Vesselin Kolev, Anela Ivanova, Galia Madjarova, Abraham Aserin, and Nissim Garti. 2016. “Unit cell structure of water-filled monoolein in inverted hexagonal mesophase in the presence of incorporated tricaprylin and entrapped lysozyme.” EUROPEAN BIOPHYSICS JOURNAL WITH BIOPHYSICS LETTERS, 45, 2, Pp. 99–112. Abstract
Molecular dynamics (MD) was employed by means of a specific simulation protocol to investigate the equilibrium structure at 25 A degrees C of the hexagonal inverted (H-II) mesophase composed from water, 1-monoolein (GMO), and tricaprylin, with or without entrapped lysozyme. Based on robust and fast MD simulations, the study provides a comprehensive analysis and visualization of the local structure of H-II mesophase containing admixtures. The most important physical insight is the possibility to observe the strong self-recovery capacity of the GMO layer, which allows the H-II mesophase tubes to reorganize and host lysozyme molecules with a size bigger than the diameter of the water channel. This is a direct message to the experimenters that the H-II mesophase has the potential to host molecules larger than the diameter of the water channel. Collective character of the interlipid interactions is outlined, which is not affected by the presence of the cargo and may be the reason for the efficient GMO reorganization. Another important result is the possible explanation of the role of triacylglycerols on the low-temperature stabilization of the H-II mesophase. The analysis shows that despite the low amount of tricaprylin, its molecules prevent the extreme inclination of the lipid tails and thus optimize the alignment capacity of the lipid tails layer. The study also reveals that the packing frustration does not depend on the temperature and the presence of admixtures. Hence, it might be numerically defined as a universal invariant parameter of a stable H-II mesophase composed of a certain lipid.
Nina Lidich, Ellen J Wachtel, Abraham Aserin, and Nissim Garti. 2016. “Water-dilutable microemulsions for transepithelial ocular delivery of riboflavin phosphate.” JOURNAL OF COLLOID AND INTERFACE SCIENCE, 463, Pp. 342–348. Abstract
Riboflavin phosphate (RFP) is an essential compound in the treatment of keratoconus - a degenerative, non-inflammatory disease of the cornea. Currently, the quantitative and efficient transport of riboflavin to the cornea is possible after mechanical removal of the epithelium. To avoid surgical intervention, it is therefore important to develop a method for quantitatively transporting riboflavin across the intact epithelium. In the present study, an RFP-loaded microemulsion was prepared, which could potentially function as an ocular drug delivery system crossing the eye epithelium. The specially designed water-dilutable microemulsion was based on a mixture of nonionic surfactants. Propylene glycol and glycerol acted as cosurfactant and cosolvent assisting in the solubilization of the RFP. The glycerol-rich water-free concentrate consisted of direct micelles for which glycerol served as the hydrophilic phase. In formulations with up to 40 wt% water, the hydrophilic surfactant headgroups and glycerol strongly bind water molecules (DSC and SD-NMR). Above 60 wt% water, globular, O/W nanodroplets, 14 nm in diameter, are formed (SAXS, cryo-TEM, and SD-NMR). The structure of microemulsions loaded with 0.14-4.25 wt% RFP (0.29-8.89 mmol per 100 g formulation) is not significantly influenced by the presence of the RFP. However, in the microemulsions containing 10-80 wt% water, the mobility of RFP in the microemulsion is constrained by strong interactions with the surfactants and cosurfactant, and therefore free transport of the molecule can be achieved only upon higher (\textgreater80 wt%) water dilutions. (C) 2015 Elsevier Inc. All rights reserved.
T Mishraki-Berkowitz, P Ben Ishai, A Aserin, Yu. Feldman, and N Garti. 2015. “The dielectric study of insulin-loaded reverse hexagonal (HII) liquid crystals.” Physical Chemistry Chemical Physics, 17, 14, Pp. 9499–9508. Abstract
The dielec. behavior of the insulin-loaded HII mesophase (contg. GMO-TAG-water-glycerol-insulin) was studied using two empty ref. systems (GMO-TAG-water and GMO-TAG-water-glycerol) at a frequency range of 10-2-106 Hz, and a temp. range of 290-333 K. Three clearly defined relaxation processes were obsd. and assigned to the reorientation of GMO polar heads, the tangential movement of counterions at the interface, and the movements of TAGs through the lipid tail. Upon addn. of glycerol, a heterogeneous inner structure was formed within the HII cylinders: the water-glycerol core surrounded by a water rigid layer. Upon heating, two crit. points were detected referring to the dehydration of the GMO heads (at 304 K, similar to the water-filled HII system) and to energetic modifications (at 316 K), resulting in breaking of the water layer allowing on-demand controlled release. Insulin incorporation combined the features of both ref. HII systems. Yet, unlike the empty HII systems, insulin perturbed the GMO-water interface while decreasing the movement of the GMO headgroup, and reducing T0 (296 K). No interactions were formed between the dipole of each counterion at the interface region and the matrix (the GMO), fitting the Debye process. Dynamic behavior was obsd., pointing to mobility between the hexagonal rods themselves, enabling controlled release from the HII carrier. [on SciFinder(R)]
Laziz Bouzidi, Mark Baker, Nissim Garti, and Suresh S Narine. 2015. “Elucidation of kinetic and symmetry effects on the viscosity and flow behavior of stearic and oleic triacylglycerols.” Journal of the American Oil Chemists' Society, 92, 7, Pp. 939–946. Abstract
The flow behavior and viscosity of TAGs contg. oleic and stearic acids were examd. in the liq. phase as well as at temps. close to the onset of crystn. by means of a temp.-controlled rheometer. Gelling and crystn. transitions were unambiguously identified by singularities in the viscosity vs. temp. curves of the TAGs. An addnl. transition between the gelling and onset of crystn. temps., attributed to the reorganization of the gel, was obsd. in the sym. TAGs only. The effect of the cooling rate, ranging between 0.1 and 5°C/min, was investigated. The flow behavior of the studied TAGs was shown to be strongly detd. by structural parameters (symmetry, degree of unsatn.). The flow behavior was also affected significantly by the cooling rate, suggesting that to certain extents the flow behavior detd. by structural parameters could be changed by manipulating the cooling rate. The study confirmed that TAG crystn. was initiated by and depends, at least in part, on complex mol. short range order transformations occurring in the melt. The findings of the study may be valuable for evaluating systems and equipment that were involved in the storage, handling and processing of materials incorporating these TAGs. [on SciFinder(R)]
My Perlstein, Abraham Aserin, Ellen J Wachtel, and Nissim Garti. 2015. “Propofol solubilization and structural transformations in dilutable microemulsion.” COLLOIDS AND SURFACES B-BIOINTERFACES, 136, Pp. 282–290. Abstract
Propofol (2,6-diisopropylphenol) is a drug for both induction and maintenance of anesthesia. Pure propofol cannot be injected because of its lipophilic character, low water-solubility, and low bioavailability. Presently, propofol is formulated in an unstable emulsion, easily oxidized, and easily contaminated with bacteria. We are proposing new, propofol-loaded modified microemulsions, stable thermodynamically, and microbiologically safe; the microemulsions are fully dilutable with water. Structural characterization of the empty and the propofol-loaded systems as a function of water dilution was accomplished using advanced analytical tools such as SD-NMR, SAXS, cryo-TEM, DSC, electrical conductivity, and viscosity. Upon water dilution the propofol-loaded concentrate forms swollen reverse micelles that upon further dilution (40 wt% water) progressively transform into a bicontinuous mesophase and then invert (\textgreater65 wt% water) into O/W nanodroplets without ``losing\''\ the solubilized propofol. The drug exhibits strong interactions with the surfactant (DSC and SD-NMR). Propofol increases the size of the microemulsion nanodroplets, but does not modify the microemulsion behavior. Water, ethanol, and PG are essential structural components, but do not interact directly with propofol. (C) 2015 Published by Elsevier B.V.
Yael Cegla-Nemirovsky, Abraham Aserin, and Nissim Garti. 2015. “Oleogels from Glycerol-Based Lyotropic Liquid Crystals: Phase Diagrams and Structural Characterization.” In JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY, 92: Pp. 439–447. Abstract
In the course of our studies on structured reverse lyotropic liquid crystals (LLC) as oleogels, a system was designed with the desired physical and rheology properties for cosmetic and pharmaceutical applications. The aqueous phase was partially replaced by glycerol to minimize bacteriological problems and obtain specific rheology characteristics. The constructed phase diagrams are based on ternary mixtures of glycerol monooleate (GMO), decane, water, and glycerol. The main lyotropic mesophase obtained in this study was reverse hexagonal derived from dilution line 8:2 (72 wt% GMO and 18 wt% decane) and 10 wt% water; or water:glycerol (wt ratios 3:1 and 1:1) mixture. It was found that heat-cool fluctuation caused formation of new pseudo-equilibrium structures with mesomorphic transformations to more fluid and less ordered mesostructures. Replacing up to 50 wt% of the water by glycerol significantly increases the gel phase region in the phase diagram, meaning more structural compositional options. The structural parameters were determined using cross-polarized light microscopy (CPLM), differential scanning calorimeter (DSC), powder X-ray diffraction (PXRD), and small angle X-ray scattering (SAXS). Rheological measurements revealed viscoelastic properties of lyotropic liquid crystals with a decrease in the elasticity (G'), plasticity (GaEuro(3)), and complex viscosity (eta\*\), as a function of increasing the glycerol content.
Marganit Cohen-Avrahami, Alexander I Shames, Francesca M Ottaviani, Abraham Aserin, and Nissim. Garti. 2014. “On the correlation between the structure of lyotropic carriers and the delivery profiles of two common NSAIDs.” Colloids and Surfaces, B: Biointerfaces, 122, Pp. 231–240. Abstract
Two non-steroidal anti-inflammatory drugs (NSAIDs), sodium diclofenac (Na-DFC) and celecoxib (CLXB) were solubilized within cubic and lamellar mesophases as carriers for transdermal drug delivery. SD-NMR, SAXS, ATR-FTIR, and EPR measurements were performed to examine the systems' characteristics and the interactions between the drugs and their hosting mesophases. The amphiphilic drug Na-DFC was found to incorporate at the interfaces of the cubic and lamellar mesophases and thus to act as a cosurfactant and a "structure stabilizer". It increased the order degree and the interactions between the GMO mols. and led the systems toward denser packing. CLXB exhibits an opposite effect on the mesophases. Its solubilization within both systems is accompanied with significant channel swelling and decrease in the order degree. The hydrophobic, rigid and bulky CLXB behaves as a "structure breaker", incorporated between the GMO tails, disturbing the mesophase packing and enhancing the repulsion at the tails region, limiting their close binding. Release expts. from Franz cells revealed that Na-DFC release is dependent on the quantity of water within the hosting mesophase as the water-rich formulation exhibits 1.5-fold enhancement in the release of the drug, compared to the lamellar phase. In contrast, CLXB release was not influenced by the water quantity, hinting that the release mechanisms of the drugs are different while Na-DFC diffuses from the water channels to the external phase, CLXB diffusion occurs through the continuous lipophilic region. The difference in the solubilization sites and interactions of each drug with the mesophases affect their release profiles and det. the preferred formulations for each drug's delivery vehicle. [on SciFinder(R)]
Marganit Cohen-Avrahami, Alexander I Shames, Francesca M Ottaviani, Abraham Aserin, and Nissim. Garti. 2014. “HIV-TAT Enhances the Transdermal Delivery of NSAID Drugs from Liquid Crystalline Mesophases.” Journal of Physical Chemistry B, 118, 23, Pp. 6277–6287. Abstract
Sodium diclofenac (Na-DFC) and celecoxib (CLXB) are common nonsteroidal anti-inflammatory (NSAID) drugs which suffer from poor bioavailability and severe side effects when consumed orally, and their transdermal delivery might present important advantages. In this study, the drugs were solubilized in cubic and lamellar mesophases as transdermal delivery vehicles, and a cell-penetrating peptide, HIV-TAT (TAT), was examd. as a skin penetration enhancer. SD-NMR, ATR-FTIR, and EPR measurements revealed that, in the cubic mesophase (which is rich in water content), TAT populates the aq. cores and binds water, while in the dense lamellar system (with the lower water content) TAT is bound also to the glycerol monooleate (GMO) and increases the microviscosity and the order degree. TAT secondary structure in the cubic system was found to be a random coil while once it was embedded in the closely packed lamellar system it transforms to a more ordered compact state of $\beta$-turns arranged around the GMO headgroups. TAT remarkably increased the diffusion of Na-DFC and CLXB from the cubic systems by 6- and 9-fold enhancement, resp. TAT effect on drug diffusion from the lamellar systems was limited to an increase of 1.3- and 1.7-fold, resp. The dense packing and strong binding in the lamellar phase led to slow diffusion rates and slower drug release in controlled pattern. These effects of the chem. compn. and vehicle geometry on drug diffusion are demonstrated with the impacts of TAT which can be specifically utilized for controlling skin delivery of drugs as required. [on SciFinder(R)]
Mark R Baker, Laziz Bouzidi, Nissim Garti, and Suresh S Narine. 2014. “Multi-Length-Scale Elucidation of Kinetic and Symmetry Effects on the Behavior of Stearic and Oleic TAG. II: OSO and SOO.” JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY, 91, 10, Pp. 1685–1694. Abstract
The phase composition of triacylglycerols (TAG) is determined by chemical structure and is greatly affected by kinetics. Positional isomerism and unsaturation are two key structural elements that govern, for a large part, the phase behavior of TAG during crystallization. Polymorphism, thermal properties, and microstructure of dioleoyl-stearoyl isomers (OSO, SOO) were investigated at different cooling rates with XRD, DSC and PLM techniques, respectively. The physical properties of the symmetrical TAG were found to predictably vary with cooling rate; whereas, the properties of the asymmetrical TAG remained relatively constant. This was explained to be mainly due to the extra steric hindrance caused by asymmetry and the disturbances introduced at the ``terrace\''\ level via methyl-end group interactions. The findings underscore the intricate contribution of saturation and symmetry to the phase trajectories of diunsaturated TAG. The knowledge gained will help understand the behavior of more complex materials and can be used for the manipulation of fat structures at different length scales and direct the manufacture of novel food systems and other relevant materials.
Alon Elyada, Nissim Garti, and Helga. Furedi-Milhofer. 2014. “Polyelectrolyte Multilayer-Calcium Phosphate Composite Coatings for Metal Implants.” Biomacromolecules, 15, 10, Pp. 3511–3521. Abstract
The prepn. of org.-inorg. composite coatings with the purpose to increase the bioactivity of bioinert metal implants was investigated. As substrates, glass plates and rough titanium surfaces (Ti-SLA) were employed. The method comprises the deposition of polyelectrolyte multilayers (PEMLs) followed by immersion of the coated substrate into a calcifying soln. of low supersatn. (MCS). Single or mixed PEMLs were constructed from poly-L-lysine (PLL) alternating with poly-L-glutamate, (PGA), poly-L-aspartate (PAA), and/or chondroitin sulfate (CS). ATR-FTIR spectra reveal that (PLL/PGA)10 multilayers and mixed multilayers with a (PLL/PGA)5 base contain intermol. $\beta$-sheet structures, which are absent in pure (PLL/PAA)10 and (PLL/CS)10 assemblies. All PEML coatings had a grainy topog. with aggregate sizes and size distributions increasing in the order: (PLL/PGA)n \textless (PLL/PAA)n \textless (PLL/CS)n. In mixed multilayers with a (PLL/PGA)n base and a (PLL/PAA)n or (PLL/CS)n top, the aggregate sizes were greatly reduced. The PEMLs promoted calcium phosphate nucleation and early crystal growth, the intensity of the effect depending on the compn. of the terminal layer(s) of the polymer. In contrast, crystal morphol. and structure depended on the supersatn., pH, and ionic strength of the MCS, rather than on the compn. of the org. matrix. Crystals grown on both uncoated and coated substrates were mostly platelets of calcium deficient carbonate apatite, with the Ca/P ratio depending on the pptn. conditions. [on SciFinder(R)]
Liron Bitan-Cherbakovsky, Dima Libster, Dietmar Appelhans, Brigitte Voit, Abraham Aserin, and Nissim. Garti. 2014. “Reversed Hexagonal Lyotropic Liquid-Crystal and Open-Shell Glycodendrimers as Potential Vehicles for Sustained Release of Sodium Diclofenac.” Journal of Physical Chemistry B, 118, 14, Pp. 4016–4024. Abstract
The effect of second, third, and fifth generations of poly(propylene imine) glycodendrimers-open maltose shell (PPI-Mal) on reverse hexagonal (HII) mesophase and on the release of sodium diclofenac (Na-DFC) drug was investigated. The HII mesophase comprised glycerol monooleate (GMO)/tricaprylin (TAG) in a wt. ratio of 90/10 and 20 wt. % water (+0.5 wt. % PPI-Mal of each generation) without or with 0.25 wt. % (Na-DFC). The microstructural characteristics of these systems were detd. by small-angle X-ray scattering; attenuated total reflectance Fourier transform IR was used to characterize the mol. level interactions and the location of the PPI-Mal. Third-and fifth-generation PPI-Mal, because of their maltose groups, interact mainly with the bulk water within the cylinders of the HII and strongly bind the water mols., as manifested by the decrease in the lattice parameter and dehydration of the lipid headgroups. Co-solubilization of Na-DFC with the third and fifth generations caused competition of the two host compds. for water binding and induced relocation of the drug from the bulk water to the GMO-water interface. In vitro release of Na-DFC from the HII showed that the release process was faster in the systems with third- and fifth-generation PPI-Mal compared with the control and second-generation systems. [on SciFinder(R)]
Nissim Garti, Dima Libster, and Abraham Aserin. 2014. “Solubilization and Delivery of Drugs from GMO-Based Lyotropic Liquid Crystals.” In NANOSCIENCE WITH LIQUID CRYSTALS: FROM SELF-ORGANIZED NANOSTRUCTURES TO APPLICATIONS, edited by Q Li, Pp. 355–414. Abstract
Self-assembled lyotropic liquid crystals (LLCs) of lipids and water are interesting mesophases that can be considered among other applications as delivery vehicles due to their remarkable structural complexity. The phase behavior of mixtures of glycerol monooleate (monoolein, GMO) and phytantriol were particularly well studied in drug delivery systems, food products, and encapsulation and crystallization of proteins. We are summarizing in this chapter our contribution to modified LLCs and their structural features and recent systematic efforts to utilize them for solubilization, and potential release of drugs and biomacromolecules. Some of the most interesting applications are the implementation of peptides and proteins in the reversed cubic and hexagonal mesophases, to enhance penetrating pattern of a model drugs. LLC vehicles were shown to allow ``on demand'' targeted release, based on controlling the polymorphism of lyotropic liquid crystalline mesophases. A new pathway to responsive LLCs, enabling the controlled release of hydrophilic drugs diffusing through the water channels of the mesophases was also investigated. The system is capable of self-assembling into a reverse bicontinuous cubic phase of Im3m symmetry and transform into a reverse columnar hexagonal as a function of pH, pressure or enzymes. LLCs were shown to entrap several peptides enzymes, proteins and nucleotides into cubic and lamellar monoolein-based mesophases in order to protect them and enable their release. 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.
Liron Bitan-Cherbakovsky, Abraham Aserin, and Nissim. Garti. 2014. “The effect of dendrimer generations on the structure of QG LLC mesophase and drug release.” Colloids and Surfaces, B: Biointerfaces, 122, Pp. 30–37. Abstract
In this paper the cosolubilization of 2nd, 3rd, and 4th generations of polypropyleneimine (PPI: PPI-G2, -G3, and -G4) dendrimers with sodium diclofenac (Na-DFC) into reverse gyroid cubic (QG) liq. crystals is reported. Structural properties and interactions of PPI dendrimers with and without the drug were studied using small-angle X-ray scattering, attenuated total reflected Fourier transform IR (ATR-FTIR) spectroscopy, and differential scanning calorimetry (DSC) measurements. Incorporation of PPI-G2 (without Na-DFC) into QG mesophase led to a decrease of 78 \AA in the lattice parameter. Solubilization of higher PPI generations, G3 and G4, led to increases in the lattice parameter to 57 \AA and 64 \AA, resp. At 25 wt%, each of the dendrimers caused a phase transition QG → reverse hexagonal (HII). According to ATR-FTIR and DSC, the large lattice parameter values of G3 and G4 (relative to G2) embedment were assigned to their interactions with the carboxyl groups of GMO at the interface in comparison to the strong interaction of PPI-G2 with the water. Cosolubilization of Na-DFC with PPI-G2 revealed enlargement of the lattice parameter (of the new HII mesophase), while in the case of G3 and G4 systems no significant influence was seen with Na-DFC. The release of Na-DFC from QG and HII systems was followed by UV-vis spectroscopy and revealed generation-dependence on drug release. As dendrimer generation increased, the cumulative drug release decreased. [on SciFinder(R)]
Vesselin L Kolev, Anela N Ivanova, Galia K Madjarova, Abraham Aserin, and Nissim. Garti. 2014. “Unit Cell Structure of Water-Filled Monoolein into Inverted Hexagonal (HII) Mesophase Modeled by Molecular Dynamics.” Journal of Physical Chemistry B, 118, 20, Pp. 5459–5470. Abstract
The study investigates the unit cell structure of inverted hexagonal (HII) mesophase composed of monoolein (1-monoolein, GMO) and water using atomistic mol. dynamics methods without imposing any restraints on lipid and water mols. Statistically meaningful and very contrast images of the radial mass d. distribution, scrutinizing also the sep. components water, monoolein, the polar headgroups of the lipids, the double bond, and the termini of the hydrocarbon chain (the tail), are obtained. The lipid/water interface structure is analyzed based on the obtained water d. distribution, on the estd. no. of hydrogen bonds per monoolein headgroup, and on the headgroup-water radial distribution functions. The headgroup mass d. distribution demonstrates hexagonal shape of the monoolein/water interface that is well-defined at higher water/monoolein ratios. Water interacts with the headgroups by forming a three-layer diffusive mass d. distribution, and each layer's shape is close to hexagonal, which is an indication of long-range structural interactions. It is found that the monoolein headgroups form a const. no. of hydrogen bonds leaving an excessive amt. of water mols. outside the first lipid coordination sphere. Furthermore, the quantity of water at the monoolein/water interface increases steadily upon extension of the unit cell, so the interface should have a very dynamic structure. Investigation of the hydrocarbon residues reveals high compression and well-expressed structuring of the tails. The tails form a very compressed and constrained structure of defined layers across the unit cell with properties corresponding to a more densely packed nonpolar liq. (oil). Due to the hexagonal shape the 2D packing frustration is const. and does not depend on the water content. All reported structural features are based on averaging of the at. coordinates over the time-length of the simulation trajectories. That kind of processing allows the observation of the water/GMO interface shape and its stability and mobility at a time scale close to the ones of the intermol. interactions. [on SciFinder(R)]
MF Ottaviani, D Appelhans, Javier F de la Mata, S Garcia-Gallego, A Fattori, C Coppola, M Cangiotti, L Fiorani, JP Majoral, AM Caminade, M Bryszewska, DK Smith, N Garti, and B Klajnert. 2013. “Characterization of dendrimers and their interactions with biomolecules for medical use by means of electron magnetic resonance.” In Dendrimers Biomed. Appl., Pp. 115–133. Royal Society of Chemistry. Abstract
In the first part of this study, a computer aided EPR anal. was performed to intensively study the Cu(II) complexation behavior of different dendrimers: (a) a series of PPI dendrimers ranging up to the fifth generation that had either a dense maltose or maltotriose shell; (b) sulfonated or carboxylated carbosilane dendrimers; (c) self-assembling amine- terminated dendrons. The Cu(II) coordination and symmetry of the generated complexes depend on the dendrimer chem. structure, the functionalization in the periphery, dendrimer generation and the ratio of the copper and dendrimer concns. As generation increased, the glycodendrimers showed (a) increased nitrogen coordination in a axial symmetry, due to the increased no. of nitrogen sites in the dendrimer interior, and (b) a rhombic structure which forms in the congested dendrimer periphery where the sugar units are also able to coordinate the copper ions. [on SciFinder(R)]
Nissim Garti, Dima Libster, Liron Bitan-Cherbachovsky, and Abraham. Aserin. 2013. “Dendrimer-lyotropic liquid crystal systems for drug delivery.”. Abstract
This invention relates to novel complex dendrimer-lyotropic liq. crystal systems for drug delivery,. A second generation polypropylenimine dendrimer was solubilized into lamellar, diamond reverse cubic and reverse hexagonal lyotropic mesophases composed of glycerol monooleate and water. [on SciFinder(R)]
Tehila Mishraki, Paul Ben Ishai, Dmitry Babukh, Abraham Aserin, Yuri Feldman, and Nissim. Garti. 2013. “Modulation of physical properties of reverse hexagonal mesophases: A dielectric spectroscopy study.” Journal of Colloid and Interface Science, 396, Pp. 178–186. Abstract
The structural, dynamic, and kinetic aspects of the HII systems based on glycerol monooleate (GMO), phosphatidylcholine (PC), triacylglycerol (TAG), and water were investigated by dielec. spectroscopy in a frequency range of 10-2-106 Hz, and a temp. range of 290-320 K. Three distinct processes as well as a temp.-activated dc cond. were detected and examd. These were assigned to the reorientation of the GMO polar heads, the tangential movement of counterions at the interface, the transport of TAGs through the lipids tails, and the ion mobility within the water cylinders. Upon addn. of PC, the crit. temp. (T0) of the dehydration of the GMO headgroups increased. The optimal concn. found for structural stabilization of the HII mesophase was 10 wt% PC, since it imparted the strongest bonding at the interfacial layer and increased the assocn. between the lipid tails. Within the HII cluster, TAG percolated and shifted between the hexagonal rods themselves. The present study demonstrated the benefit of controlling the crit. temp. of the HII mesophase partial dehydration and softening, as well as the percolation of TAGs. These factors influence the diffusion mode of embedded drugs in the physiol. temp. range. [on SciFinder(R)]
K Gardikis, EA Mourelatou, M Ionov, A Aserin, D Libster, B Klajnert, M Bryszewska, N Garti, J.-P. Majoral, K Dimas, and C Demetzos. 2013. “Natural and synthetic biomaterials as composites of advanced drug delivery nano systems (ADDNSS). Biomedical applications.” In Dendrimers Biomed. Appl., Pp. 30–39. Royal Society of Chemistry. Abstract
A review. This article reviews the creation of advanced drug delivery nano systems (aDDnSs) comprised of liposomes and polymers focusing on the interactions of the structural components and their biomedical applications. ADDnSs have been shown to significantly: (a) increase the load of the bioactive substance into the system, which is very important both for manufg.-economic reasons and for toxicity reasons (as less quantity of carrier is used for the same amt. of drug), (b) lower the release rate of the encapsulate drug, a fact that could create a more controlled and/or sustained release profile of the drug in the bloodstream, leading to lower toxicity and higher effectiveness (c) advanced pharmacol. toxicity compared to the free drug and at least equal toxicity compared to the resp. conventional liposomal formulation. A plethora of physicochem. data has begun to shed light to the interactions of the components of these complicate systems that seem to be responsible for the advantages presented by the aDDnSs. [on SciFinder(R)]
Meital Aviv-Gavriel, Nissim Garti, and Helga. Furedi-Milhofer. 2013. “Preparation of a Partially Calcified Gelatin Membrane as a Model for a Soft-to-Hard Tissue Interface.” Langmuir, 29, 2, Pp. 683–689. Abstract
Cartilage and/or bone tissue engineering is a very challenging area in modern medicine. Since cartilage is an avascular tissue with limited capacity for self-repair, using scaffolds provides a promising option for the repair of severe cartilage damage caused by trauma, age-related degeneration, and/or diseases. Our aim in this study was to design a model for a functional biomedical membrane to form the interface between a cartilage-forming scaffold and bone. To realize such a membrane gelatin gels contg. calcium or phosphate ions were exposed from one side to a soln. of the other constituent ion (i.e., a sodium phosphate soln. was allowed to diffuse into a calcium-contg. gel and vice versa). The partially calcified gels were analyzed by XRD, ATR-FTIR spectra, E-SEM, and EDX. Thus, we confirmed the existence of a gradient of crystals, with a dense top layer, extending several micrometers into the gel. XRD spectra and Ca/P at. ratios confirmed the existence of calcium deficient apatites. The effect of different exptl. parameters on the calcification process within the gelatin membranes has been elucidated. It was shown that increasing the gelatin concn. from 5 wt % to 10 wt. % retards calcification. A similar effect was obsd. when glycerol, which is frequently used as plasticizer, was added to the system. With increasing calcium concn. within the org. matrix, the quantity and d. of calcium phosphate crystals over/within the gel increased. The possible explanations for the above phenomena are discussed. [on SciFinder(R)]
Laziz Bouzidi, Tolibjon S Omonov, Nissim Garti, and Suresh S Narine. 2013. “Relationships between molecular structure and kinetic and thermodynamic controls in lipid systems. Part I: propensity for oil loss of saturated triacylglycerols.” Food & Function, 4, 1, Pp. 130–143. Abstract
Pure satd. triacylglycerols (TAGs) in canola oil were used as model systems to analyze oil loss in structured oil both from thermodn. and kinetic perspectives. Two important parameters which effectively and predictively measure the relative propensity of a solid network to lose/hold oil were defined: (1) the rate of oil loss, K, which is a quantified representation of the kinetics of oil loss and (2) the initial amt. of oil susceptible to be lost, i.e., the propensity for oil loss (POL), which is a representation of the thermodn. of oil binding. It was found that the POL and K values do not always trend in the same fashion, suggesting that the mechanism of oil binding is complex, depending on the structurant's cryst. form locked within the oil network. The two parameters were, however, correlated to the melting and thermal behavior of the structurants, to the polymorphic structures that are obtained during the cooling process and to the habit (shape, size and morphol.) of the cryst. phase in the oil. Both POL and K had a strong correlation to the oil loss. [on SciFinder(R)]