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Metal Chelates (metal + chelate)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Gd(III)-EPTPAC16, a new self-assembling potential liver MRI contrast agent: in vitro characterization and in vivo animal imaging studies,

NMR IN BIOMEDICINE, Issue 4 2008
Suzana Torres
Abstract The recently reported amphiphilic chelate, [Gd(EPTPAC16)(H2O)]2,, forms supramolecular aggregates in aqueous solution by self-assembly of the monomers with a relaxometrically determined critical micellar concentration (CMC) of 0.34,mM. The effect of sonication on the aggregate size was characterized by dynamic light scattering and relaxometry, indicating the presence of premicellar aggregates and an overall decrease in aggregate size and polydispersity upon sonication, slightly below the CMC. {[153Sm](EPTPAC16)(H2O)}2, radiotracer was evaluated in vivo from , scintigraphy and biodistribution in Wistar rats. It was found to depend strongly on the sample concentration, below or above the CMC, and its sonication, in a way that correlates with the effect of the same factors on the size of the aggregates formed in solution. Below CMC, the very large aggregates of the [153Sm]3+ -labeled chelate were persistently and mainly taken up by the lungs, and also by the macrophage-rich liver and spleen. Sonication of this solution led to loss of the lung uptake. Above CMC, the metal chelate was mainly taken up by the liver, with very little uptake by the spleen and lungs. In vivo, dynamic contrast-enhanced (DCE)-MRI evaluation of the micellar [Gd(EPTPAC16)(H2O)]2, compound in Wistar rats showed a persistent hepatic positive-contrast effect in T1 -weighted images, qualitatively similar to the clinically established GdIII -based hepatobiliary-selective agents. No enhancement effect was observed in the lungs because of the scarcity of mobile protons in this organ, despite the scintigraphic evidence of significant lung retention of the [153Sm]3+ -labeled chelate at concentrations below the CMC. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Cloud point preconcentration prior to capillary zone electrophoresis: Simultaneous determination of platinum and palladium at trace levels

ELECTROPHORESIS, Issue 18 2005
Soledad Cerutti Professor
Abstract The incorporation of a cloud point extraction (CPE) step prior to capillary electrophoresis (CE) for simultaneously determining platinum and palladium at sub-,g/L levels is presented and evaluated. The analytes were extracted as 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complexes, at pH,2.0, mediated by micelles of the nonionic surfactant polyethyleneglycolmono- p -nonylphenyl ether (PONPE 7.5). The separation,determination step was developed from 150,,L of the extracted surfactant-rich phase diluted with 50,,L of acetonitrile (ACN). An exhaustive study of the variables affecting the cloud point extraction with PONPE 7.5 and the CZE step was done. The type and composition of the background electrolytes (BGEs) were investigated with respect to separation selectivity, reproducibility, and stability. A BGE of 50,mM monobasic sodium phosphate containing 30% ACN, pH 4.53 was found to be optimal for the separation of metal chelates. Detection was performed at 576,nm. An enrichment factor of 250 was obtained for the preconcentration of 50,mL of sample solution. The detection limits for the preconcentration of 50,mL of sample were 0.04,,g/L for Pt and 0.08,,g/L for Pd. As an analytical demonstration, ultratrace concentrations of platinum and palladium were conveniently quantitated in spiked water and urine samples. [source]

Improved ,-Glucanase Production by a Recombinant Escherichia coli Strain using Zinc-Ion Supplemented Medium

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 3 2007
U. Beshay
Abstract In order to investigate the suitability of different metal chelates for affinity chromatography, an expression vector was constructed. It contained a hybrid ,-glucanase as a model protein fused with a His6 -tag and a secretion cassette providing the ability to secrete ,-glucanase into the culture medium. Supplementation of zinc to the medium led to a rapidly increased expression and release of the target protein into the cultivation medium. Results in respect to the supplementation of the commonly used Terrific Broth "TB-medium" with different metal ions are reported with special emphasis on the influence of zinc ions. A concentration of zinc ions in the order of about 0.175 mM led to optimal results. Batch cultivation under well-controlled conditions showed that the growth behavior did not change significantly by adding zinc ions. Growth in a stirred tank bioreactor was much faster in unsupplemented TB-medium compared to shake flask experiments leading to a much higher biomass concentration (15,g/L instead of 3,g/L). The secretion of ,-glucanase under theses conditions started at the transition into the stationary phase and increased to yield an extracellular activity of 1350,U/mL at the end of the fermentation process. An even higher yield of extracellular ,-glucanase (2800,U/mL) was reached when the fermentation was carried out with TB-medium supplemented with 0.175,mM ZnSO4. [source]

Synthesis, characterization and biological properties of sulfonamide-derived compounds and their transition metal complexes

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2009
Zahid H. Chohan
Abstract Sulfonamide-derived compounds and their first row d-transition metal chelates [cobalt(II), copper(II), nickel(II) and zinc(II)] have been synthesized and characterized. The nature of bonding and structure of all the synthesized compounds have been proposed from magnetic susceptibility and conductivity measurements, IR, 1H and 13C NMR, electron spectra, mass spectrometry and CHN analysis data. The structure of ligand, 4-{[(E)-(5-chloro-2-hydroxyphenyl) methylidene] amino}- N -(4,6-dimethyl pyrimidin-2-yl) benzene sulfonamide has also been determined by X-ray diffraction method. An octahedral geometry has been suggested for all the complexes. The ligands and metal complexes have been screened for their in vitro antibacterial, antifungal and cytotoxic activity. The results of these studies revealed that all compounds showed moderate to significant antibacterial activity against one or more bacterial strains and good antifungal activity against various fungal strains. Copyright © 2009 John Wiley & Sons, Ltd. [source]