Chemistry Reference
In-Depth Information
CHAPTER 8
Recent Developments in
Lyotropic Liquid Crystals as
Drug Delivery Vehicles
DIMA LIBSTER, ABRAHAM ASERIN, and NISSIM GARTI
Casali Institute of Applied Chemistry, The Institute of Chemistry, The Hebrew University of
Jerusalem, Jerusalem, Israel
Abstract
Recently, self-assembled lyotropic liquid crystals (LLCs) of lipids and water have
attracted the attention of both the scientifi c and the applied research communities due
to the remarkable structural complexity and practical potential of these nanostructures
in diverse applications.
The phase behavior of mixtures of glycerol monooleate (monoolein, GMO) was
particularly well studied due to the potential utilization of these systems in drug deliv-
ery systems, food products, and encapsulation and crystallization of proteins. The
present chapter summarizes structural features of LLCs and recent systematic efforts
to utilize these for solubilization and the potential release of drugs and biomacromol-
ecules. One of the most interesting applications is the implementation of cell-penetrating
peptides in the reversed hexagonal mesophase to enhance the skin-penetrating pattern
of a model drug (sodium diclofenac).
Liquid crystal vehicles were shown to allow “on demand” targeted release, based
on controlling the polymorphism of lyotropic liquid crystalline mesophases. Novel
liquid crystalline matrix-gold nanorod hybrid materials were reported to induce light-
triggered phase transition of liquid crystalline phases. Hydrophobized gold nanorods
(GNRs) have been incorporated within the LLCs, composed of phytantriol and water,
to provide remote heating, and trigger the phase transitions on irradiation at close to
their resonant wavelength. A new pathway to pH-responsive LLCs, enabling the con-
trolled release of hydrophilic drugs diffusing through the water channels of the meso-
phases, was also investigated. The system is capable of self-assembling into a reverse
bicontinuous cubic phase of Im3m symmetry at pH 7 and transforming into a reverse
columnar hexagonal phase at pH 2.
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