School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China.
Anal Chem. 2011 Oct 15;83(20):8029-34. doi: 10.1021/ac2017458. Epub 2011 Sep 23.
A facile method is presented for achieving comprehensive two-dimensional droplet manipulations in closed microstructures consisting of microwell arrays and a straight microchannel. In this method, picoliter/nanoliter droplets with controllable sizes and numbers are sampled from nanoliter samples/reagents with almost 100% efficiency. Droplet motions are precisely controlled in the ±X-direction and ±Y-direction by managing hydrostatic pressure and magnetic repulsion, respectively. As a demonstration, a fluorescein-labeled droplet and a deionized droplet are successively generated and trapped in adjacent microwells. Then their positions are quickly exchanged without cross-contamination and fusion is implemented on-demand. After operations, hydrophobic ferrofluid can be completely replaced by mineral oil and droplets still remain in microwells safely. A typical fluorescence intensity-based assay is demonstrated: droplet arrays containing copper ion are diluted disproportionately first and then detected by addition of droplet arrays containing Calcein. With the ability of comprehensive two-dimensional droplet manipulations, this method could be used in various miniaturized biochemical analyses including requirements of multistep procedures and in situ monitoring.
一种简单的方法被提出，以实现包含微井阵列和直微通道的封闭微结构中的全面二维液滴操作。在这种方法中，皮升至纳升级别的液滴可以以几乎 100%的效率从纳升级别的样品/试剂中进行采样，并且具有可控的大小和数量。通过分别管理静压力和磁斥力，可以精确地控制液滴在±X 方向和±Y 方向上的运动。作为一个演示，成功地生成并捕获了一个荧光素标记的液滴和一个去离子液滴在相邻的微井中。然后，它们的位置可以快速交换而不会发生交叉污染，并且按需实现融合。操作后，疏水铁磁流体可以被完全替换为矿物油，并且液滴仍然安全地留在微井中。展示了一个基于典型荧光强度的分析：首先不成比例地稀释含有铜离子的液滴阵列，然后通过添加含有钙黄绿素的液滴阵列进行检测。通过全面的二维液滴操作能力，该方法可以用于各种小型化生物化学分析，包括多步程序的要求和原位监测。
