1
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Wagner AM, Quandt J, Söder D, Garay‐Sarmiento M, Joseph A, Petrovskii VS, Witzdam L, Hammoor T, Steitz P, Haraszti T, Potemkin II, Kostina NY, Herrmann A, Rodriguez‐Emmenegger C. Ionic Combisomes: A New Class of Biomimetic Vesicles to Fuse with Life. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200617. [PMID: 35393756 PMCID: PMC9189634 DOI: 10.1002/advs.202200617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/03/2022] [Indexed: 06/14/2023]
Abstract
The construction of biomembranes that faithfully capture the properties and dynamic functions of cell membranes remains a challenge in the development of synthetic cells and their application. Here a new concept for synthetic cell membranes based on the self-assembly of amphiphilic comb polymers into vesicles, termed ionic combisomes (i-combisomes) is introduced. These combs consist of a polyzwitterionic backbone to which hydrophobic tails are linked by electrostatic interactions. Using a range of microscopies and molecular simulations, the self-assembly of a library of combs in water is screened. It is discovered that the hydrophobic tails form the membrane's core and force the backbone into a rod conformation with nematic-like ordering confined to the interface with water. This particular organization resulted in membranes that combine the stability of classic polymersomes with the biomimetic thickness, flexibility, and lateral mobility of liposomes. Such unparalleled matching of biophysical properties and the ability to locally reconfigure the molecular topology of its constituents enable the harboring of functional components of natural membranes and fusion with living bacteria to "hijack" their periphery. This provides an almost inexhaustible palette to design the chemical and biological makeup of the i-combisomes membrane resulting in a powerful platform for fundamental studies and technological applications.
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Affiliation(s)
- Anna M. Wagner
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Jonas Quandt
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Dominik Söder
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Manuela Garay‐Sarmiento
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Chair of BiotechnologyRWTH Aachen UniversityWorringerweg 3Aachen52074Germany
| | - Anton Joseph
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Vladislav S. Petrovskii
- Physics DepartmentLomonosov Moscow State UniversityLeninskie Gory 1–2Moscow119991Russian Federation
| | - Lena Witzdam
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Thomas Hammoor
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
| | - Philipp Steitz
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
| | - Tamás Haraszti
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
| | - Igor I. Potemkin
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Physics DepartmentLomonosov Moscow State UniversityLeninskie Gory 1–2Moscow119991Russian Federation
- National Research, South Ural State UniversityChelyabinsk454080Russian Federation
| | - Nina Yu. Kostina
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Andreas Herrmann
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Cesar Rodriguez‐Emmenegger
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute for Bioengineering of Catalonia (IBEC)Carrer de Baldiri Reixac, 10, 12Barcelona08028Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA)Passeig Lluís Companys 23Barcelona08010Spain
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2
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Berganza E, Hirtz M. Direct-Write Patterning of Biomimetic Lipid Membranes In Situ with FluidFM. ACS APPLIED MATERIALS & INTERFACES 2021; 13:50774-50784. [PMID: 34677057 DOI: 10.1021/acsami.1c15166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The creation of biologically inspired artificial membranes on substrates with custom size and in close proximity to each other not only provides a platform to study biological processes in a simplified manner, but they also constitute building blocks for chemical or biological sensors integrated in microfluidic devices. Scanning probe lithography tools such as dip-pen nanolithography (DPN) have opened a new paradigm in this regard, although they possess some inherent drawbacks like the need to operate in air environment or the limited choice of lipids that can be patterned. In this work, we propose the use of the fluid force microscopy (FluidFM) technology to fabricate biomimetic membranes without losing the multiplexing capability of DPN but gaining flexibility in lipid inks and patterning environment. We shed light on the driving mechanisms of the FluidFM-mediated lithography processes in air and liquid. The obtained results should prompt the creation of more realistic biomimetic membranes with arbitrary complex phospholipid mixtures, cholesterol, and potential functional membrane proteins directly patterned in physiological environment.
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Affiliation(s)
- Eider Berganza
- Institute of Nanotechnology (INT) & Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Michael Hirtz
- Institute of Nanotechnology (INT) & Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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3
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Kostina NY, Wagner AM, Haraszti T, Rahimi K, Xiao Q, Klein ML, Percec V, Rodriguez-Emmenegger C. Unraveling topology-induced shape transformations in dendrimersomes. SOFT MATTER 2021; 17:254-267. [PMID: 32789415 DOI: 10.1039/d0sm01097a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The vital functions of cell membranes require their ability to quickly change shape to perform complex tasks such as motion, division, endocytosis, and apoptosis. Membrane curvature in cells is modulated by very complex processes such as changes in lipid composition, the oligomerization of curvature-scaffolding proteins, and the reversible insertion of protein regions that act like wedges in the membrane. But, could much simpler mechanisms support membrane shape transformation? In this work, we demonstrate how the change of amphiphile topology in the bilayer can drive shape transformations of cell membrane models. To tackle this, we have designed and synthesized new types of amphiphiles-Janus dendrimers-that self-assemble into uni-, multilamellar, or smectic-ordered vesicles, named dendrimersomes. We synthesized Janus dendrimers containing a photo-labile bond that upon UV-Vis irradiation cleavage lose a part of the hydrophilic dendron. This leads to a change from a cylindrically to a wedge-shaped amphiphile. The high mobility of these dendrimers allows for the concentration of the wedge-shaped amphiphiles and the generation of transmembrane asymmetries. The concentration of the wedges and their rate of segregation allowed control of the budding and generation of structures such as tubules and high genus vesicles.
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Affiliation(s)
- Nina Yu Kostina
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
| | - Anna M Wagner
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
| | - Tamás Haraszti
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
| | - Khosrow Rahimi
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
| | - Qi Xiao
- Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA and Institute of Computational Molecular Science, Temple University, Philadelphia, PA 19122, USA
| | - Michael L Klein
- Institute of Computational Molecular Science, Temple University, Philadelphia, PA 19122, USA
| | - Virgil Percec
- Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA
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4
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Redeker C, Briscoe WH. Interactions between Mutant Bacterial Lipopolysaccharide (LPS-Ra) Surface Layers: Surface Vesicles, Membrane Fusion, and Effect of Ca 2+and Temperature. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15739-15750. [PMID: 31604373 DOI: 10.1021/acs.langmuir.9b02609] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lipopolysaccharides (LPS) are a major component of the protective outer membrane of Gram-negative bacteria. Understanding how the solution conditions may affect LPS-containing membranes is important to optimizing the design of antibacterial agents (ABAs) which exploit electrostatic and hydrophobic interactions to disrupt the bacteria membrane. Here, interactions between surface layers of LPS (Ra mutants) in aqueous media have been studied using a surface force apparatus (SFA), exploring the effects of temperature and divalent Ca2+ cations. Complementary dynamic light scattering (DLS) characterization suggests that vesicle-like aggregates of diameter ∼28-80 nm are formed by LPS-Ra in aqueous media. SFA results show that LPS-Ra vesicles adsorb weakly onto mica in pure water at room temperature (RT) and the surface layers are readily squeezed out as the two surfaces approach each other. However, upon addition of calcium (Ca2+) cations at near physiological concentration (2.5 mM) at RT, LPS multilayers or deformed LPS liposomes on mica are observed, presumably due to bridging between LPS phosphate groups and between LPS phosphates and negatively charged mica mediated by Ca2+, with a hard wall repulsion at surface separation D0 ∼ 30-40 nm. At 40 °C, which is above the LPS-Ra β-α acyl chain melting temperature (Tm = 36 °C), fusion events between the surface layers under compression could be observed, evident from δD ∼ 8-10 nm steps in the force-distance profiles attributed to LPS-bilayers being squeezed out due to enhanced fluidity of the LPS acyl-chain, with a final hard wall surface separation D0 ∼ 8-10 nm corresponding to the thickness of a single bilayer confined between the surfaces. These unprecedented SFA results reveal intricate structural responses of LPS surface layers to temperature and Ca2+, with implications to our fundamental understanding of the structures and interactions of bacterial membranes.
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Affiliation(s)
- Christian Redeker
- School of Chemistry , University of Bristol , Cantock's Close, Bristol BS8 1TS , United Kingdom
| | - Wuge H Briscoe
- School of Chemistry , University of Bristol , Cantock's Close, Bristol BS8 1TS , United Kingdom
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5
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Cao Y, Kampf N, Klein J. Boundary Lubrication, Hemifusion, and Self-Healing of Binary Saturated and Monounsaturated Phosphatidylcholine Mixtures ⧫. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15459-15468. [PMID: 31296001 DOI: 10.1021/acs.langmuir.9b01660] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A wide range of phosphatidylcholine (PC) lipids with different degrees of unsaturation has been identified in the human synovial fluid and on the cartilage surface. The outstanding lubricity of the articular cartilage surface has been attributed to boundary layers comprising complexes of such lipids, though to date, only lubrication by single-component PC-lipid-based boundary layers has been investigated. As distinguishable lubrication behavior has been found to be related to the PC structures, we herein examined the surface morphology (on mica) and the lubrication ability of binary PC lipid mixtures, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), using atomic force microscopy (AFM) and a surface force balance (SFB). These two PC lipids are among the most abundant saturated and unsaturated PC components in synovial joints. Small unilamellar vesicles (SUVs) prepared from DPPC-POPC mixtures (8:2, 5:5, and 2:8, molar ratios) ruptured and formed bilayers on mica. The normal and shear forces between two DPPC-POPC bilayer-coated mica surfaces across the corresponding SUV dispersions show good boundary lubrication (friction coefficients ≤ ca. 10-4) up to contact stresses of 8.3 ± 2.2 MPa for 8:2 DPPC-POPC and 5.0 ± 1.7 MPa for the others. Hemifusion induced at high normal pressures was observed, probably because of the height mismatch of two components. Reproducible successive approaches after hemifusion indicate rapid self-healing of the mica-supported bilayers in the presence of the SUVs reservoir. This work is a first step to provide insight concerning the lubrication, wear, and healing of the PC-based boundary layers, which must consist of multicomponent lipid mixtures, on the articular cartilage surface.
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Affiliation(s)
- Yifeng Cao
- Department of Materials and Interfaces , Weizmann Institute of Science , Rehovot 76100 , Israel
| | - Nir Kampf
- Department of Materials and Interfaces , Weizmann Institute of Science , Rehovot 76100 , Israel
| | - Jacob Klein
- Department of Materials and Interfaces , Weizmann Institute of Science , Rehovot 76100 , Israel
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6
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Leivers M, Seddon JM, Declercq M, Robles E, Luckham P. Measurement of Forces between Supported Cationic Bilayers by Colloid Probe Atomic Force Microscopy: Electrolyte Concentration and Composition. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:729-738. [PMID: 30562468 DOI: 10.1021/acs.langmuir.8b03555] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The interactions between supported cationic surfactant bilayers were measured by colloidal probe atomic force spectroscopy, and the effect of different halide salts was investigated. Di(alkylisopropylester)dimethylammonium methylsulfate (DIPEDMAMS) bilayers were fabricated by the vesicle fusion technique on muscovite mica. The interactions between the bilayers were measured in increasing concentrations of NaCl, NaBr, NaI, and CaCl2. In NaCl, the bilayer interactions were repulsive at all concentrations investigated, and the Debye length and surface potential were observed to decrease with increasing concentration. The interactions were found to follow the electrical double layer (EDL) component of DLVO theory well. However, van der Waals forces were not detected; instead, a strong hydration repulsion was observed at short separations. CaCl2 had a similar effect on the interactions as NaCl. NaBr and NaI were observed to be more efficient at decreasing surface potential than the chloride salts, with the efficacy increasing with the ionic radius.
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Affiliation(s)
- Matthew Leivers
- Department of Chemistry , Imperial College London , London SW7 2AZ , United Kingdom
- Department of Chemical Engineering , Imperial College London , London SW7 2AZ , United Kingdom
| | - John M Seddon
- Department of Chemistry , Imperial College London , London SW7 2AZ , United Kingdom
| | - Marc Declercq
- The Procter & Gamble Company, Brussels Innovation Center , 1853 Strombeek Bever Temselaan 100 , 1853 Grimbergen , Belgium
| | - Eric Robles
- The Procter & Gamble Company, Newcastle Innovation Center , Whitley Road , Longbenton, Newcastle-Upon-Tyne NE12 9TS , United Kingdom
| | - Paul Luckham
- Department of Chemical Engineering , Imperial College London , London SW7 2AZ , United Kingdom
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7
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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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8
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Volkova AV, Ermakova LE, Golikova EV. Peculiarities of coagulation of the pseudohydrophilic colloids: Aggregate stability of the positively charged γ-Al2O3 hydrosol in NaCl solutions. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2016.12.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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9
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Briscoe WH. Aqueous boundary lubrication: Molecular mechanisms, design strategy, and terra incognita. Curr Opin Colloid Interface Sci 2017. [DOI: 10.1016/j.cocis.2016.09.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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10
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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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11
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Kim H, Lee KY, Ryu SR, Jung KH, Ahn TK, Lee Y, Kwon OS, Park SJ, Parker KK, Shin K. Charge-selective membrane protein patterning with proteoliposomes. RSC Adv 2015. [DOI: 10.1039/c4ra12088d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A novel method to fabricate transmembrane protein (TP) embedded lipid bilayers has been developed, resulting in an immobilized, but biologically functioning TP embedded lipid layer precisely in the targeted patterns.
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Affiliation(s)
- Heesuk Kim
- Institute of Biological Interfaces & Department of Chemistry
- Sogang University
- Seoul
- South Korea
| | - Keel Yong Lee
- Institute of Biological Interfaces & Department of Chemistry
- Sogang University
- Seoul
- South Korea
- Department of Energy Science
| | - Soo Ryeon Ryu
- Institute of Biological Interfaces & Department of Chemistry
- Sogang University
- Seoul
- South Korea
| | | | - Tae Kyu Ahn
- Department of Energy Science
- Sungkyunkwan University
- Suwon
- South Korea
| | - Yeonhee Lee
- Advanced Analysis Center
- Korea Institute of Science & Technology
- Seoul
- South Korea
| | - Oh-Sun Kwon
- Institute of Biological Interfaces & Department of Chemistry
- Sogang University
- Seoul
- South Korea
| | - Sung-Jin Park
- School of Engineering and Applied Sciences
- Harvard University
- Cambridge
- USA
| | - Kevin Kit Parker
- School of Engineering and Applied Sciences
- Harvard University
- Cambridge
- USA
| | - Kwanwoo Shin
- Institute of Biological Interfaces & Department of Chemistry
- Sogang University
- Seoul
- South Korea
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12
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Britton J, Cousens NEA, Coles S, van Engers CD, Babenko V, Murdock AT, Koós A, Perkin S, Grobert N. A graphene surface force balance. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:11485-92. [PMID: 25171130 PMCID: PMC4386928 DOI: 10.1021/la5028493] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 08/26/2014] [Indexed: 05/06/2023]
Abstract
We report a method for transferring graphene, grown by chemical vapor deposition, which produces ultraflat graphene surfaces (root-mean-square roughness of 0.19 nm) free from polymer residues over macroscopic areas (>1 cm(2)). The critical step in preparing such surfaces involves the use of an intermediate mica template, which itself is atomically smooth. We demonstrate the compatibility of these model surfaces with the surface force balance, opening up the possibility of measuring normal and lateral forces, including friction and adhesion, between two graphene sheets either in contact or across a liquid medium. The conductivity of the graphene surfaces allows forces to be measured while controlling the surface potential. This new apparatus, the graphene surface force balance, is expected to be of importance to the future understanding of graphene in applications from lubrication to electrochemical energy storage systems.
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Affiliation(s)
- Jude Britton
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United
Kingdom
| | - Nico E. A. Cousens
- Department
of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Samuel
W. Coles
- Department
of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | | | - Vitaliy Babenko
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United
Kingdom
| | - Adrian T. Murdock
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United
Kingdom
| | - Antal Koós
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United
Kingdom
| | - Susan Perkin
- Department
of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Nicole Grobert
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United
Kingdom
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13
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Toca-Herrera JL, Krasteva N, Müller HJ, Krastev R. Interactions in lipid stabilised foam films. Adv Colloid Interface Sci 2014; 207:93-106. [PMID: 24641908 DOI: 10.1016/j.cis.2014.02.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2013] [Revised: 02/13/2014] [Accepted: 02/15/2014] [Indexed: 11/30/2022]
Abstract
The interaction between lipid bilayers in water has been intensively studied over the last decades. Osmotic stress was applied to evaluate the forces between two approaching lipid bilayers in aqueous solution. The force-distance relation between lipid mono- or bilayers deposited on mica sheets using a surface force apparatus (SFA) was also measured. Lipid stabilised foam films offer another possibility to study the interactions between lipid monolayers. These films can be prepared comparatively easy with very good reproducibility. Foam films consist usually of two adsorbed surfactant monolayers separated by a layer of the aqueous solution from which the film is created. Their thickness can be conveniently measured using microinterferometric techniques. Studies with foam films deliver valuable information on the interactions between lipid membranes and especially their stability and permeability. Presenting inverse black lipid membrane (BLM) foam films supply information about the properties of the lipid self-organisation in bilayers. The present paper summarises results on microscopic lipid stabilised foam films by measuring their thickness and contact angle. Most of the presented results concern foam films prepared from dispersions of the zwitterionic lipid 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) and some of its mixtures with the anionic lipid -- 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG). The strength of the long range and short range forces between the lipid layers is discussed. The van der Waals attractive force is calculated. The electrostatic repulsive force is estimated from experiments at different electrolyte concentrations (NaCl, CaCl₂) or by modification of the electrostatic double layer surface potential by incorporating charged lipids in the lipid monolayers. The short range interactions are studied and modified by using small carbohydrates (fructose and sucrose), ethanol (EtOH) or dimethylsulfoxide (DMSO). Some results are compared with the structure of lipid monolayers deposited at the liquid/air interface (monolayers spread in Langmuir trough), which are one of most studied biomembrane model system. The comparison between the film thickness and the free energy of film formation is used to estimate the contribution of the different components of the disjoining pressure to the total interaction in the film and their dependence on the composition of the film forming solution.
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Affiliation(s)
- José Luis Toca-Herrera
- Institute for Biophysics, Department of Nanobiotechnology, University of Natural Resources and Life Sciences Vienna (BOKU), Muthgasse 11, Vienna, Austria
| | | | - Hans-Joachim Müller
- Max-Planck Institute of Colloids and Interfaces, 14424 Golm/Potsdam, Germany
| | - Rumen Krastev
- NMI Natural and Medical Sciences Institute at the University of Tübingen, 72770 Reutlingen, Germany; School of Applied Chemistry, Reutlingen University, 72762 Reutlingen, Germany.
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14
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Garvey CJ, Lenné T, Koster KL, Kent B, Bryant G. Phospholipid membrane protection by sugar molecules during dehydration-insights into molecular mechanisms using scattering techniques. Int J Mol Sci 2013; 14:8148-63. [PMID: 23584028 PMCID: PMC3645735 DOI: 10.3390/ijms14048148] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 04/03/2013] [Accepted: 04/09/2013] [Indexed: 11/17/2022] Open
Abstract
Scattering techniques have played a key role in our understanding of the structure and function of phospholipid membranes. These techniques have been applied widely to study how different molecules (e.g., cholesterol) can affect phospholipid membrane structure. However, there has been much less attention paid to the effects of molecules that remain in the aqueous phase. One important example is the role played by small solutes, particularly sugars, in protecting phospholipid membranes during drying or slow freezing. In this paper, we present new results and a general methodology, which illustrate how contrast variation small angle neutron scattering (SANS) and synchrotron-based X-ray scattering (small angle (SAXS) and wide angle (WAXS)) can be used to quantitatively understand the interactions between solutes and phospholipids. Specifically, we show the assignment of lipid phases with synchrotron SAXS and explain how SANS reveals the exclusion of sugars from the aqueous region in the particular example of hexagonal II phases formed by phospholipids.
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Affiliation(s)
- Christopher J. Garvey
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Australia; E-Mail:
| | - Thomas Lenné
- Research School of Biological Sciences, the Australian National University, Canberra, ACT 0200, Australia; E-Mail:
| | - Karen L. Koster
- Department of Biology, The University of South Dakota, Vermillion, SD 57069, USA; E-Mail:
| | - Ben Kent
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Australia; E-Mail:
| | - Gary Bryant
- School of Applied Sciences, RMIT University, Melbourne, VIC 3001, Australia; E-Mail:
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Morandat S, Azouzi S, Beauvais E, Mastouri A, El Kirat K. Atomic force microscopy of model lipid membranes. Anal Bioanal Chem 2012; 405:1445-61. [DOI: 10.1007/s00216-012-6383-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Revised: 08/02/2012] [Accepted: 08/24/2012] [Indexed: 10/27/2022]
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16
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General hydrophobic interaction potential for surfactant/lipid bilayers from direct force measurements between light-modulated bilayers. Proc Natl Acad Sci U S A 2011; 108:15699-704. [PMID: 21896718 DOI: 10.1073/pnas.1112411108] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We establish and quantify correlations among the molecular structures, interaction forces, and physical processes associated with light-responsive self-assembled surfactant monolayers or bilayers at interfaces. Using the surface forces apparatus (SFA), the interaction forces between adsorbed monolayers and bilayers of an azobenzene-functionalized surfactant can be drastically and controllably altered by light-induced conversion of trans and cis molecular conformations. These reversible conformation changes affect significantly the shape of the molecules, especially in the hydrophobic region, which induces dramatic transformations of molecular packing in self-assembled structures, causing corresponding modulation of electrostatic double layer, steric hydration, and hydrophobic interactions. For bilayers, the isomerization from trans to cis exposes more hydrophobic groups, making the cis bilayers more hydrophobic, which lowers the activation energy barrier for (hemi)fusion. A quantitative and general model is derived for the interaction potential of charged bilayers that includes the electrostatic double-layer force of the Derjaguin-Landau-Verwey-Overbeek theory, attractive hydrophobic interactions, and repulsive steric-hydration forces. The model quantitatively accounts for the elastic strains, deformations, long-range forces, energy maxima, adhesion minima, as well as the instability (when it exists) as two bilayers breakthrough and (hemi)fuse. These results have several important implications, including quantitative and qualitative understanding of the hydrophobic interaction, which is furthermore shown to be a nonadditive interaction.
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Helm CA, Israelachvili JN. The role of the hydrophobic force in bilayer adhesion and fusion. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.19910460163] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Anderson TH, Donaldson SH, Zeng H, Israelachvili JN. Direct measurement of double-layer, van der Waals, and polymer depletion attraction forces between supported cationic bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:14458-14465. [PMID: 20735021 DOI: 10.1021/la1020687] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The interactions of supported cationic surfactant bilayers and the effects of nonadsorbing cationic polyelectrolytes on these interactions were studied using the surface forces apparatus (SFA) technique. Bilayers of the cationic surfactant di(tallow ethyl ester) dimethyl ammonium chloride (DEEDMAC) were deposited on mica surfaces using the Langmuir-Blodgett technique, and the interactions between the bilayers were measured in various salt, nonionic polymer (PEG), and cationic polyelectrolyte solutions at different polymer molecular weights and concentrations. The forces between the bilayers in CaCl(2) solution are purely repulsive and follow the DLVO theory quantitatively down to bilayer separations of ∼2 nm. Addition of nonadsorbing polymer or polyelectrolyte has a number of effects on the interactions including the induction of a depletion-attraction between the bilayers and screening of the double-layer repulsion due to the added ions in the solution from the polyelectrolyte. The experimental results are shown to agree well with standard theories of depletion attraction and double-layer screening associated with dissolved polyelectrolyte. We also observed significant time and rate effects on measuring the equilibrium bilayer-bilayer interactions possibly due to the unexpectedly long times (>1 min) associated with the charge regulation of the bilayer surfaces. Implications for the interactions and stability of vesicle dispersions, i.e., of free rather than supported bilayers, in polymer solutions are discussed.
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Affiliation(s)
- Travers H Anderson
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106-5080, USA
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El Kirat K, Morandat S, Dufrêne YF. Nanoscale analysis of supported lipid bilayers using atomic force microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:750-65. [DOI: 10.1016/j.bbamem.2009.07.026] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/17/2009] [Accepted: 07/23/2009] [Indexed: 12/11/2022]
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20
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Weirich KL, Israelachvili JN, Fygenson DK. Bilayer edges catalyze supported lipid bilayer formation. Biophys J 2010; 98:85-92. [PMID: 20085721 PMCID: PMC2800963 DOI: 10.1016/j.bpj.2009.09.050] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 09/18/2009] [Accepted: 09/24/2009] [Indexed: 11/30/2022] Open
Abstract
Supported lipid bilayers (SLB) are important for the study of membrane-based phenomena and as coatings for biosensors. Nevertheless, there is a fundamental lack of understanding of the process by which they form from vesicles in solution. We report insights into the mechanism of SLB formation by vesicle adsorption using temperature-controlled time-resolved fluorescence microscopy at low vesicle concentrations. First, lipid accumulates on the surface at a constant rate up to approximately 0.8 of SLB coverage. Then, as patches of SLB nucleate and spread, the rate of accumulation increases. At a coverage of approximately 1.5 x SLB, excess vesicles desorb as SLB patches rapidly coalesce into a continuous SLB. Variable surface fluorescence immediately before SLB patch formation argues against the existence of a critical vesicle density necessary for rupture. The accelerating rate of accumulation and the widespread, abrupt loss of vesicles coincide with the emergence and disappearance of patch edges. We conclude that SLB edges enhance vesicle adhesion to the surface and induce vesicle rupture, thus playing a key role in the formation of continuous SLB.
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Affiliation(s)
- Kimberly L. Weirich
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, California
| | - Jacob N. Israelachvili
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, California
- Chemical Engineering Department, University of California, Santa Barbara, California
| | - D. Kuchnir Fygenson
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, California
- Physics Department, University of California, Santa Barbara, California
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21
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22
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Pereira EMA, Kosaka PM, Rosa H, Vieira DB, Kawano Y, Petri DFS, Carmona-Ribeiro AM. Hybrid materials from intermolecular associations between cationic lipid and polymers. J Phys Chem B 2008; 112:9301-10. [PMID: 18630858 DOI: 10.1021/jp801297t] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Intermolecular associations between a cationic lipid and two model polymers were evaluated from preparation and characterization of hybrid thin films cast on silicon wafers. The novel materials were prepared by spin-coating of a chloroformic solution of lipid and polymer on silicon wafer. Polymers tested for miscibility with the cationic lipid dioctadecyldimethylammonium bromide (DODAB) were polystyrene (PS) and poly(methyl methacrylate) (PMMA). The films thus obtained were characterized by ellipsometry, wettability, optical and atomic force microscopy, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and activity against Escherichia coli. Whereas intermolecular ion-dipole interactions were available for the PMMA-DODAB interacting pair producing smooth PMMA-DODAB films, the absence of such interactions for PS-DODAB films caused lipid segregation, poor film stability (detachment from the silicon wafer) and large rugosity. In addition, the well-established but still remarkable antimicrobial DODAB properties were transferred to the novel hybrid PMMA/DODAB coating, which is demonstrated to be highly effective against E. coli.
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Affiliation(s)
- Edla M A Pereira
- Instituto de Química, Universidade de São Paulo, CP, Sãu Paulo SP, Brazil
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23
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Muir BW, Tarasova A, Gengenbach TR, Menzies DJ, Meagher L, Rovere F, Fairbrother A, McLean KM, Hartley PG. Characterization of low-fouling ethylene glycol containing plasma polymer films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:3828-3835. [PMID: 18307364 DOI: 10.1021/la702689t] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Low-protein-fouling poly(ethylene glycol) (PEG-like) plasma polymer films were prepared using radio frequency glow discharge polymerization of diethylene glycol dimethyl ether (DGpp) on top of a heptylamine plasma polymer primer layer. By varying the plasma deposition conditions, the chemistry of the DGpp film was influenced, especially in regard to the level of ether content, which in turn influenced the relative levels of bovine serum albumin and lysozyme protein fouling. Surface potential measurements indicated that these surfaces carried a net negative charge. While protein fouling remained low ( approximately 10 ng/cm2), there was a slightly higher level of the positively charged protein adsorbed on these films than the negative protein. The interaction forces measured between a silica spherical surface on both "high"- and "low"-protein-fouling DGpp films were all repulsive and short ranged (2-3 nm). There was no correlation between the surface forces measured for high- and low-protein-fouling DGpp films. Thus, it appears that enthalpic effects are very important in reducing protein adsorption. We therefore conclude that it is the concentration of residual, ethylene glycol containing species that are the crucial parameter determining protein resistance due to a combination of both entropic and enthalpic effects.
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Affiliation(s)
- Benjamin W Muir
- CSIRO Molecular and Health Technologies, Bayview Avenue, Clayton 3168, Australia.
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24
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Brasseur R, Deleu M, Mingeot-Leclercq MP, Francius G, Dufrêne YF. Probing peptide–membrane interactions using AFM. SURF INTERFACE ANAL 2008. [DOI: 10.1002/sia.2682] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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25
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El Kirat K, Morandat S. Cholesterol modulation of membrane resistance to Triton X-100 explored by atomic force microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:2300-9. [PMID: 17560898 DOI: 10.1016/j.bbamem.2007.05.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Revised: 04/23/2007] [Accepted: 05/03/2007] [Indexed: 02/05/2023]
Abstract
Biomembranes are not homogeneous, they present a lateral segregation of lipids and proteins which leads to the formation of detergent-resistant domains, also called "rafts". These rafts are particularly enriched in sphingolipids and cholesterol. Despite the huge body of literature on raft insolubility in non-ionic detergents, the mechanisms governing their resistance at the nanometer scale still remain poorly documented. Herein, we report a real-time atomic force microscopy (AFM) study of model lipid bilayers exposed to Triton X-100 (TX-100) at different concentrations. Different kinds of supported bilayers were prepared with dioleoylphosphatidylcholine (DOPC), sphingomyelin (SM) and cholesterol (Chol). The DOPC/SM 1:1 (mol/mol) membrane served as the non-resistant control, and DOPC/SM/Chol 2:1:1 (mol/mol/mol) corresponded to the raft-mimicking composition. For all the lipid compositions tested, AFM imaging revealed that TX-100 immediately solubilized the DOPC fluid phase leaving resistant patches of membrane. For the DOPC/SM bilayers, the remaining SM-enriched patches were slowly perforated leaving crumbled features reminiscent of the initial domains. For the raft model mixture, no holes appeared in the remaining SM/Chol patches and some erosion occurred. This work provides new, nanoscale information on the biomembranes' resistance to the TX-100-mediated solubilization, and especially about the influence of Chol.
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Affiliation(s)
- Karim El Kirat
- Laboratoire de Biomécanique et Génie Biomédical, UMR-CNRS 6600, Université de Technologie de Compiègne, BP 20529, 60205 Compiègne Cedex, France
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26
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Abstract
This study investigated the fusion of apposing floating bilayers of egg L-alpha-phosphatidylcholine (egg PC) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine. Atomic force microscope measurements of fusion forces under different compression rates were acquired to reveal the energy landscape of the fusion process under varied lipid composition and temperature. Between compression rates of approximately 1000 and approximately 100,000 pN/s, applied forces in the range from approximately 100 to approximately 500 pN resulted in fusion of floating bilayers. Our atomic force microscope measurements indicated that one main energy barrier dominated the fusion process. The acquired dynamic force spectra were fit with a simple model based on the transition state theory with the assumption that the fusion activation potential is linear. A significant shift in the energy landscape was observed when bilayer fluidity and composition were modified, respectively, by temperature and different cholesterol concentrations (15% < or = chol < or = 25%). Such modifications resulted in a more than twofold increase in the width of the fusion energy barrier for egg PC and 1,2-dimyristoyl-sn-glycero-3-phosphocholine floating bilayers. The addition of 25% cholesterol to egg PC bilayers increased the activation energy by approximately 1.0 k(B)T compared with that of bilayers with egg PC alone. These results reveal that widening of the energy barrier and consequently reduction in its slope facilitated membrane fusion.
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Affiliation(s)
- Midhat H Abdulreda
- Department of Physiology & Biophysics, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
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27
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Sheikh KH, Christenson HK, Bushby RJ, Evans SD. A Model System To Study the Insertion of Cholesterol into a Phospholipid Monolayer. J Phys Chem B 2006; 111:379-86. [PMID: 17214489 DOI: 10.1021/jp0636423] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Colloidal probe atomic force microscopy (AFM) was used to study the interaction between a surface bearing tethered cholesterol groups and an egg phosphatidylcholine (egg-PC) monolayer. The cholesterol bearing surface was comprised of a mixed self-assembled monolayer comprised of O-cholesteryl N-(8'-mecapto-3',6'-dioxaoctyl)carbamate (CPEO3) molecules and beta-mercaptoethanol formed on a 20 mum diameter gold-coated silica particle. The egg-PC monolayer was adsorbed onto an octadecylthiol monolayer formed on template-stripped gold. The force between the surfaces, as a function of separation, was measured for surface concentrations of CPEO3 from 0 to 100 mol %. At all concentrations there was a long-range repulsive double-layer force due to weak surface charges. At surface concentrations of CPEO3 from 1 to 29 mol % the interaction on the approach of the surfaces showed a maximum in the repulsive force, followed by a small (2-5 nm) jump into a force minimum corresponding to adhesion of the surfaces. On separation, a normalized pull-off force of 1.0-1.6 mN m(-1) was measured. Over the same concentration range, the calculated interaction energy per CPEO3 molecule decreased from 1.1 +/- 0.2 kT to 0.04 kT. At surface concentrations of 35 mol % and above there was no reproducible adhesion between the cholesterol-bearing surface and the phospholipid monolayer. We attribute the occurrence of short-range attraction and adhesion in the 1-29 mol % regime to the insertion of (some) cholesterol groups into the phospholipid monolayer. At higher surface concentrations the efficiency of insertion is reduced due to steric effects. We discuss the experimental results in the light of the energetics of the insertion of a cholesterol molecule into a lipid bilayer.
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Affiliation(s)
- Khizar H Sheikh
- School of Physics and Astronomy and Centre for Self-Organising Molecular Systems, The University of Leeds, Leeds LS2 9JT, United Kingdom
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28
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El Kirat K, Burton I, Dupres V, Dufrene YF. Sample preparation procedures for biological atomic force microscopy. J Microsc 2005; 218:199-207. [PMID: 15958012 DOI: 10.1111/j.1365-2818.2005.01480.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Since the late 1980s, atomic force microscopy (AFM) has been increasingly used in biological sciences and it is now established as a versatile tool to address the structure, properties and functions of biological specimens. AFM is unique in that it provides three-dimensional images of biological structures, including biomolecules, lipid films, 2D protein crystals and cells, under physiological conditions and with unprecedented resolution. A crucial prerequisite for successful, reliable biological AFM is that the samples need to be well attached to a solid substrate using appropriate, nondestructive methods. In this review, we discuss common techniques for immobilizing biological specimens for AFM studies.
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Affiliation(s)
- K El Kirat
- Unité de chimie des interfaces, Université catholique de Louvain, Belgium
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29
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Nichols-Smith S, Kuhl T. Electrostatic interactions between model mitochondrial membranes. Colloids Surf B Biointerfaces 2005; 41:121-7. [PMID: 15737537 DOI: 10.1016/j.colsurfb.2004.11.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2003] [Revised: 11/01/2004] [Accepted: 11/01/2004] [Indexed: 10/26/2022]
Abstract
Lipids are very diverse in both their respective structures and functions; and cells exquisitely control membrane composition. One intriguing issue is the specific role of lipids in modulating the physical properties of membranes. Cardiolipin (CL) is a unique four-tailed, doubly negatively charged lipid found predominately within the inner mitochondrial membrane, and is thought to be influential in determining the inner mitochondrial membrane potential and permeability. To determine the role of cardiolipin in modulating the charge properties of membranes, this study investigated the electrostatic interactions between mixed cardiolipin and phosphatidylcholine bilayers as a function of cardiolipin concentration. For physiologically relevant concentrations of cardiolipin, the surface charge density of the membrane was found to increase linearly with increasing concentration of cardiolipin. However, only a fraction of the cardiolipin molecules predicted to carry a charge from pK-values were ionized. Clearly environmental factors, beyond that of pH, play a role in determining the charge of bilayers containing cardiolipin.
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Affiliation(s)
- Stephanie Nichols-Smith
- Department of Chemical Engineering and Materials Science, University of California, One Shields Avenue, Davis, CA 95616-5294, USA
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30
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Bryant G, Koster KL. Dehydration of solute–lipid systems: hydration forces analysis. Colloids Surf B Biointerfaces 2004; 35:73-9. [PMID: 15261039 DOI: 10.1016/j.colsurfb.2004.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Revised: 12/11/2003] [Accepted: 02/11/2004] [Indexed: 11/24/2022]
Abstract
Sorption isotherms were obtained for a range of lipid/sugar/water mixtures. These were analysed using a simple hydration forces formalism. The results demonstrate that this simple analysis can be used to estimate dehydration parameters for these relatively complex systems. This in turn provides some insight into the location and role of sugars in the hydration behaviour of lipid systems. The relevance of these results to the phase behaviour of lipid/sugar mixtures during dehydration are discussed.
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Affiliation(s)
- Gary Bryant
- Department of Applied Physics, RMIT University, GPO Box 2476V, Melbourne 3001, Vic., Australia.
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31
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Maeda N, Senden TJ, di Meglio JM. Micromanipulation of phospholipid bilayers by atomic force microscopy. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1564:165-72. [PMID: 12101009 DOI: 10.1016/s0005-2736(02)00443-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The molecular details of adhesion mechanics in phospholipid bilayers have been studied using atomic force microscopy (AFM). Under tension fused bilayers of dipalmitoylphosphatidylcholine (DPPC) yield to give non-distance dependent and discrete force plateaux of 45.4, 81.6 and 113+/-3.5 pN. This behaviour may persist over distances as great as 400 nm and suggests the stable formation of a cylindrical tube which bridges the bilayers on the two surfaces. The stability of this connective structure may have implications for the formation of pili and hence for the initial stage of bacterial conjugation. Dimyristoylphosphatidylcholine (DMPC) bilayers also exhibit force plateaux but with a much less pronounced quantization. Bilayers composed of egg PC, sterylamine and cholesterol stressed in a similar way show complex behaviour which can in part be explained using the models demonstrated in the pure lipids.
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Affiliation(s)
- Nobuo Maeda
- Department of Applied Mathematics, Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australia
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32
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Majewski J, Kuhl TL, Wong JY, Smith GS. X-ray and neutron surface scattering for studying lipid/polymer assemblies at the air-liquid and solid-liquid interfaces. J Biotechnol 2000; 74:207-31. [PMID: 11143798 DOI: 10.1016/s1389-0352(00)00011-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Simple mono- and bilayers, built of amphiphilic molecules and prepared at air-liquid or solid-liquid interfaces, can be used as models to study such effects as water penetration, hydrocarbon chain packing, and structural changes due to head group modification. In the paper, we will discuss neutron and X-ray reflectometry and grazing incidence X-ray diffraction techniques used to explore structures of such ultra-thin organic films in different environments. We will illustrate the use of these methods to characterize the morphologies of the following systems: (i) polyethylene glycol-modified distearoylphosphatidylethanolamine monolayers at air-liquid and solid-liquid interfaces; and (ii) assemblies of branched polyethyleneimine polymer and dimyristoylphophatidylcholine lipid at solid-liquid interfaces.
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Affiliation(s)
- J Majewski
- Manuel Lujan Jr. Neutron Scattering Center, LANSCE-12, MS H805, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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Wong JY, Majewski J, Seitz M, Park CK, Israelachvili JN, Smith GS. Polymer-cushioned bilayers. I. A structural study of various preparation methods using neutron reflectometry. Biophys J 1999; 77:1445-57. [PMID: 10465755 PMCID: PMC1300432 DOI: 10.1016/s0006-3495(99)76992-4] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This neutron reflectometry study evaluates the structures resulting from different methods of preparing polymer-cushioned lipid bilayers. Four different techniques to deposit a dimyristoylphosphatidylcholine (DMPC) bilayer onto a polyethylenimine (PEI)-coated quartz substrate were examined: 1) vesicle adsorption onto a previously dried polymer layer; 2) vesicle adsorption onto a bare substrate, followed by polymer adsorption; and 3, 4) Langmuir-Blodgett vertical deposition of a lipid monolayer spread over a polymer-containing subphase to form a polymer-supported lipid monolayer, followed by formation of the outer lipid monolayer by either 3) horizontal deposition of the lipid monolayer or 4) vesicle adsorption. We show that the initial conditions of the polymer layer are a critical factor for the successful formation of our desired structure, i.e., a continuous bilayer atop a hydrated PEI layer. Our desired structure was found for all methods investigated except the horizontal deposition. The interaction forces between these polymer-supported bilayers are investigated in a separate paper (Wong, J. Y., C. K. Park, M. Seitz, and J. Israelachvili. 1999. Biophys. J. 77:1458-1468), which indicate that the presence of the polymer cushion significantly alters the interaction potential. These polymer-supported bilayers could serve as model systems for the study of transmembrane proteins under conditions more closely mimicking real cellular membrane environments.
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Affiliation(s)
- J Y Wong
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA
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Wong JY, Park CK, Seitz M, Israelachvili J. Polymer-cushioned bilayers. II. An investigation of interaction forces and fusion using the surface forces apparatus. Biophys J 1999; 77:1458-68. [PMID: 10465756 PMCID: PMC1300433 DOI: 10.1016/s0006-3495(99)76993-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We have created phospholipid bilayers supported on soft polymer "cushions" which act as deformable substrates (see accompanying paper, Wong, J. Y., J. Majewski, M. Seitz, C. K. Park, J. N. Israelachvili, and G. S. Smith. 1999. Biophys. J. 77:1445-1457). In contrast to "solid-supported" membranes, such "soft-supported" membranes can exhibit more natural (higher) fluidity. Our bilayer system was constructed by adsorption of small unilamellar dimyristoylphosphatidylcholine (DMPC) vesicles onto polyethylenimine (PEI)-supported Langmuir-Blodgett lipid monolayers on mica. We used the surface forces apparatus (SFA) to investigate the long-range forces, adhesion, and fusion of two DMPC bilayers both above and below their main transition temperature (T(m) approximately 24 degrees C). Above T(m), hemi-fusion activation pressures of apposing bilayers were considerably smaller than for solid-supported bilayers, e.g., directly supported on mica. After separation, the bilayers naturally re-formed after short healing times. Also, for the first time, complete fusion of two fluid (liquid crystalline) phospholipid bilayers was observed in the SFA. Below T(m) (gel state), very high pressures were needed for hemi-fusion and the healing process became very slow. The presence of the polymer cushion significantly alters the interaction potential, e.g., long-range forces as well as fusion pressures, when compared to solid-supported systems. These fluid model membranes should allow the future study of integral membrane proteins under more physiological conditions.
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Affiliation(s)
- J Y Wong
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106 USA
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36
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Abstract
Membranes are often damaged by freezing and/or dehydration, and this damage may be reduced by solutes. In many cases, these phenomena can be explained by the physical behavior of membrane-solute-water systems. Both solutes and membranes reduce the freezing temperature of water, although their effects are not simply additive. The dehydration of membranes induces large mechanical stresses in the membranes. These stresses produce a range of physical deformations and changes in the phase behavior. These membrane stresses and strains are in general reduced by osmotic effects and possibly other effects of solutes-provided of course that the solutes can approach the membrane in question. Membrane stresses may also be affected by vitrification where this occurs between membranes. Many of the differences among the effects of different solutes can be explained by the differences in the crystallization, vitrification, volumetric, partitioning, and permeability properties of the solutes.
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Affiliation(s)
- J Wolfe
- School of Physics, The University of New South Wales, Sydney, 2052, Australia
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37
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Hui S, Kuhl T, Guo Y, Israelachvili J. Use of poly(ethylene glycol) to control cell aggregation and fusion. Colloids Surf B Biointerfaces 1999. [DOI: 10.1016/s0927-7765(99)00037-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Majewski J, Wong JY, Park CK, Seitz M, Israelachvili JN, Smith GS. Structural studies of polymer-cushioned lipid bilayers. Biophys J 1998; 75:2363-7. [PMID: 9788931 PMCID: PMC1299910 DOI: 10.1016/s0006-3495(98)77680-5] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The structure of softly supported polymer-cushioned lipid bilayers, prepared in two different ways at the quartz-solution interface, were determined using neutron reflectometry. The polymer cushion consisted of a thin layer of branched, cationic polyethyleneimine (PEI), and the bilayers were formed by adsorption of small unilamellar dimyristoylphosphatidylcholine (DMPC) vesicles. When vesicles were first allowed to adsorb to a bare quartz substrate, an almost perfect bilayer formed. When the polymer was then added to the aqueous solution, it appeared to diffuse beneath this bilayer, effectively lifting it from the substrate. In contrast, if the polymer layer is adsorbed first to the bare quartz substrate followed by addition of vesicles to the solution, there is very little interaction of the vesicles with the polymer layer, and the result is a complex structure most likely consisting of patchy multilayers or adsorbed vesicles.
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Affiliation(s)
- J Majewski
- Manuel Lujan, Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Yoon YH, Pope JM, Wolfe J. The effects of solutes on the freezing properties of and hydration forces in lipid lamellar phases. Biophys J 1998; 74:1949-65. [PMID: 9545055 PMCID: PMC1299537 DOI: 10.1016/s0006-3495(98)77903-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Quantitative deuterium nuclear magnetic resonance is used to study the freezing behavior of the water in phosphatidylcholine lamellar phases, and the effect upon it of dimethylsulfoxide (DMSO), sorbitol, sucrose, and trehalose. When sufficient solute is present, an isotropic phase of concentrated aqueous solution may coexist with the lamellar phase at freezing temperatures. We determine the composition of both unfrozen phases as a function of temperature by using the intensity of the calibrated free induction decay signal (FID). The presence of DMSO or sorbitol increases the hydration of the lamellar phase at all freezing temperatures studied, and the size of the increase in hydration is comparable to that expected from their purely osmotic effect. Sucrose and trehalose increase the hydration of the lamellar phase, but, at concentrations of several molal, the increase is less than that which their purely osmotic effect would be expected to produce. A possible explanation is that very high volume fractions of sucrose and trehalose disrupt the water structure and thus reduce the repulsive hydration interaction between membranes. Because of their osmotic effect, all of the solutes studied reduced the intramembrane mechanical stresses produced in lamellar phases by freezing. Sucrose and trehalose at high concentrations produce a greater reduction than do the other solutes.
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Affiliation(s)
- Y H Yoon
- School of Physics, University of New South Wales, Sydney, Australia
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Yoon YH, Pope J, Wolfe J. Freezing-induced hydration forces between phosphatidylcholine bilayers—the effect of osmotic pressure. Colloids Surf A Physicochem Eng Asp 1997. [DOI: 10.1016/s0927-7757(97)00060-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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41
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Rapuano R, Carmona-Ribeiro AM. Physical Adsorption of Bilayer Membranes on Silica. J Colloid Interface Sci 1997; 193:104-11. [PMID: 9299094 DOI: 10.1006/jcis.1997.5060] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Isotherms for adsorption of bilayer-forming synthetic amphiphiles or phospholipids from vesicles onto hydrophilic silica particles (Aerosil OX-50) are obtained over a range of experimental conditions. Phosphatidylcholine (PC), dipalmitoylphosphatidylcholine (DPPC), dihexadecylphosphate (DHP), and dioctadecyldimethylammonium bromide (DODAB) dispersed in 10 mM Tris, pH 7.4, as small unilamellar vesicles present affinities for silica following the sequence DODAB > DPPC > PC > DHP. Among these, only DHP adsorption is below that expected for one bilayer deposition. Interaction at 65degreesC for 1 h between DPPC (or, at 25degreesC, for PC) vesicles and silica efficiently leads to bilayer deposition at maximal adsorption, if Tris is the buffer used. Preliminary centrifugation of the PC or DPPC vesicle dispersion is necessary to prevent overestimated adsorption. PC affinity for silica and its deposition as a bilayer depend on the nature of buffer used being much higher for Tris than for Hepes at pH 7.4. Formation of ion pairs between protonated amino groups in Tris and silanol groups on silica may lead to Tris adsorption and an increase in density of -OH groups on the solid surface. Therefore, formation of cooperative hydrogen bridges between -P=O in the phosphatidyl of the phospholipid bilayer and the -OH groups of Tris adsorbed on silica increases PC affinity for silica in the presence of Tris. For Hepes as buffer, PC affinity for silica is much lower and no plateau indicative of bilayer deposition is observed in the adsorption isotherm. Stabilization of supported phospholipid bilayers on solid surfaces requires several cooperative hydrogen bridges between the phospholipid and the solid surface. DODAB adsorption was unaffected by vesicle age and physical state of the bilayer vesicle. Adsorption isotherms for DODAB are of the high-affinity type with a maximum indicative of competition between intervesicle interactions and DODAB deposition on silica. Stabilization of DODAB bilayer deposition requires surface charge densities on silica higher than -1 μC/cm2. Copyright 1997Academic Press
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Affiliation(s)
- R Rapuano
- Instituto de Quimica, Universidade de Sao Paulo, Sao Paulo, 05599-970, Brazil
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42
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Ramos-de-Souza E, Anteneodo C, Costa-Pinto NM, Bisch PM. Nonlinear Dynamics of Lipid Films under Electric Forces. J Colloid Interface Sci 1997; 187:313-26. [PMID: 9073403 DOI: 10.1006/jcis.1996.4702] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We study the dynamics and rupture of lipid films perturbed in the symmetric mode squeezing through an electrohydrodynamical approach. The lipid phase and the two surrounding aqueous phases are considered as incompressible Newtonian viscous fluids submitted to van der Waals, steric, and electric body forces. A nonlinear evolution equation for the film thickness, at the long-wavelength limit, is obtained for two symmetric cases: a film with equally charged surfaces with no potential drop and a neutral film submitted to an external electric field. At the long-wavelength limit, the electric term only influences the film evolution when the electric field inside the film is nonvanishing. We solve numerically, as an initial value problem with periodic boundary conditions, the nonlinear evolution equation. The rupture time is obtained and compared with analytical estimates. Sufficiently strong steric forces prevent the film from narrowing beyond a minimum thickness leading the film to a steady state different from the planar one consistently with the nonlinear analytical approach. The presence of a transmembrane electric potential destabilizes the perturbed film as predicted by the linear and nonlinear approaches; however, as expected, destabilization is not relevant at physiological values of the potential drop.
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Affiliation(s)
- E Ramos-de-Souza
- Instituto de Biofisica Carlos Chagas Filho, FRJ, CCS, sala G026, Cidade Universitaria, Ilha do Fundao, Rio de Janeiro, 21949-900, Brazil
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43
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Supported phospholipid membranes: comparison among different deposition methods for a phospholipid monolayer. J Electroanal Chem (Lausanne) 1996. [DOI: 10.1016/s0022-0728(96)04737-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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44
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45
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46
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Arnold K. Cation-Induced Vesicle Fusion Modulated by Polymers and Proteins. HANDBOOK OF BIOLOGICAL PHYSICS 1995. [DOI: 10.1016/s1383-8121(06)80012-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Abstract
Poly(ethylene glycol) (PEG) is used widely to mediate cell-cell fusion in the production of somatic cell hybrids and in the fusion injection of macromolecules into cultured cells from erythrocytes or liposomes. However, little is known about the mechanisms by which PEG induces fusion of cell membranes, making its use much more an art than a science. This article considers possible molecular events involved in biomembrane fusion and summarizes what we have learned about these in recent years from studies of fusion of well-defined model membranes. In addition, it recounts observations made over the past several years about the process of PEG-mediated fusion of model membranes. These observations have defined the process to an extent sufficient to allow us to propose a model for the molecular events involved in the process. It is suggested that dehydration leads to asymmetry in the lipid packing pressure in the two leaflets of the membrane bilayer leading to formation of a single bilayer septum at a point of close apposition of two membranes. The single bilayer septum then decays during formation of the initial fusion pore. Agents that enhance or alleviate the dehydration-induced asymmetric packing stress will favor or inhibit fusion. Although the proposed picture is consistent with much accumulated data, it is not yet proven; experiments must now be devised to test its details. Finally, the proposed model is discussed in terms of potential implications for the mechanisms available to a cell in controlling more complex in vivo cell fusion processes such as endocytosis, exocytosis, protein sorting/transport, and viral budding/infection.
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Affiliation(s)
- B R Lentz
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill 27599-7260
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48
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Affiliation(s)
- P F Luckham
- Dept. Chem. Eng. and Chem. Tech., Imperial College of Science, Technology and Medicine, London, UK
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49
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Wolfe J, Yan Z, Pope JM. Hydration forces and membrane stresses: cryobiological implications and a new technique for measurement. Biophys Chem 1994; 49:51-8. [PMID: 8130351 DOI: 10.1016/0301-4622(93)e0081-f] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Very large, repulsive forces are measured between various surfaces in water at separations of about a nanometer or less. These forces are important in cryobiology because extracellular freezing usually causes extreme osmotic dehydration of cells. This brings membranes and macromolecules into close approach, and imposes large, anisotropic stresses on them. It is therefore important to study these forces at freezing temperatures. We have studied the freezing and thawing behaviour of lamellar phases of egg yolk lecithin and D2O. Force-hydration and force-separation relations are obtained from the deuterium nuclear magnetic resonance signal as a function of temperature. From these measurements we estimate the magnitude of freezing-induced membrane stresses and discuss their effect on the response of cells and organelles to freezing and thawing.
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Affiliation(s)
- J Wolfe
- School of Physics, University of New South Wales, Kensington, Australia
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50
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Hydration of the organized molecular assembly of ionic surfactants as studied by vapor pressure and x-ray diffraction. Colloid Polym Sci 1993. [DOI: 10.1007/bf00657077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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