Bailey Matthew R, Pentecost Amber M, Selimovic Asmira, Martin R Scott, Schultz Zachary D
†University of Notre Dame, Department of Chemistry and Biochemistry, Notre Dame, Indiana 46556, United States.
‡Saint Louis University, Department of Chemistry, St. Louis, Missouri 63103, United States.
Anal Chem. 2015 Apr 21;87(8):4347-55. doi: 10.1021/acs.analchem.5b00075. Epub 2015 Apr 7.
The combination of hydrodynamic focusing with embedded capillaries in a microfluidic device is shown to enable both surface enhanced Raman scattering (SERS) and electrochemical characterization of analytes at nanomolar concentrations in flow. The approach utilizes a versatile polystyrene device that contains an encapsulated microelectrode and fluidic tubing, which is shown to enable straightforward hydrodynamic focusing onto the electrode surface to improve detection. A polydimethyslsiloxane (PDMS) microchannel positioned over both the embedded tubing and SERS active electrode (aligned ∼200 μm from each other) generates a sheath flow that confines the analyte molecules eluting from the embedded tubing over the SERS electrode, increasing the interaction between the Riboflavin (vitamin B2) and the SERS active electrode. The microfluidic device was characterized using finite element simulations, amperometry, and Raman experiments. This device shows a SERS and amperometric detection limit near 1 and 100 nM, respectively. This combination of SERS and amperometry in a single device provides an improved method to identify and quantify electroactive analytes over either technique independently.
微流控装置中流体动力学聚焦与嵌入式毛细管的结合被证明能够在流动状态下对纳摩尔浓度的分析物进行表面增强拉曼散射（SERS）和电化学表征。该方法利用了一种通用的聚苯乙烯装置，该装置包含一个封装的微电极和流体管道，结果表明它能够直接在电极表面实现流体动力学聚焦，从而改善检测效果。位于嵌入式管道和SERS活性电极上方（彼此对齐约200μm）的聚二甲基硅氧烷（PDMS）微通道产生鞘流，将从嵌入式管道中洗脱的分析物分子限制在SERS电极上方，增加了核黄素（维生素B2）与SERS活性电极之间的相互作用。使用有限元模拟、安培法和拉曼实验对该微流控装置进行了表征。该装置的SERS检测限和安培检测限分别接近1 nM和100 nM。在单个装置中结合SERS和安培法提供了一种比单独使用任何一种技术都更好的方法来识别和定量电活性分析物。
