Chemistry Reference
In-Depth Information
Chapter 6
Synergistic Solubilization of Mixed
Nutraceuticals in Modified Discontinuous
Micellar Cubic Structures
Rivka Efrat, Abraham Aserin and Nissim Garti
CASALI INSTITUTE OF APPLIED CHEMISTRY, INSTITUTE OF
CHEMISTRY, THE HEBREW UNIVERSITY OF JERUSALEM,
JERUSALEM 91904, ISRAEL
6.1 Introduction
Lyotropic liquid crystals are known to self-assemble in lamellar, hexagonal
and cubic symmetries. These are mostly bicontinuous, but they can become
discontinuous in certain cases and under specific conditions.
1
Several symme-
tries of cubic phases have been described in the literature. A discontinuous
cubic structure with space group of Pm3n (Q
223
) was first discovered by
Balmbra et al.
2
in 1969 and further studied by Tardieu and Luzzati
3
in a
variety of lipid + water systems. The space group of Fd3m (Q
227
) was first
described by Tardieu
4
and observed in a variety of lipid + water systems, in all
of which the lipid was heterogeneous.
5-11
The space group of P4
3
32 (Q
212
) has,
so far, been reported in a system composed of protein + lipid + water, as in
monoolein + cytochrome C + water.
12,13
The space group Fm3n (Q
225
) was first
observed in a surfactant + water system
13
and later in several ganglioside +
water systems.
14
Once the domain of a liquid crystalline phase becomes discontinuous,
micellar systems with similar structures can be formed. Only a few reports
have dealt with the discontinuous structures and all of them are related to cubic
symmetries. Micellar discontinuous cubic phases are composed of discrete
aggregates (micelles) ordered in a three-dimensional array.
1,7
These structures
have been recognized as a separate and unique form of a micellar solution.
Topologically, micellar cubic systems can be structured as discrete aggregates
of well-organized oil-in-water (type I) micelles or inverse water-in-oil (type II)
micelles.
1,12
Recently, we detected
15,16
a new and modified organization of a self-assem-
bled discontinuous micellar cubic phase in systems composed of glycerol
87
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