(722f) Large Area Model Biomembranes (LAMBs) to Understand Membrane Mechanics, Structure, and Function

The development of model cellular membranes is crucial for fundamental investigations of biological phenomena, ranging from antimicrobial peptide pore formation and biomolecule transport to bilayer elasticity and lipid raft formation. In this talk, a versatile platform to generate free-standing, planar, phospholipid bilayers with millimeter scale areas will be introduced. The technique relies on an adapted thin-film balance apparatus allowing for the dynamic control of the nucleation and growth of a planar black lipid membrane in the center of an orifice surrounded by microfluidic channels. A unique advantage in this system for the study of membrane mechanics is control of the membrane tension in a planar geometry, which is demonstrated by measuring the elasticity modulus of bilayers with varying composition. Simultaneous fluorescence microscopy enables monitoring the lateral heterogeneity in ternary lipid mixtures undergoing phase separation. In particular, the the effect of interdigitation on phase separation in mixtures containing hybrid lipids (â??linactantsâ?) is shown by comparing bilayer, â??inverseâ? bilayer, and monolayer experiments. Independent control of the solution conditions on either side of the bilayer allows for characterizing the response of biological membranes to external stimuli, such as the introduction of antimicrobial peptides. In this realm, the destabilizing effect of Magainin II due to pore formation and altered membrane tension on bilayers reconstituted from bacterial cell lipids is analyzed. Together, the results demonstrate a new paradigm for studying the mechanics, structure, and function of model biomembranes.