1
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Yahyazadeh Shourabi A, Kieffer R, de Jong D, Tam D, Aubin-Tam ME. Mechanical characterization of freestanding lipid bilayers with temperature-controlled phase. SOFT MATTER 2024; 20:8524-8537. [PMID: 39417217 DOI: 10.1039/d4sm00706a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2024]
Abstract
Coexistence of lipid domains in cell membranes is associated with vital biological processes. Here, we investigate two such membranes: a multi-component membrane composed of DOPC and DPPC lipids with gel and fluid separated domains, and a single component membrane composed of PMPC lipids forming ripples. We characterize their mechanical properties below their melting point, where ordered and disordered regions coexist, and above their melting point, where they are in fluid phase. To conduct these inquiries, we create lipid bilayers in a microfluidic chip interfaced with a heating system and optical tweezers. The chip features a bubble trap and enables high-throughput formation of planar bilayers. Optical tweezers experiments reveal interfacial hydrodynamics (fluid-slip) and elastic properties (membrane tension and bending rigidity) at various temperatures. For PMPC bilayers, we demonstrate a higher fluid slip at the interface in the fluid-phase compared to the ripple phase, while for the DOPC:DPPC mixture, similar fluid slip is measured below and above the transition point. Membrane tension for both compositions increases after thermal fluidization. Bending rigidity is also measured using the forces required to extend a lipid nanotube pushed out of the freestanding membranes. This novel temperature-controlled microfluidic platform opens numerous possibilities for thermomechanical studies on freestanding planar membranes.
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Affiliation(s)
- Arash Yahyazadeh Shourabi
- Department of Bionanoscience, Kavli institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands.
| | - Roland Kieffer
- Department of Bionanoscience, Kavli institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands.
| | - Djanick de Jong
- Department of Bionanoscience, Kavli institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands.
| | - Daniel Tam
- Laboratory for Aero and Hydrodynamics, Faculty of Mechanical Engineering, Delft University of Technology, 2628 CD, Delft, The Netherlands.
| | - Marie-Eve Aubin-Tam
- Department of Bionanoscience, Kavli institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands.
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2
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Wan H, Jeon G, Grason GM, Santore MM. Thermal preconditioning of membrane stress to control the shapes of ultrathin crystals. SOFT MATTER 2024; 20:6984-6994. [PMID: 39171459 DOI: 10.1039/d4sm00739e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
We employ the phospholipid bilayer membranes of giant unilamellar vesicles as a free-standing environment for the growth of membrane-integrated ultrathin phospholipid crystals possessing a variety of shapes with 6-fold symmetry. Crystal growth within vesicle membranes, where more elaborate shapes grow on larger vesicles is dominated by the bending energy of the membrane itself, creating a means to manipulate crystal morphology. Here we demonstrate how cooling rate preconditions the membrane tension before nucleation, in turn regulating nucleation and growth, and directing the morphology of crystals by the time they are large enough to be visualized. The crystals retain their shapes during further growth through the two phase region. Experiments demonstrate this behavior for single crystals growing within the membrane of each vesicle, ultimately comprising up to 13% of the vesicle area and length scales of up to 50 microns. A model for stress evolution, employing only physical property data, reveals how the competition between thermal membrane contraction and water diffusion from tensed vesicles produces a size- and time-dependence of the membrane tension as a result of cooling history. The tension, critical in the contribution of bending energy in the fluid membrane regions, in turn selects for crystal shape for vesicles of a given size. The model reveals unanticipated behaviors including a low steady state tension on small vesicles that allows compact domains to develop, rapid tension development on large vesicles producing flower-shaped domains, and a stress relaxation through water diffusion across the membrane with a time constant scaling as the square of the vesicle radius, consistent with measurable tensions only in the largest vesicles.
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Affiliation(s)
- Hao Wan
- Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA.
| | - Geunwoong Jeon
- Department of Physics University of Massachusetts, 710 N Pleasant St, Amherst, MA 01003, USA
| | - Gregory M Grason
- Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA.
| | - Maria M Santore
- Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA.
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3
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Prince A, Tiwari A, Mandal T, Koiri D, Meher G, Sinha DK, Saleem M. Lipid Specificity of the Fusion of Bacterial Extracellular Vesicles with the Host Membrane. J Phys Chem B 2024; 128:8116-8130. [PMID: 38981091 DOI: 10.1021/acs.jpcb.4c02321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2024]
Abstract
Bacterial membrane vesicles (MVs) facilitate the long-distance delivery of virulence factors crucial for pathogenicity. The entry and trafficking mechanisms of virulence factors inside host cells are recently emerging; however, whether bacterial MVs can fuse and modulate the physicochemical properties of the host lipid membrane and membrane lipid parameter for fusion remains unknown. In this study, we reconstituted the interaction of bacterial MVs with host cell lipid membranes and quantitatively showed that bacterial MV interaction increases the fluidity, dipole potential, and compressibility of a biologically relevant multicomponent host membrane upon fusion. The presence of cylindrical lipids, such as phosphatidylcholine, and a moderate acyl chain length of C16 help the MV interaction. While significant binding of bacterial MVs to the raft-like lipid membranes with phase-separated regions of the membrane was observed, however, MVs prefer binding to the liquid-disordered regions of the membrane. Furthermore, the elevated levels of cholesterol tend to hinder the interaction of bacterial MVs, as evident from the favorable excess Gibbs free energy of mixing bacterial MVs with host lipid membranes. The findings provide new insights that might have implications for the regulation of host machinery by bacterial pathogens through manipulation of the host membrane properties.
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Affiliation(s)
- Ashutosh Prince
- Department of Life Sciences, National Institute of Technology, Rourkela 769008, India
| | - Anuj Tiwari
- Department of Life Sciences, National Institute of Technology, Rourkela 769008, India
| | - Titas Mandal
- Department of Physical Biochemistry, University of Potsdam, Potsdam 14476, Germany
| | - Debraj Koiri
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar 752050, India
- Homi Bhabha National Institute, Mumbai 400094, India
| | - Geetanjali Meher
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar 752050, India
- Homi Bhabha National Institute, Mumbai 400094, India
| | - Deepak Kumar Sinha
- Department of Biological Chemistry, Indian Association for the Cultivation of Sciences, Kolkata 700032, India
| | - Mohammed Saleem
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar 752050, India
- Homi Bhabha National Institute, Mumbai 400094, India
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4
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Sirch MM, Kamenac A, Neidinger SV, Wixforth A, Westerhausen C. Phase-State-Dependent Silica Nanoparticle Uptake of Giant Unilamellar Vesicles. J Phys Chem B 2024; 128:7172-7179. [PMID: 38995207 DOI: 10.1021/acs.jpcb.4c02383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
We quantify endocytosis-like nanoparticle (NP) uptake of model membranes as a function of temperature and, therefore, phase state. As model membranes, we use giant unilamellar vesicles (GUV) consisting of 1,2-dipentadecanoyl-sn-glycero-3-phosphocholine (15:0 PC). Time-series micrographs of the vesicle shrinkage show uptake rates that are a highly nonlinear function of temperature. A global maximum appears close to the main structural phase transition at T = Tm + 3 K = 37 °C and a minor peak at the pretransition T = Tp = 22 °C. The quality of linear fits to the shrinkage, and thus uptake kinetics, reveals a deviation from the linear trend at the vesicle shrinkage peaks. Taking values for the bending modulus as a function of temperature from literature and Helfrich's model allows us to draw qualitative conclusions on the membrane tension and the adhesion of the NP to the membrane as a function of temperature. These findings provide valuable insights into the dynamic interplay between temperature, membrane phase transitions, and NP uptake, shedding light on the complex behavior of biological membranes.
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Affiliation(s)
- Manuel M Sirch
- Institute of Theoretical Medicine, Physiology, University of Augsburg, Augsburg 86159, Germany
- Institute of Physics, University of Augsburg, Augsburg 86159, Germany
| | - Andrej Kamenac
- Institute of Theoretical Medicine, Physiology, University of Augsburg, Augsburg 86159, Germany
- Institute of Physics, University of Augsburg, Augsburg 86159, Germany
| | - Simon V Neidinger
- Institute of Theoretical Medicine, Physiology, University of Augsburg, Augsburg 86159, Germany
- Institute of Physics, University of Augsburg, Augsburg 86159, Germany
| | - Achim Wixforth
- Institute of Physics, University of Augsburg, Augsburg 86159, Germany
- Center for NanoScience (CeNS), Ludwig-Maximilians-Universität Munich, Munich 80799, Germany
| | - Christoph Westerhausen
- Institute of Theoretical Medicine, Physiology, University of Augsburg, Augsburg 86159, Germany
- Institute of Physics, University of Augsburg, Augsburg 86159, Germany
- Center for NanoScience (CeNS), Ludwig-Maximilians-Universität Munich, Munich 80799, Germany
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5
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Jeon G, Fagnoni J, Wan H, Santore MM, Grason GM. Shape equilibria of vesicles with rigid planar inclusions. SOFT MATTER 2024; 20:5754-5768. [PMID: 38984409 DOI: 10.1039/d4sm00439f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2024]
Abstract
Motivated by recent studies of two-phase lipid vesicles possessing 2D solid domains integrated within a fluid bilayer phase, we study the shape equilibria of closed vesicles possessing a single planar, circular inclusion. While 2D solid elasticity tends to expel Gaussian curvature, topology requires closed vesicles to maintain an average, non-zero Gaussian curvature leading to an elementary mechanism of shape frustration that increases with inclusion size. We study elastic ground states of the Helfrich model of the fluid-planar composite vesicles, analytically and computationally, as a function of planar fraction and reduced volume. Notably, we show that incorporation of a planar inclusion of only a few percent dramatically shifts the ground state shapes of vesicles from predominantly prolate to oblate, and moreover, shifts the optimal surface-to-volume ratio far from spherical shapes. We show that for sufficiently small planar inclusions, the elastic ground states break symmetry via a complex variety of asymmetric oblate, prolate, and triaxial shapes, while inclusion sizes above about 8% drive composite vesicles to adopt axisymmetric oblate shapes. These predictions cast useful light on the emergent shape and mechanical responses of fluid-solid composite vesicles.
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Affiliation(s)
- Geunwoong Jeon
- Department of Physics, University of Massachusetts, Amherst, MA 01003, USA
| | - Justin Fagnoni
- Department of Physics, University of Massachusetts, Amherst, MA 01003, USA
| | - Hao Wan
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA.
| | - Maria M Santore
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA.
| | - Gregory M Grason
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA.
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6
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Reagle T, Xie Y, Li Z, Carnero W, Baumgart T. Methyl-β-cyclodextrin asymmetrically extracts phospholipid from bilayers, granting tunable control over differential stress in lipid vesicles. SOFT MATTER 2024; 20:4291-4307. [PMID: 38758097 PMCID: PMC11135146 DOI: 10.1039/d3sm01772a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 05/01/2024] [Indexed: 05/18/2024]
Abstract
Lipid asymmetry - that is, a nonuniform lipid distribution between the leaflets of a bilayer - is a ubiquitous feature of biomembranes and is implicated in several cellular phenomena. Differential tension - that is, unequal lateral monolayer tensions comparing the leaflets of a bilayer- is closely associated with lipid asymmetry underlying these varied roles. Because differential tension is not directly measurable in combination with the fact that common methods to adjust this quantity grant only semi-quantitative control over it, a detailed understanding of lipid asymmetry and differential tension are impeded. To overcome these challenges, we leveraged reversible complexation of phospholipid by methyl-β-cyclodextrin (mbCD) to tune the direction and magnitude of lipid asymmetry in synthetic vesicles. Lipid asymmetry generated in our study induced (i) vesicle shape changes and (ii) gel-liquid phase coexistence in 1-component vesicles. By applying mass-action considerations to interpret our findings, we discuss how this approach provides access to phospholipid thermodynamic potentials in bilayers containing lipid asymmetry (which are coupled to the differential tension of a bilayer). Because lipid asymmetry yielded by our approach is (i) tunable and (ii) maintained over minute to hour timescales, we anticipate that this approach will be a valuable addition to the experimental toolbox for systematic investigation into the biophysical role(s) of lipid asymmetry (and differential tension).
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Affiliation(s)
- Tyler Reagle
- University of Pennsylvania, Chemistry Department, 231 South 34th Street, Philadelphia, PA, 19104, USA.
| | - Yuxin Xie
- University of Pennsylvania, Chemistry Department, 231 South 34th Street, Philadelphia, PA, 19104, USA.
| | - Zheyuan Li
- University of Pennsylvania, Chemistry Department, 231 South 34th Street, Philadelphia, PA, 19104, USA.
| | - Warner Carnero
- University of Pennsylvania, Chemistry Department, 231 South 34th Street, Philadelphia, PA, 19104, USA.
| | - Tobias Baumgart
- University of Pennsylvania, Chemistry Department, 231 South 34th Street, Philadelphia, PA, 19104, USA.
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7
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Wan H, Jeon G, Xin W, Grason GM, Santore MM. Flower-shaped 2D crystals grown in curved fluid vesicle membranes. Nat Commun 2024; 15:3442. [PMID: 38658581 PMCID: PMC11043355 DOI: 10.1038/s41467-024-47844-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 04/11/2024] [Indexed: 04/26/2024] Open
Abstract
The morphologies of two-dimensional (2D) crystals, nucleated, grown, and integrated within 2D elastic fluids, for instance in giant vesicle membranes, are dictated by an interplay of mechanics, permeability, and thermal contraction. Mitigation of solid strain drives the formation of crystals with vanishing Gaussian curvature (i.e., developable domain shapes) and, correspondingly, enhanced Gaussian curvature in the surrounding 2D fluid. However, upon cooling to grow the crystals, large vesicles sustain greater inflation and tension because their small area-to-volume ratio slows water permeation. As a result, more elaborate shapes, for instance, flowers with bendable but inextensible petals, form on large vesicles despite their more gradual curvature, while small vesicles harbor compact planar crystals. This size dependence runs counter to the known cumulative growth of strain energy of 2D colloidal crystals on rigid spherical templates. This interplay of intra-membrane mechanics and processing points to the scalable production of flexible molecular crystals of controllable complex shape.
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Affiliation(s)
- Hao Wan
- Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA, 01003, USA
| | - Geunwoong Jeon
- Department of Physics, University of Massachusetts, 710 N. Pleasant Street, Amherst, MA, 01003, USA
| | - Weiyue Xin
- Department of Chemical Engineering, University of Massachusetts, 686 N. Pleasant Street, Amherst, MA, 01003, USA
| | - Gregory M Grason
- Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA, 01003, USA
| | - Maria M Santore
- Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA, 01003, USA.
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8
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Foley SL, Hossein A, Deserno M. Fluid-gel coexistence in lipid membranes under differential stress. Biophys J 2022; 121:2997-3009. [PMID: 35859420 PMCID: PMC9463654 DOI: 10.1016/j.bpj.2022.07.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/03/2022] [Accepted: 07/12/2022] [Indexed: 11/21/2022] Open
Abstract
A widely conserved property of many biological lipid bilayers is their asymmetry. In addition to having distinct compositions on its two sides, a membrane can also exhibit different tensions in its two leaflets, a state known as differential stress. Here, we examine how this stress can influence the phase behavior of the constituent lipid monolayers of a single-component membrane. For temperatures sufficiently close to, but still above, the main transition, molecular dynamics simulations show the emergence of finite gel domains within the compressed leaflet. We describe the thermodynamics of this phenomenon by adding two empirical single-leaflet free energies for the fluid-gel transition, each evaluated at its respective asymmetry-dependent lipid density. Finite size effects arising in simulation are included in the theory through a geometry-dependent interfacial term. Our model reproduces the phase coexistence observed in simulation. It could therefore be used to connect the "hidden variable" of differential stress to experimentally observable properties of the main phase transition. These ideas could be generalized to any first-order bilayer phase transition in the presence of asymmetry, including liquid-ordered/liquid-disordered phase separation.
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Affiliation(s)
- Samuel L Foley
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Amirali Hossein
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania; Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
| | - Markus Deserno
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania.
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9
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Anthony AA, Sahin O, Yapici MK, Rogers D, Honerkamp-Smith AR. Systematic measurements of interleaflet friction in supported bilayers. Biophys J 2022; 121:2981-2993. [PMID: 35754183 PMCID: PMC9388387 DOI: 10.1016/j.bpj.2022.06.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/23/2022] [Accepted: 06/22/2022] [Indexed: 11/20/2022] Open
Abstract
When lipid membranes curve or are subjected to strong shear forces, the two apposed leaflets of the bilayer slide past each other. The drag that one leaflet creates on the other is quantified by the coefficient of interleaflet friction, b. Existing measurements of this coefficient range over several orders of magnitude, so we used a recently developed microfluidic technique to measure it systematically in supported lipid membranes. Fluid shear stress was used to force the top leaflet of a supported membrane to slide over the stationary lower leaflet. Here, we show that this technique yields a reproducible measurement of the friction coefficient and is sensitive enough to detect differences in friction between membranes made from saturated and unsaturated lipids. Adding cholesterol to saturated and unsaturated membranes increased interleaflet friction significantly. We also discovered that fluid shear stress can reversibly induce gel phase in supported lipid bilayers that are close to the gel-transition temperature.
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10
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Barakat J, Squires TM. Curvature-Mediated Forces on Elastic Inclusions in Fluid Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:1099-1105. [PMID: 35015555 PMCID: PMC8793860 DOI: 10.1021/acs.langmuir.1c02709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/28/2021] [Indexed: 06/14/2023]
Abstract
Heterogeneous fluid interfaces often include two-dimensional solid domains that mechanically respond to changes in interfacial curvature. While this response is well-characterized for rigid inclusions, the influence of solid-like elasticity remains essentially unexplored. Here, we show that an initially flat, elastic inclusion embedded in a curved, fluid interface will exhibit qualitatively distinct behavior depending on its size and stiffness. Small, stiff inclusions are limited by bending and experience forces directed up gradients of Gaussian curvature, in keeping with prior findings for rigid discoids. By contrast, larger and softer inclusions are driven down gradients of squared Gaussian curvature in order to minimize the elastic penalty for stretching. Our calculations of the force on a solid inclusion are shown to collapse onto a universal curve spanning the bending- and stretching-limited regimes. From these results, we make predictions for the curvature-directed motion of deformable solids embedded within a model interface of variable Gaussian curvature.
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11
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Abstract
Hierarchic self-assembly underpins much of the form and function seen in synthetic or biological soft materials. Lipids are paramount examples, building themselves in nature or synthetically in a variety of meso/nanostructures. Synthetic block copolymers capture many of lipid's structural and functional properties. Lipids are typically biocompatible and high molecular weight polymers are mechanically robust and chemically versatile. The development of new materials for applications like controlled drug/gene/protein delivery, biosensors, and artificial cells often requires the combination of lipids and polymers. The emergent composite material, a "polymer-lipid hybrid membrane", displays synergistic properties not seen in pure components. Specific examples include the observation that hybrid membranes undergo lateral phase separation that can correlate in registry across multiple layers into a three-dimensional phase-separated system with enhanced permeability of encapsulated drugs. It is timely to underpin these emergent properties in several categories of hybrid systems ranging from colloidal suspensions to supported hybrid films. In this review, we discuss the form and function of a vast number of polymer-lipid hybrid systems published to date. We rationalize the results to raise new fundamental understanding of hybrid self-assembling soft materials as well as to enable the design of new supramolecular systems and applications.
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Affiliation(s)
- Yoo Kyung Go
- Department of Materials Science and Engineering, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
| | - Cecilia Leal
- Department of Materials Science and Engineering, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
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12
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Nesterov SV, Ilyinsky NS, Uversky VN. Liquid-liquid phase separation as a common organizing principle of intracellular space and biomembranes providing dynamic adaptive responses. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119102. [PMID: 34293345 DOI: 10.1016/j.bbamcr.2021.119102] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/13/2021] [Accepted: 07/18/2021] [Indexed: 02/07/2023]
Abstract
This work is devoted to the phenomenon of liquid-liquid phase separation (LLPS), which has come to be recognized as fundamental organizing principle of living cells. We distinguish separation processes with different dimensions. Well-known 3D-condensation occurs in aqueous solution and leads to membraneless organelle (MLOs) formation. 2D-films may be formed near membrane surfaces and lateral phase separation (membrane rafts) occurs within the membranes themselves. LLPS may also occur on 1D structures like DNA and the cyto- and nucleoskeleton. Phase separation provides efficient transport and sorting of proteins and metabolites, accelerates the assembly of metabolic and signaling complexes, and mediates stress responses. In this work, we propose a model in which the processes of polymerization (1D structures), phase separation in membranes (2D structures), and LLPS in the volume (3D structures) influence each other. Disordered proteins and whole condensates may provide membrane raft separation or polymerization of specific proteins. On the other hand, 1D and 2D structures with special composition or embedded IDRs can nucleate condensates. We hypothesized that environmental change may trigger a LLPS which can propagate within the cell interior moving along the cytoskeleton or as an autowave. New phase propagation quickly and using a low amount of energy adjusts cell signaling and metabolic systems to new demands. Cumulatively, the interconnected phase separation phenomena in different dimensions represent a previously unexplored system of intracellular communication and regulation which cannot be ignored when considering both physiological and pathological cell processes.
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Affiliation(s)
- Semen V Nesterov
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Institutskiy pereulok, 9, Dolgoprudny 141700, Russia; Kurchatov Complex of NBICS-Technologies, National Research Center Kurchatov Institute, Moscow 123182, Russia.
| | - Nikolay S Ilyinsky
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Institutskiy pereulok, 9, Dolgoprudny 141700, Russia
| | - Vladimir N Uversky
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Institutskiy pereulok, 9, Dolgoprudny 141700, Russia; Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., MDC07, Tampa, FL 33612, USA.
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13
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Visualizing the osmotic water permeability of a lipid bilayer under measured bilayer tension using a moving membrane method. J Memb Sci 2021. [DOI: 10.1016/j.memsci.2021.119231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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14
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Xin W, Wu H, Grason GM, Santore MM. Switchable positioning of plate-like inclusions in lipid membranes: Elastically mediated interactions of planar colloids in 2D fluids. SCIENCE ADVANCES 2021; 7:eabf1943. [PMID: 33811075 PMCID: PMC11057706 DOI: 10.1126/sciadv.abf1943] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
We demonstrate how manipulating curvature in an elastic fluid lamella enables the reversible relative positioning of flat, rigid, plate-like micrometer-scale inclusions, with spacings from about a micrometer to tens of micrometers. In an experimental model comprising giant unilamellar vesicles containing solid domain pairs coexisting in a fluid membrane, we adjusted vesicle inflation to manipulate membrane curvature and mapped the interdomain separation. A two-dimensional model of the pair potential predicts the salient experimental observations and reveals both attractions and repulsions, producing a potential minimum entirely a result of the solid domain rigidity and bending energy in the fluid membrane. The impact of vesicle inflation on domain separation in vesicles containing two solid domains was qualitatively consistent with observations in vesicles containing many domains. The behavior differs qualitatively from the pure repulsions between fluid membrane domains or interactions between nanoscopic inclusions whose repulsive or attractive character is not switchable.
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Affiliation(s)
- Weiyue Xin
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003, USA
| | - Hao Wu
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA
| | - Gregory M Grason
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA
| | - Maria M Santore
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA.
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15
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Páez-Pérez M, López-Duarte I, Vyšniauskas A, Brooks NJ, Kuimova MK. Imaging non-classical mechanical responses of lipid membranes using molecular rotors. Chem Sci 2020; 12:2604-2613. [PMID: 34164028 PMCID: PMC8179291 DOI: 10.1039/d0sc05874b] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 12/22/2020] [Indexed: 12/15/2022] Open
Abstract
Lipid packing in cellular membranes has a direct effect on membrane tension and microviscosity, and plays a central role in cellular adaptation, homeostasis and disease. According to conventional mechanical descriptions, viscosity and tension are directly interconnected, with increased tension leading to decreased membrane microviscosity. However, the intricate molecular interactions that combine to build the structure and function of a cell membrane suggest a more complex relationship between these parameters. In this work, a viscosity-sensitive fluorophore ('molecular rotor') is used to map changes in microviscosity in model membranes under conditions of osmotic stress. Our results suggest that the relationship between membrane tension and microviscosity is strongly influenced by the bilayer's lipid composition. In particular, we show that the effects of increasing tension are minimised for membranes that exhibit liquid disordered (Ld) - liquid ordered (Lo) phase coexistence; while, surprisingly, membranes in pure gel and Lo phases exhibit a negative compressibility behaviour, i.e. they soften upon compression.
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Affiliation(s)
- Miguel Páez-Pérez
- MSRH, Department of Chemistry, Imperial College London Wood Lane London W12 0BZ UK
| | - Ismael López-Duarte
- MSRH, Department of Chemistry, Imperial College London Wood Lane London W12 0BZ UK
- Departamento de Química Orgánica, Universidad Autónoma de Madrid Cantoblanco 28049 Madrid Spain
| | - Aurimas Vyšniauskas
- MSRH, Department of Chemistry, Imperial College London Wood Lane London W12 0BZ UK
- Center of Physical Sciences and Technology Saulėtekio av. 3 Vilnius Lithuania
| | - Nicholas J Brooks
- MSRH, Department of Chemistry, Imperial College London Wood Lane London W12 0BZ UK
| | - Marina K Kuimova
- MSRH, Department of Chemistry, Imperial College London Wood Lane London W12 0BZ UK
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16
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Lee HR, Lee Y, Oh SS, Choi SQ. Ultra-Stable Freestanding Lipid Membrane Array: Direct Visualization of Dynamic Membrane Remodeling with Cholesterol Transport and Enzymatic Reactions. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2002541. [PMID: 32924281 DOI: 10.1002/smll.202002541] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/09/2020] [Indexed: 06/11/2023]
Abstract
Cell membranes actively change their local compositions, serving essential biological processes such as cellular signaling and endocytosis. Although membrane dynamics is vital in the cellular functions, the complexity of natural membranes has made its fundamental understanding and systematic assessment difficult. Here, a powerful artificial membrane system is developed for real-time visualization of the spatiotemporal dynamics of membrane remodeling. Through well-defined air/oil/water interfaces on grid holes, tens of planar lipid bilayer membranes are easily created, and their reproducibility, controllability, and generality are highlighted. The freestanding membranes are large but also highly stable, facilitating direct long-term monitoring of dynamic membrane reconstitution caused by external stimuli. As an example to demonstrate the superiority of this membrane system, the effect of cholesterol trafficking, which significantly affects biophysical properties of cell membranes, is investigated at different membrane compositions. Cholesterol transport into and out of the membranes at different rates causes anomalous lipid arrangements through cholesterol-mediated phase transitions and decomposition, which have never been witnessed before. Furthermore, enzyme-induced membrane dynamics is successfully shown in this platform; sphingomyelinases locally generate asymmetry between two membrane leaflets. This technique is broadly applicable for exploring the membrane heterogeneity under various membrane-based reactions, providing valuable insight into the membrane dynamics.
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Affiliation(s)
- Hyun-Ro Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Yohan Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Seung Soo Oh
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Siyoung Q Choi
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
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17
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Omar YAD, Sahu A, Sauer RA, Mandadapu KK. Nonaxisymmetric Shapes of Biological Membranes from Locally Induced Curvature. Biophys J 2020; 119:1065-1077. [PMID: 32860742 DOI: 10.1016/j.bpj.2020.07.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 07/07/2020] [Accepted: 07/15/2020] [Indexed: 01/24/2023] Open
Abstract
In various biological processes such as endocytosis and caveolae formation, the cell membrane is locally deformed into curved morphologies. Previous models to study membrane morphologies resulting from locally induced curvature often only consider the possibility of axisymmetric shapes-an indeed unphysical constraint. Past studies predict that the cell membrane buds at low resting tensions and stalls at a flat pit at high resting tensions. In this work, we lift the restriction to axisymmetry to study all possible membrane morphologies. Only if the resting tension of the membrane is low, we reproduce axisymmetric membrane morphologies. When the resting tension is moderate to high, we show that 1) axisymmetric membrane pits are unstable and 2) nonaxisymmetric ridge-shaped structures are energetically favorable. Furthermore, we find the interplay between intramembrane viscous flow and the rate of induced curvature affects the membrane's ability to transition into nonaxisymmetric ridges and axisymmetric buds. In particular, we show that axisymmetric buds are favored when the induced curvature is rapidly increased, whereas nonaxisymmetric ridges are favored when the curvature is slowly increased. Our results hold relevant implications for biological processes such as endocytosis and physical phenomena like phase separation in lipid bilayers.
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Affiliation(s)
- Yannick A D Omar
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California.
| | - Amaresh Sahu
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California.
| | - Roger A Sauer
- Aachen Institute for Advanced Study in Computational Engineering Science, RWTH Aachen University, Aachen, Germany.
| | - Kranthi K Mandadapu
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California.
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18
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Kumar D, Richter CM, Schroeder CM. Double-mode relaxation of highly deformed anisotropic vesicles. Phys Rev E 2020; 102:010605. [PMID: 32794982 DOI: 10.1103/physreve.102.010605] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/17/2020] [Indexed: 06/11/2023]
Abstract
Lipid vesicles are known to undergo complex conformational transitions, but it remains challenging to systematically characterize nonequilibrium membrane dynamics in flow. Here, we report the direct observation of anisotropic vesicle relaxation from highly deformed shapes using a Stokes trap. Vesicle shape relaxation is described by two distinct characteristic timescales governed by the bending modulus and membrane tension. Interestingly, the fast double-mode timescale is found to depend on vesicle deflation or reduced volume. Experimental results are well described by a viscoelastic model of a deformed membrane. Overall, these results show that vesicle relaxation is governed by an interplay between membrane elastic moduli, surface tension, and vesicle deflation.
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Affiliation(s)
- Dinesh Kumar
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Channing M Richter
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Charles M Schroeder
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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19
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Zhang B, Zhou X, Miao Y, Wang X, Yang Y, Zhang X, Gan Y. Effect of phosphatidylcholine on the stability and lipolysis of nanoemulsion drug delivery systems. Int J Pharm 2020; 583:119354. [PMID: 32348799 DOI: 10.1016/j.ijpharm.2020.119354] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/30/2020] [Accepted: 04/18/2020] [Indexed: 12/17/2022]
Abstract
Phosphatidylcholines (PCs) have been widely used in pharmaceutical research. Unfortunately, our understanding of how PCs influence the in vivo lipolysis process of drug delivery systems is still limited. In this study, PCs with fatty acid chains of varying lengths and saturability were used as emulsifiers to prepare curcumin-loaded nanoemulsions (Cur-NEs). The differences in particle size as well as drug and free fatty acid release during the lipolysis process were studied in a simulated blood environment. Furthermore, the pharmacokinetics and antitumor efficacy of Cur-NEs were evaluated in mice. The prepared 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-stabilized Cur-NEs showed similar particle size and stability during storage but exhibited different lipolysis behaviors in vitro and in vivo. Due to the gel state of DPPC in the physiological environment, DPPC-stabilized Cur-NEs had low binding affinity with proteins and maintained their integrity in plasma, leading to sustained drug release, prolonged circulation time and enhanced antitumor efficacy in 4T1 tumor-bearing mice. In contrast, DOPC and DSPC-stabilized Cur-NEs were prone to coalescence in the plasma, resulting in rapid drug release and elimination from circulation. Our findings demonstrated that proper use of PCs is beneficial for obtaining desired transport behavior and drug therapeutic effects, providing guiding principles for rational design of nanodelivery systems.
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Affiliation(s)
- Bo Zhang
- Nano Science and Technology Institute, University of Science and Technology of China, Suzhou 215123, China; Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Xin Zhou
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; Department of Pharmacy, Nanchang University, Nanchang 330031, China
| | - Yunqiu Miao
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Xiaoli Wang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Yuting Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; Department of Pharmacy, Nanchang University, Nanchang 330031, China
| | - Xinxin Zhang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
| | - Yong Gan
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
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20
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Gu RX, Baoukina S, Tieleman DP. Phase Separation in Atomistic Simulations of Model Membranes. J Am Chem Soc 2020; 142:2844-2856. [DOI: 10.1021/jacs.9b11057] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Ruo-Xu Gu
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - Svetlana Baoukina
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - D. Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
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21
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Appadurai D, Gay L, Moharir A, Lang MJ, Duncan MC, Schmidt O, Teis D, Vu TN, Silva M, Jorgensen EM, Babst M. Plasma membrane tension regulates eisosome structure and function. Mol Biol Cell 2019; 31:287-303. [PMID: 31851579 PMCID: PMC7183764 DOI: 10.1091/mbc.e19-04-0218] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Eisosomes are membrane furrows at the cell surface of yeast that have been shown to function in two seemingly distinct pathways, membrane stress response and regulation of nutrient transporters. We found that many stress conditions affect both of these pathways by changing plasma membrane tension and thus the morphology and composition of eisosomes. For example, alkaline stress causes swelling of the cell and an endocytic response, which together increase membrane tension, thereby flattening the eisosomes. The flattened eisosomes affect membrane stress pathways and release nutrient transporters, which aids in their down-regulation. In contrast, glucose starvation or hyperosmotic shock causes cell shrinking, which results in membrane slack and the deepening of eisosomes. Deepened eisosomes are able to trap nutrient transporters and protect them from rapid endocytosis. Therefore, eisosomes seem to coordinate the regulation of both membrane tension and nutrient transporter stability.
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Affiliation(s)
- Daniel Appadurai
- Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112
| | - Lincoln Gay
- Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112
| | - Akshay Moharir
- Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112
| | - Michael J Lang
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Mara C Duncan
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Oliver Schmidt
- Division of Cell Biology, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - David Teis
- Division of Cell Biology, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Thien N Vu
- School of Biological Sciences, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112
| | - Malan Silva
- School of Biological Sciences, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112
| | - Erik M Jorgensen
- School of Biological Sciences, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112
| | - Markus Babst
- Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112
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22
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Li S, Zandi R, Travesset A, Grason GM. Ground States of Crystalline Caps: Generalized Jellium on Curved Space. PHYSICAL REVIEW LETTERS 2019; 123:145501. [PMID: 31702180 DOI: 10.1103/physrevlett.123.145501] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Indexed: 06/10/2023]
Abstract
We study the ground states of crystals on spherical surfaces. These ground states consist of positive disclination defects in structures spanning from flat and weakly curved caps to closed shells. Comparing two continuum theories and one discrete-lattice simulation, we first investigate the transition between defect-free caps to single-disclination ground states and show it to be continuous and symmetry breaking. Further, we show that ground states adopt icosahedral subgroup symmetries across the full range of curvatures, even far from the closure of complete shells. While superficially similar to other models of 2D "jellium" (e.g., superconducting disks and 2D Wigner crystals), the interplay between the free edge of caps and the non-Euclidean geometry of its embedding leads to nontrivial ground state behavior that is without counterpart in planar jellium models.
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Affiliation(s)
- Siyu Li
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Roya Zandi
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Alex Travesset
- Department of Physics and Astronomy, Iowa State University and Ames Lab, Ames, Iowa 50011, USA
| | - Gregory M Grason
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
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23
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Engberg O, Scheidt HA, Nyholm TKM, Slotte JP, Huster D. Membrane Localization and Lipid Interactions of Common Lipid-Conjugated Fluorescence Probes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:11902-11911. [PMID: 31424941 DOI: 10.1021/acs.langmuir.9b01202] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lateral segregation of lipids in model and biological membranes has been studied intensively in the last decades using a comprehensive set of experimental techniques. Most methods require a probe to report on the biophysical properties of a specific molecule in the lipid bilayer. Because such probes can adversely affect the results of the measurement and perturb the local membrane structure and dynamics, a detailed understanding of probe behavior and its influence on the properties of its direct environment is important. Membrane phase-selective and lipid-mimicking molecules represent common types of probes. Here, we have studied how the fluorescent probes trans-parinaric acid (tPA), diphenylhexatriene (DPH), and 1-oleoyl-2-propionyl[DPH]-sn-glycero-3-phosphocholine (O-DPH-PC) affect the membrane properties of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) bilayers using 2H and 31P NMR spectroscopy in the solid state. In addition, using 2D 1H magic-angle spinning (MAS) nuclear Overhauser enhancement spectroscopy (NOESY) NMR, we have determined the distribution of the probe moieties in the POPC membrane parallel to the membrane normal. We found that the different probes exhibit distinct membrane localizations and distributions, e.g. tPA is located parallel to the membrane normal while DPH predominantly exist in two orientations. Further, tPA was conjugated to sphingomyelin (tPA-SM) as a substitute for the acyl chain in the SM. 1H NOESY NMR was used to probe the interaction of the tPA-SM with cholesterol as dominant in liquid ordered membrane domains in comparison to POPC-cholesterol interaction in membranes composed of ternary lipid mixtures. We could show that tPA-SM exhibited a strong favorable and very temperature-dependent interaction with cholesterol in comparison to POPC. In conclusion, the NMR techniques can explain probe behavior but also be used to measure lipid-specific affinities between different lipid segments and individual molecules in complex bilayers, relevant to understanding nanodomain formation in biological membranes.
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Affiliation(s)
- Oskar Engberg
- Institute for Medical Physics and Biophysics, Medical Department , Leipzig University , Leipzig , Germany
- Biochemistry, Faculty of Science and Engineering , Åbo Akademi University , Turku , Finland
| | - Holger A Scheidt
- Institute for Medical Physics and Biophysics, Medical Department , Leipzig University , Leipzig , Germany
| | - Thomas K M Nyholm
- Biochemistry, Faculty of Science and Engineering , Åbo Akademi University , Turku , Finland
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering , Åbo Akademi University , Turku , Finland
| | - Daniel Huster
- Institute for Medical Physics and Biophysics, Medical Department , Leipzig University , Leipzig , Germany
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24
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Loh J, Chuang MC, Lin SS, Joseph J, Su YA, Hsieh TL, Chang YC, Liu AP, Liu YW. An acute decrease in plasma membrane tension induces macropinocytosis via PLD2 activation. J Cell Sci 2019; 132:jcs.232579. [PMID: 31391241 DOI: 10.1242/jcs.232579] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 07/29/2019] [Indexed: 12/13/2022] Open
Abstract
Internalization of macromolecules and membrane into cells through endocytosis is critical for cellular growth, signaling and plasma membrane (PM) tension homeostasis. Although endocytosis is responsive to both biochemical and physical stimuli, how physical cues modulate endocytic pathways is less understood. Contrary to the accumulating discoveries on the effects of increased PM tension on endocytosis, less is known about how a decrease of PM tension impacts on membrane trafficking. Here, we reveal that an acute decrease of PM tension results in phosphatidic acid (PA) production, F-actin and phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2]-enriched dorsal membrane ruffling and subsequent macropinocytosis in myoblasts. The PA production induced by decreased PM tension depends on phospholipase D2 (PLD2) activation via PLD2 nanodomain disintegration. Furthermore, the 'decreased PM tension-PLD2-macropinocytosis' pathway is prominent in myotubes, reflecting a potential mechanism of PM tension homeostasis upon intensive muscle stretching and relaxation. Together, we identify a new mechanotransduction pathway that converts an acute decrease in PM tension into PA production and then initiates macropinocytosis via actin and PI(4,5)P2-mediated processes.
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Affiliation(s)
- Julie Loh
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Mei-Chun Chuang
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Shan-Shan Lin
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Jophin Joseph
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - You-An Su
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Tsung-Lin Hsieh
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Yu-Chen Chang
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ya-Wen Liu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan .,Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
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25
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Morandi MI, Sommer M, Kluzek M, Thalmann F, Schroder AP, Marques CM. DPPC Bilayers in Solutions of High Sucrose Content. Biophys J 2019; 114:2165-2173. [PMID: 29742409 DOI: 10.1016/j.bpj.2018.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 03/21/2018] [Accepted: 04/02/2018] [Indexed: 10/17/2022] Open
Abstract
The properties of lipid bilayers in sucrose solutions have been intensely scrutinized over recent decades because of the importance of sugars in the field of biopreservation. However, a consensus has not yet been formed on the mechanisms of sugar-lipid interaction. Here, we present a study on the effect of sucrose on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine bilayers that combines calorimetry, spectral fluorimetry, and optical microscopy. Intriguingly, our results show a significant decrease in the transition enthalpy but only a minor shift in the transition temperature. Our observations can be quantitatively accounted for by a thermodynamic model that assumes partial delayed melting induced by sucrose adsorption at the membrane interface.
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Affiliation(s)
- Mattia I Morandi
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France
| | - Mathieu Sommer
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France
| | - Monika Kluzek
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France
| | - Fabrice Thalmann
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France
| | - André P Schroder
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France
| | - Carlos M Marques
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France.
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26
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Neuronal stretch reception – Making sense of the mechanosense. Exp Cell Res 2019; 378:104-112. [DOI: 10.1016/j.yexcr.2019.01.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 01/14/2019] [Accepted: 01/17/2019] [Indexed: 02/06/2023]
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27
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Pinto OA, Disalvo EA. A new model for lipid monolayer and bilayers based on thermodynamics of irreversible processes. PLoS One 2019; 14:e0212269. [PMID: 30947264 PMCID: PMC6448890 DOI: 10.1371/journal.pone.0212269] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 01/30/2019] [Indexed: 11/29/2022] Open
Abstract
Lipid monolayers are used as experimental model systems to study the physical chemical properties of biomembranes. With this purpose, surface pressure/area per molecule isotherms provide a way to obtain information on packing and compressibility properties of the lipids. These isotherms have been interpreted considering the monolayer as a two dimensional ideal or van der Waals gas without contact with the water phase. These modelistic approaches do not fit the experimental results. Based on Thermodynamics of Irreversible Processes (TIP), the expansion/compression process is interpreted in terms of coupled phenomena between area changes and water fluxes between a bidimensional solution of hydrated head groups in the monolayer and the bulk solution. The formalism obtained can reproduce satisfactorily the surface pressure/area per lipid isotherms of monolayer in different states and also can explain the area expansion and compression produced in particles enclosed by bilayers during osmotic fluxes. This novel approach gives relevance to the lipid-water interaction in restricted media near the membrane and provides a formalism to understand the thermodynamic and kinetic response of biointerphases to biological effectors.
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Affiliation(s)
- O. A. Pinto
- Instituto de Bionanotecnología del NOA (INBIONATEC), Universidad Nacional de Santiago de Estero (UNSE- CONICET), Villa el Zanjón, Santiago del Estero, Argentina
| | - E. A. Disalvo
- Laboratorio de Biointerfases y Sistemas Biomiméticos, Centro de Investigaciones en Biofisica Aplicada y Alimentos (CIBAAL) (UNSE-CONICET), Villa el Zanjón, Santiago del Estero, Argentina
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28
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Balleza D, Mescola A, Marín-Medina N, Ragazzini G, Pieruccini M, Facci P, Alessandrini A. Complex Phase Behavior of GUVs Containing Different Sphingomyelins. Biophys J 2019; 116:503-517. [PMID: 30665697 DOI: 10.1016/j.bpj.2018.12.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 11/28/2018] [Accepted: 12/20/2018] [Indexed: 01/06/2023] Open
Abstract
Understanding the lateral organization of biological membranes plays a key role on the road to fully appreciate the physiological functions of this fundamental barrier between the inside and outside regions of a cell. Ternary lipid bilayers composed of a high and a low melting temperature lipid and cholesterol represent a model system that mimics some of the important thermodynamical features of much more complex lipid mixtures such as those found in mammal membranes. The phase diagram of these ternary mixtures can be studied exploiting fluorescence microscopy in giant unilamellar vesicles, and it is typically expected to give rise, for specific combinations of composition and temperature, to regions of two-phase coexistence and a region with three-phase coexistence, namely, the liquid-ordered, liquid-disordered, and solid phases. Whereas the observation of two-phase coexistence is routinely possible using fluorescence microscopy, the three-phase region is more elusive to study. In this article, we show that particular lipid mixtures containing diphytanoyl-phosphatidylcholine and cholesterol plus different types of sphingomyelin (SM) are prone to produce bilayer regions with more than two levels of fluorescence intensity. We found that these intensity levels occur at low temperature and are linked to the copresence of long and asymmetric chains in SMs and diphytanoyl-phosphatidylcholine in the lipid mixtures. We discuss the possible interpretations for this observation in terms of bilayer phase organization in the presence of sphingolipids. Additionally, we also show that in some cases, liposomes in the three-phase coexistence state exhibit extreme sensitivity to lateral tension. We hypothesize that the appearance of the different phases is related to the asymmetric structure of SMs and to interdigitation effects.
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Affiliation(s)
| | | | | | - Gregorio Ragazzini
- Istituto Nanoscienze CNR, S3, Modena, Italy; Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Università di Modena e Reggio Emilia, Modena, Italy
| | | | | | - Andrea Alessandrini
- Istituto Nanoscienze CNR, S3, Modena, Italy; Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Università di Modena e Reggio Emilia, Modena, Italy.
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29
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Knorr RL, Steinkühler J, Dimova R. Micron-sized domains in quasi single-component giant vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1957-1964. [DOI: 10.1016/j.bbamem.2018.06.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 06/25/2018] [Accepted: 06/26/2018] [Indexed: 12/29/2022]
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30
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Miyake M, Kakizawa Y, Tobori N, Kurioka M, Tabuchi N, Kon R, Shimokawa N, Tsujino Y, Takagi M. Membrane permeation of giant unilamellar vesicles and corneal epithelial cells with lipophilic vitamin nanoemulsions. Colloids Surf B Biointerfaces 2018; 169:444-452. [DOI: 10.1016/j.colsurfb.2018.05.052] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 05/08/2018] [Accepted: 05/23/2018] [Indexed: 01/09/2023]
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31
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Boyd MA, Kamat NP. Visualizing Tension and Growth in Model Membranes Using Optical Dyes. Biophys J 2018; 115:1307-1315. [PMID: 30219285 DOI: 10.1016/j.bpj.2018.08.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 08/16/2018] [Accepted: 08/20/2018] [Indexed: 11/16/2022] Open
Abstract
Cells dynamically regulate their membrane surface area during a variety of processes critical to their survival. Recent studies with model membranes have pointed to a general mechanism for surface area regulation under tension in which cell membranes unfold or take up lipid to accommodate membrane strain. Yet we lack robust methods to simultaneously measure membrane tension and surface area changes in real time. Using lipid vesicles that contain two dyes isolated to spatially distinct parts of the membrane, we introduce, to our knowledge, a new method to monitor the processes of membrane stretching and lipid uptake in model membranes. Laurdan, located within the bilayer membrane, and Förster resonance energy transfer dyes, localized to the membrane exterior, act in concert to report changes in membrane tension and lipid uptake during osmotic stress. We use these dyes to show that membranes under tension take up lipid more quickly and in greater amounts compared to their nontensed counterparts. Finally, we show that this technique is compatible with microscopy, enabling real-time analysis of membrane dynamics on a single vesicle level. Ultimately, the combinatorial use of these probes offers a more complete picture of changing membrane morphology. Our optical method allows us to remotely track changes in membrane tension and surface area with model membranes, offering new opportunities to track morphological changes in artificial and biological membranes and providing new opportunities in fields ranging from mechanobiology to drug delivery.
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Affiliation(s)
- Margrethe A Boyd
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois
| | - Neha P Kamat
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois; Center for Synthetic Biology, Northwestern University, Evanston, Illinois; Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois.
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32
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Beltramo PJ, Scheidegger L, Vermant J. Toward Realistic Large-Area Cell Membrane Mimics: Excluding Oil, Controlling Composition, and Including Ion Channels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:5880-5888. [PMID: 29715042 DOI: 10.1021/acs.langmuir.8b00837] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Capacitance measurements provide unique insights into the thickness, compressibility, and composition of large-area membrane bilayers and are used here in addition to demonstrate the successful incorporation of model ion channels. The simultaneous ability to control the bilayer size, manipulate tension, and optically monitor and electrically stimulate freestanding membranes enables precise determination of their specific capacitance and thickness across a wide range of areas. We confirm that membranes formed by this recently developed technique have capacitive properties similar to those formed by existing protocols, including solvent-free approaches, and discuss the effect using either hexadecane or squalene as the oil solvent. The results obtained here are relevant for other methods where lipid membranes are reconstituted from a bulk oil solvent. Because biological membranes have a diverse phospholipid profile, we show that the technique can successfully reconstitute membranes with binary composition mixtures. As an outlook, we show the capability of model membrane proteins, specifically α-hemolysin and alamethicin, to be incorporated into the formed bilayers and measure ion transport.
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Affiliation(s)
- Peter J Beltramo
- Department of Chemical Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States
| | - Laura Scheidegger
- Department of Materials , ETH Zürich , Vladimir-Prelog-Weg 5 , 8093 Zürich , Switzerland
| | - Jan Vermant
- Department of Materials , ETH Zürich , Vladimir-Prelog-Weg 5 , 8093 Zürich , Switzerland
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33
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The role of gel-phase domains in electroporation of vesicles. Sci Rep 2018; 8:4758. [PMID: 29555940 PMCID: PMC5859178 DOI: 10.1038/s41598-018-23097-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 03/06/2018] [Indexed: 12/18/2022] Open
Abstract
Transient permeabilisation of the cell membrane is a critical step to introduce drugs or DNA into living cells, yet challenging for both biological research and therapeutic applications. To achieve this, electroporation (or electropermeabilisation) has become a widely used method due to its simplicity to deliver almost any biomolecule to any cell type. Although this method demonstrates promise in the field of drug/gene delivery, the underlying physical mechanisms of the response of the heterogeneous cell membrane to strong electric pulses is still unknown. In this study, we have investigated the role of gel-phase lipids in the electroporation of binary giant unilamellar vesicles (GUVs), composed from DPPC (gel-phase) and DPhPC (fluid-phase) lipids (molar ratio 8:2 and 2:8). We have observed that the exposure to electric pulses leads to expel of fluid-phase lipids and concomitant decrease in GUV size, whereas the gel-phase domains become buckled. Based on experiments on pure fluid-phase and gel-phase GUVs, we have found that fluid-phase lipids can be expelled by electrical forces and the highly viscous gel-phase lipids cannot. Moreover, our analyses suggest that pore formation occurs primarily in fluid-phase domains and that the pore size is similar in all GUVs containing fluid-phase lipids, irrespective of the gel-phase percentage.
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34
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Zhang H, Dudley EG, Davidson PM, Harte F. Critical Concentration of Lecithin Enhances the Antimicrobial Activity of Eugenol against Escherichia coli. Appl Environ Microbiol 2017; 83:e03467-16. [PMID: 28213539 PMCID: PMC5377508 DOI: 10.1128/aem.03467-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 01/26/2017] [Indexed: 11/20/2022] Open
Abstract
Lecithin is a natural emulsifier used in a wide range of food and nonfood applications to improve physical stability, with no known bioactive effects. In this study, the effect of lecithin on the antimicrobial performance of a constant eugenol concentration was tested against three Escherichia coli strains (C600, 0.1229, and O157:H7 strain ATCC 700728). This is the first study, to our knowledge, focusing on lecithin at concentrations below those commonly used in foods to improve the stability of oil in water emulsions (≤10 mg/100 ml). For all three cultures, significant synergistic antimicrobial effects were observed when E. coli cultures were exposed to a constant eugenol concentration (ranging from 0.043 to 0.050% [wt/wt]) together with critical lecithin concentrations ranging from 0.5 to 1 mg/100 ml. Increasing the concentration of lecithin above 1 mg/100 ml (up to 10 mg/100 ml lecithin) diminished the antibacterial effect to values similar to those with eugenol-only treatments. The formation of aggregates (<100 nm) at the critical lecithin concentration was observed using cryo-transmission electron microscopy (cryo-TEM), together with a reduction in light absorbance at 284 nm. At critically low concentrations of lecithin, the formation of nanoscale aggregates is responsible for improving eugenol antimicrobial effects.IMPORTANCE Essential oils (EOs) are effective natural antimicrobials. However, their hydrophobicity and strong aromatic character limit the use of essential oils in food systems. Emulsifiers (e.g., lecithin) increase the stability of EOs in water-based systems but fail to consistently improve antimicrobial effects. We demonstrate that lecithin, within a narrow critical concentration window, can enhance the antimicrobial properties of eugenol. This study highlights the potential bioactivity of lecithin when utilized to effectively control foodborne pathogens.
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Affiliation(s)
- Haoshu Zhang
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Edward G Dudley
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA
- Center for Molecular Immunology and Infectious Disease, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - P Michael Davidson
- Department of Food Science and Technology, University of Tennessee, Knoxville, Tennessee, USA
| | - Federico Harte
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA
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35
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Hasan IY, Mechler A. Nanoviscosity Measurements Revealing Domain Formation in Biomimetic Membranes. Anal Chem 2017; 89:1855-1862. [PMID: 28208292 DOI: 10.1021/acs.analchem.6b04256] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Partitioning of lipid molecules in biomimetic membranes is a model system for the study of naturally occurring domains, such as rafts, in biological membranes. The existence of nanometer scale membrane domains in binary lipid mixtures has been shown with microscopy methods; however, the nature of these domains has not been established unequivocally. A common notion is to ascribe domain separation to thermodynamic phase equilibria. However, characterizing thermodynamic phases of single bilayer membranes has not been possible due to their extreme dimensions: the size of the domains falls to the order of tens to hundreds of nanometers whereas the membrane thickness is only a few nanometers. Here, we present direct measurements of phase transitions in single bilayers of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) phospholipid mixtures using quartz crystal microbalance-based nanoviscosity measurements. Coexisting thermodynamic phases have been successfully identified, and a phase diagram was constructed for the single bilayer binary lipid system. It was demonstrated that domain separation only takes place in planar membranes, and thus, it is absent in liposomes and not detectable in calorimetric measurements on liposome suspensions. On the basis of energetic analysis, the main transition was identified as the breaking of van der Waals interactions between the acyl chains.
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Affiliation(s)
- Imad Younus Hasan
- La Trobe Institute for Molecular Science, La Trobe University , Melbourne, Victoria 3086, Australia
| | - Adam Mechler
- La Trobe Institute for Molecular Science, La Trobe University , Melbourne, Victoria 3086, Australia
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36
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Dao TPT, Fernandes F, Ibarboure E, Ferji K, Prieto M, Sandre O, Le Meins JF. Modulation of phase separation at the micron scale and nanoscale in giant polymer/lipid hybrid unilamellar vesicles (GHUVs). SOFT MATTER 2017; 13:627-637. [PMID: 27991638 DOI: 10.1039/c6sm01625a] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Phase separation in giant polymer/lipid hybrid unilamellar vesicles (GHUVs) has been described over the last few years. However there is still a lack of understanding on the physical and molecular factors governing the phase separation in such systems. Among these parameters it has been suggested that in analogy to multicomponent lipid vesicles hydrophobic mismatches as well as lipid fluidity play a role. In this work, we aim to map a global picture of phase separation and domain formation in the membrane of GHUVs by using various copolymers based on poly(dimethylsiloxane) (PDMS) and poly(ethylene glycol) (PEO) with different architectures (grafted, triblock) and molar masses, combined with phospholipids in the fluid (POPC) or gel state (DPPC) at room temperature. From confocal imaging and fluorescence lifetime imaging microscopy (FLIM) techniques, the phase separation into either micro- or nano-domains within GHUVs was studied. In particular, our systematic studies demonstrate that in addition to the lipid/polymer fraction or the lipid physical state, important factors such as line tension at lipid polymer/lipid boundaries can be finely modulated by the molar mass and the architecture of the copolymer and lead to the formation of stable lipid domains with different sizes and morphologies in such GHUVs.
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Affiliation(s)
- Thi Phuong Tuyen Dao
- University of Bordeaux, LCPO UMR 5629, 16 avenue PeyBerland, F-33600 Pessac, France. and CNRS, Laboratoire de Chimie des Polymères Organiques, UMR 5629, F-33600, Pessac, France and Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Universidade de Lisboa Instituto Superior Técnico, 1049-001 Lisboa, Portugal.
| | - Fabio Fernandes
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Universidade de Lisboa Instituto Superior Técnico, 1049-001 Lisboa, Portugal. and UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 32829-516, Caparica, Lisbon, Portugal
| | - Emmanuel Ibarboure
- University of Bordeaux, LCPO UMR 5629, 16 avenue PeyBerland, F-33600 Pessac, France. and CNRS, Laboratoire de Chimie des Polymères Organiques, UMR 5629, F-33600, Pessac, France
| | - Khalid Ferji
- University of Bordeaux, LCPO UMR 5629, 16 avenue PeyBerland, F-33600 Pessac, France. and CNRS, Laboratoire de Chimie des Polymères Organiques, UMR 5629, F-33600, Pessac, France
| | - Manuel Prieto
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Universidade de Lisboa Instituto Superior Técnico, 1049-001 Lisboa, Portugal.
| | - Olivier Sandre
- University of Bordeaux, LCPO UMR 5629, 16 avenue PeyBerland, F-33600 Pessac, France. and CNRS, Laboratoire de Chimie des Polymères Organiques, UMR 5629, F-33600, Pessac, France
| | - Jean-François Le Meins
- University of Bordeaux, LCPO UMR 5629, 16 avenue PeyBerland, F-33600 Pessac, France. and CNRS, Laboratoire de Chimie des Polymères Organiques, UMR 5629, F-33600, Pessac, France
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37
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Abstract
Domain migration is observed on the surface of ternary giant unilamellar vesicles held in a temperature gradient in conditions where they exhibit coexistence of two liquid phases. The migration localizes domains to the hot side of the vesicle, regardless of whether the domain is composed of the more ordered or disordered phase and regardless of the proximity to chamber boundaries. The distribution of domains is explored for domains that coarsen and for those held apart due to long-range repulsions. After considering several potential mechanisms for the migration, including the temperature preferences for each lipid, the favored curvature for each phase, and the thermophoretic flow around the vesicle, we show that observations are consistent with the general process of minimizing the system's line tension energy, because of the lowering of line interface energy closer to mixing. DNA strands, attached to the lipid bilayer with cholesterol anchors, act as an exemplar "cargo," demonstrating that the directed motion of domains toward higher temperatures provides a route to relocate species that preferentially reside in the domains.
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38
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Hasan IY, Mechler A. Analytical approaches to study domain formation in biomimetic membranes. Analyst 2017; 142:3062-3078. [PMID: 28758651 DOI: 10.1039/c7an01038a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Novel characterization methods open new horizons in the study of membrane mixtures.
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Affiliation(s)
- Imad Younus Hasan
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
| | - Adam Mechler
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
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39
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Shigyou K, Nagai KH, Hamada T. Lateral Diffusion of a Submicrometer Particle on a Lipid Bilayer Membrane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:13771-13777. [PMID: 27779878 DOI: 10.1021/acs.langmuir.6b02448] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In past decades, nanoparticles and nanomaterials have been actively used for applications such as visualizing nano/submicrometer cell structure, killing cancer cells, and using drug delivery systems. It is important to understand the physicochemical mechanisms that govern the motion of nanoparticles on a plasma membrane surface. However, the motion of small particles of <1000 nm on lipid membranes is poorly understood. In this study, we investigated the diffusion of particles with a diameter of 200-800 nm on a lipid membrane using cell-sized liposomes. Particle-associated liposomes were obtained by applying centrifugal force to a mixture of liposomes and particle solutions. We measured the thermal motion of the particles by phase-contrast microscopy. We found that (i) the particle-size dependence of the diffusion of particles adhering to membranes was better described by the DADL model rather than the Einstein-Stokes model, (ii) the diffusion coefficient of a particle strongly depends on the adsorption state of the particle, such as fully or partially wrapped by the membrane, and (iii) anomalous diffusion was induced by the localization of particles on the neck of budded vesicles.
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Affiliation(s)
- Kazuki Shigyou
- Japan Advanced Institute of Science and Technology, School of Materials Science , 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Ken H Nagai
- Japan Advanced Institute of Science and Technology, School of Materials Science , 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Tsutomu Hamada
- Japan Advanced Institute of Science and Technology, School of Materials Science , 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
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40
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Affiliation(s)
- Gregory M. Grason
- Department of Polymer Science, University of Massachusetts, Amherst, Massachusetts 01003, USA
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41
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Shimokawa N, Himeno H, Hamada T, Takagi M, Komura S, Andelman D. Phase Diagrams and Ordering in Charged Membranes: Binary Mixtures of Charged and Neutral Lipids. J Phys Chem B 2016; 120:6358-67. [DOI: 10.1021/acs.jpcb.6b03102] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Naofumi Shimokawa
- School
of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Hiroki Himeno
- Health
Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Kagawa 761-0395, Japan
| | - Tsutomu Hamada
- School
of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Masahiro Takagi
- School
of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Shigeyuki Komura
- Department
of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - David Andelman
- School
of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact
Sciences, Tel Aviv University, Ramat Aviv 69978, Tel Aviv, Israel
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42
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Zhu T, Jiang Z, Ma Y, Hu Y. Preservation of Supported Lipid Membrane Integrity from Thermal Disruption: Osmotic Effect. ACS APPLIED MATERIALS & INTERFACES 2016; 8:5857-5866. [PMID: 26886864 DOI: 10.1021/acsami.5b12153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Preservation of structural integrity under various environmental conditions is one major concern in the development of the supported lipid membrane (SLM)-based devices. It is common for SLMs to experience temperature shifts from manufacture, processing, storage, and transport to operation. In this work, we studied the thermal adaption of the supported membranes on silica substrates. Homogenous SLMs with little defects were formed through the vesicle fusion method. The mass and fluidity of the bilayers were found to deteriorate from a heating process but not a cooling process. Fluorescence characterizations showed that the membranes initially budded as a result of heating-induced lipid lateral area expansion, followed by the possible fates including maintenance, retraction, and fission, among which the last contributes to the irreversible compromise of the SLM integrity and spontaneous release of the interlipid stress accumulated. Based on the mechanism, we developed a strategy to protect SLMs from thermal disruption by increasing the solute concentration in medium. An improved preservation of the membrane mass and fluidity against the heating process was observed, accompanied by a decrease in the retraction and fission of the buds. Theoretical analysis revealed a high osmotic energy penalty for the fission, which accounts for the depressed disruption. This osmotic-based protection strategy is facile, solute nonspecific, and long-term efficient and has little impact on the original SLM properties. The results may help broaden SLM applications and sustain the robustness of SLM-based devices under multiple thermal conditions.
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Affiliation(s)
- Tao Zhu
- Collaborative Innovation Center of Advanced Microstructures and Department of Physics, Nanjing University , Nanjing 210093, China
| | - Zhongying Jiang
- School of Electronics and Information Engineering, Yi Li Normal University , Yining 835000, China
- Laboratory of Solid State Microstructures, Nanjing University , Nanjing 210093, China
| | - Yuqiang Ma
- Collaborative Innovation Center of Advanced Microstructures and Department of Physics, Nanjing University , Nanjing 210093, China
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University , Suzhou 215006, China
| | - Yong Hu
- College of Engineering and Applied Sciences, Nanjing University , Nanjing 210093, China
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43
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Ho JCS, Rangamani P, Liedberg B, Parikh AN. Mixing Water, Transducing Energy, and Shaping Membranes: Autonomously Self-Regulating Giant Vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:2151-63. [PMID: 26866787 DOI: 10.1021/acs.langmuir.5b04470] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Giant lipid vesicles are topologically closed compartments bounded by semipermeable flexible shells, which isolate femto- to picoliter quantities of the aqueous core from the surrounding bulk. Although water equilibrates readily across vesicular walls (10(-2)-10(-3) cm(3) cm(-2) s(-1)), the passive permeation of solutes is strongly hindered. Furthermore, because of their large volume compressibility (∼10(9)-10(10) N m(-2)) and area expansion (10(2)-10(3) mN m(-1)) moduli, coupled with low bending rigidities (10(-19) N m), vesicular shells bend readily but resist volume compression and tolerate only a limited area expansion (∼5%). Consequently, vesicles experiencing solute concentration gradients dissipate the available chemical energy through the osmotic movement of water, producing dramatic shape transformations driven by surface-area-volume changes and sustained by the incompressibility of water and the flexible membrane interface. Upon immersion in a hypertonic bath, an increased surface-area-volume ratio promotes large-scale morphological remodeling, reducing symmetry and stabilizing unusual shapes determined, at equilibrium, by the minimal bending-energy configurations. By contrast, when subjected to a hypotonic bath, walls of giant vesicles lose their thermal undulation, accumulate mechanical tension, and, beyond a threshold swelling, exhibit remarkable oscillatory swell-burst cycles, with the latter characterized by damped, periodic oscillations in vesicle size, membrane tension, and phase behavior. This cyclical pattern of the osmotic influx of water, pressure, membrane tension, pore formation, and solute efflux suggests quasi-homeostatic self-regulatory behavior allowing vesicular compartments produced from simple molecular components, namely, water, osmolytes, and lipids, to sense and regulate their microenvironment in a negative feedback loop.
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Affiliation(s)
- James C S Ho
- Centre for Biomimetic Sensor Science, School of Materials Science & Engineering, Nanyang Technological University , Singapore 637553
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California-San Diego , La Jolla, California 92093, United States
| | - Bo Liedberg
- Centre for Biomimetic Sensor Science, School of Materials Science & Engineering, Nanyang Technological University , Singapore 637553
| | - Atul N Parikh
- Centre for Biomimetic Sensor Science, School of Materials Science & Engineering, Nanyang Technological University , Singapore 637553
- Departments of Biomedical Engineering and Chemical Engineering & Materials Science, University of California-Davis , Davis, California 95616, United States
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44
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Abstract
The fundamental mechanisms of protein and lipid organization at the plasma membrane have continued to engage researchers for decades. Among proposed models, one idea has been particularly successful which assumes that sterol-dependent nanoscopic phases of different lipid chain order compartmentalize proteins, thereby modulating protein functionality. This model of membrane rafts has sustainably sparked the fields of membrane biophysics and biology, and shifted membrane lipids into the spotlight of research; by now, rafts have become an integral part of our terminology to describe a variety of cell biological processes. But is the evidence clear enough to continue supporting a theoretical concept which has resisted direct proof by observation for nearly twenty years? In this essay, we revisit findings that gave rise to and substantiated the raft hypothesis, discuss its impact on recent studies, and present alternative mechanisms to account for plasma membrane heterogeneity.
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Affiliation(s)
- Eva Sevcsik
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria
| | - Gerhard J Schütz
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria
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45
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Bilayer membrane interactions with nanofabricated scaffolds. Chem Phys Lipids 2015; 192:75-86. [DOI: 10.1016/j.chemphyslip.2015.07.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/16/2015] [Accepted: 07/25/2015] [Indexed: 01/17/2023]
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46
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Jung J, Mori T, Kobayashi C, Matsunaga Y, Yoda T, Feig M, Sugita Y. GENESIS: a hybrid-parallel and multi-scale molecular dynamics simulator with enhanced sampling algorithms for biomolecular and cellular simulations. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2015; 5:310-323. [PMID: 26753008 PMCID: PMC4696414 DOI: 10.1002/wcms.1220] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 03/12/2015] [Accepted: 03/23/2015] [Indexed: 12/18/2022]
Abstract
GENESIS (Generalized-Ensemble Simulation System) is a new software package for molecular dynamics (MD) simulations of macromolecules. It has two MD simulators, called ATDYN and SPDYN. ATDYN is parallelized based on an atomic decomposition algorithm for the simulations of all-atom force-field models as well as coarse-grained Go-like models. SPDYN is highly parallelized based on a domain decomposition scheme, allowing large-scale MD simulations on supercomputers. Hybrid schemes combining OpenMP and MPI are used in both simulators to target modern multicore computer architectures. Key advantages of GENESIS are (1) the highly parallel performance of SPDYN for very large biological systems consisting of more than one million atoms and (2) the availability of various REMD algorithms (T-REMD, REUS, multi-dimensional REMD for both all-atom and Go-like models under the NVT, NPT, NPAT, and NPγT ensembles). The former is achieved by a combination of the midpoint cell method and the efficient three-dimensional Fast Fourier Transform algorithm, where the domain decomposition space is shared in real-space and reciprocal-space calculations. Other features in SPDYN, such as avoiding concurrent memory access, reducing communication times, and usage of parallel input/output files, also contribute to the performance. We show the REMD simulation results of a mixed (POPC/DMPC) lipid bilayer as a real application using GENESIS. GENESIS is released as free software under the GPLv2 licence and can be easily modified for the development of new algorithms and molecular models. WIREs Comput Mol Sci 2015, 5:310–323. doi: 10.1002/wcms.1220
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Affiliation(s)
- Jaewoon Jung
- Computational Biophysics Research Team, RIKEN Advanced Institute for Computational Science Kobe, Japan
| | - Takaharu Mori
- Theoretical Molecular Science Laboratory, RIKEN Wako-shi, Japan
| | - Chigusa Kobayashi
- Computational Biophysics Research Team, RIKEN Advanced Institute for Computational Science Kobe, Japan
| | - Yasuhiro Matsunaga
- Computational Biophysics Research Team, RIKEN Advanced Institute for Computational Science Kobe, Japan
| | - Takao Yoda
- Nagahama Institute of Bio-Science and Technology Nagahama, Japan
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, and Department of Chemistry, Michigan State University East Lansing, MI, USA
| | - Yuji Sugita
- Computational Biophysics Research Team, RIKEN Advanced Institute for Computational Science Kobe, Japan; Theoretical Molecular Science Laboratory, RIKEN Wako-shi, Japan; Interdisciplinary Theoretical Science Research Group, RIKEN Wako-shi, Japan; Laboratory for Biomolecular Function Simulation, RIKEN Quantitative Biology Center Kobe, Japan
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47
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Chen D, Santore MM. Hybrid copolymer-phospholipid vesicles: phase separation resembling mixed phospholipid lamellae, but with mechanical stability and control. SOFT MATTER 2015; 11:2617-26. [PMID: 25687473 DOI: 10.1039/c4sm02502d] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Vesicles whose bilayer membranes contain phospholipids mixed with co-polymers or surfactants comprise new hybrid materials having potential applications in drug delivery, sensors, and biomaterials. Here we describe a model polymer-phospholipid hybrid membrane system exhibiting strong similarities to binary phospholipid mixtures, but with more robust membrane mechanics. A lamella-forming graft copolymer, PDMS-co-PEO (polydimethylsiloxane-co-polyethylene oxide) was blended with a high melting temperature phospholipid, DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine), over a broad compositional range. The resulting giant hybrid unilamellar vesicles were compared qualitatively and quantitatively to analogous mixed phospholipid membranes in which a low melting temperature phospholipid, DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine), was blended with DPPC. The mechanical properties of the hybrid vesicles, even when phase separated, were robust with high lysis stresses and strains approaching those of the pure copolymer vesicles. The temperature-composition phase diagram of the hybrid vesicles closely resembled that of the mixed phospholipids; with only slightly greater nonidealities in the hybrid compared with DOPC/DPPC mixed membranes. In both systems, it was demonstrated that tension could be used to manipulate DPPC solidification into domains of patchy or striped morphologies that exhibited different tracer incorporation. The patch and stripe-shaped domains are thought to be different solid DPPC polymorphys: ripple and tilt (or gel). This work demonstrates that in mixed-phospholipid bilayers where a high-melting phospholipid solidifies on cooling, the lower-melting phospholipid may be substituted by an appropriate copolymer to improve mechanical properties while retaining the underlying membrane physics.
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Affiliation(s)
- Dong Chen
- Department of Physics, University of Massachusetts at Amherst, 120 Governors Drive, Amherst, MA 01003, USA
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Sacchi M, Balleza D, Vena G, Puia G, Facci P, Alessandrini A. Effect of neurosteroids on a model lipid bilayer including cholesterol: An Atomic Force Microscopy study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1258-67. [PMID: 25620773 DOI: 10.1016/j.bbamem.2015.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 12/18/2014] [Accepted: 01/02/2015] [Indexed: 12/20/2022]
Abstract
Amphiphilic molecules which have a biological effect on specific membrane proteins, could also affect lipid bilayer properties possibly resulting in a modulation of the overall membrane behavior. In light of this consideration, it is important to study the possible effects of amphiphilic molecule of pharmacological interest on model systems which recapitulate some of the main properties of the biological plasma membranes. In this work we studied the effect of a neurosteroid, Allopregnanolone (3α,5α-tetrahydroprogesterone or Allo), on a model bilayer composed by the ternary lipid mixture DOPC/bSM/chol. We chose ternary mixtures which present, at room temperature, a phase coexistence of liquid ordered (Lo) and liquid disordered (Ld) domains and which reside near to a critical point. We found that Allo, which is able to strongly partition in the lipid bilayer, induces a marked increase in the bilayer area and modifies the relative proportion of the two phases favoring the Ld phase. We also found that the neurosteroid shifts the miscibility temperature to higher values in a way similarly to what happens when the cholesterol concentration is decreased. Interestingly, an isoform of Allo, isoAllopregnanolone (3β,5α-tetrahydroprogesterone or isoAllo), known to inhibit the effects of Allo on GABAA receptors, has an opposite effect on the bilayer properties.
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Affiliation(s)
- Mattia Sacchi
- Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Via Campi 213/A, 41125 Modena, Italy; CNR - Istituto Nanoscienze, S3, Via Campi 213/A, 41125 Modena, Italy
| | - Daniel Balleza
- CNR - Istituto Nanoscienze, S3, Via Campi 213/A, 41125 Modena, Italy
| | - Giulia Vena
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via Campi 287, Modena 287, Italy
| | - Giulia Puia
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via Campi 287, Modena 287, Italy
| | - Paolo Facci
- CNR - Istituto di Biofisica, Via De Marini 6, 16149 Genova, Italy
| | - Andrea Alessandrini
- Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Via Campi 213/A, 41125 Modena, Italy; CNR - Istituto Nanoscienze, S3, Via Campi 213/A, 41125 Modena, Italy.
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Three dimensional (temperature–tension–composition) phase map of mixed DOPC–DPPC vesicles: Two solid phases and a fluid phase coexist on three intersecting planes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2788-97. [DOI: 10.1016/j.bbamem.2014.07.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/23/2014] [Accepted: 07/16/2014] [Indexed: 02/02/2023]
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Oglęcka K, Rangamani P, Liedberg B, Kraut RS, Parikh AN. Oscillatory phase separation in giant lipid vesicles induced by transmembrane osmotic differentials. eLife 2014; 3:e03695. [PMID: 25318069 PMCID: PMC4197780 DOI: 10.7554/elife.03695] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 09/19/2014] [Indexed: 01/14/2023] Open
Abstract
Giant lipid vesicles are closed compartments consisting of semi-permeable shells, which isolate femto- to pico-liter quantities of aqueous core from the bulk. Although water permeates readily across vesicular walls, passive permeation of solutes is hindered. In this study, we show that, when subject to a hypotonic bath, giant vesicles consisting of phase separating lipid mixtures undergo osmotic relaxation exhibiting damped oscillations in phase behavior, which is synchronized with swell-burst lytic cycles: in the swelled state, osmotic pressure and elevated membrane tension due to the influx of water promote domain formation. During bursting, solute leakage through transient pores relaxes the pressure and tension, replacing the domain texture by a uniform one. This isothermal phase transition--resulting from a well-coordinated sequence of mechanochemical events--suggests a complex emergent behavior allowing synthetic vesicles produced from simple components, namely, water, osmolytes, and lipids to sense and regulate their micro-environment.
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Affiliation(s)
- Kamila Oglęcka
- Division of Molecular Genetics and Cell Biology, School of Biological Sciences, Nanyang Technological University, Nanyang, Singapore
| | - Padmini Rangamani
- Department of Molecular and Cellular Biology, University of California, Berkeley, Berkeley, United States
| | - Bo Liedberg
- School of Materials Science and Engineering, Nanyang Technological University, Nanyang, Singapore
| | - Rachel S Kraut
- Division of Molecular Genetics and Cell Biology, School of Biological Sciences, Nanyang Technological University, Nanyang, Singapore
| | - Atul N Parikh
- School of Materials Science and Engineering, Nanyang Technological University, Nanyang, Singapore
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