Planar supported lipid bilayer

The basic procedure for creating addressed aqueous compartments above individual bilayers is outline in Figure 6.6. In the first step, a lithographically patterned PDMS mold is brought into direct contact with a planar supported lipid bilayer containing covalently attached ligands, to create hermetically sealed compartments by microcontact displacement... 

Conboy JC, McReynolds KD, Gervay-Hague J, Saavedra SS (2002) Quantitative measurements of recombinant HIV surface glycoprotein 120 binding to several glycosphin-golipids expressed in planar supported lipid bilayers. J Am Chem Soc 124 968-977... 

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. 

Supported Planar BLMs (Lipid Bilayers) Formation, Methods of Study, and Applications... 

First efforts were done to prove the applicability of an aerogel matrix as a membrane support. Planar phospholipid bilayers were deposited on silica aerogel surfaces and their lateral mobility and homogeneity were studied [27]. It is expected that the permeable nature of the porous materials, such as aerogels, provide new advantages for supported lipid bilayer systems, such as for example, better accommodation of proteins. 

Because of their advanced level of development, high sensitivity, and broad applicability, fluorescence spectroscopy with labeled LUVs and planar bilayer conductance experiments are the two techniques of choice to study synthetic transport systems. The broad applicability of the former also includes ion carriers, but it is extremely difficult to differentiate a carrier from a channel or pore mechanism by LUV experiments. However, the breadth and depth accessible with fluorogenic vesicles in a reliable user-friendly manner are unmatched by any other technique. Planar bilayer conductance experiments are restricted to ion channels and pores and are commonly accepted as substantial evidence for their existence. Exflemely informative, these fragile single-molecule experiments can be very difficult to execute and interpret. Another example for alternative techniques to analyze synthetic transport systems in LUVs is ion-selective electrodes. Conductance experiments in supported lipid bilayer membranes may be mentioned as well. Although these methods are less frequently used, they may be added to the repertoire of the supramolecular chemist. 

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. 

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. 

The artificial lipid bilayer is often prepared via the vesicle-fusion method [8]. In the vesicle fusion process, immersing a solid substrate in a vesicle dispersion solution induces adsorption and rupture of the vesicles on the substrate, which yields a planar and continuous lipid bilayer structure (Figure 13.1) [9]. The Langmuir-Blodgett transfer process is also a useful method [10]. These artificial lipid bilayers can support various biomolecules [11-16]. However, we have to take care because some transmembrane proteins incorporated in these artificial lipid bilayers interact directly with the substrate surface due to a lack of sufficient space between the bilayer and the substrate. This alters the native properties of the proteins and prohibits free diffusion in the lipid bilayer [17[. To avoid this undesirable situation, polymer-supported bilayers [7, 18, 19] or tethered bilayers [20, 21] are used. 

Fig. 6.9. A Spontaneous Raman spectrum of d62-DPPC lipids and its decomposition into Lorentzian line profiles. B Normalized multiplex CARS spectra (dots) of a planar-supported bilayer and monolayer formed by d62-DPPC on a glass-water interface for parallel-polarized input beams, together with the fit using the center frequency and line width parameters extracted from the decomposition analysis in (A) (solid line). The spectrum exposure time was 0.64 s. Error bars indicate the shot-noise standard deviation (Copyright American Chemical Society [70])...

Rytomaa, M., and Kinnunen, P.KJ., 1995, Reversibility of the binding of cytochrome c to liposomes. Implications for lipid-protein interactions. /. Biol. Chem., 270 3197-3202 Salamon, Z., and Tollin, G., 1996, Surface plasmon resonance studies of complex formation between cytochrome c and bovine cytochrome c oxidase incorporated into a supported planar lipid bilayer. II. Binding of cytochrome c to oxidase-containing cardiolipin /phosphatidylcholine membranes. Biophys. J., 71 858-867 Salamon, Z., and Tollin, G., 1997, Interaction ofhorse heart cytochrome c with lipid bilayer membranes effects on redox potentials. J. Bioenerg. Biomembr. 29 211-221 Scarlett, J.L., and Murphy, M.P., 1997, Release of apoptogenic proteins from the... 

Ye Q, Konradi R, Textor M, Reimhult E (2009) Liposomes tethered to omega-functional PEG brushes and induced formation of PEG brush supported planar lipid bilayers. Langmuir 25 13534-13539... 

Wagner ML, Tamm LK (2000) Tethered polymer-supported planar lipid bilayers for reconstitution of integral membrane proteins Silane-polyethyleneglycol-lipid as a cushion and covalent linker. Biophys J 79 1400-1414... 

Crane JM, Kiessling V, Tamm LK. Measuring lipid asymmetry in planar supported bilayers by fluorescence interference contrast microscopy. Langmuir 2005 21 1377-1388. 

Shaw JE, Slade A, Yip CM. Simultaneous in situ total inter- 65. nal reflectance fluorescence/atomic force microscopy studies of DPPC/dPOPC microdomains in supported planar lipid bilayers. J. 

Biosensors based on metal-supported bilayer lipid membranes. BLMs, especially s-BLMs, have been used in the last three years as lipid bilayer-based biosensors [10,11,74-76,82], Hianik etal [75] have carried out a detailed physical study on the elasticity modulus of s-BLMs. They found that the dynamic viscosity of s-BLMs is one order of magnitude less than that of conventional BLMs [75]. It should be mentioned that in the s-BLM system, albeit attractive for certain purposes such as biosensors and molecular devices, the metallic substrate precludes ion translocation across the lipid bilayer. Therefore, the pursuit of a simple method for obtaining long-lived, planar BLMs separating two aqueous media has been an elusive one until now [81]. As reported, this much improved... 

A home-built solid state NMR probe for membrane protein studies has been described by Kim et al. Proteins in highly oriented lipid bilayer samples are useful to study membrane protein structure determination. Planar lipid bilayers aligned and supported on glass slide were prepared. The stack of glass slide with planar lipid bilayers is not well fit for commercial solid state NMR probe with round coil. Therefore, homebuilt solid state NMR probe was built by Kim et al. The overall filling factor of the coil was much better and the large surface area increased the extent to orientation by providing uniform environments for the... 

FIGURE 24.3 Schematic representation of a combinatorial AFM-fluorescence microscopy experiment, depicting AFM imaging of a supported planar lipid bilayer (SPB) containing membrane domains and/or proteins. 

Slade, A., Luh, J., Ho, S., and Yip, C. M. 2002. Single molecule imaging of supported planar lipid bilayer—Reconstituted human insulin receptors by in situ scanning probe microscopy, / Struct Biol 137, 283-291. 

Puu, G. and Gustafson, I. 1997. Planar lipid bilayers on solid supports from liposomes—Factors of importance for kinetics and stability, Biochim Biophys Acta 1327,149-161. 

Fig. 1 Two basic types of BLMs (planar lipid bilayers), (a) A conventional BLM separating two aqueous solutions in formation [1] (a short movie illustrating the BLM-forming process) may be seen by visiting the URL http //ivwiv.msu.edu/user/ottoval soapJtubble.html] (b) supported BLMs (c) a BLM on metal substrate (s-BLM) (d) a salt-bridge supported BLM (sb-BLM). P-G stands for Plateau-Gibbs border that supports the BLM [2, 3].

Generally, either AC (e.g. EIS) or DC is used for investigating BLMs. Recently, a simple setup for measurements of electrical properties of supported planar lipid bilayers (s-BLMs), using a complementary AC/DC method has been reported [3,13]. The results obtained demonstrated the usefulness of such an approach for studying BLMs. The frequency dependence of resistance and capacitance makes it possible to compare different pubKshed data obtained by AC at different frequencies or DC. In some experiments, capacitance... 

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