Phase diagram of and . and denote the micellar and the lamellar phase, respectively. is the hexagonal phase, and and the inverse micellar and the solid phase. is the cubic phase. is a sponge phase. Unnamed areas are bicontinuous. The component ratios that were measured are marked with gray dots. The image was redrawn from Mitchell et al. (Ref. 27).
Structures of (a) R18 and (b) cholesterol.
Sketch of the orientation model: In the lamellar phase, molecular diffusion is thought to be restricted to two-dimensional planes intersecting the focus intensity distribution at arbitrary angles and vertical intercepts. Integrating the contributions from different orientations results in an effective angle .
Confocal microscope setup for FCS and schematic of the observation volume with half-axes and (enlarged).
FCS data for the micellar phase. The diffusion time in this example is .
Example for the FCS data from the surfactant/cholesterol/water emulsion. The experimental data (crosses) are compared to best fits using the standard (single-component) model (dashed-dotted line) and to the orientation model (full line). The cholesterol to surfactant ratio was 0.172. The diffusion times are (standard model) and (orientation model).
Result for the diffusion coefficient of R18 in the lamellar phase with surfactant. The molar ratio of cholesterol to surfactant increases to the right. A reduction in molecular mobility is apparent at a ratio of 0.08. Error bars denote the standard deviation. Guidelines for the eyes are drawn as dashed lines.
Diffusion coefficients for the surfactant emulsion as a function of the cholesterol content.
Counts/molecule value (cpm) as a function of cholesterol content from the same sample on two different days. The brightness is reduced by increasing cholesterol content.
The table subsumes the amount of substances used in the microemulsions. The ratio value gives the molar ratio of cholesterol vs . The lipid frac. value denotes the fraction of and cholesterol.
Overview of diffusion coefficients in /water/cholesterol emulsions determined from the orientation model.
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