica Encapsulated J‐Aggregate Coated Gold Nanoparticles
Author(s) -
Walters Christopher M.,
Pao Caroline,
Gag Brandon P.,
Zamecnik Colin R.,
Walker Gilbert C.
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201705381
Subject(s) - materials science , raman scattering , raman spectroscopy , fluorescence , nanoparticle , colloidal gold , nanotechnology , analytical chemistry (journal) , photochemistry , optics , chemistry , organic chemistry , physics
Plexitonic nanoparticles offer variable optical properties through tunable excitations, in addition to electric field enhancements that far exceed molecular resonators. This study demonstrates a way to design an ultrabright surface‐enhanced Raman spectroscopy (SERS) signal while simultaneously quenching the fluorescence background through silica encapsulation of the semiconductor–metal composite nanoparticles. Using a multistep approach, a J‐aggregate‐forming organic dye is assembled on the surface of gold nanoparticles using a cationic linker. Excitonic resonance of the J‐aggregate–metal system shows an enhanced SERS signal at an appropriate excitation wavelength. Further encapsulation of the decorated particles in silica shows a significant reduction in the fluorescence signal of the Raman spectra (5× reduction) and an increase in Raman scattering (7× enhancement) when compared to phospholipid encapsulation. This reduction in fluorescence is important for maximizing the useful SERS enhancement from the particle, which shows a signal increase on the order of 10 4 times greater than J‐aggregated dye in solution and 24 times greater than Oxonica S421 SERS tag. The silica layer also serves to promote colloidal stability. The combination of reduced fluorescence background, enhanced SERS intensity, and temporal stability makes these particles highly distinguishable with potential to enable high‐throughput applications such as SERS flow cytometry.