ELECTROSTRICTION OF LIPID BILAYERS ON A SOLID SUPPORT - INFLUENCE OF HYDROCARBON SOLVENT AND DC VOLTAGE

A new method for forming bilayer lipid membranes on solid substrates (s-BLMs) was recently developed by Tien and Salamon. They showed that s-BLMs could be used in practical applications for the development of molecular electronic devices and biosensors. Using the electrostriction method, we have studied the elasticity modulus perpendicular to the membrane plane (E(perpendicular-to)), dynamic viscosity coefficient (eta), electrical capacitance (C) and membrane potential (DELTAPHI(m)) of s-BLMs formed from soybean phosphatidylcholine as a function of length of hydrocarbon chain of the solvent, cholesterol concentration and d.c. voltage applied to the membrane. We found that E(perpendicular-to) of s-BLMs is one order of magnitude less than that for conventional BLMs formed in the aqueous phase. Unlike that for BLMs, E(perpendicular-to) of s-BLMs did not depend on the length of hydrocarbon chain of the solvent or the cholesterol concentration in the lipid solution. The parameters E(perpendicular-to), eta and C of s-BLMs showed a complicated behaviour as a function of the amplitude, polarity and rate of change of applied d.c. voltage. In addition, s-BLMs are considerably more stable than BLMs: their electrical breakdown voltage can reach 1.5 V. Significant differences between s-BLMs and BLMs are very probably due to differences in bilayer structure. A model of s-BLM structure and compressibility explaining these differences is presented.