Functional Bionetworks from Nanoliter Water Droplets

We form networks from aqueous droplets by submerging them in an oil/lipid mixture. When the
droplets are joined together, the lipid monolayers surrounding them combine at the interface to form a
robust lipid bilayer. Various protein channels and pores can incorporate into the droplet-interface bilayer
(DIB), and the application of a potential with electrodes embedded within the droplets allows ionic currents
to be driven across the interface and measured. By joining droplets in linear or branched geometries,
functional bionetworks can be created. Although the interfaces between neighboring droplets comprise
only single lipid bilayers, the structures of the networks are long-lived and robust. Indeed, a single droplet
can be “surgically” excised from a network and replaced with a new droplet without rupturing adjacent
DIBs. Networks of droplets can be powered with internal “biobatteries” that use ion gradients or the light-driven proton pump bacteriorhodopsin. Besides their interest as coupled protocells, the droplets can be
used as devices for ultrastable bilayer recording with greatly reduced electrolyte volume, which will permit
their use in rapid screening applications.

我们通过将水相液滴浸没于油脂混合溶液中，构建液滴网络。当液滴相互结合时，包裹液滴的脂质单分子层会在界面处聚合形成坚固稳定的脂质双分子层。多种蛋白质通道与孔道可嵌入液滴界面双分子层（droplet-interface bilayer, DIB）中；通过嵌入液滴内部的电极施加电势，可驱动离子电流跨界面流动并完成检测。通过将液滴排布为线性或分支几何结构，可构建功能性仿生网络。尽管相邻液滴间的界面仅由单层脂质双分子层构成，该网络结构仍具备优异的长效性与稳定性。实际上，可通过"外科手术式"操作从网络中切除单个液滴，并更换为新液滴，且不会破坏相邻的DIB。液滴网络可借助内置"生物电池"供能，这类生物电池可利用离子梯度，或是以光驱动质子泵菌视紫红质（bacteriorhodopsin）作为供能元件。除了作为耦合型原细胞具备研究价值外，这类液滴还可作为超稳定双分子层记录装置，大幅降低电解质体积，从而可应用于快速筛选场景。