Particle Deformation and Concentration Polarization in Electroosmotic Transport of Hydrogels through Pores
Particle Deformation and Concentration Polarization in Electroosmotic Transport of Hydrogels through Pores
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DOI：
10.1021/nn400774e
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发表时间：
2013-04-01
期刊：
影响因子：
17.1
通讯作者：
Siwy, Zuzanna S.
中科院分区：
文献类型：
--
作者：
Pevarnik, Matthew;Schiel, Matthew;Siwy, Zuzanna S.
在这篇文章中，我们报告了可变形的检测，水凝胶颗粒的连续脉冲技术，使用聚合物膜中的单个孔。水凝胶通过电渗穿过孔，并导致形成电阻脉冲的特征形状，表明颗粒经历了脱水和变形。这些效应通过沿孔隙轴沿着的非均匀压力分布来解释，该非均匀压力分布由耦合的Poisson-Nemst-Planck和Navier-Stokes方程来模拟。局部压降由电渗流体流动引起。我们的实验还揭示了浓度极化在水凝胶检测中的重要性。由于水凝胶颗粒的负电荷以及分支的低密度结构，颗粒中的离子浓度显著高于本体中的离子浓度。因此，当跨膜施加电场时，可以在颗粒附近产生耗尽区，观察到电流的瞬时下降。我们使用开口在200和1600 nm之间的孔的实验表明，浓度极化主导了水凝胶对宽于450 nm的孔的检测。这些结果对于所有涉及分子、颗粒和细胞通过带电孔壁运输的研究都具有重要意义。发展的不均匀的压力分布可能会影响被输送物质的形状。浓差极化改变了电阻脉冲的解释;观察到的电流变化不一定只反映颗粒大小，还反映了在颗粒附近形成的耗尽区的大小。
In this article, we report detection of deformable, hydrogel particles by the resistive-pulse technique using single pores in a polymer film. The hydrogels pass through the pores by electroosmosis and cause formation of a characteristic shape of resistive pulses indicating the particles underwent dehydration and deformation. These effects were explained via a non-homogeneous pressure distribution along the pore axis modeled by the coupled Poisson-Nemst-Planck and Navier-Stokes equations. The local pressure drops are induced by the electroosmotic fluid flow. Our experiments also revealed the importance of concentration polarization in the detection of hydrogels. Due to the negative charges as well as branched, low-density structure of the hydrogel particles, the concentration of ions in the particles is significantly higher than in the bulk. As a result, when an electric field is applied across the membrane, a depletion zone can be created in the vicinity of the particle observed as a transient drop of the current. Our experiments using pores with openings between 200 and 1600 nm indicated the concentration polarization dominated the hydrogels' detection of pores wider than 450 nm. The results are of importance for all studies that involve transport of molecules, particles, and cells through pores with charged walls. The developed inhomogeneous pressure distribution can potentially influence the shape of the transported species. The concentration polarization changes the Interpretation of the resistive pulses; the observed current change does not necessarily reflect only the particle size but also the size of the depletion zone that is formed in the particle vicinity.