Vilnius University Institute of Biotechnology, Graiciuno 8, Vilnius LT-02241, Lithuania.
Lab Chip. 2012 Apr 24;12(10):1800-6. doi: 10.1039/c2lc40121e. Epub 2012 Mar 27.
We report a microfluidic approach, which allows selective and controlled 1 : 1, 2 : 1 or 3 : 1 droplet fusion. A surfactant-stabilized droplet with an interfacial surfactant coverage, Γ, of >98% will fuse spontaneously with a second droplet when Γ of the latter droplet is <16%. However, when Γ of the second droplet is ~66%, the two droplets will not fuse, unless they have previously been brought into contact for critical time τ. Therefore, controlling the number of droplets in contact for time τ allows precise control over the number of fused droplets. We have demonstrated efficient (proportion of droplets coalesced p(c) = 1.0, n > 1000) and selective 1 : 1, 2 : 1 or 3 : 1 droplet fusion (proportion of correctly fused droplets p(s) > 0.99, n > 1000). Coalescence in this regime is induced by hydrodynamic flow causing interface separation and is efficient at different Ca numbers and using different dispersed phases, continuous phases and surfactants. However, when Γ of the second droplet is ~96% coalescence is no longer observed. Droplet-based microfluidic systems, in which each droplet functions as an independent microreactor, are proving a promising tool for a wide range of ultrahigh-throughput applications in biology and chemistry. The addition of new reagents to pre-formed droplets is critical to many of these applications and we believe the system described here is a simple and flexible method to do so, as well as a new tool to study interfacial stability phenomena.
我们报告了一种微流控方法,该方法允许选择性和控制性地进行 1:1、2:1 或 3:1 的液滴融合。当界面活性剂覆盖度 Γ 大于 98%的活性剂稳定液滴与 Γ 小于 16%的第二个液滴融合时,会自发融合。然而,当第二个液滴的 Γ 约为 66%时,除非它们之前已经接触过临界时间 τ,否则两个液滴不会融合。因此,控制接触 τ 时间的液滴数量可以精确控制融合的液滴数量。我们已经证明了有效的(融合液滴的比例 p(c) = 1.0,n > 1000)和选择性的 1:1、2:1 或 3:1 液滴融合(正确融合的液滴比例 p(s) > 0.99,n > 1000)。在此区域,通过导致界面分离的流体动力学流动引起聚结,并且在不同的 Ca 数和使用不同的分散相、连续相和表面活性剂时都有效。然而,当第二个液滴的 Γ 约为 96%时,不再观察到聚结。基于液滴的微流控系统,其中每个液滴都作为独立的微反应器,正在成为生物学和化学中广泛的超高通量应用的有前途的工具。向预形成的液滴中添加新试剂对于许多这些应用至关重要,我们认为这里描述的系统是一种简单而灵活的方法,也是研究界面稳定性现象的新工具。