CO2-leakage-driven diffusiophoresis causes spontaneous accumulation of charged materials in channel flow
CO2-leakage-driven diffusiophoresis causes spontaneous accumulation of charged materials in channel flow
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CO2 泄漏驱动的扩散电泳导致带电材料在通道流中自发积累
DOI：
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发表时间：
2020
影响因子：
11.1
通讯作者：
H. Stone
中科院分区：
文献类型：
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作者：
Suin Shim;H. Stone
颗粒负载流在生理和诊断系统中无处不在，通常颗粒（如胶体颗粒、细胞、大分子等）悬浮在水相中时获得非零的净表面电荷。聚二甲基硅氧烷（PDMS）是近二十年来微流体制造中最常用的材料。它的高透气性是公认的，但气体泄漏对带电粒子运动的可能影响尚未认识到。通过系统的实验和模型计算，我们证明了通过PDMS的初始（早期）气体泄漏可以通过扩散电泳在共同通道流动中产生电荷依赖的颗粒积累，并表明这种现象可以应用于浓缩和收集蛋白质。我们发现了一种现象，即通道流动的开始会产生意想不到的、带电的胶体颗粒积聚，这种现象发生在具有透气性壁的普通流动配置中，但没有任何安装的气源。带正电的（胺改性聚苯乙烯；a-PS）或带负电的（聚苯乙烯；PS）颗粒的水悬浮液流入聚二甲基硅氧烷（PDMS）通道，在流动开始后2至4分钟产生电荷依赖性积累。我们在各种条件下进行了系统的实验，并考虑了通道壁的渗透性和二氧化碳驱动的扩散泳动，进行了模型计算。我们证明了这种粒子的自发输运是由通道和环境之间的压力差引起的气体通过可渗透壁的泄漏驱动的。由于液体压力较高，在流动中形成向外的气体通量。我们还在霍乱弧菌的细菌悬浮液中观察到这种现象，其中荧光蛋白（mKO；单体Kusabira Orange）和细菌细胞在通道流动中表现出电荷依赖性分离。这样的实验观察表明，带电粒子在水悬浮液中的扩散电泳可以通过气体通过可渗透壁泄漏来实现，而在液相中没有任何预先施加的离子浓度梯度。我们的发现将有助于解决涉及颗粒和气体渗透壁的芯片上实验中意想不到的挑战和偏见，并有助于理解生理系统中自然存在的类似结构，如肺毛细血管。我们还展示了潜在的应用，如浓缩和收集等电点以下的蛋白质。
Significance Particle-laden flow is ubiquitous in physiological and diagnostic systems, where usually the particles (e.g., colloidal particles, cells, macromolecules, etc.) gain a nonzero net surface charge when suspended in an aqueous phase. Polydimethylsiloxane (PDMS) has been the most popular material used for microfluidic fabrications for the past two decades. Its high gas permeability is well appreciated, but the possible influence of gas leakage on the motion of charged particles has not been recognized. By systematic experiments and model calculations, we demonstrate that initial (early time) gas leakage through PDMS can create a charge-dependent accumulation of particles in common channel flows by diffusiophoresis and show that the phenomenon can be applied to concentrating and collecting proteins. We identify a phenomenon where the onset of channel flow creates an unexpected, charge-dependent accumulation of colloidal particles, which occurs in a common-flow configuration with gas-permeable walls, but in the absence of any installed source of gas. An aqueous suspension of either positively charged (amine-modified polystyrene; a-PS) or negatively charged (polystyrene; PS) particles that flowed into a polydimethylsiloxane (PDMS) channel created charge-dependent accumulation 2 to 4 min after the onset of flow. We unravel the phenomenon with systematic experiments under various conditions and model calculations considering permeability of the channel walls and CO2-driven diffusiophoresis. We demonstrate that such spontaneous transport of particles is driven by the gas leakage through permeable walls, which is induced by the pressure difference between the channel and the ambient. Since the liquid pressure is higher, an outward flux of gas forms in the flow. We also observe the phenomenon in a bacterial suspension of Vibrio cholerae, where the fluorescent protein (mKO; monomeric Kusabira Orange) and bacterial cells show charge-dependent separation in a channel flow. Such experimental observations show that diffusiophoresis of charged particles in an aqueous suspension can be achieved by having gas leakage through permeable walls, without any preimposed ion-concentration gradient in the liquid phase. Our findings will help resolve unexpected challenges and biases in on-chip experiments involving particles and gas-permeable walls and help understand similar configurations that naturally exist in physiological systems, such as pulmonary capillaries. We also demonstrate potential applications, such as concentrating and collecting proteins below the isoelectric point.
影响因子：
19.7
作者：
Kiessling F;Mertens ME;Grimm J;Lammers T
通讯作者：
Lammers T
影响因子：
38.3
作者：
通讯作者：
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