Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, China.
Anal Chem. 2011 Mar 15;83(6):2083-9. doi: 10.1021/ac1028775. Epub 2011 Feb 21.
The controllable extraction of the contents from an individual droplet is very important for the analysis and further processing of droplets. Most of the available methods lack the control and flexibility over the extraction of droplet contents. Here, we present a novel electrical-based method that can selectively break a droplet and extract its contents into aqueous buffer in a controllable manner on a microfluidic device. The device consisted of two layers, in which the top layer was modified to be hydrophobic for droplet generation and the bottom layer modified to be hydrophilic for maintaining aqueous buffer. A stable oil/water interface was formed at the intersection of the two layers where the oil and aqueous buffer met. When a droplet flew through the oil/water interface, a voltage was applied in the aqueous buffer. The generated electro-osmotic flow in the aqueous buffer and the electric field facilitated the breaking of the water/oil interface between the droplet and aqueous buffer, promoting the breaking of the droplet and a transient coalescence of the droplet with aqueous buffer. During the transient coalescence, droplet contents could be extracted into aqueous buffer. The amount of the droplet contents extracted into the aqueous buffer could be controlled by varying the strength of the electric field, and the droplet still existed and could be further processed after complete extraction of the droplet contents. This method could be used for droplet analysis and may provide a way to perform complex fluid handling in a droplet.
从单个液滴中可控地提取内容对于液滴的分析和进一步处理非常重要。大多数现有的方法在液滴内容物的提取方面缺乏控制和灵活性。在这里，我们提出了一种新颖的基于电的方法，可以在微流控设备上以可控的方式选择性地打破液滴并将其内容物提取到水性缓冲液中。该装置由两层组成，其中顶层被修饰为疏水性以用于液滴生成，而底层被修饰为亲水性以用于保持水性缓冲液。在两层的交汇处形成了一个稳定的油/水界面，油和水性缓冲液在该处相遇。当液滴穿过油/水界面时，在水性缓冲液中施加电压。在水性缓冲液中产生的电渗流和电场促进了液滴和水性缓冲液之间的油水界面的破裂，促进了液滴的破裂和液滴与水性缓冲液的瞬间聚结。在瞬态聚结期间，可以将液滴内容物提取到水性缓冲液中。通过改变电场的强度，可以控制提取到水性缓冲液中的液滴内容物的量，并且在完全提取液滴内容物后，液滴仍然存在并且可以进一步处理。该方法可用于液滴分析，并可能为在液滴中进行复杂的流体处理提供一种方法。
