Effect of a polymer cushion on the electrical properties and stability of surface-supported lipid bilayers

A robust biomimetic cell membrane platform is critical for mechanistic studies of membrane protein channels. While polymer cushions are believed to facilitate the incorporation of membrane proteins in such a platform, a systematic characterization and optimization of such cushions is rarely performed. Here, we examine the influence of a polymer cushion on the electrical properties of supported 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) bilayers produced via a Langmuir-Blodgett deposition/vesicle fusion assembly process on single-crystal silicon. We show that the resistance of DPhPC bilayers is maximized at the calculated crossover concentration of the polymer (5.9 mol % PEG-lipids). Additionally, these bilayers are sufficiently stable to allow impedance analyses to be performed for nearly 3 weeks. These studies reveal the optimal PEG concentration that yields electrically robust bilayers and demonstrate the utility of the platform for future studies of membrane protein channels and membrane active peptides.