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Highly Dense and Accessible Nanogaps in Au–Ag Alloy Patterned Nanostructures for Surface-Enhanced Raman Spectroscopy Analysis
journal contribution
posted on 2020-05-22, 22:14 authored by Taeksu Lee, Soongeun Kwon, Jae-Jong LeeWell-tailored
metal nanostructure arrays possessing a large number
of small nanogaps have been highlighted because of their ability to
enhance optical and electrical properties. In addition, it has been
demonstrated that nanostructures with two or more elements present
significantly enhanced and synergistic properties compared to those
with a single element. However, the precise and reliable synthesis
of bimetallic nanostructures possessing multiple nanogaps with high
uniformity remains a major challenge. In this study, we propose the
fabrication of bimetallic nanostructure patterns with numerous uncovered
and external nanogaps. Silver dot arrays (SDAs) without organic capping
ligands were developed via nanoimprint lithography, and several deposited
Au–Ag alloy nanogranules were directly deposited on SDAs through
a fast galvanic replacement reaction, without adding any additional
reducing agents or capping molecules, to produce highly accessible
nanogaps. These nanogaps surrounded by two types of metal elements
demonstrated an excellent surface-enhanced Raman scattering (SERS)
enhancement factor of up to 1.09 × 109, and the highly
homogeneous SDAs led to high signal uniformity (relative standard
deviation < 6.5 ± 0.3%) as well as device-to-device reproducibility.
Finally, it was demonstrated that the synthesized substrates can be
used as ultrasensitive and reliable SERS-based pesticide (malachite
green) detection probes, down to a 10 fM concentration.
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Keywords
replacement reactionsurface-enhanced RamanAccessible Nanogapsnanogapdevice-to-device reproducibilitySilver dot arrayssignal uniformitySERS-based pesticideenhancement factorbimetallic nanostructures10 fM concentrationnanoimprint lithographySurface-Enhanced Raman Spectroscopy Analysis Well-tailored metal nanostructure arraysbimetallic nanostructure patternsmetal elementsSDAdetection probes
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