Planar bilayer

A comparison of the PV performance of this mixed HJ device (Uchida et al., 2004) and that of a bilayer, planar HJ CuPc-Qo cell (Xue et al., 2004a) at various illumination intensities is shown in Figure 12.8. The mixed HJ... 

In addition, the possibility of demixing favors phase separation. The coexistence of micelles and bilayers in two separate phases has recently been explained in terms of the demixing associated with differences in mono-layers curvature [38]. A significant demixing in the same phase between small vesicles and extended bilayer, planar or sponge, could upon up new ways of controlling spontaneous vesiculation. 

Protems can be physisorbed or covalently attached to mica. Another method is to innnobilise and orient them by specific binding to receptor-fiinctionalized planar lipid bilayers supported on the mica sheets [15]. These surfaces are then brought into contact in an aqueous electrolyte solution, while the pH and the ionic strength are varied. Corresponding variations in the force-versus-distance curve allow conclusions about protein confomiation and interaction to be drawn [99]. The local electrostatic potential of protein-covered surfaces can hence be detemiined with an accuracy of 5 mV. 

This parameter corresponds to cylindrical packing shapes. Surfactants and amphiphiles falling in this range often produce planar bilayers and lamellar mesophases. Such cylindrical building blocks also contribute to many... 

Knowles, B. H., Blatt, M. R., Tester, M., et al., 1989. A cytosolic 5-endo-toxin from Bacillus thurigiensis var. israelensis forms cation-selective channels in planar lipid bilayers. FEES Letters 244 259-262. 

This review addresses the issues of the chemical and physical processes whereby inorganic anions and cations are selectively retained by or passed through cell membranes. The channel and carrier mechanisms of membranes permeation are treated by means of model systems. The models are the planar lipid bilayer for the cell membrane, Gramicidin for the channel mechanism, and Valinomycin for the carrier mechanism. 

As first shown by Hladky and Haydon 7,8), it is possible to observe the current due to a single transmembrane channel by using extensions of the planar lipid hilaver approach of Mueller and Rudin 9). The basic system is shown in Fig. 2 and is commonly referred to as the black lipid membrane (BLM) method. This is because, as the lipid in the hole between the two chambers thins, the areas that have become planar bilayers are seen as black. Additional terms are bilayer lipid membranes or planar lipid bilayer membranes. These lipid bilayer membranes, particularly those which are solvent free, have capacitances which are very close to those of biological membranes. 

Fig. 2. Experimental set up for characterizing channel or carrier induced currents crossing the small area of a planar lipid bilayer which is schematically shown in enlarged view. Net current derives from either an applied potential or a concentration gradient...

Fig. 3. Step conductance changes across planar bilayer due to Gramicidin A (traces A and C), D Leu2 Gramicidin A (trace B) and N-acetyl desformyl Gramicidin A (trace D).

A. Side view of channel spanning the lipid layer of a planar lipid bilayer, The structure is comprised of two monomers, each in a left-handed, single stranded p -helical conformation, and joined together at the head or formyl end by means of six, intermolecular hydrogen bonds. The two formyl protons are seen at the center of the structure in this view. Replacement of these protons by methyls destabilizes the conducting dimer as shown with N-acetyl desformyl Gramicidin A (Fig. 3D). 

The use of Upid bilayers as a relevant model of biological membranes has provided important information on the structure and function of cell membranes. To utilize the function of cell membrane components for practical applications, a stabilization of Upid bilayers is imperative, because free-standing bilayer lipid membranes (BLMs) typically survive for minutes to hours and are very sensitive to vibration and mechanical shocks [156,157]. The following concept introduces S-layer proteins as supporting structures for BLMs (Fig. 15c) with largely retained physical features (e.g., thickness of the bilayer, fluidity). Electrophysical and spectroscopical studies have been performed to assess the appUcation potential of S-layer-supported lipid membranes. The S-layer protein used in aU studies on planar BLMs was isolated fromB. coagulans E38/vl. 

Supported lipid bilayers on planar silicon substrates have been formed using S-layer protein from B. coagulans E38/vl and from B. sphaericus CCM 2177 as support onto which l,2-dimyristoyl-OT-glycero-3-phosphocholine (DMPC) (pure or mixtures with 30% cholesterol) or DPPC bilayers were deposited by the Langmuir-Blodgett-technique (Pig. 

Planar phospholipid bilayer [137], tetraether lipid monolayer [21]... 

Spherical unilamellar liposomes [119] Planar phospholipid bilayer [141,142]... 

TH Tien, A Ottova-Leitmannova. Membrane Biophysics as Viewed from Experimental Bilayer Lipid Membranes Planar Lipid Bilayers and Spherical Liposomes. New York Elsevier Science, 2000. 

Pharmacological Methods and Results. The data upon which the following discussion is based were accumulated using three techniques mouse bioassay, displacement of radiolabelled saxitoxin from rabbit brain membranes, and blockage of sodium conductance through rat sarcolemmal sodium channels incorporated into planar lipid bilayers. The results are summarized in Figures 11 and 12. 

Tamplin et. al. (54) observed that V. cholerae and A. hydrophila cell extracts contained substances with TTX-like biological activity in tissue culture assay, counteracting the lethal effect of veratridine on ouabain-treated mouse neuroblastoma cells. Concentrations of TTX-like activity ranged from 5 to 100 ng/L of culture when compared to standard TTX. The same bacterial extracts also displaced radiolabelled STX from rat brain membrane sodium channel receptors and inhibited the compound action potential of frog sciatic nerve. However, the same extracts did not show TTX-like blocking events of sodium current when applied to rat sarcolemmal sodium channels in planar lipid bilayers. 

We have developed a series of models in which 8-12 monomers were packed in an antiparallel manner to form the channel. The kinetics of pore formation in liposomes (9) and the dependence of planar bilayer conductance on toxin... 

The purified membrane bound Na,K-ATPase from kidney adsorbs to planar lipid bilayers and transient currents can be elicited upon release of caged ATP [99,100], The... 

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