Chapter 3 - Properties of multifunctional bionanomaterials of lipid A-phosphate in liquid phases and quasi-crystalline structures

Abstract

Lipid A-diphosphate is associated with lethal endotoxicity, specific immune responses, and plays a key role during infection with microorganisms or viruses. Periodic self-assembled lipid A-diphosphate structures were investigated by light scattering, small-angle X-ray scattering (SAXS) in aqueous dispersions, transmission electron microscopy (TEM), and small-area electron diffraction. SAXS experiments are consistent with equilibrium phase structures that appear as crystal variants of dodecahedra and icosahedra depending on lipid A-phosphate composition. The lipid A-diphosphate form factors were also calculated by nonlinear parameters using an efficient Bayesian parameter estimation. The phases for the lipid A-diphosphate and their mixture components show 12-fold or sixfold diffraction symmetry. The two-dimensional (2D) cross-sectional diffraction patterns are consistent with (6.6.6), (4.6.12), and (3.3.4.3.4) Archimedean tiling. Changes of the ratio of the lipid A-diphosphate variants in the quasicrystal are accompanied with a change of the ratio of the equilateral triangles and squares in the unit cells. The predominant 2D tiling structures are the honeycomb-type structure with a tiling pattern, where each hexagonal domain contacts the other six domains.