Controlling Bilayer Curvature and Membrane Protein Density using Droplet Interface Bilayers

Abstract

A Droplet Interface Bilayer (DIB) forms when nanolitre aqueous droplets are contacted together in an oil solution in the presence of phospholipids: A lipid monolayer forms at each oil-water interface, and by bringing together two monolayers a bilayer is created.We have recently extended this methodology to modulate both two-dimensional protein concentration[1] and membrane curvature.Manipulation of the axial position of the droplet relative to a hydrogel substrate controls the size of the bilayer formed at the interface; this enables the surface density of integral membrane proteins to be controlled. We are able to modulate the surface density of integral membrane proteins over a range of 4 orders of magnitude within a timeframe of a few seconds. By imaging DIBs on curved substrates we have observed correlation of lipid domain formation with sites of intrinsic curvature. This technique provides a new method for dictating the curvature of artificial bilayers, enabling single molecule measurements on the role of curvature in membrane organization and function.[1] Gross LCM, Castell OK, Wallace MI. Nano Letters (2011) http://dx.doi.org/10.1021/nl201689v