Margulis-Goshen K, Kamyshny A, S.Magdassi
. Application of surfactants in pharmaceutical dosage forms
. In: Zoller U
Handbook of Detergents- Part E: Applications. Taylor & Francis ; 2009.
Margulis-Goshen K, Kamyshny A, Magdassi S
. Applications of surfactants in pharmaceutical dosage forms.
Surfactant Sci. Ser.Surfactant Science Series. 2009;141 (Handbook of Detergents, Part E) :455 - 468.Abstract
A review. The use of surfactants in oral, parenteral, and other delivery systems is described as well as their role as active agents (e.g. spermicides). [on SciFinder(R)]
Grouchko M, Popov I, Uvarov V, Magdassi S, Kamyshny A
. Coalescence of Silver Nanoparticles at Room Temperature: Unusual Crystal Structure Transformation and Dendrite Formation Induced by Self-Assembly.
LangmuirLangmuir. 2009;25 (4) :2501 - 2503.Abstract
It was found that during the evapn. of water from a droplet of a silver nanoparticles dispersion a self-assembly process leads to the coalescence of the nanoparticles at room temp. and eventually results in a 3D, micrometer-sized dendrite. Direct in situ HR-TEM observation of coalescence events of individual nanoparticles revealed that during this process a transformation of the nanoparticles' crystal structure takes place, from the common fcc silver structure to the unusual hcp structure. It was found that even-though a majority of the nanoparticles in the dispersion have the fcc structure the obtained dendrites are characterized by the hcp structure, reflecting the crystal structure transformation due to the coalescence process. [on SciFinder(R)]
Levin KB, Dym O, Albeck S, Magdassi S, Keeble AH, Kleanthous C, Tawfik DS
. Following evolutionary paths to protein-protein interactions with high affinity and selectivity.
Nat. Struct. Mol. Biol.Nature Structural & Molecular Biology. 2009;16 (10) :1049 - 1055.Abstract
How do intricate multi-residue features such as protein-protein interfaces evolve. To address this question, we evolved a new colicin-immunity binding interaction. We started with Im9, which inhibits its cognate DNase ColE9 at 10-14 M affinity, and evolved it toward ColE7, which it inhibits promiscuously (Kd > 10-8 M). Iterative rounds of random mutagenesis and selection toward higher affinity for ColE7, and selectivity (against ColE9 inhibition), led to an ∼105-fold increase in affinity and a 108-fold increase in selectivity. Anal. of intermediates along the evolved variants revealed that changes in the binding configuration of the Im protein uncovered a latent set of interactions, thus providing the key to the rapid divergence of new Im7 variants. Overall, protein-protein interfaces seem to share the evolvability features of enzymes, i.e., the exploitation of promiscuous interactions and alternative binding configurations via 'generalist' intermediates, and the key role of compensatory stabilizing mutations in facilitating the divergence of new functions. [on SciFinder(R)]
Grouchko M, Kamyshny A, Magdassi S
. Formation of air-stable copper-silver core-shell nanoparticles for ink-jet printing.
J. Mater. Chem.Journal of Materials Chemistry. 2009;19 (19) :3057 - 3062.Abstract
Copper nanoparticles can be utilized as a low-cost replacement for silver and gold nanoparticles which are currently used in ink-jet printing of conductive patterns. However, the main obstacle for using copper nanoparticles is their spontaneous oxidn. at ambient conditions. Here the authors describe the synthesis of nonoxidizable copper nanoparticles by coating them with a silver shell, and ink-jet printing of these particles. The formation of these core-shell nanoparticles is driven by a transmetalation reaction on the surface of copper nanoparticles, where the copper atoms present on the particles' surface are used as the reducing agent for the silver. This process results in formation of solely copper-silver core-shell nanoparticles, with no individual silver particles. It was found that coating 40 nm copper nanoparticles with a 2 nm layer of silver prevents oxidn. of the copper core and preserves its metallic characteristic. Characterization of these nanoparticles by HR-TEM, SEM, EDS, XRD, spectrophotometry and XPS confirm the core-shell structure and their stability to oxidn. Ink-jet printing of concd. aq. dispersions of these copper-silver nanoparticles was done on various substrates, and it was found that conductive and decorative patterns with metallic appearance, stable to oxidn. (up to 150°) are formed. [on SciFinder(R)]
Generalova AN, Sizova SV, Oleinikov VA, Zubov VP, Artemyev MV, Spernath L, Kamyshny A, Magdassi S
. Highly fluorescent ethyl cellulose nanoparticles containing embedded semiconductor nanocrystals.
Colloids Surf., AColloids and Surfaces, A: Physicochemical and Engineering Aspects. 2009;342 (1-3) :59 - 64.Abstract
Highly luminescent org. nanoparticles were formed by embedding hydrophobic and hydrophilic (CdSe)ZnS quantum dots with core/shell structure into Et cellulose nanoparticles. The nanoparticles were prepd. from oil-in-water nanoemulsions by a phase inversion process at const. temp., followed by a solvent evapn. The obtained fluorescent Et cellulose nanoparticles were functionalized by immobilization of a specific antibody, and applied in rapid agglutination test for detection of Yersinia pestis F1-antigen. [on SciFinder(R)]
Magdassi S, Grouchko M, Kamyshny A
.; 2009. Methods of producing core-shell metallic nanoparticles and ink compositions containing same.Abstract
A compn. including a plurality of multi-metallic nanoparticles each consisting essentially of a core comprising at least one first metal (Me1) and a continuous shell comprising atoms of at least one second metal (Me2). Optionally, the continuous shell of Me2 atoms protects the Me1 atoms from oxidn. at all temps. ≤150°. The reducing agent includes: hydrazine hydrate, sodium borohydride, sodium formaldehydesulfoxilate (Rongalite), ascorbic acid and sodium ascorbate. The water sol. polymer is a polyelectrolyte including polyacrylic acid, polyacrylic acid sodium salt,polycarboxylatethers, polyimine, polydiallyldimethylammonium chloride, polyvinylpyrrolidone, proteins and polypyrrole, polysaccharides. Said Me2 salt comprises: silver, gold, palladium and platinum. Said Me1 comprises: zinc, copper, nickel, cobalt and iron. [on SciFinder(R)]
Nizri G, Makarsky A, Magdassi S, Talmon Y
. Nanostructures Formed by Self-Assembly of Negatively Charged Polymer and Cationic Surfactants.
LangmuirLangmuir. 2009;25 (4) :1980 - 1985.Abstract
The formation of nanoparticles by interaction of an anionic polyelectrolyte, sodium polyacrylate (NaPA), was studied with a series of oppositely charged surfactants with different chain lengths, alkyltrimethylammonium bromide (CnTAB). The binding and formation of nanoparticles was characterized by dynamic light scattering, ζ-potential, and self-diffusion NMR. The inner nanostructure of the particles was obsd. by direct-imaging cryogenic-temp. transmission electron microscopy (cryo-TEM), indicating aggregates of hexagonal liq. crystal with nanometric size. [on SciFinder(R)]
Spernath L, Regev O, Levi-Kalisman Y, Magdassi S
. Phase transitions in O/W lauryl acrylate emulsions during phase inversion, studied by light microscopy and cryo-TEM.
Colloids Surf., AColloids and Surfaces, A: Physicochemical and Engineering Aspects. 2009;332 (1) :19 - 25.Abstract
Phase changes during the prepn. of nano-emulsions contg. polymerizable monomer as the oil phase, by the phase inversion temp. technique (PIT), were investigated using light microscopy, cryo-TEM and viscosity measurements. The nano-emulsions were prepd. using a poly(oxyethylene) nonionic surfactant and a polymerizable acrylic monomer (lauryl acrylate) as the oil phase. Inversion of the emulsion, followed by rapid cooling, resulted in emulsions having an av. droplet size as low as 25 nm. Cryo-TEM was used to observe the structures that are present above and below the phase transition temp., and gave, for the first time, visual indication of the presence of a microemulsion and a locally ordered structure in the process. At high surfactant concns., the inversion-cooling process yields emulsions with unique structures, in which the oil phase is present as worm-like structures. [on SciFinder(R)]
Grouchko M, Kamyshny A, Ben-Ami K, Magdassi S
. Synthesis of copper nanoparticles catalyzed by pre-formed silver nanoparticles.
J. Nanopart. Res.Journal of Nanoparticle Research. 2009;11 (3) :713 - 716.Abstract
Synthesis of well dispersed copper nanoparticles was achieved by redn. of copper nitrate in aq. soln. using hydrazine monohydrate as a reducer in the presence of preformed silver nanoparticles as catalysts. It has been demonstrated that addn. of silver nanoparticles to the reaction mixt. leads to formation of aq. dispersion of copper nanoparticles and also results in a drastic redn. in reaction time compared to procedures reported in the literature. The absorption spectrum of the dispersions, HR-TEM, and STEM images and XRD pattern indicate the formation of copper nanoparticles with particle size in the range of 5-50 nm. [on SciFinder(R)]
Margulis-Goshen K, Magdassi S
. Formation of simvastatin nanoparticles from microemulsion
. In: Nanomedicine Nanomedicine : nanotechnology, biology, and medicine. Vol. 5. ; 2009. pp. 274 - 81.Abstract
UNLABELLED: The present study evaluates a new method to prepare nanoparticles of a poorly water-soluble drug, simvastatin, by evaporation of all solvents from spontaneously formed oil-in-water microemulsions. By this method, microemulsions containing a volatile solvent as an oil phase are converted into nanoparticles in the form of dry non-oily flakes by freeze-drying. The presence of simvastatin in nanoparticles was determined by dispersing the flakes in water and subsequent filtering through a 0.1-microm filter, followed by measuring the simvastatin concentration in the filtrate. It was found that after freeze-drying more than 95% of the drug was present in amorphous particles, smaller than 100 nm. It was found that tablets containing the flakes of simvastatin nanoparticles showed tremendous enhancement in dissolution profile compared with conventional tablets. X-ray diffraction revealed that in the resulting flakes simvastatin nanoparticles were initially amorphous, but a slow crystallization process took place when the product was stored at room temperature. FROM THE CLINICAL EDITOR: This paper describes a new method to prepare nanoparticles of a poorly water-soluble drug, simvastatin, by evaporation of all solvents from spontaneously formed oil-in-water microemulsions. Tablets containing the flakes of simvastatin nanoparticles showed tremendous enhancement in dissolution profile compared with conventional tablets.[on SciFinder (R)]
Layani M, Gruchko M, Milo O, Balberg I, Azulay D, Magdassi S
. Transparent conductive coatings by printing coffee ring arrays obtained at room temperature
. ACS NanoACS Nano. 2009;3 (11) :3537 - 3542.Abstract
We report here a concept for utilization of the "coffee ring effect" and inkjet printing to obtain transparent conductive patterns, which can replace the widely used transparent conductive oxides, such as ITO. The transparent conductive coating is achieved by forming a 2-D array of interconnected metallic rings. The rim of the individual rings is less than 10 μm in width and less than 300 nm in height, surrounding a "hole" with a diam. of about 150 μm; therefore the whole array of the interconnected rings is almost invisible to the naked eye. The rims of the rings are composed of self-assembled, closely packed silver nanoparticles, which make the individual rings and the resulting array elec. conductive. The resulting arrays of rings have a transparency of 95%; resistivity of 0.5 cm2 was 4 ± 0.5 Ω/☐, which is better than conventional ITO transparent thin films. The silver rings and arrays are fabricated by a very simple, low cost process, based on inkjet printing of a dispersion of 0.5 wt % silver nanoparticles (∼20 nm diam.) on plastic substrates. The performance of this transparent conductive coating was demonstrated by using it as an electrode for a plastic electroluminescent device, demonstrating the applicability of this concept in plastics electronics. It is expected that such transparent conductive coatings can be used in a wide range of applications such as displays (LCD, plasma, touch screens, e-paper), lighting devices (electroluminescence, OLED), and solar cells. [on SciFinder(R)]