Membrane Curvature Induced by Sugar and Polymer Solutions

1997 ◽  
Vol 489 ◽  
Author(s):  
H.-G. Döbereiner ◽  
A. Lehmann ◽  
W. Goedel ◽  
O. Selchow ◽  
R. Lipowsky
Keyword(s):  
Polymer Solutions ◽  
Lipid Vesicles ◽  
Membrane Curvature ◽  
Elastic Membrane ◽  
Spontaneous Curvature ◽  
Membrane Asymmetry ◽  
Bending Modulus ◽  
Bending Elasticity ◽  
Cellular Organelles

AbstractWe monitor the effect of transversal membrane asymmetry on the morphology of giant uni-lamellar vesicles in sugar and polymer solutions. The shapes of fluid lipid vesicles are governed by the bending elasticity of their membrane which is characterized by the bending modulus and the spontaneous curvature of the bilayer. We present a recently developed technique for the measurement of the spontaneous curvature using quantitative phase contrast microscopy. Different mechanisms for elastic membrane asymmetry and the role of the bending energy concept for the morphology of cellular organelles are discussed.

scholarly journals Membrane Curvature, Trans-Membrane Area Asymmetry, Budding, Fission and Organelle Geometry

2020 ◽  
Vol 21 (20) ◽  
pp. 7594
Author(s):  
Alexander A. Mironov ◽  
Anna Mironov ◽  
Jure Derganc ◽  
Galina V. Beznoussenko
Keyword(s):  
Lipid Bilayer ◽  
Cellular Membrane ◽  
Membrane Curvature ◽  
Membrane Area ◽  
Membrane Asymmetry ◽  
Geometrical Properties ◽  
Surface Areas ◽  
Acyl Chains ◽  
Specific Shape

In biology, the modern scientific fashion is to mostly study proteins. Much less attention is paid to lipids. However, lipids themselves are extremely important for the formation and functioning of cellular membrane organelles. Here, the role of the geometry of the lipid bilayer in regulation of organelle shape is analyzed. It is proposed that during rapid shape transition, the number of lipid heads and their size (i.e., due to the change in lipid head charge) inside lipid leaflets modulates the geometrical properties of organelles, in particular their membrane curvature. Insertion of proteins into a lipid bilayer and the shape of protein trans-membrane domains also affect the trans-membrane asymmetry between surface areas of luminal and cytosol leaflets of the membrane. In the cases where lipid molecules with a specific shape are not predominant, the shape of lipids (cylindrical, conical, or wedge-like) is less important for the regulation of membrane curvature, due to the flexibility of their acyl chains and their high ability to diffuse.

Mechanics of membrane–membrane adhesion

2011 ◽  
Vol 16 (8) ◽  
pp. 872-886 ◽  
Author(s):  
Ashutosh Agrawal
Keyword(s):  
Lipid Vesicles ◽  
Spontaneous Curvature ◽  
Interface Conditions ◽  
Point Boundary ◽  
Lagrange Equations ◽  
Equilibrium Conditions ◽  
Numerical Studies ◽  
Curvature Elasticity ◽  
Equilibrium Shapes ◽  
Membrane Adhesion

Curvature elasticity is used to derive the equilibrium conditions that govern the mechanics of membrane–membrane adhesion. These include the Euler–Lagrange equations and the interface conditions which are derived here for the most general class of strain energies permissible for fluid surfaces. The theory is specialized for homogeneous membranes with quadratic ‘Helfrich’-type energies with non-uniform spontaneous curvatures. The results are employed to solve four-point boundary value problems that simulate the equilibrium shapes of lipid vesicles that adhere to each other. Numerical studies are conducted to investigate the effect of relative sizes, osmotic pressures, and adhesion-induced spontaneous curvature on the morphology of adhered vesicles.

The Role of the Elastic Membrane in the Development of the Two Forms of Vascular Fibrinoid

Angiology ◽  
1970 ◽  
Vol 21 (10) ◽  
pp. 636-646 ◽  
Author(s):  
Harry Jellinek
Keyword(s):  
Elastic Membrane

Interfacial Slip Violations in Polymer Solutions:  Role of Microscale Surface Roughness

Langmuir ◽  
2003 ◽  
Vol 19 (8) ◽  
pp. 3304-3312 ◽  
Author(s):  
Javier Sanchez-Reyes ◽  
Lynden A. Archer
Keyword(s):  
Surface Roughness ◽  
Polymer Solutions ◽  
Interfacial Slip

Blocked Lipid Exchange in Bilayers and its Possible Influence on the Shape of Vesicles

1974 ◽  
Vol 29 (9-10) ◽  
pp. 510-515 ◽  
Author(s):  
W Helfrich
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Spontaneous Curvature ◽  
Lipid Exchange ◽  
Lipid Distribution ◽  
Shape Transformations ◽  
Curvature Elasticity ◽  
Possible Cause

Abstract The role of lipid exchange in the curvature elasticity of bilayers is studied theoretically. Blocking of exchange between the monolayers may give rise to a nonequilibrium lipid distribution going hand in hand with a spontaneous curvature. Some possible consequences for vesicular deformations are discussed. Lipid nonequilibrium is tentatively suggest as one possible cause for certain shape transformations of red blood cells

scholarly journals Interplay between Membrane Curvature and Cholesterol: Role of Palmitoylated Caveolin-1

2019 ◽  
Vol 116 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Anjali Krishna ◽  
Durba Sengupta
Keyword(s):  
Membrane Curvature ◽  
Caveolin 1

scholarly journals Modeling Membrane Curvature Generation due to Membrane–Protein Interactions

Biomolecules ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 120 ◽  
Author(s):  
Haleh Alimohamadi ◽  
Padmini Rangamani
Keyword(s):  
Membrane Proteins ◽  
Protein Interactions ◽  
Current Model ◽  
Bilayer Membrane ◽  
Membrane Curvature ◽  
Elastic Membrane ◽  
Protein Distribution ◽  
Membrane Models ◽  
Generation Mechanisms ◽  
Mathematical And Computational Modeling

To alter and adjust the shape of the plasma membrane, cells harness various mechanisms of curvature generation. Many of these curvature generation mechanisms rely on the interactions between peripheral membrane proteins, integral membrane proteins, and lipids in the bilayer membrane. Mathematical and computational modeling of membrane curvature generation has provided great insights into the physics underlying these processes. However, one of the challenges in modeling these processes is identifying the suitable constitutive relationships that describe the membrane free energy including protein distribution and curvature generation capability. Here, we review some of the commonly used continuum elastic membrane models that have been developed for this purpose and discuss their applications. Finally, we address some fundamental challenges that future theoretical methods need to overcome to push the boundaries of current model applications.

scholarly journals Numerical simulation of bubble dynamics in response to acoustic disturbances

2007 ◽  
Author(s):  
Κωνσταντίνος Τσιγκλιφής
Keyword(s):  
Constitutive Law ◽  
Membrane Properties ◽  
Elastic Membrane ◽  
Shear Stresses ◽  
Additional Parameter ◽  
Viscous Effects ◽  
Membrane Elasticity ◽  
Backscatter Signal ◽  
Acoustic Disturbances ◽  
Bending Modulus

The dynamic behavior and the fashion of collapse of a free bubble play a significant role in the phenomenon of single cavitation bubble luminescence (SCBL) and single bubble sono-luminescence (SBSL), in which light is emitted during its breakdown. In SCBL, the bubble is produced by the application of a laser pulse, in the host liquid, with a duration of 10⁻¹⁵ sec (femtosecond bubbles) and 10⁻⁹ sec (nanosecond bubbles). The resulting bubbles have size of the order of 5 and 500 μm, respectively. The femtosecond bubbles display severe elongation with regards to the axis of symmetry, while light is not emitted during their collapse. In contrast, the nanosecond bubbles exhibit almost spherosymmetric shape initially and collapse producing light. A parametric study is conducted on the fashion of collapse of bubbles, of various sizes, for weak or strong elongation and vanishing small or large internal overpressure, considering axisymmetric oscillations with weak viscous effects. Further, an effort is made to reproduce, as close as possible, respective SCBL and SBSL experiments, aiming to investigate the effect of the initial asymmetry on the fashion of collapse and the velocity of the resulting jet during collapse. Recently, a significant number of applications in diagnostic and therapeutic medicine use the ability of microbubbles, encapsulated by an elastic membrane (contrast agents), to reflect the ultrasound waves. Initially, a model that predicts the backscatter signal of the microbubble as a function of the membrane properties, of the host liquid and the width and the frequency of the acoustic disturbances, is presented. This model predicts with accuracy the effect of the non linear membrane constitutive law on the microbubble response for large acoustic disturbances in comparison to experimental measurements. The control of cohesion of microbubbles is desirable in several applications, such as in quantitative evaluation of heart blood flow (contrast perfusion imaging). In order to gain understanding regarding its cohesion range, the large-amplitude axisymmetric oscillation and collapse of an encapsulated microbubble is examined. The shear stresses that develop on the membrane due to the bending moments are accounted for, based on the shell stability theory, and are determined by the scalar bending modulus. This is a measure of the shell resistance to bending and is introduced as an additional parameter, due to the anisotropy of the membrane elasticity along the interface and perpendicular to it. With the help of stability analysis, it is feasible to estimate the range of the parameters for shape oscillations of the microbubble, as well as for the buckling of the shell. In combination with the model of the spherosymmetric oscillations, a theoretical tool is developed for the characterisation of a microbubble with regards to its membrane elasticity, bending resistance and viscosity. Phase diagrams are constructed where the regions of stable or unstable oscillation of a microbubble are defined. Finally, axisymmetric simulations of the interaction of the external flow field and the encapsulated microbubble are performed, implementing a hybrid boundary-finite element method, in order to determine the conditions under which a jet is created during the oscillation of the microbubble; a phenomenon which is observed when a microbubble oscillates near the walls of neighbouring tissues.

scholarly journals The role of membrane curvature for the wrapping of nanoparticles

Soft Matter ◽  
2016 ◽  
Vol 12 (2) ◽  
pp. 581-587 ◽  
Author(s):  
Amir Houshang Bahrami ◽  
Reinhard Lipowsky ◽  
Thomas R. Weikl
Keyword(s):  
Membrane Curvature

Energetic barriers for wrapping arise if the membrane initially bulges towards the nanoparticle. In contrast, stable partially wrapped states occur if the membrane initially bulges away from the nanoparticle.

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