PDF(Pubmed)
Abstract：
Quorum sensing enables unicellular organisms to probe their population density and perform behavior that exclusively occurs above a critical density. Quorum sensing is established in emulsion droplet swarms that float at a water surface and cluster above a critical density. The design involves competition between 1) a surface tension gradient that is generated upon release of a surfactant from the oil droplets, and thereby drives their mutual repulsion, and 2) the release of a surfactant precursor from the droplets, that forms a strong imine surfactant which suppresses the surface tension gradient and thereby causes droplet clustering upon capillary (Cheerios) attraction. The production of the imine-surfactant depends on the population density of the droplets releasing the precursor so that the clustering only occurs above a critical population density. The pH-dependence of the imine-surfactant formation is exploited to trigger quorum sensing upon a base stimulus: dynamic droplet swarms are generated that cluster and spread upon spatiotemporally varying acid and base conditions. Next, the clustering of two droplet subpopulations is coupled to a chemical reaction that generates a fluorescent signal. It is foreseen that quorum sensing enables control mechanisms in droplet-based systems that display collective responses in contexts of, e.g., sensing, optics, or dynamically controlled droplet-reactors.
摘要：
群体感应使单细胞生物体能够探测其种群密度并执行仅在临界密度以上发生的行为。在漂浮在水面并聚集在临界密度以上的乳液液滴群中建立了群体感应。该设计涉及1）表面张力梯度之间的竞争，该表面张力梯度是在从油滴中释放表面活性剂时产生的，从而驱使他们相互排斥，和2)从液滴中释放表面活性剂前体，形成强亚胺表面活性剂，抑制表面张力梯度，从而导致液滴聚集在毛细管（Cheerios）吸引力上。亚胺-表面活性剂的产生取决于释放前体的液滴的种群密度,使得聚集仅在临界种群密度以上发生。亚胺-表面活性剂形成的pH依赖性被用来在碱刺激下触发群体感应：产生动态液滴群，这些液滴群在时空变化的酸和碱条件下聚集并扩散。接下来,两个液滴亚群的聚集与产生荧光信号的化学反应耦合。可以预见，群体感应使基于液滴的系统中的控制机制能够在以下情况下显示集体响应：例如，传感,光学,或动态控制的液滴反应器。
