TY  - JOUR
A1  - Teixeira, C. V.
A1  - Blanzat, Muriel
A1  - Koetz, Joachim
A1  - Rico-Lattes, I.
A1  - Brezesinski, Gerald
T1  - In-plane miscibility and mixed bilayer microstructure in mixtures of catanionic glycolipids and zwitterionic phospholipids
JF  - Biochimica et biophysica acta : Biomembranes
N2  - SAXS/WAXS studies were performed in combination with freeze fracture electron microscopy using mixtures of a new Gemini catanionic surfactant (Gem 16-12, formed by two sugar groups bound by a hydrocarbon spacer with 12 carbons and two 16-carbon chains) and the zwitterionic phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine(DPPC) to establish the phase diagram. Gem 16-12 in water forms bilayers with the same amount of hydration water as DPPC. A frozen interdigitated phase with a low hydration number is observed below room temperature. The kinetics of the formation of this crystalline phase is very slow. Above the chain melting temperature, multilayered vesicles are formed. Mixing with DPPC produces mixed bilayers above the corresponding chain melting temperature. At room temperature, partially lamellar aggregates with local nematic order are observed. Splitting of infinite lamellae into discs is linked to immiscibility in frozen state. The ordering process is always accompanied by dehydration of the system. As a consequence, an unusual order-disorder phase transition upon cooling is observed.
KW  - SAXS
KW  - bilayer
KW  - gemini surfactant
KW  - ordering process
KW  - Anti-HIV
KW  - miscibility
Y1  - 2006
U6  - https://doi.org/10.1016/j.bbamem.2006.05.025
SN  - 0005-2736
VL  - 1758
SP  - 1797
EP  - 1808
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Schulze, Nicole
A1  - Tiersch, B.
A1  - Zenke, I.
A1  - Koetz, Joachim
T1  - Polyampholyte-tuned lyotrop lamellar liquid crystalline systems
JF  - COLLOID AND POLYMER SCIENCE
N2  - The influence of a polyampholyte, i.e., poly(N,N’-diallyl-N,N’-dimethyl-altmaleamic carboxylate) (PalH), on the lamellar liquid crystalline (LC) system sodium dodecyl sulfate (SDS)/decanol/water was investigated by means of microdifferential scanning calorimetry, small-angle X-ray diffraction (SAXS), and cryo-scanning electron microscopy. After incorporating PalH into the lamellar liquid crystalline system, SAXS measurements show that three different LC phases exist: i.e., a swelling, slightly swelling, and non-swelling one. At pH 4, the positively charged polymer with an extended conformation can directly adsorb at the anionic head groups of the surfactant and more compact vesicles are formed at room temperature. At pH 9, the electrostatic interactions between the polyampholyte (in a more coiled conformation) and the sulfate head groups of the SDS are leveled off and incompact vesicles are formed at room temperature. That means in presence of the polyampholyte the morphology of the LC phase, i.e., the supramolecular vesicle structure, can be tuned by varying the pH and/or the temperature.
KW  - Polyampholytes
KW  - Lamellar liquid crystals
KW  - Vesicle formation
KW  - SAXS
KW  - Cryo-SEM
KW  - mu-DSC
Y1  - 2013
U6  - https://doi.org/10.1007/s00396-013-2999-5
SN  - 0303-402X
SN  - 1435-1536
VL  - 291
IS  - 11
SP  - 2551
EP  - 2559
PB  - SPRINGER
CY  - NEW YORK
ER  -