Surface Interactions Stabilize Lipids with High Intrinsic Curvature in Bacteria-Mimicking Planar Lipid Bilayers

Supported lipid bilayers are key platforms for measuring membrane-implicated drug interactions, disease mechanisms, and biological processes. Bacterial model membranes are a particularly high-value target but present unique fabrication challenges due to the high intrinsic curvature of their constituent lipids, notably phosphatidylethanolamine (PE). Here, we report a fundamental role for headgroup chemistry in stabilizing lipids with high intrinsic curvature on flat solid surfaces and predictive guidelines for tuning the preparative lipid concentration depending on surface chemistry. Building on recent developments in solvent-exchange techniques, we fully automate the production of bilayers comprised of a biologically relevant ratio of PE and the anionic lipid phosphatidylglycerol (PG). Neutron reflectometry measurements are performed to compare the structure of these membranes with that of bilayers containing phosphatidylcholine, the benchmark lipid for supported lipid bilayers. Bilayers are characterized in terms of both completeness and bilayer-substrate distance, which is indicative of adsorption strength, on neutral oxide, acidic, and basic surfaces. Despite their high intrinsic curvature, bacterial model membranes are found to interact strongly with all surfaces. We attribute this surprising observation to hydrogen bonding with substrate surface moieties. These observations lead to a unified predictive model of the physicochemical forces of bilayer adhesion to solid surfaces, enabling a future of high-throughput production of custom bilayers for complex assays and drug discovery.