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Marangoni Convection Assisted Single Molecule Detection with Nanojet Surface Enhanced Raman Spectroscopy
ACS Sensors ( IF 8.2 ) Pub Date : 2017-07-20 00:00:00 , DOI: 10.1021/acssensors.7b00427
Te-Wei Chang 1 , Xinhao Wang 2 , Amirreza Mahigir 3 , Georgios Veronis 3 , Gang Logan Liu 2 , Manas Ranjan Gartia 4
Affiliation  

Many single-molecule (SM) label-free techniques such as scanning probe microscopies (SPM) and magnetic force spectroscopies (MFS) provide high resolution surface topography information, but lack chemical information. Typical surface enhanced Raman spectroscopy (SERS) systems provide chemical information on the analytes, but lack spatial resolution. In addition, a challenge in SERS sensors is to bring analytes into the so-called “hot spots” (locations where the enhancement of electromagnetic field amplitude is larger than 103). Previously described methods of fluid transport around hot spots like thermophoresis, thermodiffusion/Soret effect, and electrothermoplasmonic flow are either too weak or detrimental in bringing new molecules to hot spots. Herein, we combined the resonant plasmonic enhancement and photonic nanojet enhancemnet of local electric field on nonplanar SERS structures, to construct a stable, high-resolution, and below diffraction limit platform for single molecule label-free detection. In addition, we utilize Marangoni convection (mass transfer due to surface tension gradient) to bring new analytes into the hotspot. An enhancement factor of ∼3.6 × 1010 was obtained in the proposed system. Rhodamine-6G (R6G) detection of up to a concentration of 10–12 M, an improvement of two orders of magnitude, was achieved using the nanojet effect. The proposed system could provide a simple, high throughput SERS system for single molecule analysis at high spatial resolution.

中文翻译:

纳米喷射表面增强拉曼光谱的Marangoni对流辅助单分子检测

许多无单分子(SM)标签的技术,例如扫描探针显微镜(SPM)和磁力光谱(MFS),都可提供高分辨率的表面形貌信息,但缺乏化学信息。典型的表面增强拉曼光谱(SERS)系统可提供有关分析物的化学信息,但缺乏空间分辨率。此外,SERS传感器面临的挑战是将分析物带入所谓的“热点”(电磁场振幅增强幅度大于10 3的位置)。)。先前描述的围绕热点的流体运输方法(例如热泳,热扩散/索雷特效应和电热等离子体流)太弱或不利于将新分子带入热点。在本文中,我们结合了非平面SERS结构上的局部电场的共振等离子体增强和光子纳米喷射增强mnet,以构建稳定,高分辨率和低于衍射极限的单分子无标记检测平台。此外,我们利用Marangoni对流(由于表面张力梯度而引起的质量转移)将新的分析物带入了热点。在提出的系统中获得了约3.6×10 10的增强因子。罗丹明6G(R6G)的检测浓度最高为10 –12利用纳米射流效应,M提高了两个数量级。提出的系统可以为高空间分辨率的单分子分析提供简单,高通量的SERS系统。
更新日期:2017-07-21
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