Publications by Year: 2002

2002
Lapidot N, Magdassi S, Avnir D, Rottman C, Gans O, Seri-Levy A.; 2002. Stable formulation of topically active ingredients.Abstract
A therapeutic, cosmetic or cosmeceutic compn. for topical application, capable of stabilizing an active ingredient and delivering the active ingredient, comprises a plurality of microcapsules having a core-shell structure. The microcapsules have a diam. of approx. 0.1 to 100 μ. The core of each microcapsule includes at least one active ingredient and is encapsulated within a microcapsular shell. The shell is comprised of at least one inorg. polymer obtained by a sol-gel process, and the shell protects the active ingredient before topical application and is designed to release the active ingredient from the microcapsules following application. The compn. is useful in encapsulating active ingredients, such as benzoyl peroxide, that are unstable in other formulation, or are irritating to the skin. Me salicylate were mixed with tetraethoxysilane (TEOS). The org. phase was emulsified in an aq. soln. contg. 1% cetyltrimethyl ammonium chloride (CTAC) under high shear. This emulsion was then poured into a reactor contg. aq. NaOH soln. at pH 11.5. The soln. was stirred and after 7 days the product was pptd. in a centrifuge. The final product was re-suspended in water contg. 1% polyvinylpyrrolidone to receive a suspension contg. 32.4% Me salicylate encapsulated in silica particles of 0.5-10 μ. [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)]
Lapidot N, Magdassi S, Avnir D, Rottman C, Gans O, Seri-Levy A.; 2002. Sunscreen composition containing sol-gel microcapsules.Abstract
The present invention generally relates to safe and stable sunscreen compns. comprising of at least one sunscreen active ingredient in the form of an inert sol-gel microcapsules encapsulating UV absorbing compds. in any acceptable cosmetic vehicle. The compn. according to the present invention can comprise several UV absorbers that may be encapsulated in the same sol-gel microcapsule or in different capsules. The hydrophobicity/hydrophilicity character of the sol-gel microcapsules can be controlled by selecting suitable sol-gel precursors and suitable reaction conditions and can be chosen to be compatible with the cosmetic vehicle to be used in the sunscreen compn., thus, the present invention facilitates an easy incorporation of the composite sol-gel encapsulated sunscreen in all types of cosmetic vehicles including oil free compns., with no necessary steps of heating or high shear forces. The sunscreen compns. of the present invention can comprise any acceptable UVA and/or UVB absorbing compds. at any desired ratio to obtain a desired accumulative UV screening spectrum. An aq. suspension of silica microcapsules, contg. 35.8% p-methoxycinnamate (OMC) was prepd. An oil in water emulsion contg. liq. paraffin (mineral oil) 5.00, decyl oleate 5.00, dimethicone 1.00, cetearyl alc. 1.00, glyceryl stearate 3.00, potassium cetyl phosphate 2.00, water 47.25, xanthan gum 0.15, propylene glycol 5.00, 2-bromo-2-nitropropane-1,3-diol & methylparaben & phenoxyethanol & propylbaraben 5.00, 88% lactic acid 0.10, and above silica/OMC (25% OMC in water suspension) 30.00%. [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)]