Department of Electrical Engineering and Computer Science, ‡Department of Biological Engineering, §Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, MA 02139, United States.
Anal Chem. 2013 Dec 17;85(24):11695-9. doi: 10.1021/ac402169x. Epub 2013 Nov 25.
In this paper, we evaluate the strategy of using self-assembled microbeads to build a robust and tunable membrane for free-flow zone electrophoresis in a PDMS microfluidic chip. To fabricate a porous membrane as a salt bridge for free-flow zone electrophoresis, we used silica or polystyrene microbeads between 3-6 μm in diameter and packed them inside a microchannel. After complete evaporation, we infiltrated the porous microbead structure with a positively or negatively charged hydrogel to modify its surface charge polarity. Using this device, we demonstrated binary sorting (separation of positive and negative species at a given pH) of peptides and dyes in standard buffer systems without using sheath flows. The sample loss during sorting could be minimized by using ion selectivity of hydrogel-infiltrated microbead membranes. Our fabrication method enables building a robust membrane for pressure-driven free-flow zone electrophoresis with tunable pore size as well as surface charge polarity.
在本文中，我们评估了使用自组装微球构建用于 PDMS 微流控芯片中自由流区电泳的稳健且可调谐膜的策略。为了制造用作自由流区电泳盐桥的多孔膜，我们使用直径为 3-6μm 的二氧化硅或聚苯乙烯微球，并将其填充在微通道内。完全蒸发后，我们用带正电荷或负电荷的水凝胶渗透多孔微球结构，以改变其表面电荷极性。使用该装置，我们在没有使用鞘流的情况下，在标准缓冲体系中对肽和染料进行了二元分拣（在给定 pH 值下分离正、负离子）。通过利用水凝胶渗透微球膜的离子选择性，可以将分拣过程中的样品损失最小化。我们的制造方法能够构建用于压力驱动的自由流区电泳的稳健膜，其孔径以及表面电荷极性均可调。
