99 BioeLxtrochemistry and Bioenergetics, 31(1993) 99-111 Elsevier Sequoia S.A., Lausanne JEC BB zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 01591 Electrostriction of lipid bilayers on a solid support. Influence of hydrocarbon solvent and d.c. voltage T. Hianik, J. Dlugopolsky and M. Gyepessova Department of Biophysics ana’ Chemical Physics, Comenius Uniuersity, Mlynska dolina FI, 842 15 Bratislava (Slovak Republic) (Received 11 July 1992; in revised form 30 November 1992) Abstract 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,), dynamic viscosity coefficient (71, electrical capacitance (C) and membrane potential (A@,,,,) 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 I of s-BLMs is one order of magnitude less than that for conventional BLMs formed in the aqueous phase. Unlike that for BLMs, E I 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 I, -q and C of s-BLMs showed a complicafed 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. INTRODUCTION Bilayer lipid membranes (BLMs) are widely used in the study of various problems of membrane biophysics. Recently, new opportunities for using such systems in the development of biosensors and electronic devices have appeared. Practical applications, however, require considerable stability and a long life. Sufficient portability is also important. Conventional methods of BLM formation by spreading a lipid solution over a small hole in the wall separating two aqueous compartments of a Teflon cup [ll do not meet these prerequisites. A simple and 0302-4598/93/$06.00 0 1993 - Elsevier Sequoia S.A. All rights reserved