Chemistry Reference
In-Depth Information
Lyotropic liquid crystals were shown to entrap several nucleotides into cubic and
lamellar monoolein-based mesophases in order to protect them and enable their
release. Deoxyribonucleic acid (DNA) within two types of reverse columnar hexagonal
mesophases was studied, one based on pure nonionic lipids and the other decorated
by cationic lipids to induce opposite charges at the surfaces of the water channels of
the mesophases. This provided new opportunities in the design technologies for DNA
transfection and for gene delivery.
The main outcomes of the described research demonstrated that control of the
physical properties of hexagonal LLC on different length scales is key for rational
design of these systems as delivery vehicles for both low-molecular-weight therapeutics
and biomacromolecules.
8.1
Introduction
220
8.1.1
Monoolein and Phytantriol: Main Building Blocks of Lipid
Mesophases
222
8.1.2
Cubic Phases
222
8.1.3
Reverse Hexagonal Mesophase as Delivery Vehicles
223
8.2
Phase Behavior
224
8.3
H
II
Mesophase Composed of GMO-Triglyceride-Water as Drug
Delivery Systems
227
8.4
Solubilization and Delivery of Biomacromolecules
235
8.5
“ On Demand ” Lyotropic Liquid Crystal - Based Drug Delivery Systems
242
8.6
Molecular Interactions of Lyotropic Liquid Crystals with Proteins
and Nucleotides
247
8.7
Summary
252
References
252
8.1 INTRODUCTION
Liquid crystals (LCs) are self-assembled organized mesophases with proper-
ties intermediate to those of crystalline solids and isotropic liquids (Gin et al.,
2008). In LC phases, long-range periodicity exists, although the molecules
exhibit a dynamical disorder at atomic distances, as is the case in liquids.
Accordingly, these materials can also be considered ordered fl uids (Larsson,
1989). Lyotropic LCs (LLCs) are materials that are composed from at least
two molecules: an amphiphilic molecule and its solvent. A hydrophilic solvent,
such as water, hydrates the polar moieties of the amphiphiles via hydrogen
bonding, while the fl exible aliphatic tails of the amphiphiles aggregate into
fused hydrophobic regions based on van der Waals interactions. In addition
to morphologic dependence on the chemical composition, LLC are also sensi-
tive to external parameters, such as temperature and pressure (Amar-Yuli,
2008; Gin et al., 2008; Larsson, 1989). As a function of the molecular shape of
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