Bilayer bending rigidity of some synthetic lecithins

Beblik, G.; Servuss, R.M.; Helfrich, W.

doi:10.1051/jphys:0198500460100177300

Cited by 77 publications

(30 citation statements)

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“…k is determined from the equilibrium distribution of thermally excited bending fluctuations of tubular vesicles [11]. The lowest value for k we found in this way is ͑8 6 2͒k B T , but also multiples of this value were found, thus corroborating the microscopy observations that the vesicles are multilamellar.…”

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confidence: 85%

Large Deformations of Giant Floppy Vesicles in Shear Flow

et al. 1998

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The flow deformation and rheology of vesicles of a soluble surfactant are studied. Direct observation under shear flow reveals that the vesicles become strongly elongated to form an entangled structure of connected bilayer tubes. The large deformation is due to the permeability of the membrane and the large solubility of the surfactant. The formation of the entangled structure is observed in the rheology as a strong increase of the viscosity with time. [S0031-9007(98)07534-6] PACS numbers: 87.45.FtVesicles are closed membranes consisting of surfactant bilayers and have been intensively studied as model systems for biological cells [1]. More recently, the problem of the deformation of vesicles in hydrodynamic flows has been considered [2][3][4][5][6]. From a fundamental point of view, this is an interesting problem since both the surface area of the vesicle and its interior volume are usually supposed to be fixed [5,6]: The response to flow is then attributed to a dynamic surface tension. There is also a biological motive for understanding vesicle deformation in flow. One example is that of red blood cells, which are also vesicular structures. These have the capacity to pass through capillaries that are smaller than their own diameter, due to the deformation they undergo in the flow [7].The flexibility or "floppiness" of vesicles at rest is determined by their bending rigidity k, through the persistence length j of the membrane: j a exp͑2pk͞k B T͒, with a a molecular length, k B Boltzmann's constant, and T temperature [8]. If k ¿ k B T , j is large and the vesicle remains flat over large distances in the presence of thermal fluctuations. If k ø k B T , thermal fluctuations dominate, and the vesicle will appear very "floppy."In a dynamical situation, for instance, under flow, if the total volume within the vesicle does not change, conservation of the number of surfactant molecules in the membrane (conserved surface area) leads to a dynamic "effective" surface tension s e , which also contributes to the response of a vesicle in a flow field [5,6].Model vesicles are usually prepared from phospholipids, practically insoluble surfactants. A recent detailed study of the flow deformation shows that it is in general very small, and that even for high shear rates ͑ഠ18 s 21 ͒, the ratio of long and short axes of the vesicles L͞S ഠ 1.3: No large deformations are observed [4]. The deformation could be well described using the fixed area and volume constraints, allowing for evaluation of k and s e [4]. The two constraints thus lead to small deformations [4-6], accompanied by a "tank treading" motion, in which the membrane revolves around the vesicle interior [3,4].In this Letter we report extremely large deformations ͑L͞S ¿ 100͒ for vesicles that form spontaneously [9] in solutions of a soluble surfactant, even for very weak shear ͑ഠ0.5 s 21 ͒. Moreover, k for these vesicles is similar to that of phospholipid vesicles [4]: both are on the order of a few k B T . The large deformation entails the formation of very long and thin,...

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confidence: 85%

Large Deformations of Giant Floppy Vesicles in Shear Flow

et al. 1998

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“…On the other hand, the swelling of DLPE, which differs from DMPE only by two carbons less in the saturated hydrocarbon chains, produced some suitable tubes but no extended membranes. The measurement of the angular distribution function and the calculation of the bending rigidity from its width have been described elsewhere [1,2]. The results of our experiments, three with unilamellar and two with multilamellar tubes, are listed in table II.…”

Section: Dilauroyl-phosphatidylethanolaminementioning

confidence: 99%

“…The first value, kc = 2.3 x 10 -12 erg, was obtained for egg lecithin (EYPC) membranes from the fluctuations of the angle made by the two ends of long tubular vesicles [1]. Later on, the same method was applied, apart from EYPC, to dimyristoyl-lecithin (DMPC), dipalmitoyl-lecithin and distearoyl-lecithin, yielding bending rigidities in the range of (1.8 -2.4 ) x 10-12 erg [2]. Studying fluctuation amplitudes and relaxation times of tubular and spherical vesicles, Schneider et al found kc = (1 -2) x 10-12 erg for the bending rigidity of the EYPC bilayer [3,4].…”

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“…1 Vu 1 « 1, we may express the sum of curvatures by The curvature elastic energy associated with a pair of modes is then readily seen to be In the presence of lateral tension a, a further contribution to the deformational energy results from the fact that the thermal undulations absorb membrane area. The extra area per unit basal area being 1 (VU)2 for ou 1 « 1, one obtains as absorbed area per pair of modes 2 The addition of deformational energy is taken into account in calculating the mean-square fluctuation amplitudes from the equipartition theorem. The mean energy of deformation per pair of modes being kB T, one has because of (5) to (7) Let the x axis be in the focal plane of the microscope and the y axis coincide with the direction of viewing.…”

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Bending rigidities of some biological model membranes as obtained from the Fourier analysis of contour sections

1990

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2014 We have measured the bending rigidites kc of egg lecithin (EYPC), dimyristoylphosphatidyl-ethanolamine (DMPE) and digalactosyl-diacylglycerol (DGDG) membranes in the fluid state, subjecting the fluctuations of large nearly planar bilayer sections to computerized Fourier analysis. For EYPC we found kc = 0.8 10-12 erg which is less than half the value obtained earlier for egg and other lecithins from the bending fluctuations of tubular vesicles but in the range of more recent measurements on spherical lecithin vesicles. For DMPE we found kc = 0.7 x 10-12 erg at T = 60 °C, while we derived kc = 1.7 x 10-12 erg from the bending fluctuations of tubular vesicles of dilauroyl-phosphatildylethanolamine (DLPE) at T = 46 °C. As in the case of lecithins the different results seem to be mostly due to the different methods. Very low values of kc = (0.12 2014 0.27) x 10-12 erg were measured for DGDG. The scatter was less but also large for the other materials.

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“…28 A compilation of  values from the literature is shown in Table 1. 29,30,31,32 (It should be noted that these values tend to be somewhat variable depending on the measuring technique and conditions.) These data provide a minimal basis for rationalizing a correlation of the contribution of membrane bending energy to spontaneous tubulation by protein binding interactions.…”

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confidence: 99%

Biomolecular transport and separation in nanotubular networks.

Stachowiak¹,

Stevens

Robinson³

et al. 2010

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Cell membranes are dynamic substrates that achieve a diverse array of functions through multi-scale reconfigurations. We explore the morphological changes that occur upon protein interaction to model membrane systems that induce deformation of their planar structure to yield nanotube assemblies. In the two examples shown in this report we will describe the use of membrane adhesion and particle trajectory to form lipid nanotubes via mechanical stretching, and protein adsorption onto domains and the induction of membrane curvature through steric pressure. Through this work the relationship between membrane bending rigidity, protein affinity, and line tension of phase separated structures were examined and their relationship in biological membranes explored.

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Bilayer bending rigidity of some synthetic lecithins

Cited by 77 publications

References 20 publications

Large Deformations of Giant Floppy Vesicles in Shear Flow

Large Deformations of Giant Floppy Vesicles in Shear Flow

Bending rigidities of some biological model membranes as obtained from the Fourier analysis of contour sections

Biomolecular transport and separation in nanotubular networks.

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