Concentration Enrichment, Separation, and Cation Exchange in Nanoliter-Scale Water-in-Oil Droplets
Concentration Enrichment, Separation, and Cation Exchange in Nanoliter-Scale Water-in-Oil Droplets
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DOI：
10.1021/jacs.9b13268
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发表时间：
2020-02-12
影响因子：
15
通讯作者：
Anand, Robbyn K.
中科院分区：
文献类型：
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作者：
Kim, Sungu;Ganapathysubramanian, Baskar;Anand, Robbyn K.
基于液滴的技术已经在化学上产生了深远的影响，因为它们能够在微小的液体体积中执行快速和大规模的平行反应。在许多应用中，需要浓缩以提高反应速度或分析的灵敏度；但液滴内浓缩仍然具有挑战性。在这里，我们将电动浓差极化与液滴微流体相结合来实现液滴内的分离。这一结果意义重大，因为液滴中任何带电物种的浓度都可以得到浓缩，而且该方法可以很容易地整合到现有的液滴工作流程中。此外，我们还表明，这种电动浓缩是快速的，在秒的数量级上，并且是稳健的，发生在广泛的参数空间上。我们进一步演示了液滴中两个阴离子荧光团的电动分离。这种能力加强了以液滴为模板合成具有梯度组成的颗粒，并开发了迁移率位移分析，这依赖于对标记有单一颜色荧光团的多个物种的区分。最后，通过使用钙结合染料作为指示剂，我们演示了液滴内的阳离子交换。这一液滴中阳离子交换的证明具有重要意义，因为它广泛适用于合成和生物检测策略。这些结果为具有变革性应用的新的先进液滴技术奠定了基础。
Droplet-based techniques have had a profound impact in chemistry, owing to their ability to perform rapid and massively parallel reactions in minute fluid volumes. In many applications, concentration enrichment is required to increase the speed of reactions or the sensitivity of assays; but in-droplet concentration enrichment remains challenging. Here, we interface electrokinetic concentration polarization with droplet microfluidics to accomplish in-droplet demixing. This result is significant because the concentration of any charged species in the droplet can be enriched and the approach can be readily integrated into existing droplet workflows. Further, we show that such electrokinetic enrichment is rapid, on the order of seconds, and is robust, occurring over a wide parametric space. We further demonstrate electrokinetic separation of two anionic fluorophores within the droplet. Such a capability potentiates the droplet-templated synthesis of particles with gradient composition and the development of mobility-shift assays, which rely on discrimination of multiple species tagged with a single color fluorophore. Finally, by using a calcium-binding dye as an indicator, we demonstrate in-droplet cation exchange. This demonstration of cation exchange in droplets is significant because of its broad applicability to strategies for synthesis and bioassays. These results lay the foundation for new advanced droplet techniques with transformative applications.