Abstract：
Developments in droplet microfluidics have facilitated an era of high-throughput, sensitive single-cell, or single-molecule measurements capable of tackling the heterogeneity present in biological systems. Relying on single emulsion (SE) compartments, droplet assays achieve absolute quantification of nucleic acids, massively parallel single-cell profiling, and more. Double emulsions (DEs) have seen recent interest for their potential to build upon SE techniques. DEs are compatible with flow cytometry enabling high-throughput multi-parameter drop screening and eliminate content mixing due to coalescence during lengthy workflows. Despite these strengths, DEs lack important technical functions that exist in SEs such as methods for adding reagents to droplets on demand. Consequently, DEs cannot be used for multistep workflows which has limited their adoption in assay development. Here, strategies to enable reagent addition and other active manipulations on DEs are reported by converting DE inputs to SEs on chip. After conversion, drops are manipulated using existing SE techniques, including reagent addition, before reforming a DE at the outlet. Device designs and operation conditions achieving drop-by-drop reagent addition to DEs are identified and used as part of a multi-step aptamer screening assay performed entirely in DE drops. This work enables the further development of multistep DE droplet assays.
摘要：
液滴微流体的发展促进了高通量的时代，敏感的单细胞，或单分子测量能够解决生物系统中存在的异质性。依靠单一乳液(SE)隔室，液滴测定实现核酸的绝对定量，大规模并行单细胞分析，还有更多.双重乳液（DE）最近对其在SE技术上的潜力产生了兴趣。DE与流式细胞术兼容，可实现高通量多参数液滴筛选，并消除由于冗长工作流程中的聚结而导致的内容物混合。尽管有这些优势,DE缺乏SE中存在的重要技术功能，例如按需将试剂添加到液滴中的方法。因此,DE不能用于多步骤工作流，这限制了它们在测定开发中的采用。这里,通过将DE输入转换为芯片上的SE来报告使试剂添加和对DE进行其他主动操作的策略。转换后,使用现有的SE技术操纵液滴，包括试剂添加，在出口处进行DE改革之前。确定了实现向DE中逐滴添加试剂的装置设计和操作条件,并将其用作完全在DE液滴中进行的多步骤适体筛选测定的一部分。这项工作使多步骤DE液滴测定的进一步发展。
