Droplet Interface Bilayer as Cell Membrane Mimics: Water Permeability Studies

Abstract

The process of water permeation across lipid membranes has significant implications for cellular physiology and homeostasis, and its study may lead to a greater understanding of the relationship between the structure of lipid bilayer and the role that lipid structure plays in water permeation. We have created a biomimetic artificial membrane, through contact of water droplets in an oil solution containing lipids. Using optical microscopy, we have measured water transport between droplets, as water moves from one droplet to another due to concentration difference. This was assessed as a function of lipid content, structure, and additives, such as cholesterol, which is an essential component of cell membrane. Our results show that cholesterol can increase the activation energy of water permeability several-fold, depending upon the structure of the lipid that makes up the bilayer, thus shedding light on how this singular sterol is vital to control of water movement. We demonstrate that the droplet interface bilayer can be employed as a convenient model membrane to rapidly explore subtle structural effects on bilayer water permeability.