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 m olecular electronic devices and biosensors. Using the electrostriction method, we have studied the elasticity modulus perpendicular to the m embrane plane (E(perpendicular-to)), dynamic viscosity coefficient (et a), electrical capacitance (C) and membrane potential (DELTAPHI(m)) of s-BLMs formed from soybean phosphatidylcholine as a function of lengt h 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 B LMs 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 th e solvent or the cholesterol concentration in the lipid solution. The parameters E(perpendicular-to), eta and C of s-BLMs showed a complicat ed behaviour as a function of the amplitude, polarity and rate of chan ge 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 co mpressibility explaining these differences is presented.