Speaker
Description
The self-assembly of small unilamellar vesicles (SUVs) in mixtures of perfluorinated and hydrocarbon surfactants has been subject of intense studies in the past with a focus on the phase diagram [1,2], shape and kinetics of the aggregates depending on concentration and mixing ratio [3] as well as control thereof [4].
Given that the scattering length densities (SLD) of perfluorinated and hydrocarbon surfactant tails differ largely for both neutron and x-ray scattering, SANS and SWAXS are very sensitive to the composition as well as the internal structure of the bilayer [5].
Using contrast-variation SANS (KWS-1, FRM II), we were recently able to show that the composition of our SUVs differs significantly from the sample composition even for a nearly symmetric mixture (mole fraction $x_{\mathrm{TDMAO}}~=~0.43$).
We are currently improving our structural model based on this finding in order to fully exploit the detailed structural information contained in our stopped-flow SAXS/WAXS data (ID02, ESRF) [6]. These results then are correlated with a thermodynamic analysis of the system.
References:
[1] C. Wolf et al., Langmuir 25(19):11358, 2009.
[2] K. Bressel et al., Soft Matter 7(23):11232, 2011.
[3] J. Gummel et al., Soft Matter 7(12):5731, 2011.
[4] K. Bressel et al., ACS Nano 6(7):5858, 2012.
[5] T. Narayanan et al., chap. 7 in Advances in Planar Lipid Bilayers and Liposomes,
vol. 20, Academic Press 2014.
[6] A. F. Hörmann et al., in preparation.
