Monolayer curvature

REPULSIVE HEAD-GROUP INTERACTIONS AND MONOLAYER CURVATURE... 

This may not be the case when the model system is a small unilamellar vesicle in which the monolayer curvatures are significantly different for the inner and outer monolayer. If these vesicles are prepared from a mixture of lipids, the inner monolayer may be expected preferentially to contain that lipid species that has a more negative spontaneous curvature at the bilayer water interface. 

Aveyard R, Clint JH, Horozov TS (2003) Aspects of the stabilisation of emulsions by solid particles effects of line tension and monolayer curvature energy. Phys Chem Chem Phys 5(ll) 2398-2409... 

Of course, a direct demonstration of the effects of lipid monolayer curvature on membrane proteins is desirable. Biochemists have long been... 

Chen et al. [74] successftilly used fluorescence polarization of an amphiphilic and an oil-soluble probe to monitor the changes of monolayer curvature within the microemulsion phase in didodecyldimethylammonium bromide (DDAB)-alkane-water. 

The stability of foams and emulsions depends critically on whether formation of a stable Newton black film or a hole leading to coalescence is favored. Kabalnov and Wen-nerstrom (4) addressed this question by developing a temperature-induced hole nuclea-tion model applicable to emulsions. They point on that the coalescene energy barrier is strongly affected by flic spontaneous monolayer curvature. The aufliors consider a flat emulsion film, covered by a saturated surfactant monolayer, in thermodynamic equi-... 

Clearly, the siuface tension has a minimum when the spontaneous curvature of the surfactant film equals the mean ciuvature of the interface. The mean curvature for a flat interface is zero, larger than zero for an interface curving towards the oil (oil-in-water emulsions), and smaller than zero for a water-in-oil emulsion. Hence, a large positive spontaneous monolayer curvature, as for a strongly hydro-philic surfactant, favors oil-in-water emulsions and vice versa. The Kabalnov-Wennerstrom model also allows the thickness of the film to vary in order to minimize the free energy of hole formation, i.e., the mean curvature of... 

The particular feature with ethylene oxide based surfactants is that their interaction with water is less favorable at higher temperatures. This leads to a decrease in the spontaneous monolayer curvature with temperature, explaining the transition from oil-in-water emulsions below the PIT to water-in-oil emulsion above the PIT. In the vicinity of the phase inversion temperature the energy barrier against co-alescence(lP) varies very strongly with temperature. For the system n-octane-Cj2E5-water the following approximate relation was obtained in terms of AT = T-Tj, where is the PIT (4) ... 

Meinhardt S, Vink R, Schmid F (2013) Monolayer curvature stabilizes nanoscale raft domains in mixed lipid bilayers. Proc Natl Acad Sci USA 12 4476-4481... 

The possibility of tuning ic is not the only advantage offered by mixed bilayers. Another is a decrease of the bending rigidity which arises when the surfactant molecules differ by their monolayer spontaneous curvatures [6, 37]. It reflects an adjustment of the local surfactant concentrations to the local monolayer curvature or, so to speak, of spontaneous to actual monolayer curvature. 

---