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 forma tion process and properties were investigated by capacitance and voltage cu rrent cycle measurements. The stability of the membranes was improved and d efects were eliminated through the application of a negative dc potential d uring formation. Cyclic current-voltage measurements were applied to probe membrane integrit y, by using an electrolyte interacting with the silver electrode. Oxidation and reduction peaks were observed for non defect-free membranes. These pea ks were caused by oxidation of the silver electrode tip and their occurrenc e was a very sensitive means of measuring membrane integrity. The membrane was a barrier for the ion transport from the electrolyte solution to the el ectrode 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 prote ins 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 c apacitance of membranes from charged lipids. Protein binding was measured a s 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 substa nces could make the s-BLMs, produced by the described method, a valuable sy stem to be developed in the field of biosensing. (C) 2001 Elsevier Science B.V. All rights reserved.