Non-invasive measurement techniques for measuring properties of droplet interfacebilayers

Abstract

Phospholipids and membrane proteins are two of the fundamental building blocks of cellmembranes in living organisms. These molecules are amphipathic and form organizedstructures in water. Synthetic membranes made of phospholipids called bilayer lipidmembranes have been used to study the characteristics of a cell membrane using both solidsupport and liquid support systems. A droplet interface bilayer is a liquid support systemwhere a bilayer is formed at the interface of two water droplets in an oil bathwhere the water droplets are covered with a monolayer of phospholipids. Certainmembrane proteins self-insert into the bilayer formed and can change the ionconduction across the bilayer. Electrodes inserted into the droplets can induceion flow, but cause a discontinuity in the monolayer surrounding the droplets.This paper shows that to circumvent this discontinuity, electrodes can be usedexternally to stimulate ion flow within the droplets. The electrodes are coatedwith a hydrogel that is in turn coated with a monolayer of phospholipids. Uponcontact with a droplet coated with phospholipids, a bilayer forms, providing ameans for induced ion flow in the droplet without piercing through the monolayercoating. Proteins can insert in this connection and influence the induced ion flow.