In‐Plane Structures of Synthetic Oligolactose Lipid Monolayers—Impact of Saccharide Chain Length

Abstract

Grazing incidence X-ray diffraction (GIXD) was used to investigate the in-plane structure of monolayers of synthetic glycolipids with oligolactose head groups (Lac N, with N = number of lactose units) at the air/water interface. The Lac 1 monolayer exhibits three sharp diffraction peaks. One peak can be deconvoluted into two diffraction peaks, which suggests that alkyl chains in the monolayer form an orthorhombic lattice. On the other hand, the other two peaks are related to bulk crystalline materials residing at the interface. Another weak peak from the head group correlation, either in a monolayer or in bulk crystals, can also be observed in some experiments. The scattering patterns of the Lac 2 monolayer indicate that the alkyl chains order in an orthorhombic lattice, where a shift in the hydrophilic/hydrophobic balance seems to fluidize the film. Alkyl chains in the Lac 3 monolayer also seem to assume an orthorhombic lattice; however, a weak diffraction peak from the correlation between trilactose head groups can also be observed. The estimated lattice dimensions are compared systematically to those of bulk dispersions, as well as to the viscoelastic properties of the monolayer. The obtained results strongly suggest that the in-plane structure of synthetic glycolipid monolayers can provide a well-defined basis to understand the impact of the chemical structure on the cooperativity and function of the glycocalix of cellular surfaces.

Modifying dipalmitoylphosphatidylcholine monolayers by n-hexadecanol and dipalmitoylglycerol

“…A xy can be calculated from the lattice parameters that are derived from the lattice spacing d = 2/Q xy (Tanaka et al, 2003). The area occupied by a single molecule at the aqueous buffer/air interface is obtained by multiplying A xy by the number of alkyl chains per molecule.…”

“…Q xy provides information about the laterally periodic structure of the monolayer, whereas Q z gives information about the tilt angle and the tilt direction of lipid chains. The experimental setup and evaluation procedure have been described in detail elsewhere (Jensen and Kjaer, 2001;Als-Nielsen et al, 1994;Kjaer, 1994;Tanaka et al, 2003). Fig.…”

Do unsaturated phosphoinositides mix with ordered phosphadidylcholine model membranes?

“…The out-of-plane [Q z ≈ (2p/l)·sin(a f )] and inplane [Q xy ≈ (4p/l)·sin(2u xy /2)] components of the scattering vector Q provide information about the laterally periodic structures of the monolayer in terms of lattice parameters, tilt angle, tilt direction, and lattice distortion. Detailed descriptions of the experimental set-up and the theoretical background of the GIXD experiment can be found in the literature (10)(11)(12).…”

Bacterial lipopolysaccharides form physically cross-linked, two-dimensional gels in the presence of divalent cations

“…The technique has been applied to monolayers of (i) synthetic surfactants, (ii) block copolymers and lipopolymers, and (iii) biological surfactants. 33,35 In the present paper, we extend this strategy to study the mechanical properties of LPS monolayers. In particular, we studied the influence of the length and conformation of saccharide head groups on the monolayer mechanics.…”