# Peer Review Publications

Liron Bitan-Cherbakovsky, Dima Libster, Abraham Aserin, and Nissim. Garti. 2011. “Complex Dendrimer-Lyotropic Liquid Crystalline Systems: Structural Behavior and Interactions.” Journal of Physical Chemistry B, 115, 42, Pp. 11984–11992. Abstract
The incorporation of dendrimer into three lyotropic liq. cryst. (LLCs) mesophases is demonstrated for the first time. A second generation (G2) of poly(propylene imine) dendrimer (PPI) was solubilized into lamellar, diamond reverse cubic, and reverse hexagonal LLCs composed of glycerol monooleate (GMO), and water (and D-$\alpha$-tocopherol in the HII system). The combination of PPI with LLCs may provide an advantageous drug delivery system. Cross-polarized light microscope, small-angle X-ray scattering (SAXS), and attenuated total reflectance Fourier transform IR (ATR-FTIR) were utilized to study the structural behavior of the mesophases, the localization of PPI within the system, and the interactions between the guest mol. and the system's components. It was revealed that PPI-G2 functioned as a "water pump", competing with the lipid headgroups for water binding. As a result, L$\alpha$→HII and Q224→HII structural shifts were detected (at 10 wt % PPI-G2 content), probably caused by the dehydration of monoolein headgroups and subsequent increase of the lipid's crit. packing parameter (CPP). In the case of HII, as a result of the balance between the dehydration of the monoolein headgroups and the significant presence of PPI within the interfacial region, increasing the quantity of hydrogen bonds, no structural transitions occurred. ATR-FTIR anal. demonstrated a downward shift of the H-O-H (water), as a result of PPI-G2 embedment, suggesting an increase in the mean water-water H-bond angle resulting from binding PPI-G2 to the water network. Addnl., the GMO hydroxyl groups at $\beta$- and $\gamma$-C-OH positions revealed a partial interaction of hydrogen bonds with N-H functional groups of the protonated PPI-G2. Other GMO interfacial functional groups were shown to interact with the PPI-G2, in parallel with the GMO dehydration phenomenon. In the future, these outcomes can be used to design advanced drug delivery systems, allowing administration of dendrimers as a therapeutic agent from LLCs. [on SciFinder(R)]
Marganit Cohen-Avrahami, Dima Libster, Abraham Aserin, and Nissim. Garti. 2011. “Sodium Diclofenac and Cell-Penetrating Peptides Embedded in HII Mesophases: Physical Characterization and Delivery.” Journal of Physical Chemistry B, 115, 34, Pp. 10189–10197. Abstract
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)]
Rivka Deutch-Kolevzon, Abraham Aserin, and Nissim. Garti. 2011. “Synergistic cosolubilization of omega-3 fatty acid esters and CoQ10 in dilutable microemulsions.” Chemistry and Physics of Lipids, 164, 7, Pp. 654–663. Abstract
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)]
Janna Gurfinkel, Abraham Aserin, and Nissim Garti. 2011. “Interactions of surfactants in nonionic/anionic reverse hexagonal mesophases and solubilization of alpha-chymotrypsinogen A.” COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 392, 1, Pp. 322–328. Abstract
In an attempt to form H-II mesophases at room temperature we prepared lyotropic liquid crystals with two surfactants of the same lipophilic tails (glycerol monooleate, GMO, and oleyl lactate, OL) but differing in the size and charge of the headgroups. Increasing OL concentration significantly affected the hydration of the headgroups and subsequently the lipids packing. At low OL content the cubic mesophase was formed, while at higher OL contents the formation of hexagonal mesophase was favored. It was assumed that OL competed on the water binding, tuning the headgroups' curvature and the packing parameter inducing the formation of reverse hexagonal mesophase. It was detected that cubic mesophase transformed upon heating to hexagonal structures. The hexagonal mesophases, which were formed both immediately after preparation and after aging, remained stable at elevated temperatures. alpha-Chymotrypsinogen was solubilized into the obtained LLCs at relatively high concentration (up to 1 wt%). The lattice parameter of the host LLCs exhibited a decrease as a function of the protein content. This process was assigned to partial dehydration of the GMO polar moieties in favor to CTA hydration. Generally speaking, the present study indicated that adding anionic to nonionic lipid is highly beneficial to gain additional compositional and structural characteristics of LLCs. (C) 2011 Elsevier B.V. All rights reserved.
Roy Hoffman, Nissim Garti, Abraham Aserin, and Chava. Pemberton. 2011. “Liquid compositions and uses thereof for generating diffusion ordered nmr spectra of mixtures.”. Abstract
Provided are homogeneous liq. systems substantially 1H-NMR inactive and/or devoid of protons and are capable of enhancing the diffusion sepn. of a mixt., the system is substantially devoid of at least one NMR active nucleus present in the mixt. Further provided are methods of using the homogeneous liq. systems for enhancing the diffusion sepn. of a mixt. and/or generating a diffusion ordered spectrum of a mixt. and/or minimizing the peak width in a liq. state diffusion ordered spectrum of a mixt. [on SciFinder(R)]
Dima Libster, Abraham Aserin, and Nissim. Garti. 2011. “Interactions of biomacromolecules with reverse hexagonal liquid crystals: Drug delivery and crystallization applications.” Journal of Colloid and Interface Science, 356, 2, Pp. 375–386. Abstract
A review. Recently, self-assembled lyotropic liq. crystals (LLCs) of lipids and water have attracted the attention of both scientific and applied research communities, due to their remarkable structural complexity and practical potential in diverse applications. The phase behavior of mixts. of glycerol monooleate (monoolein, GMO) was particularly well studied due to the potential utilization of these systems in drug delivery systems, food products, and encapsulation and crystn. of proteins. Among the studied lyotropic mesophases, reverse hexagonal LLC (HII) of monoolein/water were not widely subjected to practical applications since these were stable only at elevated temps. Lately, we obtained stable HII mesophases at room temp. by incorporating triacylglycerol (TAG) mols. into the GMO/water mixts. and explored the phys. properties of these structures. The present feature article summarizes recent systematic efforts in our lab. to utilize the HII mesophases for solubilization, and potential release and crystn. of biomacromols. Such a concept was demonstrated in the case of two therapeutic peptides-cyclosporin A (CSA) and desmopressin, as well as RALA peptide, which is a model skin penetration enhancer, and eventually a larger macromol.-lysozyme (LSZ). In the course of the study we tried to elucidate relationships between the different levels of organization of LLCs (from the microstructural level, through mesoscale, to macroscopic level) and find feasible correlations between them. Since the structural properties of the mesophase systems are a key factor in drug release applications, we investigated the effects of these guest mols. on their conformations and the way these mols. partition within the domains of the mesophases. The examd. HII mesophases exhibited great potential as transdermal delivery vehicles for bioactive peptides, enabling tuning the release properties according to their chem. compn. and phys. properties. Furthermore, we showed a promising opportunity for crystn. of CSA and LSZ in single crystal form as model biomacromols. for crystallog. structure detn. The main outcomes of our research demonstrated that control of the phys. properties of hexagonal LLC on different length scales is key for rational design of these systems as delivery vehicles and crystn. medium for biomacromols. [on SciFinder(R)]
Tehila Mishraki, Maria Francesca Ottaviani, Alexander I Shames, Abraham Aserin, and Nissim. Garti. 2011. “Structural Effects of Insulin-Loading into HII Mesophases Monitored by Electron Paramagnetic Resonance (EPR), Small Angle X-ray Spectroscopy (SAXS), and Attenuated Total Reflection Fourier Transform Spectroscopy (ATR-FTIR).” Journal of Physical Chemistry B, 115, 25, Pp. 8054–8062. Abstract
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)]
Chava Pemberton, Roy Hoffman, Abraham Aserin, and Nissim. Garti. 2011. “New insights into silica-based NMR "chromatography."” Journal of Magnetic Resonance, 208, 2, Pp. 262–269. Abstract
Silica is used as an important component for NMR "chromatog.". In this study the effect of the binding strength to silica of a variety of compds. on their diffusion rate is measured for the first time. Over two orders of magnitude of diffusion difference enhancement was obtained in the presence of silica for some compds. An explanation of the enhancement is given that also allows one to predict the "chromatog." behavior of new compds. or mixts. The binding strength is divided into categories of weakly bound, singly bound and multiply bound. Carboxylates, sulfonates, and diols are found to be particularly strongly bound and to diffuse up to 21/2 orders of magnitude more slowly in the presence of silica. [on SciFinder(R)]
Elena A Mourelatou, Dima Libster, Ido Nir, Sophia Hatziantoniou, Abraham Aserin, Nissim Garti, and Costas. Demetzos. 2011. “Type and Location of Interaction between Hyperbranched Polymers and Liposomes. Relevance to Design of a Potentially Advanced Drug Delivery Nanosystem (aDDnS).” Journal of Physical Chemistry B, 115, 13, Pp. 3400–3408. Abstract
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)]
Chava Pemberton, Roy E Hoffman, Abraham Aserin, and Nissim. Garti. 2011. “NMR Chromatography Using Microemulsion Systems.” Langmuir, 27, 8, Pp. 4497–4504. Abstract
NMR spectroscopy is an excellent tool for structural anal. of pure compds. However, for mixts., it performs poorly because of overlapping signals. Diffusion ordered NMR spectroscopy (DOSY) can be used to sep. the spectra of compds. with widely differing mol. wts., but the sepn. is usually insufficient. NMR chromatog. methods were developed to increase the diffusion sepn. but these usually introduced solids into the NMR sample that reduce resoln. Using nanostructured dispersed media, such as microemulsions, eliminates the need for suspensions of solids and brings NMR chromatog. into the mainstream of NMR anal. techniques. DOSY was used in this study to resolve spectra of mixts. with no increase in line-width as compared to regular solns. Components of a mixt. are differentially dissolved into the sep. phases of the microemulsions. Several examples of previously reported microemulsions and those specifically developed for this purpose were used here. These include a fully dilutable microemulsion, a fluorinated microemulsion, and a fully deuterated microemulsion. Log(diffusion) difference enhancements of up to 1.7 orders of magnitude were obsd. for compds. that have similar diffusion rates in conventional solvents. Examples of com. pharmaceutical drugs were also analyzed via this new technique, and the spectra of up to six components were resolved from one sample. [on SciFinder(R)]
Orit Amsalem, Abraham Aserin, and Nissim. Garti. 2010. “Phospholipids-embedded fully dilutable liquid nanostructures. Part 2: The role of sodium diclofenac.” Colloids and Surfaces, B: Biointerfaces, 81, 2, Pp. 422–429. Abstract
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)]
Ishai Paul Ben, Dima Libster, Abraham Aserin, Nissim Garti, Yuri. Feldman, Paul Ben Ishai, Dima Libster, Abraham Aserin, Nissim Garti, and Yuri. Feldman. 2010. “Influence of Cyclosporine A on Molecular Interactions in Lyotropic Reverse Hexagonal Liquid Crystals.” Journal of Physical Chemistry B, 114, 40, Pp. 12785–12791. Abstract
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)]
Liron Bitan-Cherbakovsky, Idit Yuli-Amar, Abraham Aserin, and Nissim. Garti. 2010. “Solubilization of Vitamin E into HII LLC Mesophase in the Presence and in the Absence of Vitamin C.” Langmuir, 26, 5, Pp. 3648–3653. Abstract
The synergistic solubilization of two major hydrophilic (vitamin C, ascorbic acid, AA) and lipophilic (vitamin E, D-$\alpha$-tocopherol, VE) antioxidants within reverse hexagonal (HII) mesophases is reported. The HII mesophases are composed of monoolein (GMO)/VE/AA/water. A wide range of VE concn. was examd. (on the expense of GMO concns.) while the AA and water concns. remained const. (4 and 12.5 wt %, resp.) in order to expand the HII mesophase. SAXS and DSC combined with ATR-FTIR techniques were utilized to study the interactions between each solubilizate and the HII component that enabled the synergistic accommodation of the hydrophilic and hydrophobic mols. It was revealed that up to 27 wt % VE solubilized within the HII mesophase. This hydrophobic additive localized at the lipophilic GMO tail region solvating the surfactant tails, thereby enabling the formation of the HII structure. As a result, the lattice parameter and the m.p. of the hydrophobic tails decreased. Above 27 wt % VE (up to 33 wt %), once the GMO lipophilic region was homogeneously solvated, addnl. VE mols. located closer to the interface. At this range of concns., new hydrogen bonds between O-H groups of VE and O-H groups of GMO were formed. Once 35 wt % VE was introduced, the HII structure transformed to face-centered reverse micellar cubic phase (Fd3m, Q227). [on SciFinder(R)]
Marganit Cohen-Avrahami, Abraham Aserin, and Nissim. Garti. 2010. “HII mesophase and peptide cell-penetrating enhancers for improved transdermal delivery of sodium diclofenac.” Colloids and Surfaces, B: Biointerfaces, 77, 2, Pp. 131–138. Abstract
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)]