Building biomimetic membrane at a goldelectrode surface

Abstract

This article describes efforts to build a model biological membrane at a surface of a gold electrode. In this architecture, the membrane may be exposed to static electric fields on the order of 10⁷ to 10⁸ V m⁻¹. These fields are comparable in magnitude to the static electric field acting on a natural biological membrane. The field may be conveniently used to manipulate organic molecules within the membrane. By turning a knob on the control instrument one can deposit or lift the membrane from the gold surface. Electrochemical techniques can be used to control the physical state of the film while the infrared reflection absorption spectroscopy (IRRAS), surface imaging by STM and AFM and neutron scattering techniques can be employed to study conformational changes of organic molecules and their ordering within the membrane. This is shown on examples of membranes built of a simple zwitterionic phospholipid such as 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) and a mixed membrane composed of DMPC and cholesterol. The results illustrate the tremendous effect of cholesterol on the membrane structure. Two methods of membrane deposition at the electrode surface, namely by unilamellar vesicles fusion and using the Langmuir–Blodgett technique, are compared. Applications of these model systems to study interactions of small antibiotic peptides with lipids are discussed.