Photolipid Bilayer Permeability is Controlled by Transient Pore Formation

Abstract

Controlling the release or uptake of (bio-) molecules and drugs from liposomes is critically important for a range of applications in bioengineering, synthetic biology, and drug delivery. In this paper, we report how the reversible photoswitching of synthetic lipid bilayer membranes made from azobenzene-containing phosphatidylcholine (<i>azo</i>-<b>PC</b>) molecules (photolipids) leads to increased membrane permeability. We show that cell-sized, giant unilamellar vesicles (GUVs) prepared from photolipids display leakage of fluorescent dyes after irradiation with UV-A and visible light. Langmuir-Blodgett and patch-clamp measurements show that the permeability is the result of transient pore formation. By comparing the <i>trans</i>-to-<i>cis</i> and <i>cis</i>-to-<i>trans</i> isomerization process, we find that this pore formation is the result of area fluctuations and a change of the area cross-section between both photolipid isomers.