Liquid-state quantitative SERS analyzer on self-ordered metal liquid-like plasmonic arrays

Liquid interfacial plasmonic platform is emerging for new sensors, catalysis, and tunable optical devices, but also promises an alternative for practical applications of surface-enhanced Raman spectroscopy (SERS). Here we show that vigorous mixing of chloroform with citrate-capped gold nanorod sols triggers the rapid self-assembly of three-dimensional plasmonic arrays at the chloroform/water ( O / W ) interface and produces a self-healing metal liquid-like brilliant golden droplet. The O phase itself generates stable SERS fingerprints and is a good homogeneous internal standard for quantitative analysis. This platform presents reversible O / W encasing in a common cuvette determined just by surface wettability of the container. Both O -in- W and W -in- O platforms exhibit excellent SERS sensitivity and reproducibility for different analytes by the use of a portable Raman device. It paves the way toward a practical and quantitative liquid-state SERS analyzer, likened to a simple UV–Vis spectrometer, that is far superior to typical solid substrate-based or nanoparticle sol-based analysis.