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Mielke S, Sorkin R, Klein J. Effect of cholesterol on the mechanical stability of gel-phase phospholipid bilayers studied by AFM force spectroscopy. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:77. [PMID: 37672138 DOI: 10.1140/epje/s10189-023-00338-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 08/24/2023] [Indexed: 09/07/2023]
Abstract
The remarkably low sliding friction of articular cartilage in the major joints such as hips and knees, which is crucial for its homeostasis and joint health, has been attributed to lipid bilayers forming lubricious boundary layers at its surface. The robustness of such layers, and thus their lubrication efficiency at joint pressures, depends on the lipids forming them, including cholesterol which is a ubiquitous component, and which may act to strengthen of weaken the bilayer. In this work, a systematic study using an atomic force microscope (AFM) was carried out to understand the effect of cholesterol on the nanomechanical stability of two saturated phospholipids, DSPC (1,2-distearoyl-sn-glycero-3-phosphatidlycholine) and DPPC (1,2-dipalmitoyl-sn-glycero- phosphatidylcholine), that differ in acyl chain lengths. Measurements were carried out both in water and in phosphate buffer solution (PBS). The nanomechanical stability of the lipid bilayers was quantitatively evaluated by measuring the breakthrough force needed to puncture the bilayer by the AFM tip. The molar fractions of cholesterol incorporated in the bilayers were 10% and 40%. We found that for both DSPC and DPPC, cholesterol significantly decreases the mechanical stability of the bilayers in solid-ordered (SO) phase. In accordance with the literature, the strengthening effect of salt on the lipid bilayers was also observed. For DPPC with 10 mol % cholesterol, the effect of tip properties and the experimental procedure parameters on the breakthrough forces were also studied. Tip radius (2-42 nm), material (Si, Si3N4, Au) and loading rate (40-1000 nm/s) were varied systematically. The values of the breakthrough forces measured were not significantly affected by any of these parameters, showing that the weakening effect of cholesterol does not result from such changes in experimental conditions. As we have previously demonstrated that mechanical robustness improves the tribological performance of lipid layers, this study helps to shed light on the mechanism of physiological lubrication. Nanoindentation of SDPC bilayers.
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Affiliation(s)
- Salomé Mielke
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, 76100, Rehovot, Israel
| | - Raya Sorkin
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 6997801, Tel Aviv, Israel.
| | - Jacob Klein
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, 76100, Rehovot, Israel.
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2
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Abou Karam P, Rosenhek‐Goldian I, Ziv T, Ben Ami Pilo H, Azuri I, Rivkin A, Kiper E, Rotkopf R, Cohen SR, Torrecilhas AC, Avinoam O, Rojas A, Morandi MI, Regev‐Rudzki N. Malaria parasites release vesicle subpopulations with signatures of different destinations. EMBO Rep 2022; 23:e54755. [PMID: 35642585 PMCID: PMC9253735 DOI: 10.15252/embr.202254755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/02/2022] [Accepted: 05/11/2022] [Indexed: 11/09/2022] Open
Abstract
Malaria is the most serious mosquito-borne parasitic disease, caused mainly by the intracellular parasite Plasmodium falciparum. The parasite invades human red blood cells and releases extracellular vesicles (EVs) to alter its host responses. It becomes clear that EVs are generally composed of sub-populations. Seeking to identify EV subpopulations, we subject malaria-derived EVs to size-separation analysis, using asymmetric flow field-flow fractionation. Multi-technique analysis reveals surprising characteristics: we identify two distinct EV subpopulations differing in size and protein content. Small EVs are enriched in complement-system proteins and large EVs in proteasome subunits. We then measure the membrane fusion abilities of each subpopulation with three types of host cellular membranes: plasma, late and early endosome. Remarkably, small EVs fuse to early endosome liposomes at significantly greater levels than large EVs. Atomic force microscope imaging combined with machine-learning methods further emphasizes the difference in biophysical properties between the two subpopulations. These results shed light on the sophisticated mechanism by which malaria parasites utilize EV subpopulations as a communication tool to target different cellular destinations or host systems.
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Affiliation(s)
- Paula Abou Karam
- Department of Biomolecular SciencesWeizmann Institute of ScienceRehovotIsrael
| | | | - Tamar Ziv
- Smoler Proteomics CenterDepartment of BiologyTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Hila Ben Ami Pilo
- Department of Biomolecular SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Ido Azuri
- Bioinformatics UnitLife Sciences Core FacilitiesWeizmann Institute of ScienceRehovotIsrael
| | - Anna Rivkin
- Department of Biomolecular SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Edo Kiper
- Department of Biomolecular SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Ron Rotkopf
- Bioinformatics UnitLife Sciences Core FacilitiesWeizmann Institute of ScienceRehovotIsrael
| | - Sidney R Cohen
- Department of Chemical Research SupportWeizmann Institute of ScienceRehovotIsrael
| | | | - Ori Avinoam
- Department of Biomolecular SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Alicia Rojas
- Laboratory of HelminthologyFaculty of MicrobiologyUniversity of Costa RicaSan JoséCosta Rica
| | - Mattia I Morandi
- Department of Biomolecular SciencesWeizmann Institute of ScienceRehovotIsrael
| | - Neta Regev‐Rudzki
- Department of Biomolecular SciencesWeizmann Institute of ScienceRehovotIsrael
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3
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Insights into molecular mechanism of action of citrus flavonoids hesperidin and naringin on lipid bilayers using spectroscopic, calorimetric, microscopic and theoretical studies. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118411] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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4
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Recent progress of vibrational spectroscopic study on the interfacial structure of biomimetic membranes. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2021. [DOI: 10.1016/j.cjac.2021.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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5
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Redondo-Morata L, Losada-Pérez P, Giannotti MI. Lipid bilayers: Phase behavior and nanomechanics. CURRENT TOPICS IN MEMBRANES 2020; 86:1-55. [PMID: 33837691 DOI: 10.1016/bs.ctm.2020.08.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lipid membranes are involved in many physiological processes like recognition, signaling, fusion or remodeling of the cell membrane or some of its internal compartments. Within the cell, they are the ultimate barrier, while maintaining the fluidity or flexibility required for a myriad of processes, including membrane protein assembly. The physical properties of in vitro model membranes as model cell membranes have been extensively studied with a variety of techniques, from classical thermodynamics to advanced modern microscopies. Here we review the nanomechanics of solid-supported lipid membranes with a focus in their phase behavior. Relevant information obtained by quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM) as complementary techniques in the nano/mesoscale interface is presented. Membrane morphological and mechanical characterization will be discussed in the framework of its phase behavior, phase transitions and coexistence, in simple and complex models, and upon the presence of cholesterol.
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Affiliation(s)
- Lorena Redondo-Morata
- Center for Infection and Immunity of Lille, INSERM U1019, CNRS UMR 8204, Lille, France
| | - Patricia Losada-Pérez
- Experimental Soft Matter and Thermal Physics (EST) Group, Department of Physics, Université Libre de Bruxelles, Brussels, Belgium
| | - Marina Inés Giannotti
- Biomedical Research Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, Spain; Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain; Departament de Ciència de Materials i Química Física, Universitat de Barcelona, Barcelona, Spain.
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6
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l-Ascorbic acid alkyl esters action on stratum corneum model membranes: An insight into the mechanism for enhanced skin permeation. Colloids Surf B Biointerfaces 2020; 185:110621. [PMID: 31726308 DOI: 10.1016/j.colsurfb.2019.110621] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 10/17/2019] [Accepted: 10/28/2019] [Indexed: 12/26/2022]
Abstract
L-ascorbic acid alkyl esters (ASCn) are lipophilic forms of vitamin C, which act as skin permeation enhancers. We investigated the physical changes induced by incorporating ASCn into stratum corneum (SC) lipid membranes and correlated this with the mechanism proposed in the literature for skin permeation enhancement phenomena. We used lipid monolayers to explore the 2D structure and elasticity of the lipid-enhancer systems. As a comparison, the classic permeation enhancer, oleic acid (OA) and the non-enhancer analogue stearic acid (SA) were analysed. The incorporation of ASCn or OA into SC membranes resulted in more liquid-like films, with a dose-dependent lowering of the compressibility modulus. Brewster angle microscopy (BAM) evidenced partial miscibility of the enhancer with SC lipid components, stabilising the liquid-expanded phase. At the nanoscale, AFM showed that SC lipids form heterogeneous membranes, which underwent structural alterations after incorporating ASCn and fatty acids, such as SA and OA. The lower, cholesterol-enriched phase appears to concentrate the enhancers, whilst the higher ceramide-enriched phase concentrated the non-enhancer SA. Our results and previously reported pieces of evidence indicate a strong pattern in which the rheological properties of SC lipid films are determinant for skin permeation phenomena.
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Characterization and lipid phase effect on the interaction of GBV-C E2-derived peptide, P6-2VIR576, with lipid membranes relating it with the HIV-1 FP inhibition. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.06.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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8
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Hu Q, Weber C, Cheng HW, Renner FU, Valtiner M. Anion Layering and Steric Hydration Repulsion on Positively Charged Surfaces in Aqueous Electrolytes. Chemphyschem 2017; 18:3056-3065. [PMID: 28872763 DOI: 10.1002/cphc.201700865] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 08/29/2017] [Indexed: 11/10/2022]
Abstract
The molecular structure at charged solid/liquid interfaces is vital for many chemical or electrochemical processes, such as adhesion, catalysis, or the stability of colloidal dispersions. How cations influence structural hydration forces and interactions across negatively charged surfaces has been studied in great detail. However, how anions influence structural hydration forces on positively charged surfaces is much less understood. Herein we report force versus distance profiles on freshly cleaved mica using atomic force microscopy with silicon tips. We characterize steric anion hydration forces for a set of common anions (Cl- , ClO4- , NO3- , SO42- and PO43- ) in pure acids at pH ≈1, where protons are the co-ions. Solutions containing anions with low hydration energies exhibit repulsive structural hydration forces, indicating significant ion and/or water structuring within the first 1-2 nm on a positively charged surface. We attribute this to specific adsorption effects within the Stern layer. In contrast, ions with high hydration energies show exponentially repulsive hydration forces, indicating a lower degree of structuring within the Stern layer. The presented data demonstrates that anion hydration forces in the inner double layer are comparable to cation hydration forces, and that they qualitatively correlate with hydration free energies. This work contributes to understanding interaction processes in which positive charge is screened by anions within an electrolyte.
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Affiliation(s)
- Qingyun Hu
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH, D-40237, Düsseldorf, Germany
| | - Christian Weber
- Institut für Physikalische Chemie der TU Bergakademie Freiberg, 09599, Freiberg, Germany
| | - Hsiu-Wei Cheng
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH, D-40237, Düsseldorf, Germany.,Institut für Physikalische Chemie der TU Bergakademie Freiberg, 09599, Freiberg, Germany
| | - Frank Uwe Renner
- Institute of Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590, Diepenbeek, Belgium
| | - Markus Valtiner
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH, D-40237, Düsseldorf, Germany.,Institut für Physikalische Chemie der TU Bergakademie Freiberg, 09599, Freiberg, Germany
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9
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Ruiz-Rincón S, González-Orive A, de la Fuente JM, Cea P. Reversible Monolayer-Bilayer Transition in Supported Phospholipid LB Films under the Presence of Water: Morphological and Nanomechanical Behavior. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:7538-7547. [PMID: 28691823 DOI: 10.1021/acs.langmuir.7b01268] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Mixed monolayer Langmuir-Blodgett (LB) films of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cholesterol (Chol) in the 1:1 ratio have been prepared onto solid mica substrates. Upon immersion in water or in an aqueous HEPES solution (pH 7.4) the monolayer LB films were spontaneously converted into well-organized bilayers leaving free mica areas. The process has been demonstrated to be reversible upon removal of the aqueous solution, resulting in remarkably free of defects monolayers that are homogeneously distributed onto the mica. In addition, the nanomechanical properties exhibited by the as-formed bilayers have been determined by means of AFM breakthrough force studies. The bilayers formed by immersion of the monolayer in an aqueous media exhibit nanomechanical properties and stability under compression analogous to those of DPPC:Chol supported bilayers obtained by other methods previously described in the literature. Consequently, the hydration of a monolayer LB film has been revealed as an easy method to produce well-ordered bilayers that mimic the cell membrane and that could be used as model cell membranes.
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Affiliation(s)
| | | | - Jesús M de la Fuente
- Instituto de Ciencia de Materiales de Aragón (ICMA), Universidad de Zaragoza-CSIC , 50009 Zaragoza, Spain
- Networking Biomedical Research Center of Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN), Zaragoza, Spain
| | - Pilar Cea
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza , 50009, Zaragoza, Spain
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10
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Hoyo J, Guaus E, Torrent-Burgués J. Tuning ubiquinone position in biomimetic monolayer membranes. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2017; 40:62. [PMID: 28620696 DOI: 10.1140/epje/i2017-11552-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 05/29/2017] [Indexed: 06/07/2023]
Abstract
Artificial lipid bilayers have been extensively studied as models that mimic natural membranes (biomimetic membranes). Several attempts of biomimetic membranes inserting ubiquinone (UQ) have been performed to enlighten which the position of UQ in the lipid layer is, although obtaining contradictory results. In this work, pure components (DPPC and UQ) and DPPC:UQ mixtures have been studied using surface pressure-area isotherms and Langmuir-Blodgett (LB) films of the same compounds have been transferred onto solid substrates being topographically characterized on mica using atomic force microscopy and electrochemically on indium tin oxide slides. DPPC:UQ mixtures present less solid-like physical state than pure DPPC indicating a higher-order degree for the latter. UQ influences considerably DPPC during the fluid state, but it is mainly expelled after the phase transition at [Formula: see text] 26 mN·m^-1 for the 5:1 ratio and at [Formula: see text] 21 mN·m^-1 for lower UQ content. The thermodynamic studies confirm the stability of the DPPC:UQ mixtures before that event, although presenting a non-ideal behaviour. The results indicate that UQ position can be tuned by means of the surface pressure applied to obtain LB films and the UQ initial content. The UQ positions in the biomimetic membrane are distinguished by their formal potential: UQ located in "diving" position with the UQ placed in the DPPC matrix in direct contact with the electrode surface ( -0.04±0.02 V), inserted between lipid chains without contact to the substrate ( 0.00±0.01 V) and parallel to the substrate, above the lipid chains ( 0.09±0.02 V).
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Affiliation(s)
- Javier Hoyo
- Universitat Politècnica de Catalunya, Dpt. Chemical Engineering, 08222, Terrassa, Barcelona, Spain.
| | - Ester Guaus
- Universitat Politècnica de Catalunya, Dpt. Chemical Engineering, 08222, Terrassa, Barcelona, Spain
| | - Juan Torrent-Burgués
- Universitat Politècnica de Catalunya, Dpt. Chemical Engineering, 08222, Terrassa, Barcelona, Spain
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11
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Micklavzina BL, Zhang S, He H, Longo ML. Nanomechanical Characterization of Micellar Surfactant Films via Atomic Force Microscopy at a Graphite Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2122-2132. [PMID: 28170269 DOI: 10.1021/acs.langmuir.6b04315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this work, we study the mechanical properties of sodium dodecyl sulfate (SDS) and dodecylamine hydrochloride (DAH) micellar films at a graphite surface via atomic force microscopy (AFM). Breakthrough forces for these films were measured using silicon nitride cantilevers and were found to be 1.1 ± 0.1 nN for a 10 mM DAH film and 3.0 ± 0.3 nN for a 10 mM SDS film. For 10 mM SDS films, it was found that the addition of 1.5 mM of NaCl, Na2SO4, or MgCl2 produced a 50-70% increase in the measured breakthrough force. Similar results were found for 10 mM DAH films when NaCl and MgCl2 were added. A model was developed on the basis of previous work on lipid films and CMC data gathered via spectrofluorometry measurements to predict the change in normalized breakthrough forces with added salt concentrations for SDS and DAH films. Using this model, it was found that the activation volume required to initiate the breakthrough was roughly 0.4 nm3 for SDS and 0.3 nm3 for DAH, roughly the volume of a single molecule. Normalized breakthrough force data for SDS films with added MgCl2 showed an unexpected dip at low added salt concentrations. The model was adapted to account for changing activation volumes, and a curve of activation volume versus magnesium concentration was obtained, showing a minimum volume of 0.21 nm3. The addition of 0.2 mM SDS to a 10 mM DAH solution was found to double the measured breakthrough force of the film. Images taken of the surface showed a phase change from cylindrical hemimicelles to a planar film that may have produced the observed differences. The pH of the bulk solution was varied for both 10 mM SDS and DAH films and was found to have little effect on the breakthrough force.
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Affiliation(s)
- Benjamin L Micklavzina
- Department of Materials Science and Engineering and ‡Department of Chemical Engineering, University of California , Davis, California 95616, United States
- Department of Polymer Science and Engineering and ∥Department of Materials Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Shengwei Zhang
- Department of Materials Science and Engineering and ‡Department of Chemical Engineering, University of California , Davis, California 95616, United States
- Department of Polymer Science and Engineering and ∥Department of Materials Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Hao He
- Department of Materials Science and Engineering and ‡Department of Chemical Engineering, University of California , Davis, California 95616, United States
- Department of Polymer Science and Engineering and ∥Department of Materials Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Marjorie L Longo
- Department of Materials Science and Engineering and ‡Department of Chemical Engineering, University of California , Davis, California 95616, United States
- Department of Polymer Science and Engineering and ∥Department of Materials Science and Engineering, Zhejiang University , Hangzhou 310027, China
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12
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Gräb O, Abacilar M, Daus F, Geyer A, Steinem C. 3D-Membrane Stacks on Supported Membranes Composed of Diatom Lipids Induced by Long-Chain Polyamines. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10144-10152. [PMID: 27603681 DOI: 10.1021/acs.langmuir.6b02575] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Long-chain polyamines (LCPAs) are intimately involved in the biomineralization process of diatoms taking place in silica deposition vesicles being acidic compartments surrounded by a lipid bilayer. Here, we addressed the question whether and how LCPAs interact with lipid membranes composed of glycerophospholipids and glyceroglycolipids mimicking the membranes of diatoms and higher plants. Solid supported lipid bilayers and monolayers containing the three major components that are unique in diatoms and higher plants, i.e., monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), and sulfoquinovosyldiacylglycerol (SQDG), were prepared by spreading small unilamellar vesicles. The integrity of the membranes was investigated by fluorescence microscopy and atomic force microscopy showing continuous flat bilayers and monolayers with small protrusions on top of the membrane. The addition of a synthetic polyamine composed of 13 amine groups separated by a propyl spacer (C3N13) results in flat but three-dimensional membrane stacks within minutes. The membrane stacks are connected with the underlying membrane as verified by fluorescence recovery after photobleaching experiments. Membrane stack formation was found to be independent of the lipid composition; i.e., neither glyceroglycolipids nor negatively charged lipids were required. However, the formation process was strongly dependent on the chain length of the polyamine. Whereas short polyamines such as the naturally occurring spermidine, spermine, and the synthetic polyamines C3N4 and C3N5 do not induce stack formation, those containing seven and more amine groups (C3N7, C3N13, and C3N18) do form membrane stacks. The observed stack formation might have implications for the stability and expansion of the silica deposition vesicle during valve and girdle band formation in diatoms.
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Affiliation(s)
- Oliver Gräb
- Institute of Organic and Biomolecular Chemistry, University of Göttingen , Tammannstr. 2, 37077 Göttingen, Germany
| | - Maryna Abacilar
- Faculty of Chemistry, Philipps-University Marburg , Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Fabian Daus
- Faculty of Chemistry, Philipps-University Marburg , Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Armin Geyer
- Faculty of Chemistry, Philipps-University Marburg , Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Claudia Steinem
- Institute of Organic and Biomolecular Chemistry, University of Göttingen , Tammannstr. 2, 37077 Göttingen, Germany
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Tabaei SR, Vafaei S, Cho NJ. Fabrication of charged membranes by the solvent-assisted lipid bilayer (SALB) formation method on SiO2 and Al2O3. Phys Chem Chem Phys 2016; 17:11546-52. [PMID: 25858554 DOI: 10.1039/c5cp01428j] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this study, we employed the solvent-assisted lipid bilayer (SALB) formation method to fabricate charged membranes on solid supports. The SALB formation method exploits a ternary mixture of lipid-alcohol-aqueous buffer to deposit lamellar phase structures on solid supports upon gradual increase of the buffer fraction. Using the quartz crystal microbalance with dissipation (QCM-D) technique, we investigated the formation of negatively and positively charged membranes via the SALB formation method and directly compared with the vesicle fusion method on two different oxide films. Bilayers containing an increasing fraction of negatively charged DOPS lipid molecules were successfully formed on both SiO2 and Al2O3 substrates using the SALB formation method at physiological pH (7.5). In contrast, the vesicle fusion method did not support bilayer formation on Al2O3 and those containing more than 10% DOPS ruptured on SiO2 only under acidic conditions (pH 5). Characterization of the fraction of negatively charge DOPS by in situ annexin 5A binding assay revealed that the fraction of DOPS lipid molecules in the bilayers formed on Al2O3 is significantly higher than that formed on SiO2. This suggests that the SALB self-assembly of charged membranes is predominantly governed by the electrostatic interaction. Furthermore, our findings indicate that when multicomponent lipid mixtures are used, the relative fraction of lipids in the bilayer may differ from the fraction of lipids in the precursor mixture.
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Affiliation(s)
- Seyed R Tabaei
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore.
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14
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Gillissen JJJ, Tabaei SR, Cho NJ. A phenomenological model of the solvent-assisted lipid bilayer formation method. Phys Chem Chem Phys 2016; 18:24157-63. [DOI: 10.1039/c6cp04816a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The mechanism of solvent-assisted lipid bilayer assembly at the solid–liquid interface is elucidated by matching an adsorption model to quartz crystal microbalance data.
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Affiliation(s)
- Jurriaan J. J. Gillissen
- School of Materials Science and Engineering
- Nanyang Technological University
- Singapore
- Centre for Biomimetic Sensor Science
- Nanyang Technological University
| | - Seyed R. Tabaei
- School of Materials Science and Engineering
- Nanyang Technological University
- Singapore
- Centre for Biomimetic Sensor Science
- Nanyang Technological University
| | - Nam-Joon Cho
- School of Materials Science and Engineering
- Nanyang Technological University
- Singapore
- Centre for Biomimetic Sensor Science
- Nanyang Technological University
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15
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Tabaei SR, Jackman JA, Kim M, Yorulmaz S, Vafaei S, Cho NJ. Biomembrane Fabrication by the Solvent-assisted Lipid Bilayer (SALB) Method. J Vis Exp 2015. [PMID: 26650537 PMCID: PMC4692765 DOI: 10.3791/53073] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In order to mimic cell membranes, the supported lipid bilayer (SLB) is an attractive platform which enables in vitro investigation of membrane-related processes while conferring biocompatibility and biofunctionality to solid substrates. The spontaneous adsorption and rupture of phospholipid vesicles is the most commonly used method to form SLBs. However, under physiological conditions, vesicle fusion (VF) is limited to only a subset of lipid compositions and solid supports. Here, we describe a one-step general procedure called the solvent-assisted lipid bilayer (SALB) formation method in order to form SLBs which does not require vesicles. The SALB method involves the deposition of lipid molecules onto a solid surface in the presence of water-miscible organic solvents (e.g., isopropanol) and subsequent solvent-exchange with aqueous buffer solution in order to trigger SLB formation. The continuous solvent exchange step enables application of the method in a flow-through configuration suitable for monitoring bilayer formation and subsequent alterations using a wide range of surface-sensitive biosensors. The SALB method can be used to fabricate SLBs on a wide range of hydrophilic solid surfaces, including those which are intractable to vesicle fusion. In addition, it enables fabrication of SLBs composed of lipid compositions which cannot be prepared using the vesicle fusion method. Herein, we compare results obtained with the SALB and conventional vesicle fusion methods on two illustrative hydrophilic surfaces, silicon dioxide and gold. To optimize the experimental conditions for preparation of high quality bilayers prepared via the SALB method, the effect of various parameters, including the type of organic solvent in the deposition step, the rate of solvent exchange, and the lipid concentration is discussed along with troubleshooting tips. Formation of supported membranes containing high fractions of cholesterol is also demonstrated with the SALB method, highlighting the technical capabilities of the SALB technique for a wide range of membrane configurations.
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Affiliation(s)
- Seyed R Tabaei
- School of Materials Science and Engineering, Nanyang Technological University; Centre for Biomimetic Sensor Science, Nanyang Technological University
| | - Joshua A Jackman
- School of Materials Science and Engineering, Nanyang Technological University; Centre for Biomimetic Sensor Science, Nanyang Technological University
| | - Minchul Kim
- School of Materials Science and Engineering, Nanyang Technological University; Centre for Biomimetic Sensor Science, Nanyang Technological University
| | - Saziye Yorulmaz
- School of Materials Science and Engineering, Nanyang Technological University; Centre for Biomimetic Sensor Science, Nanyang Technological University
| | - Setareh Vafaei
- School of Materials Science and Engineering, Nanyang Technological University; Centre for Biomimetic Sensor Science, Nanyang Technological University
| | - Nam-Joon Cho
- School of Materials Science and Engineering, Nanyang Technological University; Centre for Biomimetic Sensor Science, Nanyang Technological University; School of Chemical and Biomedical Engineering, Nanyang Technological University;
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16
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Angle MR, Wang A, Thomas A, Schaefer AT, Melosh NA. Penetration of cell membranes and synthetic lipid bilayers by nanoprobes. Biophys J 2015; 107:2091-100. [PMID: 25418094 DOI: 10.1016/j.bpj.2014.09.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/08/2014] [Accepted: 09/16/2014] [Indexed: 11/28/2022] Open
Abstract
Nanoscale devices have been proposed as tools for measuring and controlling intracellular activity by providing electrical and/or chemical access to the cytosol. Unfortunately, nanostructures with diameters of 50-500 nm do not readily penetrate the cell membrane, and rationally optimizing nanoprobes for cell penetration requires real-time characterization methods that are capable of following the process of membrane penetration with nanometer resolution. Although extensive work has examined the rupture of supported synthetic lipid bilayers, little is known about the applicability of these model systems to living cell membranes with complex lipid compositions, cytoskeletal attachment, and membrane proteins. Here, we describe atomic force microscopy (AFM) membrane penetration experiments in two parallel systems: live HEK293 cells and stacks of synthetic lipid bilayers. By using the same probes in both systems, we were able to clearly identify membrane penetration in synthetic bilayers and compare these events with putative membrane penetration events in cells. We examined membrane penetration forces for three tip geometries and 18 chemical modifications of the probe surface, and in all cases the median forces required to penetrate cellular and synthetic lipid bilayers with nanoprobes were greater than 1 nN. The penetration force was sensitive to the probe's sharpness, but not its surface chemistry, and the force did not depend on cell surface or cytoskeletal properties, with cells and lipid stacks yielding similar forces. This systematic assessment of penetration under various mechanical and chemical conditions provides insights into nanoprobe-cell interactions and informs the design of future intracellular nanoprobes.
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Affiliation(s)
- Matthew R Angle
- Department of Materials Science and Engineering, Stanford University, Stanford, California
| | - Andrew Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, California
| | - Aman Thomas
- Department of Materials Science and Engineering, Stanford University, Stanford, California
| | - Andreas T Schaefer
- Department of Materials Science and Engineering, Stanford University, Stanford, California
| | - Nicholas A Melosh
- Department of Materials Science and Engineering, Stanford University, Stanford, California.
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17
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Barrán-Berdón AL, Yélamos B, García-Río L, Domènech Ò, Aicart E, Junquera E. Polycationic Macrocyclic Scaffolds as Potential Non-Viral Vectors of DNA: A Multidisciplinary Study. ACS APPLIED MATERIALS & INTERFACES 2015; 7:14404-14414. [PMID: 26067709 DOI: 10.1021/acsami.5b03231] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The potential of lipoplexes constituted by the DNA pEGFP-C3 (encoding green fluorescent protein), polycationic calixarene-based macrocyclic vector (CxCL) with a lipidic matrix (herein named TMAC4), and zwitterionic lipid 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) as nontoxic DNA vectors has been analyzed from both biophysical and biochemical perspectives. For that purpose, several experimental methods, such as zeta potential (PALS methodology), agarose gel electrophoresis, small-angle X-ray scattering (SAXS), transmission electronic cryo-microscopy (cryo-TEM), atomic force microscopy (AFM), fluorescence microscopy, and cytotoxicity assays have been used. The electrochemical study shows that TMAC4 has 100% of its nominal charge available, whereas pDNA presents an effective negative charge that is only 10% that of its nominal one. PALS studies indicate the presence of three populations of nanoaggregates in TMAC4/DOPE lipid mixtures, with sizes of approximately 100, 17, and 6 nm, compatible with liposomes, oblate micelles, and spherical micelles, respectively, the first two also being detected by cryo-TEM. However, in the presence of pDNA, this mixture is organized in Lα multilamellar structures at all compositions. In fact, cryo-TEM micrographs show two types of multilamellar aggregation patterns: cluster-type at low and moderate CxCL molar fractions in the TMAC4/DOPE lipid mixture (α = 0.2 and 0.5), and fingerprint-type (FP), which are only present at low CxCL molar fraction (α = 0.2). This structural scenario has also been observed in SAXS diffractograms, including the coexistence of two different phases when DOPE dominates in the mixture. AFM experiments at α = 0.2 provide evidence that pDNA makes the lipid bilayer more deformable, thus promoting a potential enhancement in the capability of penetrating the cells. In fact, the best transfection perfomances of these TMAC4/DOPE-pDNA lipoplexes have been obtained at low CxCL molar fractions (α = 0.2) and a moderate-to-high effective charge ratio (ρeff = 20). Presumably, the coexistence of two lamellar phases is responsible for the better TE performance at low α.
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Affiliation(s)
| | | | - Luis García-Río
- ⊥Departamento de Química Física, Centro de Investigación en Química Biológica y Materiales Moleculares, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Òscar Domènech
- §Departamento de Fisicoquímica, Facultat de Farmàcia, Universitat de Barcelona, 08028 Barcelona, Spain
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18
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Li Y, Zhu C, Zhu J, Liang H, Chen D, Zhao H, Liu B. Nanomechanics of phospholipid LB film studied layer by layer with AFM. Chem Cent J 2014; 8:71. [PMID: 25614761 PMCID: PMC4279057 DOI: 10.1186/s13065-014-0071-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 11/11/2014] [Indexed: 11/21/2022] Open
Abstract
Background Phospholipid, a main component of cell membrane, has been explored as a model system of the cell membrane and temporary scaffold materials in recent studies. The mechanical properties of phospholipid layers are essentially interesting since it is involved in several biological processes. Results Here, the nanomechanical properties such as indentation force, adhesion force and DMT (Derjaguin-Müller-Toporov) modulus of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) Langmuir-Blodgett (LB) films were analyzed layer by layer with Atomic Force Microscope (AFM) under deionized water condition. Conclusions The penetration distances in the indentation force curves are equal to the thicknesses of phospholipid films, and the yield forces of DSPC LB films in deionized water are smaller than that of similar lipid films in buffered solutions due to the influence of ions. Moreover, the DMT modulus of upper layer DSPC LB film is different from that of monolayer DSPC LB film due to the influence of their different substrates. Our results suggest that environment such as surrounding ions and substrate will strongly influence the measured nano-mechanical properties of the lipid bilayer, especially that of the down layer. A process about the exploration of nanomechanics of DSPC LB film. ![]()
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Affiliation(s)
- Yinli Li
- Institute of Photo-biophysics, School of Physics and Electronic, Henan University, Kaifeng, 475004 Henan PR China
| | - Changjiang Zhu
- College of Software, Henan University, Kaifeng, 475004 Henan PR China
| | - Jichun Zhu
- Institute of Photo-biophysics, School of Physics and Electronic, Henan University, Kaifeng, 475004 Henan PR China
| | - Hao Liang
- Institute of Photo-biophysics, School of Physics and Electronic, Henan University, Kaifeng, 475004 Henan PR China
| | - Dong Chen
- Institute of Photo-biophysics, School of Physics and Electronic, Henan University, Kaifeng, 475004 Henan PR China
| | - Huiling Zhao
- Institute of Photo-biophysics, School of Physics and Electronic, Henan University, Kaifeng, 475004 Henan PR China
| | - Bo Liu
- Institute of Photo-biophysics, School of Physics and Electronic, Henan University, Kaifeng, 475004 Henan PR China
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19
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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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20
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Sorkin R, Dror Y, Kampf N, Klein J. Mechanical stability and lubrication by phosphatidylcholine boundary layers in the vesicular and in the extended lamellar phases. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:5005-5014. [PMID: 24708462 DOI: 10.1021/la500420u] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The lubrication properties of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) extended supported bilayers were studied and compared to those of surface-attached DSPC small unilamellar vesicles (liposomes) in order to elucidate the effect of phospholipid geometrical packaging on the lubrication and mechanical properties of these boundary layers. The topography and response to the nanoindentation of bilayer- and liposome-covered surfaces were studied by an atomic force microscope (AFM). In parallel, normal and shear (frictional) forces between two opposing surfaces bearing DSPC vesicles/bilayers across water were studied with the surface force balance (SFB). A correlation between nanomechanical performance in the AFM and stability and lubrication in the SFB was observed. Bilayers were readily punctured by the AFM tip and exhibited substantial hysteresis between approach and retraction curves, whereas liposomes were not punctured and exhibited purely elastic behavior. At the same time, SFB measurements showed that bilayers are less stable and less efficient lubricants compared to liposomes. Bilayers provided efficient lubrication with very low friction coefficients, 0.002-0.008 up to pressures of more then 50 atm. However, bilayers were less robust and tended to detach from the surface as a result of shear, leading to high friction for subsequent approaches at the same contact position. In contrast, liposomes showed reversible and reproducible behavior under shear and compression, exhibiting ultralow friction coefficients of μ ≈ 10(-4) for pressures as high as 180 atm. This is attributed to the increased mechanical stability of the self-closed, closely packed liposomes, which we believe results from the more defect-free nature of the finitely sized vesicles.
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Affiliation(s)
- Raya Sorkin
- Department of Materials and Interfaces, Weizmann Institute of Science , Rehovot 76100, Israel
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21
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Costa L, Rodrigues MS, Newman E, Zubieta C, Chevrier J, Comin F. Imaging material properties of biological samples with a force feedback microscope. J Mol Recognit 2013; 26:689-93. [DOI: 10.1002/jmr.2328] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 09/06/2013] [Accepted: 09/12/2013] [Indexed: 10/26/2022]
Affiliation(s)
- Luca Costa
- European Synchrotron Radiation Facility; 6 rue Jules Horowitz BP 220 38043 Grenoble, CEDEX France
- Université Joseph Fourier BP 53; 38041 Grenoble, CEDEX 9 France
| | - Mario S Rodrigues
- CFMC/Dep. Fisica, Faculdade de Ciências; Universidade de Lisboa; Campo Grande 1749-016 Lisboa Portugal
| | - Emily Newman
- European Molecular Biology Laboratory; 6 rue Jules Horowitz BP 181 38041 Grenoble, CEDEX 9 France
| | - Chloe Zubieta
- European Synchrotron Radiation Facility; 6 rue Jules Horowitz BP 220 38043 Grenoble, CEDEX France
| | - Joёl Chevrier
- European Synchrotron Radiation Facility; 6 rue Jules Horowitz BP 220 38043 Grenoble, CEDEX France
- Université Joseph Fourier BP 53; 38041 Grenoble, CEDEX 9 France
- Institut Néel CNRS BP 166; 38042 Grenoble, CEDEX 9 France
| | - Fabio Comin
- European Synchrotron Radiation Facility; 6 rue Jules Horowitz BP 220 38043 Grenoble, CEDEX France
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22
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Picas L, Milhiet PE, Hernández-Borrell J. Atomic force microscopy: a versatile tool to probe the physical and chemical properties of supported membranes at the nanoscale. Chem Phys Lipids 2012. [PMID: 23194897 DOI: 10.1016/j.chemphyslip.2012.10.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Atomic force microscopy (AFM) was developed in the 1980s following the invention of its precursor, scanning tunneling microscopy (STM), earlier in the decade. Several modes of operation have evolved, demonstrating the extreme versatility of this method for measuring the physicochemical properties of samples at the nanoscopic scale. AFM has proved an invaluable technique for visualizing the topographic characteristics of phospholipid monolayers and bilayers, such as roughness, height or laterally segregated domains. Implemented modes such as phase imaging have also provided criteria for discriminating the viscoelastic properties of different supported lipid bilayer (SLB) regions. In this review, we focus on the AFM force spectroscopy (FS) mode, which enables determination of the nanomechanical properties of membrane models. The interpretation of force curves is presented, together with newly emerging techniques that provide complementary information on physicochemical properties that may contribute to our understanding of the structure and function of biomembranes. Since AFM is an imaging technique, some basic indications on how real-time AFM imaging is evolving are also presented at the end of this paper.
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Affiliation(s)
- Laura Picas
- Institut Curie, CNRS UMR 144, 26 rue d'Ulm, 75248 Paris, France
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23
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Shi Y, Lu Q. Fast amplitude modulation detector for scanning force microscopy with high Q factor. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2012; 18:1016-1020. [PMID: 23026313 DOI: 10.1017/s1431927612001146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Amplitude modulation (AM) scanning force microscopy (SFM) is superior to frequency modulation SFM in simplicity, sensitivity, and stability, but is still replaced by the latter because it is too slow when the Q factor is high (bandwidth < 0.5 Hz for Q > 50,000 and resonant frequency ω0 < 50 kHz). We report a close-loop AM detector that has an 18 Hz bandwidth, better than 1 mHz frequency resolution and excellent response to step frequency changes even for Q ∼ 60,000 and ω0 ∼ 32 kHz. Its superiority is well shown by the comparison of magnetic force microscope images taken under the new and old AM detection modes with the tip and scan area (videotape sample) being unchanged. Also important is that shifting the driving frequency from near the resonance peak to further away from the peak does not decrease the frequency resolution as much as we expect (but can increase the response speed).
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Affiliation(s)
- Yizhi Shi
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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24
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El Zein R, Dallaporta H, Charrier AM. Supported Lipid Monolayer with Improved Nanomechanical Stability: Effect of Polymerization. J Phys Chem B 2012; 116:7190-5. [DOI: 10.1021/jp302306r] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Racha El Zein
- CNRS, UMR7325, 13288, Marseille,
France, and Aix-Marseille University, CINaM,
13288, Marseille, France
| | - Hervé Dallaporta
- CNRS, UMR7325, 13288, Marseille,
France, and Aix-Marseille University, CINaM,
13288, Marseille, France
| | - Anne M. Charrier
- CNRS, UMR7325, 13288, Marseille,
France, and Aix-Marseille University, CINaM,
13288, Marseille, France
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25
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Balasuriya TS, Ong L, Gras SL, Dagastine RR. Changes in morphological and nano-mechanical properties of the milk fat globule membrane during processing. RSC Adv 2012. [DOI: 10.1039/c2ra00844k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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26
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Goldberg R, Klein J. Liposomes as lubricants: beyond drug delivery. Chem Phys Lipids 2011; 165:374-81. [PMID: 22119851 DOI: 10.1016/j.chemphyslip.2011.11.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 11/10/2011] [Accepted: 11/11/2011] [Indexed: 10/15/2022]
Abstract
In this paper we review recent work (Goldberg et al., 2011a,b) on a new use for phosphatidylcholine liposomes: as ultra-efficient boundary lubricants at up to the highest physiological pressures. Using a surface force balance, we have measured the normal and shear interactions as a function of surface separation between layers of hydrogenated soy phophatidylcholine (HSPC) small unilamellar vesicles (SUVs) adsorbed from dispersion, at both pure water and physiologically high salt concentrations of 0.15 M NaNO(3). Cryo-Scanning Electron Microscopy shows each surface to be coated by a close-packed HSPC-SUV layer with an over-layer of liposomes on top. The shear forces reveal strikingly low friction coefficients down to 2×10(-5) in pure water system or 6×10(-4) in the 150 mM salt system, up to contact pressures of at least 12 MPa (pure water) or 6 MPa (high salt), comparable with those in the major joints. This low friction is attributed to the hydration lubrication mechanism arising from rubbing of the highly hydrated phosphocholine-headgroup layers exposed at the outer surface of each liposome, and provides support for the conjecture that phospholipids may play a significant role in biological lubrication.
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Affiliation(s)
- Ronit Goldberg
- Dept. of Materials and Interfaces, Weizmann Institute, Rehovot 76100, Israel
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27
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Goldberg R, Schroeder A, Barenholz Y, Klein J. Interactions between adsorbed hydrogenated soy phosphatidylcholine (HSPC) vesicles at physiologically high pressures and salt concentrations. Biophys J 2011; 100:2403-11. [PMID: 21575574 DOI: 10.1016/j.bpj.2011.03.061] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 03/20/2011] [Accepted: 03/25/2011] [Indexed: 10/18/2022] Open
Abstract
Using a surface force balance, we measured normal and shear interactions as a function of surface separation between layers of hydrogenated soy phosphatidylcholine (HSPC) small unilamellar vesicles (SUVs) adsorbed from dispersion at physiologically high salt concentrations (0.15 M NaNO₃). Cryo-scanning electron microscopy shows that each surface is coated by a close-packed HSPC-SUV layer with an overlayer of liposomes on top. A clear attractive interaction between the liposome layers is seen upon approach and separation, followed by a steric repulsion upon further compression. The shear forces reveal low friction coefficients (μ = 0.008-0.0006) up to contact pressures of at least 6 MPa, comparable to those observed in the major joints. The spread in μ-values may be qualitatively accounted for by different local liposome structure at different contact points, suggesting that the intrinsic friction of the HSPC-SUV layers at this salt concentration is closer to the lower limit (μ = ~0.0006). This low friction is attributed to the hydration lubrication mechanism arising from rubbing of the hydrated phosphocholine-headgroup layers exposed at the outer surface of each liposome, and provides support for the conjecture that phospholipids may play a significant role in biological lubrication.
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Affiliation(s)
- Ronit Goldberg
- Department of Materials and Interfaces, Weizmann Institute, Rehovot, Israel
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28
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Gallier S, Gragson D, Jiménez-Flores R, Everett DW. Surface characterization of bovine milk phospholipid monolayers by Langmuir isotherms and microscopic techniques. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:12275-12285. [PMID: 21067228 PMCID: PMC4392927 DOI: 10.1021/jf102185a] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Monolayers were prepared from phospholipids extracted from bovine milk and used as a model system to mimic the native milk fat globule membrane (MFGM) surface structure in various microscopic experiments. The natural complex mixtures of phospholipids were isolated from bovine raw milk, raw cream, processed whole milk, and buttermilk powder by total lipid extraction and solid-phase extraction. A Langmuir film balance mounted on an epifluorescence microscope was used to analyze the physical behavior of the monolayer films and the phase coexistence resulting from the formation of phospholipid microdomains within these films. Atomic force microscopy was used for nanometer-scale topographic resolution of the microdomains. This study allowed comparison of the behavior of phospholipid monolayers from dairy products at different stages of processing, analysis of the formation of microdomains, and the study of the effect of milk processing on lipid-lipid interactions and phase coexistence. It was observed that milk processing changes the physical behavior of phospholipid monolayers by altering the phospholipid profile and the fatty acid distribution.
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Affiliation(s)
- Sophie Gallier
- Department of Food Science, University of Otago, Dunedin, New Zealand
- Dairy Products Technology Center, California Polytechnic State University, San Luis Obispo, California, USA
| | - Derek Gragson
- Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo, California, USA
| | - Rafael Jiménez-Flores
- Dairy Products Technology Center, California Polytechnic State University, San Luis Obispo, California, USA
| | - David W. Everett
- Department of Food Science, University of Otago, Dunedin, New Zealand
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29
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Vaezian B, Anderton CR, Kraft ML. Discriminating and Imaging Different Phosphatidylcholine Species within Phase-Separated Model Membranes by Principal Component Analysis of TOF-Secondary Ion Mass Spectrometry Images. Anal Chem 2010; 82:10006-14. [DOI: 10.1021/ac101640c] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Bita Vaezian
- Departments of Chemical and Biomolecular Engineering and Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Christopher R. Anderton
- Departments of Chemical and Biomolecular Engineering and Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Mary L. Kraft
- Departments of Chemical and Biomolecular Engineering and Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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30
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Material properties of lipid microdomains: force-volume imaging study of the effect of cholesterol on lipid microdomain rigidity. Biophys J 2010; 99:834-44. [PMID: 20682261 DOI: 10.1016/j.bpj.2010.04.072] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 04/27/2010] [Accepted: 04/30/2010] [Indexed: 11/22/2022] Open
Abstract
The effect of cholesterol (CHOL) on the material properties of supported lipid bilayers composed of lipid mixtures that mimic the composition of lipid microdomains was studied by force-volume (FV) imaging under near-physiological conditions. These studies were carried out with lipid mixtures of dioleoylphosphatidylcholine, dioleoylphosphatidylserine, and sphingomyelin. FV imaging enabled simultaneous topology and force measurements of sphingomyelin-rich domains (higher domain (HD)) and phospholipid-rich domains (lower domain (LD)), which allowed quantitative measurement of the force needed to puncture the lipid bilayer with or without CHOL. The force required to penetrate the various domains of the bilayer was probed using high- and low-ionic-strength buffers as a function of increasing amounts of CHOL in the bilayer. The progressive addition of CHOL also led to a decreasing height difference between HD and LD. FV imaging further demonstrated a lack of adhesion between the atomic force microscope tip and the HD or LD at loads below the breakthrough force. These results can lead to a better understanding of the role that CHOL plays in the mechanical properties of cellular membranes in modulating membrane rigidity, which has important implications for cellular mechanotransduction.
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31
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Anderton CR, Lou K, Weber PK, Hutcheon ID, Kraft ML. Correlated AFM and NanoSIMS imaging to probe cholesterol-induced changes in phase behavior and non-ideal mixing in ternary lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:307-15. [PMID: 20883665 DOI: 10.1016/j.bbamem.2010.09.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 09/09/2010] [Accepted: 09/20/2010] [Indexed: 12/13/2022]
Abstract
Cholesterol is believed to be an important component in compositionally distinct lipid domains in the cellular plasma membrane, which are referred to as lipid rafts. Insight into how cholesterol influences the interactions that contribute to plasma membrane organization can be acquired from model lipid membranes. Here we characterize the lipid mixing and phase behavior exhibited by (15)N-dilaurolyphosphatidycholine ((15)N-DLPC)/deuterated distearoylphosphatiylcholine (D(70)-DSPC) membranes with various amounts of cholesterol (0, 3, 7, 15 or 19mol%) at room temperature. The microstructures and compositions of individual membrane domains were determined by imaging the same membrane locations with both atomic force microscopy (AFM) and high-resolution secondary ion mass spectrometry (SIMS) performed with a Cameca NanoSIMS 50. As the cholesterol composition increased from 0 to 19mol%, the circular ordered domains became more elongated, and the amount of (15)N-DLPC in the gel-phase domains remained constant at 6-7mol%. Individual and micron-sized clusters of nanoscopic domains enriched in D(70)-DSPC were abundant in the 19mol% cholesterol membrane. AFM imaging showed that these lipid domains had irregular borders, indicating that they were gel-phase domains, and not non-ideally mixed lipid clusters or nanoscopic liquid-ordered domains.
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Affiliation(s)
- Christopher R Anderton
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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32
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Largueze JB, Kirat KE, Morandat S. Preparation of an electrochemical biosensor based on lipid membranes in nanoporous alumina. Colloids Surf B Biointerfaces 2010; 79:33-40. [DOI: 10.1016/j.colsurfb.2010.03.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 03/17/2010] [Accepted: 03/17/2010] [Indexed: 12/25/2022]
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33
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Giocondi MC, Yamamoto D, Lesniewska E, Milhiet PE, Ando T, Le Grimellec C. Surface topography of membrane domains. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:703-18. [DOI: 10.1016/j.bbamem.2009.09.015] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Revised: 09/11/2009] [Accepted: 09/20/2009] [Indexed: 12/24/2022]
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Nanomechanics of lipid bilayers by force spectroscopy with AFM: A perspective. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:741-9. [DOI: 10.1016/j.bbamem.2009.12.019] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2009] [Revised: 12/16/2009] [Accepted: 12/20/2009] [Indexed: 01/11/2023]
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35
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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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36
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Probing material properties of polymeric surface layers with tapping mode AFM: Which cantilever spring constant, tapping amplitude and amplitude set point gives good image contrast and minimal surface damage? Ultramicroscopy 2010; 110:313-9. [DOI: 10.1016/j.ultramic.2010.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 11/19/2009] [Accepted: 01/12/2010] [Indexed: 11/22/2022]
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37
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Briand E, Zäch M, Svedhem S, Kasemo B, Petronis S. Combined QCM-D and EIS study of supported lipid bilayer formation and interaction with pore-forming peptides. Analyst 2010; 135:343-50. [DOI: 10.1039/b918288h] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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Xiong Y, Lee AC, Suter DM, Lee GU. Topography and nanomechanics of live neuronal growth cones analyzed by atomic force microscopy. Biophys J 2009; 96:5060-72. [PMID: 19527666 DOI: 10.1016/j.bpj.2009.03.032] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 03/01/2009] [Accepted: 03/26/2009] [Indexed: 10/20/2022] Open
Abstract
Neuronal growth cones are motile structures located at the end of axons that translate extracellular guidance information into directional movements. Despite the important role of growth cones in neuronal development and regeneration, relatively little is known about the topography and mechanical properties of distinct subcellular growth cone regions under live conditions. In this study, we used the AFM to study the P domain, T zone, and C domain of live Aplysia growth cones. The average height of these regions was calculated from contact mode AFM images to be 183 +/- 33, 690 +/- 274, and 1322 +/- 164 nm, respectively. These findings are consistent with data derived from dynamic mode images of live and contact mode images of fixed growth cones. Nano-indentation measurements indicate that the elastic moduli of the C domain and T zone ruffling region ranged between 3-7 and 7-23 kPa, respectively. The range of the measured elastic modulus of the P domain was 10-40 kPa. High resolution images of the P domain suggest its relatively high elastic modulus results from a dense meshwork of actin filaments in lamellipodia and from actin bundles in the filopodia. The increased mechanical stiffness of the P and T domains is likely important to support and transduce tension that develops during growth cone steering.
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Affiliation(s)
- Ying Xiong
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana, USA
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39
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Sullan RMA, Li JK, Zou S. Direct correlation of structures and nanomechanical properties of multicomponent lipid bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:7471-7. [PMID: 19292499 DOI: 10.1021/la900395w] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Exploring the fine structures and physicochemical properties of physiologically relevant membranes is crucial to understanding biological membrane functions including membrane mechanical stability. We report a direct correlation of the self-organized structures exhibited in phase-segregated supported lipid bilayers consisting of dioleoylphosphatidylcholine/egg sphingomyelin/cholesterol (DEC) in the absence and presence of ceramide (DEC-Ceramide) with their nanomechanical properties using AFM imaging and high-resolution force mapping. Direct incorporation of ceramide into phase-segregated supported lipid bilayers formed ceramide-enriched domains, where the height topography was found to be imaging setpoint dependent. In contrast, liquid ordered domains in both DEC and DEC-Ceramide presented similar heights regardless of AFM imaging settings. Owing to its capability for simultaneous determination of the topology and interaction forces, AFM-based force mapping was used in our study to directly correlate the structures and mechanical responses of different coexisting phases. The intrinsic breakthrough forces, regarded as fingerprints of bilayer stability, along with elastic moduli, adhesion forces, and indentation of the different phases in the bilayers were systematically determined on the nanometer scale, and the results were presented as two-dimensional visual maps using a self-developed code for force curves batch analysis. The mechanical stability and compactness were increased in both liquid ordered domains and fluid disordered phases of DEC-Ceramide, attributed to the influence of ceramide in the organization of the bilayer, as well as to the displacement of cholesterol as a result of the generation of ceramide-enriched domains. The use of AFM force mapping in studying phase segregation of multicomponent lipid membrane systems is a valuable complement to other biophysical techniques such as imaging and spectroscopy, as it provides unprecedented insight into lipid membrane mechanical properties and functions.
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Affiliation(s)
- Ruby May A Sullan
- Steacie Institute for Molecular Sciences, National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
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40
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Creczynski-Pasa TB, Millone MAD, Munford ML, de Lima VR, Vieira TO, Benitez GA, Pasa AA, Salvarezza RC, Vela ME. Self-assembled dithiothreitol on Au surfaces for biological applications: phospholipid bilayer formation. Phys Chem Chem Phys 2008; 11:1077-84. [PMID: 19543605 DOI: 10.1039/b811964c] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Self-assembly of dithiothreitol (DTT) on Au(111) from solution deposition has been studied by X-ray photoelectron spectroscopy and electrochemical data. DTT molecules self-assemble on Au(111) in a lying-down configuration irrespective of the concentration and temperature. XPS and electrochemical data indicate a DTT surface coverage of theta approximately 0.16 with two S-head-Au covalent bonds per DTT molecule. The DTT monolayer turns the Au surface hydrophilic enough to allow the formation of fluid dimyristoylphosphatidylcholine (DMPC) bilayer domains by vesicle fusion as revealed by in situ atomic force imaging. Methylene blue (MB) and flavin adenine dinucleotide (FAD) have been used as probes to study molecule transport across the bilayer.
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Affiliation(s)
- Tânia B Creczynski-Pasa
- Departamento de Ciências Farmacêuticas and Departamento de Física, UFSC, C. P. 476, Florianópolis, 88.040-900, Brazil.
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41
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Picas L, Montero MT, Morros A, Oncins G, Hernández-Borrell J. Phase Changes in Supported Planar Bilayers of 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine. J Phys Chem B 2008; 112:10181-7. [DOI: 10.1021/jp8037522] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Laura Picas
- Departament de Fisicoquímica, Facultat de Farmàcia UB, 08028-Barcelona, Spain, Unitat de Biofísica, Departament de Bioquímica i Biología Molecular, Facultat de Medicina, UAB, 08193-Bellaterra (Barcelona), Spain, and Serveis Científico Tècnics UB, 08028-Barcelona, Spain
| | - M. Teresa Montero
- Departament de Fisicoquímica, Facultat de Farmàcia UB, 08028-Barcelona, Spain, Unitat de Biofísica, Departament de Bioquímica i Biología Molecular, Facultat de Medicina, UAB, 08193-Bellaterra (Barcelona), Spain, and Serveis Científico Tècnics UB, 08028-Barcelona, Spain
| | - Antoni Morros
- Departament de Fisicoquímica, Facultat de Farmàcia UB, 08028-Barcelona, Spain, Unitat de Biofísica, Departament de Bioquímica i Biología Molecular, Facultat de Medicina, UAB, 08193-Bellaterra (Barcelona), Spain, and Serveis Científico Tècnics UB, 08028-Barcelona, Spain
| | - Gerard Oncins
- Departament de Fisicoquímica, Facultat de Farmàcia UB, 08028-Barcelona, Spain, Unitat de Biofísica, Departament de Bioquímica i Biología Molecular, Facultat de Medicina, UAB, 08193-Bellaterra (Barcelona), Spain, and Serveis Científico Tècnics UB, 08028-Barcelona, Spain
| | - Jordi Hernández-Borrell
- Departament de Fisicoquímica, Facultat de Farmàcia UB, 08028-Barcelona, Spain, Unitat de Biofísica, Departament de Bioquímica i Biología Molecular, Facultat de Medicina, UAB, 08193-Bellaterra (Barcelona), Spain, and Serveis Científico Tècnics UB, 08028-Barcelona, Spain
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42
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Oncins G, Picas L, Hernández-Borrell J, Garcia-Manyes S, Sanz F. Thermal response of Langmuir-Blodgett films of dipalmitoylphosphatidylcholine studied by atomic force microscopy and force spectroscopy. Biophys J 2007; 93:2713-25. [PMID: 17586574 PMCID: PMC1989725 DOI: 10.1529/biophysj.107.110916] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Accepted: 06/15/2007] [Indexed: 11/18/2022] Open
Abstract
The topographic evolution of supported dipalmitoylphosphatidylcholine (DPPC) monolayers with temperature has been followed by atomic force microscopy in liquid environment, revealing the presence of only one phase transition event at approximately 46 degrees C. This finding is a direct experimental proof that the two phase transitions observed in the corresponding bilayers correspond to the individual phase transition of the two leaflets composing the bilayer. The transition temperature and its dependency on the measuring medium (liquid saline solution or air) is discussed in terms of changes in van der Waals, hydration, and hydrophobic/hydrophilic interactions, and it is directly compared with the transition temperatures observed in the related bilayers under the same experimental conditions. Force spectroscopy allows us to probe the nanomechanical properties of such monolayers as a function of temperature. These measurements show that the force needed to puncture the monolayers is highly dependent on the temperature and on the phospholipid phase, ranging from 120+/-4 pN at room temperature (liquid condensed phase) to 49+/-2 pN at 65 degrees C (liquid expanded phase), which represents a two orders-of-magnitude decrease respective to the forces needed to puncture DPPC bilayers. The topographic study of the monolayers in air around the transition temperature revealed the presence of boundary domains in the monolayer surface forming 120 degrees angles between them, thus suggesting that the cooling process from the liquid-expanded to the liquid-condensed phase follows a nucleation and growth mechanism.
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Affiliation(s)
- Gerard Oncins
- Department of Physical Chemistry, Chemistry Faculty, University of Barcelona and Institut de Bioenginyeria de Catalunya, Barcelona, Spain
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43
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Yoder NC, Kalsani V, Schuy S, Vogel R, Janshoff A, Kumar K. Nanoscale patterning in mixed fluorocarbon-hydrocarbon phospholipid bilayers. J Am Chem Soc 2007; 129:9037-43. [PMID: 17602478 PMCID: PMC2507729 DOI: 10.1021/ja070950l] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A growing body of literature suggests that fluorocarbons can direct self-assembly within hydrocarbon environments. We report here the fabrication and characterization of supported lipid bilayers (SLBs) composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and a synthetic, fluorocarbon-functionalized analogue, 1. AFM investigation of these model membranes reveals an intricate, composition-dependent domain structure consisting of approximately 50 nm stripes interspersed between approximately 1 microm sized domains. Although DSC of 1 showed a phase transition near room temperature, DSC of DPPC:1 mixtures exhibited complex phase behavior suggesting domain segregation. Finally, temperature-dependent AFM of DPPC:1 bilayers shows that, while the stripe structures can be melted above the Tm of 1, the stripes and domains result from immiscibility of the hydrocarbon and fluorocarbon lipid gel phases. Fluorination appears to be a promising strategy for chemical self-assembly in two dimensions. In particular, because no modification is made to the lipid headgroups, it may be useful for nanopatterning biologically relevant ligands on bilayers in vitro or in living cells.
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Affiliation(s)
| | | | - Steffen Schuy
- Institute for Physical Chemistry, University of Mainz, 55128 Mainz, Germany
| | - Reiner Vogel
- Institute for Molecular Medicine and Cell Research, University of Freiburg, 79104 Freiburg, Germany
| | - Andreas Janshoff
- Institute for Physical Chemistry, University of Mainz, 55128 Mainz, Germany
| | - Krishna Kumar
- Department of Chemistry, Tufts University, Medford MA 02155
- Cancer Center, Tufts-New England Medical Center, Boston MA 02110
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44
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Garcia-Manyes S, Domènech O, Sanz F, Montero MT, Hernandez-Borrell J. Atomic force microscopy and force spectroscopy study of Langmuir–Blodgett films formed by heteroacid phospholipids of biological interest. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1190-8. [PMID: 17376401 DOI: 10.1016/j.bbamem.2007.02.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 01/17/2007] [Accepted: 02/01/2007] [Indexed: 01/19/2023]
Abstract
Langmuir-Blodgett (LB) films of two heteroacid phospholipids of biological interest 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), as well as a mixed monolayer with chi(POPC)=0.4, were transferred onto mica in order to investigate by a combination of atomic force microscopy (AFM) and force spectroscopy (FS) their height, and particularly, their nanomechanical properties. AFM images of such monolayers extracted at 30 mN m(-1) revealed a smooth and defect-free topography except for the POPE monolayer. Since scratching such soft monolayers in contact mode was proved unsuccessful, their molecular height was measured by means of the width of the jump present in the respective force-extension curves. While for pure POPC a small jump occurs near zero force, for the mixed monolayer with chi(POPC)=0.4 the jump occurs at approximately 800 pN. Widths of approximately 2 nm could be established for POPC and chi(POPC)=0.4, but not for POPE monolayer at this extracting pressure. Such different mechanical stability allowed us to directly measure the threshold area/lipid range value needed to induce mechanical stability to the monolayers. AFM imaging and FS were next applied to get further structural and mechanical insight into the POPE phase transition (LC-LC') occurring at pressures >36.5 mN m(-1). This phase transition was intimately related to a sudden decrease in the area/molecule value, resulting in a jump in the force curve occurring at high force ( approximately 1.72 nN). FS reveals to be the unique experimental technique able to unveil structural and nanomechanical properties for such soft phospholipid monolayers. The biological implications of the nanomechanical properties of the systems under investigation are discussed considering that the annular phospholipids region of some transmembrane proteins is enriched in POPE.
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Affiliation(s)
- Sergi Garcia-Manyes
- Departament de Química Física, Facultat de Química, Universitat de Barcelona, E-08028-Barcelona, Spain
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45
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Simon A, Girard-Egrot A, Sauter F, Pudda C, Picollet D'Hahan N, Blum L, Chatelain F, Fuchs A. Formation and stability of a suspended biomimetic lipid bilayer on silicon submicrometer-sized pores. J Colloid Interface Sci 2007; 308:337-43. [PMID: 17275017 DOI: 10.1016/j.jcis.2006.11.050] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 11/28/2006] [Accepted: 11/29/2006] [Indexed: 11/18/2022]
Abstract
We report the fabrication of a thin silicon membrane with an array of micrometer and submicrometer pores that acts as a scaffold for suspending a lipid bilayer. We successfully deposited a lipid bilayer by the Langmuir-Blodgett method on a synthetic silicon membrane bearing arrays of pores with sizes of 1000, 650, and 300 nm. Topographic images obtained by AFM showed a suspended lipid film spanning the pores, whatever the pore size. Higher stability of bilayers supported on smaller pores was shown by AFM characterization. These results represent an important first step to creating a biomimetic environment to study cell membrane dynamics and/or in developing a biosensor.
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Affiliation(s)
- A Simon
- CEA, DSV/DRDC/Biopuces, 38 054 Grenoble cedex 9, France.
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46
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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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47
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Grzywa EL, Lee AC, Lee GU, Suter DM. High-resolution analysis of neuronal growth cone morphology by comparative atomic force and optical microscopy. ACTA ACUST UNITED AC 2007; 66:1529-43. [PMID: 17058186 DOI: 10.1002/neu.20318] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Neuronal growth cones are motile sensory structures at the tip of axons, transducing guidance information into directional movements towards target cells. The morphology and dynamics of neuronal growth cones have been well characterized with optical techniques; however, very little quantitative information is available on the three-dimensional structure and mechanical properties of distinct subregions. In the present study, we imaged the large Aplysia growth cones after chemical fixation with the atomic force microscope (AFM) and directly compared our data with images acquired by light microscopy methods. Constant force imaging in contact mode in combination with force-distant measurements revealed an average height of 200 nm for the peripheral (P) domain, 800 nm for the transition (T) zone, and 1200 nm for the central (C) domain, respectively. The AFM images show that the filopodial F-actin bundles are stiffer than surrounding F-actin networks. Enlarged filopodia tips are 60 nm higher than the corresponding shafts. Measurements of the mechanical properties of the specific growth cone regions with the AFM revealed that the T zone is stiffer than the P and the C domain. Direct comparison of AFM and optical data acquired by differential interference contrast and fluorescence microscopy revealed a good correlation between these imaging methods. However, the AFM provides height and volume information at higher resolution than fluorescence methods frequently used to estimate the volume of cellular compartments. These findings suggest that AFM measurements on live growth cones will provide a quantitative understanding of how proteins can move between different growth cone regions.
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Affiliation(s)
- Emilie L Grzywa
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907-2100, USA
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48
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Alessandrini A, Valdrè G, Valdrè U, Muscatello U. Defects in ordered aggregates of cardiolipin visualized by atomic force microscopy. Chem Phys Lipids 2007; 146:111-24. [PMID: 17274972 DOI: 10.1016/j.chemphyslip.2007.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 01/01/2007] [Accepted: 01/09/2007] [Indexed: 11/23/2022]
Abstract
The formation and the nature of defects in ordered aggregates of cardiolipin (tetra acyl diphosphatidylglycerol) supported on solid substrates have been investigated by atomic force microscopy (AFM). The experiments were performed on two model systems, i.e. three-dimensional liquid crystals dispersed in water and partially de-hydrated on a hydrophilic surface, and two-dimensional films of molecules self-assembled onto an isotropic hydrophobic surface. Defects were induced both by varying the preparation temperature and by treatment with specific chemicals known to modify the order parameters in natural and artificial membranes, specifically: 2,4-dinitro-phenol (DNP) and pentachloro-phenol (PCP). The effect of lipid oxidation on the nanocrystalline order was also investigated. The images obtained by AFM allow to characterize the type of defects and their local density at nanoscale level. They also provide additional information to differentiate the specific role of acyl chains and polar heads in the process of lipid self-organization.
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Affiliation(s)
- Andrea Alessandrini
- CNR-INFM-S3 NanoStructures and BioSystems at Surfaces, Via Campi 213/A, I-41100, Modena, Italy.
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49
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Yang Y, Mayer KM, Hafner JH. Quantitative membrane electrostatics with the atomic force microscope. Biophys J 2006; 92:1966-74. [PMID: 17158563 PMCID: PMC1861775 DOI: 10.1529/biophysj.106.093328] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The atomic force microscope (AFM) is sensitive to electric double layer interactions in electrolyte solutions, but provides only a qualitative view of interfacial electrostatics. We have fully characterized silicon nitride probe tips and other experimental parameters to allow a quantitative electrostatic analysis by AFM, and we have tested the validity of a simple analytical force expression through numerical simulations. As a test sample, we have measured the effective surface charge density of supported zwitterionic dioleoylphosphatidylcholine membranes with a variable fraction of anionic dioleoylphosphatidylserine. The resulting surface charge density and surface potential values are in quantitative agreement with those predicted by the Gouy-Chapman-Stern model of membrane charge regulation, but only when the numerical analysis is employed. In addition, we demonstrate that the AFM can detect double layer forces at a separation of several screening lengths, and that the probe only perturbs the membrane surface potential by <2%. Finally, we demonstrate 50-nm resolution electrostatic mapping on heterogeneous model membranes with the AFM. This novel combination of capabilities demonstrates that the AFM is a unique and powerful probe of membrane electrostatics.
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Affiliation(s)
- Yi Yang
- Department of Physics & Astronomy, Rice University, Houston, Texas, USA
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50
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Howland MC, Szmodis AW, Sanii B, Parikh AN. Characterization of physical properties of supported phospholipid membranes using imaging ellipsometry at optical wavelengths. Biophys J 2006; 92:1306-17. [PMID: 17142265 PMCID: PMC1783900 DOI: 10.1529/biophysj.106.097071] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Subnanometer-scale vertical z-resolution coupled with large lateral area imaging, label-free, noncontact, and in situ advantages make the technique of optical imaging ellipsometry (IE) highly suitable for quantitative characterization of lipid bilayers supported on oxide substrates and submerged in aqueous phases. This article demonstrates the versatility of IE in quantitative characterization of structural and functional properties of supported phospholipid membranes using previously well-characterized examples. These include 1), a single-step determination of bilayer thickness to 0.2 nm accuracy and large-area lateral uniformity using photochemically patterned single 1,2-dimyristoyl-sn-glycero-3-phosphocholine bilayers; 2), hydration-induced spreading kinetics of single-fluid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers to illustrate the in situ capability and image acquisition speed; 3), a large-area morphological characterization of phase-separating binary mixtures of 1,2-dilauroyl-sn-glycero-3-phosphocholine and galactosylceramide; and 4), binding of cholera-toxin B subunits to GM1-incorporating bilayers. Additional insights derived from these ellipsometric measurements are also discussed for each of these applications. Agreement with previous studies confirms that IE provides a simple and convenient tool for a routine, quantitative characterization of these membrane properties. Our results also suggest that IE complements more widely used fluorescence and scanning probe microscopies by combining large-area measurements with high vertical resolution without the use of labeled lipids.
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Affiliation(s)
- Michael C Howland
- Chemical Engineering and Materials Science Group, University of California, Davis, California 95616, USA
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