Temperature scanning simultaneous small- and wide-angle X-ray scattering studies on glycolipid vesicles: areas, expansion coefficients and hydration

Hydrophilic/Hydrophobic Balance Determines Morphology of Glycolipids with Oligolactose Headgroups

“…Morphology of synthetic glycolipids with mono-or disaccharide headgroups has intensively been studied (Sen et al, 1982;Mannock et al, 1994;Hinz et al, 1991). However, only several reports have been conducted on the glycolipids with linear oligosaccharide headgroups (Hinz et al, 1991;Hato and Minamikawa, 1996;Tamada et al, 1996;Köberl et al, 1998;Hato et al, 1999;Saxena et al, 2000).Recently, we reported the thermodynamic properties and swelling behavior of ether-linked glyco-glycerolipids with linear oligolactose headgroups (Schneider et al, 2001). We demonstrated that thermodynamic properties of the glycolipid monolayers at air/water interface are comparable to that of ordinary phospholipids, despite the lower degree of cooperativity between the larger headgroups.…”

“…Here, the wide-angle patterns at T , T t (T ¼ 208C) can be characterized with only one sharp scattering peak at 4.17 Å , which corresponds to the gel (L b ) phase. The absence of a pronounced shoulder denotes that the alkyl chains have nearly no tilts (Hinz et al, 1991;Köberl et al, 1998). No correlation between the lactose headgroups could be seen, indicating that the headgroups are already hydrated in this phase.…”

“…The scattering peak at 4.45 Å corresponds to the alkyl chains in the lamellar crystalline (L C ) phase with a triclinic packing mode (Larrson, 1988). On the other hand, the peak at 7.50 Å can be interpreted as the first order peak due to the strong correlation between dehydrated headgroups (Caffrey, 1987;Hinz et al, 1991;Köberl et al, 1998;Seddon et al, 1984). The other peak at 3.76 Å can be related either to 1), the complex chain packing modes, e.g., the hybrid lattice of orthorhombic and triclinic (Köberl et al, 1998;Saxena et al, 2000), or to 2), the second order peak of the headgroup correlation peak at 7.50 Å .…”

Fast real-time monitoring of entacapone crystallization and characterization of polymorphs via Raman spectroscopy, statistics and SWAXS

“…Further insight both into the API content and the structure in the solid state can be obtained by off-line methods, and X-ray scattering techniques are ideal for this purpose. Thus, small and wide angle X-ray scattering techniques (SWAXS) have been used to assess the API and excipient content (20), to investigate the effects of process variables on the crystalline state of powders, granules and tablets (21) and to study interactions between the model's membranes and biologically active compounds (22,23). This paper describes in-line crystallization monitoring of the drug entacapone via Raman spectroscopy and multivariate methods involving principal components analysis (PCA) and indirect hard modeling (IHM) as well as off-line characterization of the obtained polymorphic forms using Raman spectroscopy and SWAXS.…”

Structural polymorphism of hydrated monoacylated maltose glycolipids

“…In the first scan, there is a transition of the s (CH 2 ) band in the gel phase at about 57 • C from 2849 to 2853.3 cm −1 of the s (CH 2 ) band to the liquid-crystalline phase. In For the glycolipid Mal-␤-OC 2 -NH-COC 15 the s (CH 2 ) band in the gel phase was observed at 2849.5-2850.0 cm −1 and a gel/liquid crystalline phase transition was observed at T m = 60 • C. The subsequent cooling scan showed considerable hysteretic behaviour, with a condensation of the lipid into the gel phase at around 12 • C (Köberl et al, 1997(Köberl et al, , 1998. Finally, Mal-␤-OC 2 -NH-COC 17:1 with its unsaturated C17:1 chain is already fluid at −30 • C, and exhibits no clear phase transition in the temperature range investigated between −30 to 50 • C. Fig.…”