HORIZONTAL SOLVENT-FREE LIPID BIMOLECULAR MEMBRANES WITH 2-SIDED ACCESS CAN BE FORMED AND FACILITATE ION-CHANNEL RECONSTITUTION

We present here an easily used method and apparatus for formation of h orizontal 'solvent-free' lipid bilayer membranes affording two-sided a ccess. These horizontal bilayers allow direct delivery of submicrolite r volumes of samples onto the membrane upper surface increasing the ef ficacy of reconstitution by several orders of magnitude, as demonstrat ed using Staphylococcus aureus alpha-toxin. Also, they permit creation of locally high and transient transbilayer osmotic gradients to initi ate fusion of ion-channel containing liposomes with planar membrane, w hich, following fusion, leaves the membrane and channel in essentially symmetric bathing solutions. This method is especially advantageous f or cases where thickness of the membrane, absence of hydrocarbon solve nt, or presence of differing lipid compositions in the two monolayers is critical.