Physics

Biography

Biography: Ophelie Squillace

Abstract

Models for biological membranes are essential to address fundamental studies regarding membrane-membrane interaction, the functionality of proteins, the dynamics of ions through the membrane and its structure in itself. Maintaining the membrane hydrated, fluidic and close to the substrate without cumbersome chemistry can be a challenge. Here, we develop a new experimental approach where a single model phospholipid bilayer is kept fluid and partially tethered to a flat electrode. We proposed an original anchoring surface functionalization that is highly reactive to –OH terminated molecules. In this way we avoid complex organic chemistry and graft commercial Brij non-ionic surfactants chosen for: their appropriate hydrophilic chain length that forms an aqueous cushion for the membrane; their hydrophobic alkyl block that anchors the lipid bilayers by insertion in their core. In this way, we keep the membrane fluidity in full immersion and presence of salts. This method appears to be a simple and cheap way to prepare tethered membranes with tunable anchoring densities on various supporting materials. Using transparent electrodes (ultra-flat and thin metal layers on glass), we could check the membrane fluidity and lipids dynamics from fluorescence techniques (such as in-situ FRAP for measuring the lateral diffusion of inserted fluorescent lipids). The transparent electrodes are also designed for high-resolution structure investigation of the single membrane using x-ray, neutron and light scattering methods (microscopies, surface plasmon resonance, fluorescence). Tethering the bilayer on conducting substrates also open avenues for the use of cheap and easy to build membrane biochips for biotechnological applications.