Figure 1.

Effect of calcium and osmotic pressure on the structure of isolated and interacting lipopolysaccharide layers. The layers were built on Si substrates that were coated by a thin (15–21 Å) SiO₂ layer (gray slab). The solid substrates were then hydrophobically functionalized with an octadecyltrichlorosilane monolayer (17 Å thick). LipidA hydrocarbon chains (14–15 Å thick), to which the core oligosaccharide (represented by hexagons) were attached, were than added. 25% of the oligosaccharide units displayed O-side chains (shown in green) consisting of polydispersed pentasaccharide repeats (average of 18 repeats per chain). (A) The effect of added 20 mM calcium ions (shown as red dots) on the structure of lipopolysaccharide monolayers at the solid/water interface is shown. (B) The effect of osmotic pressure on the structure of interacting lipopolysaccharide monolayers formed at the solid/water (bottom monolayer) and air/water interface (top monolayer) in water (no calcium was added) is shown. The dimensions in the figure are in units of Å and are based on Rodriguez-Loureiro et al. (13). To see this figure in color, go online.