College of Food and Biological Engineering, Engineering Research Center of Bio-process, Ministry of Education , Hefei University of Technology , Hefei , Anhui 230009 , China.
Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Life Sciences, and Aptamer Engineering Center of Hunan Province , Hunan University , Changsha , Hunan 410082 , China.
Anal Chem. 2019 Feb 5;91(3):2288-2295. doi: 10.1021/acs.analchem.8b04893. Epub 2019 Jan 18.
Liquid-state interfacial plasmonic systems are emerging as an alternative for the quantitation and practicability of the surface-enhanced Raman scattering (SERS) technique in analytical science, especially for complex liquid-phase systems. Here we show a general strategy for the three-dimensional (3D) self-assembly of gold nanoparticle (GNP) arrays on a spherical oil-water (O-W) interface, denoted as a plasmonic metal liquid (PML). The PML has excellent self-healing and shape-adaptive features; it can be transferred into containers of any shape; and it presents fast, quantitative, and multiplex SERS capability. Accurate control of nanoparticle density (PD) on the 3D interface enables tunable SERS strength. In situ synchrotron radiation small angle X-ray scattering (SR-SAXS) provides evidence that the interfacial PD is quantifiable and can be precisely regulated in the range of 24-216 particles/μm, which produces optimizable Raman enhancement. The strongest SERS signal is achieved at 167 particles/μm with GNP diameters of approximately 64 nm. In particular, the O phase acts not only as the assembly media for spherical PML arrays but also as the extracting agent for targets with different natures in complex media. Moreover, the O phase with continuous-phase features generates inherent and sharp SERS fingerprints and provides an effective internal standard (IS) for calibrating the fluctuation of samples and measuring conditions. By virtue of the triple roles of the O phase, the PML platform exhibits excellent mechanical stability, detection sensitivity, and signal reproducibility. This study demonstrates the concept of a fast and quantitative liquid-state SERS platform in common cuvettes on a portable Raman device that is as simple as a spectrophotometer.
液态界面等离子体系统作为分析科学中表面增强拉曼散射（SERS）技术的定量和实用性的替代方案，特别是对于复杂的液相系统，正逐渐兴起。在这里，我们展示了一种在球形油水（O-W）界面上自组装金纳米颗粒（GNP）阵列的通用策略，称为等离子体金属液体（PML）。PML 具有出色的自修复和形状自适应特性；它可以转移到任何形状的容器中；并且具有快速、定量和多重 SERS 能力。在 3D 界面上准确控制纳米颗粒密度（PD）可实现可调谐的 SERS 强度。同步辐射小角 X 射线散射（SR-SAXS）的原位测量结果表明，界面 PD 是可量化的，并且可以在 24-216 个粒子/μm 的范围内进行精确调节，从而产生可优化的拉曼增强。在 PD 为 167 个粒子/μm 时，获得最强的 SERS 信号，GNP 直径约为 64nm。特别是 O 相不仅作为球形 PML 阵列的组装介质，而且作为复杂介质中不同性质目标物的萃取剂。此外，具有连续相特征的 O 相产生固有且尖锐的 SERS 指纹，并为校准样品和测量条件的波动提供有效的内部标准（IS）。由于 O 相的三重作用，PML 平台表现出优异的机械稳定性、检测灵敏度和信号重现性。这项研究展示了在便携式拉曼设备上的普通比色皿中快速定量液态 SERS 平台的概念，其操作简单如分光光度计。
