Publications by Type: Journal Articles

Hai M, Magdassi S. Investigation on the release of fluorescent markers from w/o/w emulsions by fluorescence-activated cell sorter. [Erratum to document cited in CA141:265749]. J. Controlled ReleaseJournal of Controlled Release. 2004;97 (2) :383.Abstract
Some of the results shown in Figures 1, 2, 4a, and 6 were already reported in Langmuir 20 (2004) 2081-2085. Nevertheless, these earlier results do help in comprehending the full picture of this research project. [on SciFinder(R)]
Hai M, Magdassi S. Investigation on the release of fluorescent markers from w/o/w emulsions by fluorescence-activated cell sorter. J. Controlled ReleaseJournal of Controlled Release. 2004;96 (3) :393 - 402.Abstract
The mechanism of release of two fluorescent markers, fluorescein isothiocyanate-bovine serum albumin (FITC-BSA) and fluorescein, from water-in-oil-in-water (w/o/w) emulsions was investigated using a rapid and sensitive method based on fluorescence-activated cell sorting (FACS). The release of FITC-BSA from a w/o/w emulsion was controlled by diffusion rather than by simple breakdown of the multiple droplets or by formation of reverse micelles in the oil phase. In contrast, the release of fluorescein from a double emulsion was controlled by formation of reverse micelles rather than by diffusion or simple breakdown of multiple droplets. A significant difference in the yield and fraction of FITC-BSA and fluorescein released from double emulsions was obsd. due to their different mol. structure and properties. The yield of FITC-BSA incorporation in a double emulsion increased with increasing FITC-BSA concn. in the internal water phase, while the yield of fluorescein decreased with increasing concn. The fraction of FITC-BSA released from a w/o/w emulsion after 24 h decreased with an increasing concn. of FITC-BSA in the internal phase. The w/o/w emulsion with internalized FITC-BSA was more stable than that with fluorescein, indicating its further application for sorting or enriching size-controlled double droplets that contained genes and water-sol. drugs. [on SciFinder(R)]
Gorodetsky R, Levdansky L, Vexler A, Shimeliovich I, Kassis I, Ben-Moshe M, Magdassi S, Marx G. Liposome transduction into cells enhanced by haptotactic peptides (Haptides) homologous to fibrinogen C-termini. J. Controlled ReleaseJournal of Controlled Release. 2004;95 (3) :477 - 488.Abstract
Haptides are 19-21mer cell-binding peptides equiv. to sequences on the C-termini of fibrinogen β chain (Cβ), γ chain (preCγ) and the extended αE chain of fibrinogen (CαE). In soln., Haptides accumulated in cells by non-saturable kinetics. This study describes Haptide interactions with liposomes and Haptide-mediated liposome uptake by cells. Haptides became incorporated into neg. charged liposomes, changing their zeta potential. At. force microscopy and particle sizing by light scattering showed that the liposomes dissolved Haptide nanoparticles and absorbed them from soln. Pre-mixing fluorescent rhodamine-contg. liposomes or "stealth" doxorubicin (DOX)-contg. liposomes (Doxil) with Cβ, preCγ or to a lesser degree CαE, significantly enhanced their uptake by fibroblasts and endothelial cells. Confocal microscopy showed Haptide-induced liposome uptake satd. above ∼40 μM Haptide. Cytotoxicity tests with lower concns. of Doxil liposomes indicated that premixing with ∼40 μM Cβ or preCγ increased their toxicity by one order of magnitude. It was evident that the liposomes complexed with an amphiphilic Haptide are transduced through cell membranes, probably by a non-receptor-mediated process. These results suggest that Cβ or pre-Cγ could be employed to augment the cellular uptake of drugs in liposomal formulations. [on SciFinder(R)]
Magdassi S, Ben-Moshe M, Berenstein L, Zaban A. Microemulsion based ink-jet ink: Properties and performance. J. Imaging Sci. Technol.Journal of Imaging Science and Technology. 2003;47 (4) :357 - 360.Abstract
Oil-in-water microemulsions which contain a hydrophobic colorant were evaluated as water based ink-jet inks. These microemulsion based ink-jet inks are thermodynamically stable, have the features of dye based inks prior to printing, and the features of pigment based inks after printing. The microemulsion was prepd. and printed, as described recently by Magdassi et al. using the gemini-type surfactant, didodecyldiphenylether disulfonate, toluene, 1-propanol, water as the continuous phase and Nile Red or Sudan IV as the hydrophobic dye. Microemulsion av. droplet size was measured by dynamic light scattering and found to be ∼8 nm. The authors found by AFM imaging that the printed 20 - 60 μm droplets are composed of nanoparticles with av. size of 130 nm. The printing process was evaluated by a fluorescence microscope, while images of the droplets were viewed as a function of time after impact with the substrate. It was found that the microemulsion droplets formed distorted spheres on ink-jet paper, more perfectly shaped spheres on Forbo paper substrate and perfect round spheres on vinyl slides. When printed on glass, a "bagel like" shape was obtained. The droplet size varied, depending on the surface energy of the substrate, being at least 20 μm for low energy surfaces and growing larger for higher energy substrates. It was noticed that the time scales for spreading on paper was less than tens of milliseconds accompanied and followed by fixation and drying of the droplets in less than 3 - 5 s. [on SciFinder(R)]
Magdassi S, Ben Moshe M, Talmon Y, Danino D. Microemulsions based on anionic gemini surfactant. Colloids Surf., AColloids and Surfaces, A: Physicochemical and Engineering Aspects. 2003;212 (1) :1 - 7.Abstract
Oil in water microemulsions were prepd. using didodecyldiphenylether disulfonate gemini-type surfactant (C12-DADS), water, oil (toluene) and a co-solvent (short chain alc. such as 1-propanol). The phase diagrams for microemulsions with gemini surfactants were detd. and compared to those of structurally related surfactants, monododecyldiphenylether disulfonate (C12-MADS) and monododecyldiphenylether monosulfonate (C12-MAMS). Cond. measurements and direct imaging by cryo-TEM were performed to characterize the phases. [on SciFinder(R)]
Kamyshny A, Relkin P, Lagerge S, Partyka S, Magdassi S. Native and hydrophobized human IgG: enthalpies of heat-induced structural changes and adsorption onto silica. J. Therm. Anal. Calorim.Journal of Thermal Analysis and Calorimetry. 2003;71 (1) :263 - 272.Abstract
Differential scanning calorimetry (DSC) and isothermal calorimetric batch technique were used to monitor the heat-induced structural changes and adsorption properties of human IgG, in native and hydrophobized states. The transition temp. (Tmax) and enthalpy of heat-induced conformational changes (ΔcalH) of IgG in soln. as well as the enthalpy change accompanying the adsorption of IgG onto hydrophilic silica (ΔadsH), were shown to depend on the degree of the protein hydrophobicity (no. of covalently attached alkyl chains). The adsorption enthalpy for all forms of IgG at all surface concns. was found to be endothermic, that is the process is entropy driven. Factors affecting the IgG adsorption onto silica are discussed. [on SciFinder(R)]
Magdassi S, Ben Moshe M. Patterning of Organic Nanoparticles by Ink-jet Printing of Microemulsions. LangmuirLangmuir. 2003;19 (3) :939 - 942.Abstract
Direct ink-jet printing of water-insol. org. materials may provide a new route for low-cost fabrication of various products that require fine patterning of functional mols. However, printing by water-based, environmentally friendly inks requires significant research and development efforts aimed at achieving a dispersion of nanoparticles of the specific mol. in water. We demonstrate a concept for direct patterning of water-insol. org. mols. in the form of nanoparticles, which can be easily adapted to a large variety of mols. such as conducting polymers and org. light-emitting diodes. The method is based on formation of a thermodynamically stable oil-in-water microemulsion in which volatile "oil" droplets contain the dissolved org. mols. The microemulsion droplets are converted into org. nanoparticles upon impact with the substrate surface due to evapn. of the volatile solvent. [on SciFinder(R)]
Cohen E, Joseph T, Kahana F, Magdassi S. Photostabilization of an entomopathogenic fungus using composite clay matrices. Photochem. Photobiol.Photochemistry and Photobiology. 2003;77 (2) :180 - 185.Abstract
To provide photostabilization for entomopathogenic fungi by anionic dyes, composite matrixes based on clay-biopolymer combinations were prepd. In the first step, the neg. surface charge of various clays (montmorillonite, attapulgite, bentonite and kaolinite) was reversed to pos. by adsorption to the polycationic biopolymer chitosan. The second step involved adsorption of the toxicol. safe anionic dyes fast green (FG) and naphthol yellow S (NYS) to the clay complexes. Compared with cytotoxic photoprotectants like berberine, palmatine and acriflavine, the anionic dyes have no adverse effects up to a concn. of 1 M. In assays using various clay-chitosan-dye matrixes and UV irradn. from a lamp source, it was evident that both FG and NYS provided considerable photostabilization for conidia of the entomopathogenic fungus Aschersonia spp. that served as a model biocontrol agent. Because of the light-dispersing property, bentonite and attapulgite per se provided significant photoprotection. All clay matrixes contg. FG provided a substantial photostabilization effect. [on SciFinder(R)]
Izmailova VN, Kamyshny A, Levachev SM, Magdassi S, Kharlov AE, Yampol'skaya GP. Rheological Properties of the Interfacial Layers of Hydrophobized Gelatins. Colloid J.Colloid Journal (Translation of Kolloidnyi Zhurnal). 2003;65 (6) :784 - 785.Abstract
Rheol. properties of the interfacial layers of gelatins chem. modified with N-hydroxysuccinimide ester of caprylic acid (the degree of modification is 10, 30, and 85%) are studied. Interfacial layers are spontaneously formed at the aq. gelatin soln.-toluene interface. Rheol. characteristics (yield strength, modulus of elastic deformation, Schwedoff and Bingham viscosities) increase in proportion to the degree of modification (hydrophobization) of gelatin. [on SciFinder(R)]
Magdassi S, Bassa A, Vinetsky Y, Kamyshny A. Silver Nanoparticles as Pigments for Water-Based Ink-Jet Inks. Chem. Mater.Chemistry of Materials. 2003;15 (11) :2208 - 2217.Abstract
Stabilized concd. citrate-reduced silver nanocolloids for use as pigments in ink-jet inks were prepd. CM-cellulose was used as a polymeric stabilizer providing both electrostatic and steric stabilization. X-ray diffraction pattern, optical properties (UV-visible spectroscopy), size (TEM and dynamic light scattering), and zeta potentials of the nanoparticles were studied. It was shown that the product is silver with cubic symmetry. Absorption spectra are characterized, as a rule, by asym. absorption bands with maxima at 417-440 nm and shoulders at 350-352 and 380-382 nm. TEM images of unstabilized and stabilized colloids indicate the formation of nanoparticles of different shapes (spheres, hexagons, cubes, and rods) with rather wide size distribution in the range from several nanometers (spheres) up to several hundreds of nanometers (rods). CMC was found to be an effective stabilizer of silver nanoparticles, and the av. particle size at CMC concns. from 0.025 to 0.2 wt. % does not exceed 50 nm. Both unstabilized and stabilized silver nanoparticles display neg. zeta potentials in the pH range from 2 to 9; the maximal neg. values are obsd. at pH 6-8 (-27 ± 5 mV for unstabilized and -33 ± 5 mV for CMC-stabilized colloids, resp.). Concd. dispersions of silver nanoparticles (1.1 wt. % of silver), which were stable for at least 7 mo, were prepd. by exhausted lyophilization of the freshly prepd. colloids followed by redispersion. These nanoparticles in the presence of proper wetting agent, such as Disperbyk, can be used as pigments in ink-jet ink formulations for printing on various substrates (paper, glass, and transparencies). The stabilizing agent, CM-cellulose, also acts as a binder, providing good adhesion of ink to the substrates. [on SciFinder(R)]
Kamyshny A, Magdassi S, Avissar Y, Almog J. Water-soaked evidence: detectability of explosive traces after immersion in water. J. Forensic Sci.Journal of Forensic Sciences. 2003;48 (2) :312 - 317.Abstract
Various factors governing the detectability of explosive traces after being soaked in water were studied. The variables are: the type of the surface (surfaces liable to be found in aircraft were chosen), the type of explosive, the type of water (tap or seawater), and movement of the immersed surface in the water. The maximal immersion times (tmax) after which explosive detection was possible were evaluated. This datum was found to depend on the type of explosive (one of the important factors is soly. in water), the surface material and the environmental conditions (tap or seawater movement). Detection of PETN on high-d. polyethylene, linoleum, glass and aluminum, by the chem. Explosive Testing Kit (ETK), was possible even after a month of soaking in seawater. In addn., it was found that movement of bulk water around the samples with deposited explosives considerably decreases tmax values. It is, therefore, recommended to retrieve samples for explosive anal. as soon as possible and in areas where the currents of water is minimal. [on SciFinder(R)]
Lagerge S, Kamyshny A, Magdassi S, Partyka S. Calorimetric methods applied to the investigation of divided systems in colloid science. J. Therm. Anal. Calorim.Journal of Thermal Analysis and Calorimetry. 2003;71 (1) :291 - 310.Abstract
A review. A new batch titrn. microcalorimeter has been used for estn. of thermodn. properties in various investigated colloidal systems. As examples, we present enthalpic and kinetic data obtained from this calorimetric device for four different processes widely encountered in colloid science: (i) the diln./micellization process of cationic gemini surfactants in aq. soln.; (ii) the hydration process of non ionic surfactants in org. soln., i.e. the mechanism of micellar solubilization of water in the aggregates; (iii) the complexation of calcium ions by polyacrylates sodium salts (PaNa); (iv) the adsorption phenomenon of PaNa mols. on the calcium carbonate surface. [on SciFinder(R)]
Izmailova VN, Kamyshny A, Levachev SM, Magdassi S, Kharlov AE, Yampol'skaya GP. Monolayer Parameters of Gelatin Chemically Modified with N-Hydroxysuccinimide Ester of Caprylic Acid. Colloid J.Colloid Journal (Translation of Kolloidnyi Zhurnal). 2002;64 (5) :640 - 642.Abstract
The behavior of gelatin chem. modified with N-hydroxysuccinimide ester of caprylic acid at the aq. (NH4)2SO4 soln.-air interface is studied. The compression isotherms of gelatin monolayers whose pattern is dependent on the degree of gelatin modification are obtained. It is established that the area corresponding to the beginning of isotherm rise, two-dimensional pressure of completely compressed monolayer, and the modulus of monolayer surface elasticity increase with the degree of gelatin hydrophobization. The surface ("adsorption") activity of gelatin with the modification degree of 85% is approx. threefold higher than for the initial gelatin. [on SciFinder(R)]
Kamyshny A, Trofimova D, Magdassi S, Levashov A. Native and modified glucose oxidase in reversed micelles. Colloids Surf., BColloids and Surfaces, B: Biointerfaces. 2002;24 (3-4) :177 - 183.Abstract
The activity of native and modified glucose oxidase (I) from Aspergillus niger in the system of reversed micelles of Aerosol OT (AOT) in octane was investigated. Two forms of modified I were studied: a hydrophobized form obtained by the attachment of palmitic chains to Lys NH2 groups by the reaction with the palmitic acid ester of N-hydroxysuccinimide and a glycosylated (hydrophilized) form obtained by the attachment of cellobiose moieties. Native I and its derivs., while incorporated into micelles in a surfactant concn. range of 0.05-0.3M, displayed enzyme activity which was comparable with the activity in aq. soln. The dependence of enzyme activity on the degree of hydration of the surfactant (the molar ratio of water to surfactant, w0) did not indicate the formation of qual. new assocd. forms of enzyme subunits inside the micelles. The apparent size of AOT micelles obtained by dynamic light scattering gradually increased from 10 nm at low w0 values up to 25 nm at high w0. Incorporation of native and hydrophobized I into the micelles did not affect their mean size. Kinetic anal. showed that enzyme specificity was about an order of magnitude greater in the system of reverse micelles as compared with aq. soln. [on SciFinder(R)]
Kamyshny A, Danino D, Magdassi S, Talmon Y. Transmission Electron Microscopy at Cryogenic Temperatures and Dynamic Light Scattering Studies of Glucose Oxidase Molecules and Self-Aggregated Nanoparticles. LangmuirLangmuir. 2002;18 (8) :3390 - 3391.Abstract
Glucose oxidase (GOx) is the most widely used enzyme in the field of biosensors. GOx catalyzes the oxidn. of β-D-glucose by mol. oxygen to D-glucono-1,4-lactone and hydrogen peroxide and has been used for quant. detn. of glucose in body fluids, foodstuffs, beverages, and fermn. liquor. The efficiency of GOx-based sensors has been limited, primarily as a consequence of heterogeneous enzyme distribution in the biosensor membrane. Attempts to improve the mol. architecture of biosensor films composed of organized layers of membrane lipids and enzyme have utilized the attachment of hydrophobic anchors to the latter. It has been shown previously that hydrophobized GOx displays increased surface activity at the air/water interface as well as an increased ability to penetrate lipid monolayers spread at the same interface. In the present study the complementary techniques of dynamic light scattering and transmission electron microscopy at cryogenic temps. (cryo-TEM) were employed to characterize the microstructure of the native and hydrophobized GOx assemblies in aq. soln. [on SciFinder(R)]
Baszkin A, Boissonnade MM, Kamyshny A, Magdassi S. Native and Hydrophobically Modified Human Immunoglobulin G at the Air/Water Interface. J. Colloid Interface Sci.Journal of Colloid and Interface Science. 2001;239 (1) :1 - 9.Abstract
The adsorption of human IgG at the air/water interface was monitored both by the in situ radiotracer technique using [14C] labeled IgG and by surface tension measurements. The results reveal that adsorption of IgG from single protein systems displays bimodality due to mol. rearrangements at the interface. Above the threshold value of 1.5×10-2 mg/mL soln. concn., adsorbed IgG mols. reoriented from the side-on to the end-on configuration. The existence of a lag time which did not appear in Γ=f(t) curves, was obsd. in Π=f(t) relationships at low protein concns. and was due to the limits of the surface pressure technique to detect protein adsorption. The adsorption of native IgG was also carried out in the presence of a hydrophobized IgG obtained by grafting capryloyl residues to its lysine groups by reaction with N-hydroxysuccinimide ester of caprylic acid, which yielded 19 covalently bound alkyl chains to the IgG mol. (19C8-IgG). This modified IgG exhibited enhanced adsorption at the air/water interface, as manifested by its increased adsorption efficiency relative to the native protein. Sequential and competitive adsorption expts. from binary mixts. of native IgG and 19C8-IgG clearly demonstrate that the displacement of the native protein from the air/water interface strongly depended on the manner of how 19C8-IgG and native IgG competed with each other. When the two proteins competed simultaneously, 19C8-IgG predominantly occupied the available area but when native IgG was adsorbed first, for 2 h, the sequentially adsorbed 19C8-IgG was incapable of substantially displacing it from the interface. (c) 2001 Academic Press. [on SciFinder(R)]
Baszkin A, Boissonnade MM, Kamyshny A, Magdassi S. Adsorption of Native and Hydrophobically Modified Human Immunoglobulin G on Polyethylene Solid Films: Specific Recognition of Adsorbed Layers. J. Colloid Interface Sci.Journal of Colloid and Interface Science. 2001;244 (1) :18 - 23.Abstract
The in situ adsorption/desorption studies of 14C-labeled human IgG were performed at the polyethylene (PE)/aq. soln. interface. The results reveal that the adsorbed protein mols. were predominantly packed in the end-on orientation. Desorption expts. showed that upon rinsing with buffer only minute fractions of adsorbed IgG could be removed from the PE surface. Both the competitive and the sequential adsorption measurements from the binary mixts. of hydrophobic IgG modified by attachment of 19 caprylic chains (19C8-IgG) and [14C]IgG confirm that native IgG strongly adhered to the PE films. The specific recognition ability of adsorbed human IgG layers was studied by using specific (goat anti-human) IgG and nonspecific (goat anti-rabbit) IgG. It was shown that the prevailing effect of the interaction of [14C]IgG adsorbed onto PE with the specific antibody was the increase in the surface radioactivity, which was attributed to the formation of a more densely packed layer of IgG mols. at the PE surface. It was also demonstrated that, whereas the specific antibody preadsorbed onto PE films retained the recognition ability relative to human IgG, its hydrophobic modification resulted in a substantial decrease in this ability. (c) 2001 Academic Press. [on SciFinder(R)]
Kamyshny A, Lagerge S, Partyka S, Relkin P, Magdassi S. Adsorption of Native and Hydrophobized Human IgG onto Silica: Isotherms, Calorimetry, and Biological Activity. LangmuirLangmuir. 2001;17 (26) :8242 - 8248.Abstract
Adsorption onto silica of native human IgG and its hydrophobized forms prepd. by covalent attachment of 11, 25, and 52 C8 alkyl chains was studied. All hydrophobized IgGs spontaneously form micelle-like aggregates (nanoclusters) in aq. solns. with a mean diam. of 40 nm. Adsorption isotherms are of a high affinity type. The plateau surface concn. of the isotherms depends on the degree of the protein modification, increasing for 11C8-IgG and 25C8-IgG and decreasing for 52C8-IgG as compared with the native protein. The isothermal enthalpies of adsorption for the native and modified IgGs at all degrees of silica surface coverage were endothermic, i.e., the adsorption process is entropically driven. For the native IgG, the adsorption isotherm is apparently reversible, while the isotherms for the modified forms display distinct hysteresis. The biol. (immunol.) activity of the desorbed mols. was evaluated, and it was found that all forms of IgG which were desorbed from silica display reduced ability to react with a specific antibody, goat anti-human IgG, compared to the corresponding forms before adsorption. The immunoassay on desorbed IgGs indicated that hydrophobic modification of the mol. reduced structural alterations obsd. on adsorption of the native IgG. The decrease in activity was much less pronounced in the range of surface coverage close to the plateau values. Possible mechanisms of adsorption of the hydrophobized forms of IgG are discussed. [on SciFinder(R)]
Magdassi S, Kamyshny A, Baszkin A. Interfacial properties of hydrophobically modified biomolecules: fundamental aspects and applications. J. Dispersion Sci. Technol.Journal of Dispersion Science and Technology. 2001;22 (4) :313 - 322.Abstract
A review. This review describes the interfacial behavior of biomols., which were converted to more hydrophobic derivs. by covalent attachment of hydrophobic chains. The mols. presented are proteins (glucose oxidase, IgG, gelatin, ovalbumin) and polysaccharides (CM-cellulose, pullulan). In general, it was found that such hydrophobically modified biomols. have enhanced surface activity and ability to penetrate into phospholipid monolayers. In addn., it has been demonstrated, that such mols. can be used as efficient emulsifiers and foaming agents, and in unique biomedical application based on combining the surface activity and recognition ability. [on SciFinder(R)]
Relkin P, Kamyshny A, Magdassi S. Changes in calorimetric parameters and solvent accessibility of hydrophobic groups in native and chemically modified immunoglobulin G. J. Phys. Chem. BJournal of Physical Chemistry B. 2000;104 (20) :4980 - 4985.Abstract
Structural rearrangements and aggregation resulting from covalent modification of human IgG by caprylic ester of N-hydroxysuccinimide were studied by differential scanning calorimetry, dynamic light scattering, and ANS-binding spectrofluorimetry. The thermogram for the native IgG displays only one transition peak (Tmax = 68°, ΔH = 20.9 J/g). For the chem. modified IgG the temps. corresponding to the initial and maximal deviations of the heat flow as well as the area under the transition peak decreased as the no. of attached alkyl groups increases. This finding may be explained by weakening the intramol. interactions responsible for the rigidity of the IgG mol. structure and by an increase in the protein-protein interactions for the modified IgG. Dynamic light scattering data indicate spontaneous aggregation of the modified IgG mols. in aq. soln.; the size of aggregates depends on the modification degree. These data correlate with a drastic increase in the surface hydrophobicity index for IgG mols. with an increase in the no. of attached alkyl chains. [on SciFinder(R)]