Highly permeable silicon membranes for shear free chemotaxis and rapid cell labeling.
Highly permeable silicon membranes for shear free chemotaxis and rapid cell labeling.
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DOI：
10.1039/c4lc00326h
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发表时间：
2014-07-21
期刊：
影响因子：
6.1
通讯作者：
McGrath JL
中科院分区：
文献类型：
--
作者：
Chung HH;Chan CK;Khire TS;Marsh GA;Clark A Jr;Waugh RE;McGrath JL
微流体系统是细胞生物学研究的有力工具，因为它们能够精确地添加和去除小体积的溶质。然而，在使用微流体进行细胞培养中固有的流体力有时是不期望的。一个重要的例子是趋化系统，其中液体流动会产生明确且稳定的趋化梯度，但也会将细胞推向下游。在这里，我们展示了一个趋化系统，其中两个室是由分子薄（15 nm），透明，纳米多孔硅膜分开。一个腔室是携带流动产生的梯度的微流体通道，而另一个腔室是用于细胞观察的无剪切环境。分子薄膜对两个腔室之间的分子扩散有效地没有阻力，使它们成为在微流体系统中创建无流动腔室的理想元件。解释膜和腔室几何形状的分析和计算流动模型预测剪切减少超过五个数量级。通过观察细胞容纳室中纳米颗粒的纯扩散证实了这一预测，尽管在仅15 nm远的流动室中有高输入流量（Q = 10 µL min−1; vavg ~45 mm min−1）。使用全内反射荧光（TIRF）显微镜，我们表明，流动产生的分子梯度将通过膜进入静止的细胞室。最后，我们证明，我们的设备允许我们暴露迁移的中性粒细胞的趋化梯度或荧光标记，没有任何影响的流动。
Microfluidic systems are powerful tools for cell biology studies because they enable the precise addition and removal of solutes in small volumes. However, the fluid forces inherent in the use of microfluidics for cell cultures are sometimes undesirable. An important example is chemotaxis systems where fluid flow creates well-defined and steady chemotactic gradients but also pushes cells downstream. Here we demonstrate a chemotaxis system in which two chambers are separated by a molecularly thin (15 nm), transparent, and nanoporous silicon membrane. One chamber is a microfluidic channel that carries a flow-generated gradient while the other chamber is a shear-free environment for cell observation. The molecularly thin membranes provide effectively no resistance to molecular diffusion between the two chambers, making them ideal elements for creating flow-free chambers in microfluidic systems. Analytical and computational flow models that account for membrane and chamber geometry, predict shear reduction of more than five orders of magnitude. This prediction is confirmed by observing the pure diffusion of nanoparticles in the cell-hosting chamber despite high input flow (Q = 10 µL min−1; vavg ~45 mm min−1) in the flow chamber only 15 nm away. Using total internal reflection fluorescence (TIRF) microscopy, we show that a flow-generated molecular gradient will pass through the membrane into the quiescent cell chamber. Finally we demonstrate that our device allows us to expose migrating neutrophils to a chemotactic gradient or fluorescent label without any influence from flow.