Biomembrane structures, electrochemical

Membrane structures that contain the visual receptor protein rhodopsin were formed by detergent dialysis on platinum, silicon oxide, titanium oxide, and indium—tin oxide electrodes. Electrochemical impedance spectroscopy was used to evaluate the biomembrane structures and their electrical properties. A model equivalent circuit is proposed to describe the membrane-electrode interface. The data suggest that the surface structure is a relatively complete single-membrane bilayer with a coverage of 0.97 and with long-term stability/... 

BLM systems have been accepted as models of natural biomembranes for applications in medicine, industry, and clinical laboratories. BLMs have therefore been studied extensively in combination with various proteins, and are an excellent choice for the basis for development of electrochemical biosensors. The principles behind the development of BLM-based biosensors are quite simple. The sensing element should be biocompatible and should have a structure similar to a biomembrane. Chemically selective proteins may then be embedded into the membranes with substantial retention of binding activity. The simplest way to test transducer function is by using ligand-receptor binding interactions... 

Electrochemical impedance spectroscopy provides a sensitive means for characterizing the structure and electrical properties of the surface-bound membranes. The results from impedance analysis are consistent with a single biomembrane-mimetic structure being assembled on metal and semiconductor electrode surfaces. The structures formed by detergent dialysis may consist of a hydrophobic alkyl layer as one leaflet of a bilayer and the lipid deposited by dialysis as the other. Proteins surrounded by a bound lipid layer may simultaneously incorporate into pores in the alkylsilane layer by hydrophobic interactions during deposition of the lipid layer. This model is further supported by the composition of the surface-bound membranes and by Fourier transform infrared analyses (9). 

A good experimental model for biomembranes should possess a lipid bilayer structure, onto as well as into which functional entities can be embedded. Thus, since the 1960s, the two most widely used model membranes have been BLMs, also referred to as planar lipid bilayers and spherical liposomes. Planar BLMs and spherical liposomes are complementary to each other, since both types are derived from common amphipathic lipids and related compounds. Both are excellent model membrane systems, and have been extensively employed for investigations into a variety of physical, chemical, and biological functions. In the remainder of this chapter on membrane electrochemistry, the focus will be mainly on planar BLMs, because they are easily and have been investigated electrochemically (for K-posomes, see Refs. [3, 12, 34]). As a result... 

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