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

Abstract

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.

Surface‐enhanced Raman spectroscopy for on‐site analysis: A review of recent developments

“…To solve this problem, Tianet al prepared a 3D liquid SERS substrate with a reversible oil phase/water phase (O/W) encasing strategy for on-site analysis by SERS ( Figure 14). [121] In this study, cetyltrimethylammonium bromide (CTAB) was used as the capping agent to synthesize homogeneous GNRs, then Ci-GNR sol was obtained through a ligand methods. Chloroform was added into the…”

“…Internal standard (IS) calibrated methods have also been studied by several research groups to overcome the issues of on-site quantification, including intrinsic IS and embedded IS methods. [123][124][125] [121] with permission from the Royal Society of Chemistry. )…”

Recent advances in gold nanoparticles for biomedical applications: from hybrid structures to multi-functionality

“…In cases where rapid renal clearance is desirable, the NPs should be smaller than 10 nm, which is the effective cut-off size of the 47 (b) single crystal nanowire, 52 (c) chiral NPs, 31,45 (d) core-shell NPs, 27 (e) Janus NPs, 23 (f) alloyed NPs, 142,174 (g) plasmonic meta-molecules, 175 (h) DNA-origami templated assemblies, 25 (i) large-scale assemblies of NPs. 99,176 Adapted by permission from the corresponding references. Copyright American Chemical Society, Springer Nature, Wiley-VCH.…”

“…4c). 66,99 Such a system is now able to perform in vivo multiplexing (with animals) and paper-based SERS diagnosis of DNA and protein biomarkers, tumour cells, blood glucose, and bacterial pathogens, [100][101][102][103][104] potentially via a commercial smartphone (right panel of Fig. 4c).…”

“…66 The middle panel shows the SEM image of the self-assembled gold nanorods (inset: its photo in bulk). 99 Right panel shows a photo of an on-site SERS measurement using the smartphone-based Raman spectrometer. 105 (d) Multi-reflection spectra of plasmonic antennas revealing the signal deformation according to lipid membranes and protein molecules in the enhanced optical field (top panel).…”