Functional Lyotropic Liquid CrystalMaterials - Liquid Crystalline Functional Assemblies and Their Supramolecular Structures - page 208

5.3
Drug Delivery Using LLC Phases Based on Ionic Surfactants
In contrast to the LLC phases of GMO and (EO) n -O-alkyl surfactants, only
a handful of reports on the study of LLC phases of ionic surfactants for drug
delivery are available. For example, the L, Q II ,andH II phases of the wa-
ter/octanol/dioctyl sodium sulfosuccinate system have been studied for the
transport of water and glucose across human skin [149]. Also, Q II phases of
mixed ionic and uncharged phospholipids in water have been explored for
the sustained in vitro release of timolol maleate, a drug for treatment of glau-
coma [150].
5.4
Drug Delivery via LLC Nanoparticles
There is also a large body of work in the LLC-based drug delivery area that is
based on the use of specific preparation forms or formulations of LLC phases,
rather than on a specific chemical type of surfactant molecule. That is, there
has been a great deal of research into the use of LLC nanoparticles (LLCNPs).
LLCNPs are dispersed submicron-sized particles of LLC phases suspended in
a solvent, that allow for extremely convenient drug delivery applications upon
dispersion or solubilization. Typically, LLCNPs are formed by introducing a li-
quid formulation of the LLC, cosurfactants, and solvent into water to form the
dispersion. However, LLCNPs often have difficulties with respect to fabrica-
tion, formulation, and stabilization with current methods, so a great deal of
research has been devoted to these areas. The majority of drug delivery re-
search with LLCNPs has been focused on the use of LLCNPs of Q II phases,
commonly called “cubosomes” [151-154]. This is because Q II phases have the
potential for high drug loading and good release of hydrophilic drug molecules
as a result of their 3-D interconnected water nanopore structures. The major-
ity of the cubosome systems studied have been based on GMO because of the
prevalence of a Q II phase in its phase diagram. One of the newest innovations
in the LLCNP drug delivery area involves preparation of dry powder precur-
sors of cubosomes [136, 155]. Q-phase LLCNPs have been studied for a wide
range of drug molecules [151-154], including the drug propofol, an anesthetic
currently used in clinical practice in the form of a stable emulsion [156].
5.5
New Directions for LLC Phases in Drug Delivery and Medical Therapy
One very new direction for potential drug or medical therapy with LLC
phases is using them to aid in antibody recognition and binding to func-
tionalized surfaces. A number of commercially available non-charged and
charged surfactants have recently been explored for this purpose [157]. An-