Self-assembly of Lipid A-phosphates: Supramolecular Liquid Crystals - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 264

Chapter 24
self-assembly of lipid a-phosphates:
supramolecular liquid Crystals
Henrich H. Paradies, Chester A. Faunce, Hendrik Reichelt,
and Kurt Zimmermann
iNtroduCtioN
Self-assembly takes place through both a reversible non-covalent interaction and a
unique recognition involving a variety of building blocks. The components involved
in the formation of two-dimensional (2-D) and three-dimensional (3-D) nano-or µm
scaled periodicities such a cubic, cylindrical, or mesophases are van der Waals and
electrostatic forces, hydrogen bonding as well as p-p stacking forces (Gazit, 2010).
The various observed phases have been investigated extensively for example surfac-
tant water (Seddon, 1996), block copolymers (Matsen and Bates, 1996), and ther-
motropic materials (Tschierske, 2001). Lyotropic materials can provide templates for
porous inorganic materials (Attard et al., 1997) and lyotropics such as double chained
N-cationic lipids (Clancy and Paradies, 1997; Clancy et al., 1995). These materials are
also capable of forming complexes with DNA and neutral lipids as well as being use-
ful as carriers in gene therapy and other pharmaceutical formulations (Koltover et al.,
1998; Paradies, 1992; Thies et al., 1996). Other important materials in self-assembly
are dendrons (Rosen et al., 2009) and nanostructural soft matter which show a tapered
shape and account for the formation of bulk phases such as lyotropic materials (Bates
and Fredrickson, 1999) or block copolymers (Anderson et al., 1988). Recently, Ungar
et al. (2003) showed that a self-organized supramolecular dendrimer nanostructure
possessed a noncubic phase and established a relationship between the chemical struc-
ture and the self-assembly composed of tapered dendrons. These materials reveal s
and BCC phases with an increase in temperature. Subsequently, dodecahedral quasi-
crystals were formed, displaying wedge-shaped dendrimer molecules that self-assem-
bled into virtually spherical particles. It was established that each spherical particles
from the branched compounds contained on average 11.6 molecules, on a tetragonal
lattice with 30 particles per unit cell. Similar hierarchical structures, though not identi-
cal, have been found for colloidal crystals of lipid A-phosphates from the bacterial E.
coli source (Faunce and Paradies, 2010). Understanding the characteristics of jammed
lipid A-phosphate packings provides basic insights into the structural arrangements of
lipid A-phosphate liquid crystals and bulk properties of these supramolecular liquid
crystals, glasses, and selected aspects of their biological actions. This contribution
also covers recent advances in understanding jammed packings of polydisperse sphere
mixtures, non-spherical particles for example ellipsoids within the assembly and poly-
hedra for example by “ E.coli Autovaccines ” (Zimmermann et al., 2003)