Glycerol monooleate (GMO)-based mesophases offer extensive prospects for incorporation of various bioactive mols. This work deals with the solubilization of selected cell-penetrating peptides (CPPs) together with sodium diclofenac (Na-DFC) within the HII mesophase for transdermal applications. The effect of CPPs such as RALA (an amphipathic CPP), penetratin (PEN), and oligoarginine (NONA) on Na-DFC skin permeation kinetics to provide controlled release and tune the drug transdermal diffusion was studied. The location of the drug and the CPPs within the mesophase was probed by DSC and FTIR. Na-DFC was found to be located at the interfacial region between the surfactant chains, leading to denser HII mesophase. The hydrophilic NONA was intercalated into the aq. cylinders and caused their swelling. It induced a significant decrease in the hydrogen binding between the GMO carbonyls and their surrounding. The amphiphilic PEN was entrapped within two different regions, depending on its concn. PEN and NONA improved Na-DFC permeation by 100%, whereas RALA enhanced permeation by 50%. When estg. Na-DFC migration rate out of the mesophase toward surrounding aq. media, it appeared to be slower with the CPPs. The peptides were not involved at this diffusion-controlled step. It seems that their effect on skin permeation is based on their specific interaction with the skin. [on SciFinder(R)]

In the present work, we report on the solubilization of gabapentin (GBP) into lyotropic hexagonal mesophases composed of monoolein, tricaprylin, and water. It was demonstrated that the hexagonal structure remained intact up to 2 wt. % gabapentin, whereas the lamellar phase coexisted with the hexagonal one in the concn. range of 3-4 wt. % of the drug. At gabapentin content of 5-6 wt. %, only lamellar phases contg. defects such as dislocations and multilamellar vesicles were detected. Incorporation of GBP decreased the lattice parameter of the HII mesophase from 56.6 to 50.6 \AA, while the structural dimensions of the lamellar phase were not affected. ATR-FTIR anal. suggested enhanced hydrogen bonding between the protonated amine of GBP and the O-H groups of the GMO and the water surrounding in the inner hydrophilic interface region. This led to intercalation of the drug into the water-lipid interface. At higher GBP loads of 4-6 wt. %, thermal anal. revealed disordering within the lipid packing, apparently induced by the spatially altered interface area. Rheol. measurements correlated the macroscopic features of the systems with alterations on the mol. level and allowed distinguishing between closely related mesophases due to their different rheol. characteristics. In vitro transdermal delivery studies showed that the examd. mesophases enabled a sustained release of GBP compared to its aq. soln. Sustained release was more pronounced in the case of the hexagonal mesophase, compared to the lamellar one. [on SciFinder(R)]

This review is dedicated to the memory of Professor Kunieda Hironobu and his Fundamental scientific contribution in the study of lyotropic liq. crystals. It displays an assortment of studies from his research group describing unique liq.-cryst. systems and novel phases.which represent their contribution to this topic. Finally, modern studies focusing on the formation of novel and modified structures on the basis of nonionic surfactant, monoolein, are discussed. [on SciFinder(R)]

Chapters 1 and 11

Insulin entrapment within a monoolein-based reverse hexagonal (HII) mesophase was investigated under temp.-dependent conditions at acidic (pH 3) and basic (pH 8) conditions. Studying the structure of the host HII system and the interactions of insulin under temp.-dependent conditions has great impact on the enhancement of its thermal stabilization and controlled release for the purposes of transdermal delivery. Small angle X-ray spectroscopy (SAXS) measurements show that pH variation and/or insulin entrapment preserve the hexagonal structure and do not influence the lattice parameter. Attenuated total reflection Fourier transform spectroscopy (ATR-FTIR) spectra indicate that, although insulin interacts with hydroxyl groups of GMO in the interface region, it is not affected by pH variations. Hence different microenvironments within the HII mesophase were monitored by a computer-aided ESR anal. using 5-doxylstearic acid (5-DSA) as a pH-dependent probe. The microviscosity, micropolarity, order of systems, and distribution of the probes in different microenvironments were influenced by three factors: temp., pH, and insulin solubilization. When the temp. is increased, microviscosity and order parameters decreased at both pH 3 and 8, presenting different decrease trends. It was found that, at pH 3, the protein perturbs the lipid structure while "pushing aside" the un-ionized 5-DSA probe to fit into the narrow water cylinders. At the interface region (pH 8), the probe was distributed in two differently structured environments that significantly modifies by increasing temp. Insulin loading within the HII mesophase decreased the order and microviscosity of both the microenvironments and increased their micropolarity. Finally, the EPR anal. also provides information about the unfolding/denaturation of insulin within the channel at high temps. [on SciFinder(R)]

Water-dilutable microemulsions were prepd. and loaded with two types of omega-3 fatty acid esters (omega-3 Et esters, OEE; and omega-3 triacylglycerides, OTG), each sep. and together with ubiquinone (CoQ10). The microemulsions showed high and synergistic loading capabilities. The linear fatty acid ester (OEE) solubilization capacity was greater than that of the bulky and robust OTG. The location of the guest mols. within the microemulsions at any diln. point were detd. by elec. cond., viscosity, DSC, SAXS, cryo-TEM, SD-NMR, and DLS. We found that OEE mols. pack well within the surfactant tails to form reverse micelles that gradually, upon water diln., invert into bicontinuous phase and finally into O/W droplets. The CoQ10 increases the stabilization and solubilization of the omega-3 fatty acid esters because it functions as a kosmotropic agent in the micellar system. The hydrophobic and bulky OTG mol. strongly interferes with the tail packing and spaces them significantly - mainly in the low and medium range water dilns. When added to the micellar system, CoQ10 forms some reverse hexagonal mesophases. The inversion into direct micelles is more difficult in comparison to the OEE system and requires addnl. water diln. The OTG with or without CoQ10 destabilizes the structures and decreases the solubilization capacity since it acts as a chaotropic agent to the micellar system and as a kosmotropic agent to hexagonal packing. These results explain the differences in the behavior of these mols. with vehicles that solubilize them in aq. phases. Temp. disorders the bicontinuous structures and reduces the supersatn. of the system contg. OEE with CoQ10; as a result CoQ10 crystn. is retarded. [on SciFinder(R)]

Advanced drug delivery nanosystems (aDDnSs) combining liposomal and dendritic materials have only recently appeared in the research field of drug delivery. The nature and localization of the interactions between the components of such systems are not yet fully described. In this study, liposomes are combined with hyperbranched polyesters for the development of new aDDnSs. The polymer-lipid interactions along with their dependence on the polyesters pseudogeneration no. and the liposomal lipid compn. have been examd. The results indicate that the interaction between the materials takes place in the headgroup region, where H-bonds between the polymers terminal hydroxyls and the phospholipids phosphate moiety are formed. Due to the polymers' compact imperfect structure, which varies with pseudogeneration no., no linear trends are obsd. with increasing pseudogeneration no. Moreover, it is shown that high percentages of cholesterol in the lipid bilayer affect the penetration of the polymers in the headgroup region. [on SciFinder(R)]

In this communication we demonstrate for the first time that lyotropic reverse hexagonal mesophase can serve as a crystn. medium for a hydrophobic peptide, resulting in high quality single crystals suitable for crystallog. anal. The obtained crystals of cyclosporin A enabled excellent X-ray data collection, diffracting to a resoln. limit of 1.0 \AA. Current findings open a new perspective in the field of crystn. of biol. macromols. in lyotropic mesophases. [on SciFinder(R)]

Using microemulsions (ME) as delivery vehicles requires understanding whether water-insol. mols. are delivered by an interaction of the ME system with the dietary mixed micelles (DMM) in the small intestine to give new mixed micelles, or by alternate paths. Dild. DMM and ME systems were mixed at various wt. ratios to address this question. The individual and mixed systems were characterized by phys. techniques that address this interaction from different aspects. This research showed that increased DMM concn. in ME/DMM mixed systems caused: (1) increased conformational order of the acyl chains and perturbed hydrogen bonds between the ethoxylate headgroups (based on ATR-FTIR results); (2) significant increase in microviscosity (from 1.7 to 3.3 ns) (based on EPR results); (3) increased diffusivity of the surfactant mols. compared to their diffusivity in pure ME droplets, and decreased diffusivity of the taurochenodeoxycholate mols. compared to their diffusivities in pure DMM micelles (based on PGSE-NMR results); (4) formation or modification of intramol. interactions (based on NOESY-NMR results); (5) decreased av. droplet diam. and increased droplet d. per unit area compared to pure ME systems (based on DLS and cryo-TEM results); and (6) fluorescence resonance energy transfer between two dyes (diphenylhexatriene and Nile Red), which were solubilized in each system sep. (based on fluorescence resonance energy transfer results). These results show that DMM and ME interact to create ME-DMM mixed micelles, providing a potential pathway for delivering solubilized mols. [on SciFinder(R)]

Cloudy emulsions are oil-in-water (O/W) emulsions normally prepd. as concs., further dild., per request, into the final beverage. The cloudy emulsion provides flavor, color, and cloud (turbidity) to the soft drink. These systems are stabilized by emulsifiers and/or amphiphilic polysaccharides. Cloudy emulsions based on naturally occurring food grade emulsifiers were studied in the present work. Two charged natural biopolymers, whey protein isolate (WPI) and gum arabic (GA), are interacted in aq. soln. to form charge-charge interactions improving the emulsion stability. The emulsions were high sheared (Microfluidizer) and characterized by particle size distribution anal. (DLS), optical centrifugation (LUMiFuge), optical microscopy observations, and turbidity measurements. Emulsions obtained from 10 wt% of 3:1 wt. ratio WPI:GA, at pH 7 (10 wt% canola oil) show better stability than emulsions stabilized by GA or WPI alone. The droplet sizes were smaller than 1 $μ$m and did not grow significantly during 1 mo of incubation at 25 °C. The D-limonene-based emulsion droplets were larger (\textgreater2 $μ$m) than those made with vegetable oils immediately after prepn. and underwent significant droplet size increase (coalescence) within 1 mo (\textgreater8 $μ$m). The emulsion with turbidity suitable as a cloudy emulsion was composed of 3 wt% WPI:GA (3:1) and 20 wt% canola oil. [on SciFinder(R)]

This study develops a novel transdermal delivery vehicle for the enhanced delivery of sodium diclofenac (Na-DFC). The system utilizes the advantages of reversed hexagonal lyotropic liq. crystals (HIILC), combined with a peptide cell penetration enhancer (CPE), creating together an adaptable system that provides versatile options in the field of transdermal delivery. This enhancer peptide is based on a family of amphipathic peptides that exhibit improved membrane permeability. Franz permeation cell expts. revealed that the peptide enhancer (RALA) improved Na-DFC skin penetration of the liq. crystal 2.2-fold. The authors studied the structural effects of RALA solubilization on the HII mesophase. RALA acts as a chaotropic agent, interfering in the structure of the water, and causes a measurable swelling of the aq. cylinders by 5 \AA. Small angle x-ray scattering (SAXS) and attenuated total reflectance-Fourier transform IR (ATR-FTIR) measurements reveal enhanced hydration of the glycerol monooleate (GMO) headgroups and a 6.5% increase in the fraction of non-freezable water resulting from RALA incorporation. RALA caused a gradual increase in the GMO effective headgroup area due to the hydration, leading eventually to a transform of the hexagonal structure towards a lamellar one. CD and ATR-FTIR measurements showed a conservation of the peptide structure when incorporated into the HII mesophase. The combined HIILC-CPE systems can serve as high potential vehicles for a variety of drugs, as they can easily be modified by varying the compn. and temp., according to the required dose and delivery features. [on SciFinder(R)]

In this paper the authors examd. feasible correlations between the structure of different lyotropic mesophases and transdermal administration of three diclofenac derivs. with varying degrees of kosmotropic or chaotropic properties, solubilized within the mesophases. It was found that the most chaotropic deriv. of diclofenac di-Et amine (DEA-DFC) interacted with the polar heads of glycerol monooleate (GMO), thus expanding the water-lipid interface of the lamellar and cubic mesophases. This effect was detected by an increase in the lattice parameter of both mesophases, enhanced elastic properties, and increased solid-like response of the systems in the presence of DEA. Potassium diclofenac (K-DFC), a less chaotropic salt, had less pronounced effect on the structural features of the mesophases. Kosmotropic Na+ salt (Na-DFC) had only minor influence on both lamellar and cubic structures. The locus of solubilization of the mols. with the host mesophases was correlated with their delivery. It was suggested that transdermal delivery of kosmotropic Na-DFC was accelerated by the aq. phase and less constrained by the interaction with monoglyceride. The chaotropic cations (K+ and DEA+), presumably entrapped in the water-lipid interface, interacted with monoglyceride headgroups, which is likely to be the key cause for their sustained administration. [on SciFinder(R)]

We present a dielectric study of H(II) mesophases (H(II)) based on a GMO/tricaprylin/phosphatidylcholine/water system seeded with the peptide Cyclosporine A (CSA). The study covers a frequency range 0.01 Hz to 1 MHz and a temperature range of 293 to 319 K, with a 3 K temperature step. Three dielectric relaxation processes are observed and discussed. This picture is further elucidated by comparison with a dielectric study of the empty H(II) mesophase system, previously published, where the same three processes were involved. A complex picture emerges whereby the CSA is intercalated between the surfactant tails yet protrudes into the interface as well. Whereas the CSA remains hydrophobic, it still influences the relaxation behavior of the GMO head and counterion movement along the interface in a nontrivial manner. The third dipolar species, the tricaprylin molecule, is also influenced by the presence of CSA. A critical temperature T(0) = 307 K is recognized and identified as the dehydration temperature of the surfactant heads. This induces a conformal transition in the CSA, drastically changing its effect on the three dielectric processes evident in the raw data. The implications of this behavior are discussed in detail.[on SciFinder (R)]

In this study we have attempted to understand the nature of "charge interactions" between two neg. charged biopolymers (whey protein isolate, WPI and gum Arabic, GA) and, consequently, why their mixt. exhibits better interfacial activity. Surface tension ($\gamma$0) measurements indicated that at ca. 1 wt.% of the biopolymer mixt. (3:1 wt. ratio) the air/water surface is satd. At 5 wt.% the $\gamma$0 of the mixt. is lower than the calcd. co-operative value. The $\zeta$-potential measurements revealed that the isoelec. point of the WPI:GA 3:1 wt. ratio mixt. is 3.8. The $\zeta$-potential values up to pH 6 are below those calcd. Similarly, the elec. conductivities of the mixt. are lower than those calcd. All these measurements indicate: (1) partial charge neutralization in spite of the fact that both biopolymers are neg. or (2) partial charge-charge interactions between the two biopolymers. The thermal heating behavior of the frozen water in the aq. mixt. studied by DSC (heating cycle of the frozen sample) clearly indicates that the two biopolymers are interacting. We calcd. the enthalpy, the free energy and the chem. potential of the interactions. We found that the interactions of the biopolymers are rather weak. They are likely derived from some local pos. charged domains (pH 7) on the protein that neutralize some of the neg. charged GA. These interactions form weak charge adducts. These charge adducts are sufficient to improve its adsorption into the oil-water interface and enhance the emulsion stability. [on SciFinder(R)]

A model protein (lysozyme) was incorporated into monoolein-based reverse hexagonal (HII) mesophase and its structure effects were characterized by small angle X-ray scattering, ATR-FTIR spectroscopy, and rheol. measurements. Modifications in mol. organization of the HII mesophases as well as the conformational stability of lysozyme (LSZ) as a function of pH and denaturing agent (urea) were clarified. Up to 3 wt. % LSZ can be solubilized into the HII. The vibration FTIR anal. revealed that LSZ interacted with OH groups of glycerol monooleate (GMO) in the outer interface region, resulting in strong hydrogen bonding between the surfactant and its environment. Simultaneously, the decrease in the hydrogen-bonded carbonyl population of GMO was monitored, indicating dehydration of the monoolein carbonyls. These mol. interactions yielded a minor decrease in the lattice parameter of the systems, as detected by small angle X-ray scattering. Furthermore, LSZ was crystd. within the medium of the hexagonal structures in a single crystal form. The $\alpha$-helix conformation of lysozyme was stabilized at high pH conditions, demonstrating greater helical structure content, compared to D2O soln. Moreover, the hexagonal phase decreased the unfavorable $\alpha$ → $\beta$ transition in lysozyme, thereby increasing the stability of the protein under chem. denaturation. The rheol. behavior of the hexagonal structures varied with the incorporation of LSZ, reflected in stronger elastic properties and pronounced solid-like response of the systems. The hydrogen bonding enhancement in the interface region of the structures was most likely responsible for these phenomena. The results of this study provided valuable information on the use of hexagonal systems as a carrier for incorporation and stabilization of proteins for various applications. [on SciFinder(R)]

We prepd. and investigated cubic bicontinuous (V) phase from mixts. of nonionic monoolein (GMO) and anionic oleyl lactate (OL) surfactants in the presence of ethanol and water. The isotropic region and the compn. of the V phase in the pseudoternary phase diagram vary with the nature of the hydrophilic headgroups and their charge. We examd. three anionic species, acidic (HOL), partially neutralized (OL), and totally ionized (NaOL) forms. The largest swollen V region within the phase diagram was formed from the partially neutralized form. The V formation is dependent on the GMO/OL ratio. The largest isotropic region in the phase diagrams was found with GMO/OL at a 70:30 wt % ratio and in the presence of 5.0 and 38.5 wt % ethanol and water, resp. The structural effect of OL was detd. by small-angle X-ray spectroscopy, differential scanning calorimetry, and Fourier transform IR. The results revealed that the structure is curvature-dependent. Mesophases made from 90:10 wt % GMO/OL showed phase transition from gyroid (G) to diamond (D) symmetry. Prepns. made from 30:70 wt % GMO/OL exhibited coexistence of two mesophases, one (of low order) cubic and the other lamellar. Because of the overall gauche deformation growth, the hydrocarbon order decreased with the OL content increase. The GMO, sn2 and sn3 headgroups, and water structure vibration bands indicate a chaotropic effect as a result of the interdigitation of OL anions and Na+ and H+ counterions. [on SciFinder(R)]

Complex pseudo-ternary phase diagrams based on sucrose monolaurate (SE), propylene glycol (PG), and phosphatidylcholine (PC) as the "surfactant phase"; triacetin (TA) and decaglycerol ester (10G1CC) as the "oil phase"; and water as the aq. phase were constructed, into which the authors solubilized the water-insol. drug (sodium diclofenac, Na-DFC). In the authors' previous study the authors demonstrated that the solubilization of Na-DFC in the oil + surfactant phases (prior to dilg. it with water), was 90-fold greater than its dissoln. in water, and that the system was pH-dependent. The greatest Na-DFC solubilization capacity was obtained at pH 7.2. In this study the authors examd. the effect of the solubilization of Na-DFC in a phosphatidylcholine system using DLS, viscosity, elec. cond., SAXS, SD-NMR, and cryo-TEM measurements. It was found that: (1) the system remains micellar after aq. diln. but with greater polydispersity and greater variety of shapes. The authors concluded that the structures in the absence of water (but in the presence of PG) were of direct spherical micelles (∼4 nm) mixed with elongated cylindrical micelles (12-140 nm); (2) the aq. diln. causes fragmentation of the cylinders into smaller spherical micelles; (3) solubilization of Na-DFC behaving like a kosmotropic agent or "structure maker" yields mostly spherical swollen micelles and more ordered systems than in its absence; and (4) Na-DFC is solubilized at the interface of the micelles without swelling the droplets. [on SciFinder(R)]

The present work investigates, for the first time, a system comprising a dendrimer incorporated into the water core of water-in-oil (W/O) microemulsion (ME). A second generation (G-2) poly(propyleneimine) dendrimer (PPI) was solubilized into W/O ME composed of AOT (sodium bis(2-ethylhexyl)sulfosuccinate), heptane, and water. Such a model system possessing the benefits of both dendrimers and ME, can potentially offer superior control of drug administration. The localization of PPI within the system, its specific interactions with the components of the carrier, and its effect on the ME structure was explored by SAXS, DSC, ATR-FTIR, and elec. cond. measurements. Considerable water binding by PPI, accompanied by partial dehydration of AOT polar heads, was detected by ATR-FTIR and DSC anal., suggesting that PPI acted as a "water pump". In addn., SAXS measurements showed periodicity increase and disordering of the droplets. Hence, localization of PPI within the core and interfacial regions of the droplets was assumed. Direct electrostatic interactions between PPI and the sulfonate group were not noticed, since the dendrimer mols. were mostly not protonated in the current basic environment at pH 12. However, slight hydrogen bonding between PPI and the S=O groups allowed the dendrimer to behave as a "spacer" between sodium and sulfonate ions. This affected the elec. cond. behavior of the system, revealing that PPI favored the percolation process. Most likely, PPI decreased the rigidity of the interfacial layer, facilitating the diffusion of sodium ions through the channels. The characterized model system can be advantageously utilized to design specific delivery vehicles, allowing administration of dendrimers as a therapeutic agent from host MEs. [on SciFinder(R)]