title: Thermodynamics of membrane elasticity--a molecular level approach to one- and two-component fluid amphiphilic membranes, part II: applications.
abstract: The theoretical framework developed in the accompanying publication is applied to a number of experimentally relevant amphiphilic systems. These include the influence of thermodynamic conditions and non-ideal mixing on bending elasticity, ellipsoidal modes of microemulsions and vesicles, hydrocarbon chain coupling in bilayers and the effect of osmotic and hydrostatic pressure on inverse hexagonal (H(II)) phases. It is found that the bending moduli at constant surface tension and constant chemical potentials are markedly different only for two-component membranes and non-ideal mixing with a tendency towards phase separation. The results indicate that non-ideal mixing is the main reason behind the experimentally observed strong compositional dependence of membrane elasticity. It is generally recommended to prefer the bending elastic moduli at constant chemical potentials to those at constant surface tension. A comparison between the area-difference-elasticity (ADE) model and explicit free energy calculations using a molecular model shows a good qualitative agreement for the sphere-to-ellipsoid transition of vesicles. Results for different free energy models of the hydrocarbon chains of amphiphilic molecules suggest that monolayer-monolayer chain coupling is responsible for the relatively higher bending stiffness of bilayers compared to single monolayers. For H(II)-phases an instability at negative pressure differences is predicted.
authors.affiliation: Hans-Knöll-Institute for Natural Products Research, Beutenbergstr. 11a, 07745 Jena, Germany. martin.hoffmann@hki-jena.de
authors.forename: M
authors.initials: M
authors.lastname: Hoffmann
mesh_terms: D003198:Computer Simulation; D004548:Elasticity; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D008560:Membrane Fluidity; D008956:Models, Chemical; D008958:Models, Molecular; D012996:Solutions; D013314:Stress, Mechanical; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes; D012996:Solutions
references.citation: Biophys J. 2001 Aug;81(2):643-58
references.pmid: 11463613
references.citation: Phys Rev Lett. 2003 Jul 25;91(4):048301
references.pmid: 12906698
references.citation: Biophys J. 2000 Jul;79(1):321-7
references.pmid: 10866958
references.citation: Langmuir. 2004 Mar 16;20(6):2141-8
references.pmid: 15835663
references.citation: Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 1996 Apr;53(4):3900-3919
references.pmid: 9964703
references.citation: Biophys J. 1995 Apr;68(4):1423-9
references.pmid: 7787028
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2001 Jun;63(6 Pt 1):061406
references.pmid: 11415103
references.citation: Biophys J. 2000 Jul;79(1):328-39
references.pmid: 10866959
references.citation: Biophys J. 2002 Mar;82(3):1469-82
references.pmid: 11867462
references.citation: Biophys J. 2004 Aug;87(2):1013-33
references.pmid: 15298907
references.citation: Biochim Biophys Acta. 1998 Jan 19;1368(2):201-15
references.pmid: 9459598
references.citation: Phys Rev Lett. 2001 Jun 25;86(26 Pt 1):5930-3
references.pmid: 11415396
references.citation: Phys Rev A. 1991 Mar 15;43(6):2903-2904
references.pmid: 9905356
references.citation: Eur Biophys J. 2000;29(1):17-28
references.pmid: 10826775
references.citation: Biochim Biophys Acta. 1998 Nov 10;1376(3):401-15
references.pmid: 9805000
references.citation: Phys Rev A. 1991 Jan 15;43(2):1071-1078
references.pmid: 9905123
references.citation: Phys Rev Lett. 1989 Mar 6;62(10):1134-1137
references.pmid: 10039585
references.citation: Eur Phys J E Soft Matter. 2005 Feb;16(2):111-23
references.pmid: 15729503
references.citation: Phys Rev A Gen Phys. 1987 Nov 1;36(9):4371-4379
references.pmid: 9899393
references.citation: Biophys J. 2001 Jul;81(1):243-54
references.pmid: 11423410
references.citation: J Lipid Res. 2003 Oct;44(10 ):1940-5
references.pmid: 12867540
references.citation: Phys Rev Lett. 2004 Feb 6;92(5):056103
references.pmid: 14995321
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2003 Jan;67(1 Pt 1):012901
references.pmid: 12636543
references.citation: Biophys J. 1997 May;72(5):2196-210
references.pmid: 9129822
references.citation: Phys Rev Lett. 1993 May 31;70(22):3455-3458
references.pmid: 10053873
references.citation: Eur Phys J E Soft Matter. 2004 Mar;13(3):277-90
references.pmid: 15103522
references.citation: Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 1994 Jun;49(6):5389-5407
references.pmid: 9961866
references.citation: Science. 1990 Apr 20;248(4953):354-6
references.pmid: 17784490
references.citation: Biophys J. 1995 Sep;69(3):930-41
references.pmid: 8519993
references.citation: Biochim Biophys Acta. 1998 Apr 22;1371(1):83-95
references.pmid: 9565658
references.citation: Biochemistry. 1990 Jan 9;29(1):76-87
references.pmid: 2322550
references.citation: Eur Phys J E Soft Matter. 2004 Jun;14(2):149-67
references.pmid: 15254835
references.citation: Biophys J. 1992 Feb;61(2):434-47
references.pmid: 1547331
references.citation: Biophys J. 1994 Feb;66(2 Pt 1):377-81
references.pmid: 8161691