(657c) Analysis and Large-Scale Synthesis of Bimetallic Nanocube Substrate for Surface Enhanced Raman Scattering

Analysis
and Large-Scale Synthesis of Bimetallic Nanocube Substrate for Surface Enhanced
Raman Scattering

Joshua Weatherston¹, Nolan Worstell¹,
Hung-Jen Wu¹

¹Dept. Chemical Engineering, Texas A&M
University, USA

Surface
Enhanced Raman Scattering (SERS) is a highly sensitive spectroscopic technique capable
of identifying surface-adsorbed chemical species at extremely low
concentrations, down to single molecule detections. The low detection threshold
and the ?fingerprint? nature of this vibrational spectroscopic method, as well
as its compatibility with equipment found in many research and diagnostic labs,
make SERS an ideal candidate for multiplexed biomolecule detection. SERS is a
consequence of the large electric field enhancement present near nanostructured
surfaces; as such, its signal is dependent on the morphology and dielectric
properties of the substrate and the analyte's proximity to the substrate. To
create a suitable substrate for high-throughput SERS measurements, highly monodisperse
plasmonic silver nanocubes were synthesized and coated with several atomic
layers of gold in a large-scale batch synthesis. The theoretical SERS
enhancement of Ag@Au core-shell nanocubes, pure Ag nanocubes, hollow Au cages, and
other similar structures were calculated using finite element method (FEM),
which predicted large enhancement factors. The FEM computation was confirmed by
acquiring Raman spectra of the nanocubes functionalized with Raman-active
organic dyes. It was found that the Ag@Au nanocubes showed large enhancement
factors. Compared with pure silver nanocubes, the gold coated substrate showed
greater Raman enhancement, increased resistance to particle degradation, and
better compatibility with biological analytes. The multiplexing capabilities of
this system were successfully demonstrated by detecting the co-adsorption of
multiple dye species on the nanocube surface, including labeled and unlabeled
peptide sequences. Furthermore, this platform was used to analyze the enzymatic
digestion kinetics of peptide-functionalized nanocubes.

Submitting
author: Joshua Weatherston, Dept. Chemical Engineering, Texas A&M
University, College Station, TX 77843, USA, Tel: +1-361-232-3982; Email:
jdub@tamu.edu