Improvement of the quality of self assembled bilayer lipid membranes by using a negative potential

Self-assembled lipid bilayer membranes (s-BLMs) on the tip of Teflon-coated silver electrodes were formed according to the T. Tien method. Their formation process and properties were investigated by capacitance and voltage current cycle measurements. The stability of the membranes was improved and defects were eliminated through the application of a negative dc potential during formation. Cyclic current-voltage measurements were applied to probe membrane integrity, by using an electrolyte interacting with the silver electrode. Oxidation and reduction peaks were observed for non defect-free membranes. These peaks were caused by oxidation of the silver electrode tip and their occurrence was a very sensitive means of measuring membrane integrity. The membrane was a barrier for the ion transport from the electrolyte solution to the electrode surface, and thus defect-free membranes inhibited the appearance of the peaks. With the s-BLMs produced by the described method, binding of ions and proteins to the membrane could be measured repetitively and reproducibly through changes in the system capacitance and the shape of the cyclovoltammogram. The presence of divalent ions lead to a specific increase in total system capacitance of membranes from charged lipids. Protein binding was measured as a decrease of the capacitance, in accordance with the thickness increase of the total membrane after binding. The facility of production and the sensitivity of the aforementioned substances could make the s-BLMs, produced by the described method, a valuable system to be developed in the field of biosensing. (C) 2001 Elsevier Science B.V. All rights reserved.