Laboratoire de Photonique et de Nanostructures, CNRS-UPR 20, 91460 Marcoussis, France.
Anal Chem. 2013 Aug 20;85(16):7948-56. doi: 10.1021/ac4016159. Epub 2013 Aug 8.
We investigate the preconcentration profiles of a fluorescein and bovine serum albumin derivatized with this fluorescent tag in a microfluidic chip bearing a nanoslit. A new preconcentration method in which a hydrodynamic pressure is added to both electroosmotic and electrophoretic contributions is proposed to monitor the location of the preconcentration frontline. A simple predictive model of this pressure-assisted electropreconcentration is proposed for the evolution of the flow profile along this micro/nano/microfluidic structure. We show with a small analyte such as fluorescein that the additional hydrostatic pressure mode enables to stabilize the concentration polarization (CP) effect, resulting in better control of the cathodic focusing (CF) peak. For BSA (bovine serum albumin), we exhibit that the variation of the hydrodynamic pressure can have an even more drastic effect on the preconcentration. We show that, depending on this hydrodynamic pressure, the preconcentration can be chosen, either in the cathodic side or in the anodic one. For the first time, we prove here that both anodic focusing (AF) and cathodic focusing (CF) regimes can be reached in the same structures. These results also open new routes for the detection and the quantification of low abundance biomarkers.
我们研究了在带有纳米狭缝的微流控芯片中，荧光素和牛血清白蛋白与这种荧光标记物衍生化后的预浓缩分布。提出了一种新的预浓缩方法，即在电渗流和电泳贡献的基础上增加流体静压力，以监测预浓缩前沿的位置。针对这种压力辅助电预浓缩，提出了一种简单的预测模型，用于预测沿微/纳/微流控结构的流动剖面的演变。我们用小的分析物如荧光素证明，附加的静压模式可以稳定浓度极化（CP）效应，从而更好地控制阴极聚焦（CF）峰。对于牛血清白蛋白（BSA），我们表明，流体静压力的变化甚至可以对预浓缩产生更剧烈的影响。我们表明，根据这个流体静压力，可以选择在阴极侧或阳极侧进行预浓缩。这是首次在同一结构中证明可以同时达到阳极聚焦（AF）和阴极聚焦（CF）两种模式。这些结果还为检测和定量低丰度生物标志物开辟了新途径。
