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Ethylene Glycol (ethylene + glycol)
Terms modified by Ethylene Glycol Selected AbstractsDesign of Biomolecular Interfaces Using Liquid Crystals Containing Oligomeric Ethylene GlycolADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Zhongqiang Yang Abstract An investigation of nematic liquid crystals (LCs) formed from miscible mixtures of 4-cyano-4,-pentylbiphenyl (5CB) and 2-(2-[2-{2-(2,3-difluoro-4-{4-(4- trans -pentylcyclohexyl)-phenyl-phenoxy)ethoxy}ethoxy]ethoxy)ethanol (EG4-LC) is reported, the latter being a mesogen with a tetra(ethylene glycol) tail. Quantitative characterization of the ordering of this LC mixture at biologically relevant aqueous interfaces reveals that addition of EG4-LC (1%,5% by weight) to 5CB causes a continuous transition in the ordering of the LC from a planar (pure 5CB) to a perpendicular (homeotropic) orientation. The homeotropic ordering is also seen in aqueous dispersions of micrometer-sized droplets of the LC mixture, which exhibit enhanced stability against coalescence. These observations and others, all of which suggest partitioning of the EG4-LC from the bulk of the LC to its aqueous interface, are complemented by measurements of the adsorption of bovine serum albumin to the aqueous,LC interface. Overall, the results demonstrate a general and facile approach to the design of LCs with interfaces that present biologically relevant chemical functional groups, assume well-defined orientations at aqueous interfaces, and lower non-specific protein adsorption. The bulk of the LC serves as a reservoir of EG4-LC, thus permitting easy preparation of these interfaces and the potential for spontaneous repair of the EG4-decorated interfaces during contact with biological systems. [source] Synthesis and Characterization of Block Copolymers of , -Caprolactone and DL -Lactide Initiated by Ethylene Glycol or Poly(ethylene glycol)MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2003Ming-Hsi Huang Abstract Biodegradable copolymers were prepared by ring-opening polymerization of sequentially added , -caprolactone and DL -lactide in the presence of ethylene glycol or poly(ethylene glycol), using zinc metal as catalyst. Polymerization was performed in bulk and yielded block copolymers with predetermined PEG/PCL/PLA segments. The obtained polymers were characterized by 1H NMR, SEC, IR, DSC, TGA, and X-ray diffraction. Data showed that the copolymers preserved the excellent thermal behavior inherent to PCL. The crystallinity of PLA-containing copolymers was reduced with respect to PCL homopolymer. The presence of both hydrophilic PEG and fast degrading PLA blocks should improve the biocompatibility and biodegradability of the materials, which are of interest for applications as substrate in drug delivery or as scaffolding in tissue engineering. Block copolymerization of , -caprolactone and DL -lactide initiated by dihydroxyl PEG. [source] Vitrification of In Vitro -produced Bovine Embryos by Addition of Ethylene Glycol in One-stepREPRODUCTION IN DOMESTIC ANIMALS, Issue 5 2006DJ Walker Contents The objective of this study was to simplify two-step addition of cryoprotectant for vitrification of bovine embryos by developing a one-step procedure. Survival was calculated as a percentage of non-vitrified controls developed from the same batch of oocytes. In experiment 1, bovine blastocysts were vitrified following one- or two-step addition of cryoprotectant. Exposure of embryos to cryoprotectant in one-step resulted in survival rates not significantly lower (p > 0.1) than those obtained by two-step addition (85% vs 98%, respectively). Based on these results, experiments 2,4 were designed to test one-step addition of cryoprotectant more rigorously. Experiment 2 exposed day 7 blastocysts to 6, 7 or 8 m ethylene glycol for 2.5 or 3.5 min. At 24 h post-vitrification, survival of embryos was similar, irrespective of ethylene glycol concentration or exposure time (6 m 38%, 7 m 51%, 8 m 59%; 2.5 min 54%, 3.5 min 45%). In experiment 3, blastocysts were exposed to 7 m ethylene glycol for shorter times (30 or 60 s); 30 s exposure resulted in decreased survival (8% vs 31%, p < 0.05). Experiment 4 concerned one-step addition of cryoprotectant to day 6 bovine morulae, exposed to 7 m ethylene glycol for 1 or 1.5 min. There was no difference in survival between exposure times of 1 or 1.5 min (28% vs 45%, respectively; p > 0.1). It is unclear why many embryos survive vitrification with one-step addition of cryoprotectant, but others do not. Although, one-step addition of cryoprotectant simplifies the vitrification procedure, survival rates were inadequate for routine cryopreservation of in vitro -produced bovine embryos. [source] ChemInform Abstract: Synthesis of Novel 2-Alkyl Substituted Oleobenzimidazole Derivatives Using Ethylene Glycol as Solvent.CHEMINFORM, Issue 15 2009K. M. Hosamani Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Oxidative Transformation of 1,3-Cyclopentadiene in a System CuBr2 -Ethylene Glycol.CHEMINFORM, Issue 45 2003M. Ya. Abstract For Abstract see ChemInform Abstract in Full Text. [source] Selective Phenolic Acylation of 10-Hydroxycamptothecin Using Poly (Ethylene Glycol) Carboxylic Acid.CHEMINFORM, Issue 18 2003Richard B. Greenwald No abstract is available for this article. [source] Poly(Ethylene Glycol)-Supported Proline: A Versatile Catalyst for the Enantioselective Aldol and Iminoaldol Reactions.CHEMINFORM, Issue 44 2002Maurizio Benaglia Abstract For Abstract see ChemInform Abstract in Full Text. [source] Chemistry of Ethylene Glycol on a Rh(100) Single-Crystal SurfaceCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 9 2009Maarten Abstract The adsorption and decomposition of ethylene glycol on Rh(100) have been studied with temperature-programmed reaction spectroscopy and reflection absorption infrared spectroscopy. Ethylene glycol adsorbs onto the surface via the hydroxyl groups. At 150,K, both hydroxyl bonds are broken, forming an ethylenedioxy intermediate. At high coverage, a portion of the ethylene glycol molecules dehydrogenate only one hydroxyl bond, forming a monodentate species. These intermediates decompose further, with complete dehydrogenation and simultaneous CC bond breaking occurring at around 290,K. Hydrogen and carbon monoxide are formed, which desorb at 290 and 500,K, respectively. [source] Analytical characterization of PEG polymers by MEKCELECTROPHORESIS, Issue 4 2010María R. Plata Abstract Characterization of PEGs with average molecular masses of up to 2000 has been achieved using MEKC with UV detection. A rapid derivatization procedure with phenyl isocyanate using microwave radiation, in order to introduce chromophore groups in PEGs, has been developed involving a reaction time of 60,s. Different optimized conditions in accordance with the molecular weight have been studied to obtain the oligomer separation. The weight-average molecular mass the number-average molecular mass and the degree of polydispersity (molecular mass distribution) were calculated for the different PEGs obtaining similar results with those certified for standards. A good precision was obtained for characterizing the different oligomers. Ethylene glycol was used as the internal standard for the analysis of low-molecular-weight PEGs. The developed method was satisfactorily applied to the characterization of these polymers in several real samples, such as lubricant eye drops, toothpaste, tap water and eye make-up remover. [source] The influence of temperature and osmolyte on the catalytic cycle of cytochrome c oxidaseFEBS JOURNAL, Issue 2 2003Jack A. Kornblatt The influence of temperature on cytochrome c oxidase (CCO) catalytic activity was studied in the temperature range 240,308 K. Temperatures below 273 K required the inclusion of the osmolyte ethylene glycol. For steady-state activity between 278 and 308 K the activation energy was 12 kcal·mol,1; the molecular activity or turnover number was 12 s,1 at 280 K in the absence of ethylene glycol. CCO activity was studied between 240 and 277 K in the presence of ethylene glycol. The activation energy was 30 kcal·mol,1; the molecular activity was 1 s,1 at 280 K. Ethylene glycol inhibits CCO by lowering the activity of water. The rate limitation in electron transfer (ET) was not associated with ET into the CCO as cytochrome a was predominantly reduced in the aerobic steady state. The activity of CCO in flash-induced oxidation experiments was studied in the low temperature range in the presence of ethylene glycol. Flash photolysis of the reduced CO complex in the presence of oxygen resulted in three discernable processes. At 273 K the rate constants were 1500 s,1, 150 s,1 and 30 s,1 and these dropped to 220 s,1, 27 s,1 and 3 s,1 at 240 K. The activation energies were 5 kcal·mol,1, 7 kcal·mol,1, and 8 kcal·mol,1, respectively. The fastest rate we ascribe to the oxidation of cytochrome a3, the intermediate rate to cytochrome a oxidation and the slowest rate to the re-reduction of cytochrome a followed by its oxidation. There are two comparisons that are important: (a) with vs. without ethylene glycol and (b) steady state vs. flash-induced oxidation. When one makes these two comparisons it is clear that the CCO only senses the presence of osmolyte during the reductive portion of the catalytic cycle. In the present work that would mean after a flash-induced oxidation and the start of the next reduction/oxidation cycle. [source] Highly Convenient, Clean, Fast, and Reliable Sonogashira Coupling Reactions Promoted by Aminophosphine-Based Pincer Complexes of Palladium Performed under Additive- and Amine-Free Reaction ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009Jeanne Abstract Sequential addition of 1,1,,1,,-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to toluene solutions of (cyclooctadiene)palladium dichloride [Pd(cod)(Cl)2] under nitrogen in "one pot" almost quantitatively yielded the aminophosphine-based pincer complexes {[C6H3 -2,6-(XP{piperidinyl}2)2]Pd(Cl)} (X=NH 1; X=O 2). Complex 1 (and to a minor extent 2) proved to be efficient Sonogashira catalysts, which allow the quantitative coupling of various electronically deactivated and/or sterically hindered and functionalized aryl iodides and aryl bromides with several alkynes as coupling partners within very short reaction times and low catalyst loadings. Importantly, in contrast to most of the Sonogashira catalysts, which either are both air- and moisture-sensitive and/or require the addition of co-catalysts, such as copper(I) iodide [CuI], for example, or a large excess of an amine, the coupling reactions were carried out without the use of amines, co-catalysts or other aditives and without exclusion of air and moisture. Moreover, the desired products were exclusively formed (no side-products were detected) without employing an excess of one of the substrates. Ethylene glycol and potassium phosphate (K3PO4) were found to be the ideal solvent and base for this transformation. Experimental observations strongly indicate that palladium nanoparticles are not the catalytically active form of 1 and 2. On the other hand, their transformation into another homogeneous catalytically active species cannot be excluded. [source] Synthesis and characterization of multiblock copolymers composed of poly(5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one) outer blocks and poly(L -lactide) inner blocksJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2006Jamie M. Messman Abstract Ethylene glycol (EG) initiated, hydroxyl-telechelic poly(L -lactide) (PLLA) was employed as a macroinitiator in the presence of a stannous octoate catalyst in the ring-opening polymerization of 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) with the goal of creating A,B,A-type block copolymers having polycarbonate outer blocks and a polyester center block. Because of transesterification reactions involving the PLLA block, multiblock copolymers of the A,(B,A)n,B,A type were actually obtained, where A is poly(5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one), B is PLLA, and n is greater than 0. 1H and 13C NMR spectroscopy of the product copolymers yielded evidence of the multiblock structure and provided the lactide sequence length. For a PLLA macroinitiator with a number-average molecular weight of 2500 g/mol, the product block copolymer had an n value of 0.8 and an average lactide sequence length (consecutive C6H8O4 units uninterrupted by either an EG or MBC unit) of 6.1. For a PLLA macroinitiator with a number-average molecular weight of 14,400 g/mol, n was 18, and the average lactide sequence length was 5.0. Additional evidence of the block copolymer architecture was revealed through the retention of PLLA crystallinity as measured by differential scanning calorimetry and wide-angle X-ray diffraction. Multiblock copolymers with PLLA crystallinity could be achieved only with isolated PLLA macroinitiators; sequential addition of MBC to high-conversion L -lactide polymerizations resulted in excessive randomization, presumably because of residual L -lactide monomer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6817,6835, 2006 [source] Nanosized CdSe Particles Synthesized by an Air Pressure Solution Process Using Ethylene-Glycol-Based SolventJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2010Tao Wang Nanosized CdSe particles were synthesized at a temperature of 115°,175°C by a solution method with air pressure condition. Ethylene glycol (EG) was used as the main solvent and sodium selenite and cadmium nitrate-tetrahydrate as inorganic sources. The influence of refluxing temperature and time on growth morphology and crystallization was investigated by transmission electron microscope, high-resolution transmission electron microscope, and X-ray diffraction. The chemical reaction was deducted based on X-ray photoelectron spectra. The optical absorption property was measured by UV-vis. The CdSe nanoparticles synthesized through this EG solvent system was single wurtzite crystallization and had a nanoscale size below 15 nm diameter with a narrow size distribution. The reduction of Se4+,Se0,Se2,and the disproportionation of Se0 occurred during the synthetic process and dominated the chemical reaction. [source] An Alcohol Oxidase Dipstick Rapidly Detects Methanol in the Serum of MiceACADEMIC EMERGENCY MEDICINE, Issue 12 2007Jason B. Hack MD Background Patients presenting with ingestions of methanol and ethylene glycol pose a significant challenge to emergency physicians. The decision to initiate antidotal therapy must be made quickly and is currently based on the presence of indirect signs, symptoms, and laboratory tests, because no real-time diagnostic test exists to measure these substances. Objectives To determine whether a commercially available ethanol-in-saliva detecting dipstick (ALCO-Screen) would be a reliable and rapid indicator of toxic alcohol presence in the serum of an animal model. Methods Fifty mice randomly received intraperitoneal doses of methanol, ethylene glycol, or ethanol to induce serum concentrations of approximately 5,400 mg/dL. Thirty minutes after injection, serum was obtained. Serum was both applied to the dipstick and frozen for definitive concentration determination by gas chromatography. After 2 minutes, dipsticks were evaluated for color change by a blinded observer and photographed to be evaluated by other blinded observers at a later time. Results All concentrations of methanol ,5 mg/dL consistently caused a color change on the ALCO-Screen. Ethylene glycol reliably caused a color change at ,300 mg/dL. There was significant agreement among multiple observers whether or not color change had occurred using the ALCO-Screen. Conclusions A commercially available dipstick that uses an alcohol oxidase colorimetric reaction reliably and rapidly detects very low serum concentrations of methanol but not ethylene glycol in this animal model. This color change is easily detected by most observers. [source] Chemistry of Ethylene Glycol on a Rh(100) Single-Crystal SurfaceCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 9 2009Maarten Abstract The adsorption and decomposition of ethylene glycol on Rh(100) have been studied with temperature-programmed reaction spectroscopy and reflection absorption infrared spectroscopy. Ethylene glycol adsorbs onto the surface via the hydroxyl groups. At 150,K, both hydroxyl bonds are broken, forming an ethylenedioxy intermediate. At high coverage, a portion of the ethylene glycol molecules dehydrogenate only one hydroxyl bond, forming a monodentate species. These intermediates decompose further, with complete dehydrogenation and simultaneous CC bond breaking occurring at around 290,K. Hydrogen and carbon monoxide are formed, which desorb at 290 and 500,K, respectively. [source] Ambient-temperature copper-catalyzed atom transfer radical polymerization of methacrylates in ethylene glycol solventsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2005Solomon M. Kimani Abstract The use of ethylene glycol solvents in the room-temperature atom transfer radical polymerization (ATRP) of various hydrophobic and hydrophilic methacrylates is demonstrated. Unlike many of the very polar solvents described in the literature for room-temperature ATRP, these solvents have good solvency for a wide range of polymers and monomers and are cheap and relatively nontoxic. Ethylene glycols with one hydroxyl and one methoxy group, such as tri(ethylene glycol) monomethyl ether (TEGMME), provide optimal results. The polymerization of methyl methacrylate in TEGMME with CuBr/N,N,N,N,,N,-pentamethyldiethylenetriamine as the catalyst requires the addition of CuCl2 at the beginning of the reaction to produce well-controlled polymerizations. This leads to polymers with predictable molecular weights and relatively narrow polydispersities. Polymerization in solvents that are fully methoxy-capped terminate prematurely because of catalyst precipitation. The electrochemical behavior of copper complexes in selected solvents is examined to determine why these solvents provide good rates at room temperature. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1588,1598, 2005 [source] Methacrylate-based monolithic column with mixed-mode hydrophilic interaction/strong cation-exchange stationary phase for capillary liquid chromatography and pressure-assisted CECELECTROPHORESIS, Issue 19 2008Jian Lin Abstract A novel porous polymethacrylate-based monolithic column by in situ copolymerization of 3-sulfopropyl methacrylate (SPMA) and pentaerythritol triacrylate in a binary porogenic solvent consisting of cyclohexanol/ethylene glycol was prepared. The monolith possessed in their structures bonded sulfonate groups and hydroxyl groups and was evaluated as a hydrophilic interaction and strong cation-exchange stationary phases in capillary liquid chromatography (cLC) and pressure-assisted CEC using small polar neutral and charged solutes. While the SPMA was introduced as multifunctional monomer, the pentaerythritol triacrylate was used to replace ethylene glycol dimethacrylate as cross-linker with much more hydrophilicity due to a hydroxyl sub-layer. The different characterization of monolithic stationary phases were specially designed and easily prepared by altering the amount of SPMA in the polymerization solution as well as the composition of the porogenic solvent for cLC and pressure-assisted CEC. The resulting monolith showed the different trends about the effect of the permeabilities on efficiency in the pressure-assisted CEC and cLC modes. A typical hydrophilic interaction chromatography mechanism was observed at higher organic solvent content (ACN%>70%) for polar neutral analytes. For polar charged analytes, both hydrophilic interaction and electrostatic interaction contributed to their retention. Therefore, for charged analytes, selectivity can be readily manipulated by changing the composition of the mobile phase (e.g., pH, ionic strength and organic modifier). With the optimized monolithic column, high plate counts reaching greater than 170,000,plates/m for pressure-assisted CEC and 105,000 plates/m for cLC were easily obtained, respectively. [source] Bis(4,5-dimethoxy-2-nitrophenyl)ethylene Glycol: A New and Efficient Photolabile Protecting Group for Aldehydes and Ketones.CHEMINFORM, Issue 40 2005Srinivas Kantevari Abstract For Abstract see ChemInform Abstract in Full Text. [source] Transformation of a zinc inclusion complex to wurtzite ZnS microflowers under solvothermal conditionsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2010Liwei Mi Abstract Wurtzite zinc sulfide (ZnS) microflowers were synthesized successfully by a convenient solvothermal route in ethylene glycol (EG) and ethylenediamine (EN) using thiourea and zinc inclusion complex as starting materials. The inclusion complex {[Zn(bipy)2(H2O)2](4-Cl-3-NH2 -C6H3SO3)2(bipy) (H2O)2}n was achieved by the reaction of zinc oxide (ZnO) and 4-Cl-3-NH2 -C6H3SO3 with the bridging ligand bipy under moderate conditions, in which bipy is 4,4,-bipyridine and 4-Cl-3-NH2C6H3SO3NH is 4-Chloro-3-aminobenzene sulfonic acid. The phase purity of bulk products was confirmed by powder X-ray diffraction and element analysis. The factors that might affect the purity of the ZnS product during the synthesis were discussed in detail. It was found that the products were significantly affected by the mixed solvents and the starting materials. X-ray single crystal diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) were used to characterize the products. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and characterization of Nd, Yb , yttrium oxide nanopowders obtained by sol-gel methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2007A. Rzepka Abstract Nanopowders of Y2O3 pure, doped and codoped by Nd3+, Yb3+ were obtained by sol-gel method. Solution with ethylene glycol was choosed as the proper solution where crystallites of powder with Nd and Yb dopants had the same size. Finally the one-phased compounds of Y2O3 doped 0.5 at% Nd and 1, 2 or 4 at% Yb were obtained. Grain growth and their morphology were investigated in various temperature and time of heating. The changes of crystallite sizes and lattice constants in relation to the heating time and temperature for the composition Y2O3 doped 0.5 at% Nd and 2 at% Yb are presented. Y2O3 containing 0,5 at% of Nd exhibits intense luminescence bands centered at 920 nm, 1100 nm and 1360 nm whereas a single band at about 1020 nm appears in samples co-doped with neodymium and ytterbium. Luminescence spectra recorded did not depend on the sample preparation procedure and size of grains. OH impurity affects critically the relaxation dynamics of luminescent ion in nanopowders. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electrochemically Induced Formation of Surface-Attached Temperature-Responsive Hydrogels.ELECTROANALYSIS, Issue 9 2010Amperometric Glucose Sensors with Tunable Sensor Characteristics Abstract Employing thermally responsive hydrogels, the design of an amperometric glucose sensor is proposed. The properties of the biosensor can be modulated upon changing the temperature. Homo- and copolymers of N -isopropylacrylamide (NIPAm) and oligo(ethylene glycol) methacrylate (OEGMA) were prepared by electrochemically induced polymerization thus yielding surface-attached hydrogels. The growth of the films as well as the change in the film thickness in dependence from the temperature were investigated by means of an electrochemical quartz crystal microbalance (EQCM). The layer thickness in the dry state ranged from 20 to 120,nm. The lower critical solution temperature (LCST) of the hydrogel increases with increasing content of the more hydrophilic OEGMA. Hence, the swelling in aqueous electrolyte is composition dependent and can be adjusted by selecting a specific NIPAm to OEGMA ratio. All homo- and copolymer films showed good biocompatibility and no fouling could be observed during exposing the surfaces to human serum albumin. For amperometric glucose detection, glucose oxidase was entrapped in the films during electrochemically-induced polymerization. Both the apparent Michaelis constant (K and the apparent maximum current (i as determined by amperometry could be adjusted both by the film composition as well as the operation temperature. [source] Impedance Spectroscopy: A Powerful Tool for Rapid Biomolecular Screening and Cell Culture MonitoringELECTROANALYSIS, Issue 23 2005Isaac Abstract Dielectric spectroscopy or Electrochemical impedance spectroscopy (EIS) is traditionally used in corrosion monitoring, coatings evaluation, batteries, and electrodeposition and semiconductor characterization. However, in recent years, it is gaining widespread application in biotechnology, tissue engineering, and characterization of biological cells, disease diagnosis and cell culture monitoring. This article discusses the principles and implementation of dielectric spectroscopy in these bioanalytical applications. It provides examples of EIS as label-free, mediator-free strategies for rapid screening of biocompatible surfaces, monitoring pathogenic bacteria, as well as the analysis of heterogeneous systems, especially biological cells and tissues. Descriptions are given of the application of nanoparticles to improve the analytical sensitivities in EIS. Specific examples are given of the detection of base pair mismatches in the DNA sequence of Hepatitis B disease, TaySach's disease and Microcystis spp. Others include the EIS detection of viable pathogenic bacteria and the influence of nanomaterials in enhancing biosensor performance. Expanding applications in tissue engineering such as adsorption of proteins onto thiolated hexa(ethylene glycol)-terminated (EG6) self-assembled monolayer (SAM) are discussed. [source] The Oriented Self-Assembly of Magnetic Fe3O4 Nanoparticles into Monodisperse Microspheres and Their Use as Substrates in the Formation of Fe3O4 NanorodsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2008Guangcheng Xi Abstract We describe a facile solvothermal route for the large-scale preparation of ferromagnetic Fe3O4 sub-micrometer spheres and nanorods by using FeCl3 as the iron source, oleic acid as the surfactant, and ethylene glycol as the reducing agent and solvent. The as-synthesized Fe3O4 microspheres are composed of a mess of Fe3O4 nanoparticles with a size of 10 nm and have nearly monodisperse diameters that can be controlled in the range 100,410 nm. HRTEM images and SAED patterns show that these microspheres present a "single-crystalline" nature, which can be attributed to the highly oriented assembly of the small Fe3O4 nanoparticles. Interestingly, by using the pre-synthesized Fe3O4 microspheres as the growth substrate, single-crystalline Fe3O4 nanorods can be formed on the surfaces of the microspheres. These nanorods are about 7,20 nm in diameter and 120,400 nm in length, and have smooth surfaces. The formation mechanisms of the Fe3O4 microspheres and nanorods have been investigated and discussed. Furthermore, the magnetic properties of the as-synthesized microspheres and nanorods have also been investigated and the magnetization saturation values are 74.6 and 92.3 emu/g, respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Benzene-di- N -substituted carbamates as conformationally constrained analogs of Pseudomonas lipase substratesEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 11 2007Ming-Cheng Lin Abstract Benzene-1,2-, -1,3-, and -1,4-di- N -substituted carbamates (1,15) are synthesized as the constrained analogs of gauche, eclipsed, and anti conformations of diesters of ethylene glycol, respectively. Carbamates 1,15 are characterized as the pseudo-substrate inhibitors of Pseudomonas species lipase. Long-chain carbamates are more potent inhibitors than short-chain ones. Different geometries of benzene-di-substituted carbamates, such as benzene-1,2-di- N -octylcarbamate (3) (ortho compound), benzene-1,3-di- N -octylcarbamate (8) (meta compound), and benzene-1,4-di- N -octylcarbamate (13) (para compound), show similar inhibitory potencies for the enzyme. In other words, kinetic data suggest that the enzyme does not discriminate ortho, meta, and para geometries of these constrained analogs. [source] The effect of polymers and surfactants on the pour point of palm oil methyl estersEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 4 2007Cheah Han Sern Abstract The objective of this research was to find some additives suitable to reduce the pour point (PP) of palm oil methyl esters. The PP properties of palm oil methyl esters (biodiesel) were evaluated with commercially available polymeric and surfactant compounds with various polarities, molecular sizes and structures. The compounds under study were poly(ethylene glycol), poly(methyl methacrylate), poly(ethylene-co-vinyl acetate), poly(styrene-co-maleic anhydride), poly(ethylene glycol) distearate, poly-(octadecyl methacrylate), poly(1-decene), poly(maleic anhydride- alt -1-octadecene), caprylic acid sodium salt, N -lauroylsarcosine sodium salt, polyoxyethylene(2) cetyl ether and polyoxyethylene(10) cetyl ether. Seven out of the twelve polymeric compounds tested were miscible in palm oil methyl esters due to similar polarities of the solute and biodiesel. The blends of the resultant seven polymeric compounds in palm oil methyl esters were evaluated respectively for their effect on the PP property. Poly-(maleic anhydride- alt -1-octadecene) was able to improve the PP of palm oil methyl esters from 12 to 6,°C when 2,wt-% was added. The cloud point was reduced from 12.9 to 8.1,°C, and the cold filter plugging point was reduced from 12 to 7,°C, whilst the flash point value remained unchanged at 156,°C when 2,wt-% of poly(maleic anhydride- alt -1-octadecene) was added to the palm oil methyl esters. [source] Proteolytically Degradable Photo-Polymerized Hydrogels Made From PEG,Fibrinogen Adducts,ADVANCED ENGINEERING MATERIALS, Issue 6 2010Daniel Dikovsky Abstract We develop a biomaterial based on protein,polymer conjugates where poly(ethylene glycol) (PEG) polymer chains are covalently linked to multiple thiols on denatured fibrinogen. We hypothesize that conjugation of large diacrylate-functionalized linear PEG chains to fibrinogen could govern the molecular architecture of the polymer network via a unique protein,polymer interaction. The hypothesis is explored using carefully designed shear rheometry and swelling experiments of the hydrogels and their precursor PEG/fibrinogen conjugate solutions. The physical properties of non-cross-linked and UV cross-linked PEGylated fibrinogen having PEG molecular weights ranging from 10 to 20,kDa are specifically investigated. Attaching multiple hydrophilic, functionalized PEG chains to the denatured fibrinogen solubilizes the denatured protein and enables a rapid free-radical polymerization cross-linking reaction in the hydrogel precursor solution. As expected, the conjugated protein-polymer macromolecular complexes act to mediate the interactions between radicals and unsaturated bonds during the free-radical polymerization reaction, when compared to control PEG hydrogels. Accordingly, the cross-linking kinetics and stiffness of the cross-linked hydrogel are highly influenced by the protein,polymer conjugate architecture and molecular entanglements arising from hydrophobic/hydrophilic interactions and steric hindrances. The proteolytic degradation products of the protein,polymer conjugates proves to be were different from those of the non-conjugated denatured protein degradation products, indicating that steric hindrances may alter the proteolytic susceptibility of the PEG,protein adduct. A more complete understanding of the molecular complexities associated with this type of protein-polymer conjugation can help to identify the full potential of a biomaterial that combines the advantages of synthetic polymers and bioactive proteins. [source] Photopolymerizable Hydrogels Made from Polymer-Conjugated Albumin for Affinity-Based Drug Delivery,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010Liat Oss-Ronen As a drug delivery vehicle, biodegradable albumin hydrogels can combine the high binding capacity of albumin with the structural stability of a polymeric hydrogel network to enable controlled release of small molecules based on both binding affinity and physical interactions. In the present study, we report on the development of a hybrid hydrogel composed of albumin conjugated to poly(ethylene glycol) (PEG) for drug delivery applications where controlled release is accomplished using the natural affinity of the drugs to the serum albumin. Bovine serum albumin was conjugated to PEG-diacrylate having a molecular weight of 1.5, 4, or 10,kDa to form a PEGylated albumin macromolecule (mono-PEGylated or multi-PEGylated). Biodegradable hydrogels were formed from the PEGylated albumin using photopolymerization. Two model drugs, Warfarin and Naproxen, were used for equilibrium dialysis and release experiments from the hydrogels, both having relatively low molecular weights and a known high affinity for albumin. Equilibrium dialysis experiments showed that multi-PEGylation of albumin significantly decreased the drug affinity to the protein compared to non-PEGylated controls, irrespective of the PEG molecular weight. However, the results from drug release experiments showed that mono-PEGylation of albumin did not change its natural affinity to the drug. Comparing the release profiles with a Fickian diffusion model provided strong evidence that hydrogels containing mono-PEGylated albumin exhibited sub-diffusive drug release properties based on the affinity of the drug to the tethered protein. [source] A Microwave-Assisted Heck Reaction in Poly(ethylene glycol) for the Synthesis of BenzazepinesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2007Valérie Declerck Abstract The Heck reaction of alkylated 2-(trimethylsilyl)ethanesulfonyl (SES)-protected ,-amino esters provides benzazepines in good yields. Good selectivity towards cyclisation was obtained when the reaction was performed in PEG 3400 as the solvent under microwave activation. Cleavage of the SES group with HF provides the corresponding free benzazepine. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A Molecular Brush Approach to Enhance Quantum Yield and Suppress Nonspecific Interactions of Conjugated Polyelectrolyte for Targeted Far-Red/Near-Infrared Fluorescence Cell ImagingADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Kan-Yi Pu Abstract A red-fluorescent conjugated polyelectrolyte (CPE, P2) is grafted with dense poly(ethylene glycol) (PEG) chains via click chemistry and subsequently modified with folic acid to form a molecular brush based cellular probe (P4). P4 self-assembles into a core,shell nanostructure in aqueous medium with an average size of 130 nm measured by laser light scattering. As compared to P2, P4 possesses not only a substantially higher quantum yield (11%), but also reduced nonspecific interactions with biomolecules in aqueous medium due to the shielding effect of PEG. In conjunction with its high photostability and low cytotoxicity, utilization of P4 as a far-red/near-infrared cellular probe allows for effective visualization and discrimination of MCF-7 cancer cells from NIH-3T3 normal cells in a high contrast, selective, and nonviral manner. This study thus demonstrates a flexible molecular brush approach to overcome the intrinsic drawbacks of CPEs for advanced bioimaging applications. [source] A Molecular Brush Approach to Enhance Quantum Yield and Suppress Nonspecific Interactions of Conjugated Polyelectrolyte for Targeted Far-Red/Near-Infrared Fluorescence Cell ImagingADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Kan-Yi Pu Abstract A red-fluorescent conjugated polyelectrolyte (CPE, P2) is grafted with dense poly(ethylene glycol) (PEG) chains via click chemistry and subsequently modified with folic acid to form a molecular brush based cellular probe (P4). P4 self-assembles into a core,shell nanostructure in aqueous medium with an average size of 130 nm measured by laser light scattering. As compared to P2, P4 possesses not only a substantially higher quantum yield (11%), but also reduced nonspecific interactions with biomolecules in aqueous medium due to the shielding effect of PEG. In conjunction with its high photostability and low cytotoxicity, utilization of P4 as a far-red/near-infrared cellular probe allows for effective visualization and discrimination of MCF-7 cancer cells from NIH-3T3 normal cells in a high contrast, selective, and nonviral manner. This study thus demonstrates a flexible molecular brush approach to overcome the intrinsic drawbacks of CPEs for advanced bioimaging applications. [source] | |||||||||||||||||||||||||||||||||||||