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Special Issue "Supported Lipid Membranes"

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Biomaterials".

Deadline for manuscript submissions: closed (30 September 2012)

Special Issue Editor

Guest Editor
Prof. Dr. Motomu Tanaka (Website)

Physical Chemistry of Biosystems, Institute for Physical Chemistry, Im Neuenheimer Feld 253, University of Heidelberg, D-69120 Heidelberg, Germany
Fax: +49 6221 54 4918
Interests: physics of biological membranes and carbohydrates; quantitative regulation of cell and tissue fate with soft interfaces; interfacing biomaterials and solid-based devices

Special Issue Information

Dear Colleagues,

Supported lipid membranes have been drawing attentions as a useful tool to connect soft, biological matter and hard solids. During the past several decays, an increasing number of publications evidenced that supported lipid membranes can be utilized not only to quantitatively understand structures and functions of cell membranes but also to create biocompatible/biomimetic interfaces. The main focus of the forthcoming special issue is to present a comprehensive overview to our readers by assembling state-of-the-art research articles and reviews on supported lipid membranes in material science in a broader sense. The topics covered by this special issue include basic researches from soft matter physics and surface/interface sciences as well as new classes of applications of supported membranes in biomedical sciences.

Prof. Dr. Motomu Tanaka
Guest Editor

Keywords

  • supported lipid membranes
  • physical characterization
  • theoretical modeling
  • biocompatible interface
  • biomimetic material

Published Papers (11 papers)

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Research

Jump to: Review

Open AccessArticle Dynamic Morphological Changes Induced By GM1 and Protein Interactions on the Surface of Cell-Sized Liposomes
Materials 2013, 6(6), 2522-2533; doi:10.3390/ma6062522
Received: 25 April 2013 / Revised: 25 May 2013 / Accepted: 29 May 2013 / Published: 19 June 2013
Cited by 3 | PDF Full-text (848 KB) | HTML Full-text | XML Full-text
Abstract
It is important to understand the physicochemical mechanisms that are responsible for the morphological changes in the cell membrane in the presence of various stimuli such as osmotic pressure. Lipid rafts are believed to play a crucial role in various cellular processes. [...] Read more.
It is important to understand the physicochemical mechanisms that are responsible for the morphological changes in the cell membrane in the presence of various stimuli such as osmotic pressure. Lipid rafts are believed to play a crucial role in various cellular processes. It is well established that Ctb (Cholera toxin B subunit) recognizes and binds to GM1 (monosialotetrahexosylganglioside) on the cell surface with high specificity and affinity. Taking advantage of Ctb-GM1 interaction, we examined how Ctb and GM1 molecules affect the dynamic movement of liposomes. GM1 a natural ligand for cholera toxin, was incorporated into liposome and the interaction between fluorescent Ctb and the liposome was analyzed. The interaction plays an important role in determining the various surface interaction phenomena. Incorporation of GM1 into membrane leads to an increase of the line tension leading to either rupture of liposome membrane or change in the morphology of the membrane. This change in morphology was found to be GM1 concentration specific. The interaction between Ctb-GM1 leads to fast and easy rupture or to morphological changes of the liposome. The interactions of Ctb and the glycosyl chain are believed to affect the surface and the curvature of the membrane. Thus, the results are highly beneficial in the study of signal transduction processes. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)
Open AccessArticle Supported Membranes Meet Flat Fluidics: Monitoring Dynamic Cell Adhesion on Pump-Free Microfluidics Chips Functionalized with Supported Membranes Displaying Mannose Domains
Materials 2013, 6(2), 669-681; doi:10.3390/ma6020669
Received: 18 October 2012 / Revised: 7 January 2013 / Accepted: 5 February 2013 / Published: 22 February 2013
Cited by 1 | PDF Full-text (1528 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we demonstrate the combination of supported membranes and so-called flat microfluidics, which enables one to manipulate liquids on flat chip surfaces via “inverse piezoelectric effect”. Here, an alternating external electric field applied to the inter-digital transducers excites a surface [...] Read more.
In this paper we demonstrate the combination of supported membranes and so-called flat microfluidics, which enables one to manipulate liquids on flat chip surfaces via “inverse piezoelectric effect”. Here, an alternating external electric field applied to the inter-digital transducers excites a surface acoustic wave on a piezoelectric substrate. Employing lithographic patterning of self-assembled monolayers of alkoxysilanes, we successfully confine a free-standing, hemi-cylindrical channel with the volume of merely 7 µL . The experimentally determined maximum flow velocity scales linearly with the acoustic power, suggesting that our current setup can drive liquids at the speed of up to 7 cm/s (corresponding to a shear rate of 280 s−1) without applying high pressures using a fluidic pump. After the establishment of the functionalization of fluidic chip surfaces with supported membranes, we deposited asymmetric supported membranes displaying well-defined mannose domains and monitored the dynamic adhesion of E. Coli HB101 expressing mannose-binding receptors. Despite of the further technical optimization required for the quantitative analysis, the obtained results demonstrate that the combination of supported membranes and flat fluidics opens a large potential to investigate dynamic adhesion of cells on biofunctional membrane surfaces with the minimum amount of samples, without any fluidic pump. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)
Open AccessArticle Horizontal Bilayer for Electrical and Optical Recordings
Materials 2012, 5(12), 2705-2730; doi:10.3390/ma5122705
Received: 15 October 2012 / Revised: 19 November 2012 / Accepted: 4 December 2012 / Published: 10 December 2012
Cited by 4 | PDF Full-text (2709 KB) | HTML Full-text | XML Full-text
Abstract
Artificial bilayer containing reconstituted ion channels, transporters and pumps serve as a well-defined model system for electrophysiological investigations of membrane protein structure–function relationship. Appropriately constructed microchips containing horizontally oriented bilayers with easy solution access to both sides provide, in addition, the possibility [...] Read more.
Artificial bilayer containing reconstituted ion channels, transporters and pumps serve as a well-defined model system for electrophysiological investigations of membrane protein structure–function relationship. Appropriately constructed microchips containing horizontally oriented bilayers with easy solution access to both sides provide, in addition, the possibility to investigate these model bilayer membranes and the membrane proteins therein with high resolution fluorescence techniques up to the single-molecule level. Here, we describe a bilayer microchip system in which long-term stable horizontal free-standing and hydrogel-supported bilayers can be formed and demonstrate its prospects particularly for single-molecule fluorescence spectroscopy and high resolution fluorescence microscopy in probing the physicochemical properties like phase behavior of the bilayer-forming lipids, as well as in functional studies of membrane proteins. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)
Open AccessArticle Polydopamine-Supported Lipid Bilayers
Materials 2012, 5(12), 2621-2636; doi:10.3390/ma5122621
Received: 8 October 2012 / Revised: 27 November 2012 / Accepted: 29 November 2012 / Published: 4 December 2012
Cited by 8 | PDF Full-text (1402 KB) | HTML Full-text | XML Full-text
Abstract
We report the formation of lipid membranes supported by a soft polymeric cushion of polydopamine. First, 20 nm thick polydopamine films were formed on mica substrates. Atomic force microscopy imaging indicated that these films were also soft with a surface roughness of [...] Read more.
We report the formation of lipid membranes supported by a soft polymeric cushion of polydopamine. First, 20 nm thick polydopamine films were formed on mica substrates. Atomic force microscopy imaging indicated that these films were also soft with a surface roughness of 2 nm under hydrated conditions. A zwitterionic phospholipid bilayer was then deposited on the polydopamine cushion by fusion of dimyristoylphosphatidylcholine (DMPC) and dioleoylphosphatidylcholine (DOPC) vesicles. Polydopamine films preserved the lateral mobility of the phospholipids as shown by fluorescence microscopy recovery after photobleaching (FRAP) experiments. Diffusion coefficients of ~5.9 and 7.2 µm2 s−1 were respectively determined for DMPC and DOPC at room temperature, values which are characteristic of lipids in a free standing bilayer system. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)
Open AccessArticle Cholesterol Organization in Phosphatidylcholine Liposomes: A Surface Plasmon Resonance Study
Materials 2012, 5(11), 2306-2325; doi:10.3390/ma5112306
Received: 29 August 2012 / Revised: 31 October 2012 / Accepted: 2 November 2012 / Published: 13 November 2012
Cited by 5 | PDF Full-text (744 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Models for the organization of sterols into regular arrays within phospholipid bilayers have been proposed previously. The existence of such arrays in real systems has been supported by the fact that concentration-dependent sterol properties show discontinuities at the cholesterol mole fractions corresponding [...] Read more.
Models for the organization of sterols into regular arrays within phospholipid bilayers have been proposed previously. The existence of such arrays in real systems has been supported by the fact that concentration-dependent sterol properties show discontinuities at the cholesterol mole fractions corresponding to regular lattice arrangements. Experimental results presented here are based on a surface plasmon resonance assay that was used to analyze rates of cyclodextrin-mediated removal of cholesterol from adsorbed liposomes at cholesterol mole fractions up to χC = 0.55. Two kinetic pools of cholesterol were detected; there was a fast pool present at χC > 0.25, and a slow pool, with a removal rate that was dependent on the initial χC but that did not vary as χC decreased during the course of one experiment. The cholesterol activity therefore seems to be affected by sample history as well as local concentration, which could be explained in terms of the formation of superlattices that are stable for relatively long times. We also describe a variation on the traditional lattice models, with phosphatidylcholine (PC) being treated as an arrangement of hexagonal tiles; the cholesterol is then introduced at any vertex point, without increasing the total area occupied by all the lipid molecules. This model is consistent with Langmuir trough measurements of total lipid area and provides a simple explanation for the maximum solubility of cholesterol in the PC bilayer. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)
Figures

Open AccessArticle Physisorbed Polymer-Tethered Lipid Bilayer with Lipopolymer Gradient
Materials 2012, 5(11), 2243-2257; doi:10.3390/ma5112243
Received: 15 October 2012 / Revised: 6 November 2012 / Accepted: 6 November 2012 / Published: 8 November 2012
Cited by 7 | PDF Full-text (5963 KB) | HTML Full-text | XML Full-text
Abstract
Physisorbed polymer-tethered lipid bilayers consisting of phospholipids and lipopolymers represent an attractive planar model membrane platform, in which bilayer fluidity and membrane elastic properties can be regulated through lipopolymer molar concentration. Herein we report a method for the fabrication of such a [...] Read more.
Physisorbed polymer-tethered lipid bilayers consisting of phospholipids and lipopolymers represent an attractive planar model membrane platform, in which bilayer fluidity and membrane elastic properties can be regulated through lipopolymer molar concentration. Herein we report a method for the fabrication of such a planar model membrane system with a lateral gradient of lipopolymer density. In addition, a procedure is described, which leads to a sharp boundary between regions of low and high lipopolymer molar concentrations. Resulting gradients and sharp boundaries are visualized on the basis of membrane buckling structures at elevated lipopolymer concentrations using epifluorescence microscopy and atomic force microscopy. Furthermore, results from spot photobleaching experiments are presented, which provide insight into the lipid lateral fluidity in these model membrane architectures. The presented experimental data highlight a planar, solid-supported membrane characterized by fascinating length scale-dependent dynamics and elastic properties with remarkable parallels to those observed in cellular membranes. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)
Figures

Open AccessArticle Lateral Dynamics in Polymer-Supported Membranes
Materials 2012, 5(10), 1923-1932; doi:10.3390/ma5101923
Received: 11 September 2012 / Revised: 30 September 2012 / Accepted: 12 October 2012 / Published: 19 October 2012
Cited by 4 | PDF Full-text (139 KB) | HTML Full-text | XML Full-text
Abstract
We investigate the lateral dynamics in a purely viscous lipid membrane which is supported by a thin polymer sheet (polymer-supported membrane). The generalized frequency-dependent mobility tensor of the polymer-supported membrane is obtained by taking into account the viscoelasticity of the polymer sheet. [...] Read more.
We investigate the lateral dynamics in a purely viscous lipid membrane which is supported by a thin polymer sheet (polymer-supported membrane). The generalized frequency-dependent mobility tensor of the polymer-supported membrane is obtained by taking into account the viscoelasticity of the polymer sheet. Due to its viscoelasticity, the cross-correlation functions of two particles embedded in the membrane exhibit an anomalous diffusion. A useful relation for two-point microrheology connecting the cross-correlation function and the modulus of the polymer sheet is provided. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)

Review

Jump to: Research

Open AccessReview Biotechnology Applications of Tethered Lipid Bilayer Membranes
Materials 2012, 5(12), 2637-2657; doi:10.3390/ma5122637
Received: 8 October 2012 / Revised: 23 November 2012 / Accepted: 26 November 2012 / Published: 7 December 2012
Cited by 26 | PDF Full-text (1413 KB) | HTML Full-text | XML Full-text
Abstract
The importance of cell membranes in biological systems has prompted the development of model membrane platforms that recapitulate fundamental aspects of membrane biology, especially the lipid bilayer environment. Tethered lipid bilayers represent one of the most promising classes of model membranes and [...] Read more.
The importance of cell membranes in biological systems has prompted the development of model membrane platforms that recapitulate fundamental aspects of membrane biology, especially the lipid bilayer environment. Tethered lipid bilayers represent one of the most promising classes of model membranes and are based on the immobilization of a planar lipid bilayer on a solid support that enables characterization by a wide range of surface-sensitive analytical techniques. Moreover, as the result of molecular engineering inspired by biology, tethered bilayers are increasingly able to mimic fundamental properties of natural cell membranes, including fluidity, electrical sealing and hosting transmembrane proteins. At the same time, new methods have been employed to improve the durability of tethered bilayers, with shelf-lives now reaching the order of weeks and months. Taken together, the capabilities of tethered lipid bilayers have opened the door to biotechnology applications in healthcare, environmental monitoring and energy storage. In this review, several examples of such applications are presented. Beyond the particulars of each example, the focus of this review is on the emerging design and characterization strategies that made these applications possible. By drawing connections between these strategies and promising research results, future opportunities for tethered lipid bilayers within the biotechnology field are discussed. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)
Figures

Open AccessReview Substrate Effects on the Formation Process, Structure and Physicochemical Properties of Supported Lipid Bilayers
Materials 2012, 5(12), 2658-2680; doi:10.3390/ma5122658
Received: 29 September 2012 / Revised: 29 November 2012 / Accepted: 29 November 2012 / Published: 7 December 2012
Cited by 25 | PDF Full-text (1376 KB) | HTML Full-text | XML Full-text
Abstract
Supported lipid bilayers are artificial lipid bilayer membranes existing at the interface between solid substrates and aqueous solution. Surface structures and properties of the solid substrates affect the formation process, fluidity, two-dimensional structure and chemical activity of supported lipid bilayers, through the [...] Read more.
Supported lipid bilayers are artificial lipid bilayer membranes existing at the interface between solid substrates and aqueous solution. Surface structures and properties of the solid substrates affect the formation process, fluidity, two-dimensional structure and chemical activity of supported lipid bilayers, through the 1–2 nm thick water layer between the substrate and bilayer membrane. Even on SiO2/Si and mica surfaces, which are flat and biologically inert, and most widely used as the substrates for the supported lipid bilayers, cause differences in the structure and properties of the supported membranes. In this review, I summarize several examples of the effects of substrate structures and properties on an atomic and nanometer scales on the solid-supported lipid bilayers, including our recent reports. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)
Open AccessReview Cell-Sized Liposomes and Droplets: Real-World Modeling of Living Cells
Materials 2012, 5(11), 2292-2305; doi:10.3390/ma5112292
Received: 18 October 2012 / Revised: 8 November 2012 / Accepted: 8 November 2012 / Published: 13 November 2012
Cited by 15 | PDF Full-text (878 KB) | HTML Full-text | XML Full-text
Abstract
Recent developments in studies concerning cell-sized vesicles, such as liposomes with a lipid bilayer and water-in-oil droplets covered by a lipid monolayer, aim to realize the real-world modeling of living cells. Compartmentalization with a membrane boundary is essential for the organization of [...] Read more.
Recent developments in studies concerning cell-sized vesicles, such as liposomes with a lipid bilayer and water-in-oil droplets covered by a lipid monolayer, aim to realize the real-world modeling of living cells. Compartmentalization with a membrane boundary is essential for the organization of living systems. Due to the relatively large surface/volume ratio in microconfinement, the membrane interface influences phenomena related to biological functions. In this article, we mainly focus on the following subjects: (i) conformational transition of biopolymers in a confined space; (ii) molecular association on the membrane surface; and (iii) remote control of cell-sized membrane morphology. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)
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Open AccessReview Challenges in the Development of Functional Assays of Membrane Proteins
Materials 2012, 5(11), 2205-2242; doi:10.3390/ma5112205
Received: 29 September 2012 / Revised: 25 October 2012 / Accepted: 1 November 2012 / Published: 7 November 2012
Cited by 14 | PDF Full-text (1681 KB) | HTML Full-text | XML Full-text
Abstract
Lipid bilayers are natural barriers of biological cells and cellular compartments. Membrane proteins integrated in biological membranes enable vital cell functions such as signal transduction and the transport of ions or small molecules. In order to determine the activity of a protein [...] Read more.
Lipid bilayers are natural barriers of biological cells and cellular compartments. Membrane proteins integrated in biological membranes enable vital cell functions such as signal transduction and the transport of ions or small molecules. In order to determine the activity of a protein of interest at defined conditions, the membrane protein has to be integrated into artificial lipid bilayers immobilized on a surface. For the fabrication of such biosensors expertise is required in material science, surface and analytical chemistry, molecular biology and biotechnology. Specifically, techniques are needed for structuring surfaces in the micro- and nanometer scale, chemical modification and analysis, lipid bilayer formation, protein expression, purification and solubilization, and most importantly, protein integration into engineered lipid bilayers. Electrochemical and optical methods are suitable to detect membrane activity-related signals. The importance of structural knowledge to understand membrane protein function is obvious. Presently only a few structures of membrane proteins are solved at atomic resolution. Functional assays together with known structures of individual membrane proteins will contribute to a better understanding of vital biological processes occurring at biological membranes. Such assays will be utilized in the discovery of drugs, since membrane proteins are major drug targets. Full article
(This article belongs to the Special Issue Supported Lipid Membranes)
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