Model Lipid Bilayer - Tethered Bilayer Lipid Membranes (t-BLM)

Tethered Bilayer Lipid Membranes (t-BLM)

The use of a tethered bilayer lipid membrane (t-BLM) further increases the stability of supported membranes by chemically anchoring the lipids to the solid substrate.

Gold can be used as a substrate because of its inert chemistry and thiolipids for covalent binding to the gold. Thiolipids are composed of lipid derivatives, extended at their polar head-groups by hydrophilic spacers which terminate in a thiol or disulphide group that forms a covalent bond with gold, forming self assembled monolayers (SAM).

The limitation of the intra-membrane mobility of supported lipid bilayers can be overcome by introducing half-membrane spanning tether lipids with benzyl disulphide (DPL) and synthetic archaea analogue full membrane spanning lipids with phytanoly chains to stabilize the structure and polyethyleneglycol units as a hydrophilic spacer. Bilayer formation is achieved by exposure of the lipid coated gold substrate to outer layer lipids either in an ethanol solution or in liposomes.

The advantage of this approach is that the because of the hydrophilic space of around 4 nm, the interaction with the substrate is minimal and the extra space allows the introduction of protein ion channels into the bilayer. Additionally the spacer layer creates an ionic reservoir that readily enables ac electrical impedance measurement across the bilayer.