1
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Grusky DS, Bhattacharya A, Boxer SG. Secondary Ion Mass Spectrometry of Single Giant Unilamellar Vesicles Reveals Compositional Variability. J Am Chem Soc 2023; 145:27521-27530. [PMID: 38056605 PMCID: PMC10904076 DOI: 10.1021/jacs.3c09039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
Giant unilamellar vesicles (GUVs) are a widely used model system to interrogate lipid phase behavior, study biomembrane mechanics, reconstitute membrane proteins, and provide a chassis for synthetic cells. It is generally assumed that the composition of individual GUVs is the same as the nominal stock composition; however, there may be significant compositional variability between individual GUVs. Although this compositional heterogeneity likely impacts phase behavior, the function and incorporation of membrane proteins, and the encapsulation of biochemical reactions, it has yet to be directly quantified. To assess heterogeneity, we use secondary ion mass spectrometry (SIMS) to probe the composition of individual GUVs using non-perturbing isotopic labels. Both 13C- and 2H-labeled lipids are incorporated into a ternary mixture, which is then used to produce GUVs via gentle hydration or electroformation. Simultaneous detection of seven different ion species via SIMS allows for the concentration of 13C- and 2H-labeled lipids in single GUVs to be quantified using calibration curves, which correlate ion intensity to composition. Additionally, the relative concentration of 13C- and 2H-labeled lipids is assessed for each GUV via the ion ratio 2H-/13C-, which is highly sensitive to compositional differences between individual GUVs and circumvents the need for calibration by using standards. Both quantification methods suggest that gentle hydration produces GUVs with greater compositional variability than those formed by electroformation. However, both gentle hydration and electroformation display standard deviations in composition (n = 30 GUVs) on the order of 1-4 mol %, consistent with variability seen in previous indirect measurements.
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Affiliation(s)
- Dashiel S Grusky
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Ahanjit Bhattacharya
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
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2
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Miller EJ, Phan MD, Shah J, Honerkamp-Smith AR. Passive and reversible area regulation of supported lipid bilayers in response to fluid flow. Biophys J 2023; 122:2242-2255. [PMID: 36639867 PMCID: PMC10257118 DOI: 10.1016/j.bpj.2023.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/21/2022] [Accepted: 01/09/2023] [Indexed: 01/14/2023] Open
Abstract
Biological and model membranes are frequently subjected to fluid shear stress. However, membrane mechanical responses to flow remain incompletely described. This is particularly true of membranes supported on a solid substrate, and the influences of membrane composition and substrate roughness on membrane flow responses remain poorly understood. Here, we combine microfluidics, fluorescence microscopy, and neutron reflectivity to explore how supported lipid bilayer patches respond to controlled shear stress. We demonstrate that lipid membranes undergo a significant, passive, and partially reversible increase in membrane area due to flow. We show that these fluctuations in membrane area can be constrained, but not prevented, by increasing substrate roughness. Similar flow-induced changes to membrane structure may contribute to the ability of living cells to sense and respond to flow.
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Affiliation(s)
| | - Minh D Phan
- Large-Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Center for Neutron Science, Department of Chemical & Biomolecular Engineering, University of Delaware, Newark, Delaware
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3
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Kusumi A, Tsunoyama TA, Tang B, Hirosawa KM, Morone N, Fujiwara TK, Suzuki KGN. Cholesterol- and actin-centered view of the plasma membrane: updating the Singer-Nicolson fluid mosaic model to commemorate its 50th anniversary †. Mol Biol Cell 2023; 34:pl1. [PMID: 37039596 PMCID: PMC10162409 DOI: 10.1091/mbc.e20-12-0809] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 12/07/2022] [Accepted: 02/07/2023] [Indexed: 04/12/2023] Open
Abstract
Two very polarized views exist for understanding the cellular plasma membrane (PM). For some, it is the simple fluid described by the original Singer-Nicolson fluid mosaic model. For others, due to the presence of thousands of molecular species that extensively interact with each other, the PM forms various clusters and domains that are constantly changing and therefore, no simple rules exist that can explain the structure and molecular dynamics of the PM. In this article, we propose that viewing the PM from its two predominant components, cholesterol and actin filaments, provides an excellent and transparent perspective of PM organization, dynamics, and mechanisms for its functions. We focus on the actin-induced membrane compartmentalization and lipid raft domains coexisting in the PM and how they interact with each other to perform PM functions. This view provides an important update of the fluid mosaic model.
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Affiliation(s)
- Akihiro Kusumi
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa 904-0495, Japan
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
| | - Taka A. Tsunoyama
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa 904-0495, Japan
| | - Bo Tang
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa 904-0495, Japan
| | - Koichiro M. Hirosawa
- Institute for Glyco-Core Research (iGCORE), Gifu University, Gifu 501-1193, Japan
| | - Nobuhiro Morone
- MRC Toxicology Unit, University of Cambridge, Cambridge CB2 1QR, UK
| | - Takahiro K. Fujiwara
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
| | - Kenichi G. N. Suzuki
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
- Institute for Glyco-Core Research (iGCORE), Gifu University, Gifu 501-1193, Japan
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4
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Refinement of Singer-Nicolson fluid-mosaic model by microscopy imaging: Lipid rafts and actin-induced membrane compartmentalization. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184093. [PMID: 36423676 DOI: 10.1016/j.bbamem.2022.184093] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 11/22/2022]
Abstract
This year celebrates the 50th anniversary of the Singer-Nicolson fluid mosaic model for biological membranes. The next level of sophistication we have achieved for understanding plasma membrane (PM) structures, dynamics, and functions during these 50 years includes the PM interactions with cortical actin filaments and the partial demixing of membrane constituent molecules in the PM, particularly raft domains. Here, first, we summarize our current knowledge of these two structures and emphasize that they are interrelated. Second, we review the structure, molecular dynamics, and function of raft domains, with main focuses on raftophilic glycosylphosphatidylinositol-anchored proteins (GPI-APs) and their signal transduction mechanisms. We pay special attention to the results obtained by single-molecule imaging techniques and other advanced microscopy methods. We also clarify the limitations of present optical microscopy methods for visualizing raft domains, but emphasize that single-molecule imaging techniques can "detect" raft domains associated with molecules of interest in the PM.
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5
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Bagatolli LA, Stock RP. Lipids, membranes, colloids and cells: A long view. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183684. [PMID: 34166642 DOI: 10.1016/j.bbamem.2021.183684] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/01/2021] [Accepted: 06/16/2021] [Indexed: 12/13/2022]
Abstract
This paper revisits long-standing ideas about biological membranes in the context of an equally long-standing, but hitherto largely unappreciated, perspective of the cell based on concepts derived from the physics and chemistry of colloids. Specifically, we discuss important biophysical aspects of lipid supramolecular structure to understand how the intracellular milieu may constrain lipid self-assembly. To this end we will develop four lines of thought: first, we will look at the historical development of the current view of cellular structure and physiology, considering also the plurality of approaches that influenced its formative period. Second, we will review recent basic research on the structural and dynamical properties of lipid aggregates as well as the role of phase transitions in biophysical chemistry and cell biology. Third, we will present a general overview of contemporary studies into cellular compartmentalization in the context of a very rich and mostly forgotten general theory of cell physiology called the Association-Induction Hypothesis, which was developed around the time that the current view of cells congealed into its present form. Fourth, we will examine some recent developments in cellular studies, mostly from our laboratory, that raise interesting issues about the dynamical aspects of cell structure and compartmentalization. We will conclude by suggesting what we consider are relevant questions about the nature of cellular processes as emergent phenomena.
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Affiliation(s)
- Luis A Bagatolli
- Instituto de Investigación Médica Mercedes y Martín Ferreyra - INIMEC (CONICET)-Universidad Nacional de Córdoba, Friuli 2434, 5016 Córdoba, Argentina; Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; MEMPHYS - International and Interdisciplinary research network, Denmark.
| | - Roberto P Stock
- MEMPHYS - International and Interdisciplinary research network, Denmark
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6
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Kataoka-Hamai C, Kawakami K. Domain Sorting in Giant Unilamellar Vesicles Adsorbed on Glass. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:1082-1088. [PMID: 33440115 DOI: 10.1021/acs.langmuir.0c02843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Giant unilamellar vesicles (GUVs) adsorb to a solid surface and rupture to form a planar bilayer patch. These bilayer patches are used to investigate the properties and functions of biological membranes. Therefore, it is crucial to understand the mechanisms of GUV adsorption. In this study, we investigate the adsorption of phase-separated GUVs on glass using fluorescence microscopy. GUVs containing liquid-ordered (Lo) and liquid-disordered (Ld) phases underwent domain sorting after adsorption. The Ld domain in the unbound region migrated to the highly curved region near the edge of the adsorbed region. Additionally, the Lo phase grew linearly along the edge of the adsorbed region, creating a thin ring-like domain. After the domain sorting event, the GUV ruptured to form a planar bilayer patch with circular-patterned domains in the initially adsorbed area. We found that domain sorting was promoted by increasing the extent of GUV deformation. These results suggest that both the Ld and Lo domains are reorganized for stabilizing the curved bilayer region in adsorbed GUVs.
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Affiliation(s)
- Chiho Kataoka-Hamai
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Kohsaku Kawakami
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
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7
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Miller EJ, Ratajczak AM, Anthony AA, Mottau M, Rivera Gonzalez XI, Honerkamp-Smith AR. Divide and conquer: How phase separation contributes to lateral transport and organization of membrane proteins and lipids. Chem Phys Lipids 2020; 233:104985. [DOI: 10.1016/j.chemphyslip.2020.104985] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 09/18/2020] [Accepted: 09/28/2020] [Indexed: 01/06/2023]
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8
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Direct imaging of liquid domains in membranes by cryo-electron tomography. Proc Natl Acad Sci U S A 2020; 117:19713-19719. [PMID: 32759217 DOI: 10.1073/pnas.2002245117] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Images of micrometer-scale domains in lipid bilayers have provided the gold standard of model-free evidence to understand the domains' shapes, sizes, and distributions. Corresponding techniques to directly and quantitatively assess smaller (nanoscale and submicron) liquid domains have been limited. Researchers commonly seek to correlate activities of membrane proteins with attributes of the domains in which they reside; doing so hinges on identification and characterization of membrane domains. Although some features of membrane domains can be probed by indirect methods, these methods are often constrained by the limitation that data must be analyzed in the context of models that require multiple assumptions or parameters. Here, we address this challenge by developing and testing two methods of identifying submicron domains in biomimetic membranes. Both methods leverage cryo-electron tomograms of ternary membranes under vitrified, hydrated conditions. The first method is optimized for probe-free applications: Domains are directly distinguished from the surrounding membrane by their thickness. This technique quantitatively and accurately measures area fractions of domains, in excellent agreement with known phase diagrams. The second method is optimized for applications in which a single label is deployed for imaging membranes by both high-resolution cryo-electron tomography and diffraction-limited optical microscopy. For this method, we test a panel of probes, find that a trimeric mCherry label performs best, and specify criteria for developing future high-performance, dual-use probes. These developments have led to direct and quantitative imaging of submicron membrane domains in vitrified, hydrated vesicles.
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9
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Obeid S, Guyomarc'h F. Atomic force microscopy of food assembly: Structural and mechanical insights at the nanoscale and potential opportunities from other fields. FOOD BIOSCI 2020. [DOI: 10.1016/j.fbio.2020.100654] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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10
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Effects of the peptide Magainin H2 on Supported Lipid Bilayers studied by different biophysical techniques. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2635-2643. [DOI: 10.1016/j.bbamem.2018.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 10/02/2018] [Indexed: 11/24/2022]
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11
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Gunderson RS, Honerkamp-Smith AR. Liquid-liquid phase transition temperatures increase when lipid bilayers are supported on glass. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1965-1971. [DOI: 10.1016/j.bbamem.2018.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/30/2018] [Accepted: 05/03/2018] [Indexed: 02/02/2023]
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12
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Weiss M, Frohnmayer JP, Benk LT, Haller B, Janiesch JW, Heitkamp T, Börsch M, Lira RB, Dimova R, Lipowsky R, Bodenschatz E, Baret JC, Vidakovic-Koch T, Sundmacher K, Platzman I, Spatz JP. Sequential bottom-up assembly of mechanically stabilized synthetic cells by microfluidics. NATURE MATERIALS 2018; 17:89-96. [PMID: 29035355 DOI: 10.1038/nmat5005] [Citation(s) in RCA: 255] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/12/2017] [Indexed: 05/21/2023]
Abstract
Compartments for the spatially and temporally controlled assembly of biological processes are essential towards cellular life. Synthetic mimics of cellular compartments based on lipid-based protocells lack the mechanical and chemical stability to allow their manipulation into a complex and fully functional synthetic cell. Here, we present a high-throughput microfluidic method to generate stable, defined sized liposomes termed 'droplet-stabilized giant unilamellar vesicles (dsGUVs)'. The enhanced stability of dsGUVs enables the sequential loading of these compartments with biomolecules, namely purified transmembrane and cytoskeleton proteins by microfluidic pico-injection technology. This constitutes an experimental demonstration of a successful bottom-up assembly of a compartment with contents that would not self-assemble to full functionality when simply mixed together. Following assembly, the stabilizing oil phase and droplet shells are removed to release functional self-supporting protocells to an aqueous phase, enabling them to interact with physiologically relevant matrices.
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Affiliation(s)
- Marian Weiss
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
- Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Johannes Patrick Frohnmayer
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
- Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Lucia Theresa Benk
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
- Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Barbara Haller
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
- Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Jan-Willi Janiesch
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
- Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Thomas Heitkamp
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Michael Börsch
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Rafael B Lira
- Theory & Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Rumiana Dimova
- Theory & Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Reinhard Lipowsky
- Theory & Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Eberhard Bodenschatz
- Laboratory for Fluid Dynamics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - Jean-Christophe Baret
- Droplets, Membranes and Interfaces, Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
- Soft Micro Systems, CNRS, Univ. Bordeaux, CRPP, UPR 8641, 115 Avenue Schweitzer, 33600 Pessac, France
| | - Tanja Vidakovic-Koch
- Process System Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
| | - Kai Sundmacher
- Process System Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
- Otto-von-Guericke University Magdeburg, Process Systems Engineering, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - Ilia Platzman
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
- Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Joachim P Spatz
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
- Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
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13
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Teske N, Sibold J, Schumacher J, Teiwes NK, Gleisner M, Mey I, Steinem C. Continuous Pore-Spanning Lipid Bilayers on Silicon Oxide-Coated Porous Substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:14175-14183. [PMID: 29148811 DOI: 10.1021/acs.langmuir.7b02727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A number of techniques has been developed and analyzed in recent years to generate pore-spanning membranes (PSMs). While quite a number of methods rely on nanoporous substrates, only a few use micrometer-sized pores to be able to individually resolve suspending membranes by means of fluorescence microscopy. To be able to produce PSMs on pores that are micrometer in size, an orthogonal functionalization strategy resulting in a hydrophilic surface is highly desirable. Here, we report on a method to prepare PSMs based on the evaporation of a thin layer of silicon monoxide on top of the porous substrate. PM-IRRAS experiments demonstrate that the final surface is composed of SiOx with 1 < x < 2. The hydrophilic surface turned out to be well suited to spread giant unilamellar vesicles forming PSMs. As the method does not rely on a gold coating as frequently used for orthogonal functionalization, fluorescence micrographs provide information not only from the freestanding membrane areas but also from the supported ones. The observation of the entire PSM area enabled us to observe phase-separation in these membranes on the freestanding and supported parts as well as protein binding and possible lipid reorganization of the membranes induced by binding of the protein Shiga toxin.
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Affiliation(s)
- Nelli Teske
- Institute of Organic and Biomolecular Chemistry, University of Göttingen , Tammannstraße 2, 37077 Göttingen, Germany
| | - Jeremias Sibold
- Institute of Organic and Biomolecular Chemistry, University of Göttingen , Tammannstraße 2, 37077 Göttingen, Germany
| | - Johannes Schumacher
- Institute of Organic and Biomolecular Chemistry, University of Göttingen , Tammannstraße 2, 37077 Göttingen, Germany
| | - Nikolas K Teiwes
- Institute of Organic and Biomolecular Chemistry, University of Göttingen , Tammannstraße 2, 37077 Göttingen, Germany
| | - Martin Gleisner
- Institute of Organic and Biomolecular Chemistry, University of Göttingen , Tammannstraße 2, 37077 Göttingen, Germany
| | - Ingo Mey
- Institute of Organic and Biomolecular Chemistry, University of Göttingen , Tammannstraße 2, 37077 Göttingen, Germany
| | - Claudia Steinem
- Institute of Organic and Biomolecular Chemistry, University of Göttingen , Tammannstraße 2, 37077 Göttingen, Germany
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14
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Bhatia T, Cornelius F, Ipsen JH. Capturing suboptical dynamic structures in lipid bilayer patches formed from free-standing giant unilamellar vesicles. Nat Protoc 2017; 12:1563-1575. [DOI: 10.1038/nprot.2017.047] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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15
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Abstract
In the plasma membrane of eukaryotic cells, proteins and lipids are organized in clusters, the latter ones often called lipid domains or "lipid rafts." Recent findings highlight the dynamic nature of such domains and the key role of membrane geometry and spatial boundaries. In this study, we used porous substrates with different pore radii to address precisely the extent of the geometric constraint, permitting us to modulate and investigate the size and mobility of lipid domains in phase-separated continuous pore-spanning membranes (PSMs). Fluorescence video microscopy revealed two types of liquid-ordered (lo) domains in the freestanding parts of the PSMs: (i) immobile domains that were attached to the pore rims and (ii) mobile, round-shaped lo domains within the center of the PSMs. Analysis of the diffusion of the mobile lo domains by video microscopy and particle tracking showed that the domains' mobility is slowed down by orders of magnitude compared with the unrestricted case. We attribute the reduced mobility to the geometric confinement of the PSM, because the drag force is increased substantially due to hydrodynamic effects generated by the presence of these boundaries. Our system can serve as an experimental test bed for diffusion of 2D objects in confined geometry. The impact of hydrodynamics on the mobility of enclosed lipid domains can have great implications for the formation and lateral transport of signaling platforms.
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16
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Exploring the raft-hypothesis by probing planar bilayer patches of free-standing giant vesicles at nanoscale resolution, with and without Na,K-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:3041-3049. [DOI: 10.1016/j.bbamem.2016.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 08/06/2016] [Accepted: 09/01/2016] [Indexed: 12/26/2022]
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17
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Blosser MC, Honerkamp-Smith AR, Han T, Haataja M, Keller SL. Transbilayer Colocalization of Lipid Domains Explained via Measurement of Strong Coupling Parameters. Biophys J 2016; 109:2317-27. [PMID: 26636943 DOI: 10.1016/j.bpj.2015.10.031] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 10/16/2015] [Accepted: 10/26/2015] [Indexed: 01/03/2023] Open
Abstract
When micron-scale compositional heterogeneity develops in membranes, the distribution of lipids on one face of the membrane strongly affects the distribution on the other. Specifically, when lipid membranes phase separate into coexisting liquid phases, domains in each monolayer leaflet of the membrane are colocalized with domains in the opposite leaflet. Colocalized domains have never been observed to spontaneously move out of registry. This result indicates that the lipid compositions in one leaflet are strongly coupled to compositions in the opposing leaflet. Predictions of the interleaflet coupling parameter, Λ, vary by a factor of 50. We measure the value of Λ by applying high shear forces to supported lipid bilayers. This causes the upper leaflet to slide over the lower leaflet, moving domains out of registry. We find that the threshold shear stress required to deregister domains in the upper and lower leaflets increases with the inverse length of domains. We derive a simple, closed-form expression relating the threshold shear to Λ, and find Λ = 0.016 ± 0.004 kBT/nm2.
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Affiliation(s)
- Matthew C Blosser
- Departments of Chemistry and Physics, University of Washington, Seattle, Washington
| | - Aurelia R Honerkamp-Smith
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
| | - Tao Han
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey
| | - Mikko Haataja
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey
| | - Sarah L Keller
- Departments of Chemistry and Physics, University of Washington, Seattle, Washington.
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18
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Spatial distribution and activity of Na + /K + -ATPase in lipid bilayer membranes with phase boundaries. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1390-9. [DOI: 10.1016/j.bbamem.2016.03.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 02/20/2016] [Accepted: 03/10/2016] [Indexed: 11/21/2022]
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19
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Bleecker JV, Cox PA, Foster RN, Litz JP, Blosser MC, Castner DG, Keller SL. Thickness Mismatch of Coexisting Liquid Phases in Noncanonical Lipid Bilayers. J Phys Chem B 2016; 120:2761-70. [PMID: 26890258 DOI: 10.1021/acs.jpcb.5b10165] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Lipid composition dictates membrane thickness, which in turn can influence membrane protein activity. Lipid composition also determines whether a membrane demixes into coexisting liquid-crystalline phases. Previous direct measurements of demixed lipid membranes have always found a liquid-ordered phase that is thicker than the liquid-disordered phase. Here we investigated noncanonical ternary lipid mixtures designed to produce bilayers with thicker disordered phases than ordered phases. The membranes were composed of short, saturated (ordered) lipids; long, unsaturated (disordered) lipids; and cholesterol. We found that few of these systems yield coexisting liquid phases above 10 °C. For membranes that do demix into two liquid phases, we measured the thickness mismatch between the phases by atomic force microscopy and found that not one of the systems yields thicker disordered than ordered phases under standard experimental conditions. We found no monotonic relationship between demixing temperatures of these ternary systems and either estimated thickness mismatches between the liquid phases or the physical parameters of single-component membranes composed of the individual lipids. These results highlight the robustness of a membrane's liquid-ordered phase to be thicker than the liquid-disordered phase, regardless of the membrane's lipid composition.
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Affiliation(s)
- Joan V Bleecker
- Departments of Chemistry, ‡Chemical Engineering, and §Bioengineering, University of Washington , Seattle, Washington 98195, United States
| | - Phillip A Cox
- Departments of Chemistry, ‡Chemical Engineering, and §Bioengineering, University of Washington , Seattle, Washington 98195, United States
| | - Rami N Foster
- Departments of Chemistry, ‡Chemical Engineering, and §Bioengineering, University of Washington , Seattle, Washington 98195, United States
| | - Jonathan P Litz
- Departments of Chemistry, ‡Chemical Engineering, and §Bioengineering, University of Washington , Seattle, Washington 98195, United States
| | - Matthew C Blosser
- Departments of Chemistry, ‡Chemical Engineering, and §Bioengineering, University of Washington , Seattle, Washington 98195, United States
| | - David G Castner
- Departments of Chemistry, ‡Chemical Engineering, and §Bioengineering, University of Washington , Seattle, Washington 98195, United States
| | - Sarah L Keller
- Departments of Chemistry, ‡Chemical Engineering, and §Bioengineering, University of Washington , Seattle, Washington 98195, United States
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20
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Chang L, Hu J, Chen F, Chen Z, Shi J, Yang Z, Li Y, Lee LJ. Nanoscale bio-platforms for living cell interrogation: current status and future perspectives. NANOSCALE 2016; 8:3181-3206. [PMID: 26745513 DOI: 10.1039/c5nr06694h] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The living cell is a complex entity that dynamically responds to both intracellular and extracellular environments. Extensive efforts have been devoted to the understanding intracellular functions orchestrated with mRNAs and proteins in investigation of the fate of a single-cell, including proliferation, apoptosis, motility, differentiation and mutations. The rapid development of modern cellular analysis techniques (e.g. PCR, western blotting, immunochemistry, etc.) offers new opportunities in quantitative analysis of RNA/protein expression up to a single cell level. The recent entries of nanoscale platforms that include kinds of methodologies with high spatial and temporal resolution have been widely employed to probe the living cells. In this tutorial review paper, we give insight into background introduction and technical innovation of currently reported nanoscale platforms for living cell interrogation. These highlighted technologies are documented in details within four categories, including nano-biosensors for label-free detection of living cells, nanodevices for living cell probing by intracellular marker delivery, high-throughput platforms towards clinical current, and the progress of microscopic imaging platforms for cell/tissue tracking in vitro and in vivo. Perspectives for system improvement were also discussed to solve the limitations remains in current techniques, for the purpose of clinical use in future.
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Affiliation(s)
- Lingqian Chang
- NSF Nanoscale Science and Engineering Center (NSEC), The Ohio State University, Columbus, OH 43212, USA.
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21
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Barriga HMG, Law RV, Seddon JM, Ces O, Brooks NJ. The effect of hydrostatic pressure on model membrane domain composition and lateral compressibility. Phys Chem Chem Phys 2016; 18:149-55. [DOI: 10.1039/c5cp04239a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We distinguish the liquid ordered and liquid disordered phases in diffraction patterns of biphasic mixtures, comparing their lateral compressibility and report the variations in the two phase region with increasing hydrostatic pressure.
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Affiliation(s)
| | - R. V. Law
- Department of Chemistry
- Imperial College London
- UK
| | - J. M. Seddon
- Department of Chemistry
- Imperial College London
- UK
| | - O. Ces
- Department of Chemistry
- Imperial College London
- UK
| | - N. J. Brooks
- Department of Chemistry
- Imperial College London
- UK
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22
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Khadka NK, Ho CS, Pan J. Macroscopic and Nanoscopic Heterogeneous Structures in a Three-Component Lipid Bilayer Mixtures Determined by Atomic Force Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12417-12425. [PMID: 26506226 DOI: 10.1021/acs.langmuir.5b02863] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Much of lipid raft properties can be inferred from phase behavior of multicomponent lipid membranes. We use liquid compatible atomic force microscopy (AFM) to study a three-component system composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), egg sphingomyelin (eSM), and cholesterol. Specifically, we obtain macroscopic and nanoscopic heterogeneous structures in a broad compositional space of DOPC/eSM/cholesterol (23 °C). In the macroscopic liquid coexisting region, we quantify area fraction of the coexisting phases and determine a set of thermodynamic tie-lines. When lipid compositions are near the critical point, we obtain fluctuation-like nanoscopic structures. We also use AFM height images to explore the hypothetical three-phase coexisting region. Finally, we use fluorescence microscopy to compare the phase behavior from our AFM measurements to that in free-floating giant unilamellar vesicles (GUVs). Our results highlight the role of lipid composition in mediating lipid domain formation and stability.
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Affiliation(s)
- Nawal K Khadka
- Department of Physics, University of South Florida , Tampa, Florida 33620, United States
| | - Chian Sing Ho
- Department of Physics, University of South Florida , Tampa, Florida 33620, United States
| | - Jianjun Pan
- Department of Physics, University of South Florida , Tampa, Florida 33620, United States
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23
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Beddoes CM, Case CP, Briscoe WH. Understanding nanoparticle cellular entry: A physicochemical perspective. Adv Colloid Interface Sci 2015; 218:48-68. [PMID: 25708746 DOI: 10.1016/j.cis.2015.01.007] [Citation(s) in RCA: 220] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 01/21/2015] [Accepted: 01/22/2015] [Indexed: 12/21/2022]
Abstract
Understanding interactions between nanoparticles (NPs) with biological matter, particularly cells, is becoming increasingly important due to their growing application in medicine and materials, and consequent biological and environmental exposure. For NPs to be utilised to their full potential, it is important to correlate their functional characteristics with their physical properties, which may also be used to predict any adverse cellular responses. A key mechanism for NPs to impart toxicity is to gain cellular entry directly. Many parameters affect the behaviour of nanomaterials in a cellular environment particularly their interactions with cell membranes, including their size, shape and surface chemistry as well as factors such as the cell type, location and external environment (e.g. other surrounding materials, temperature, pH and pressure). Aside from in vitro and in vivo experiments, model cell membrane systems have been used in both computer simulations and physicochemical experiments to elucidate the mechanisms for NP cellular entry. Here we present a brief overview of the effects of NPs physical parameters on their cellular uptake, with focuses on 1) related research using model membrane systems and physicochemical methodologies; and 2) proposed physical mechanisms for NP cellular entrance, with implications to their nanotoxicity. We conclude with a suggestion that the energetic process of NP cellular entry can be evaluated by studying the effects of NPs on lipid mesophase transitions, as the molecular deformations and thus the elastic energy cost are analogous between such transitions and endocytosis. This presents an opportunity for contributions to understanding nanotoxicity from a physicochemical perspective.
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Affiliation(s)
- Charlotte M Beddoes
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK; Bristol Centre for Functional Nanomaterials, Centre for Nanoscience and Quantum Information, University of Bristol, UK
| | - C Patrick Case
- Musculoskeletal Research Unit, Clinical Science at North Bristol, University of Bristol, Avon Orthopaedic Centre, Southmead Hospital, Bristol BS10 5NB, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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24
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Abstract
All biological membranes consist of a complex composite of macromolecules and macromolecular assemblies, of which the fluid lipid-bilayer component is a core element with regard to cell encapsulation and barrier properties. The fluid lipid bilayer also supports the functional machinery of receptors, channels and pumps that are associated with the membrane. This bilayer is stabilized by weak physical and colloidal forces, and its nature is that of a self-assembled system of amphiphiles in water. Being only approximately 5 nm in thickness and still encapsulating a cell that is three orders of magnitude larger in diameter, the lipid bilayer as a material has very unusual physical properties, both in terms of structure and dynamics. Although the lipid bilayer is a fluid, it has a distinct and structured trans-bilayer profile, and in the plane of the bilayer the various molecular components, viz different lipid species and membrane proteins, have the capacity to organize laterally in terms of differentiated domains on different length and time scales. These elements of small-scale structure and order are crucial for the functioning of the membrane. It has turned out to be difficult to quantitatively study the small-scale structure of biological membranes. A major part of the insight into membrane micro- and nano-domains and the concepts used to describe them have hence come from studies of simple lipid bilayers as models of membranes, by use of a wide range of theoretical, experimental and simulational approaches. Many questions remain to be answered as to which extent the result from model studies can carry over to real biological membranes.
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25
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Sacchi M, Balleza D, Vena G, Puia G, Facci P, Alessandrini A. Effect of neurosteroids on a model lipid bilayer including cholesterol: An Atomic Force Microscopy study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1258-67. [PMID: 25620773 DOI: 10.1016/j.bbamem.2015.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 12/18/2014] [Accepted: 01/02/2015] [Indexed: 12/20/2022]
Abstract
Amphiphilic molecules which have a biological effect on specific membrane proteins, could also affect lipid bilayer properties possibly resulting in a modulation of the overall membrane behavior. In light of this consideration, it is important to study the possible effects of amphiphilic molecule of pharmacological interest on model systems which recapitulate some of the main properties of the biological plasma membranes. In this work we studied the effect of a neurosteroid, Allopregnanolone (3α,5α-tetrahydroprogesterone or Allo), on a model bilayer composed by the ternary lipid mixture DOPC/bSM/chol. We chose ternary mixtures which present, at room temperature, a phase coexistence of liquid ordered (Lo) and liquid disordered (Ld) domains and which reside near to a critical point. We found that Allo, which is able to strongly partition in the lipid bilayer, induces a marked increase in the bilayer area and modifies the relative proportion of the two phases favoring the Ld phase. We also found that the neurosteroid shifts the miscibility temperature to higher values in a way similarly to what happens when the cholesterol concentration is decreased. Interestingly, an isoform of Allo, isoAllopregnanolone (3β,5α-tetrahydroprogesterone or isoAllo), known to inhibit the effects of Allo on GABAA receptors, has an opposite effect on the bilayer properties.
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Affiliation(s)
- Mattia Sacchi
- Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Via Campi 213/A, 41125 Modena, Italy; CNR - Istituto Nanoscienze, S3, Via Campi 213/A, 41125 Modena, Italy
| | - Daniel Balleza
- CNR - Istituto Nanoscienze, S3, Via Campi 213/A, 41125 Modena, Italy
| | - Giulia Vena
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via Campi 287, Modena 287, Italy
| | - Giulia Puia
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via Campi 287, Modena 287, Italy
| | - Paolo Facci
- CNR - Istituto di Biofisica, Via De Marini 6, 16149 Genova, Italy
| | - Andrea Alessandrini
- Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Via Campi 213/A, 41125 Modena, Italy; CNR - Istituto Nanoscienze, S3, Via Campi 213/A, 41125 Modena, Italy.
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26
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Alessandrini A, Facci P. Phase transitions in supported lipid bilayers studied by AFM. SOFT MATTER 2014; 10:7145-7164. [PMID: 25090108 DOI: 10.1039/c4sm01104j] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We review the capabilities of Atomic Force Microscopy (AFM) in the study of phase transitions in Supported Lipid Bilayers (SLBs). AFM represents a powerful technique to cover the resolution range not available to fluorescence imaging techniques and where spectroscopic data suggest what the relevant lateral scale for domain formation might be. Phase transitions of lipid bilayers involve the formation of domains characterized by different heights with respect to the surrounding phase and are therefore easily identified by AFM in liquid solution once the bilayer is confined to a flat surface. Even if not endowed with high time resolution, AFM allows light to be shed on some aspects related to lipid phase transitions in the case of both a single lipid component and lipid mixtures containing sterols also. We discuss here the obtained results in light of the peculiarities of supported lipid bilayer model systems.
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Affiliation(s)
- Andrea Alessandrini
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Via Campi 213/A, 41125, Modena, Italy.
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