Electrostriction and membrane potential of lipid bilayers on a metal support

Using the electrostriction method we have studied the elasticity modulus perpendicular to the membrane plane, E(perpendicular to), and electrical capacitance, C, of supported bilayer lipid membranes formed on the freshly cut tip of Teflon-coated silver or platimum wires (s-BLM), or on thin platinum layers sputtered on a glass surface (sl-BLM), as a function of d.c. voltage applied to the membrane. The measured value of E(perpendicular to) was found to change considerably with increasing d.c. voltage, the rate of change of voltage, and on successive cycles of changing the voltage after membrane formation. The measured values of E(perpendicular to) for sl-BLM were about one order of magnitude higher than for s-BLM. This could be due to either the different degree of contact between the wire and its coating or the roughness of the support. Evidence is presented that edge effects could be involved in the observed phenomenon. Possibilities for further study of these phenomena are discussed.