Department of Chemistry, Saint Louis University, St. Louis, MO, USA.
Electrophoresis. 2013 Jul;34(14):2092-100. doi: 10.1002/elps.201300163.
In this paper, we present two new methodologies of improving the performance of microchip-based electrochemical detection in microfluidic devices. The first part describes the fabrication and characterization of epoxy-embedded gold microelectrode arrays that are evenly spaced and easily modified. Electrodepositions using a gold plating solution can be performed on the electrodes to result in a 3D pillar array that, when used with microchip-based flow injection analysis, leads to an eightfold increase in signal (when compared to a single electrode), with the LOD for catechol being 4 nM. For detecting analytically challenging molecules such as nitric oxide (NO), platinization of electrodes is commonly used to increase the sensitivity. It is shown here that microchip devices containing either the pillar arrays or more traditional glassy carbon electrodes can be modified with platinum black (Pt-black) for NO detection. In the case of using glassy carbon electrodes for NO detection, integration of the resulting platinized electrode with microchip-based flow analysis resulted in a ten times signal increase relative to use of a bare glassy carbon electrode. In addition, it is demonstrated that these electrodes can be coated with Nafion to impart selectivity toward NO over interfering species such as nitrite. The LOD for NO when using the Pt-black /Nafion-coated glassy carbon electrode was 9 nM. These electrodes can also be embedded in a polystyrene substrate, with the applicability of these sensitive and selective electrodes being demonstrated by monitoring the adenosine triphosphate-mediated release of NO from endothelial cells immobilized in a microfluidic network without any adhesion factor.
本文提出了两种提高微流控芯片电化学检测性能的新方法。第一部分描述了均匀间隔且易于修饰的环氧嵌入金微电极阵列的制造和表征。使用镀金溶液在电极上进行电沉积可得到 3D 柱阵列，当与微流控芯片流动注射分析结合使用时，与单个电极相比，信号增加了八倍，邻苯二酚的检测限为 4 nM。对于检测具有挑战性的分析物，如一氧化氮 (NO)，通常使用电极的镀铂来提高灵敏度。这里表明，包含柱阵列或更传统的玻碳电极的微芯片设备可以用铂黑 (Pt-black) 进行修饰以用于 NO 检测。在使用玻碳电极进行 NO 检测的情况下，与使用裸玻碳电极相比，将所得的镀铂电极与微流控芯片流动分析集成可使信号增加十倍。此外，还证明可以将这些电极用 Nafion 涂层，赋予其对 NO 相对于干扰物质（如亚硝酸盐）的选择性。使用 Pt-black/Nafion 涂覆的玻碳电极检测 NO 的检测限为 9 nM。这些电极也可以嵌入聚苯乙烯基质中，通过监测固定在微流控网络中的内皮细胞中介导的三磷酸腺苷释放的 NO，证明了这些敏感和选择性电极的适用性，而无需任何粘附因子。
