Electrochemistry of Biomimetic Membranes - Applications of Electrochemistry and Nanotechnology in Biology and Medicine - page 192

Figure 13. (A) Schematic picture of the cross-section of a black lipid membrane
obtained by the painting method, with the Plateau-Gibbs border. (B-D) Preparation
of the Montal-Mueller bilayer lipid membrane by raising the solution level on the
left hand side of the aperture and, then, on its right hand side.
these BLMs has not been established, but it is clearly important to
be able to form solvent-free planar bilayers.
A method for forming bilayers from lipid monolayers that
eliminates solvent was developed by Montal and Mueller. 98 . Two
polytetrafluoroethylene troughs containing an aqueous solution are
separated by a thin (6.5-25 Pm) septum through which a hole, 0.1-
0.5 mm in diameter, is punched above the solution level. A lipid
monolayer is spread from a pentane or hexane solution on each
aqueous solution. After the solvent has evaporated, the water level
is raised above the aperture first in one trough, and then in the oth-
er, bringing the alkyl chains of the monolayers into apposition (see
Fig. 13 ). The Montal-Mueller technique is a particularly signifi-
cant achievement because asymmetric bilayers can be formed 99
and proteins can be incorporated by first introducing them into the
lipid monolayers. 100 The differential capacitance of this solvent-
free BLM amounts to 0.8÷0.9 PF cm -2 , 98 and it is higher than that,
about 0.3÷0.4 PF cm -2 , of a BLM obtained by the painting meth-
od. 101 Evidently, the presence of organic solvent in the latter BLM
decreases its differential capacitance.