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Sample records for metal hfa chelates

  1. Chelation in Metal Intoxication

    Directory of Open Access Journals (Sweden)

    Swaran J.S. Flora

    2010-06-01

    Full Text Available Chelation therapy is the preferred medical treatment for reducing the toxic effects of metals. Chelating agents are capable of binding to toxic metal ions to form complex structures which are easily excreted from the body removing them from intracellular or extracellular spaces. 2,3-Dimercaprol has long been the mainstay of chelation therapy for lead or arsenic poisoning, however its serious side effects have led researchers to develop less toxic analogues. Hydrophilic chelators like meso-2,3-dimercaptosuccinic acid effectively promote renal metal excretion, but their ability to access intracellular metals is weak. Newer strategies to address these drawbacks like combination therapy (use of structurally different chelating agents or co-administration of antioxidants have been reported recently. In this review we provide an update of the existing chelating agents and the various strategies available for the treatment of heavy metals and metalloid intoxications.

  2. Chelation in metal intoxication

    DEFF Research Database (Denmark)

    Aaseth, Jan; Skaug, Marit Aralt; Cao, yang

    2015-01-01

    The present review provides an update of the general principles for the investigation and use of chelating agents in the treatment of intoxications by metals. The clinical use of the old chelators EDTA (ethylenediamine tetraacetate) and BAL (2,3-dimercaptopropanol) is now limited due to the incon......The present review provides an update of the general principles for the investigation and use of chelating agents in the treatment of intoxications by metals. The clinical use of the old chelators EDTA (ethylenediamine tetraacetate) and BAL (2,3-dimercaptopropanol) is now limited due...... to the inconvenience of parenteral administration, their own toxicity and tendency to increase the neurotoxicity of several metals. The hydrophilic dithiol chelators DMSA (meso-2,3-dimercaptosuccinic acid) and DMPS (2,3-dimercapto-propanesulphonate) are less toxic and more efficient than BAL in the clinical treatment...... of heavy metal poisoning, and available as capsules for oral use. In copper overload, DMSA appears to be a potent antidote, although d-penicillamine is still widely used. In the chelation of iron, the thiols are inefficient, since iron has higher affinity for ligands with nitrogen and oxygen, but the new...

  3. Laccase Immobilization by Chelated Metal Ion Coordination Chemistry

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    Qingqing Wang

    2014-09-01

    Full Text Available In this work, amidoxime polyacrylonitrile (AOPAN nanofibrous membrane was prepared by a reaction between PAN nanofibers and hydroxylamine hydrochloride. The AOPAN nanofibrous membranes were used for four metal ions (Fe3+, Cu2+, Ni2+, Cd2+ chelation under different conditions. Further, the competition of different metal ions coordinating with AOPAN nanofibrous membrane was also studied. The AOPAN chelated with individual metal ion (Fe3+, Cu2+, Ni2+, Cd2+ and also the four mixed metal ions were further used for laccase (Lac immobilization. Compared with free laccase, the immobilized laccase showed better resistance to pH and temperature changes as well as improved storage stability. Among the four individual metal ion chelated membranes, the stability of the immobilized enzymes generally followed the order as Fe–AOPAN–Lac > Cu–AOPAN–Lac > Ni–AOPAN–Lac > Cd–AOPAN–Lac. In addition, the immobilized enzyme on the carrier of AOPAN chelated with four mixed metal ions showed the best properties.

  4. Chelation: Harnessing and Enhancing Heavy Metal Detoxification—A Review

    Directory of Open Access Journals (Sweden)

    Margaret E. Sears

    2013-01-01

    Full Text Available Toxic metals such as arsenic, cadmium, lead, and mercury are ubiquitous, have no beneficial role in human homeostasis, and contribute to noncommunicable chronic diseases. While novel drug targets for chronic disease are eagerly sought, potentially helpful agents that aid in detoxification of toxic elements, chelators, have largely been restricted to overt acute poisoning. Chelation, that is multiple coordination bonds between organic molecules and metals, is very common in the body and at the heart of enzymes with a metal cofactor such as copper or zinc. Peptides glutathione and metallothionein chelate both essential and toxic elements as they are sequestered, transported, and excreted. Enhancing natural chelation detoxification pathways, as well as use of pharmaceutical chelators against heavy metals are reviewed. Historical adverse outcomes with chelators, lessons learned in the art of using them, and successes using chelation to ameliorate renal, cardiovascular, and neurological conditions highlight the need for renewed attention to simple, safe, inexpensive interventions that offer potential to stem the tide of debilitating, expensive chronic disease.

  5. Studies on In-situ Chelation/Supercritical Fluid Extraction of Lanthanides and Actinides Using a Radiotracer Technique

    International Nuclear Information System (INIS)

    Lin, Yuehe; Wu, Hong; Smart, Neil G.; Wai, Chien M.

    2001-01-01

    Radioisotope tracer techniques were used to study the process of in-situ chelation/supercritical fluid extraction(SFE) of La3+ and Lu3+ from solid matrix using mixed ligand hexafluoroacetylacetone (HFA) and tributylphosphate (TBP) as chelating agents. A lab-built SFE extactor was used in this study and the extractor design was optimized based on the experimental results. Quantitative recovery of La and Lu was achieved when the extrator design was optimized. Extraction of uranium from real world samples was also investigated to demonstrate the capability of this chelation/SFE technology for environmental remediation applications. A novel on-line back extraction technique for the recovery of metal ions and regeneration of ligands is also reported.

  6. Metal chelate conjugated monoclonal antibodies, wherein the metal is an α emitter

    International Nuclear Information System (INIS)

    Gansow, O.A.; Strand, M.

    1984-01-01

    Methods of manufacturing and purifying metal chelate conjugated monoclonal antibodies are described, wherein the chelated metal emits alpha radiation. The conjugates are suited for therapeutic uses being substantially free of nonchelated radiometal. (author)

  7. Decorporation of metal ions by chelating agents

    International Nuclear Information System (INIS)

    Koenig, T.

    1978-01-01

    Simple model designs to simulate the effect of therapeutical chelating agents on the behaviour of metals in mammal organisms with and without excretion have been derived and analytical solutions given for the corresponding differential equations. The possibilities of these models in the short-term description of plasma kinetics of various metals, the competition of the therapeutical ligands with proteins for the metal and of the metabolism of chelating agents were tested and the properties applying extreme conceivable parameters were analyzed. The simple models were successsively expanded in logical sequence, so that it was possible to qualitatively well describe over a long period of time, the metallic kinetics in plasma, organs and urine, the retention of the ligands and their effect on the metal excretion. Two suggestions were given to describe the so-called after-effect, an increased excretion of the metal at times when the ligand is almost completely excreted and their different behaviour after injecting the metal chelate is given. Calculations on the therapy with several ligand data as well as on dose fractionation are described resting on the ratios in the plutonium-239 chosen model parameters and the determining mechanisms analyzed. (orig./MG) [de

  8. Metal regeneration of iron chelates in nitric oxide scrubbing

    Science.gov (United States)

    Chang, S.G.; Littlejohn, D.; Shi, Y.

    1997-08-19

    The present invention relates to a process of using metal particles to reduce NO to NH{sub 3}. More specifically, the invention concerns an improved process to regenerate iron (II) (CHELATE) by reduction of iron (II) (CHELATE) (NO) complex, which process comprises: (a) contacting an aqueous solution containing iron (II) (CHELATE) (NO) with metal particles at between about 20 and 90 C to reduce NO present, produce ammonia or an ammonium ion, and produce free iron (II) (CHELATE) at a pH of between about 3 and 8. The process is useful to remove NO from flue gas and reduce pollution. 34 figs.

  9. ELECTED PROBLEMS RELATED TO ENVIRONMENTAL HEAVY METALS EXPOSURE AND CHELATION THERAPY

    Directory of Open Access Journals (Sweden)

    Anna Skoczyńska

    2010-09-01

    Full Text Available Background: Exposure to heavy metals leads to functional and metabolic disturbances and many of them are included in pathogenesis of common diseases (arterial hypertension, atherosclerosis, neurodegenerative processes. In this context new therapeutic and prophylactic strategies are necessary. Patients diagnosed with chronic heavy metals intoxication usually require chelation to increase mobilisation of metals from tissues and elimination of them via urine. Acute poisoning with toxic metal may be difficult to diagnosis, especially in case of accidental intoxication or suicidal intention. Patients also require chelation after causative factor is identified. Objectives: To describe some problems connected with toxicity of metals poisoning and to review pharmacologic therapies that could have a role in poisoning with metals. Methods: A review of the literature was carried out and expert opinion expressed. Results/conclusion: Chelation is a common therapy in case of poisoning with toxic metals but it is satisfied only partially. A combined therapy with structurally different chelators or long-term acting chelators could become viable alternatives in the future. A combined therapy with an antioxidant plus chelator may be a good choice in patients chronically poisoned with metals. Exposure to lead should be taken into account during estimation of global cardiovascular risk.

  10. Heavy metal displacement in chelate-irrigated soil during phytoremediation

    Science.gov (United States)

    Madrid, F.; Liphadzi, M. S.; Kirkham, M. B.

    2003-03-01

    Heavy metals in wastewater sewage sludge (biosolids), applied to land, contaminate soils. Phytoremediation, the use of plants to clean up toxic heavy metals, might remove them. Chelating agents are added to soil to solubilize the metals for enhanced phytoextraction. Yet no studies follow the displacement and leaching of heavy metals in soil with and without roots following solubilization with chelates. The objective of this work was to determine the mobility of heavy metals in biosolids applied to the surface of soil columns (76 cm long; 17 cm diam.) with or without plants (barley; Hordeum vulgare L.). Three weeks after barley was planted, all columns were irrigated with the disodium salt of the chelating agent, EDTA (ethylenediamine tetraacetic acid) (0.5 g/kg soil). Drainage water, soil, and plants were analyzed for heavy metals (Cd, Cu, Fe, Mn, Ni, Pb, Zn). Total concentrations of the heavy metals in all columns at the end of the experiment generally were lower in the top 30 cm of soil with EDTA than without EDTA. The chelate increased concentrations of heavy metals in shoots. With or without plants, the EDTA mobilized Cd, Fe, Mn, Ni, Pb, and Zn, which leached to drainage water. Drainage water from columns without EDTA had concentrations of these heavy metals below detection limits. Only Cu did not leach in the presence of EDTA. Even though roots retarded the movement of Cd, Fe, Mn, Ni, Pb, and Zn through the EDTA-treated soil from 1 d (Cd) to 5 d (Fe), the drainage water from columns with EDTA had concentrations of Cd, Fe, Mn, and Pb that exceeded drinking water standards by 1.3, 500, 620, and 8.6 times, respectively. Because the chelate rendered Cd, Fe, Mn, Ni, Pb, and Zn mobile, it is suggested that the theory for leaching of soluble salts, put forward by Nielsen and associates in 1965, could be applied to control movement of the heavy metals for maximum uptake during chelate-assisted phytoremediation.

  11. Chelating impact assessment of biological ad chemical chelates on metal extraction from contaminated soils

    International Nuclear Information System (INIS)

    Manwar, S.; Iram, S.

    2014-01-01

    Soil contamination is the result of uncontrolled waste dumping and poor practices by humans. Of all the pollutants heavy metals are of particular concern due to their atmospheric deposition, leaching capacity and non-biodegradability. Heavy metal containing effluent is discharged into the agricultural fields and water bodies. This results in the accumulation of heavy metals in soil and the crops grown on that soil. Studies have revealed detrimental impacts on soil fertility and the poor health of animals and humans. Phytoextraction is widely researched for remediation of heavy metal contaminated soil. To enhance the effect of phytoextraction heavy metals have to be available to the plants in soluble form. In this study the potential of different chelating agents was assessed in solubilizing the heavy metals making easy for plants to uptake them. For this purpose efficient chemical and biological chelating agent had to be identified. Along with that an optimum dose and application time for chemical chelating agent was determined. Ethylenediamine tetraacetic acid (EDTA), Diethylene triamine pentaacetic acid (DTPA), Nitriloacetic acid (NTA) were applied to the soil, containing Pb, Cr, Cu and Cd, at different concentrations and application time. Aspergillus niger and Aspergillus flavus were incubated in soil for different time periods. In correspondence with findings of the study, Pb and Cr were best solubilized by 5mM EDTA. For Cd and Cu 5mM DTPA carried out efficient chelation. NTA showed relatively inadequate solubilisation, although for Cr it performed equal to EDTA. A. niger and A. flavus instead of solubilizing adsorbed the metals in their biomass. Adsorption was mainly carried out by A. niger. (author)

  12. The solvent extraction of alkali metal ions with β-diketones

    International Nuclear Information System (INIS)

    Munakata, Megumu; Niina, Syozo; Shimoji, Noboru

    1974-01-01

    This work was undertaken to investigate effects of solvent and chelating-agent on the solvent extraction of alkali metal ions by seven β-diketones, acetylacetone (Acac), benzoylacetone (BzA), dipivaloylmethane (DPM), dibenzoylmethane (DBM), thenoyltrifluoloacetone (TTA), benzoyltrifluoroacetone (BFA) and hexafluoroacetylacetone (HFA), and to separate lithium from alkali metals. The extraction of alkali metals increase with increasing donor power of the solvent: i.e., benzene Na>K>Rb>Cs, which is also the order in which the adduct formation of these β-diketone chelates with donor solvents increase. The adduct formations between β-diketone chelates of alkali metals and donor solvents markedly enhance the solubilities of the chelates in solvents and, consequently, the extractabilities of alkali metals with β-diketones. Lithium was extracted with TTA in ether at such a low base concentration that sodium, potassium, rubidium and cesium were hardly extracted, and this enabled to separate lithium from other metals by the use of rubidium hydroxide (0.02 M). An attempt has been made to isolate alkali metal β-diketone chelates and some chelates have been obtained as crystals. The infrared absorption bands arising from C=O and C.=C of TTA shift to lower frequencies in the alkali metal chelates with TTA, and consequently, β-diketones is suggested to coordinate to alkali metal as a bidentate ligand. (JPN)

  13. Modelling chelate-Induced phytoextraction: functional models predicting bioavailability of metals in soil, metal uptake and shoot biomass

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    Pasqualina Sacco

    2006-06-01

    Full Text Available Chelate-induced phytoextraction of heavy metals from contaminated soils requires special care to determine, a priori, the best method of chelate application, in terms of both dose and timing. In fact, the chelate dose must assure the bioavailability of the metal to the plant without increasing leaching risk and giving toxic effects. Three mathematical models are here proposed for usefully interpreting the processes taking place: a increased soil bioavailability of metals by chelants; b metal uptake by plants; c variation in plant biomass. The models are implemented and validated using data from pot and lysimeter trials. Both the chelate dose and the time elapsed since its application affected metal bioavailability and plant response. Contrariwise, the distribution strategy (single vs. split application seems to produce significant differences both in plant growth and metal uptake, but not in soil metal bioavailability. The proposed models may help to understand and predict the chelate dose – effect relationship with less experimental work.

  14. Modelling chelate-Induced phytoextraction: functional models predicting bioavailability of metals in soil, metal uptake and shoot biomass

    Directory of Open Access Journals (Sweden)

    Pasqualina Sacco

    Full Text Available Chelate-induced phytoextraction of heavy metals from contaminated soils requires special care to determine, a priori, the best method of chelate application, in terms of both dose and timing. In fact, the chelate dose must assure the bioavailability of the metal to the plant without increasing leaching risk and giving toxic effects. Three mathematical models are here proposed for usefully interpreting the processes taking place: a increased soil bioavailability of metals by chelants; b metal uptake by plants; c variation in plant biomass. The models are implemented and validated using data from pot and lysimeter trials. Both the chelate dose and the time elapsed since its application affected metal bioavailability and plant response. Contrariwise, the distribution strategy (single vs. split application seems to produce significant differences both in plant growth and metal uptake, but not in soil metal bioavailability. The proposed models may help to understand and predict the chelate dose – effect relationship with less experimental work.

  15. Metal chelate process to remove pollutants from fluids

    Science.gov (United States)

    Chang, S.G.T.

    1994-12-06

    The present invention relates to improved methods using an organic iron chelate to remove pollutants from fluids, such as flue gas. Specifically, the present invention relates to a process to remove NO[sub x] and optionally SO[sub 2] from a fluid using a metal ion (Fe[sup 2+]) chelate wherein the ligand is a dimercapto compound wherein the --SH groups are attached to adjacent carbon atoms (HS--C--C--SH) or (SH--C--CCSH) and contain a polar functional group so that the ligand of DMC chelate is water soluble. Alternatively, the DMC is covalently attached to a water insoluble substrate such as a polymer or resin, e.g., polystyrene. The chelate is regenerated using electroreduction or a chemical additive. The dimercapto compound bonded to a water insoluble substrate is also useful to lower the concentration or remove hazardous metal ions from an aqueous solution. 26 figures.

  16. Metal-chelating active packaging film enhances lysozyme inhibition of Listeria monocytogenes.

    Science.gov (United States)

    Roman, Maxine J; Decker, Eric A; Goddard, Julie M

    2014-07-01

    Several studies have demonstrated that metal chelators enhance the antimicrobial activity of lysozyme. This study examined the effect of metal-chelating active packaging film on the antimicrobial activity of lysozyme against Listeria monocytogenes. Polypropylene films were surface modified by photoinitiated graft polymerization of acrylic acid (PP-g-PAA) from the food contact surface of the films to impart chelating activity based on electrostatic interactions. PP-g-PAA exhibited a carboxylic acid density of 113 ± 5.4 nmol cm(-2) and an iron chelating activity of 53.7 ± 9.8 nmol cm(-2). The antimicrobial interaction of lysozyme and PP-g-PAA depended on growth media composition. PP-g-PAA hindered lysozyme activity at low ionic strength (2.48-log increase at 64.4 mM total ionic strength) and enhanced lysozyme activity at moderate ionic strength (5.22-log reduction at 120 mM total ionic strength). These data support the hypothesis that at neutral pH, synergy between carboxylate metal-chelating films (pKa(bulk) 6.45) and lysozyme (pI 11.35) is optimal in solutions of moderate to high ionic strength to minimize undesirable charge interactions, such as lysozyme absorption onto film. These findings suggest that active packaging, which chelates metal ions based on ligand-specific interactions, in contrast to electrostatic interactions, may improve antimicrobial synergy. This work demonstrates the potential application of metal-chelating active packaging films to enhance the antimicrobial activity of membrane-disrupting antimicrobials, such as lysozyme.

  17. A review of pitfalls and progress in chelation treatment of metal poisonings.

    Science.gov (United States)

    Andersen, Ole; Aaseth, Jan

    2016-12-01

    Most acute and chronic human metal poisonings are due to oral or inhalation exposure. Almost 80% of published animal experiments on chelation in metal poisoning used single or repeated intraperitoneal, intramuscular or intravenous administration of metal and chelator, impeding extrapolation to clinical settings. Intramuscular administration of dimercaptopropanol (BAL) has until now been used in acute arsenic, lead, and mercury poisonings, but repeated BAL administration increased the brain uptake of As, Pb and Hg in experimental animals. Also, diethyl dithiocarbamate (DDC) has been used as antidote in acute experimental animal parenteral Cd poisoning, and both DDC and tetraethylthiuram disulfide (TTD, disulfiram, Antabuse) have been used in nickel allergic patients. However, even one dose of DDC given immediately after oral Cd or Ni increased their brain uptake considerably. The calcium salt of ethylenediamminetetraacetic acid (CaEDTA) but not dimercaptosuccinic acid (DMSA) increased the brain uptake of Pb. In oral Cd or Hg poisoning, early oral administration of DMSA or dimercaptopropane sulfonate (DMPS) increased survival and reduced intestinal metal uptake. Oral administration of Prussian Blue or resins with fixed chelating groups that are not absorbed offer chelation approaches for decorporation after oral exposure to various metals. Diethylenetriaminepentaacetic acid (DTPA) nebulizers for pulmonary chelation after inhalation exposure need further development. Also, combined chelation with more than one compound may offer extensive advances. Solid knowledge on the chemistry of metal chelates together with relevant animal experiments should guide development of chelation procedures to alleviate and not aggravate the clinical status of poisoned patients. Copyright © 2016 Elsevier GmbH. All rights reserved.

  18. Selective chelation-supercritical fluid extraction of metal ions from waste materials

    International Nuclear Information System (INIS)

    Wai, C.N.; Laintz, K.E.; Yonker, C.R.

    1993-01-01

    The removal of toxic organics, metals, and radioisotopes from solids or liquids is a major concern in the treatment of industrial and nuclear wastes. For this reason, developing methods for selective separation of toxic metals and radioactive materials from solutions of complex matrix is an important problem in environmental research. Recent developments indicate supercritical fluids are good solvents for organic compounds. Many gases become supercritical fluids under moderate temperatures and pressures. For example, the critical temperature and pressure of carbon dioxide are 31 degrees C and 73 atm, respectively. The high diffusivity, low viscosity, and T-P dependence of solvent strength are some attractive properties of supercritical fluid extraction (SFE). Since CO 2 offers the additional benefits of stability and non-toxicity, the SFE technique avoids generation of organic liquid waste and exposure of personnel to toxic solvents. While direct extraction of metal ions by supercritical fluids is highly inefficient, these ions when complexed with organic ligands become quite soluble in supercritical fluids. Specific ligands can be used to achieve selective extraction of metal ions in this process. After SFE, the fluid phase can be depressurized for precipitation of the metal chelates and recycled. The ligand can also be regenerated for repeated use. The success of this selective chelation-supercritical fluid extraction (SC-SFE) process depends on a number of factors including the efficiencies of the selective chelating agents, solubilities of metal chelates in supercritical fluids, rate of extraction, ease of regeneration of the ligands, etc. In this report, the authors present recent results on the studies of the solubilities of metal chelates in supercritical CO 2 , experimental ions from aqueous solution, and the development of selective chelating agents (ionizable crown ethers) for the extraction of lanthanides and actinides

  19. The preparation and characterization of novel human-like collagen metal chelates

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Chenhui; Sun, Yan [Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering Northwest University, Xi' an 710069 (China); Shaanxi R and D Center of Biomaterials and Fermentation Engineering, Xi' an 710069 (China); Wang, Yaoyu [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Xi' an 710069 (China); Luo, Yane, E-mail: luoyane@nwu.edu.cn [Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering Northwest University, Xi' an 710069 (China); Shaanxi R and D Center of Biomaterials and Fermentation Engineering, Xi' an 710069 (China); Fan, Daidi, E-mail: fandaidi@nwu.edu.cn [Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering Northwest University, Xi' an 710069 (China); Shaanxi R and D Center of Biomaterials and Fermentation Engineering, Xi' an 710069 (China)

    2013-07-01

    In order to develop the nutritional trace elements which could be absorbed and utilized effectively, protein chelates were adopted. Calcium, copper and manganese were considered based on their physiological functions, and the new chelates of HLC-Ca, HLC-Cu and HLC-Mn were formed in MOPS or MES buffer and purified by gel chromatography, and then freeze-dried. And they were detected and analyzed by atomic absorption spectrophotometry, ultraviolet–visible absorption (UV–vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence quenching method, circular dichroism (CD) and differential scanning calorimetry (DSC). The results showed that some chemical reactions happened between HLC and the three metal ions to form new chemical compounds. The thermodynamic parameters, ∆H, ∆G and ∆S, showed that the chelation process between HLC and metal ions was performed spontaneously. Fluorescence quenching spectra of HLC indicated that the quenching mechanism was static in nature. According to the data of DSC, the new chelates were more stable than the free HLC. And HLC-metal complex was non-toxic to the BHK21 cell through MTT assay. - Highlights: ► HLC-Ca, HLC-Cu and HLC-Mn were new chemical compounds and different to free HLC. ► Possible sites for Ca{sup 2+}, Cu{sup 2+} and Mn{sup 2+} to bind with HLC were presented. ► The chelation process between HLC and metal ions was performed spontaneously. ► The thermodynamic stability of the new chelates was higher than that of free HLC.

  20. Photo-Curable Metal-Chelating Coatings Offer a Scalable Approach to Production of Antioxidant Active Packaging.

    Science.gov (United States)

    Lin, Zhuangsheng; Goddard, Julie

    2018-02-01

    Synthetic metal chelators (for example, ethylenediaminetetraacetic acid, EDTA) are widely used as additives to control trace transition metal induced oxidation in consumer products. To enable removal of synthetic chelators in response to increasing consumer demand for clean label products, metal-chelating active food packaging technologies have been developed with demonstrated antioxidant efficacy in simulated food systems. However, prior work in fabrication of metal-chelating materials leveraged batch chemical reactions to tether metal-chelating ligands, a process with limited industrial translatability for large-scale fabrication. To improve the industrial translatability, we have designed a 2-step laminated photo-grafting process to introduce metal chelating functionality onto common polymeric packaging materials. Iminodiacetic acid (IDA) functionalized materials were fabricated by photo-grafting poly(acrylic acid) onto polypropylene (PP) films, followed by a second photo-grafting process to graft-polymerize an IDA functionalized vinyl monomer (GMA-IDA). The photo-grafting was conducted under atmospheric conditions and was completed in 2 min. The resulting IDA functionalized metal-chelating material was able to chelate iron and copper, and showed antioxidant efficacy against ascorbic acid degradation, supporting its potential to be used synergistically with natural antioxidants for preservation of food and beverage products. The 2-step photo-grafting process improves the throughput of active packaging coatings, enabling potential roll-to-roll fabrication of metal-chelating active packaging materials for antioxidant food packaging applications. To address consumer and retail demands for "clean label" foods and beverages without a corresponding loss in product quality and shelf life, producers are seeking next generation technologies such as active packaging. In this work, we will report the synthesis of metal-chelating active packaging films, which enable removal

  1. Targeted Catalytic Inactivation of Angiotensin Converting Enzyme by Lisinopril-Coupled Transition Metal Chelates

    Science.gov (United States)

    Joyner, Jeff C.; Hocharoen, Lalintip; Cowan, J. A.

    2012-01-01

    A series of compounds that target reactive transition metal chelates to somatic Angiotensin Converting Enzyme (sACE-1) have been synthesized. Half maximal inhibitory concentrations (IC50) and rate constants for both inactivation and cleavage of full length sACE-1 have been determined and evaluated in terms of metal-chelate size, charge, reduction potential, coordination unsaturation, and coreactant selectivity. Ethylenediamine-tetraacetic acid (EDTA), nitrilotriacetic acid (NTA), 1,4,7,10-tetraazacyclo-dodecane-1,4,7,10-tetraacetic acid (DOTA), and tripeptide GGH were linked to the lysine sidechain of lisinopril by EDC/NHS coupling. The resulting amide-linked chelate-lisinopril (EDTA-lisinopril, NTA-lisinopril, DOTA-lisinopril, and GGH-lisinopril) conjugates were used to form coordination complexes with iron, cobalt, nickel and copper, such that lisinopril could mediate localization of the reactive metal chelates to sACE-1. ACE activity was assayed by monitoring cleavage of the fluorogenic substrate Mca-RPPGFSAFK(Dnp)-OH, a derivative of bradykinin, following pre-incubation with metal-chelate-lisinopril compounds. Concentration-dependent inhibition of sACE-1 by metal-chelate-lisinopril complexes revealed IC50 values ranging from 44 nM to 4,500 nM for Ni-NTA-lisinopril and Ni-DOTA-lisinopril, respectively, versus 1.9 nM for lisinopril. Stronger inhibition was correlated with smaller size and lower negative charge of the attached metal chelates. Time-dependent inactivation of sACE-1 by metal-chelate-lisinopril complexes revealed a remarkable range of catalytic activities, with second order rate constants as high as 150,000 M−1min−1 (Cu-GGH-lisinopril), while catalyst-mediated cleavage of sACE-1 typically occurred at much lower rates, indicating that inactivation arose primary from sidechain modification. Optimal inactivation of sACE-1 was observed when the reduction potential for the metal center was poised near 1000 mV, reflecting the difficulty of protein

  2. Targeted catalytic inactivation of angiotensin converting enzyme by lisinopril-coupled transition-metal chelates.

    Science.gov (United States)

    Joyner, Jeff C; Hocharoen, Lalintip; Cowan, J A

    2012-02-22

    A series of compounds that target reactive transition-metal chelates to somatic angiotensin converting enzyme (sACE-1) have been synthesized. Half-maximal inhibitory concentrations (IC(50)) and rate constants for both inactivation and cleavage of full-length sACE-1 have been determined and evaluated in terms of metal chelate size, charge, reduction potential, coordination unsaturation, and coreactant selectivity. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), and tripeptide GGH were linked to the lysine side chain of lisinopril by 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride/N-hydroxysuccinimide coupling. The resulting amide-linked chelate-lisinopril (EDTA-lisinopril, NTA-lisinopril, DOTA-lisinopril, and GGH-lisinopril) conjugates were used to form coordination complexes with iron, cobalt, nickel, and copper, such that lisinopril could mediate localization of the reactive metal chelates to sACE-1. ACE activity was assayed by monitoring cleavage of the fluorogenic substrate Mca-RPPGFSAFK(Dnp)-OH, a derivative of bradykinin, following preincubation with metal chelate-lisinopril compounds. Concentration-dependent inhibition of sACE-1 by metal chelate-lisinopril complexes revealed IC(50) values ranging from 44 to 4500 nM for Ni-NTA-lisinopril and Ni-DOTA-lisinopril, respectively, versus 1.9 nM for lisinopril. Stronger inhibition was correlated with smaller size and lower negative charge of the attached metal chelates. Time-dependent inactivation of sACE-1 by metal chelate-lisinopril complexes revealed a remarkable range of catalytic activities, with second-order rate constants as high as 150,000 M(-1) min(-1) (Cu-GGH-lisinopril), while catalyst-mediated cleavage of sACE-1 typically occurred at much lower rates, indicating that inactivation arose primarily from side chain modification. Optimal inactivation of sACE-1 was observed when the reduction potential for the

  3. Comparison of natural organic acids and synthetic chelates at enhancing phytoextraction of metals from a multi-metal contaminated soil

    International Nuclear Information System (INIS)

    Clistenes do Nascimento, Williams A.; Amarasiriwardena, Dula; Xing, Baoshan

    2006-01-01

    Chemically assisted phytoremediation has been developing to induce accumulation of metals by high biomass plants. Synthetic chelates have shown high effectiveness to reach such a goal, but they pose serious drawbacks in field application due to the excessive amount of metals solubilized. We compared the performance of synthetic chelates with naturally occurring low molecular weight organic acids (LMWOA) in enhancing phytoextraction of metals by Indian mustard (Brassica juncea) from multi-metal contaminated soils. Gallic and citric acids were able to induce removal of Cd, Zn, Cu, and Ni from soil without increasing the leaching risk. Net removal of these metals caused by LMWOA can be as much as synthetic chelates. A major reason for this is the lower phytotoxicity of LMWOA. Furthermore, supplying appropriate mineral nutrients increased biomass and metal removal. - Organic acids can be as efficient as synthetic chelates for use in phytoextraction of multi-metal contaminated soils

  4. Chelating capture and magnetic removal of non-magnetic heavy metal substances from soil

    Science.gov (United States)

    Fan, Liren; Song, Jiqing; Bai, Wenbo; Wang, Shengping; Zeng, Ming; Li, Xiaoming; Zhou, Yang; Li, Haifeng; Lu, Haiwei

    2016-02-01

    A soil remediation method based on magnetic beneficiation is reported. A new magnetic solid chelator powder, FS@IDA (core-shell Fe3O4@SiO2 nanoparticles coated with iminodiacetic acid chelators), was used as a reactive magnetic carrier to selectively capture non-magnetic heavy metals in soil by chelation and removal by magnetic separation. FS@IDA was prepared via inorganic-organic and organic synthesis reactions that generated chelating groups on the surface of magnetic, multi-core, core-shell Fe3O4@SiO2 (FS) nanoparticles. These reactions used a silane coupling agent and sodium chloroacetate. The results show that FS@IDA could chelate the heavy metal component of Cd, Zn, Pb, Cu and Ni carbonates, lead sulfate and lead chloride in water-insoluble salt systems. The resulting FS@IDA-Cd and FS@IDA-Pb chelates could be magnetically separated, resulting in removal rates of approximately 84.9% and 72.2% for Cd and Pb, respectively. FS@IDA could not remove the residual heavy metals and those bound to organic matter in the soil. FS@IDA did not significantly alter the chemical composition of the soil, and it allowed for fast chelating capture, simple magnetic separation and facilitated heavy metal elution. FS@IDA could also be easily prepared and reprocessed.

  5. Heavy Metal Displacement in Chelate-Assisted Phytoremediation of Biosolids Soil

    Science.gov (United States)

    Kirkham, M. B.; Liphadzi, M. S.

    2005-05-01

    Heavy metals in biosolids (sewage sludge) applied to land contaminate the soil. Phytoremediation, the use of plants to clean up toxic heavy metals, might remove them. Chelating agents are added to soil to solubilize the metals for enhanced phytoextraction. Yet no studies follow the displacement and leaching of heavy metals in soil with biosolids following solubilization with chelates. The objective of this work was to determine the mobility of heavy metals, as affected by a chelate, in soil (Haynie very fine sandy loam) from a 25-year old sludge farm. Soil columns (105 cm long; 39 cm in diameter) either had a plant (hybrid poplar; Populus deltoides Marsh. x P. nigra L.) or no plant. When the poplars were 144 days old, the tetrasodium salt of the chelating agent EDTA (ethylenediamine-tetraacetic acid) was irrigated onto the soil at a rate of 1 g per kg of soil. Drainage water, soil, and plants were analyzed for three toxic heavy metals (Cd, Ni, Pb) and four essential heavy metals (Cu, Fe, Mn, Zn). Without EDTA, concentrations of the seven heavy metals in the leachate from columns with or without plants were low or below detection limits. With or without plants, the EDTA mobilized all heavy metals and increased their concentration in drainage water. Without plants, the concentrations of Cd, Cu, Fe, Pb, and Zn in the leachate from columns with EDTA were above drinking-water standards. (There is no drinking-water standard for Ni.) The presence of poplar plants in the soil reduced the concentrations of Cu, Fe, and Zn in the leachate so it fell within drinking-water standards. Concentrations of Cd and Pb in the leachate remained above drinking-water standards with or without plants. At harvest (124 days after the EDTA application), total concentration of each heavy metal in the soil at different depths in the columns with EDTA was similar to that in the columns without EDTA. The chelate did not affect the concentration of heavy metals in the roots, stems, or leaves

  6. High precision isotopic ratio analysis of volatile metal chelates

    International Nuclear Information System (INIS)

    Hachey, D.L.; Blais, J.C.; Klein, P.D.

    1980-01-01

    High precision isotope ratio measurements have been made for a series of volatile alkaline earth and transition metal chelates using conventional GC/MS instrumentation. Electron ionization was used for alkaline earth chelates, whereas isobutane chemical ionization was used for transition metal studies. Natural isotopic abundances were determined for a series of Mg, Ca, Cr, Fe, Ni, Cu, Cd, and Zn chelates. Absolute accuracy ranged between 0.01 and 1.19 at. %. Absolute precision ranged between +-0.01-0.27 at. % (RSD +- 0.07-10.26%) for elements that contained as many as eight natural isotopes. Calibration curves were prepared using natural abundance metals and their enriched 50 Cr, 60 Ni, and 65 Cu isotopes covering the range 0.1-1010.7 at. % excess. A separate multiple isotope calibration curve was similarly prepared using enriched 60 Ni (0.02-2.15 at. % excess) and 62 Ni (0.23-18.5 at. % excess). The samples were analyzed by GC/CI/MS. Human plasma, containing enriched 26 Mg and 44 Ca, was analyzed by EI/MS. 1 figure, 5 tables

  7. Spectroscopy, modeling and computation of metal chelate solubility in supercritical CO2

    International Nuclear Information System (INIS)

    Brennecke, J.F.; Stadtherr, M.A.

    1999-01-01

    The overall objectives of this project were to gain a fundamental understanding of the solubility and phase behavior of metal chelates in supercritical CO 2 . Extraction with CO 2 is an excellent way to remove organic compounds from soils, sludges and aqueous solutions, and recent research has demonstrated that, together with chelating agents, it is a viable way to remove metals, as well. In this project the authors sought to gain fundamental knowledge that is vital to computing phase behavior, and modeling and designing processes using CO 2 to separate organics and metal compounds from DOE mixed wastes. The overall program was a comprehensive one to measure, model and compute the solubility of metal chelate complexes in supercritical CO 2 and CO 2 /cosolvent mixtures. Through a combination of phase behavior measurements, spectroscopy and the development of a new computational technique, the authors have achieved a completely reliable way to model metal chelate solubility in supercritical CO 2 and CO 2 /co-contaminant mixtures. Thus, they can now design and optimize processes to extract metals from solid matrices using supercritical CO 2 , as an alternative to hazardous organic solvents that create their own environmental problems, even while helping in metals decontamination

  8. Phytoremediation of metals contaminated dredged sediments: Use of synthetic chelates in metals phytoextraction

    Science.gov (United States)

    Sahut, C.; Geniaut, G.; Lillo, M. P.

    2003-05-01

    (in Times 10 points) The waterways maintenance leads to a large volume of dredged polluted sediments, to be disposed of, every year. As the economic disposal of dredged sediment is a single line along the stream they can behave as a sink of pollutant and a migration in the environment is observed. Chelate-enhanced phytoremediation has been proposed as an effective tool for the extraction of heavy metals from dredged sediment by plants. Lysimeters studies were conducted to study the phytoremediation of sediments with EDTA and lactic acid used as synthetic chelators. EDTA appeared to enhance metal solubility by plant uptake did not increase accordingly. Futhermore EDTA enhance metal leaching which could lead 10 groungwater pollution. To prevent these unwanted side-effects, careful management of phytoremediation and of the use of EDTA seems necessary.

  9. Metal chelates of some transition and non-transition metal ions with Schiff base derived from isatin with o-phenylenediamine

    International Nuclear Information System (INIS)

    Hassaan, A.M.A.; Khalifa, M.A.

    1993-01-01

    New Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) chelates of the Schiff base derived from isatin with o-phenylenediamine have been synthesized and characterized on the basis of elemental analyses, electronic, IR and 1 H NMR spectra, and also by aid of molar conductivity and magnetic moment measurements. It has been found that the Schiff base behaves as ONNO tetradentate dibasic ligand forming chelates with 1:1 (metal:ligand) stoichiometry. Square planar environment is suggested for nickel(II) chelate. All the metal chelates show non-electrolytic behaviour

  10. Spectroscopy, modeling and computation of metal chelate solubility in supercritical CO2. 1998 annual progress report

    International Nuclear Information System (INIS)

    Brennecke, J.F.; Chateauneuf, J.E.; Stadtherr, M.A.

    1998-01-01

    'This report summarizes work after 1 year and 8 months (9/15/96-5/14/98) of a 3 year project. Thus far, progress has been made in: (1) the measurement of the solubility of metal chelates in SC CO 2 with and without added cosolvents, (2) the spectroscopic determination of preferential solvation of metal chelates by cosolvents in SC CO 2 solutions, and (3) the development of a totally reliable computational technique for phase equilibrium computations. An important factor in the removal of metals from solid matrices with CO 2 /chelate mixtures is the equilibrium solubility of the metal chelate complex in the CO 2 .'

  11. Metal-chelating compounds produced by ectomycorrhizal fungi collected from pine plantations.

    Science.gov (United States)

    Machuca, A; Pereira, G; Aguiar, A; Milagres, A M F

    2007-01-01

    To investigate the in vitro production of metal-chelating compounds by ectomycorrhizal fungi collected from pine plantations in southern Chile. Scleroderma verrucosum, Suillus luteus and two isolates of Rhizopogon luteolus were grown in solid and liquid modified Melin-Norkans (MMN) media with and without iron addition and the production of iron-chelating compounds was determined by Chrome Azurol S (CAS) assay. The presence of hydroxamate and catecholate-type compounds and organic acids was also investigated in liquid medium. All isolates produced iron-chelating compounds as detected by CAS assay, and catecholates, hydroxamates as well as oxalic, citric and succinic acids were also detected in all fungal cultures. Scleroderma verrucosum produced the greatest amounts of catecholates and hydroxamates whereas the highest amounts of organic acids were detected in S. luteus. Nevertheless, the highest catecholate, hydroxamate and organic acid concentrations did not correlate with the highest CAS reaction which was observed in R. luteolus (Yum isolate). Ectomycorrhizal fungi produced a variety of metal-chelating compounds when grown in liquid MMN medium. However, the addition of iron to all fungi cultures reduced the CAS reaction, hydroxamate and organic acid concentrations. Catecholate production was affected differently by iron, depending on the fungal isolate. The ectomycorrhizal fungi described in this study have never been reported to produce metal-chelating compound production. Moreover, apart from some wood-rotting fungi, this is the first evidence of the presence of catecholates in R. luteolus, S. luteus and S. verrucosum cultures.

  12. Micronutrient metal speciation is controlled by competitive organic chelation in grassland soils

    Energy Technology Data Exchange (ETDEWEB)

    Boiteau, Rene M.; Shaw, Jared B.; Pasa Tolic, Ljiljana; Koppenaal, David W.; Jansson, Janet K.

    2018-05-01

    Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or how they interact and compete for metal binding. Identifying these metallo-organic species within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrix. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) from Kansas Prairie soil. Both plant and fungal chelators were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant iron acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamine, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-57 pmol / g soil). In contrast, the fungal siderophore ferricrocine bound comparatively more trivalent Fe (9pmol / g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population. Even small structural differences

  13. Preparation and Properties of the Chitosan/PVA Blend for Heavy Metals Chelation

    Directory of Open Access Journals (Sweden)

    Zuhair Jabbar Abdul Ameer

    2016-09-01

    Full Text Available Current research based on the use of extracted chitosan mixed with Polyvinyl alcohol to manufacture blend that can been used in water purification from heavy metals such as copper, this due to chitosan properties and its ability to chelation these metals because of the presence of the functional groups in their structure. The blend has been treated with borax to increase the viscosity, and then high density polyethylene granulated coated with polymer solution to increase the surface area for chelation. The ultraviolet test showed the efficiency of blend to chelation of copper ions through lower the copper ions absorbance peak after each stage where the solution of copper ions pass on the polymer blend containing chitosan.

  14. Micronutrient metal speciation is driven by competitive organic chelation in grassland soils.

    Science.gov (United States)

    Boiteau, R.; Shaw, J. B.; Paša-Tolić, L.; Koppenaal, D.; Jansson, J.

    2017-12-01

    Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or how they interact and compete for metal binding. Identifying these metallo-organic species within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrix. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) from Kansas Prairie soil. Both plant and fungal chelators were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant iron acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamine, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-57 pmol / g soil). In contrast, the fungal siderophore ferricrocine bound comparatively more trivalent Fe (9pmol / g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population.

  15. Jacks of metal(loid chelation trade in plants – an overview

    Directory of Open Access Journals (Sweden)

    Naser A. Anjum

    2015-04-01

    Full Text Available Varied environmental compartments including soils are being contaminated by a myriad toxic metal(loids (hereafter termed as ‘metal/s’ mainly through anthropogenic activities. These metals may contaminate food chain and bring irreparable consequences in human. Plant-based approach (phytoremediation stands second to none among bioremediation technologies meant for sustainable cleanup of soils/sites with metal-contamination. In turn, the capacity of plants to tolerate potential consequences caused by the extracted/accumulated metals decides the effectiveness and success of phytoremediation system. Chelation is among the potential mechanisms that largely govern metal-tolerance in plant cells by maintaining low concentrations of free metals in cytoplasm. Metal-chelation can be performed by compounds of glutathione (GSH (reduced GSH; phytochelatins, PCs; metallothioneins, MTs and non-GSH (histidine, nicotianamine, organic acids origin. This paper presents an appraisal of recent reports on both GSH and non-GSH associated compounds in an effort to shed light on the significance of these compounds in metal-plant tolerance, as well as to provide scientific clues for the development of phytoextraction strategies.

  16. Chelation Therapy for Mercury Poisoning

    Directory of Open Access Journals (Sweden)

    Rong Guan

    2009-01-01

    Full Text Available Chelation therapy has been the major treatment for heavy metal poisoning. Various chelating agents have been developed and tested for treatment of heavy metal intoxications, including mercury poisoning. It has been clearly shown that chelating agents could rescue the toxicity caused by heavy metal intoxication, but the potential preventive role of chelating agents against heavy metal poisoning has not been explored much. Recent paper by Siddiqi and colleagues has suggested a protective role of chelating agents against mercury poisoning, which provides a promising research direction for broader application of chelation therapy in prevention and treatment of mercury poisoning.

  17. Chemical and biological properties of toxic metals and use of chelating agents for the pharmacological treatment of metal poisoning

    Energy Technology Data Exchange (ETDEWEB)

    Sinicropi, Maria Stefania; Caruso, Anna [University of Calabria, Department of Pharmaceutical Sciences, Rende (Italy); Amantea, Diana [University of Calabria, Department of Pharmacobiology, Rende (Italy); Saturnino, Carmela [University of Salerno, Department of Pharmaceutical Sciences, Fisciano (Italy)

    2010-07-15

    Exposure to toxic metals is a well-known problem in industrialized countries. Metals interfere with a number of physiological processes, including central nervous system (CNS), haematopoietic, hepatic and renal functions. In the evaluation of the toxicity of a particular metal it is crucial to consider many parameters: chemical forms (elemental, organic or inorganic), binding capability, presence of specific proteins that selectively bind metals, etc. Medical treatment of acute and chronic metal toxicity is provided by chelating agents, namely organic compounds capable of interacting with metal ions to form structures called chelates. The present review attempts to provide updated information about the mechanisms, the cellular targets and the effects of toxic metals. (orig.)

  18. Chelating capture and magnetic removal of non-magnetic heavy metal substances from soil

    OpenAIRE

    Liren Fan; Jiqing Song; Wenbo Bai; Shengping Wang; Ming Zeng; Xiaoming Li; Yang Zhou; Haifeng Li; Haiwei Lu

    2016-01-01

    A soil remediation method based on magnetic beneficiation is reported. A new magnetic solid chelator powder, FS@IDA (core-shell Fe3O4@SiO2 nanoparticles coated with iminodiacetic acid chelators), was used as a reactive magnetic carrier to selectively capture non-magnetic heavy metals in soil by chelation and removal by magnetic separation. FS@IDA was prepared via inorganic-organic and organic synthesis reactions that generated chelating groups on the surface of magnetic, multi-core, core-shel...

  19. The use of dihexyldithiocarbamate in reverse-phase HPLC of metal chelates

    Science.gov (United States)

    Fatimah, S. S.; Bahti, H. H.; Hastiawan, I.; Permanasari, A.

    2018-05-01

    Dialkyldithiocarbamates have long been used as chelating agents in reverse-phase HPLC of transition metals. In the previous study, an alkyl homolog of this type of ligand, namely dihexyldithiocarbamate (DHDTC), was synthesized and characterized. The use of this particular ligand in the revese-phase HPLC of some selected transition metal ions is now reported for the first time. The mobile phase comprising of the flow rate and of the detection, in the separation of the metal chelates of Cd (II), Fe (III), Cu (II), and Co (III), were investigated on a C-18 column. The results showed that dihexylditiocarbamate could be used for separating Cd (II), Fe(III), Cu(II), and Co(III). Therefore, it could be used in simultaneous analysis.

  20. Chronic Toxic Metal Exposure and Cardiovascular Disease: Mechanisms of Risk and Emerging Role of Chelation Therapy.

    Science.gov (United States)

    Aneni, Ehimen C; Escolar, Esteban; Lamas, Gervasio A

    2016-12-01

    Over the last few decades, there has been a growing body of epidemiologic evidence linking chronic toxic metal exposure to cardiovascular disease-related morbidity and mortality. The recent and unexpectedly positive findings from a randomized, double-blind, multicenter trial of metal chelation for the secondary prevention of atherosclerotic cardiovascular disease (Trial to Assess Chelation Therapy (TACT)) have focused the discussion on the role of chronic exposure to toxic metals in the development and propagation of cardiovascular disease and the role of toxic metal chelation therapy in the secondary prevention of cardiovascular disease. This review summarizes the most recent evidence linking chronic toxic metal exposure to cardiovascular disease and examines the findings of TACT.

  1. Chelation Therapy for Mercury Poisoning

    OpenAIRE

    Rong Guan; Han Dai

    2009-01-01

    Chelation therapy has been the major treatment for heavy metal poisoning. Various chelating agents have been developed and tested for treatment of heavy metal intoxications, including mercury poisoning. It has been clearly shown that chelating agents could rescue the toxicity caused by heavy metal intoxication, but the potential preventive role of chelating agents against heavy metal poisoning has not been explored much. Recent paper by Siddiqi and colleagues has suggested a protective role o...

  2. DFT study of the interaction between DOTA chelator and competitive alkali metal ions.

    Science.gov (United States)

    Frimpong, E; Skelton, A A; Honarparvar, B

    2017-09-01

    1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetracetic acid (DOTA) is an important chelator for radiolabeling of pharmaceuticals. The ability of alkali metals found in the body to complex with DOTA and compete with radio metal ions can alter the radiolabeling process. Non-covalent interactions between DOTA complexed with alkali metals Li + , Na + , K + and Rb + , are investigated with density functional theory using B3LYP and ωB97XD functionals. Conformational possibilities of DOTA were explored with a varying number of carboxylic pendant arms of DOTA in close proximity to the ions. It is found that the case in which four arms of DOTA are interacting with ions is more stable than other conformations. The objective of this study is to explore the electronic structure properties upon complexation of alkali metals Li + Na + , K + and Rb + with a DOTA chelator. Interaction energies, relaxation energies, entropies, Gibbs free energies and enthalpies show that the stability of DOTA, complexed with alkali metals decreases down the group of the periodic table. Implicit water solvation affects the complexation of DOTA-ions leading to decreases in the stability of the complexes. NBO analysis through the natural population charges and the second order perturbation theory, revealed a charge transfer between DOTA and alkali metals. Conceptual DFT-based properties such as HOMO/LUMO energies, ΔE HOMO-LUMO and chemical hardness and softness indicated a decrease in the chemical stability of DOTA-alkali metal complexes down the alkali metal series. This study serves as a guide to researchers in the field of organometallic chelators, particularly, radiopharmaceuticals in finding the efficient optimal match between chelators and various metal ions. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Polymeric metal chelates with piperazine(bis)dithiocarbamate

    International Nuclear Information System (INIS)

    Larionov, S.V.; Kosareva, L.A.; Ikorskij, V.N.; Uskov, E.M.

    1982-01-01

    Roentgenoamorphous polymer chelates of Fe 3 , Co 2 , Ni 2 , Cu 2 , Zn 2 , Cd 2 , Pb 2 with tetradentate bridge ligand piperazine-(bis) dithiocarbamate have been synthesized. IR spectra in the region 200-400 cm - 1 point to coordination of sulphur atoms of groups CS 2- with metals. It is found that among the polymers synthesized CuLxH 2 O possesses the lowest electric resistance

  4. 24 CFR 266.638 - Issuance of HFA Debenture.

    Science.gov (United States)

    2010-04-01

    ... HOUSING FINANCE AGENCY RISK-SHARING PROGRAM FOR INSURED AFFORDABLE MULTIFAMILY PROJECT LOANS Contract... the HFA time to foreclose and/or resell the project. HUD may provide a written extension of the five year term if the HFA certifies and provides documentation that the project owner has filed bankruptcy...

  5. Effect of other metals on iron bioavailability in presence of a selective chelator

    International Nuclear Information System (INIS)

    Rehman, F.S.

    1995-01-01

    Iron (III) is generally very easily chelated by a number of chelators in the biological environment, either supplied by food or already present there. One of the these chelator is gallic acid. The stability constants of the complexes formed between gallic acid and other trace metals have been determined by a potentiometric method. The data obtained was computed with the help of computer program B est . The resulted Beta values were compared with already known values of iron gallic acid complexes. (author)

  6. Article Commentary: Chelation Therapy for Mercury Poisoning

    Directory of Open Access Journals (Sweden)

    Rong Guan

    2009-01-01

    Full Text Available Chelation therapy has been the major treatment for heavy metal poisoning. Various chelating agents have been developed and tested for treatment of heavy metal intoxications, including mercury poisoning. It has been clearly shown that chelating agents could rescue the toxicity caused by heavy metal intoxication, but the potential preventive role of chelating agents against heavy metal poisoning has not been explored much. Recent paper by Siddiqi and colleagues has suggested a protective role of chelating agents against mercury poisoning, which provides a promising research direction for broader application of chelation therapy in prevention and treatment of mercury poisoning.

  7. N-Acetyl-Cysteine as Effective and Safe Chelating Agent in Metal-on-Metal Hip-Implanted Patients: Two Cases

    Directory of Open Access Journals (Sweden)

    Andrea Giampreti

    2016-01-01

    Full Text Available Systemic toxicity associated with cobalt (Co and chromium (Cr containing metal hip alloy may result in neuropathy, cardiomyopathy, and hypothyroidism. However clinical management concerning chelating therapy is still debated in literature. Here are described two metal-on-metal hip-implanted patients in which N-acetyl-cysteine decreased elevated blood metal levels. A 67-year-old male who underwent Co/Cr hip implant in September 2009 referred to our Poison Control Centre for persisting elevated Co/Cr blood levels (from March 2012 to November 2014. After receiving oral high-dose N-acetyl-cysteine, Co/Cr blood concentrations dropped by 86% and 87% of the prechelation levels, respectively, and persisted at these latter concentrations during the following 6 months of follow-up. An 81-year-old female who underwent Co/Cr hip implant in January 2007 referred to our Centre for detection of high Co and Cr blood levels in June 2012. No hip revision was indicated. After a therapy with oral high-dose N-acetyl-cysteine Co/Cr blood concentrations decreased of 45% and 24% of the prechelation levels. Chelating agents reported in hip-implanted patients (EDTA, DMPS, and BAL are described in few cases. N-acetyl-cysteine may provide chelating sites for metals and in our cases reduced Co and Cr blood levels and resulted well tolerable.

  8. Effect of the chelation of metal cation on the antioxidant activity of chondroitin sulfates.

    Science.gov (United States)

    Ajisaka, Katsumi; Oyanagi, Yutaka; Miyazaki, Tatsuo; Suzuki, Yasuhiro

    2016-06-01

    The antioxidant potencies of chondroitin sulfates (CSs) from shark cartilage, salmon cartilage, bovine trachea, and porcine intestinal mucosa were compared by three representative methods for the measurement of the antioxidant activity; DPPH radical scavenging activity, superoxide radical scavenging activity, and hydroxyl radical scavenging activity. CSs from salmon cartilage and bovine trachea showed higher potency in comparison with CSs from shark cartilage and porcine intestinal mucosa. Next, CS from salmon cartilage chelating with Ca(2+), Mg(2+), Mn(2+), or Zn(2+) were prepared, and their antioxidant potencies were compared. CS chelating with Ca(2+) or Mg(2+) ions showed rather decreased DPPH radical scavenging activity in comparison with CS of H(+) form. In contrast, CS chelating with Ca(2+) or Mg(2+) ion showed remarkably enhanced superoxide radical scavenging activity than CS of H(+) or Na(+) form. Moreover, CS chelating with divalent metal ions, Ca(2+), Mg(2+), Mn(2+), or Zn(2+), showed noticeably higher hydroxyl radical scavenging activity than CS of H(+) or Na(+) form. The present results revealed that the scavenging activities of, at least, superoxide radical and hydroxyl radical were enhanced by the chelation with divalent metal ions.

  9. [Enhanced phytoextraction of heavy metal contaminated soil by chelating agents and auxin indole-3-acetic acid].

    Science.gov (United States)

    Zhou, Jian-min; Dang, Zhi; Chen, Neng-chang; Xu, Sheng-guang; Xie, Zhi-yi

    2007-09-01

    The environmental risk of chelating agents such as EDTA application to the heavy metals polluted soils and the stress on plant roots due to the abrupt increase metals concentration limit the wide commercial use of chelate-induced phytoextraction. Chelating agent ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) and auxin indole-3-acetic acid (IAA) were used for enhancing heavy metals uptake from soils by Zea mays L. (corn) in pot experiments. The metals content in plant tissues was quantified using an inductively coupled plasma mass spectrometer (ICP-MS). The results showed that the combination of IAA and EDTA increased the biomass by about 40.0% and the contents of Cu, Zn, Cd and Pb in corn shoots by 27.0%, 26.8%, 27.5% and 32.8% respectively, as compared to those in EDTA treatment. While NTA&IAA treatment increased the biomass by about 29.9% and the contents of Cu, Zn, Cd and Pb in corn shoots by 31.8%, 27.6%, 17.0% and 26.9% respectively, as compared to those in NTA treatment. These results indicated that corn growth was promoted, and the biomass and the accumulation of heavy metals in plant shoots were increased significantly with the addition of IAA, which probably helps to change the cell membrane properties and the biomass distribution, resulting in the alleviation of the phytotoxicity of metals and the chelating agents.

  10. Isolation and characterization of iron chelators from turmeric (Curcuma longa): selective metal binding by curcuminoids.

    Science.gov (United States)

    Messner, Donald J; Surrago, Christine; Fiordalisi, Celia; Chung, Wing Yin; Kowdley, Kris V

    2017-10-01

    Iron overload disorders may be treated by chelation therapy. This study describes a novel method for isolating iron chelators from complex mixtures including plant extracts. We demonstrate the one-step isolation of curcuminoids from turmeric, the medicinal food spice derived from Curcuma longa. The method uses iron-nitrilotriacetic acid (NTA)-agarose, to which curcumin binds rapidly, specifically, and reversibly. Curcumin, demethoxycurcumin, and bisdemethoxycurcumin each bound iron-NTA-agarose with comparable affinities and a stoichiometry near 1. Analyses of binding efficiencies and purity demonstrated that curcuminoids comprise the primary iron binding compounds recovered from a crude turmeric extract. Competition of curcuminoid binding to the iron resin was used to characterize the metal binding site on curcumin and to detect iron binding by added chelators. Curcumin-Iron-NTA-agarose binding was inhibited by other metals with relative potency: (>90% inhibition) Cu 2+  ~ Al 3+  > Zn 2+  ≥ Ca 2+  ~ Mg 2+  ~ Mn 2+ (80% by addition of iron to the media; uptake was completely restored by desferoxamine. Ranking of metals by relative potencies for blocking curcumin uptake agreed with their relative potencies in blocking curcumin binding to iron-NTA-agarose. We conclude that curcumin can selectively bind toxic metals including iron in a physiological setting, and propose inhibition of curcumin binding to iron-NTA-agarose for iron chelator screening.

  11. A Metal Chelating Porous Polymeric Support: The Missing Link for a Defect-free Metal-Organic Framework Composite Membrane

    KAUST Repository

    Barankova, Eva

    2017-02-06

    Since the discovery of size-selective metal-organic frameworks (MOFs), researchers have tried to incorporate these materials into gas separation membranes. Impressive gas selectivities were found, but these MOF membranes were mostly made on inorganic supports, which are generally too bulky and expensive for industrial gas separation. Forming MOF layers on porous polymer supports is industrially attractive but technically challenging. Two features to overcome these problems are described: 1) a metal chelating support polymer to bind the MOF layer, and 2) control of MOF crystal growth by contra-diffusion, aiming at a very thin nanocrystalline MOF layer. Using a metal chelating polythiosemicarbazide (PTSC) support and adjusting the metal and organic ligand concentrations carefully, a very compact ZIF-8 (ZIF=zeolitic imidazolate framework) layer was produced that displayed interference colors because of its smooth surface and extreme thinness-within the range of visible light. High performances were measured in terms of hydrogen/propane (8350) and propylene/propane (150) selectivity.

  12. Effects of hydroxycinnamic acids on blue color expression of cyanidin derivatives and their metal chelates.

    Science.gov (United States)

    Sigurdson, G T; Robbins, R J; Collins, T M; Giusti, M M

    2017-11-01

    Mechanisms to recreate many anthocyanin blue hues in nature are not fully understood, but interactions with metal ions and phenolic compounds are thought to play important roles. Bluing effects of hydroxycinnamic acids on cyanidin and chelates were investigated by addition of the acids to triglycosylated cyanidin (0-50×[anthocyanin]) and by comparison to hydroxycinnamic acid monoacylated and diacylated Cy fractions by spectrophotometry (380-700nm) and colorimetry in pH 5-8. With no metal ions, λ max and absorbance was greatest for cyanidin with diacylation>monoacylation>increasing [acids]. Hydroxycinnamic acids added to cyanidin solutions weakly impacted color characteristics (ΔEacid attachment) resulted in ΔE 5-15. Triglycosylated cyanidin expressed blue color (pH 7-8), suggesting glycosylation pattern also plays a role. Al 3+ chelation increased absorbance 2-42× and λ max ≳40nm (pH 5-6) compared to added hydroxycinnamic acids. Metal chelation and aromatic diacylation resulted in the most blue hues. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. [Influences of the mobile phase constitution, salt concentration and pH value on retention characters of proteins on the metal chelate column].

    Science.gov (United States)

    Li, R; Di, Z M; Chen, G L

    2001-09-01

    The effects of the nature and concentration of salts, pH value and competitive eluent in the mobile phase on the protein retention have been systematically investigated. A mathematical expression describing the protein retention in metal chelate chromatography has been derived. It is proposed that the eluting power of the salt solution can be expressed by the eluent strength exponent epsilon. According to the retention characters of protein under different chromatographic conditions, the interaction between the various metal chelate ligands and proteins is discussed. The protein retention on the metal chelate column is a cooperative interactions of coordination, electrostatic and hydrophobic interaction. For the strong combined metal column with proteins such as IDA-Cu, the coordination is the most important, and the electrostatic interaction is secondary in chromatographic process. However, for the weak combined metal columns with proteins such as IDA-Ni, IDA-Co and IDA-Zn, the electrostatic interaction between the metal chelate ligands and proteins is the chief one, while the coordination is the next in importance. When the mobile phase contains high concentration of salt which can't form complex with the immobilized metal, the hydrophobic interaction between the protein and stationary phase will be increased. As the interaction between the metal chelate ligand and proteins relates to chromatographic operating conditions closely, different elution processes may be selected for different metal chelate columns. The gradient elution is generally performed by the low concentration of salt or different pH for weakly combined columns with proteins, however the competitive elution procedure is commonly utilized for strongly combined column. The experiment showed that NH3 is an excellent competitive eluent. It isn't only give the efficient separation of proteins, but also has the advantages of cheapness, less bleeding of the immobilized metals and ease of controlling NH3

  14. Flue gas desulfurization/denitrification using metal-chelate additives

    Science.gov (United States)

    Harkness, J.B.L.; Doctor, R.D.; Wingender, R.J.

    1985-08-05

    A method of simultaneously removing SO/sub 2/ and NO from oxygen-containing flue gases resulting from the combustion of carbonaceous material by contacting the flue gas with an aqueous scrubber solution containing an aqueous sulfur dioxide sorbent and an active metal chelating agent which promotes a reaction between dissolved SO/sub 2/ and dissolved NO to form hydroxylamine N-sulfonates. The hydroxylamine sulfonates are then separated from the scrubber solution which is recycled. 3 figs.

  15. The attachment of metal-chelating groups to proteins: tagging of albumin by diazonium coupling and use of the products as radiopharmaceuticals

    International Nuclear Information System (INIS)

    Leung, C.S.H.; Meares, C.F.; Goodwin, D.A.

    1978-01-01

    The ability to attach firmly chelated metal ions or powerful chelating agents to sites on biological molecules can enhance the utility of a number of physical techniques now used in the study of biological systems. A 'bifunctional' chelating agent, containing both an EDTA group and a diazonium group, has been prepared and coupled to human serum albumin. The extent of labeling under various conditions and the amino-acid sidechains labeled have been investigated. The reaction of protein-bound chelating groups with added metal ions has been studied, with the finding that only about 40-50% of these groups are available to bind metal ions. Proteolysis of the products leads to recovery of full metal-binding capacity. Properties of the products in vivo are discussed. (author)

  16. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor

    2015-01-22

    The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  17. A bis(3-hydroxy-4-pyridinone)-EDTA derivative as a strong chelator for M3+ hard metal ions: complexation ability and selectivity.

    Science.gov (United States)

    Gama, Sofia; Dron, Paul; Chaves, Silvia; Farkas, Etelka; Santos, M Amélia

    2009-08-21

    The study of chelating compounds is very important to solve problems related to human metal overload. 3-Hydroxy-3-pyridinones (HP), namely deferiprone, have been clinically used for chelating therapy of Fe and Al over the last decade. A multi-disciplinary search for alternative molecules led us to develop poly-(3-hydroxy-4-pyridinones) to increase metal chelation efficacy. We present herein a complexation study of a new bis-(3-hydroxy-4-pyridinone)-EDTA derivative with a set of M(3+) hard metal ions (M = Fe, Al, Ga), as well as Zn(2+), a biologically relevant metal ion. Thus a systematic aqueous solution equilibrium study was performed using potentiometric and spectroscopic techniques (UV-Vis, NMR methods). These set of results enables the establishment of specific models as well as the determination of thermodynamic stability constants and coordination modes of the metal complexes. The results indicate that this ligand has a higher affinity for chelating to these hard metal ions than deferiprone, and that the coordination occurs mostly through the HP moieties. Furthermore, it was also found that this ligand has a higher selectivity for chelating to M(3+) hard metal ions (M = Fe, Al, Ga) than Zn(2+).

  18. Theory of Mind in Adults with HFA and Asperger Syndrome

    Science.gov (United States)

    Spek, Annelies A.; Scholte, Evert M.; Van Berckelaer-Onnes, Ina A.

    2010-01-01

    Theory of mind was assessed in 32 adults with HFA, 29 adults with Asperger syndrome and 32 neurotypical adults. The HFA and Asperger syndrome groups were impaired in performance of the Strange stories test and the Faux-pas test and reported more theory of mind problems than the neurotypical adults. The three groups did not differ in performance of…

  19. Study of chelating agent as a surface modifier for retarding corrosion attack on ferrous metal

    International Nuclear Information System (INIS)

    Nur Ubaidah Saidin; Muhamad Daud; Siti Radiah Mohd Kamarudin; Zaifol Samsu; Azali Muhamad; Rusni Rejab; Mohd Saari Ripin; Mohd Shariff Sattar

    2010-01-01

    A different concentration of chelating agents in electrolyte of 3.5 % NaCl was applied to bare ferrous metal and tested for their effectiveness as a corrosion retardant. The performance of the samples was measured using corrosion measurement system. The results indicated that the contribution of chelating agent was expediting the reduction of the passive film. The anodic behavior was clearly found to be influenced by the concentration of the chelating agent. It was also found that some of the corrosion was apparently converted to protective layer over a period of time. Excessive moisture caused breakdown of film by removing the unreacted chelating agent and causing regrowth of the existing rust. (author)

  20. Heavy Metals, Cardiovascular Disease, and the Unexpected Benefits of Chelation Therapy.

    Science.gov (United States)

    Lamas, Gervasio A; Navas-Acien, Ana; Mark, Daniel B; Lee, Kerry L

    2016-05-24

    This review summarizes evidence from 2 lines of research previously thought to be unrelated: the unexpectedly positive results of TACT (Trial to Assess Chelation Therapy), and a body of epidemiological data showing that accumulation of biologically active metals, such as lead and cadmium, is an important risk factor for cardiovascular disease. Considering these 2 areas of work together may lead to the identification of new, modifiable risk factors for atherosclerotic cardiovascular disease. We examine the history of chelation up through the report of TACT. We then describe work connecting higher metal levels in the body with the future risk of cardiovascular disease. We conclude by presenting a brief overview of a newly planned National Institutes of Health trial, TACT2, in which we will attempt to replicate the findings of TACT and to establish that removal of toxic metal stores from the body is a plausible mechanistic explanation for the benefits of edetate disodium treatment. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  1. Heavy Metals, Cardiovascular Disease, and the Unexpected Benefits of Edetate Disodium Chelation Therapy

    Science.gov (United States)

    Lamas, Gervasio A.; Navas-Acien, Ana; Mark, Daniel B.; Lee, Kerry L.

    2016-01-01

    This review summarizes evidence from 2 lines of research previously thought unrelated: the unexpectedly positive results of the Trial to Assess Chelation Therapy (TACT), and a body of epidemiological data showing that accumulation of biologically active metals, such as lead and cadmium, is an important risk factor for cardiovascular disease. Considering these 2 areas of work together may lead to the identification of new, modifiable risk factors for atherosclerotic cardiovascular disease. We examine the history of chelation up through the report of TACT. We then describe work connecting higher metal levels in the body with the future risk of cardiovascular disease. We conclude by presenting a brief overview of a newly planned National Institutes of Health trial, TACT2, in which we will attempt to replicate the findings of TACT and to establish that removal of toxic metal stores from the body is a plausible mechanistic explanation for the benefits of edetate disodium treatment. PMID:27199065

  2. Protection against SR 4233 (tirapazamine) aerobic cytotoxicity by the metal chelators desferrioxamine and tiron

    International Nuclear Information System (INIS)

    Herscher, L.L.; Krishna, M.C.; Cook, J.A.

    1994-01-01

    Metal chelating agents and antioxidants were evaluated as potential protectors against aerobic SR 4233 cytotoxicity in Chinese hamster V79 cells. The differential protection of aerobic and hypoxic cells by two metal chelators, desferrrioxamine and Tiron, is discussed in the context of their potential use in the on-going clinical trials with SR 4233. Cytotoxicity was evaluated using clonogenic assay. SR 4233 exposure was done in glass flasks as a function of time either alone or in the presence of the following agents: superoxide dismutase, catalase, 5,5-dimethyl-1-pyrroline, Trolox, ICRF-187, desferrioxamine, Tiron (1,2-dihydroxybenzene-3,5-disulfonate), and ascorbic acid. Experiments done under hypoxic conditions were carried out in specially designed glass flasks that were gassed with humidified nitrogen/carbon dioxide mixture and with a side-arm reservoir from which SR 4233 was added to cell media after hypoxia was obtained. Electron paramagnetic resonance studies were also performed. Electron paramagnetic resonance and spectrophotometry experiments suggest that under aerobic conditions SR 4233 undergoes futile redox cycling to produce superoxide. Treatment of cells during aerobic exposure to SR 4233 with the enzymes superoxide dismutase and catalase, the spin trapping agent DMPO, the water-soluble vitamin E analog Trolox, and the metal chelator ICRF-187 provided little or no protection against aerobic SR 4233 cytotoxicity. However, two other metal chelators, desferrioxamine and Tiron afforded significant protection against minimal protection to hypoxic cells treated with SR 4233. One potential mechanism of aerobic cytotoxicity is redox cycling of SR 4233 with molecular oxygen resulting in several potentially toxic oxidative species that overburden the intrinsic intracellular detoxification systems such as superoxide dismutase, catalase, and glutathione peroxidase. 23 refs., 4 figs., 1 tab

  3. Metal-Chelate Immobilization of Lipase onto Polyethylenimine Coated MCM-41 for Apple Flavor Synthesis.

    Science.gov (United States)

    Sadighi, Armin; Motevalizadeh, Seyed Farshad; Hosseini, Morteza; Ramazani, Ali; Gorgannezhad, Lena; Nadri, Hamid; Deiham, Behnaz; Ganjali, Mohammad Reza; Shafiee, Abbas; Faramarzi, Mohammad Ali; Khoobi, Mehdi

    2017-08-01

    An enzyme immobilized on a mesoporous silica nanoparticle can serve as a multiple catalyst for the synthesis of industrially useful chemicals. In this work, MCM-41 nanoparticles were coated with polyethylenimine (MCM-41@PEI) and further modified by chelation of divalent metal ions (M = Co 2+ , Cu 2+ , or Pd 2+ ) to produce metal-chelated silica nanoparticles (MCM-41@PEI-M). Thermomyces lanuginosa lipase (TLL) was immobilized onto MCM-41, MCM-41@PEI, and MCM-41@PEI-M by physical adsorption. Maximum immobilization yield and efficiency of 75 ± 3.5 and 65 ± 2.7% were obtained for MCM@PEI-Co, respectively. The highest biocatalytic activity at extremely acidic and basic pH (pH = 3 and 10) values were achieved for MCM-PEI-Co and MCM-PEI-Cu, respectively. Optimum enzymatic activity was observed for MCM-41@PEI-Co at 75 °C, while immobilized lipase on the Co-chelated support retained 70% of its initial activity after 14 days of storage at room temperature. Due to its efficient catalytic performance, MCM-41@PEI-Co was selected for the synthesis of ethyl valerate in the presence of valeric acid and ethanol. The enzymatic esterification yield for immobilized lipase onto MCM-41@PEI-Co was 60 and 53%, respectively, after 24 h of incubation in n-hexane and dimethyl sulfoxide media. Graphical Abstract Divalent metal chelated polyethylenimine coated MCM-41 (MCM-41@PEI-M) was used for immobilization of Thermomyces lanuginosa lipase catalyzing green apple flavor preparation.

  4. [Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents

    International Nuclear Information System (INIS)

    1991-01-01

    Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III)

  5. [Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-31

    Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

  6. (Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents)

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

  7. Preparation, characterization, magnetic and thermal studies of some chelate polymers of first series transition metal ions

    International Nuclear Information System (INIS)

    Ukey, Vaishali V.; Juneja, H.D.; Borkar, S.D.; Ghubde, R.S.; Naz, S.

    2006-01-01

    Azelaoyl-bis-hydroxamic acid used as bis ligand for the preparation of chelate polymers of Mn(II), Co(II), Ni(II) and Zn(II). These chelate polymers have been synthesized by refluxing the metal acetate and bis ligand as 1:1 stoichiometry. In the present work, structural determination of these newly synthesized chelate polymers has been studied on the basis of elemental analyses, infrared and reflectance spectral, magnetic and thermal studies. The decomposition temperature and the order of reaction have been determined by TGA analysis. On the basis of these studies, the Zn(II) chelate polymer has tetrahedral geometry, whereas Mn(II), Co(II) and Ni(II) chelate polymers have octahedral geometry and have the thermal stability in the order Ni(II) > Mn(II) > Zn(II) > Co(II)

  8. Effects of iron(III)chelates on the solubility of heavy metals in calcareous soils

    Energy Technology Data Exchange (ETDEWEB)

    Ylivainio, Kari, E-mail: kari.ylivainio@mtt.f [Department of Applied Chemistry and Microbiology, FIN-00014 University of Helsinki (Finland)

    2010-10-15

    In this study I evaluated the effects of complexing agents on the solubility of heavy metals in an incubation experiment up to 56 days when complexing agents were applied as Fe-chelates (Fe-EDDS(S,S), Fe-EDDS(mix), Fe-EDTA and Fe-EDDHA) on calcareous soils at a level sufficient to correct Fe chlorosis (0.1 mmol kg{sup -1}). Of these ligands, EDDHA was the most efficient in keeping Fe in water-soluble form, and EDDS increased the solubility of Cu and Zn most, and only EDTA increased the solubility of Cd and Pb. EDTA increased the solubility of Ni steadily during the incubation period, equalling about 5-8% of the added EDTA concentration. [S,S]-EDDS was biodegraded within 56 days, whereas EDDS(mix) was less biodegradable. Ni-chelates were the most recalcitrant against biodegradation. The study shows that even a moderate input of chelates to soil increases the solubility of toxic heavy metals and their risk of leaching. - When correcting Fe chlorosis Fe-EDDS causes lower environmental concern than Fe-EDTA.

  9. Effects of iron(III)chelates on the solubility of heavy metals in calcareous soils

    International Nuclear Information System (INIS)

    Ylivainio, Kari

    2010-01-01

    In this study I evaluated the effects of complexing agents on the solubility of heavy metals in an incubation experiment up to 56 days when complexing agents were applied as Fe-chelates (Fe-EDDS(S,S), Fe-EDDS(mix), Fe-EDTA and Fe-EDDHA) on calcareous soils at a level sufficient to correct Fe chlorosis (0.1 mmol kg -1 ). Of these ligands, EDDHA was the most efficient in keeping Fe in water-soluble form, and EDDS increased the solubility of Cu and Zn most, and only EDTA increased the solubility of Cd and Pb. EDTA increased the solubility of Ni steadily during the incubation period, equalling about 5-8% of the added EDTA concentration. [S,S]-EDDS was biodegraded within 56 days, whereas EDDS(mix) was less biodegradable. Ni-chelates were the most recalcitrant against biodegradation. The study shows that even a moderate input of chelates to soil increases the solubility of toxic heavy metals and their risk of leaching. - When correcting Fe chlorosis Fe-EDDS causes lower environmental concern than Fe-EDTA.

  10. Effects of iron(III)chelates on the solubility of heavy metals in calcareous soils.

    Science.gov (United States)

    Ylivainio, Kari

    2010-10-01

    In this study I evaluated the effects of complexing agents on the solubility of heavy metals in an incubation experiment up to 56 days when complexing agents were applied as Fe-chelates (Fe-EDDS(S,S), Fe-EDDS(mix), Fe-EDTA and Fe-EDDHA) on calcareous soils at a level sufficient to correct Fe chlorosis (0.1 mmol kg(-1)). Of these ligands, EDDHA was the most efficient in keeping Fe in water-soluble form, and EDDS increased the solubility of Cu and Zn most, and only EDTA increased the solubility of Cd and Pb. EDTA increased the solubility of Ni steadily during the incubation period, equalling about 5-8% of the added EDTA concentration. [S,S]-EDDS was biodegraded within 56 days, whereas EDDS(mix) was less biodegradable. Ni-chelates were the most recalcitrant against biodegradation. The study shows that even a moderate input of chelates to soil increases the solubility of toxic heavy metals and their risk of leaching. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  11. 24 CFR 266.510 - HFA responsibilities.

    Science.gov (United States)

    2010-04-01

    ... HOUSING FINANCE AGENCY RISK-SHARING PROGRAM FOR INSURED AFFORDABLE MULTIFAMILY PROJECT LOANS Project... accordance with the physical inspection procedures in 24 CFR part 5, subpart G. (b) Annual audits of projects. The HFA must analyze projects' annual audits and provide a copy to HUD along with a summary of...

  12. Effects of nutrient trace metal speciation on algal growth in the presence of the chelator [S,S]-EDDS

    NARCIS (Netherlands)

    Schowanek, D.; McAvoy, D.; Versteeg, D.; Hanstveit, A.

    1996-01-01

    This study tests the hypothesis that the apparent toxicity of strong chelators in standard algal growth inhibition tests (e.g. method OECD 201, EC C.3., ISO 8692) is related to essential trace metal bioavailability. This hypothesis was investigated for the chelator [S,S]-ethylene diamine disuccinate

  13. Various types of metal complexes based on chelating {beta}-diketones and their structural analogues

    Energy Technology Data Exchange (ETDEWEB)

    Skopenko, Viktor V; Amirkhanov, Vladimir M; Sliva, T Yu [Department of Chemistry, Kyiv National Taras Shevchenko University (Ukraine); Vasilchenko, Igor S; Anpilova, E L; Garnovskii, Alexander D [Institute of Physical and Organic Chemistry, Rostov State University, Rostov-on-Don (Russian Federation)

    2004-08-31

    Data on the synthesis and structures of {beta}-diketonates and their N,P-containing structural analogues are generalised and described systematically. The possibility of creating diverse metal complexes with various modes of coordination of typical chelating ligands is discussed.

  14. Various types of metal complexes based on chelating β-diketones and their structural analogues

    International Nuclear Information System (INIS)

    Skopenko, Viktor V; Amirkhanov, Vladimir M; Sliva, T Yu; Vasilchenko, Igor S; Anpilova, E L; Garnovskii, Alexander D

    2004-01-01

    Data on the synthesis and structures of β-diketonates and their N,P-containing structural analogues are generalised and described systematically. The possibility of creating diverse metal complexes with various modes of coordination of typical chelating ligands is discussed.

  15. [Enhanced Phytoextraction of Heavy Metals from Contaminated Soils Using Sedum alfredii Hance with Biodegradable Chelate GLDA].

    Science.gov (United States)

    Wei, Ze-bin; Chen, Xiao-hong; Wu, Qi-tang; Tan, Meng

    2015-05-01

    Chemically enhanced phytoextraction by hyperaccumulator has been proposed as an effective approach to remove heavy metals from contaminated soil. Pot experiment was conducted to investigate the effect of application of the biodegradable chelate GLDA (L glutamic acid N,N-diacetic acid) at different doses or the combination of GLDA with EDTA (ethylenediamine tetraacetic acid) or CIT (citric acid) on the uptake of Cd, Zn and Pb by Sedum alfredii Hance (a Zn and Cd hyperaccumulator). Experimental results showed that GLDA addition to soil significantly increased the concentrations of Cd and Zn in Sedum alfredii Hance and its Cd and Zn phytoextraction compared to the control. Additionally, GLDA at 2.5 mmol · kg(-1) resulted in the highest phytoextraction, being 2.5 and 2.6 folds of the control for Cd and Zn, respectively. However, the combined application of GLDA + EDTA (1:1) and GLDA + CIT (1 :1 and 1:3) at a total dose of 5 mmol · kg(-1) did not increase the phytoextraction of Zn and Cd, compared to the GLDA only treatment. Therefore, the biodegradable chelate GLDA could be regarded as a good chelate candidate for the phytoextraction of heavy metals of heavy metals from contaminated soils, particularly for Cd and Zn contaminated soils.

  16. Fluid extraction using carbon dioxide and organophosphorus chelating agents

    Science.gov (United States)

    Smart, Neil G.; Wai, Chien M.; Lin, Yuehe; Kwang, Yak Hwa

    1998-01-01

    Methods for extracting metalloid and metal species from a solid or liquid material by exposing the material to a fluid solvent, particularly supercritical CO.sub.2, and a chelating agent are described. The chelating agent forms a chelate with the species, the chelate being soluble in the fluid to allow removal of the species from the material. In preferred embodiments the extraction solvent is supercritical CO.sub.2 and the chelating agent comprises an organophosphorous chelating agent, particularly sulfur-containing organophosphorous chelating agents, including mixtures of chelating agents. Examples of chelating agents include monothiophosphinic acid, di-thiophosphinic acid, phosphine sulfite, phosphorothioic acid, and mixtures thereof. The method provides an environmentally benign process for removing metal and metalloids from industrial waste solutions, particularly acidic solutions. Both the chelate and the supercritical fluid can be regenerated and the contaminant species recovered to provide an economic, efficient process.

  17. Transition Metal Chelator Induces Progesterone Production in Mouse Cumulus-Oocyte Complexes and Corpora Lutea.

    Science.gov (United States)

    Tian, X; Anthony, K; Diaz, Francisco J

    2017-04-01

    Progesterone production is upregulated in granulosa cells (cumulus and mural) after the LH surge, but the intra-follicular mechanisms regulating this transition are not completely known. Recent findings show that the transition metal chelator, N,N,N',N'-tetrakis-(2-pyridylmethyl)-ethylenediamine (TPEN), impairs ovarian function. In this study, we provide evidence that chelating transition metals, including zinc, enhances progesterone production. The findings show that TPEN (transition metal chelator) increases abundance of Cyp11a1 and Star messenger RNA (mRNA) between 8- and 20-fold and progesterone production more than 3-fold in cultured cumulus-oocyte complexes (COC). Feeding a zinc-deficient diet for 10 days, but not 3 days, increased Star, Hsd3b, and prostaglandin F2 alpha receptor (Ptgfr) mRNA ~2.5-fold, suggesting that the effect of TPEN is through modulation of zinc availability. Progesterone from cumulus cells promotes oocyte developmental potential. Blocking progesterone production with epostane during maturation reduced subsequent blastocyst formation from 89 % in control to 18 % in epostane-treated complexes, but supplementation with progesterone restored blastocyst developmental potential to 94 %. Feeding a zinc-deficient diet for 5 days before ovulation did not affect the number of CL, STAR protein, or serum progesterone. However, incubating luteal tissue with TPEN increased abundance of Star, Hsd3b, and Ptgfr mRNA 2-3-fold and increased progesterone production 3-fold. TPEN is known to abolish SMAD2/3 signaling in cumulus cells. However, treatment of COC with the SMAD2/3 phosphorylation inhibitor, SB421542, did not by itself induce steroidogenic transcripts but did potentiate EGF-induced Star mRNA expression. Collectively, the results show that depletion of transition metals with TPEN acutely enhances progesterone biosynthesis in COC and luteal tissue.

  18. Synthesis, characterization and ion- exchange study of poly[(2,4-dihydroxy benzophenone)butylene] resin and its poly chelates with transition metals

    International Nuclear Information System (INIS)

    Joshi, J. D.; Patel, N.B.; Patel, S. D.

    2006-01-01

    The polymeric ligand poly[(2,4-dihydroxy benzophenone)butylene] H(DHBP-BD) forms 1 :2 metal-ligand complexes with Ni(ll), Co(ll), Cu(ll) and Zn(ll). The polymeric ligand and its poly chelates were characterized on the basis of elemental analyses, magnetic susceptibilities, IR-spectroscopy, UV-visible spectra, NMR, thermogravimetric analyses. The molecular weight of resin was determined using number average molecular weight (M n ) by vapour pressure osmometry method. The stereochemistry in case of the Cu(ll) poly chelate is square-planar, tetrahedral for Zn(ll) and octahedral for Ni(ll) and Co(ll). The stereochemistry in each chelate is proposed on the basis of magnetic susceptibilities and electronic spectra. The IR spectra show that the bidentate ligand coordinates through the oxygen atom of the carbonyl and phenolic group with replacement of hydrogen by metal ions, respectively. All the chelates are paramagnetic in nature except the Zn(ll) chelate which is diamagnetic. The ion-exchange study of the prepared resin was checked by batch equilibration method with selected metal ions [Cu(ll), Ni(ll), Fe(lll) and UO 2 2+( VI)] at varying electrolyte concentration, pH and time. It is found that, resin can be used as an ion-exchanger

  19. Solid-state chelation of metal ions by ethylenediaminetetraacetate intercalated in a layered double hydroxide.

    Science.gov (United States)

    Tarasov, Konstantin A; O'Hare, Dermot; Isupov, Vitaly P

    2003-03-24

    The solid-state chelation of transition metal ions (Co(2+), Ni(2+), and Cu(2+)) from aqueous solutions into the lithium aluminum layered double hydroxide ([LiAl(2)(OH)(6)]Cl x 0.5H(2)O or LDH) which has been pre-intercalated with EDTA (ethylenediaminetetraacetate) ligand has been investigated. The intercalated metal cations form [M(edta)](2)(-) complexes between the LDH layers as indicated by elemental analysis, powder X-ray diffraction, and IR and UV-vis spectroscopies. If metal chloride or nitrate salts are used in the reaction with the LDH then co-intercalation of either the Cl(-) or NO(3)(-) anions is observed. In the case of metal acetate salts the cations intercalate without the accompanying anion. This can be explained by the different intercalation selectivity of the anions in relation to the LDH. In the latter case the introduction of the positive charge into LDH structure was compensated for by the release from the solid of the equivalent quantity of lithium and hydrogen cations. Time-resolved in-situ X-ray diffraction measurements have revealed that the chelation/intercalation reactions proceed very quickly. The rate of the reaction found for nickel acetate depends on concentration as approximately k[Ni(Ac)(2)](3).

  20. Spectroscopy, modeling and computation of metal chelate solubility in supercritical CO2. Annual progress report, September 15, 1996 - September 14, 1997

    International Nuclear Information System (INIS)

    Brennecke, J.F.; Chateauneuf, J.E.; Stadtherr, M.A.

    1997-01-01

    'This progress report contains (1) a statement of the objectives of the overall project, (2) a discussion of the results obtained during the first year of the three year grant period, (3) a summary, (4) a description of the future work that will be pursued during the next year, and (5) accounting information. This is followed by the literature cited and the pertinent tables and figures. The overall objectives of this project are to gain a fundamental understanding of the solubility and stability of metal chelates in supercritical CO 2 . Extraction with CO 2 is a excellent way to remove organic compounds from soils, sludges and aqueous solutions and recent research has demonstrated that together with chelating agents it is a viable way to remove metals, as well. The authors seek to gain fundamental knowledge that is vital to computing phase behavior, and modeling and designing processes using CO 2 to separate organics and metal compounds from DOE mixed wastes. The overall program is a comprehensive one to measure local solvation of metal chelates and to determine metal chelate stability in supercritical fluid mixtures using UV-vis and FTIR spectroscopy. The spectroscopic studies provide information on the solution microstructure, which they are using in concert with their own and published solubility data to evaluate and develop thermodynamic models of the solubility behavior. Finally, they are implementing a more reliable computational technique, based on interval mathematics, to compute the phase equilibria using the thermodynamic models. This fundamental information about metal chelate stability and solubility in supercritical CO 2 is important in the design of processes using CO 2 to extract components from mixed wastes and in determining the optimum operating conditions.'

  1. Quantum Chemical Investigation on the Antioxidant Activity of Neutral and Anionic Forms of Juglone: Metal Chelation and Its Effect on Radical Scavenging Activity

    Directory of Open Access Journals (Sweden)

    Aymard Didier Fouegue Tamafo

    2017-01-01

    Full Text Available The chelation ability of divalent Mg, Ca, Fe, Co, Ni, Cu, Zn, and monovalent Cu ions by neutral and anionic forms of juglone has been investigated at DFT/B3LYP/6-31+G(d,p level of theory in gas and aqueous phases. It is noteworthy that only the 1 : 1 stoichiometry was considered herein. The effects of these metals on the radical scavenging activity of neutral juglone were evaluated via the usual descriptors of hydrogen atom transfer. According to our results, metal chelation by the two forms of juglone was spontaneous and exothermic in both media. Based on the binding energies, Cu(II ion showed the highest affinity for the ligands. QTAIM analyses identified the metal-ligand bonds as intermediate type interactions in all the chelates, except those of Ca and Mg. It was also found that the chelates were better radical scavengers than the ligands. In the gas phase, the scavenging activity of the compounds was found to be governed by direct hydrogen atom transfer, the Co(II chelate being the most reactive. In the aqueous phase also, the sequential proton loss electron transfer was preferred by all the molecules, while the Cu(II chelates were the most reactive.

  2. Use of non-hyperaccumulator plant species for the phytoextraction of heavy metals using chelating agents

    Directory of Open Access Journals (Sweden)

    Lucas Anjos Souza

    2013-08-01

    Full Text Available Soil contamination by heavy metals is a challenge faced by many countries, and engineering technologies to solve this problem are expensive and can cause negative impacts on the environment. One way to minimise the levels of heavy metals in the soil is to use plants that can absorb and accumulate heavy metals into harvestable parts, a process called phytoextraction. Typical plant species used in research involving phytoextraction are heavy metal hyperaccumulators, but plants from this group are not good biomass producers and grow more slowly than most species; thus, they have an important role in helping scientists understand the mechanisms involved in accumulating high amounts of heavy metals without developing symptoms or dying. However, because of their slow growth, it is not practical to use these species for phytoextraction. An alternative approach is to use non-hyperaccumulator plants assisted by chelating agents, which may improve the ability of plants to accumulate more heavy metals than they would naturally. Chelating agents can be synthetic or organic acids, and the advantages and disadvantages of their use in improving the phytoextraction potential of non-hyperaccumulator plants are discussed in this article. We hope to draw attention to ways to improve the phytoextraction potential of non-hyperaccumulator plants that produce a large amount of biomass and to stimulate more research on phytoextraction-inducing substances.

  3. 8-Hydroxyquinolines: a review of their metal chelating properties and medicinal applications

    Directory of Open Access Journals (Sweden)

    Prachayasittikul V

    2013-10-01

    Full Text Available Veda Prachayasittikul,1 Supaluk Prachayasittikul,2 Somsak Ruchirawat,3 Virapong Prachayasittikul11Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, 2Center of Data Mining and Biomedical Informatics, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand; 3Laboratory of Medicinal Chemistry, Chulabhorn Research Institute and Chulabhorn Graduate Institute, Bangkok, ThailandAbstract: Metal ions play an important role in biological processes and in metal homeostasis. Metal imbalance is the leading cause for many neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis. 8-Hydroxyquinoline (8HQ is a small planar molecule with a lipophilic effect and a metal chelating ability. As a result, 8HQ and its derivatives hold medicinal properties such as antineurodegenerative, anticancer, antioxidant, antimicrobial, anti-inflammatory, and antidiabetic activities. Herein, diverse bioactivities of 8HQ and newly synthesized 8HQ-based compounds are discussed together with their mechanisms of actions and structure–activity relationships.Keywords: metal binding compound, antineurodegenerative, anticancer, antidiabetic, multifunctional actions, structure–activity relationships

  4. Immobilization of heavy metals on pillared montmorillonite with a grafted chelate ligand.

    Science.gov (United States)

    Brown, Loren; Seaton, Kenneth; Mohseni, Ray; Vasiliev, Aleksey

    2013-10-15

    The objective of this work was the development of an efficient adsorbent for irreversible immobilization of heavy metals in contaminated soils. The adsorbent was prepared by pillaring of montmorillonite with silica followed by grafting of a chelate ligand on its surface. Obtained adsorbent was mesoporous with high content of adsorption sites. Its structure was studied by BET adsorption of N2, dynamic light scattering, and scanning electron microscopy. The adsorption capacity of the organoclay was measured by its mixing with contaminated kaolin and soil samples and by analysis of heavy metal contents in leachate. Deionized water and 50% acetic acid were used for leaching of metals from the samples. As it was demonstrated by the experiments, the adsorbent was efficient in immobilization of heavy metals not only in neutral aqueous media but also in the presence of weak acid. As a result, the adsorbent can be used for reduction of heavy metal leaching from contaminated sites. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. ChelomEx: Isotope-assisted discovery of metal chelates in complex media using high-resolution LC-MS.

    Science.gov (United States)

    Baars, Oliver; Morel, François M M; Perlman, David H

    2014-11-18

    Chelating agents can control the speciation and reactivity of trace metals in biological, environmental, and laboratory-derived media. A large number of trace metals (including Fe, Cu, Zn, Hg, and others) show characteristic isotopic fingerprints that can be exploited for the discovery of known and unknown organic metal complexes and related chelating ligands in very complex sample matrices using high-resolution liquid chromatography mass spectrometry (LC-MS). However, there is currently no free open-source software available for this purpose. We present a novel software tool, ChelomEx, which identifies isotope pattern-matched chromatographic features associated with metal complexes along with free ligands and other related adducts in high-resolution LC-MS data. High sensitivity and exclusion of false positives are achieved by evaluation of the chromatographic coherence of the isotope pattern within chromatographic features, which we demonstrate through the analysis of bacterial culture media. A built-in graphical user interface and compound library aid in identification and efficient evaluation of results. ChelomEx is implemented in MatLab. The source code, binaries for MS Windows and MAC OS X as well as test LC-MS data are available for download at SourceForge ( http://sourceforge.net/projects/chelomex ).

  6. Iminodiacetic acid functionalised organopolymer monoliths: application to the separation of metal cations by capillary high-performance chelation ion chromatography.

    Science.gov (United States)

    Moyna, Áine; Connolly, Damian; Nesterenko, Ekaterina; Nesterenko, Pavel N; Paull, Brett

    2013-03-01

    Lauryl methacrylate-co-ethylene dimethacrylate monoliths were polymerised within fused silica capillaries and subsequently photo-grafted with varying amounts of glycidyl methacrylate (GMA). The grafted monoliths were then further modified with iminodiacetic acid (IDA), resulting in a range of chelating ion-exchange monoliths of increasing capacity. The IDA functional groups were attached via ring opening of the epoxy group on the poly(GMA) structure. Increasing the amount of attached poly(GMA), via photo-grafting with increasing concentrations of GMA, from 15 to 35%, resulted in a proportional and controlled increase in the complexation capacity of the chelating monoliths. Scanning capacitively coupled contactless conductivity detection (sC(4)D) was used to characterise and verify homogenous distribution of the chelating ligand along the length of the capillaries non-invasively. Chelation ion chromatographic separations of selected transition and heavy metals were carried out, with retention factor data proportional to the concentration of grafted poly(GMA). Average peak efficiencies of close to 5,000 N/m were achieved, with the isocratic separation of Na, Mg(II), Mn(II), Co(II), Cd(II) and Zn(II) possible on a 250-mm-long monolith. Multiple monolithic columns produced to the same recipes gave RSD data for retention factors of ions). The monolithic chelating ion-exchanger was applied to the separation of alkaline earth and transition metal ions spiked in natural and potable waters.

  7. Effects of a chelating resin on metal bioavailability and toxicity to estuarine invertebrates: Divergent results of field and laboratory tests

    International Nuclear Information System (INIS)

    Wilkie, Emma M.; Roach, Anthony C.; Micevska, Tina; Kelaher, Brendan P.; Bishop, Melanie J.

    2010-01-01

    Benthic invertebrates can uptake metals through diffusion of free ion solutes, or ingestion of sediment-bound forms. This study investigated the efficacy of the metal chelating resin SIR 300 TM in adsorbing porewater metals and isolating pathways of metal exposure. A field experiment (Botany Bay, Sydney, Australia) and a laboratory toxicity test each manipulated the availability of porewater metals within contaminated and uncontaminated sediments. It was predicted that within contaminated sediments, the resin would adsorb porewater metals and reduce toxicity to invertebrates, but in uncontaminated sediments, the resin would not significantly affect these variables. Whereas in the laboratory, the resin produced the predicted results, in the field the resin increased porewater metal concentrations of contaminated sediments for at least 34 days and decreased abundances of four macroinvertebrate groups, and richness in all sediments. These contrasting findings highlight the limits of extrapolating the results of laboratory experiments to the field environment. - Laboratory experiments do not predict the effects on porewater metals or macroinvertebrates of adding a chelating resin to metal-contaminated field sediments.

  8. Effects of a chelating resin on metal bioavailability and toxicity to estuarine invertebrates: Divergent results of field and laboratory tests

    Energy Technology Data Exchange (ETDEWEB)

    Wilkie, Emma M., E-mail: ewilkie@bio.mq.edu.a [Department of Environmental Sciences, University of Technology Sydney, Broadway, NSW 2007 (Australia); Ecotoxicology and Environmental Contaminants Section, Department of Environment and Climate Change, Lidcombe, NSW 1825 (Australia); Roach, Anthony C. [Ecotoxicology and Environmental Contaminants Section, Department of Environment and Climate Change, Lidcombe, NSW 1825 (Australia); Micevska, Tina [Centre for Environmental Contaminants Research, CSIRO Land and Water, Menai, NSW 2234 (Australia); Kelaher, Brendan P.; Bishop, Melanie J. [Department of Environmental Sciences, University of Technology Sydney, Broadway, NSW 2007 (Australia)

    2010-05-15

    Benthic invertebrates can uptake metals through diffusion of free ion solutes, or ingestion of sediment-bound forms. This study investigated the efficacy of the metal chelating resin SIR 300{sup TM} in adsorbing porewater metals and isolating pathways of metal exposure. A field experiment (Botany Bay, Sydney, Australia) and a laboratory toxicity test each manipulated the availability of porewater metals within contaminated and uncontaminated sediments. It was predicted that within contaminated sediments, the resin would adsorb porewater metals and reduce toxicity to invertebrates, but in uncontaminated sediments, the resin would not significantly affect these variables. Whereas in the laboratory, the resin produced the predicted results, in the field the resin increased porewater metal concentrations of contaminated sediments for at least 34 days and decreased abundances of four macroinvertebrate groups, and richness in all sediments. These contrasting findings highlight the limits of extrapolating the results of laboratory experiments to the field environment. - Laboratory experiments do not predict the effects on porewater metals or macroinvertebrates of adding a chelating resin to metal-contaminated field sediments.

  9. Synthesis and thermal characterization of new ternary chelates of piroxicam and tenoxicam with glycine and DL-phenylalanine and some transition metals

    Science.gov (United States)

    Zayed, M. A.; El-Dien, F. A. Nour; Mohamed, Gehad G.; El-Gamel, Nadia E. A.

    2006-05-01

    The ternary chelates of piroxicam (Pir) and tenoxicam (Ten) with Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) in the presence of various amino acids such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized with different physicochemical methods. IR spectra confirm that Pir and Ten behave as a neutral bidentate ligand coordinated to the metal ions via the pyridine- N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its deprotonated carboxylic group. In addition, PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its deprotonated carboxylic and amino groups. The solid reflectance spectra and magnetic moment measurements confirm that all the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. Thermal behaviour of the complexes is extensively studied using TG and DTA techniques. TG results show that water molecules (hydrated and coordinated) and anions are removed in the first and second steps while Gly, PhA, Pir and Ten are decomposed in the next and subsequent steps. The pyrolyses of the chelates into different gases are observed in the DTA curves as exo- or endothermic peaks. Also, phase transition states are observed in some chelates. Different thermodynamic parameters are calculated using Coats-Redfern method and the results are interpreted.

  10. Potentials and drawbacks of chelate-enhanced phytoremediation of soils

    NARCIS (Netherlands)

    Römkens, P.F.A.M.; Bouwman, L.A.; Japenga, J.; Draaisma, C.

    2002-01-01

    Chelate-enhanced phytoremediation has been proposed as an effective tool for the extraction of heavy metals from soils by plants. However, side-effects related to the addition of chelates, e.g. metal leaching and effects on soil micro-organisms, were usually neglected. Therefore, greenhouse and

  11. Extracting metals directly from metal oxides

    International Nuclear Information System (INIS)

    Wai, C.M.; Smart, N.G.; Phelps, C.

    1997-01-01

    A method of extracting metals directly from metal oxides by exposing the oxide to a supercritical fluid solvent containing a chelating agent is described. Preferably, the metal is an actinide or a lanthanide. More preferably, the metal is uranium, thorium or plutonium. The chelating agent forms chelates that are soluble in the supercritical fluid, thereby allowing direct removal of the metal from the metal oxide. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of β-diketones, halogenated β-diketones, phosphinic acids, halogenated phosphinic acids, carboxylic acids, halogenated carboxylic acids, and mixtures thereof. In especially preferred embodiments, at least one of the chelating agents is fluorinated. The method provides an environmentally benign process for removing metals from metal oxides without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the metal recovered, to provide an economic, efficient process. 4 figs

  12. Chelation in metal intoxication. V. Lowering of manganese content in poisoned rat organs

    Energy Technology Data Exchange (ETDEWEB)

    Tandon, S K; Mathur, A K

    1976-01-01

    Metal chelation has been considered useful in the management of manganese poisoning to a considerable extent. Our own studies in this direction have shown that some polyaminocarboxylic acids and a few amino acids are effective in not only removing manganese from the vital organs of experimentally poisoned animals but also in restoring certain metal induced biochemical and histological changes in such organs. Further, the success of p-aminosalicylic acid (PAS), a chemotherapeutic agent for tuberculosis, in manganese mobilization has led us to examine some other structurally related compounds together with a few other possible metal binding agents for their ability to remove excess metal from the organs, their sub-cellular fractions and blood cells of manganese administered rats and to investigate if there exists any relationship between the structure of such compounds and their metal mobilizing capacity. The present communication deals with the results of these investigations.

  13. Preparation, Spectroscopic Investigation and Biological Activity of New Mixed Ligand Chelates

    International Nuclear Information System (INIS)

    Alassbaly, F.S.; Ajaily, M.M.E.

    2014-01-01

    Preparation and investigation of new Co(II), Ni(II), Zn(II) and Cr(III) chelates with mixed ligands including Schiff base (L1) formed from the condensation of 4-dimethylaminobenzaldehyde with 2-aminophenol and anthranilic acid (L2) were studied. The obtained Schiff base and mixed ligand chelates were subjected to several physiochemical techniques, in terms of CHN elemental analyses, molar conductivity, magnetic moment measurements, infrared, proton nuclear magnetic resonance, electronic and mass spectra. The analytical data showed the formation of the Schiff base compound and the ratio of metal to ligands of the chelates are 1:1:1(M:L1:L2). The infrared spectral data exhibited that the used ligands behaving as bidentate ligands towards the metal ions. The proton nuclear magnetic resonance spectral data showed the signals of the active groups in the ligands which entered in chelation with Zn(II) metal ion. The electronic spectral results showed the existence of pie (phenyl ring) and n = pie (C=N) of the ligands and suggested the geometrical structures of the chelates. Meanwhile, the mass spectral data revealed the fragmentations of the Schiff base, anthranilic acid and their Ni(II) mixed ligand chelate has been preformed the only chelate conducted for justification. All the prepared mixed chelates were non-electrolyte in nature. The antibacterial activity of the Schiff base, anthranilic acid, metal salts and mixed ligand chelates were studied and found to be that mixed ligand chelates have the most biological activity in comparison to the free ligands and salts. (author)

  14. Comparison of synthetic chelators and low molecular weight organic acids in enhancing phytoextraction of heavy metals by two ecotypes of Sedum alfredii Hance.

    Science.gov (United States)

    Liu, Dan; Islam, Ejazul; Li, Tingqiang; Yang, Xiaoe; Jin, Xiaofen; Mahmood, Qaisar

    2008-05-01

    Lab scale and pot experiments were conducted to compare the effects of synthetic chelators and low molecular weight organic acids (LMWOA) on the phytoextraction of multi-contaminated soils by two ecotypes of Sedum alfredii Hance. Through lab scale experiments, the treatment dosage of 5 and 10 mM for synthetic chelators and LMWOA, respectively, and the treatment time of 10 days were selected for pot experiment. In pot experiment, the hyperaccumulating ecotype (HE) was found more tolerant to the metal toxicity compared with the non-hyperaccumulating ecotype (NHE). EDTA for Pb, EDDS for Cu, and DTPA for Cu and Cd were found more effective to enhance heavy metal accumulation in the shoots of S. alfredii Hance. Compared with synthetic chelators, the phytoextraction ability of LMWOA was lesser. Considering the strong post-harvest effects of synthetic chelators, it is suggested that higher dosage of LMWOA could be practiced during phytoextraction, and some additional measures could also be taken to lower the potential environmental risks of synthetic chelators in the future studies.

  15. Synthesis and characterisation of 8-hydroxyquinoline-bovine serum albumin conjugates as metal ion chelating proteins

    International Nuclear Information System (INIS)

    Giraudi, G.; Baggiani, C.; Giovannoli, C.; Marletto, C.; Vanni, A.

    1999-01-01

    A derivative of 8-hydroxyquinoline (8-quinolinol, oxine) with a linking bridge containing a carboxylic group was covalently coupled to bovine serum albumin by the N-hydroxysuccinimide method to obtain stable monomeric conjugates with oxine to protein mole ratios up to 37. These conjugates were characterised spectrophotometrically and their complexation properties were confirmed by spectral analysis with and without the addition of Al(III), Cd(II), Co(II), Cu(II), Hg(II), Mn(II), Ni(II), Pb(II), V(IV), U(VI) and Zn(II) ions added. The maximum number of ions bound by these chelating proteins was determined spectrophotometrically by titration with metal ions at pH 6.0. The conjugates with a substitution ratio (moles of 8-hydroxyquinoline bound/mole of albumin) less than about 8 showed 1:1 binding with metal ions, while conjugates with higher substitution ratios were able to complex with 2:1 ratio of 8-hydroxyquinoline to metal ion. Association and dissociation kinetics of complexation with copper(II) ions showed a complex mechanism. The spectral and binding properties of these metal ion-binding proteins confirm that the coupling of the 8-hydroxyquinoline derivative to bovine serum albumin gives stable, water soluble, macromolecular chelating agents that retain the complexing ability of the original ligand. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  16. Chelation therapy to prevent diabetes-associated cardiovascular events.

    Science.gov (United States)

    Diaz, Denisse; Fonseca, Vivian; Aude, Yamil W; Lamas, Gervasio A

    2018-05-24

    For over 60 years, chelation therapy with disodium ethylene diamine tetraacetic acid (EDTA, edetate) had been used for the treatment of cardiovascular disease (CVD) despite lack of scientific evidence for efficacy and safety. The Trial to Assess Chelation Therapy (TACT) was developed and received funding from the National Institutes of Health (NIH) to ascertain the safety and efficacy of chelation therapy in patients with CVD. This pivotal trial demonstrated an improvement in outcomes in postmyocardial infarction (MI) patients. Interestingly, it also showed a particularly large reduction in CVD events and all-cause mortality in the prespecified subgroup of patients with diabetes. The TACT results may support the concept of metal chelation to reduce metal-catalyzed oxidation reactions that promote the formation of advanced glycation end products, a precursor of diabetic atherosclerosis. In this review, we summarize the epidemiological and basic evidence linking toxic metal accumulation and diabetes-related CVD, supported by the salutary effects of chelation in TACT. If the ongoing NIH-funded TACT2, in diabetic post-MI patients, proves positive, this unique therapy will enter the armamentarium of endocrinologists and cardiologists seeking to reduce the atherosclerotic risk of their diabetic patients.

  17. Synthesis of Poly(hydroxamic Acid-Poly(amidoxime Chelating Ligands for Removal of Metals from Industrial Wastewater

    Directory of Open Access Journals (Sweden)

    M. R. Lutfor

    2011-01-01

    Full Text Available Synthesis of poly(hydroxamic acid-poly(amidoxime chelating ligands were carried out from poly(methyl acrylate-co-acrylonitrile grafted sago starch and hydroxylamine in alkaline medium. The binding property of metal ions was performed and maximum sorption capacity of the copper was 3.20 mmol/ g and the rate of exchange of some metals was faster, i.e. t½ ≈ 7 min (average. Two types of wastewater containing chromium, zinc, nickel, copper and iron, etc. were used and the heavy metal recovery was found to be highly efficient, about 99% of the metals could be removed from the metal plating wastewater.

  18. Phytoextraction of heavy metals from contaminated soil by co-cropping with chelator application and assessment of associated leaching risk.

    Science.gov (United States)

    Wei, Z B; Guo, X F; Wu, Q T; Long, X X; Penn, C J

    2011-08-01

    Phytoextraction using hyperaccumulating plants is generally time-consuming and requires the cessation of agriculture. We coupled chelators and a co-cropping system to enhance phytoextraction rates, while allowing for agricultural production. An experiment on I m3 lysimeter beds was conducted with a co-cropping system consisting of the hyperaccumulator Sedum alfredii and low-accumulating corn (Zea Mays, cv. Huidan-4), with addition ofa mixture of chelators (MC), to assess the efficiency of chelator enhanced co-crop phytoextraction and the leaching risk caused by the chelator. The results showed that the addition of MC promoted the growth of S. alfredii in the first crop (spring-summer season) and significantly increased the metal phytoextraction. The DTPA-extractable and total metal concentrations in the topsoil were also reduced more significantly with the addition of MC compared with the control treatments. However, mono-cropped S. alfredii without MC was more suitable for maximizing S. alfredii growth and therefore phytoextraction of Zn and Cd during the autumn-winter seasons. No adverse impact to groundwater due to MC application was observed during the experiments with three crops and three MC applications. But elevated total Cd and Pb concentrations among subsoils compared to the initial subsoil concentrations were found for the co-crop + MC treatment after the third crop.

  19. Spectral, biological screening of metal chelates of chalcone based Schiff bases of N-(3-aminopropyl) imidazole.

    Science.gov (United States)

    Kalanithi, M; Rajarajan, M; Tharmaraj, P; Sheela, C D

    2012-02-15

    Tridentate chelate complexes of Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the chalcone based ligands 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-(phenylallyl)]phenol(HL(1)), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-p-tolylallyl]phenol(HL(2)), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-4-nitrophenylallyl]phenol(HL(3)). Microanalytical data, UV-vis spectrophotometric method, magnetic susceptibility measurements, IR, 1H NMR, Mass, and EPR techniques were used to characterize the structure of chelates. The electronic absorption spectra and magnetic susceptibility measurements suggest a distorted square planar geometry for the copper(II) ion. The other metal complexes show distorted tetrahedral geometry. The coordination of the ligands with metal(II) ions was further confirmed by solution fluorescence spectrum. The antimicrobial activity of the ligands and metal(II) complexes against the species Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albigans and Aspergillus niger has been carried out and compared. The electrochemical behavior of copper(II) complex is studied by cyclic voltammetry. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Immobilization of heavy metals on pillared montmorillonite with a grafted chelate ligand

    International Nuclear Information System (INIS)

    Brown, Loren; Seaton, Kenneth; Mohseni, Ray; Vasiliev, Aleksey

    2013-01-01

    Highlights: • Mesoporous organoclay for immobilization of heavy metal cations was obtained. • The material has a porous structure with high contents of surface adsorption sites. • Leaching of heavy metals from soil reduced in the presence of this adsorbent. • The adsorbent demonstrated high effectiveness in neutral and acidic media. -- Abstract: The objective of this work was the development of an efficient adsorbent for irreversible immobilization of heavy metals in contaminated soils. The adsorbent was prepared by pillaring of montmorillonite with silica followed by grafting of a chelate ligand on its surface. Obtained adsorbent was mesoporous with high content of adsorption sites. Its structure was studied by BET adsorption of N 2 , dynamic light scattering, and scanning electron microscopy. The adsorption capacity of the organoclay was measured by its mixing with contaminated kaolin and soil samples and by analysis of heavy metal contents in leachate. Deionized water and 50% acetic acid were used for leaching of metals from the samples. As it was demonstrated by the experiments, the adsorbent was efficient in immobilization of heavy metals not only in neutral aqueous media but also in the presence of weak acid. As a result, the adsorbent can be used for reduction of heavy metal leaching from contaminated sites

  1. Adsorption characteristics of 14C-labeled alanine, aspartic acid and adenosine triphosphate by metal-chelating resins

    International Nuclear Information System (INIS)

    Ishiyama, Toshio; Matsunami, Tadao; Shibata, Setsuko; Honda, Yoshihide.

    1987-01-01

    (1) Adsorption properties of 14 C-alanine, 14 C-ATP (adenosine triphosphate) and 14 C-aspartic acid on the metal-chelating resins were determined and found that the Cu(II)-Chelex 100 and Fe(III)-Unicellex UR10, Fe(III)-Chelex 100 chelating resins were highly effective for the adsorption of 14 C-alanine and 14 C-ATP, respectively. (2) Desorption rate of 14 C-ATP from the Fe(III)-Unicellex UR10 and Fe(III)-Chelex 100 resins was somewhat higher than the case of 14 C-alanine, probably because the coordination bonds of Cu-alanine might be stronger than those of Fe-ATP. Thus, 14 C-labeled organic compounds such as 14 C-alanine and 14 C-ATP of a low activity concentration (3.7 mBq/ml) (1 x 10 -7 μCi/ml) in aqueous solution may be measured with liquid scintillation counter after pre-concentration by use of the Fe(III)- and Cu(II)-chelating resin columns. (author)

  2. New biodegradable organic-soluble chelating agents for simultaneous removal of heavy metals and organic pollutants from contaminated media

    International Nuclear Information System (INIS)

    Ullmann, Amos; Brauner, Neima; Vazana, Shlomi; Katz, Zhanna; Goikhman, Roman; Seemann, Boaz; Marom, Hanit; Gozin, Michael

    2013-01-01

    Highlights: • New soil remediation process using phase transition of partially miscible solvents. • Design and synthesis of new bio-degradable, organic soluble chelating agents. • Feasibility tests of the process on authentically polluted sediments and sludge. • Simultaneous removal of toxic metals and organic pollutants was demonstrated. -- Abstract: Advanced biodegradable and non-toxic organic chelators, which are soluble in organic media, were synthesized on the basis of the S,S-ethylenediamine-disuccinate (S,S-EDDS) ligand. The modifications suggested in this work include attachment of a lipophilic hydrocarbon chain (“tail”) to one or both nitrogen atoms of the S,S-EDDS. The new ligands were designed and evaluated for application in the Sediments Remediation Phase Transition Extraction (SR-PTE) process. This novel process is being developed for the simultaneous removal of both heavy metals and organic pollutants from contaminated soils, sediments or sludge. The new chelators were designed to bind various target metal ions, to promote extraction of these ions into organic solvents. Several variations of attached tails were synthesized and tested. The results for one of them, N,N′-bis-dodecyl-S,S-EDDS (C24-EDDS), showed that the metal-ligand complexes are concentrated in the organic-rich phase in the Phase Transition Extraction process (more than 80%). Preliminary applications of the SR-PTE process with the C24-EDDS ligand were conducted also on actually contaminated sludge (field samples). The extraction of five toxic metals, namely, Cd, Cu, Ni, Pb and Zn was examined. In general, the extraction performance of the new ligand was not less than that of S,S-EDDS when a sufficient ligand-to-extracted ion ratio (about 4:1 was applied

  3. New biodegradable organic-soluble chelating agents for simultaneous removal of heavy metals and organic pollutants from contaminated media

    Energy Technology Data Exchange (ETDEWEB)

    Ullmann, Amos, E-mail: Ullmann@eng.tau.ac.il [Faculty of Engineering, School of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Brauner, Neima; Vazana, Shlomi; Katz, Zhanna [Faculty of Engineering, School of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Goikhman, Roman [The Hebrew University of Jerusalem, The Robert H. Smith, Faculty of Agriculture, Food and Environment, Rehovot (Israel); Seemann, Boaz; Marom, Hanit [School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Gozin, Michael, E-mail: cogozin@gmail.com [School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

    2013-09-15

    Highlights: • New soil remediation process using phase transition of partially miscible solvents. • Design and synthesis of new bio-degradable, organic soluble chelating agents. • Feasibility tests of the process on authentically polluted sediments and sludge. • Simultaneous removal of toxic metals and organic pollutants was demonstrated. -- Abstract: Advanced biodegradable and non-toxic organic chelators, which are soluble in organic media, were synthesized on the basis of the S,S-ethylenediamine-disuccinate (S,S-EDDS) ligand. The modifications suggested in this work include attachment of a lipophilic hydrocarbon chain (“tail”) to one or both nitrogen atoms of the S,S-EDDS. The new ligands were designed and evaluated for application in the Sediments Remediation Phase Transition Extraction (SR-PTE) process. This novel process is being developed for the simultaneous removal of both heavy metals and organic pollutants from contaminated soils, sediments or sludge. The new chelators were designed to bind various target metal ions, to promote extraction of these ions into organic solvents. Several variations of attached tails were synthesized and tested. The results for one of them, N,N′-bis-dodecyl-S,S-EDDS (C24-EDDS), showed that the metal-ligand complexes are concentrated in the organic-rich phase in the Phase Transition Extraction process (more than 80%). Preliminary applications of the SR-PTE process with the C24-EDDS ligand were conducted also on actually contaminated sludge (field samples). The extraction of five toxic metals, namely, Cd, Cu, Ni, Pb and Zn was examined. In general, the extraction performance of the new ligand was not less than that of S,S-EDDS when a sufficient ligand-to-extracted ion ratio (about 4:1 was applied.

  4. Synthesis, Characterization and Antimicrobial Activity of Metal Chelates of 5-[4-Chloro phenyl(1, 3, 4thiadiazol-2-ylamino methylene]-8-hydroxy quinoline

    Directory of Open Access Journals (Sweden)

    Divyesh K. Patel

    2009-01-01

    Full Text Available 5-Chloromethyl-8-quinolinol was condensed stoichiometrically with 5-(4-chlorophenyl-(1,3,4 thiadiazol-2-ylamine in the presence of sodium bicarbonate. The resulting 5-[4-chlorophenyl-(1,3,4thiadiazol-2-ylamino methylene]-8-quinolinol (CTAQ was characterized by elemental analysis and spectral studies. The transition metal chelates viz. Cu2+, Ni2+, Co2+, Mn2+ and Zn2+ of CTAQ were prepared and characterized by metal-ligand (M:L ratio, IR and reflectance spectroscopies and magnetic properties. The antifungal activity of CTAQ and its metal chelates was screened against various fungi. The results show that all these samples are good antifungal agents.

  5. 24 CFR 266.100 - Qualified housing finance agency (HFA).

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Qualified housing finance agency (HFA). 266.100 Section 266.100 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR HOUSING-FEDERAL HOUSING COMMISSIONER, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT MORTGAGE...

  6. [Continuous remediation of heavy metal contaminated soil by co-cropping system enhanced with chelator].

    Science.gov (United States)

    Wei, Ze-Bin; Guo, Xiao-Fang; Wu, Qi-Tang; Long, Xin-Xian

    2014-11-01

    In order to elucidate the continuous effectiveness of co-cropping system coupling with chelator enhancement in remediating heavy metal contaminated soils and its environmental risk towards underground water, soil lysimeter (0.9 m x 0.9 m x 0.9 m) experiments were conducted using a paddy soil affected by Pb and Zn mining in Lechang district of Guangdong Province, 7 successive crops were conducted for about 2.5 years. The treatments included mono-crop of Sedum alfredii Hance (Zn and Cd hyperaccumulator), mono-crop of corn (Zea mays, cv. Yunshi-5, a low-accumulating cultivar), co-crop of S. alfredii and corn, and co-crop + MC (Mixture of Chelators, comprised of citric acid, monosodium glutamate waste liquid, EDTA and KCI with molar ratio of 10: 1:2:3 at the concentration of 5 mmol x kg(-1) soil). The changes of heavy metal concentrations in plants, soil and underground water were monitored. Results showed that the co-cropping system was suitable only in spring-summer seasons and significantly increased Zn and Cd phytoextraction. In autumn-winter seasons, the growth of S. alfredii and its phytoextraction of Zn and Cd were reduced by co-cropping and MC application. In total, the mono-crops of S. alfredii recorded a highest phytoextraction of Zn and Cd. However, the greatest reduction of soil Zn, Cd and Pb was observed with the co-crop + MC treatment, the reduction rates were 28%, 50%, and 22%, respectively, relative to the initial soil metal content. The reduction of this treatment was mainly attributed to the downwards leaching of metals to the subsoil caused by MC application. The continuous monitoring of leachates during 2. 5 year's experiment also revealed that the addition of MC increased heavy metal concentrations in the leaching water, but they did not significantly exceed the III grade limits of the underground water standard of China.

  7. Chelation therapy after the Trial to Assess Chelation Therapy: results of a unique trial

    Science.gov (United States)

    Avila, Maria D.; Escolar, Esteban; Lamas, Gervasio A.

    2014-01-01

    Purpose of review EDTA chelation therapy has been in off-label use for the treatment of atherosclerosis. We review the results of the first large-scale randomized trial of this treatment. Recent findings The trial to assess chelation therapy was a $30 million National Institutes of Health-funded study of the safety and efficacy of EDTA-based chelation infusions in 1708 post-myocardial infarction (MI) patients. The trial to assess chelation therapy demonstrated a significant (P = 0.035) 18% reduction in a combined primary endpoint of death, MI, stroke, coronary revascularization, or hospitalization for angina. In diabetic patients the benefit was more extreme, with a 41% relative reduction in risk (P = 0.0002) and a 43% reduction in total mortality (P = 0.011). Safety data were favorable. A reduction of oxidative stress by chelation of toxic metals has been proposed as a possible mechanism of action. Summary Recent research suggests that EDTA chelation may be a well-tolerated and effective treatment for post-MI patients. Future replication and mechanistic studies are important prior to implementation in all post-MI patients. PMID:25023079

  8. Chelating extractants of improved selectivity. Progress report, September 1, 1976--October 31, 1977

    International Nuclear Information System (INIS)

    Freiser, H.

    1977-07-01

    New means of characterizing metal chelating reagent selectivity have been developed and incorporated into a theoretical factor analysis of the chelate stability constants of 24 metal ions with 14 ligands of the EDTA family. The factor analysis will be extended to extracting ligand families. A computer-controlled automated metal chelate stability constant apparatus has been assembled and successfully tested. A high performance liquid chromatograph has been set up and preliminary examination of comparison of reversed phase chromatographic separation of metal ions with their solvent extraction behavior begun

  9. Article choice in children with High Functioning Autism (HFA) and in children with Specific Language Impairment (SLI).

    NARCIS (Netherlands)

    Schaeffer, J.; van Witteloostuijn, M.; de Haan, D.

    2014-01-01

    This study reports on the choice between a definite and an indefinite article by children with High Functioning Autism (HFA) and children with Specific Language Impairment (SLI). We carried out an elicited production task with 16 Dutch-speaking non-grammatically impaired children with HFA aged 6-13,

  10. Chelating agents in pharmacology, toxicology and therapeutics

    International Nuclear Information System (INIS)

    1988-01-01

    The proceedings contain 71 abstracts of papers. Fourteen abstracts were inputted in INIS. The topics covered include: the effects of chelating agents on the retention of 63 Ni, 109 Cd, 203 Hg, 144 Ce, 95 Nb and the excretion of 210 Po, 63 Ni, 48 V, 239 Pu, 241 Am, 54 Mn; the applications of tracer techniques for studies of the efficacy of chelation therapy in patients with heart and brain disorders; and the treatment of metal poisoning with chelating agents. (J.P.)

  11. The use of chelating agents in the remediation of metal-contaminated soils: A review

    Energy Technology Data Exchange (ETDEWEB)

    Lestan, Domen [Agronomy Department, Centre for Soil and Environmental Science, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana (Slovenia); Luo Chunling [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Li Xiangdong [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)], E-mail: cexdli@polyu.edu.hk

    2008-05-15

    This paper reviews current remediation technologies that use chelating agents for the mobilization and removal of potentially toxic metals from contaminated soils. These processes can be done in situ as enhanced phytoextraction, chelant enhanced electrokinetic extraction and soil flushing, or ex situ as the extraction of soil slurry and soil heap/column leaching. Current proposals on how to treat and recycle waste washing solutions after soil is washed are discussed. The major controlling factors in phytoextraction and possible strategies for reducing the leaching of metals associated with the application of chelants are also reviewed. Finally, the possible impact of abiotic and biotic soil factors on the toxicity of metals left after the washing of soil and enhanced phytoextraction are briefly addressed. - The use of synthetic chelants for soil washing and enhanced phytoextraction by plants has been well studied for the remediation of metal-contaminated soils in the last two decades.

  12. The use of chelating agents in the remediation of metal-contaminated soils: A review

    International Nuclear Information System (INIS)

    Lestan, Domen; Luo Chunling; Li Xiangdong

    2008-01-01

    This paper reviews current remediation technologies that use chelating agents for the mobilization and removal of potentially toxic metals from contaminated soils. These processes can be done in situ as enhanced phytoextraction, chelant enhanced electrokinetic extraction and soil flushing, or ex situ as the extraction of soil slurry and soil heap/column leaching. Current proposals on how to treat and recycle waste washing solutions after soil is washed are discussed. The major controlling factors in phytoextraction and possible strategies for reducing the leaching of metals associated with the application of chelants are also reviewed. Finally, the possible impact of abiotic and biotic soil factors on the toxicity of metals left after the washing of soil and enhanced phytoextraction are briefly addressed. - The use of synthetic chelants for soil washing and enhanced phytoextraction by plants has been well studied for the remediation of metal-contaminated soils in the last two decades

  13. Effects of chemical modifications on photophysics and exciton dynamics on {pi}-conjugation attenuated and metal-chelated photoconducting polymers

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L. X.; Jager, W. J. H.; Gosztola, D. J.; Niemczyk, M. P.; Wasielewski, M. R.

    2000-03-11

    Effects of two types of chemical modifications on photoconducting polymers consisting of polyphenylenevinylene (PPV) derivatives are studied by static and ultrafast transient optical spectroscopy as well as semi-empirical ZINDO calculations. The first type of modification inserts 2,2{prime}-bipyridyl-5-vinylene units (bpy V) in the PPV backbone, and the second type involves metal-chelation with the bpy sites. Photoluminescence and exciton dynamics of polymers 1 and 2 with PV:bpyV ratios of 1 and 3 were examined in solution, and compared to those of the homopolymer, poly(2,5-bis(2{prime}-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV). Similar studies were carried out for several metal-chelated polymers. These results can be explained by changes in {pi}-conjugation throughout the polymer backbone. The attenuation in {pi}-conjugation by the chemical modifications transforms a conducting polymer from one-dimensional semiconductor to molecular aggregates.

  14. Chromatographic methods for determination of metals as chelate compounds with heterocyclic azo reagents

    International Nuclear Information System (INIS)

    Basova, E.M.; Bol'shova, T.A.; Shpigun, O.A.; Ivanov, V.M.

    1993-01-01

    Methods for separation and concentration of transition metals as well as cadmium in form of chelates with heterocyclic azo compounds namely, PAN(1-(2-pyridylaso)-2-naphthol), PAR(4-(2-pyridylazo)-resorcin), Br-PAAP (2-(5-bromine-2-pyridylazo)-5-diethyl aminophenol) are considered. The Br-PAAP reagent is the most sensitive and widely-applied one in extraction and highly-efficient liquid chromatography. Methods of sorption concentration with subsequent element determination directly on the sorbent without microelements separation or destruction are the most promissing ones

  15. Synthesis, spectroscopic studies and antimicrobial activity of chelates 2-(acetyloxy)-benzoic acid with transition metals (CR+3, MN+2, NI+2 AND CU+2)

    International Nuclear Information System (INIS)

    Khan, B.; Mateen, B.; Ahmed, F.; Ahmed, F.

    2007-01-01

    2-(acetyloxy)-Benzoic acid chelates with Cr+3, Mn+2, Ni+2 and Cu+2 were synthesized and characterized by the melting point, solubility, Fourier Transform Infrared (FT-IR) Spectroscopy, Atomic Absorption Spectroscopy (AAS), X-Ray Diffraction (XRD) method and evaluated by antimicrobial activity. The functional group present in the chelates was determined by Fourier Transform Infrared Spectroscopy, by X-Ray Diffraction analysis crystal data of chelates, their inter-atomic and inter-planer spacing was also determined. The amount of metal in the chelates was estimated by Atomic Absorption Spectroscopy and their Antimicrobial Activity was studied against Pseudomonas aeruginosa, Escherisha coli and Staphylococcus aureus. (author)

  16. Structure-Activity Relationships and Identification of Optmized CC-Chemokine Receptor CCR1, 5, and 8 Metal-Ion Chelators

    DEFF Research Database (Denmark)

    Chalikiopoulos, Alexander; Thiele, Stefanie; Malmgaard-Clausen, Mikkel

    2013-01-01

    Chemokine receptors are involved in trafficking of leukocytes and represent targets for autoimmune conditions, inflammatory diseases, viral infections, and cancer. We recently published CCR1, CCR8, and CCR5 agonists and positive modulators based on a three metal-ion chelator series: 2,2'-bipyridi...

  17. Synthesis and characterization of dihexyldithiocarbamate as a chelating agent in extraction of gold(III)

    Energy Technology Data Exchange (ETDEWEB)

    Fatimah, Soja Siti, E-mail: soja-sf@upi.edu [Departemen Pendidikan Kimia, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudhi No. 229, Bandung 40154 (Indonesia); Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang, Km. 21, Jatinangor (Indonesia); Bahti, Husein H.; Hastiawan, Iwan [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang, Km. 21, Jatinangor (Indonesia); Permanasari, Anna [Departemen Pendidikan Kimia, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudhi No. 229, Bandung 40154 (Indonesia)

    2016-02-08

    The use of dialkyldithiocarbamates as chelating agents of transition metals have been developing for decades. Many chelating agents have been synthesized and used in the extraction of the metals. Studies on particular aspects of extraction of the metals, such as the effect of increasing hydrophobicity of chelating agents on the effectiveness of the extraction, have been done. However, despite the many studies on the synthesis and applications of this type of chelating agents, interests in the aspect of molecular structure of the synthesized ligands and of their complexes, have been limited. This study aimed at synthesizing and characterizing dihexylthiocarbamate, and using the ligand for the extraction of gold III). Characterization of the ligand and of its metal complex were done by using elemental analysis, DTG, and spectroscopic methods to include NMR, ({sup 1}H, and {sup 13}C), FTIR, and MS-ESI. Data on the synthesis, characterization, and the application of the ligand as a chelating agent are presented.

  18. Synthesis and characterization of dihexyldithiocarbamate as a chelating agent in extraction of gold(III)

    Science.gov (United States)

    Fatimah, Soja Siti; Bahti, Husein H.; Hastiawan, Iwan; Permanasari, Anna

    2016-02-01

    The use of dialkyldithiocarbamates as chelating agents of transition metals have been developing for decades. Many chelating agents have been synthesized and used in the extraction of the metals. Studies on particular aspects of extraction of the metals, such as the effect of increasing hydrophobicity of chelating agents on the effectiveness of the extraction, have been done. However, despite the many studies on the synthesis and applications of this type of chelating agents, interests in the aspect of molecular structure of the synthesized ligands and of their complexes, have been limited. This study aimed at synthesizing and characterizing dihexylthiocarbamate, and using the ligand for the extraction of gold III). Characterization of the ligand and of its metal complex were done by using elemental analysis, DTG, and spectroscopic methods to include NMR, (1H, and 13C), FTIR, and MS-ESI. Data on the synthesis, characterization, and the application of the ligand as a chelating agent are presented.

  19. Metal chelators and neurotoxicity: lead, mercury, and arsenic.

    Science.gov (United States)

    Bjørklund, Geir; Mutter, Joachim; Aaseth, Jan

    2017-12-01

    This article reviews the clinical use of the metal chelators sodium 2,3-dimercapto-1-propanesulfonate (DMPS), meso-2,3-dimercaptosuccinic acid (DMSA), and calcium disodium edetate (CaEDTA, calcium EDTA) in overexposure and poisonings with salts of lead (Pb), mercury (Hg), and arsenic (As). DMSA has considerably lower toxicity than the classic heavy metal antagonist BAL (2,3-dimercaptopropanol) and is also less toxic than DMPS. Because of its adverse effects, CaEDTA should be replaced by DMSA as the antidote of choice in treating moderate Pb poisoning. Combination therapy with BAL and CaEDTA was previously recommended in cases of severe acute Pb poisoning with encephalopathy. We suggest that BAL in such cases acted as a shuttling Pb transporter from the intra- to the extracellular space. The present paper discusses if a combination of the extracellularly distributed DMSA with the ionophore, Monensin may provide a less toxic combination for Pb mobilization by increasing both the efflux of intracellularly deposited Pb and the urinary Pb excretion. Anyhow, oral therapy with DMSA should be continued with several intermittent courses. DMPS and DMSA are also promising antidotes in Hg poisoning, whereas DMPS seems to be a more efficient agent against As poisoning. However, new insight indicates that a combination of low-dosed BAL plus DMPS could be a preferred antidotal therapy to obtain mobilization of the intracerebral deposits into the circulation for subsequent rapid urinary excretion.

  20. Leaching variations of heavy metals in chelator-assisted phytoextraction by Zea mays L. exposed to acid rainfall.

    Science.gov (United States)

    Lu, Yayin; Luo, Dinggui; Liu, Lirong; Tan, Zicong; Lai, An; Liu, Guowei; Li, Junhui; Long, Jianyou; Huang, Xuexia; Chen, Yongheng

    2017-11-01

    Chelant-enhanced phytoextraction method has been put forward as an effective soil remediation method, whereas the heavy metal leaching could not be ignored. In this study, a cropping-leaching experiment, using soil columns, was applied to study the metal leaching variations during assisted phytoextraction of Cd- and Pb-polluted soils, using seedlings of Zea mays, applying three different chelators (EDTA, EDDS, and rhamnolipid), and artificial rainfall (acid rainfall or normal rainfall). It showed that artificial rainfall, especially artificial acid rain, after chelator application led to the increase of heavy metals in the leaching solution. EDTA increased both Cd and Pb concentrations in the leaching solution, obviously, whereas EDDS and rhamnolipid increased Cd concentration but not Pb. The amount of Cd and Pb decreased as the leaching solution increased, the patterns as well matched LRMs (linear regression models), with R-square (R 2 ) higher than 90 and 82% for Cd and Pb, respectively. The maximum cumulative Cd and Pb in the leaching solutions were 18.44 and 16.68%, respectively, which was amended by EDTA and acid rainwater (pH 4.5), and followed by EDDS (pH 4.5), EDDS (pH 6.5), rhamnolipid (0.5 g kg -1 soil, pH 4.5), and rhamnolipid (pH 6.5).

  1. Chelating agents as stationary phase in extraction chromatography, ch. 11

    International Nuclear Information System (INIS)

    Sebesta, F.

    1975-01-01

    Chelating agents have been used largely in extraction chromatography for separations related to activation analysis, for concentration of metals from dilute solutions, and for preparation of radiochemically pure or carrier-free radionuclides. This review deals with the theory of extraction by chelating agents, the experimental technique, and the chelating agents and systems used (β-diketones, oximes, hydroxamic acid, dithizone and diethyldithiocarbamic acid)

  2. Chelation technology: a promising green approach for resource management and waste minimization.

    Science.gov (United States)

    Chauhan, Garima; Pant, K K; Nigam, K D P

    2015-01-01

    Green chemical engineering recognises the concept of developing innovative environmentally benign technologies to protect human health and ecosystems. In order to explore this concept for minimizing industrial waste and for reducing the environmental impact of hazardous chemicals, new greener approaches need to be adopted for the extraction of heavy metals from industrial waste. In this review, a range of conventional processes and new green approaches employed for metal extraction are discussed in brief. Chelation technology, a modern research trend, has shown its potential to develop sustainable technology for metal extraction from various metal-contaminated sites. However, the interaction mechanism of ligands with metals and the ecotoxicological risk associated with the increased bioavailability of heavy metals due to the formation of metal-chelant complexes is still not sufficiently explicated in the literature. Therefore, a need was felt to provide a comprehensive state-of-the-art review of all aspects associated with chelation technology to promote this process as a green chemical engineering approach. This article elucidates the mechanism and thermodynamics associated with metal-ligand complexation in order to have a better understanding of the metal extraction process. The effects of various process parameters on the formation and stability of complexes have been elaborately discussed with respect to optimizing the chelation efficiency. The non-biodegradable attribute of ligands is another important aspect which is currently of concern. Therefore, biotechnological approaches and computational tools have been assessed in this review to illustrate the possibility of ligand degradation, which will help the readers to look for new environmentally safe mobilizing agents. In addition, emerging trends and opportunities in the field of chelation technology have been summarized and the diverse applicability of chelation technology in metal extraction from

  3. Effect of keratin on heavy metal chelation and toxicity to aquatic organisms

    Energy Technology Data Exchange (ETDEWEB)

    Coello, W.F.; Khan, M.A.Q. [Univ. of Illinois, Chicago, IL (United States). Dept. of Biological Sciences

    1998-12-31

    The presence of fresh scales and human hair in water can reduce the toxicity of lead nitrate at and above 6 ppb to fish. This ability is lost on drying and storage, but can be restored if dried hair or scales are treated with a solution of amino acids. The chelation ability of keratin in amino acid-treated scales or hair is retained for months on dry storage. Addition of these hair and/or scales to solutions of lead nitrate, mercuric chloride and a mixture of both, and cupric sulfate reduced the toxicity of these solutions to Daphnia magna and Dreissena polymorpha (zebra mussels). Toxicity of 10 ppm solutions of salts of 27 different metals to daphnids was similarly reduced after filtration through scales or hair. A mixture of a 2 ppb concentration of each of these 27 metals also became nonlethal to daphnids in the presence of, or filtration through, treated scales or hair. 0.25 g of treated hair or scale can be used indefinitely, again and again, to remove the mixture of these 27 metals from their fresh solution in 1 L water if the keratin is frequently rinsed with 0.1% nitric acid to remove the bound metals. The keratin in scales, this, may be the most important ectodermal secretion in absorbing metals from polluted environments and in providing protection against their toxic levels.

  4. Bifunctional chelating agent for the design and development of site specific radiopharmaceuticals and biomolecule conjugation strategy

    Science.gov (United States)

    Katti, Kattesh V.; Prabhu, Kandikere R.; Gali, Hariprasad; Pillarsetty, Nagavara Kishore; Volkert, Wynn A.

    2003-10-21

    There is provided a method of labeling a biomolecule with a transition metal or radiometal in a site specific manner to produce a diagnostic or therapeutic pharmaceutical compound by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radio metal or a transition metal, and covalently linking the resulting metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. Also provided is a method of synthesizing the --PR.sub.2 containing biomolecules by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radiometal or a transition metal, and covalently linking the resulting radio metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. There is provided a therapeutic or diagnostic agent comprising a --PR.sub.2 containing biomolecule.

  5. Mixed ligand chelates of rare earths in aqueous solution

    International Nuclear Information System (INIS)

    Lakhani, S.U.; Thakur, G.S.; Sangal, S.P.

    1981-01-01

    Mixed ligand chelates of the 1:1 trivalent lanthanoids-EDTA, HEDTA and NTA chelates-1, 2-Dihydroxybenzene (Pyrocatechol) have been investigated at 35degC and 0.2 M ionic strength maintained by NaC10 4 . The formation of mixed ligand chelates has been found in all cases. The formation of mixed ligand chelates with EDTA shows the coordination number of lanthanoids to be eight, while the mixed ligand chelates with HEDTA and NTA shows the coordination number to be seven and six respectively. The stability constants of mixed ligand chelates are smaller than the binary complexes. The order of stability constants with respect to primary ligands follows the order NTA>HEDTA>EDTA. With respect to metal ions the stability constants increases with the decrease in ionic radii such as Gd< Er< Yb. (author)

  6. Glyphosate, a chelating agent-relevant for ecological risk assessment?

    Science.gov (United States)

    Mertens, Martha; Höss, Sebastian; Neumann, Günter; Afzal, Joshua; Reichenbecher, Wolfram

    2018-02-01

    Glyphosate-based herbicides (GBHs), consisting of glyphosate and formulants, are the most frequently applied herbicides worldwide. The declared active ingredient glyphosate does not only inhibit the EPSPS but is also a chelating agent that binds macro- and micronutrients, essential for many plant processes and pathogen resistance. GBH treatment may thus impede uptake and availability of macro- and micronutrients in plants. The present study investigated whether this characteristic of glyphosate could contribute to adverse effects of GBH application in the environment and to human health. According to the results, it has not been fully elucidated whether the chelating activity of glyphosate contributes to the toxic effects on plants and potentially on plant-microorganism interactions, e.g., nitrogen fixation of leguminous plants. It is also still open whether the chelating property of glyphosate is involved in the toxic effects on organisms other than plants, described in many papers. By changing the availability of essential as well as toxic metals that are bound to soil particles, the herbicide might also impact soil life, although the occurrence of natural chelators with considerably higher chelating potentials makes an additional impact of glyphosate for most metals less likely. Further research should elucidate the role of glyphosate (and GBH) as a chelator, in particular, as this is a non-specific property potentially affecting many organisms and processes. In the process of reevaluation of glyphosate its chelating activity has hardly been discussed.

  7. Selective Removal of Toxic Metals like Copper and Arsenic from Drinking Water Using Phenol-Formaldehyde Type Chelating Resins

    Directory of Open Access Journals (Sweden)

    Debasis Mohanty

    2009-01-01

    Full Text Available The concentration of different toxic metals has increased beyond environmentally and ecologically permissible levels due to the increase in industrial activity. More than 100 million people of Bangladesh and West Bengal in India are affected by drinking ground water contaminated with arsenic and some parts of India is also affected by poisoning effect of copper, cadmium and fluoride. Different methods have been evolved to reduce the arsenic concentration in drinking water to a maximum permissible level of 10 μg/L where as various methods are also available to separate copper from drinking water. Of the proven methods available today, removal of arsenic by polymeric ion exchangers has been most effective. While chelating ion exchange resins having specific chelating groups attached to a polymer have found extensive use in sorption and pre concentration of Cu2+ ions. Both the methods are coupled here to separate and preconcentrate toxic metal cation Cu2+ and metal anion arsenate(AsO4– at the same time. We have prepared a series of low-cost polymeric resins, which are very efficient in removing copper ion from drinking water and after coordinating with copper ion they act as polymeric ligand exchanger, which are efficiently removing arsenate from drinking water. For this purpose Schiff bases were prepared by condensing o-phenylenediamine with o-, m-, and p-hydroxybenzaldehydes. Condensing these phenolic Schiff bases with formaldehyde afforded the chelating resins in high yields. These resins are loaded with Cu2+, Ni2+ 2+, and Fe3+ ions. The resins and the polychelates are highly insoluble in water. In powdered form the metal ion-loaded resins are found to very efficiently remove arsenate ion from water at neutral pH. Resins loaded with optimum amount of Cu2+ ion is more effective in removing arsenate ions compared to those with Fe3+ ion, apparently because Cu2+ is a stronger Lewis acid than Fe3+. Various parameters influencing the removal of the

  8. Factors affecting the shear bond strength of metal and ceramic brackets bonded to different ceramic surfaces.

    Science.gov (United States)

    Abu Alhaija, Elham S J; Abu AlReesh, Issam A; AlWahadni, Ahed M S

    2010-06-01

    The aims of this study were to evaluate the shear bond strength (SBS) of metal and ceramic brackets bonded to two different all-ceramic crowns, IPS Empress 2 and In-Ceram Alumina, to compare the SBS between hydrofluoric acid (HFA), phosphoric acid etched, and sandblasted, non-etched all-ceramic surfaces. Ninety-six all-ceramic crowns were fabricated resembling a maxillary left first premolar. The crowns were divided into eight groups: (1) metal brackets bonded to sandblasted 9.6 per cent HFA-etched IPS Empress 2 crowns; (2) metal brackets bonded to sandblasted 9.6 per cent HFA-etched In-Ceram crowns; (3) ceramic brackets bonded to sandblasted 9.6 per cent HFA-etched IPS Empress 2 crowns; (4) ceramic brackets bonded to sandblasted 9.6 per cent HFA-etched In-Ceram crowns; (5) metal brackets bonded to sandblasted 37 per cent phosphoric acid-etched IPS Empress 2 crowns; (6) metal brackets bonded to sandblasted 37 per cent phosphoric acid-etched In-Ceram crowns; (7) metal brackets bonded to sandblasted, non-etched IPS Empress 2 crowns; and (8) metal brackets bonded to sandblasted, non-etched In-Ceram crowns. Metal and ceramic orthodontic brackets were bonded using a conventional light polymerizing adhesive resin. An Instron universal testing machine was used to determine the SBS at a crosshead speed of 0.1 mm/minute. Comparison between groups was performed using a univariate general linear model and chi-squared tests. The highest mean SBS was found in group 3 (120.15 +/- 45.05 N) and the lowest in group 8 (57.86 +/- 26.20 N). Of all the variables studied, surface treatment was the only factor that significantly affected SBS (P Empress 2 and In-Ceram groups.

  9. Regeneration of Three-Way Automobile Catalysts using Biodegradable Metal Chelating Agent – S, S-Ethylenediamine Disuccinic Acid (S, S-EDDS)

    Science.gov (United States)

    Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S. Ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel environmentally friendly solvent in removing various c...

  10. A general chelate-assisted co-assembly to metallic nanoparticles-incorporated ordered mesoporous carbon catalysts for Fischer-Tropsch synthesis.

    Science.gov (United States)

    Sun, Zhenkun; Sun, Bo; Qiao, Minghua; Wei, Jing; Yue, Qin; Wang, Chun; Deng, Yonghui; Kaliaguine, Serge; Zhao, Dongyuan

    2012-10-24

    The organization of different nano objects with tunable sizes, morphologies, and functions into integrated nanostructures is critical to the development of novel nanosystems that display high performances in sensing, catalysis, and so on. Herein, using acetylacetone as a chelating agent, phenolic resol as a carbon source, metal nitrates as metal sources, and amphiphilic copolymers as a template, we demonstrate a chelate-assisted multicomponent coassembly method to synthesize ordered mesoporous carbon with uniform metal-containing nanoparticles. The obtained nanocomposites have a 2-D hexagonally arranged pore structure, uniform pore size (~4.0 nm), high surface area (~500 m(2)/g), moderate pore volume (~0.30 cm(3)/g), uniform and highly dispersed Fe(2)O(3) nanoparticles, and constant Fe(2)O(3) contents around 10 wt %. By adjusting acetylacetone amount, the size of Fe(2)O(3) nanoparticles is readily tunable from 8.3 to 22.1 nm. More importantly, it is found that the metal-containing nanoparticles are partially embedded in the carbon framework with the remaining part exposed in the mesopore channels. This unique semiexposure structure not only provides an excellent confinement effect and exposed surface for catalysis but also helps to tightly trap the nanoparticles and prevent aggregating during catalysis. Fischer-Tropsch synthesis results show that as the size of iron nanoparticles decreases, the mesoporous Fe-carbon nanocomposites exhibit significantly improved catalytic performances with C(5+) selectivity up to 68%, much better than any reported promoter-free Fe-based catalysts due to the unique semiexposure morphology of metal-containing nanoparticles confined in the mesoporous carbon matrix.

  11. Investigation of DOTA-Metal Chelation Effects on the Chemical Shift of 129 Xe

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, K; Slack, CC; Vassiliou, CC; Dao, P; Gomes, MD; Kennedy, DJ; Truxal, AE; Sperling, LJ; Francis, MB; Wemmer, DE; Pines, A

    2015-09-17

    Recent work has shown that xenon chemical shifts in cryptophane-cage sensors are affected when tethered chelators bind to metals. Here in this paper, we explore the xenon shifts in response to a wide range of metal ions binding to diastereomeric forms of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) linked to cryptophane-A. The shifts induced by the binding of Ca2+, Cu2+, Ce3+, Zn2+, Cd2+, Ni2+, Co2+, Cr2+, Fe3+, and Hg2+ are distinct. In addition, the different responses of the diastereomers for the same metal ion indicate that shifts are affected by partial folding with a correlation between the expected coordination number of the metal in the DOTA complex and the chemical shift of 129Xe. Lastly, these sensors may be used to detect and quantify many important metal ions, and a better understanding of the basis for the induced shifts could enhance future designs.

  12. The adsorption of chelating reagents on oxide minerals

    International Nuclear Information System (INIS)

    Bryson, M.A.W.

    1984-06-01

    This work constitutes a fundamental study of the interaction between chelating reagents and oxide minerals. The adsorption mechanisms have been elucidated for most of the systems generated by the oxides of copper(II) or iron(III) and chelating reagents octyl hydroxamate, N-phenylbenzohydroxamate, salicylaldoxime, 5-nitro-salicylaldoxime or 8-hydroxyquinoline. In order to better understand the adsorption process associated with copper(II) oxide, the oxide was recrystallized to produce a coarser material with a more uniform surface. This allowed the oxide surface to be viewed under the scanning electron microscope. A detailed investigation of the effect of the system variables; pH, conditioning period, concentration, temperature, surface area and dispersing reagent on the rate of precipitation of the copper chelate species of general form, Cu(chel) 2 , was made. In addition the chemical nature of the adsorbed species and the structural form of the precipitates were determined with the aid of infra-red spectroscopy and the scanning electron microscope. On the basis of these results a model has been formulated for the adsorption processes. The precipitation process was examined in more detail by the study of the adsorption of chelate on copper metal. Contact angle measurements of air bubbles on copper metal conditioned with chelate were related to the adsorption results in an attempt to isolate the optimum conditions for flotation of oxide minerals

  13. Chelation Treatment for Autism Spectrum Disorders: A Systematic Review

    Science.gov (United States)

    Davis, Tonya N.; O'Reilly, Mark; Kang, Soyeon; Lang, Russell; Rispoli, Mandy; Sigafoos, Jeff; Lancioni, Giulio; Copeland, Daelynn; Attai, Shanna; Mulloy, Austin

    2013-01-01

    Chelation treatment is used to eliminate specific metals from the body, such as mercury. It has been hypothesized that mercury poisoning may be a factor in autism and data suggest that perhaps 7% of individuals with autism spectrum disorder (ASD) have received chelation treatment. It would therefore seem timely to review studies investigating the…

  14. Development of Iron-Chelating Poly(ethylene terephthalate) Packaging for Inhibiting Lipid Oxidation in Oil-in-Water Emulsions.

    Science.gov (United States)

    Johnson, David R; Tian, Fang; Roman, Maxine J; Decker, Eric A; Goddard, Julie M

    2015-05-27

    Foods such as bulk oils, salad dressings, and nutritionally fortified beverages that are susceptible to oxidative degradation are often packaged in poly(ethylene terephthalate) (PET) bottles with metal chelators added to the food to maintain product quality. In the present work, a metal-chelating active packaging material is designed and characterized, in which poly(hydroxamic acid) (PHA) metal-chelating moieties were grafted from the surface of PET. Biomimetic PHA groups were grafted in a two-step UV-initiated process without the use of a photoinitiator. Surface characterization of the films by attenuated total reflective Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) suggested successful grafting and conversion of poly(hydroxyethyl acrylate) (PHEA) to PHA chelating moieties from the surface of PET. Colorimetric (ferrozine) and inductively coupled plasma mass spectroscopy (ICP-MS) assays demonstrated the ability of PET-g-PHA to chelate iron in a low-pH (3.0) environment containing a competitive metal chelator (citric acid). Lipid oxidation studies demonstrated the antioxidant activity of PET-g-PHA films in inhibiting iron-promoted oxidation in an acidified oil-in-water (O/W) emulsion model system (pH 3.0). Particle size and ζ-potential analysis indicated that the addition of PET-g-PHA films did not affect the physical stability of the emulsion system. This work suggests that biomimetic chelating moieties can be grafted from PET and effectively inhibit iron-promoted degradation reactions, enabling removal of metal-chelating additives from product formulations.

  15. Design, synthesis, and evaluation of polyhydroxamate chelators for selective complexation of actinides

    International Nuclear Information System (INIS)

    Gopalan, A.; Jacobs, H.; Koshti, N.; Stark, P.; Huber, V.; Dasaradhi, L.; Caswell, W.; Smith, P.; Jarvinen, G.

    1995-01-01

    Specific chelating polymers targeted for actinides have much relevance to problems involving remediation of nuclear waste. Goal is to develop polymer supported, ion specific extraction systems for removing actinides and other hazardous metal ions from wastewaters. This is part of an effort to develop chelators for removing actinide ions such as Pu from soils and waste streams. Selected ligands are being attached to polymeric backbones to create novel chelating polymers. These polymers and other water soluble and insoluble polymers have been synthesized and are being evaluated for ability to selectively remove target metal ions from process waste streams

  16. Mixed ligand chelate therapy for plutonium and toxic metals from energy power production. Final report, April 15, 1977-October 14, 1980

    International Nuclear Information System (INIS)

    Schubert, J.

    1980-01-01

    The results of experiments are summarized on the ability of combinations of chelating agents to modify the genotoxicity or tissue distributions. The mutagenicities of Cr and of chelating agents were determined. The metals described in the report are Pu(IV), Cd(II), Cr(III), and Cr(VI). Accurate measurements were made of the ability of CaNa 2 EDTA, CaNa 3 DTPA, and DMPS to reduce mortality in mice given doses (i.p.) of CdCl 2 well above the 100% lethal level. The efficacy in terms of the mmoles/kg needed to reduce the mortality was: DTPA > EDTA > DMPS. The combination of DTPA + DMPS proved most promising though little evidence for mixed complex formation was noted. Potentiometric titration studies the case of Pu(IV) a few combinations proved effective, but only when given shortly after Pu administration and then only in the liver but not the skeleton. It is recommended that metabolically stable chelating agents be used in combinations, especially for those combinations which may form very stable mixed ligand chelates

  17. Chelates for Micronutrient Nutrition among Crops

    Indian Academy of Sciences (India)

    years, it has been recognised that compounds containing che- lated metals could .... when using small amounts and no build up of harmful levels. ... degradation of iron chelates. .... down by soil microorganisms into much smaller units for ab-.

  18. Preparation, spectral, X-ray powder diffraction and computational studies and genotoxic properties of new azo-azomethine metal chelates

    Science.gov (United States)

    Bitmez, Şirin; Sayin, Koray; Avar, Bariş; Köse, Muhammet; Kayraldız, Ahmet; Kurtoğlu, Mükerrem

    2014-11-01

    A new tridentate azo-azomethine ligand, N‧-[{2-hydroxy-5-[(4-nitrophenyl)diazenyl]phenyl}methylidene]benzohydrazidemonohydrate, (sbH·H2O) (1), is prepared by condensation of benzohydrazide and 2-hydroxy-5-[(4-nitrophenyl)diazenyl]benzaldehyde (a) with treatment of a solution of diazonium salt of p-nitroaniline and 2-hydroxybenzaldehyde in EtOH. The five coordination compounds, [Co(sb)2]·4H2O (2), [Ni(sb)2]·H2O (3), [Cu(sb)2]·4H2O (4), [Zn(sb)2]·H2O (5) and [Cd(sb)2]·H2O (6) are prepared by reacting the Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) ions with the ligand. The structures of the compounds are elucidated from the elemental analyses data and spectroscopic studies. It is found the ligand acts as a tridentate bending through phenolic and carbonyl oxygens and nitrogen atom of the Cdbnd Nsbnd group similar to the most of salicylaldimines. Comparison of the infrared spectra of the ligand and its metal complexes confirm that azo-Schiff base behaves as a monobasic tridentate ligand towards the central metal ion with an ONO donor sequence. Upon complexation with the ligand, the Cd(II), and Zn(II) ions form monoclinic structures, while Co(II), Cu(II) and Ni(II) ions form orthorhombic structures. Quantum chemical calculations are performed on tautomers and its metal chelates by using DFT/B3LYP method. Most stable tautomer is determined as tautomer (1a). The geometrical parameters of its metal chelates are obtained as theoretically. The NLO properties of tautomer (1a) and its metal complexes are investigated. Finally, the ligand and its metal complexes are assessed for their genotoxicity.

  19. 3-hydroxy-2(1H)-pyridinone chelating agents

    Science.gov (United States)

    Raymond, K.; Xu, J.

    1999-04-06

    Disclosed is a series of improved chelating agents and the chelates formed from these agents, which are highly effective upon both injection and oral administration. Several of the most effective are of low toxicity. These chelating agents incorporate within their structure 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy group of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity, as well as the chemical stability towards oxidation and reduction, of the hydroxypyridinones. In the metal complexes of the chelating agents, the amide protons form very strong hydrogen bonds with the adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provide a certain degree of lipophilicity to the 3,2-HOPO, increasing oral activity. 2 figs.

  20. The use of a biodegradable chelator for enhanced phytoextraction of heavy metals by Festuca arundinacea from municipal solid waste compost and associated heavy metal leaching.

    Science.gov (United States)

    Zhao, Shulan; Jia, Lina; Duo, Lian

    2013-02-01

    In a column experiment with horizontal permeable barriers, the effects of a biodegradable chelator-nitrilotriacetic acid (NTA) on the uptake of heavy metals from municipal solid waste (MSW) compost by Festuca arundinacea and metal leaching were investigated. The use of NTA was effective in increasing Cu, Pb, and Zn uptakes in shoots of two crops of F. arundinacea. In columns with barriers and treated with 20 mmol NTA per kg MSW compost, metal uptakes by the first and second crop of F. arundinacea were, respectively, 3.8 and 4.0 times for Pb, and 1.8 and 1.7 times for Zn greater with the added NTA than without it. Though NTA application mobilized metals, it caused only slight leaching of metals from MSW compost. Permeable barriers positioned between compost and soil effectively reduced metal leaching. NTA-assisted phytoextraction by turfgrass with permeable barriers to cleanup heavy metal contaminated MSW compost should be environmentally safe. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Hydroxynaphthyridine-derived group III metal chelates: wide band gap and deep blue analogues of green Alq3 (tris(8-hydroxyquinolate)aluminum) and their versatile applications for organic light-emitting diodes.

    Science.gov (United States)

    Liao, Szu-Hung; Shiu, Jin-Ruei; Liu, Shun-Wei; Yeh, Shi-Jay; Chen, Yu-Hung; Chen, Chin-Ti; Chow, Tahsin J; Wu, Chih-I

    2009-01-21

    A series of group III metal chelates have been synthesized and characterized for the versatile application of organic light-emitting diodes (OLEDs). These metal chelates are based on 4-hydroxy-1,5-naphthyridine derivates as chelating ligands, and they are the blue version analogues of well-known green fluorophore Alq(3) (tris(8-hydroxyquinolinato)aluminum). These chelating ligands and their metal chelates were easily prepared with an improved synthetic method, and they were facially purified by a sublimation process, which enables the materials to be readily available in bulk quantity and facilitates their usage in OLEDs. Unlike most currently known blue analogues of Alq(3) or other deep blue materials, metal chelates of 4-hydroxy-1,5-naphthyridine exhibit very deep blue fluorescence, wide band gap energy, high charge carrier mobility, and superior thermal stability. Using a vacuum-thermal-deposition process in the fabrication of OLEDs, we have successfully demonstrated that the application of these unusual hydroxynaphthyridine metal chelates can be very versatile and effective. First, we have solved or alleviated the problem of exciplex formation that took place between the hole-transporting layer and hydroxynaphthyridine metal chelates, of which OLED application has been prohibited to date. Second, these deep blue materials can play various roles in OLED application. They can be a highly efficient nondopant deep blue emitter: maximum external quantum efficiency eta(ext) of 4.2%; Commision Internationale de L'Eclairage x, y coordinates, CIE(x,y) = 0.15, 0.07. Compared with Alq(3), Bebq(2) (beryllium bis(benzoquinolin-10-olate)), or TPBI (2,2',2''-(1,3,5-phenylene)tris(1-phenyl-1H-benzimidazole), they are a good electron-transporting material: low HOMO energy level of 6.4-6.5 eV and not so high LUMO energy level of 3.0-3.3 eV. They can be ambipolar and possess a high electron mobility of 10(-4) cm(2)/V s at an electric field of 6.4 x 10(5) V/cm. They are a

  2. Mixed and chelated waste test programs with bitumen solidification

    International Nuclear Information System (INIS)

    Simpson, S.I.; Morris, M.; Vidal, H.

    1988-01-01

    This paper presents the results of bitumen solidification tests on mixed wastes and chelated wastes. The French Atomic Energy Commission (CEA) performed demonstration tests on radioactive wastes contaminated with chelating agents for Associated Technologies, Inc. (ATI). The chelated wastes were produced and concentrated by Commonwealth Edison Co. as a result of reactor decontamination at Dresden Nuclear Station, Unit 1. Law Engineering in Charlotte, N. C. produced samples and performed tests on simulated heavy metal laden radioactive waste (mixed) to demonstrate the quality of the bituminous product. The simulation is intended to represent waste produced at Oak Ridge National Labs operated by Martin-Marietta

  3. Selectivity in extraction of copper and indium with chelate extractants

    International Nuclear Information System (INIS)

    Zivkovic, D.

    2003-01-01

    Simultaneous extraction of copper and indium with chelate extractants (LIX84 and D2E11PA) was described. Stechiometry of metal-organic complexes examined using the method of equimolar ratios resulted in CuR 2 and InR 3 forms of hydrophobic extracting species. A linear correlation was obtained between logarithm of distribution coefficients and chelate agents and pH, respectively. Selectivity is generally higher with higher concentrations of chelate agents in the organic phase, and is decreased with increase of concentration of hydrogen ions in feeding phase. (Original)

  4. Metal Chelation as a Powerful Strategy to Probe Cellular Circuitry Governing Fungal Drug Resistance and Morphogenesis.

    Directory of Open Access Journals (Sweden)

    Elizabeth J Polvi

    2016-10-01

    metal chelation modulates morphogenetic circuitry and echinocandin resistance, and illuminate a novel facet to metal homeostasis at the host-pathogen interface, with broad therapeutic potential.

  5. Copper and Zinc Chelation as a Treatment of Alzheimer's Disease

    Science.gov (United States)

    Hodak, Miroslav; Bernholc, Jerry

    2014-03-01

    Alzheimer's disease (AD) is a neurodegenerative disorder affecting millions of people in the U.S. The cause of the disease remains unknown, but amyloid- β (A β), a short peptide, is considered causal its pathogenesis. At cellular level, AD is characterized by deposits mainly composed of A β that also contain elevated levels of transition metals ions. Targeting metals is a promising new strategy for AD treatment, which uses moderately strong metal chelators to sequester them from A β or the environment. PBT2 is a chelating compound that has been the most promising in clinical trials. In our work, we use computer simulations to investigate complexes of a close analog of PBT2 with Cu2+ and Zn2+ ions. The calculations employ KS/FD DFT method, which combines Kohn-Sham DFT with the frozen-density DFT to achieve efficient description of explicit solvent beyond the first solvation shell. Our work is based on recent experiments and examines both 1:1 and 2:1 chelator-metal stochiometries detected experimentally. The results show that copper attaches more strongly than zinc, find that 1:1 complexes involve water in the first coordination shell and determine which one of several possible 2:1 geometries is the most preferable.

  6. Chelation of heavy group 2 (radio)metals by p-tert-butylcalix[4]arene-1,3-crown-6 and logK determination via NMR

    Science.gov (United States)

    Bauer, David; Gott, Matthew; Steinbach, Jörg; Mamat, Constantin

    2018-06-01

    A crown-bridged calix[4]arene scaffold was investigated as lead compound for the ligation of heavy alkaline earth metals such as strontium and barium, which appear to be useful for radiopharmaceutical applications in diagnosis as well as in radiotherapy. In particular barium, due to its chemical similarities, could serve as a surrogate for radium, a metal of high radiopharmaceutical interest. The ability of p-tert-butylcalix[4]arene-1,3-crown-6 (1) in particular to chelate cations, such as group 1 and 2 metal ions or ammonium ions is well known. Also, the manifold possibilities of structural modification on the upper- and lower-rim as well as on the crown itself produce properties that may lead to a highly selective and effective chelating agent. In this work, titration experiments of the perchlorate salts of Ba2+, Sr2+ and Pb2+ with ligand 1 were performed to determine their stability constants (logK = 4.7, 4.3, and 3.3, respectively) by 1H NMR measurements in acetonitrile-d3.

  7. Copper chelators: chemical properties and bio-medical applications.

    Science.gov (United States)

    Tegoni, M; Valensin, D; Toso, L; Remelli, M

    2014-01-01

    Copper is present in different concentrations and chemical forms throughout the earth crust, surface and deep water and even, in trace amounts, in the atmosphere itself. Copper is one of the first metals used by humans, the first artifacts dating back 10,000 years ago. Currently, the world production of refined copper exceeds 16,000 tons/year. Copper is a micro-element essential to life, principally for its red-ox properties that make it a necessary cofactor for many enzymes, like cytochrome-c oxidase and superoxide dismutase. In some animal species (e.g. octopus, snails, spiders, oysters) copper-hemocyanins also act as carriers of oxygen instead of hemoglobin. However, these red-ox properties also make the pair Cu(+)/Cu(2+) a formidable catalyst for the formation of reactive oxygen species, when copper is present in excess in the body or in tissues. The treatment of choice in cases of copper overloading or intoxication is the chelation therapy. Different molecules are already in clinical use as chelators or under study or clinical trial. It is worth noting that chelation therapy has also been suggested to treat some neurodegenerative diseases or cardiovascular disorders. In this review, after a brief description of the homeostasis and some cases of dyshomeostasis of copper, the main (used or potential) chelators are described; their properties in solution, even in relation to the presence of metal or ligand competitors, under physiological conditions, are discussed. The legislation of the most important Western countries, regarding both the use of chelating agents and the limits of copper in foods, drugs and cosmetics, is also outlined.

  8. The use of chelating ion exchanger in conjunction with radioisotope X-ray spectrometry for determination of trace amounts of metals in water

    International Nuclear Information System (INIS)

    Holynska, B.

    1974-01-01

    The chelating ion exchange resin Chelex-100 has been applied for collection of trace amounts of several metal ions from water solutions. The kinetics of the exchange reaction has been measured, as well as the influence of pH of the solution and Ca or Na ion concentrations on the metal collection. The radioisotope X-ray fluorescence method has been applied for determination of metal ions absorbed in the resin. The estimated limit of determination is 0.01 ppm for Fe 3+ , Zn 2+ , Cu 2+ , Hg 2+ , Pb 2+ and Cd 2+ . Total error (1 s) of the method varied from 3 to 15% depending on the metal concentration. (author)

  9. Controlling lipid oxidation via a biomimetic iron chelating active packaging material.

    Science.gov (United States)

    Tian, Fang; Decker, Eric A; Goddard, Julie M

    2013-12-18

    Previously, a siderophore-mimetic metal chelating active packaging film was developed by grafting poly(hydroxamic acid) (PHA) from the surface of polypropylene (PP) films. The objective of the current work was to demonstrate the potential applicability of this PP-g-PHA film to control iron-promoted lipid oxidation in food emulsions. The iron chelating activity of this film was investigated, and the surface chemistry and color intensity of films were also analyzed after iron chelation. In comparison to the iron chelating activity in the free Fe(3+) solution, the PP-g-PHA film retained approximately 50 and 30% of its activity in nitrilotriacetic acid (NTA)/Fe(3+) and citric acid/Fe(3+) solutions, respectively (pH 5.0), indicating a strong chelating strength for iron. The ability of PP-g-PHA films to control lipid oxidation was demonstrated in a model emulsion system (pH 3.0). PP-g-PHA films performed even better than ethylenediaminetetraacetic acid (EDTA) in preventing the formation of volatile oxidation products. The particle size and ζ potential results of emulsions indicated that PP-g-PHA films had no adverse effects on the stability of the emulsion system. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis suggested a non-migratory nature of the PP-g-PHA film surface. These results suggest that such biomimetic, non-migratory metal chelating active packaging films have commercial potential in protecting foods against iron-promoted lipid oxidation.

  10. Functionalized dithiocarbamate chelating resin for the removal of Co2+ from simulated wastewater

    Science.gov (United States)

    Shi, Xuewei; Fu, Linwei; Wu, Yanyang; Zhao, Huiling; Zhao, Shuangliang; Xu, Shouhong

    2017-12-01

    Industrial wastewater that contains trace amounts of heavy metal ions is often seen in petrochemical industry. While this wastewater can not be directly discharged, it is difficult to treat due to the low concentration of metal ions. Introducing chelating reagents into this wastewater for selective ion adsorption, followed by a mechanical separation process, provides an appealing solution. Toward the success of this technology, the development of effective chelating resins is of key importance. In the present work, a chelating resin containing amino and dithiocarbamate groups was reported for the removal of Co(II) metal ions in trace concentrations from simulated wastewater. By investigating the adsorption performance of the chelating resin at different solution pH values, adsorbent dosages, contact time, initial ion concentrations, and adsorption temperatures, the maximum adsorption capacity of the resin for Co(II) was identified to be 24.89 mg g-1 for a 2 g L-1 adsorbent dosage and a pH value of 5. After four adsorption-desorption cycles, 97% of the adsorption capacity of the resin was maintained. The adsorption kinetics and thermodynamics were analyzed and discussed as well.

  11. The assembly of metals chelation by thiols and vacuolar compartmentalization conferred increased tolerance to and accumulation of cadmium and arsenic in transgenic Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Guo, Jiangbo; Xu, Wenzhong; Ma, Mi

    2012-01-01

    Highlights: ► Simultaneous transformation of AsPCS1 and ScYCF1 into Arabidopsis thaliana which is sensitive to heavy metals, leads to transgenic plants tolerant to Arsenic and cadmium. ► Dual-gene transgenic Arabidopsis showed higher accumulation of Arsenic and cadmium than single and non-transgenic plants. ► Our results proved that improved thiol peptides synthesis and vacuolar compartmentation in plant dramatically boosted the survival rates of plants when exposed to heavy metals. ► A new strategy for efficient phytoremediation of heavy metals by stacking genes transformation in plants was developed in this article. - Abstract: Transgenic Arabidopsis thaliana were developed to increase tolerance for and accumulation of heavy metals and metalloids by simultaneous overexpression of AsPCS1 and YCF1 (derived from garlic and baker's yeast) based on the fact that chelation of metals and vacuolar compartmentalization are the main strategies for heavy metals/metalloids detoxification and tolerance in plants. Dual-gene transgenic lines had the longest roots and the highest accumulation of Cd and As than single-gene transgenic lines and wildtype. When grown on cadmium or arsenic (arsenite/arsenate), Dual-gene transgenic lines accumulated over 2–10 folds cadmium/arsenite and 2–3 folds arsenate than wild type or plants expressing AsPCS1 or YCF1 alone. Such stacking modified genes involved in chelation of toxic metals and vacuolar compartmentalization represents a highly promising new tool for use in phytoremediation efforts.

  12. Assessment of the Efficacy of Chelate-Assisted Phytoextraction of Lead by Coffeeweed (Sesbania exaltata Raf.

    Directory of Open Access Journals (Sweden)

    Gloria Miller

    2008-12-01

    Full Text Available Lead (Pb, depending upon the reactant surface, pH, redox potential and other factors can bind tightly to the soil with a retention time of many centuries. Soil-metal interactions by sorption, precipitation and complexation processes, and differences between plant species in metal uptake efficiency, transport, and susceptibility make a general prediction of soil metal bioavailability and risks of plant metal toxicity difficult. Moreover, the tight binding characteristic of Pb to soils and plant materials make a significant portion of Pb unavailable for uptake by plants. This experiment was conducted to determine whether the addition of ethylenediaminetetraacetic acid (EDTA, ethylene glycol tetraacetic acid (EGTA, or acetic acid (HAc can enhance the phytoextraction of Pb by making the Pb soluble and more bioavailable for uptake by coffeeweed (Sesbania exaltata Raf.. Also we wanted to assess the efficacy of chelates in facilitating translocation of the metal into the above-ground biomass of this plant. To test the effect of chelates on Pb solubility, 2 g of Pb-spiked soil (1000 mg Pb/kg dry soil were added to each 15 mL centrifuge tube. Chelates (EDTA, EGTA, HAc in a 1:1 ratio with the metal, or distilled deionized water were then added. Samples were shaken on a platform shaker then centrifuged at the end of several time periods. Supernatants were filtered with a 0.45 μm filter and quantified by inductively coupled plasma-optical emission spectrometry (ICP-OES to determine soluble Pb concentrations. Results revealed that EDTA was the most effective in bringing Pb into solution, and that maximum solubility was reached 6 days after chelate amendment. Additionally, a greenhouse experiment was conducted by planting Sesbania seeds in plastic tubes containing top soil and peat (2:1, v:v spiked with various levels (0, 1000, 2000 mg Pb/kg dry soil of lead nitrate. At six weeks after emergence, aqueous solutions of EDTA and/or HAc (in a 1:1 ratio

  13. Effect of electrostatic charge in plastic spacers on the lung delivery of HFA-salbutamol in children

    DEFF Research Database (Denmark)

    Anhøj, J; Bisgaard, H; Lipworth, B J

    1999-01-01

    delivered a significantly (Pplastic spacers reduces lung dose in children by more than two-fold. This is clinically significant and the use of potentially electrostatically charged......AIMS: The effect of the electrostatic charge in plastic spacers in vivo on drug delivery to the lung of hydrofluoroalkane (HFA) salbutamol spray was studied in children. METHODS: Five children, aged 7-12 years, were included in a 3-way crossover randomised single-blind trial. Salbutamol HFA spray...... was delivered on 3 different study days from plastic spacers with mouthpiece. Pre-treatment of the spacers differed between study days: (a) Non-electrostatic 350 ml Babyhaler (coated with benzalkonium chloride) (b) New 350 ml Babyhaler (rinsed in water), and (c) New 145 ml AeroChamber (rinsed in water). Plasma...

  14. New fluorescent azo-Schiff base Cu(II) and Zn(II) metal chelates; spectral, structural, electrochemical, photoluminescence and computational studies

    Science.gov (United States)

    Purtas, Fatih; Sayin, Koray; Ceyhan, Gokhan; Kose, Muhammet; Kurtoglu, Mukerrem

    2017-06-01

    A new Schiff base containing azo chromophore group obtained by condensation of 2-hydroxy-4-[(E)-phenyldiazenyl]benzaldehyde with 3,4-dimethylaniline (HL) are used for the syntheses of new copper(II) and zinc(II) chelates, [Cu(L)2], and [Zn(L)2], and characterized by physico-chemical and spectroscopic methods such as 1H and 13C NMR, IR, UV.-Vis. and elemental analyses. The solid state structure of the ligand was characterized by single crystal X-ray diffraction study. X-ray diffraction data was then used to calculate the harmonic oscillator model of aromaticity (HOMA) indexes for the rings so as to investigate of enol-imine and keto-amine tautomeric forms in the solid state. The phenol ring C10-C15 shows a considerable deviation from the aromaticity with HOMA value of 0.837 suggesting the shift towards the keto-amine tautomeric form in the solid state. The analytical data show that the metal to ligand ratio in the chelates was found to be 1:2. Theoretical calculations of the possible isomers of the ligand and two metal complexes are performed by using B3LYP method. Electrochemical and photoluminescence properties of the synthesized azo-Schiff bases were also investigated.

  15. Speciation in Metal Toxicity and Metal-Based Therapeutics

    Directory of Open Access Journals (Sweden)

    Douglas M. Templeton

    2015-04-01

    Full Text Available Metallic elements, ions and compounds produce varying degrees of toxicity in organisms with which they come into contact. Metal speciation is critical to understanding these adverse effects; the adjectives “heavy” and “toxic” are not helpful in describing the biological properties of individual elements, but detailed chemical structures are. As a broad generalization, the metallic form of an element is inert, and the ionic salts are the species that show more significant bioavailability. Yet the salts and other chelates of a metal ion can give rise to quite different toxicities, as exemplified by a range of carcinogenic potential for various nickel species. Another important distinction comes when a metallic element is organified, increasing its lipophilicity and hence its ability to penetrate the blood brain barrier, as is seen, for example, with organic mercury and tin species. Some metallic elements, such as gold and platinum, are themselves useful therapeutic agents in some forms, while other species of the same element can be toxic, thus focusing attention on species interconversions in evaluating metal-based drugs. The therapeutic use of metal-chelating agents introduces new species of the target metal in vivo, and this can affect not only its desired detoxification, but also introduce a potential for further mechanisms of toxicity. Examples of therapeutic iron chelator species are discussed in this context, as well as the more recent aspects of development of chelation therapy for uranium exposure.

  16. Studies on effect of Microbial Iron Chelators on Candida Albican

    International Nuclear Information System (INIS)

    Rehmani, Fouzia S.; Milicent, S.; Zaheer-Uddin

    2005-01-01

    Iron is an essential for the life of all microbe cells. It generally exists in the oxidized form Fe(III). Even under anaerobic reducing condition the metal appear to be taken up as Fe(III). Thus free-living microorganisms require specific and effective ferric ion transport system to cope with low availability of the metal. In iron deficient environment they produce a low molecular weight specific chelators called siderphores or microbial iron chelators. Siderphores compete for limited supplied of iron. These compounds came out of the cell but can not re-enter without iron due to high affinity of these siderphores often have more than one catechol/hydroxamate functions and are multidentate (usually hexadentate ligands). The aim of the present research is to check the effect of iron chelators, namely gallic acid and salisyl hydroxamate on the growth of Candida albican in vitro. C. albican is the opportunistic paltogen present as the normal flora inside human body. In vivo the growth of C. albican is distributed by the use of antibiotics and immuno suppressers. In cases of iron over-dosage in human being, the patients are treated with certain a-iron chelators. Hence an attempt is made to notice the effect that might be inhibition or enhancement of the organism in vitro. (author)

  17. Studies on chelation properties of ampicillin with trace metal ions and comparison with penicillin complexes

    International Nuclear Information System (INIS)

    Rehmani, F.S.; Hameed, W.

    2003-01-01

    The penicillin is highly effective antibiotic with extremely wide margin of safety. Ampicillin e is the penicillin group of antibiotic in which side chain is phenyl group i.e. D-amino benzyl penicillin. The side chain determines many of anti bacterial and pharmacological characteristics. They inhibit the protein synthesis in bacterial cell wall. The chelating properties of the antibiotic may be used in the metal transport across the membrane. The present investigations are helpful in drug metabolism and their effects on minerals contents of the body. The complex formation between Ampicillin and penicillin with trace metal ions such as Fe(III), Cr(III), Al(III), Mn(II), Ni(II), Co(II), Ca(II), Mg(II), Cu(III) and Zn(II) were studied by potentiometric titrations and spectrophotometric methods. Stoichiometry of these complexes were studied by mole ratio method. It was found that the Fe(III) and Cu(II) ions form most stable complexes near physiological pH and the mole ratio was 1:1. (author)

  18. Effect of some colloid surfactants on spectrophotometric characteristics of metal chelates with chromophore organic reagents

    International Nuclear Information System (INIS)

    Chernova, R.K.

    1977-01-01

    Theoretical regularities and prospects of using surface active substances (SAS) in spectrophotometric determination of metal ions (including ions of rare-earth elements, transition metals, Be(3)) with chromophore chelating reagents were investigated. The chromophore reagents investigated were pyrocatechol violet, phenolcarboxylic acids of the triarylmethane series, fluorones, phthalexones and azo-compounds. As SAS certain long-chain quaternary ammonium and pyridinium salts (LQAS) were employed. From the results reported it follows that the introduction of LQAS in the system of Mesup(n+)-chromophore reagent is a rather effective method of enhancing the contrast rendition and, in some cases, the sensitivity and selectivity of the reagents. Explanations are suggested as to the factors which cause the changes observed in the contrast of the reactions in the presence of SAS; the underlying phenomena are the ligand-ligand interactions between the organic reagents and SAS and solubilization processes of the reaction products by the micelles of SAS

  19. Investigation on the influence of metal ion impurities on the complexation behavior of generator produced {sup 90}Y with different bifunctional chelators

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Usha; Gamre, Naresh; Chakravarty, Rubel; Pillai, Maroor Raghavan Ambikalmajan; Dash, Ashutosh [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Radiopharmaceuticals Div.

    2014-07-01

    While the {sup 90}Sr/{sup 90}Y generator is the exclusive source of obtaining 'no carrier added' {sup 90}Y for targeted therapy, the presence of trace metals in the radiolabeling solutions poses a serious challenge owing to their ability to diminish the {sup 90}Y complexation yields with bifunctional chelators (BFCs). p-SCN-Bn-PCTA is a novel ligand having faster complexation kinetics with a number of radiometals. In this work, a systematic investigation was performed to evaluate the chelating ability of p-SCN-Bn-PCTA for {sup 90}Y and the influence of trace metal ions on it's complexation with {sup 90}Y in comparison to p-SCN-Bn-DTPA and p-SCN-Bn-DOTA using {sup 90}YCl{sub 3} obtained from an electrochemical generator. Results from our study indicate that while p-SCN-Bn-PCTA gave very good radiolabeling yields with {sup 90}Y when the reaction was carried out by heating for few minutes, it was most sensitive to the presence of trace metals, especially Fe(III). An independent and useful observation is that p-SCN-Bn-PCTA could be considered as the ligand of choice for assessing the chemical purity of generator derived {sup 90}Y.

  20. Impact of two iron(III) chelators on the iron, cadmium, lead and nickel accumulation in poplar grown under heavy metal stress in hydroponics.

    Science.gov (United States)

    Mihucz, Victor G; Csog, Árpád; Fodor, Ferenc; Tatár, Enikő; Szoboszlai, Norbert; Silaghi-Dumitrescu, Luminiţa; Záray, Gyula

    2012-04-15

    Poplar (Populus jacquemontiana var. glauca cv. Kopeczkii) was grown in hydroponics containing 10 μM Cd(II), Ni(II) or Pb(II), and Fe as Fe(III) EDTA or Fe(III) citrate in identical concentrations. The present study was designed to compare the accumulation and distribution of Fe, Cd, Ni and Pb within the different plant compartments. Generally, Fe and heavy-metal accumulation were higher by factor 2-7 and 1.6-3.3, respectively, when Fe(III) citrate was used. Iron transport towards the shoot depended on the Fe(III) chelate and, generally, on the heavy metal used. Lead was accumulated only in the root. The amounts of Fe and heavy metals accumulated by poplar were very similar to those of cucumber grown in an identical way, indicating strong Fe uptake regulation of these two Strategy I plants: a cultivar and a woody plant. The Strategy I Fe uptake mechanism (i.e. reducing Fe(III) followed by Fe(II) uptake), together with the Fe(III) chelate form in the nutrient solution had significant effects on Fe and heavy metal uptake. Poplar appears to show phytoremediation potential for Cd and Ni, as their transport towards the shoot was characterized by 51-54% and 26-48% depending on the Fe(III) supply in the nutrient solution. Copyright © 2012 Elsevier GmbH. All rights reserved.

  1. The assembly of metals chelation by thiols and vacuolar compartmentalization conferred increased tolerance to and accumulation of cadmium and arsenic in transgenic Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiangbo [Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093 (China); Inner Mongolia Key Laboratory of Biomass-Energy Conversion, The Institute of Bioengineering and Technology, Inner Mongolia University of Science and Technology, Baotou 040100 (China); Xu, Wenzhong [Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093 (China); Ma, Mi, E-mail: mami@ibcas.ac.cn [Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093 (China)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Simultaneous transformation of AsPCS1 and ScYCF1 into Arabidopsis thaliana which is sensitive to heavy metals, leads to transgenic plants tolerant to Arsenic and cadmium. Black-Right-Pointing-Pointer Dual-gene transgenic Arabidopsis showed higher accumulation of Arsenic and cadmium than single and non-transgenic plants. Black-Right-Pointing-Pointer Our results proved that improved thiol peptides synthesis and vacuolar compartmentation in plant dramatically boosted the survival rates of plants when exposed to heavy metals. Black-Right-Pointing-Pointer A new strategy for efficient phytoremediation of heavy metals by stacking genes transformation in plants was developed in this article. - Abstract: Transgenic Arabidopsis thaliana were developed to increase tolerance for and accumulation of heavy metals and metalloids by simultaneous overexpression of AsPCS1 and YCF1 (derived from garlic and baker's yeast) based on the fact that chelation of metals and vacuolar compartmentalization are the main strategies for heavy metals/metalloids detoxification and tolerance in plants. Dual-gene transgenic lines had the longest roots and the highest accumulation of Cd and As than single-gene transgenic lines and wildtype. When grown on cadmium or arsenic (arsenite/arsenate), Dual-gene transgenic lines accumulated over 2-10 folds cadmium/arsenite and 2-3 folds arsenate than wild type or plants expressing AsPCS1 or YCF1 alone. Such stacking modified genes involved in chelation of toxic metals and vacuolar compartmentalization represents a highly promising new tool for use in phytoremediation efforts.

  2. Competition of dipositive metal ions for Fe (III) binding sites in chelation therapy of Iron Load

    International Nuclear Information System (INIS)

    Rehmani, Fouzia S.

    2005-01-01

    Iron overload is a condition in which excessive iron deposited in the liver, kidney and spleen of human beings in the patients of beta thalassemia and sickle cell anemia. Instead of its importance iron could be toxic when in excess, it damages the tissues. For the treatment of iron overload, a drug desferrioxamine mesylate has been used. It is linear trihydroxamic acid, a natural siderophore produced by streptomyces which removes the extra iron from body. Salicylhydroxamate type siderphore. In present research salicylhydroxamate was used for the complexation with dipositive metal ions which are available in biological environments such as Mn (II), Co (II), Ni (II) and Cu (II). The aim of our work was to study the competition reactions between Fe (III) and other dipositive ions; to calculate the thermodynamic data of chelation of these metal ions complexes with hydroxamate by computer program and comparison with hydroxamate complexes. (author)

  3. Enhanced in vitro activity of tigecycline in the presence of chelating agents.

    Science.gov (United States)

    Deitchman, Amelia N; Singh, Ravi Shankar Prasad; Rand, Kenneth H; Derendorf, Hartmut

    2018-05-01

    The lack of availability of novel antibiotic agents and the rise of resistance to existing therapies has led clinicians to utilise combination therapy to adequately treat bacterial infections. Here we examined how chelators may impact the in vitro activity of tigecycline (TIG) against Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. Minimum inhibitory concentrations (MICs) were determined by broth dilution with and without various combinations of chelators (EDTA and other tetracyclines) and metal ions (i.e. calcium, magnesium). Trimethoprim (TMP) was used as a non-chelating control. Addition of metal ions led to increases in MICs, whilst addition of EDTA led to decreases in MICs. The chelating effects of EDTA were reversed by addition of magnesium and most profoundly calcium. Similar effects of EDTA and calcium were observed for tetracycline (TET) and TMP. When other tetracyclines (TET, oxytetracycline (OXY) and chlortetracycline (CHL)) were used as chelators at concentrations below their MICs, TIG MICs decreased for P. aeruginosa but not for E. coli. Some decreases in TIG MICs were observed for K. pneumoniae when TET and CHL were added. A dose-dependent decrease in TIG MIC was observed for TET and was reversed by the addition of calcium. The presence of effects of EDTA and calcium on TMP MICs indicates that mechanisms outside of TIG chelation likely play a role in enhanced activity. Full characterisation of an unexpected interaction such as TIG-TET with different microorganisms could provide valuable insights into the underlying mechanisms and design of physiologically viable chelators as candidates for future combinations regimens. Copyright © 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  4. Influence of direct and alternating current electric fields on efficiency promotion and leaching risk alleviation of chelator assisted phytoremediation.

    Science.gov (United States)

    Luo, Jie; Cai, Limei; Qi, Shihua; Wu, Jian; Sophie Gu, Xiaowen

    2018-03-01

    Direct and alternating current electric fields with various voltages were used to improve the decontamination efficiency of chelator assisted phytoremediation for multi-metal polluted soil. The alleviation effect of electric field on leaching risk caused by chelator application during phytoremediation process was also evaluated. Biomass yield, pollutant uptake and metal leaching retardation under alternating current (AC) and direct current (DC) electric fields were compared. The biomass yield of Eucalyptus globulus under AC fields with various voltages (2, 4 and 10 V) were 3.91, 4.16 and 3.67kg, respectively, significantly higher than the chelator treatment without electric field (2.71kg). Besides growth stimulation, AC fields increased the metal concentrations of plant tissues especially in aerial parts manifested by the raised translocation factor of different metals. Direct current electric fields with low and moderate voltages increased the biomass production of the species to 3.45 and 3.12kg, respectively, while high voltage on the contrary suppressed the growth of the plants (2.66kg). Under DC fields, metal concentrations elevated obviously with increasing voltages and the metal translocation factors were similar under all voltages. Metal extraction per plant achieved the maximum value under moderate voltage due to the greatest biomass production. DC field with high voltage (10V) decreased the volume of leachate from the chelator treatment without electric field from 1224 to 56mL, while the leachate gathered from AC field treatments raised from 512 to 670mL. DC field can retard the downward movement of metals caused by chelator application more effectively relative to AC field due to the constant water flow and electroosmosis direction. Alternating current field had more promotive effect on chelator assisted phytoremediation efficiency than DC field illustrated by more metal accumulation in the species. However, with the consideration of leaching risk, DC

  5. An off-line automated preconcentration system with ethylenediaminetriacetate chelating resin for the determination of trace metals in seawater by high-resolution inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Minami, Tomoharu; Konagaya, Wataru; Zheng, Linjie; Takano, Shotaro; Sasaki, Masanobu; Murata, Rena; Nakaguchi, Yuzuru; Sohrin, Yoshiki

    2015-01-07

    A novel automated off-line preconcentration system for trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in seawater was developed by improving a commercially available solid-phase extraction system SPE-100 (Hiranuma Sangyo). The utilized chelating resin was NOBIAS Chelate-PA1 (Hitachi High-Technologies) with ethylenediaminetriacetic acid and iminodiacetic acid functional groups. Parts of the 8-way valve made of alumina and zirconia in the original SPE-100 system were replaced with parts made of polychlorotrifluoroethylene in order to reduce contamination of trace metals. The eluent pass was altered for the back flush elution of trace metals. We optimized the cleaning procedures for the chelating resin column and flow lines of the preconcentration system, and developed a preconcentration procedure, which required less labor and led to a superior performance compared to manual preconcentration (Sohrin et al.). The nine trace metals were simultaneously and quantitatively preconcentrated from ∼120 g of seawater, eluted with ∼15 g of 1M HNO3, and determined by HR-ICP-MS using the calibration curve method. The single-step preconcentration removed more than 99.998% of Na, K, Mg, Ca, and Sr from seawater. The procedural blanks and detection limits were lower than the lowest concentrations in seawater for Mn, Ni, Cu, and Pb, while they were as low as the lowest concentrations in seawater for Al, Fe, Co, Zn, and Cd. The accuracy and precision of this method were confirmed by the analysis of reference seawater samples (CASS-5, NASS-5, GEOTRACES GS, and GD) and seawater samples for vertical distribution in the western North Pacific Ocean. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. MULTIDENTATE TEREPHTHALAMIDATE AND HYDROXYPYRIDONATE LIGANDS: TOWARDS NEW ORALLY ACTIVE CHELATORS

    Energy Technology Data Exchange (ETDEWEB)

    Abergel, Rebecca J.; Raymond, Kenneth N.

    2011-07-13

    The limitations of current therapies for the treatment of iron overload or radioisotope contamination have stimulated efforts to develop new orally bioavailable iron and actinide chelators. Siderophore-inspired tetradentate, hexadentate and octadentate terephthalamidate and hydroxypyridonate ligands were evaluated in vivo as selective and efficacious iron or actinide chelating agents, with several metal loading and ligand assessment procedures, using {sup 59}Fe, {sup 238}Pu, and {sup 241}Am as radioactive tracers. The compounds presented in this study were compared to commercially available therapeutic sequestering agents [deferoxamine (DFO) for iron and diethylenetriaminepentaacetic acid (DPTA) for actinides] and are unrivaled in terms of affinity, selectivity and decorporation efficacy, which attests to the fact that high metal affinity may overcome the low bioavailability properties commonly associated to multidenticity.

  7. Effect of chelating agents and metal ions on nickel bioavailability and chlorophyll fluorescence response in wheat- An approach for attenuation of Ni stress

    Directory of Open Access Journals (Sweden)

    Nilima Patnaik

    2012-08-01

    Full Text Available The objectives of the study are to analyze the physiological changes, biochemical alterations and attenuation of nickel toxicity effects in wheat seedlings under combined applications of Ni ions, metal chelators (EDTA/Citric Acid and metal ions (Zn2+ /Mg2+. Wheat (Triticum aestivum L cv UP262 seedlings were grown hydroponically using different concentrations of Ni up to 7 days along with chelators and metal ions for study. The seedling growth was maximum with NiCl2–Zn2+ (100μM and minimum with NiCl2–EDTA (100μM treatments. Total chlorophyll content was maximum in the seedlings treated with NiCl2-Zn2+ (100μM and minimum in NiCl2-EDTA (100μM treatments. NiCl2–EDTA (100μM showed less Fo and Fm values and therefore, a trend in the decrease in OJIP transient indicates the maximum alteration of photochemical activity of PS-II in presence of NiCl2–EDTA (100μM treatment. Similar observation was found by NiCl2 –EDTA (200μM treatment where Fo and Fm values were noted to decline. High nickel content in roots of the seedlings was noted as compared to shoots.

  8. Paramagnetic relaxation enhancement of membrane proteins by incorporation of the metal-chelating unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl)propanoic acid (HQA)

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang Ho; Wang, Vivian S.; Radoicic, Jasmina; Angelis, Anna A. De; Berkamp, Sabrina; Opella, Stanley J., E-mail: sopella@ucsd.edu [University of California, San Diego, Department of Chemistry and Biochemistry (United States)

    2015-04-15

    The use of paramagnetic constraints in protein NMR is an active area of research because of the benefits of long-range distance measurements (>10 Å). One of the main issues in successful execution is the incorporation of a paramagnetic metal ion into diamagnetic proteins. The most common metal ion tags are relatively long aliphatic chains attached to the side chain of a selected cysteine residue with a chelating group at the end where it can undergo substantial internal motions, decreasing the accuracy of the method. An attractive alternative approach is to incorporate an unnatural amino acid that binds metal ions at a specific site on the protein using the methods of molecular biology. Here we describe the successful incorporation of the unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl)propanoic acid (HQA) into two different membrane proteins by heterologous expression in E. coli. Fluorescence and NMR experiments demonstrate complete replacement of the natural amino acid with HQA and stable metal chelation by the mutated proteins. Evidence of site-specific intra- and inter-molecular PREs by NMR in micelle solutions sets the stage for the use of HQA incorporation in solid-state NMR structure determinations of membrane proteins in phospholipid bilayers.

  9. Production of chelating agents by Pseudomonas aeruginosa grown in the presence of thorium and uranium

    International Nuclear Information System (INIS)

    Premuzic, E.T.; Lin, M.; Francis, A.J.; Schubert, J.

    1986-01-01

    Chelating agents produced by microorganisms enhance the dissolution of iron increasing the mobility and bioavailability of the metal. Since some similarities exist in the biological behavior of ferric, thorium and uranyl ions, microorganisms resistant to these metals and which grow in their presence may produce sequestering agents of Th and U, and other metals in a manner similar to the complexation of iron by siderophores. The ability of P. aeruginosa to elaborate sequestering agents in medium containing thorium or uranium salts was tested. Uranium has a stronger inhibitory effect on growth of the organism than thorium at similar concentrations. Analyses of the culture media have shown, that relative to the control, and under the experimental conditions used, the microorganisms have produced several new chelating agents for thorium and uranium. Extracts containing these chelating agents have been tested for their decorporation potential. In vitro mouse liver bioassay and in vivo mouse toxicity tests indicate that their efficiency is comparable to DTPA and DFOA and that they are virtually non-toxic to mice. The bacterially produced compounds resemble, but are not identical to the known iron chelating siderophores isolated from microorganisms. Some of their chemical properties are also discussed. (author)

  10. Adsorption performances and mechanisms of the newly synthesized N,N'-di (carboxymethyl) dithiocarbamate chelating resin toward divalent heavy metal ions from aqueous media

    International Nuclear Information System (INIS)

    Jing Xiaosheng; Liu Fuqiang; Yang Xin; Ling Panpan; Li Lanjuan; Long Chao; Li Aimin

    2009-01-01

    N,N'-di (carboxymethyl) dithiocarbamate chelating resin (PSDC) was synthesized by anchoring the chelating agent of N,N'-di (carboxymethyl) dithiocarbamate to the chloromethylated PS-DVB (Cl-PS-DVB) matrix, as a new adsorbent for removing divalent heavy metal ions from waste-stream. The physicochemical structures of Cl-PS-DVB and PSDC were elaborately characterized using Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), and were further morphologically characterized using BET and BJH methods. The adsorption performances of PSDC towards heavy metals such as Cu(II), Pb(II) and Ni(II) were systematically investigated, based upon which the adsorption mechanisms were deeply exploited. For the above target, the classic batch adsorption experiments were conducted to explore the kinetics and isotherms of the removal processes with pH-value, initial concentration, temperature, and contact time as the controlling parameters. The kinetic and isotherm data could be well elucidated with Lagergren-second-order equation and Langmuir model respectively. The strong affinity of PSDC toward these target soft acids could be well demonstrated with the electrostatic attraction and chelating interaction caused by IDA moiety and sulphur which were namely soft bases on the concept of hard and soft acids and bases (HASB). Thermodynamic parameters, involving ΔH o , ΔS o and ΔG o were also calculated from graphical interpretation of the experimental data. The standard heats of adsorption (ΔH o ) were found to be endothermic and the entropy change values (ΔS o ) were calculated to be positive for the adsorption of Cu(II), Pb(II) and Ni(II) ions onto the tested adsorbents. Negative values of ΔG o indicated that adsorption processes for all tested metal ions onto PSDC were spontaneous.

  11. Preparation of surface imprinted core-shell particles via a metal chelating strategy: specific recognition of porcine serum albumin

    International Nuclear Information System (INIS)

    Li, Qinran; Li, Senwu; Liu, Lukuan; Yang, Kaiguang; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

    2016-01-01

    We describe the synthesis of molecularly imprinted core-shell microparticles via a metal chelating strategy that assists in the creation of selective recognition sites for albumin. Porcine serum albumin (PSA) was immobilized on silica beads via copper(II) chelation interaction. A solution containing 2-hydroxyethyl methacrylate and methacrylic acid as the monomers was mixed with the above particles, and free radical polymerization was performed at 25 °C. Copper ion and template were then removed to obtain PSA-imprinted core-shell particles (MIPs) with a typical diameter of 5 μm. The binding capacity of such MIP was 8.9 mg protein per gram of MIPs, and the adsorption equilibrium was established within <20 min. The imprinting factor for PSA reached 2.6 when the binding capacity was 7.7 mg protein per gram of MIPs. The use of such MIPs enabled PSA to be selectively recognized even in presence of the competitive proteins ribonuclease B, cytochrome c, and myoglobin. The results indicate that this imprinting strategy for protein may become a promising method to prepare MIPs for protein recognition. (author)

  12. Synthesis, Characterization and Chelating Properties of 4-Butyrylsemicarbazone-1-phenyl-3-methyl-2-pyrazolin-5-one

    Directory of Open Access Journals (Sweden)

    J. D. Patel

    2010-01-01

    Full Text Available 4-Butyrylsemicarbazone-1-phenyl-3-methyl-2-pyrazolin-5-one (BUMP-SC was prepared and its metal chelates of Cu2+, Ni2+, Co2+, Mn2+, Fe2+, Fe3+, Cr3+, UO2 and OV were prepared. The ligands and its chelates were characterized by elemental analysis, metal:ligand (M:L stoichiometry, IR-electronic spectral studies and magnetic properties. The compounds also were screened for their antimicrobial activity.

  13. Hypoglossal-facial anastomosis (HFA) over a 10 mm gap bridged by a Y-tube-conduit enhances neurite regrowth and reduces collateral axonal branching at the lesion site.

    Science.gov (United States)

    Ozsoy, Umut; Demirel, Bahadir Murat; Hizay, Arzu; Ozsoy, Ozlem; Ankerne, Janina; Angelova, Srebrina; Sarikcioglu, Levent; Ucar, Yasar; Angelov, Doychin N

    2011-01-01

    The outcome of severe peripheral nerve injuries requiring surgical repair (transection and suture) is usually poor. Recent work suggests that direct suture of nerves increases collagen production and provides unfavourable conditions for a proper axonal regrowth. We tested whether entubulation of the hypoglossal nerve into a Y-tube conduit connecting it with the zygomatic and buccal facial nerve branches would improve axonal pathfinding at the lesion site, quality of muscle reinnervation and recovery of vibrissal whisking. For hypoglossal-facial anastomosis (HFA) over a Y-tube (HFA-Y-tube) the proximal stump of the hypoglossal nerve was entubulated and sutured into the long arm of a Y-tube (isogeneic abdominal aorta with its bifurcation). The zygomatic and buccal facial branches were entubulated and sutured to the short arms of the Y-tube. Restoration of vibrissal motor performance, degree of collateral axonal branching at the lesion site and quality of neuro-muscular junction (NMJ) reinnervation were compared to animals receiving HFA-Coaptation (no entubulation) after 4 months. HFA-Y-tube reduced collateral axonal branching. However it failed to reduce the proportion of polyinnervated NMJ and did not improve functional outcome when compared to HFA-Coaptation. Elimination of compression by tightly opposed nerve fragments improved axonal pathfinding. However, biometric analysis of vibrissae movements did not show positive effects suggesting that polyneuronal reinnervation - rather than collateral branching - may be the critical limiting factor. Since polyinnervation of muscle fibers is activity-dependent and can be manipulated, the present findings raise hopes that clinically feasible and effective therapies after HFA could be soon designed and tested.

  14. The intra-annular acylamide chelate-coordinated compound: The keto-tautomer of metal (II) milrinone complex

    Science.gov (United States)

    Gong, Yun; Liu, Jinzhi; Tang, Wang; Hu, Changwen

    2008-03-01

    In the presence of N, N'-dimethyllformamide (DMF), two isostructural metal (II)-milrinone complexes formulated as M(C 12H 8N 3O) 2 (M = Co 1 and Ni 2) have been synthesized and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. The two compounds crystallize in the tetragonal system, chiral space group P4 32 12. They exhibit similar two dimensional (2D) square grid-like framework, in which milrinone acts as a ditopic ligand with its terminal pyridine and intra-annular acylamide groups covalently bridging different metal centers. The intra-annular acylamide ligand shows a chelate-coordinated mode. Compounds 1 and 2 are stable under 200 °C. Compound 3 formulated as (C 12H 9N 3O) 4·H 2O was obtained in the presence of water, the water molecule in the structure leads to the racemization of compound 3 and it crystallizes in the monoclinic system, non-chiral space group P2 1/ c. Milrinone exhibits a keto-form in the three compounds and compounds 1- 3 exhibit different photoluminescence properties.

  15. Comparative study of antioxidant, metal chelating and antiglycation activities of Momordica charantia flesh and pulp fractions.

    Science.gov (United States)

    Ghous, Tahseen; Aziz, Nouman; Mehmood, Zahid; Andleeb, Saiqa

    2015-07-01

    Momordica charantia is commonly used as a vegetable and folk medicine in most parts of South Asia. This study aims to determine and compare the antioxidant, metal chelating and antiglycation activities of aqueous extracts of M. charantia fruit flesh (MCF) and fruit pulp (MCP) fractions. Our results show that MCP has pronounced DPPH and ABTS radical scavenging potential compared to MCF. In the antiglycation assay both fractions illustrated considerable inhibitory activities against the formation of AGEs induced by glucose with an efficacy of 75 and 67% with 150 μl of MCP and MCF extracts respectively, almost equal to 0.3mM amino guanidine. Results for metal catalysed protein fragmentation and autoxidative and glycoxidation assays demonstrate that MCF and MCP inhibited metal catalysed protein fragmentation. The percentage of relative standard deviation for three replicate measurements of 150 μl of MCF and MCP was < 3.0% for antiglycation. The antioxidant assays with regression values of MCP (0.981 and 0.991) and MCF (0.967 and 0.999) were also recorded. We conclude that both extracts possess high antioxidant and antiglycation activities and are equally good sources of antioxidant and antiglycating agents.

  16. Impact of metal binding on the antitumor activity and cellular imaging of a metal chelator cationic imidazopyridine derivative.

    Science.gov (United States)

    Roy, Mithun; Chakravarthi, Balabhadrapatruni V S K; Jayabaskaran, Chelliah; Karande, Anjali A; Chakravarty, Akhil R

    2011-05-14

    A new water soluble cationic imidazopyridine species, viz. (1E)-1-((pyridin-2-yl)methyleneamino)-3-(3-(pyridin-2-yl)imidazo[1,5-a]pyridin-2(3H)-yl)propan-2-ol (1), as a metal chelator is prepared as its PF(6) salt and characterized. Compound 1 shows fluorescence at 438 nm on excitation at 342 nm in Tris-HCl buffer giving a fluorescence quantum yield (φ) of 0.105 and a life-time of 5.4 ns. Compound 1, as an avid DNA minor groove binder, shows pUC19 DNA cleavage activity in UV-A light of 365 nm forming singlet oxygen species in a type-II pathway. The photonuclease potential of 1 gets enhanced in the presence of Fe(2+), Cu(2+) or Zn(2+). Compound 1 itself displays anticancer activity in HeLa, HepG2 and Jurkat cells with an enhancement on addition of the metal ions. Photodynamic effect of 1 at 365 nm also gets enhanced in the presence of Fe(2+) and Zn(2+). Fluorescence-based cell cycle analysis shows a significant dead cell population in the sub-G1 phase of the cell cycle suggesting apoptosis via ROS generation. A significant change in the nuclear morphology is observed from Hoechst 33258 and an acridine orange/ethidium bromide (AO/EB) dual nuclear staining suggesting apoptosis in cells when treated with 1 alone or in the presence of the metal ions. Apoptosis is found to be caspase-dependent. Fluorescence imaging to monitor the distribution of 1 in cells shows that 1 in the presence of metal ions accumulates predominantly in the cytoplasm. Enhanced uptake of 1 into the cells within 12 h is observed in the presence of Fe(2+) and Zn(2+).

  17. STUDIES REGARDING THE CHELATE-INDUCED HYPERACCUMULATION OF CU AND FE USING LOLIUM PERENNE SPECIES IN MINING AREAS

    Directory of Open Access Journals (Sweden)

    ANCA-DIANA PRICOP

    2009-05-01

    Full Text Available The plant capacity to absorb high amounts of metal for a short period of time is the major factor that influences the efficiency of phytoextraction. The hyperaccumulating plants uptake high amounts in their tissues correlated to the metal concentrations in soil. Chelating agents have the capacity to induce the metal accumulation in biomass. They increase metal bioavailability for plants by releasing the metal in accessible forms. The present study emphasizes that in the case of EDTA use, the obtained biomass is smaller compared to the other variants, showing a lower tolerance to this chelating agent of Lolium perenne species. Cu and Fe phytoextraction by Lolium perenne species is higher in the case of EDTA use. Cu bioaccumulation has higher values in variants with compost-sterile mixture ratio of 1:4 in comparison with Fe. In the case of the best compost-sterile mixture ratio of 1:3 the highest biomass is obtained in all the variants, biosolids’ effect being stronger compared to the chelating agent.

  18. Rates of nickel(II) capture from complexes with NTA, EDDA, and related tetradentate chelating agents by the hexadentate chelating agents EDTA and CDTA: Evidence of a "semijunctive" ligand exchange pathway

    Science.gov (United States)

    Boland, Nathan E.; Stone, Alan T.

    2017-09-01

    Many siderophores and metallophores produced by soil organisms, as well as anthropogenic chelating agent soil amendments, rely upon amine and carboxylate Lewis base groups for metal ion binding. UV-visible spectra of metal ion-chelating agent complexes are often similar and, as a consequence, whole-sample absorbance measurements are an unreliable means of monitoring the progress of exchange reactions. In the present work, we employ capillary electrophoresis to physically separate Ni(II)-tetradentate chelating agent complexes (NiL) from Ni(II)-hexadentate chelating agent complexes (NiY) prior to UV detection, such that progress of the reaction NiL + Y → NiY + L can be conveniently monitored. Rates of ligand exchange for Ni(II) are lower than for other +II transition metal ions. Ni(II) speciation in environmental media is often under kinetic rather than equilibrium control. Nitrilotriacetic acid (NTA), with three carboxylate groups all tethered to a central amine Lewis base group, ethylenediamine-N,N‧-diacetic acid (EDDA), with carboxylate-amine-amine-carboxylate groups arranged linearly, plus four structurally related compounds, are used as tetradentate chelating agents. Ethylenediaminetetraacetic acid (EDTA) and the structurally more rigid analog trans-cyclohexaneethylenediaminetetraacetic acid (CDTA) are used as hexadentate chelating agents. Effects of pH and reactant concentration are explored. Ni(II) capture by EDTA was consistently more than an order of magnitude faster than capture by CDTA, and too fast to quantify using our capillary electrophoresis-based technique. Using NiNTA as a reactant, Ni(II) capture by CDTA is independent of CDTA concentration and greatly enhanced by a proton-catalyzed pathway at low pH. Using NiEDDA as reactant, Ni(II) capture by CDTA is first order with respect to CDTA concentration, and the contribution from the proton-catalyzed pathway diminished by CDTA protonation. While the convention is to assign either a disjunctive

  19. Preparation of novel polyamine-type chelating resin with hyperbranched structures and its adsorption performance

    Science.gov (United States)

    Zhao, Wei; Wang, Huan; Li, Yuhong; Li, Chenxi

    2018-01-01

    This paper explored the method of combining atom transfer radical polymerization (ATRP) technology and hyperbranched polymer principle to prepare the high capacity chelating resin. First, surface-initiated atom transfer radical polymerization (SI-ATRP) method was used to graft glycidyl methacrylate (GMA) on chloromethylated cross-linked styrene-divinylbenzene resin, and then the novel polyamine chelating resin with a kind of hyperbranched structure was prepared through the amination reaction between amino group of (2-aminoethyl) triamine and epoxy group in GMA. This resin had a selective effect on As(V) and Cr(VI) at a relatively low pH and can be used for the disposal of waste water containing As(V) and Cr(VI). It had a relatively strong adsorption effect on Cu(II), Pb(II), Cd(II) and Cr(III) and can be used for the disposal of heavy metal ion waste water. The finding was that, the adsorption capacity of resin on the studied heavy metal ions was higher than that of the chelating resin synthesized by traditional technology and also higher than that of the resin modified by ATRP technology and bifunctional chelator, indicating that the combination of ATRP and hyperbranched polymer concept is an effective method to prepare chelating resin with high capacity. PMID:29515875

  20. Preparation of novel polyamine-type chelating resin with hyperbranched structures and its adsorption performance

    Science.gov (United States)

    Chen, Youning; Zhao, Wei; Wang, Huan; Li, Yuhong; Li, Chenxi

    2018-02-01

    This paper explored the method of combining atom transfer radical polymerization (ATRP) technology and hyperbranched polymer principle to prepare the high capacity chelating resin. First, surface-initiated atom transfer radical polymerization (SI-ATRP) method was used to graft glycidyl methacrylate (GMA) on chloromethylated cross-linked styrene-divinylbenzene resin, and then the novel polyamine chelating resin with a kind of hyperbranched structure was prepared through the amination reaction between amino group of (2-aminoethyl) triamine and epoxy group in GMA. This resin had a selective effect on As(V) and Cr(VI) at a relatively low pH and can be used for the disposal of waste water containing As(V) and Cr(VI). It had a relatively strong adsorption effect on Cu(II), Pb(II), Cd(II) and Cr(III) and can be used for the disposal of heavy metal ion waste water. The finding was that, the adsorption capacity of resin on the studied heavy metal ions was higher than that of the chelating resin synthesized by traditional technology and also higher than that of the resin modified by ATRP technology and bifunctional chelator, indicating that the combination of ATRP and hyperbranched polymer concept is an effective method to prepare chelating resin with high capacity.

  1. In vitro and in vivo evaluation of potential aluminum chelators.

    Science.gov (United States)

    Graff, L; Muller, G; Burnel, D

    1995-10-01

    The potential for aluminium (Al) chelation by different compounds was determined using 2 in vitro techniques. The formation of stable complexes with Al in an aqueous solution was evaluated using pulse polarography. This technique allowed the influence of temperature and calcium (Ca) to be studied for each compound. Certain compounds (EDDHA, HAES, citric acid and HBED) showed great chelation in the absence of Ca2+ at a temperature of 37 +/- 1 C. An ultrafiltration technique combined with Al determination by atomic emission spectroscopy allowed the efficiency of different substances to complex Al that were previously bound to serum proteins to be estimated. The kinetics of chelation and minimum efficient concentration have been determined for all products studied. EDDHA had chelation potential similar to DFO. The real efficacies of the compounds were studied in vivo to compare the effectiveness of repeated administrations of the best chelating agents (EDDHA, DFO, HAES and tartaric acid) on the distribution and excretion of Al after repeated i.p. administrations to rats. Intraperitoneal EDDHA significantly increased urinary metal (Al, Ca, Cu, Fe and Zn) excretion. These excretions may be correlated to a renal toxic potential property.

  2. Zn availability in nutrient solutions for cucumber (Cucumis sativus L) in hydroponics as affected by Fe-chelates and pH

    NARCIS (Netherlands)

    Voogt, W.; Sonneveld, C.

    2017-01-01

    In soil-less culture systems Fe is usually supplied as chelate to ensure an adequate availability of this element. As chelates have affinity for many metal ions these chelates will interact with other cation nutrients in nutrient solutions. This affects the availability of Fe and other nutrients.

  3. Molecular structure and conformation of two acyclic polythioethers: Implications for the design of heavy metal chelators

    Energy Technology Data Exchange (ETDEWEB)

    Desper, J.M.; Powell, D.R.; Gellman, S.H. (Univ. of Wisconsin, Madison (USA))

    1990-05-23

    The crystal structures of the 1,9-bis(p-tolyl)-2,5,8-trithianonane (1) and 1,12-bis(p-tolyl)-2,5,8,11-tetrathiadodecane (2) are reported. Previous studies of macrocyclic polythioethers have revealed a pronounced tendency for backbone CS-CC bonds to adopt gauche torsion angles. The same tendency is observed in the homologous acyclic polythioethers 1 and 2, demonstrating that the gauche preference is not simply the result of a macrocyclic constraint. Because of this gauche preference of CS-CC torsion units and the well-established anti preference of SC-CS torsion units, polythioethers constructed from ethylene sulfide subunits are generally far from preorganized for metal ion chelation.

  4. Water-soluble chelating polymers for removal of actinides from wastewater

    International Nuclear Information System (INIS)

    Jarvinen, G.D.

    1997-01-01

    Polymer filtration is a technology under development to selectively recover valuable or regulated metal ions from process or wastewaters. The technology uses water-soluble chelating polymers that are designed to selectively bind with metal ions in aqueous solutions. The polymers have a sufficiently large molecular weight that they can be separated and concentrated using available ultrafiltration (UF) technology. The UF range is generally considered to include molecular weights from about 3000 to several million daltons and particles sizes of about 2 to 1000 nm. Water and smaller unbound components of the solution pass freely through the UF membrane. The polymers can then be reused by changing the solution conditions to release the metal ions that are recovered in concentrated form for recycle or disposal. Some of the advantages of polymer filtration relative to technology now in use are rapid binding kinetics, high selectivity, low energy and capital costs, and a small equipment footprint. Some potential commercial applications include electroplating rinse waters, photographic processing, nuclear power plant cooling water; remediation of contaminated soils and groundwater; removal of mercury contamination; and textile, paint and dye production. The purpose of this project is to evaluate this technology to remove plutonium, americium, and other regulated metal ions from various process and waste streams found in nuclear facilities. The work involves preparation of the water-soluble chelating polymers; small-scale testing of the chelating polymer systems for the required solubility, UF properties, selectivity and binding constants; followed by an engineering assessment at a larger scale to allow comparison to competing separation technologies. This project focuses on metal-ion contaminants in waste streams at the Plutonium Facility and the Waste Treatment Facility at LANL. Potential applications at other DOE facilities are also apparent

  5. Water-soluble chelating polymers for removal of actinides from wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Jarvinen, G.D. [Los Alamos National Lab., NM (United States)

    1997-10-01

    Polymer filtration is a technology under development to selectively recover valuable or regulated metal ions from process or wastewaters. The technology uses water-soluble chelating polymers that are designed to selectively bind with metal ions in aqueous solutions. The polymers have a sufficiently large molecular weight that they can be separated and concentrated using available ultrafiltration (UF) technology. The UF range is generally considered to include molecular weights from about 3000 to several million daltons and particles sizes of about 2 to 1000 nm. Water and smaller unbound components of the solution pass freely through the UF membrane. The polymers can then be reused by changing the solution conditions to release the metal ions that are recovered in concentrated form for recycle or disposal. Some of the advantages of polymer filtration relative to technology now in use are rapid binding kinetics, high selectivity, low energy and capital costs, and a small equipment footprint. Some potential commercial applications include electroplating rinse waters, photographic processing, nuclear power plant cooling water; remediation of contaminated soils and groundwater; removal of mercury contamination; and textile, paint and dye production. The purpose of this project is to evaluate this technology to remove plutonium, americium, and other regulated metal ions from various process and waste streams found in nuclear facilities. The work involves preparation of the water-soluble chelating polymers; small-scale testing of the chelating polymer systems for the required solubility, UF properties, selectivity and binding constants; followed by an engineering assessment at a larger scale to allow comparison to competing separation technologies. This project focuses on metal-ion contaminants in waste streams at the Plutonium Facility and the Waste Treatment Facility at LANL. Potential applications at other DOE facilities are also apparent.

  6. Emission properties of Sm(III) complex having ten-coordination structure

    International Nuclear Information System (INIS)

    Hasegawa, Yasuchika; Tsuruoka, Shin-ichi; Yoshida, Takahiko; Kawai, Hideki; Kawai, Tsuyoshi

    2008-01-01

    Sammarium(III) complex having ten-coordination structure, bis-(1,10-phenanthroline)tris-(hexafluoroacetylacetonato)samarium(III) (Sm(hfa) 3 (phen) 2 ) was prepared by chelation of tris-(hexafluoroacetylacetonato) samarium(III) (Sm(hfa) 3 (H 2 O) 2 ) with 1,10-phenantroline (phen). The characteristic ten-coordination structure of Sm(hfa) 3 (phen) 2 was determined by 1 H NMR and elemental analyses. Strong deep-red emission (λ max =643 nm) and narrow emission band (FWHM=5 nm) of Sm(hfa) 3 (phen) 2 originated from electronic allowed transition from characteristics ten coordinate structure. The emission quantum yields Sm(hfa) 3 (phen) 2 excited at absorption bands of ligands and Sm(III) ion were found to be 0.36 and 1.4%, respectively

  7. Investigation on the influence of metal ion impurities on the complexation behavior of generator produced {sup 90}Y with bifunctional chelators

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Usha; Gamre, Naresh; Dash, Ashutosh [Isotope Applications and Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai (India)

    2014-05-01

    The {sup 90}Sr/ {sup 90}Y generator is the exclusive source of 'no carrier added' {sup 90}Y for targeted therapy. However, the concomitant presence of trace metals diminishes the complexation of {sup 90}Y with bifunctional chelators (BFCs). A systematic investigation was performed to evaluate the influence of trace metals on the complexation of {sup 90}Y (from an electrochemical generator) with BFCs such as p-SCN-Bn-PCTA, p-SCN-Bn-DTPA and p-SCN-Bn-DOTA. Our study indicates that while p-SCN-Bn-DTPA was least affected by most of the trace metals studied, p-SCN-Bn-PCTA was most sensitive to their presence and hence could be the ligand of choice for assessing the chemical purity of generator derived {sup 90}Y. (author)

  8. In vitro growth inhibition of mastitis causing bacteria by phenolics and metal chelators

    Energy Technology Data Exchange (ETDEWEB)

    Chew, B.P.; Tjoelker, L.W.; Tanaka, T.S.

    1985-11-01

    Antimicrobial activities of three phenolic compounds and four metal chelators were tested at 0, 250, 500, and 1000 ppm in vitro against four major mastitis-causing bacteria, Streptococcus agalactiae, Staphylococcus aureus, Klebsiella pnuemoniae, and Escherichia coli. Overall, butylated hydroxyanisole and tert-butylhydroquinone showed the greatest antimicrobial activity. These phenolics were bactericidal at 250 to 500 ppm against all four bacteria tested. The butylated hydroxytoluene was bactericidal against the gram-positive bacteria but was ineffective against the coliforms. At 250 ppm, disodium ethylenediaminetetraacetic acid was bactericidal against the gram-positive bacteria but much less effective against the gram-negatives. However, diethylene-triaminepentaacetic acid was more growth inhibitory than ethylenediaminetetraacetic acid against the gram-negative bacteria and especially against Escherichia coli. All other compounds were generally much less effective or ineffective against all four microorganisms. Therefore, butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid may have practical implications in the prevention or treatment of bovine mastitis.

  9. Monitoring the effects of chelating agents and electrical fields on active forms of Pb and Zn in contaminated soil.

    Science.gov (United States)

    Tahmasbian, Iman; Safari Sinegani, Ali Akbar

    2013-11-01

    The application of electrical fields and chelating agents is an innovative hybrid technology used for the decontamination of soil polluted by heavy metals. The effects of four center-oriented electrical fields and chelating agents on active fractions of lead and zinc were investigated in this pot experiment. Ethylenediaminetetraacetic acid (EDTA) as a synthetic chelator and cow manure extract (CME) and poultry manure extract (PME) as natural chelators were applied to the pots (2 g kg(-1)) 30 days after the first irrigation. Two weeks later, four center-oriented electrical fields were applied in each pot (in three levels of 0, 10, and 30 V) for 1 h each day for 14 days. The soil near the cathode and anodes was collected and analyzed as cathodic and anodic soil, respectively. Results indicated that the soluble-exchangeable fraction of lead and zinc were decreased in the cathodic soil, while the carbonate-bound fractions were increased. In the anodic soil, however, the opposite result was observed. EDTA enhanced the soluble-exchangeable form of the metals in both anodic and cathodic soils. Furthermore, the amounts of carbonate-bound heavy metals were increased by the application of CME in both soils. The organic-bound fraction of the metals was increased by the application of natural chelators, while electrical fields had no significant impacts on this fraction.

  10. Albumin microspheres labeled with Ga-67 by chelation: concise communication

    International Nuclear Information System (INIS)

    Hnatowich, D.J.; Schlegel, P.

    1981-01-01

    Albumin microspheres have been synthesized with EDTA and DTPA chelating groups covalently bound to their surface. The microspheres may be labeled with Ga-67 at high yield (97 +- 2%) by transcomplexation from a 0.1 M Ga-67 acetate solution. With EDTA microspheres the resulting label dissociates only slightly after 24 hr in 50% plasma at 37 0 C, whereas with DTPA microspheres the label shows no detectable dissociation over this period. By contrast, microspheres without chelating groups lose their label virtually completely under these conditions. Following intravenous administration of sized Ga-67 DTPA microspheres in mice, about (84 +- 16)% of the activity localizes in the lungs at 5 min, with (60 +- 7)% remaining after 2 h. Since labeling is by chelation, the microspheres may also be tagged with other metallic radionuclides

  11. N- vs. C-Domain Selectivity of Catalytic Inactivation of Human Angiotensin Converting Enzyme by Lisinopril-Coupled Transition Metal Chelates

    Science.gov (United States)

    Hocharoen, Lalintip; Joyner, Jeff C.; Cowan, J. A.

    2014-01-01

    The N- and C-terminal domains of human somatic Angiotensin I Converting Enzyme (sACE-1) demonstrate distinct physiological functions, with resulting interest in the development of domain-selective inhibitors for specific therapeutic applications. Herein, the activity of lisinopril-coupled transition metal chelates were tested for both reversible binding and irreversible catalytic inactivation of sACE-1. C/N domain binding selectivity ratios ranged from 1 to 350, while rates of irreversible catalytic inactivation of the N- and C-domains were found to be significantly greater for the N-domain, suggesting a more optimal orientation of the M-chelate-lisinopril complexes within the active site of the N-domain of sACE-1. Finally, the combined effect of binding selectivity and inactivation selectivity was assessed for each catalyst (double-filter selectivity factors), and several catalysts were found to cause domain-selective catalytic inactivation. The results of this study demonstrate the ability to optimize the target selectivity of catalytic metallopeptides through both binding and orientation factors (double-filter effect). PMID:24228790

  12. N- versus C-domain selectivity of catalytic inactivation of human angiotensin converting enzyme by lisinopril-coupled transition metal chelates.

    Science.gov (United States)

    Hocharoen, Lalintip; Joyner, Jeff C; Cowan, J A

    2013-12-27

    The N- and C-terminal domains of human somatic angiotensin I converting enzyme (sACE-1) demonstrate distinct physiological functions, with resulting interest in the development of domain-selective inhibitors for specific therapeutic applications. Herein, the activity of lisinopril-coupled transition metal chelates was tested for both reversible binding and irreversible catalytic inactivation of each domain of sACE-1. C/N domain binding selectivity ratios ranged from 1 to 350, while rates of irreversible catalytic inactivation of the N- and C-domains were found to be significantly greater for the N-domain, suggesting a more optimal orientation of M-chelate-lisinopril complexes within the active site of the N-domain of sACE-1. Finally, the combined effect of binding selectivity and inactivation selectivity was assessed for each catalyst (double-filter selectivity factors), and several catalysts were found to cause domain-selective catalytic inactivation. The results of this study demonstrate the ability to optimize the target selectivity of catalytic metallopeptides through both binding and catalytic factors (double-filter effect).

  13. Effect of electrostatic charge in plastic spacers on the lung delivery of HFA-salbutamol in children

    DEFF Research Database (Denmark)

    Anhøj, J; Bisgaard, H; Lipworth, B J

    1999-01-01

    was delivered on 3 different study days from plastic spacers with mouthpiece. Pre-treatment of the spacers differed between study days: (a) Non-electrostatic 350 ml Babyhaler (coated with benzalkonium chloride) (b) New 350 ml Babyhaler (rinsed in water), and (c) New 145 ml AeroChamber (rinsed in water). Plasma......AIMS: The effect of the electrostatic charge in plastic spacers in vivo on drug delivery to the lung of hydrofluoroalkane (HFA) salbutamol spray was studied in children. METHODS: Five children, aged 7-12 years, were included in a 3-way crossover randomised single-blind trial. Salbutamol HFA spray...... salbutamol was measured before and 5, 10, 15 and 20 min after inhalation of four single puffs of 100 microg salbutamol. Cmax and Cav (5-20min) were calculated as a reflection of lung dose. RESULTS: For Cmax: (A) Non-electrostatic Babyhaler 4.3 ng ml(-1) (B) New Babyhaler 1.9 ng ml(-1) (C) New AeroChamber 1...

  14. Biosorption of heavy metals by a marine bacterium

    Energy Technology Data Exchange (ETDEWEB)

    Iyer, Anita [Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat (India); Mody, Kalpana [Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat (India)]. E-mail: khmody@csmcri.org; Jha, Bhavanath [Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat (India)

    2005-03-01

    Heavy metal chelation property of exopolysaccharide produced by Enterobacter cloaceae, a marine bacterium, isolated from the West Coast of India, is reported in this paper. The exopolysaccharide demonstrated excellent chelating properties with respect to cadmium (65%) followed by copper (20%) and cobalt (8%) at 100 mg/l heavy metal concentration. However, it could not chelate mercury. A comparative study of the percentage biosorption of the above mentioned metals is presented here.

  15. Biosorption of heavy metals by a marine bacterium

    International Nuclear Information System (INIS)

    Iyer, Anita; Mody, Kalpana; Jha, Bhavanath

    2005-01-01

    Heavy metal chelation property of exopolysaccharide produced by Enterobacter cloaceae, a marine bacterium, isolated from the West Coast of India, is reported in this paper. The exopolysaccharide demonstrated excellent chelating properties with respect to cadmium (65%) followed by copper (20%) and cobalt (8%) at 100 mg/l heavy metal concentration. However, it could not chelate mercury. A comparative study of the percentage biosorption of the above mentioned metals is presented here

  16. Removal of PCR error products and unincorporated primers by metal-chelate affinity chromatography.

    Directory of Open Access Journals (Sweden)

    Indhu Kanakaraj

    Full Text Available Immobilized Metal Affinity Chromatography (IMAC has been used for decades to purify proteins on the basis of amino acid content, especially surface-exposed histidines and "histidine tags" genetically added to recombinant proteins. We and others have extended the use of IMAC to purification of nucleic acids via interactions with the nucleotide bases, especially purines, of single-stranded RNA and DNA. We also have demonstrated the purification of plasmid DNA from contaminating genomic DNA by IMAC capture of selectively-denatured genomic DNA. Here we describe an efficient method of purifying PCR products by specifically removing error products, excess primers, and unincorporated dNTPs from PCR product mixtures using flow-through metal-chelate affinity adsorption. By flowing a PCR product mixture through a Cu(2+-iminodiacetic acid (IDA agarose spin column, 94-99% of the dNTPs and nearly all the primers can be removed. Many of the error products commonly formed by Taq polymerase also are removed. Sequencing of the IMAC-processed PCR product gave base-calling accuracy comparable to that obtained with a commercial PCR product purification method. The results show that IMAC matrices (specifically Cu(2+-IDA agarose can be used for the purification of PCR products. Due to the generality of the base-specific mechanism of adsorption, IMAC matrices may also be used in the purification of oligonucleotides, cDNA, mRNA and micro RNAs.

  17. Renewable Modified Cellulose Bearing Chelating Schiff Base for Adsorptive Removal of Heavy Metal Ions and Antibacterial Action.

    Science.gov (United States)

    Saravanan, R; Ravikumar, L

    2017-07-01

      A novel approach toward chemically modified cellulose bearing active chelating Schiff base with hydroxyl group (Cell-Hy) was synthesized. The modified cellulose was examined for its heavy metal ion uptake potential from aqueous solution. The chemical and structural features of the adsorbent were characterized by Fourier transform infrared spectroscopy (FT-IR), solid state 13C-NMR, Scanning Electron Microscopy (SEM), and energy dispersive analysis of X-ray (EDAX) observations. The experimental conditions and adsorption parameters, including pH, initial metal ion concentration, adsorbent dosage, temperature, and contact time were optimized for the removal of Cu(II) and Pb(II) ions. Kinetic parameters, equilibrium adsorption capacities, and correlation coefficients for pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were carried out. The data obtained from the adsorption of Cu(II) and Pb(II) onto Cell-Hy were subjected to Langmuir and Freundlich isotherm models. Thermodynamic parameters have also been evaluated. The antibacterial activity of modified cellulose was tested toward specific bacterial species.

  18. Uranium and neodymium biosorption using novel chelating polysaccharide.

    Science.gov (United States)

    Elsalamouny, Ahmed R; Desouky, Osman A; Mohamed, Saad A; Galhoum, Ahmed A; Guibal, Eric

    2017-11-01

    A direct reaction is described to prepare hydrophobic α-aminomethylphosphonic acid as a novel chitosan-based material. It exhibits chelating properties for polyvalent metal ions such as U(VI) and Nd(III) ions. The new sorbent was fully characterized using Elemental analysis, scanning electron microscope (SEM) and FTIR spectra. Different parameters were examined in order to evaluate the optimum conditions for U(VI) and Nd(III) ions biosorption. Sorption mechanisms of metal ions were investigated using kinetic and isotherm models. In addition, the sorbent selectivity was tested for both metal ions together in a binary solution. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Repurposing of Copper(II)-chelating Drugs for the Treatment of Neurodegenerative Diseases.

    Science.gov (United States)

    Lanza, Valeria; Milardi, Danilo; Di Natale, Giuseppe; Pappalardo, Giuseppe

    2018-02-12

    There is mounting urgency to find new drugs for the treatment of neurodegenerative disorders. A large number of reviews have exhaustively described either the molecular or clinical aspects of neurodegenerative diseases such as Alzheimer's (AD) and Parkinson's (PD). Conversely, reports outlining how known drugs in use for other diseases can also be effective as therapeutic agents in neurodegenerative diseases are less reported. This review focuses on the current uses of some copper(II) chelating molecules as potential drug candidates in neurodegeneration. Starting from the well-known harmful relationships existing between the dyshomeostasis and mis-management of metals and AD onset, we surveyed the experimental work reported in the literature, which deals with the repositioning of metal-chelating drugs in the field of neurodegenerative diseases. The reviewed papers were retrieved from common literature and their selection was limited to those describing the biomolecular aspects associated with neuroprotection. In particular, we emphasized the copper(II) coordination abilities of the selected drugs. Copper, together with zinc and iron, are known to play a key role in regulating neuronal functions. Changes in copper homeostasis are crucial for several neurodegenerative disorders. The studies included in this review may provide an overview on the current strategies aimed at repurposing copper (II) chelating drugs for the treatment of neurodegenerative disorders. Starting from the exemplary case of clioquinol repurposing, we discuss the challenge and the opportunities that repurposing of other metal-chelating drugs may provide (e.g. PBT-2, metformin and cyclodipeptides) in the treatment of neurodegenerative disease. In order to improve the success rate of drug repositioning, comprehensive studies on the molecular mechanism and therapeutic efficacy are still required. The present review upholds that drug repurposing makes significant advantages over drug discovery since

  20. Metal chelates of phosphonate-containing ligands-III Analytical applications of N,N,N',N'-ethylenediaminetetra(methylenephosphonic) acid.

    Science.gov (United States)

    Zaki, M T; Rizkalla, E N

    1980-05-01

    N,N*,N',N'-Ethylenediaminetetra(methylenephosphonic) acid is used as a titrant for the direct determination of Cu, Co and Ni, with murexide as indicator. Indirect titrimetric procedures are suggested for the determination of silver, mercury, zinc and cyanide and both direct and indirect methods are applied for the analysis of binary mixtures of silver (or mercury) and copper (cobalt or nickel). The stoichiometry of the reaction, interferences of some metal ions and the pH effects on the complexation reactions are discussed. The values of the equilibrium constants of the protonated CuH(n)L (n = 1, 2, 3 and 4) as well as the unprotonated CuL chelates have been measured.

  1. Optimization of fuel cell membrane electrode assemblies for transition metal ion-chelating ordered mesoporous carbon cathode catalysts

    Directory of Open Access Journals (Sweden)

    Johanna K. Dombrovskis

    2014-12-01

    Full Text Available Transition metal ion-chelating ordered mesoporous carbon (TM-OMC materials were recently shown to be efficient polymer electrolyte membrane fuel cell (PEMFC catalysts. The structure and properties of these catalysts are largely different from conventional catalyst materials, thus rendering membrane electrode assembly (MEA preparation parameters developed for conventional catalysts not useful for applications of TM-OMC catalysts. This necessitates development of a methodology to incorporate TM-OMC catalysts in the MEA. Here, an efficient method for MEA preparation using TM-OMC catalyst materials for PEMFC is developed including effects of catalyst/ionomer loading and catalyst/ionomer-mixing and application procedures. An optimized protocol for MEA preparation using TM-OMC catalysts is described.

  2. A Sosh iPad Application Intervention: Social Skills and Students Diagnosed with High Functioning Autism (HFA)

    Science.gov (United States)

    Weeks, Nancy Anne

    2017-01-01

    The purpose of this quantitative study was to investigate the effect of a 4-week, school-based, Sosh iPad application intervention on the social skills inventory of participants diagnosed with High Functioning Autism (HFA). The intervention implementation took place during a 4-week period at two separate public school districts within the…

  3. Synthesis and physicochemical analysis of Sm (II, III) acetylacetone chelate complexes

    International Nuclear Information System (INIS)

    Kostyuk, N.N.; Dik, T.A.; Trebnikov, A.G.

    2004-01-01

    Sm (II, III) acetylacetone chelate complexes were synthesized by electrochemical method. It was shown that anode dissolution of the metal samarium over acetylacetone leads to formation of the Sm (II, III) chelate complexes: xSm(acac)2 · ySm(acac)3 · zH(acac). Factors x, y and z depend on quantity of the electricity, which flew through the electrolysis cell. The compositions of the obtained substances were confirmed by the physicochemical analysis (ultimate analysis, IR-, mass spectroscopy and thermal analysis (thermogravimetric, isothermal warming-up and differential scanning colorimetry). (Authors)

  4. A Systematic Review of Antiamyloidogenic and Metal-Chelating Peptoids: Two Structural Motifs for the Treatment of Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Sherri C. Young

    2018-01-01

    Full Text Available Alzheimer’s disease (AD is an incurable form of dementia affecting millions of people worldwide and costing billions of dollars in health care-related payments, making the discovery of a cure a top health, societal, and economic priority. Peptide-based drugs and immunotherapies targeting AD-associated beta-amyloid (Aβ aggregation have been extensively explored; however, their therapeutic potential is limited by unfavorable pharmacokinetic (PK properties. Peptoids (N-substituted glycine oligomers are a promising class of peptidomimetics with highly tunable secondary structures and enhanced stabilities and membrane permeabilities. In this review, the biological activities, structures, and physicochemical properties for several amyloid-targeting peptoids will be described. In addition, metal-chelating peptoids with the potential to treat AD will be discussed since there are connections between the dysregulation of certain metals and the amyloid pathway.

  5. AquaMUNE, a brown seaweed extract, improves metabolism, immune response, energy and chelates heavy metals.

    Science.gov (United States)

    1998-01-01

    The National Cancer Institute (NCI) has shown interest in the curative powers of ocean plants, many of which appear to possess powerful anti-inflammatory, antiviral, antimicrobial, antifungal, anticancer, and immuno-suppressive properties. AQUAMune, a brown seaweed extract developed by Aqua-10 Laboratories, has gained marketing rights for use as a nutritional supplement. Research shows that it acts as a receptor blocker for many pathogens, including Salmonella, and is effective against Haemophilus pneumonia. AQUAMune is also reported to inhibit outbreaks of genital herpes. Other marine plants are also showing positive curative powers. Evidence reveals that a red marine algae from the Philippines has selective antitumor properties; and that carageenans, a family of sulfated polysaccharides, appear to have anti-viral capabilities. Seaweeds act as natural chelators of heavy metals that improve metabolism in cells, increase ATP production, body temperature, energy levels, and immune function.

  6. Increased Uptake of Chelated Copper Ions by Lolium perenne Attributed to Amplified Membrane and Endodermal Damage

    Directory of Open Access Journals (Sweden)

    Anthea Johnson

    2015-10-01

    Full Text Available The contributions of mechanisms by which chelators influence metal translocation to plant shoot tissues are analyzed using a combination of numerical modelling and physical experiments. The model distinguishes between apoplastic and symplastic pathways of water and solute movement. It also includes the barrier effects of the endodermis and plasma membrane. Simulations are used to assess transport pathways for free and chelated metals, identifying mechanisms involved in chelate-enhanced phytoextraction. Hypothesized transport mechanisms and parameters specific to amendment treatments are estimated, with simulated results compared to experimental data. Parameter values for each amendment treatment are estimated based on literature and experimental values, and used for model calibration and simulation of amendment influences on solute transport pathways and mechanisms. Modeling indicates that chelation alters the pathways for Cu transport. For free ions, Cu transport to leaf tissue can be described using purely apoplastic or transcellular pathways. For strong chelators (ethylenediaminetetraacetic acid (EDTA and diethylenetriaminepentaacetic acid (DTPA, transport by the purely apoplastic pathway is insufficient to represent measured Cu transport to leaf tissue. Consistent with experimental observations, increased membrane permeability is required for simulating translocation in EDTA and DTPA treatments. Increasing the membrane permeability is key to enhancing phytoextraction efficiency.

  7. Characterization of antibody-chelator conjugates: Determination of chelator content by terbium fluorescence titration

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, K.D.; Schnobrich, K.E.; Johnson, D.K. (Abbott Laboratories, Department 90M, Abbott Park, IL (United States))

    1991-01-01

    Fluorescence titrations were performed by adding varying mole ratios of terbium(III) to antibody conjugates formed by benzyl isothiocyanate derivatives of three different polyaminopolycarboxylate chelators (NTA, EDTA, and DTPA) and the results compared to values for average chelator content obtained by cobalt-57 binding assays. For two different murine monoclonal antibodies, the average chelator content obtained by terbium fluorescence titration correlated closely with that measured by the cobalt-57 binding assay. It is concluded that lanthanide fluorescence titrations provide a useful alternative to radiometal binding assays for the determination of chelator content in protein-chelator conjugates.

  8. Characterization of antibody-chelator conjugates: Determination of chelator content by terbium fluorescence titration

    International Nuclear Information System (INIS)

    Brandt, K.D.; Schnobrich, K.E.; Johnson, D.K.

    1991-01-01

    Fluorescence titrations were performed by adding varying mole ratios of terbium(III) to antibody conjugates formed by benzyl isothiocyanate derivatives of three different polyaminopolycarboxylate chelators (NTA, EDTA, and DTPA) and the results compared to values for average chelator content obtained by cobalt-57 binding assays. For two different murine monoclonal antibodies, the average chelator content obtained by terbium fluorescence titration correlated closely with that measured by the cobalt-57 binding assay. It is concluded that lanthanide fluorescence titrations provide a useful alternative to radiometal binding assays for the determination of chelator content in protein-chelator conjugates

  9. Determination of residual fluoroquinolones in honey by liquid chromatography using metal chelate affinity chromatography.

    Science.gov (United States)

    Yatsukawa, Yoh-Ichi; Ito, Hironobu; Matsuda, Takahiro; Nakamura, Munetomo; Watai, Masatoshi; Fujita, Kazuhiro

    2011-01-01

    A new analytical method for the simultaneous determination of seven fluoroquinolones, namely, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, orbifloxacin, sarafloxacin, and difloxacin, especially in dark-colored honey, has been developed. Fluoroquinolone antibiotics were extracted from samples with MacIlvaine buffer solution (pH 4.0) containing EDTA disodium salt dihydrate. The extracts were treated with both a polymeric cartridge and a metal chelate affinity column preloaded with ferric ion (Fe3+). LC separation with fluorescence detection was performed at 40 degrees C using an Inertsil ODS-4 analytical column (150 x 4.6 mm, 3 microm). The mobile phase was composed of 20 mM/L citrate buffer solution (pH 3.1)-acetonitrile mixture (70 + 30, v/v) containing 1 mM/L sodium dodecyl sulfate. Lomefloxacin was used as an internal standard. The developed method was validated according to the criteria of European Commission Decision 2002/657/EC. Decision limits and detection capabilities were below 2.9 and 4.4 microg/kg, respectively.

  10. Zn(II)- and Cu(II)-induced non-fibrillar aggregates of amyloid-beta (1-42) peptide are transformed to amyloid fibrils, both spontaneously and under the influence of metal chelators.

    Science.gov (United States)

    Tõugu, Vello; Karafin, Ann; Zovo, Kairit; Chung, Roger S; Howells, Claire; West, Adrian K; Palumaa, Peep

    2009-09-01

    Aggregation of amyloid-beta (Abeta) peptides is a central phenomenon in Alzheimer's disease. Zn(II) and Cu(II) have profound effects on Abeta aggregation; however, their impact on amyloidogenesis is unclear. Here we show that Zn(II) and Cu(II) inhibit Abeta(42) fibrillization and initiate formation of non-fibrillar Abeta(42) aggregates, and that the inhibitory effect of Zn(II) (IC(50) = 1.8 micromol/L) is three times stronger than that of Cu(II). Medium and high-affinity metal chelators including metallothioneins prevented metal-induced Abeta(42) aggregation. Moreover, their addition to preformed aggregates initiated fast Abeta(42) fibrillization. Upon prolonged incubation the metal-induced aggregates also transformed spontaneously into fibrils, that appear to represent the most stable state of Abeta(42). H13A and H14A mutations in Abeta(42) reduced the inhibitory effect of metal ions, whereas an H6A mutation had no significant impact. We suggest that metal binding by H13 and H14 prevents the formation of a cross-beta core structure within region 10-23 of the amyloid fibril. Cu(II)-Abeta(42) aggregates were neurotoxic to neurons in vitro only in the presence of ascorbate, whereas monomers and Zn(II)-Abeta(42) aggregates were non-toxic. Disturbed metal homeostasis in the vicinity of zinc-enriched neurons might pre-dispose formation of metal-induced Abeta aggregates, subsequent fibrillization of which can lead to amyloid formation. The molecular background underlying metal-chelating therapies for Alzheimer's disease is discussed in this light.

  11. Characterization of changes in floc morphology, extracellular polymeric substances and heavy metals speciation of anaerobically digested biosolid under treatment with a novel chelated-Fe2+ catalyzed Fenton process.

    Science.gov (United States)

    He, Juanjuan; Yang, Peng; Zhang, Weijun; Cao, Bingdi; Xia, Hua; Luo, Xi; Wang, Dongsheng

    2017-11-01

    A novel chelated-Fe 2+ catalyzed Fenton process (CCFP) was developed to enhance dewatering performance of anaerobically digested biosolid, and changes in floc morphology, extracellular polymeric substances (EPS) and heavy metals speciation were also investigated. The results showed that addition of chelating agents caused EPS solubilization by binding multivalent cations. Like traditional Fenton, CCFP performed well in improving anaerobically digested sludge dewatering property. The highly active radicals (OH, O 2 - ) produced in classical Fenton and CCFP were responsible for sludge flocs destruction and consequently degradation of biopolymers into small molecules. Furthermore, more plentiful pores and channels were presented in cake after Fenton treatment, which was conducive to water drainage under mechanical compression. Additionally, a portion of active heavy metals in the form of oxidizable and reducible states were dissolved under CCFP. Therefore, CCFP could greatly simplify the operating procedure of Fenton conditioning and improve its process adaptability for harmless treatment of biological sludge. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor; Villalobos Vazquez de la Parra, Luis Francisco; Hilke, Roland

    2015-01-01

    microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  13. Synthesis of novel bifunctional chelators and their use in preparing monoclonal antibody conjugates for tumor targeting

    International Nuclear Information System (INIS)

    Westerberg, D.A.; Carney, P.L.; Rogers, P.E.; Kline, S.J.; Johnson, D.K.

    1989-01-01

    Bifunctional derivatives of the chelating agents ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, in which a p-isothiocyanatobenzyl moiety is attached at the methylene carbon atom of one carboxymethyl arm, was synthesized by reductive alkylation of the relevant polyamine with (p-nitrophenyl)pyruvic acid followed by carboxymethylation, reduction of the nitro group, and reaction with thiophosgene. The resulting isothiocyanate derivatives reacted with monoclonal antibody B72.3 to give antibody-chelator conjugates containing 3 mol of chelator per mole of immunoglobulin, without significant loss of immunological activity. Such conjugates, labeled with the radioisotopic metal indium-111, selectively bound a human colorectal carcinoma implanted in nude mice when given intravenously. Uptake into normal tissues was comparable to or lower than that reported for analogous conjugates with known bifunctional chelators. It is concluded that substitution with a protein reactive group at this position in polyaminopolycarboxylate chelators does not alter the chelating properties of these molecules to a sufficient extent to adversely affect biodistribution and thus provides a general method for the synthesis of such chelators

  14. Selective separation of indium by iminodiacetic acid chelating resin

    International Nuclear Information System (INIS)

    Fortes, M.C.B.; Benedetto, J.S.; Martins, A.H.

    2007-01-01

    - Indium can be recovered by treating residues, flue dusts, slags, and metallic intermediates in zinc smelting. This paper investigates the adsorption characteristics of indium and iron on an iminodiacetic acid chelating resin, Amberlite R IRC748 (Rohm and Haas Co.-USA). High concentrations of iron are always present in the aqueous feed solution of indium recovery. In addition, the chemical behaviour of iron in adsorptive systems is similar to that of indium. The metal concentrations in the aqueous solution were based on typical indium sulfate leach liquor obtained from zinc hydrometallurgical processing in a Brazilian plant. The ionic adsorption experiments were carried out by the continuous column method. Amberlite R IRC748 resin had a high affinity for indium under acidic conditions. Indium ions adsorbed onto the polymeric resin were eluted with a 0.5 mol/dm 3 sulphuric acid solution passed through the resin bed in the column. 99.5% pure indium sulfate aqueous solution was obtained using the iminodiacetic acid chelating resin Amberlite R IRC748. (author)

  15. Ruthenium(II) tris(2,2'-bipyridine) chelate as a chemiluminophore in extrinsic lyoluminescences of aluminium and magnesium in aqueous solution

    International Nuclear Information System (INIS)

    Jiang Qinghong; Kotiranta, Miia; Langel, Kaarina; Suomi, Johanna; Hakansson, Markus; Spehar, Anna-Maria; Ala-Kleme, Timo; Eskola, Jarkko; Kulmala, Sakari

    2005-01-01

    Ruthenium(II) tris(2,2'-bipyridine) chelate shows chemiluminescence (CL) both during dissolution of metallic aluminium in alkaline conditions, and during dissolution of magnesium metal in acidic conditions. The presence of peroxodisulfate ions strongly enhances the CL. Magnesium system provides considerably better detectability of the present chelate giving linear calibration plot spanning over many orders of magnitude of concentration down to subnanomolar concentration levels. The possible primary species generated and luminescence mechanisms are shortly discussed

  16. Isolation and Utilization of Corn Cobs Hemisellulose as Chelating Agent for Lead Ions

    International Nuclear Information System (INIS)

    Muchlisyam; Harahap, U; Silalahi, J.; Zul Alfian

    2013-01-01

    Corn cobs is an agricultural byproduct containing polysaccharide composed of cellulose, hemicelluloses and lignin. Hemicelluloses has a hydroxyl and carbonyl functional groups which can be used as chelating agent for metal ions. The purpose of this study was to isolate and evaluate corncobs hemicelluloses as a chelating agent toward lead ion. Graphite furnace spectrophotometry at 283.3 nm was used to determine the residual lead ion in solution. The research's result showed that the highest yield of hemicelluloses (12.04 %) was obtained from delignication with 0,03 M NaOH in 60 % ethanol and 3 % H 2 O 2 , hemicelluloses isolation with 500 ml of 0.2 M NaOH, and precipitation with 1:4 ratio of 10 % acetic acid in 95 % ethanol. The 300 mg corn cobs hemicelluloses has chelating effect for 40 mg lead solution at (39.52±0.1350) mg or 98.80 %, that the corn cobs hemicelluloses can be used as a chelating agent for lead. (author)

  17. Cathodic electrogenerated chemiluminescence of aromatic Tb(III) chelates at polystyrene-graphite composite electrodes

    International Nuclear Information System (INIS)

    Salminen, Kalle; Grönroos, Päivi; Tuomi, Sami; Kulmala, Sakari

    2017-01-01

    Tb(III) chelates exhibit intense hot electron-induced electrogenerated chemiluminescence during cathodic polarization of metal/polystyrene-graphite (M/PG) electrodes in fully aqueous solutions. The M/PG working electrode provides a sensitive means for the determination of aromatic Tb(III) chelates at nanomolar concentration levels with a linear log-log calibration curve spanning more than five orders of magnitude. The charge transport and other properties of these novel electrodes were studied by electrochemiluminescence measurements and cyclic voltammetry. The present composite electrodes can by utilized both under pulse polarization and DC polarization unlike oxide-coated metal electrodes which do not tolerate cathodic DC polarization. The present cost-effective electrodes could be utilized e.g. in immunoassays where polystyrene is extensively used as a solid phase for various bioaffinity assays by using electrochemiluminescent Tb(III) chelates or e.g. Ru(bpy) 3 2+ as labels. - Highlights: • Generation of hydrated electrons at Polystyrene-graphite electrodes. • The insulating polystyrene layer on the outer electrode surface seems necessary. • Hydrated electrons are able to produce chemiluminescence. • Strongest signal and lowest std. dev. achieved at same graphite weight fraction.

  18. Effectiveness of chelation therapy with time after acute uranium intoxication

    International Nuclear Information System (INIS)

    Domingo, J.L.; Ortega, A.; Llobet, J.M.; Corbella, J.

    1990-01-01

    The effect of increasing the time interval between acute uranium exposure and chelation therapy was studied in male Swiss mice. Gallic acid, 4,5-dihydroxy-1,3- benzenedisulfonic acid (Tiron), diethylenetriaminepentaacetic acid (DTPA), and 5-aminosalicylic acid (5-AS) were administered ip at 0, 0.25, 1, 4, and 24 hr after sc injection of 10 mg/kg of uranyl acetate dihydrate. Chelating agents were given at doses equal to one-fourth of their respective LD50 values. Daily elimination of uranium into urine and feces was determined for 4 days after which time the mice were killed, and the concentration of uranium was measured in kidney, spleen, and bone. The excretion of uranium was especially rapid in the first 24 hr. Treatment with Tiron or gallic acid at 0, 0.25, or 1 hr after uranium exposure significantly increased the total excretion of the metal. In kidney and bone, only administration of Tiron at 0, 0.25, or 1 hr after uranium injection, or gallic acid at 1 hr after uranium exposure significantly reduced tissue uranium concentrations. Treatment at later times (4 to 24 hr) did not increase the total excretion of the metal and did not decrease the tissue uranium concentrations 4 days after uranyl acetate administration. The results show that the length of time before initiating chelation therapy for acute uranium intoxication greatly influences the effectiveness of this therapy

  19. Chelation therapy and cardiovascular disease: connecting scientific silos to benefit cardiac patients.

    Science.gov (United States)

    Peguero, Julio G; Arenas, Ivan; Lamas, Gervasio A

    2014-08-01

    Medical practitioners have treated atherosclerotic disease with chelation therapy for over 50 years. Lack of strong of evidence led conventional practitioners to abandon its use in the 1960s and 1970s. This relegated chelation therapy to complementary and alternative medicine practitioners, who reported good anecdotal results. Concurrently, the epidemiologic evidence linking xenobiotic metals with cardiovascular disease and mortality gradually accumulated, suggesting a plausible role for chelation therapy. On the basis of the continued use of chelation therapy without an evidence base, the National Institutes of Health released a Request for Applications for a definitive trial of chelation therapy. The Trial to Assess Chelation Therapy (TACT) was formulated as a 2 × 2 factorial randomized controlled trial of intravenous EDTA-based chelation vs. placebo and high-dose oral multivitamins and multiminerals vs. oral placebo. The composite primary endpoint was death, reinfarction, stroke, coronary revascularization, or hospitalization for angina. A total of 1708 post-MI patients who were 50 years or older with a creatinine of 2.0 or less were enrolled and received 55,222 infusions of disodium EDTA or placebo with a median follow-up of 55 months. Patients were on evidence-based post-MI medications including statins. EDTA proved to be safe. EDTA chelation therapy reduced cardiovascular events by 18%, with a 5-year number needed to treat (NNT) of 18. Prespecified subgroup analysis revealed a robust benefit in patients with diabetes mellitus with a 41% reduction in the primary endpoint (5-year NNT = 6.5), and a 43% 5-year relative risk reduction in all-cause mortality (5-year NNT = 12). The magnitude of benefit is such that it suggests urgency in replication and implementation, which could, due to the excellent safety record, occur simultaneously. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Deaths associated with hypocalcemia from chelation therapy--Texas, Pennsylvania, and Oregon, 2003-2005.

    Science.gov (United States)

    2006-03-03

    Chelating agents bind lead in soft tissues and are used in the treatment of lead poisoning to enhance urinary and biliary excretion of lead, thus decreasing total lead levels in the body. During the past 30 years, environmental and dietary exposures to lead have decreased substantially, resulting in a considerable decrease in population blood lead levels (BLLs) and a corresponding decrease in the number of patients requiring chelation therapy. Chelating agents also increase excretion of other heavy metals and minerals, such as zinc and, in certain cases, calcium. This report describes three deaths associated with chelation-therapy--related hypocalcemia that resulted in cardiac arrest. Several drugs are used in the treatment of lead poisoning, including edetate disodium calcium (CaEDTA), dimercaperol (British anti-Lewisite), D-penicillamine, and meso-2,3-dimercaptosuccinic acid (succimer). Health-care providers who are unfamiliar with chelating agents and are considering this treatment for lead poisoning should consult an expert in the chemotherapy of lead poisoning. Hospital pharmacies should evaluate whether continued stocking of Na2EDTA is necessary, given the established risk for hypocalcemia, the availability of less toxic alternatives, and an ongoing safety review by the Food and Drug Administration (FDA). Health-care providers and pharmacists should ensure that Na2EDTA is not administered to children during chelation therapy.

  1. Effects of some chelating agents on the uptake and distribution of 54Mn(II) in the brown trout (Salmo trutta)

    International Nuclear Information System (INIS)

    Rouleau, C.; Tjaelve, H.; Pelletier, E.; Gottofrey, J.

    1994-01-01

    The effects of humic acids, which are natural metal-complexing compounds, and potassium ethylxanthate, sodium diethyldithiophosphate, sodium dimethyldithicarbamate, which are sulphur-containing man-made chelating agents, on the uptake and tissue distribution of 54 Mn(II) were studied in brown trout (Salmo trutta). Fish were exposed for 7 days to 0.1 μg Mn(II)x. -2 as NmCl 2 (l μCia 54 Mnxl -1 ) with or without chelat agents. Examination of the partition of Mn between octanol and a Tris-HCl buffer in the presence of these compounds was also performed. Humic acids had only small effects on Mn uptake and distribution in trout, probably because of the low stability of Mn-humate complexes. Partition of Mn in the presence of potassium ethylxanthate, sodium diethyldithiophosphate, sodium dimethyldithiocarbamate, and sodium diethyldithiocarbamate between octanol and Tris-HCl buffer showed formation of lipophilic complex with the latter two compounds, but not with the former. However, these four chelating agents all decreased Mn uptake in the trout by 40-45%. These substances also changed the distribution of Mn within the fish, with a higher proportion of the metal being present in some visceral organs and a smaller proportion being localized in some non-parenchymateous tissues, such as skin, fins and bones. The mechanisms underlying these effects are not known. however, the interaction of chelating agents with the Mn, although weak, may have partially withdrawn the metal from the uptake process inthe gills. The redistribution of Mn in the fish may be due to the binding of the metal to complexing compounds which have reached the intestinal lumen. Previous studies with other metals have shown increased or unchanged metal levels in tissues of fish at exposure together with potasium ethylxanthate, sodium diethyldithiophosphate, sodium dimethyldithiocarbamate, and sodium diethyldithiocarbamate, but decreased metal levels have not been observed before. (au) (37 refs.)

  2. Chelation Ion Exchange Properties of 2, 4-Dihydroxyacetophenone-Biuret-Formaldehyde Terpolymer Resin

    Directory of Open Access Journals (Sweden)

    Sanjiokumar S. Rahangdale

    2009-01-01

    Full Text Available The terpolymer resin 2, 4-HABF has been synthesized by the condensation of 2, 4-dihydroxyacetophenone (2, 4-HA and biuret (B with formaldehyde (F in 1:1:2 molar ratios in presence of 2 M hydrochloric acid as catalyst. UV-Visible, IR and proton NMR spectral studies have been carried out to elucidate the structure of the resin. A terpolymer (2, 4-HABF proved to be a selective chelating ion exchange polymer for certain metals. Chelating ion-exchange properties of this polymer were studied for Fe3+, Cu2+, Ni2+, Co2+, Zn2+, Cd2+ and Pb2+ ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake involving the measurement of the distribution of a given metal ion between the polymer sample and a solution containing the metal ion. The study was carried out over a wide pH range and in media of various ionic strengths. The polymer showed highest selectivity for Fe3+, Cu2+ ions than for Ni2+, Co2+, Zn2+, Cd2+, and Pb2+ ions. Study of distribution ratio as a formation of pH indicates that the amount of metal ion taken by resin is increases with the increasing pH of the medium.

  3. Chelate forms of biometalls. Theoretical aspects of obtaining and characteristics

    Directory of Open Access Journals (Sweden)

    A. Kapustyan

    2017-04-01

    Full Text Available The problem of microelements bioavailability is highlighted and the correct ways of its solution are substantiated as a result of generalization of theoretical aspects of obtaining of the biometals chelate forms. The characteristics of the main biogenic elements, their physiological significance, electrochemical properties are presented. The main examples of the participation of biometals in various biological processes are given. The properties and the structure peculiarities of biometals coordination complexes are considered in detail. It is shown that in obtaining of biometals chelate forms, there is the mutual selectivity and the affinity of biometals and ligands. The main factors of obtaining a hard metal complex are given. Potential bioligands for obtaining bioavailable forms of microelements are detailed. Among them there are amino acids, peptides, proteins, nucleic acids, carbohydrates. The possible character of complexation depending on the nature of the bioligand is indicated. Practical examples of preparation of biometals mixed ligand complexes are given. The expediency of using metabolic products and processing of lactic acid bacteria as promising components of mixed ligand chelate complexes is substantiated. These substances contain in their composition a mass of potential donor atoms that are capable to form covalent and coordination bonds with biomethalles, and also possess high biological and immunotropic activities. The use of this system in the biocoordination compounds of the "metals of life" can provide a synergistic effect of the components, significantly to expand the range of their physiological activity and to increase the degree of assimilation by the body.

  4. Chelating water-soluble polymers for waste minimization

    International Nuclear Information System (INIS)

    Smith, B.; Cournoyer, M.; Duran, B.; Ford, D.; Gibson, R.; Lin, M.; Meck, A.; Robinson, P.; Robison, T.

    1996-01-01

    Within the DOE complex and in industry there is a tremendous need for advanced metal ion recovery and waste minimization techniques. This project sought to employ capabilities for ligand-design and separations chemistry in which one can develop and evaluate water- soluble chelating polymers for recovering actinides and toxic metals from various process streams. Focus of this work was (1) to develop and select a set of water-soluble polymers suitable for a selected waste stream and (2) demonstrate this technology in 2 areas: removal of (a) actinides and toxic RCRA metals from waste water and (b) recovery of Cu and other precious metals from industrial process streams including from solid catalysts and aqueous waste streams. The R ampersand D was done in 4 phases for each of the 2 target areas: polymer synthesis for scaleup, equipment assembly, process demonstration at a DOE or industrial site, and advanced ligand/polymer synthesis. The TA- 50 site at Los Alamos was thought to be appropriate due to logistics and to its being representative of similar problems throughout the DOE complex

  5. Site-activated chelators derived from anti-Parkinson drug rasagiline as a potential safer and more effective approach to the treatment of Alzheimer's disease.

    Science.gov (United States)

    Zheng, Hailin; Fridkin, Mati; Youdim, Moussa B H

    2010-12-01

    chelators can modulate β-amyloid accumulation, protect against tau hyperphosphorylation, and block metal-related oxidative stress, and thereby hold considerable promise as effective anti-AD drugs. At present, a growing interest is focusing on increasing the efficacy and targeting of chelators through drug design. To this end, we have developed a new class of multifunctional prochelators from three FDA- approved drugs rasagiline, rivastigmine, and donepezil or tacrine. HLA20 A was designed by merging the important pharmacophores of rasagiline, rivastigmine, and donepezil into our newly developed multifunctional chelator HLA20. M30D was constructed using the key pharmacophoric moieties from rasagiline, rivastigmine, and tacrine. Experiments showed that both compounds possess potent anti-acetylcholinesterase (AChE) activity in vitro with weak inhibition of butyrylcholinesterase (BuChE), and without significant metal-binding activity. M30D was found also to be a highly potent MAO A inhibitor with moderate inhibition of MAO B in vitro. Both HLA20 and M30D can be activated by inhibition of AChE to release active chelators HLA20 and M30, respectively. HLA20 and M30 have been shown to be able to modulate amyloid precursor protein regulation and beta-amyloid reduction, suppress oxidative stress, and passivate excess metal ions (Fe, Cu, and Zn). Compared with the activated chelator HLA20 or M30, both HLA20A and M30D exhibited lower cytotoxicity in SH-SY5Y neuroblastoma cells, substantiating the prochelator strategy for minimizing toxicity associated with poor targeted chelators.

  6. Heavy metal toxicity and iron chlorosis

    Energy Technology Data Exchange (ETDEWEB)

    DeKock, P C

    1956-01-01

    The toxicity of copper, nickel, cobalt, zinc, chromium, and manganese to mustard was studied in water culture, utilizing either the ionic form or the EDTA chelate of the metal in the presence of either ferric chloride or ferric EDTA. In presence of ferric chloride the activity of the metals in producing chlorosis was as given above, i.e. in the order of stability of their chelates. In the presence of ferric versenate, toxicity of the ionic metal was much reduced. The metal chelates gave very little indication of toxicity with either form of iron. It was found that the ratio of total phosphorus to total iron was higher in chlorotic plants than in green plants, irrespective of which metal was causing the toxicity. Copper could be demonstrated in the phloem cells of the root using biscyclohexanone-oxalydihydrazone as histochemical reagent. It is postulated that transport of iron probably takes place in the phloem as an active process. It would appear that as a major part of the iron in plant cells is attached to nucleo- or phospho-proteins, the heavy metals must be similarly attached to phospho-proteins.

  7. A study on the adsorption and subsurface transport of radioactive solutes in the presence of chelating agents

    International Nuclear Information System (INIS)

    Baik, Min Hoon

    1994-02-01

    In this study, adsorption and transport models were developed to analyze the effect of chelating agents on the adsorption and subsurface transport of radioactive solutes. The effect of chelating agents on the adsorption of radioactive solutes was analyzed by developing an adsorption model based upon the extended concept of distribution coefficient reflecting the presence of chelating agents. Also, a batch adsorption experiment was conducted in order to validate the developed adsorption model and to investigate the effect of chelating agent on the adsorption of radioactive metal solutes. In this experiment, a Cobalt(II)/EDTA/Bentonite system was considered as a representative chelation/adsorption system. It was found from the results that the presence of chelating agents significantly reduced the adsorbing capacity of geologic media such as clay minerals and soils. Thus it was concluded that the presence of chelating agents even in a small amount could contribute to the mobilization of radioactive solutes from radioactive waste burial sites by reducing the adsorbing capacity of geologic media. The effect of chelating agents on the transport of radioactive solutes in subsurface porous media was analyzed by formulating an advective-dispersive transport model which incorporated chelate formation, adsorption, decay, and degradations and by introducing the concept of a tenad. Particularly the governing equation for the tenad of radioactive solutes, M, was presented as a linear partial differential form by introducing the extended distribution coefficient, K D . The calculated results from the model showed that the transport rate of the chelated radionuclides was much greater than that of the free ionic radionuclides. This much faster transport of the chelated radionuclides was found to be due to the lower retardation factor of the chelated radionuclides than the free ionic radionuclides. The effect of parameters on the transport of radioactive solutes was also analyzed

  8. Beliefs about chelation among thalassemia patients

    Directory of Open Access Journals (Sweden)

    Trachtenberg Felicia L

    2012-12-01

    Full Text Available Abstract Background Understanding patients’ views about medication is crucial to maximize adherence. Thalassemia is a congenital blood disorder requiring chronic blood transfusions and daily iron chelation therapy. Methods The Beliefs in Medicine Questionnaire (BMQ was used to assess beliefs in chelation in thalassemia patients from North America and London in the Thalassemia Longitudinal Cohort (TLC of the Thalassemia Clinical Research Network (TCRN. Chelation adherence was based on patient report of doses administered out of those prescribed in the last four weeks. Results Of 371 patients (ages 5-58y, mean 24y, 93% were transfused and 92% receiving chelation (26% deferoxamine (DFO; a slow subcutaneous infusion via portable pump, 63% oral, 11% combination. Patients expressed high “necessity” for transfusion (96%, DFO chelation (92% and oral chelation (89%, with lower “concern” about treatment (48%, 39%, 19% respectively. Concern about oral chelation was significantly lower than that of DFO (p Conclusions Despite their requirement for multimodal therapy, thalassemia patients have positive views about medicine, more so than in other disease populations. Patients may benefit from education about the tolerability of chelation and strategies to effectively cope with side effects, both of which might be beneficial in lowering body iron burden. Clinicaltrials.gov identifier NCT00661804

  9. Chelation: A Fundamental Mechanism of Action of AGE Inhibitors, AGE Breakers, and Other Inhibitors of Diabetes Complications

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, Rhoji; Murray, David B.; Metz, Thomas O.; Baynes, John

    2012-03-01

    Advanced glycation or glycoxidation end-products (AGE) increase in tissue proteins with age, and their rate of accumulation is increased in diabetes, nephropathy and inflammatory diseases. AGE inhibitors include a range of compounds that are proposed to act by trapping carbonyl and dicarbonyl intermediates in AGE formation. However, some among the newer generation of AGE inhibitors lack reactive functional groups that would trap reaction intermediates, indicating an alternative mechanism of action. We propose that AGE inhibitors function primarily as chelators, inhibiting metal-catalyzed oxidation reactions. The AGE-inhibitory activity of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers is also consistent with their chelating activity. Finally, compounds described as AGE breakers, or their hydrolysis products, also have strong chelating activity, suggesting that these compounds also act through their chelating activity. We conclude that chelation is the common, and perhaps the primary, mechanism of action of AGE inhibitors and breakers, and that chronic, mild chelation therapy should prove useful in treatment of diabetes and age-related diseases characterized by oxidative stress, inflammation and increased chemical modification of tissue proteins by advanced glycoxidation and lipoxidation end-products.

  10. Immobilization of Fe chelators on sepharose gel and its effect on their chemical properties.

    Science.gov (United States)

    Yehuda, Zehava; Hadar, Yitzhak; Chen, Yona

    2003-09-24

    Iron chelates are usually costly and easily leached beyond the root zone. This creates a need to frequently replenish the rhizosphere with chelated Fe and might contaminate groundwater with organic compounds and metals. The development of a slow-release Fe fertilizer that will efficiently supply Fe to plants while exhibiting high resistance toward leaching and/or degradation in the rhizosphere has been the focus of this study. Desferrioxamine B (DFOB) and ethylenediaminebis(o-hydroxyphenylacetic acid) (EDDHA) were immobilized on Sepharose. (13)C NMR and FTIR measurements confirmed that coupling of DFOB to the gel did not appear to influence its ability to chelate Fe(3+) or its binding nature. Isotherms for the immobilized ligands were determined in the presence of 1 mM HEDTA, at 25 degrees C and at an ionic strength of 0.1 M. The isotherms showed a high affinity of Fe(3+) to the ligands and binding up to saturation level throughout the pH range examined (4.0-9.0). The K(app) values for the immobilized Fe chelates were determined using a modified Scatchard model and found to be lower than the soluble ones. This decrease in K(app) might facilitate Fe uptake from these chelates by plants.

  11. The interactive effects of chelator, fertilizer, and rhizobacteria for enhancing phytoremediation of heavy metal contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.; Cutright, T.J. [Dept. of Civil Engineering, Univ. of Akron, Akron, OH (United States)

    2002-07-01

    The role of chelator, fertilizer, and enriched rhizobacteria in facilitating Cd, Cr, and Ni accumulation by Helianthus annuus was studied. It was found that by adding a synthetic chelator, EDTA, the shoot concentrations of Cd and Ni were significantly increased from 34.2 mg kg{sup -1} and 14.5 mg kg{sup -1} to 115 mg kg{sup -1} and 117 mg kg{sup -1}, respectively. However, the total biomass of plants was drastically decreased by 50 to 60%. Compared with this treatment, inoculating enriched rhizobacteria to plants grown under similar conditions maintained the surged shoot concentrations of Cd and Ni while increasing the plants biomass by more than 1.6-fold. It was also found that introducing a commercial fertilizer, Hydro-Gro trademark, to plants significantly increased the Ni accumulation by 3-fold and the plant biomass by 1.43-fold. These results suggest that combing fertilizers, chelators and/or rhizobacteria might provide a more effective approach for enhancing phytoremediation. (orig.)

  12. Effect of soil washing with only chelators or combining with ferric chloride on soil heavy metal removal and phytoavailability: Field experiments.

    Science.gov (United States)

    Guo, Xiaofang; Wei, Zebin; Wu, Qitang; Li, Chunping; Qian, Tianwei; Zheng, Wei

    2016-03-01

    In a field experiment on multi-metal contaminated soil, we investigated the efficiency of Cd, Pb, Zn, and Cu removal by only mixture of chelators (MC) or combining with FeCl3. After washing treatment, a co-cropping system was performed for heavy metals to be extracted by Sedum alfredii and to produce safe food from Zea mays. We analyzed the concentration of heavy metals in groundwater to evaluate the leashing risk of soil washing with FeCl3 and MC. Results showed that addition of FeCl3 was favorable to the removal of heavy metals in the topsoil. Metal leaching occurred mainly in rain season during the first co-cropping. The removal rates of Cd, Zn, Pb, and Cu in topsoil were 28%, 53%, 41%, and 21% with washing by FeCl3+MC after first harvest. The application of FeCl3 reduced the yield of S. alfredii and increased the metals concentration of Z. mays in first harvest. However, after amending soil, the metals concentration of Z. mays in FeCl3+MC treatment were similar to that only washing by MC. The grains and shoots of Z. mays were safe for use in feed production. Soil washing did not worsen groundwater contamination during the study period. But the concentration of Cd in groundwater was higher than the limit value of Standard concentrations for Groundwater IV. This study suggests that soil washing using FeCl3 and MC for the remediation of multi-metal contaminated soil is potential feasibility. However, the subsequent measure to improve the washed soil environment for planting crop is considered. Copyright © 2016. Published by Elsevier Ltd.

  13. F-Element ion chelation in highly basic media. Annual progress report, October 1, 1996 - July 1, 1997

    International Nuclear Information System (INIS)

    Paine, R.T.

    1997-01-01

    'The specific fundamental chemical objectives of this project are to: (1) study the chemical speciation of Sr and Ln ions in basic media formed in aqueous solutions with and without classical chelation agents (e.g., EDTA, polyphosphates, and organic carboxylates); (2) prepare pyridine N-oxide phosphonate and phosphonoacetate chelators of the types 1--3 and characterize their ionization properties by titrimetric techniques; (3) study the interactions of 5--7 with soluble oxide-hydroxide metallate species and higher molecular weight sols, gels and precipitates containing Sr and Ln ions, as time permits, interactions with oxide-hydroxide metallates of U, Th, Ba, Al and Fe will also be studied; (4) study the interactions of newly designed phosphonate ligands with oxide-hydroxide metallate species; (5) transfer the fundamental coordination chemistry revealed here to research groups at LANL and PNNL that will utilize the results to improve tank waste treatment protocols.'

  14. Synthesis of LaNiO3 perovskite type by chelating precursor method using EDTA: optimization of chelating content

    International Nuclear Information System (INIS)

    Santos, Jose Carlos dos; Pedrosa, Anne Michelle Garrido; Mesquita, Maria Eliane; Souza, Marcelo Jose Barros de

    2011-01-01

    The perovskites are strategic materials due their catalytic, electronic and magnetic properties. These properties are influenced by the calcination and synthesis conditions. In this work was carried out the synthesis of LaNiO 3 perovskite type by chelating precursor method using EDTA and also was studied the optimization of the EDTA content in the synthesis. The synthesized materials were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TG) and Infrared Spectroscopy (FTIR). In the optimization of the EDTA content the lowest ratio of metal / EDTA used was 1.0 / 0.1, where it was possible to obtain monophasic perovskite. (author)

  15. Bis-phosphonate sequestering agents. Synthesis and preliminary evaluation for in vitro and in vivo uranium(VI) chelation

    Energy Technology Data Exchange (ETDEWEB)

    Sawicki, M.; Lecercle, D.; Taran, F. [CEA Saclay, IBiTecS, Serv Chim Bioorgan et Marquage, F-91191 Gif Sur Yvette (France); Grillon, G.; Le Gall, B.; Serandour, A.L.; Poncy, J.L. [CEA, DSV, DRR, Lab Radiotoxicol, F-91680 Bruyeres Le Chatel (France); Bailly, T.; Burgada, R.; Lecouvey, M.; Challeix, V. [CNRS, Lab Chim Struct Biomol, UMR 7033, F-93017 Bobigny (France); Leydier, A.; Pellet-Rostaing, S. [Univ Lyon 1, ICBMS, UMR 5246, Lab Catalyse et Synth Organ, F-69622 Villeurbanne (France); Ansoborlo, E. [CEA, DEN, DRCP, CETAMA, VRH Marcoule, F-30207 Bagnols Sur Ceze (France)

    2008-07-01

    A library of bis-phosphonate-based ligands was prepared using solution-phase parallel synthesis and tested for its uranium-binding properties. With the help of a screening method, based on a chromo-phoric complex displacement procedure, 23 dipodal and tripodal chelates bearing bis-phosphonate chelating functions were found to display very high affinity for the uranyl ion and were selected for evaluation of their in vivo uranyl-removal efficacy. Among them, 11 ligands induced a huge modification of the uranyl biodistribution by deviating the metal from kidney and bones to liver. Among the other ligands, the most potent was the dipodal bis-phosphonate 3C which reduced the retention of uranyl and increased its excretion by around 10% of the injected metal. (authors)

  16. Chiral DOTA chelators as an improved platform for biomedical imaging and therapy applications.

    Science.gov (United States)

    Dai, Lixiong; Jones, Chloe M; Chan, Wesley Ting Kwok; Pham, Tiffany A; Ling, Xiaoxi; Gale, Eric M; Rotile, Nicholas J; Tai, William Chi-Shing; Anderson, Carolyn J; Caravan, Peter; Law, Ga-Lai

    2018-02-27

    Despite established clinical utilisation, there is an increasing need for safer, more inert gadolinium-based contrast agents, and for chelators that react rapidly with radiometals. Here we report the syntheses of a series of chiral DOTA chelators and their corresponding metal complexes and reveal properties that transcend the parent DOTA compound. We incorporated symmetrical chiral substituents around the tetraaza ring, imparting enhanced rigidity to the DOTA cavity, enabling control over the range of stereoisomers of the lanthanide complexes. The Gd chiral DOTA complexes are shown to be orders of magnitude more inert to Gd release than [GdDOTA] - . These compounds also exhibit very-fast water exchange rates in an optimal range for high field imaging. Radiolabeling studies with (Cu-64/Lu-177) also demonstrate faster labelling properties. These chiral DOTA chelators are alternative general platforms for the development of stable, high relaxivity contrast agents, and for radiometal complexes used for imaging and/or therapy.

  17. Determination of trace elements in seawater by air-flow injection/ICP-MS with chelating resin preconcentration

    International Nuclear Information System (INIS)

    Lee, Kyue-Hyung; Ohshima, Mitsuko; Motomizu, Shoji

    2002-01-01

    Multielement determination of major to trace metals in a deep seawater malt was accomplished by inductively coupled plasma-mass spectrometry (ICP-MS) together with inductively coupled plasma-atomic emission spectrometry (ICP-AES). Major elements, such as Na, K, Mg, and Ca, were measured by ICP-AES and normal continuos nebulization ICP-MS after sample dilution by 10 3 -10 6 fold. Fifteen trace elements in the concentrated metal solutions pretreated with cation-exchange resin or chelating resin could be simultaneously determined by air-flow injection/ICP-mass spectrometry (AFI/ICP-MS). Since the injection volume for AFI/ICP-MS was 25 μl, final samples volumes less than 500 μl were enough for several replicate measurements. Three different preconcentration methods assisted with AFI/ICP-MS were examined and could be successfully applied to a deep seawater malt. The analytical results of rate earth elements (REEs) and Co, Ni, Cu, Zn, Cd, and Pb obtained by AFI/ICP-MS coupled with disk filtration method using iminodiacetate (IDA)-type chelating resin were favorably agreed with the data obtained by AFI/ICP-MS coupled with column preconcentration method using chitosan-based chelating resin. (author)

  18. Removal effectiveness and mechanisms of naphthalene and heavy metals from artificially contaminated soil by iron chelate-activated persulfate

    International Nuclear Information System (INIS)

    Yan, Dickson Y.S.; Lo, Irene M.C.

    2013-01-01

    The effectiveness and mechanisms of naphthalene and metal removal from artificially contaminated soil by FeEDTA/FeEDDS-activated persulfate were investigated through batch experiments. Using FeEDTA-activated persulfate, higher naphthalene removal from the soil at 7 h was achieved (89%), compared with FeEDDS-activated persulfate (75%). The removal was mainly via the dissolution of naphthalene partitioned on mineral surfaces, followed by activated persulfate oxidation. Although EDDS is advantageous over EDTA in terms of biodegradability, it is not preferable for iron chelate-activated persulfate oxidation since persulfate was consumed to oxidize EDDS, resulting in persulfate inadequacy for naphthalene oxidation. Besides, 55 and 40% of naphthalene were removed by FeEDTA and FeEDDS alone, respectively. Particularly, 21 and 9% of naphthalene were degraded in the presence of FeEDTA and FeEDDS alone, respectively, which caused by electrons transfer among dissolved organic matter, Fe 2+ /Fe 3+ and naphthalene. Over 35, 36 and 45% of Cu, Pb and Zn were removed using FeEDTA/FeEDDS-activated persulfate. -- Highlights: ► FeEDTA/FeEDDS-activated persulfate oxidation removed PAH and heavy metal from soil. ► More naphthalene was removed by FeEDTA-activated persulfate compared to FeEDDS. ► Persulfate was consumed to oxidize EDDS in FeEDDS-activated persulfate oxidation. ► Metals can be extracted from soil by free EDTA/EDDS dissociated from FeEDTA/FeEDDS. ► Naphthalene oxidation can be induced by e − transfer among Fe 2+ , DOM and naphthalene. -- This study focuses on the potencies and mechanisms of naphthalene and metal removal from contaminated soil by FeEDTA/FeEDDS-activated persulfate

  19. Combined chelation based on glycosyl-mono- and bis-hydroxypyridinones for aluminium mobilization: solution and biodistribution studies.

    Science.gov (United States)

    Chaves, Sílvia; Dron, Paul I; Danalache, Florina A; Sacoto, Diana; Gano, Lurdes; Santos, M Amélia

    2009-11-01

    Taking into account the recognized interest of a poly-pharmacological strategy in chelation therapy, a study of aluminium combined chelation based on 3-hydroxy-4-pyridinone (3,4-HP) compounds with complementary properties, associated to different denticity, size and extrafunctionality, is presented herein. In particular, Al-chelation has been explored, using a tetradentate IDA bis-(3,4-HP) ligand, L, and two N-glycosyl mono-(3,4-HP) derivatives (A or B). Combined complexation studies with the tetradentate and the most promising bidentate ligand (A) evidenced the formation of ternary complexes with high thermodynamic stability (Al-L-A) being the predominant species at physiological pH. In vivo studies on the ability for radiotracer ((67)Ga) removal from loaded mice, as a model of aluminium accumulation in body, have shown that the simultaneous administration to (67)Ga-loaded mice of a mono- and a bis-(3,4-HP) chelator (e.g. A and L) leads to a rapid metal elimination from main organs and whole animal model. This may be rationalized by coadjuvation and eventual synergistic effects, due to complementary accessibility of the chelators to different cellular compartments.

  20. Activation of the CXCR3 chemokine receptor through anchoring of a small molecule chelator ligand between TM-III, -IV, and -VI

    DEFF Research Database (Denmark)

    Rosenkilde, Mette M; Andersen, Michael B; Nygaard, Rie

    2006-01-01

    modeling and molecular simulations combined with mutational analysis indicated that the metal ion site-anchored chelators act as agonists by establishing an aromatic-aromatic, second-site interaction with TyrVI:16 on the inner face of TM-VI. It is noteworthy that this interaction required......Seven transmembrane segment (7TM) receptors are activated through a common, still rather unclear molecular mechanism by a variety of chemical messengers ranging from monoamines to large proteins. By introducing a His residue at position III:05 in the CXCR3 receptor a metal ion site was built...... between the extracellular ends of transmembrane (TM) III and TM-IV to anchor aromatic chelators at a location corresponding to the presumed binding pocket for adrenergic receptor agonists. In this construct, free metal ions had no agonistic effect in accordance with the optimal geometry of the metal ion...

  1. Physicochemical, antioxidant, DNA cleaving properties and antimicrobial activity of fisetin-copper chelates.

    Science.gov (United States)

    Łodyga-Chruscińska, Elżbieta; Pilo, Maria; Zucca, Antonio; Garribba, Eugenio; Klewicka, Elżbieta; Rowińska-Żyrek, Magdalena; Symonowicz, Marzena; Chrusciński, Longin; Cheshchevik, Vitalij T

    2018-03-01

    Fisetin (3,3',4',7-tetrahydroxyflavone) metal chelates are of interest as this plant polyphenol has revealed broad prospects for its use as natural medicine in the treatment of various diseases. Metal interactions may change or enhance fisetin biological properties so understanding fisetin metal chelation is important for its application not only in medicine but also as a food additive in nutritional supplements. This work was aimed to determine and characterize copper complexes formed in different pH range at applying various metal/ligand ratios. Fisetin and Cu(II)-fisetin complexes were characterized by potentiometric titrations, UV-Vis (Ultraviolet-visible spectroscopy), EPR, ESI-MS, FTIR and cyclic voltammetry. Their effects on DNA were investigated by using circular dichroism, spectrofluorimetry and gel electrophoresis methods. The copper complex with the ratio of Cu(II)/fisetin 1/2 exhibited significant DNA cleavage activity, followed by complete degradation of DNA. The influence of copper(II) ions on antioxidant activity of fisetin in vitro has been studied using DPPH, ABTS and mitochondrial assays. The results have pointed out that fisetin or copper complexes can behave both as antioxidants or pro-oxidants. Antimicrobial activity of the compounds has been investigated towards several bacteria and fungi. The copper complex of Cu(II)/fisetin 1/2 ratio showed higher antagonistic activity against bacteria comparing to the ligand and it revealed a promising antifungal activity. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Trace metals analysis in estuarine and seawater by ICP-MS using on line preconcentration and matrix elimination with chelating resin.

    Science.gov (United States)

    Nicolaı, M; Rosin, C; Tousset, N; Nicolai, Y

    1999-09-13

    The main difficulties of trace metals analysis in estuarine and seawater stem from their very low concentration (mug/l to sub-mug/l), and, by contrast, the high salt content (up to 38 g/l in the Mediterranean Sea). ICP-MS allows multi-elemental analysis and offers great sensitivity, but may be strongly affected by matrix effects induced by high salt contents (> 1 g/l). To perform trace metals analysis both in riverine, estuarine and seawater, we have developed a hyphenated method: ion chelation chromatography coupled on-line with ICP-MS. Iminodiacetate resin, Metpac CC-1 (Dionex), was used to concentrate most of the trace metals, and to separate them from alkaline and alkaline-earth metals. Behaviour of 17 elements (Pb, Cu, Cd, Ni, U, Cr, Mn, Al, Co, Ga, In, Zn, V, Tl, Bi, Ag and Sn) towards the resin was qualitatively investigated. A method validation, partly derived from AFNOR standard XPT 90-210, was carried out on 12 elements (Pb, Cu, Cd, Ni, U, Cr, Mn, Al, Co, Ga, Bi and In). Replicate measurements of multi-elemental standard solutions were used to check linearity, and to determine repeatability and detection limits. Method accuracy was then assessed by analysing two certified materials: a synthetic freshwater (SRM 1643d), and a natural filtered coastal seawater (NRCC CASS-3). An application assay of natural samples from the Rhône river (France) was eventually carried out, and the analytical results were found to be consistent with previous works.

  3. Grammatical and pragmatic properties of the DP in children with Specific Language Impairment (SLI) and in children with High Functioning Autism (HFA)

    NARCIS (Netherlands)

    Creemers, A.; Schaeffer, J.C.; Köhnlein, B.; Audring, J.

    2015-01-01

    This study investigates whether grammar and pragmatics are separate linguistic components or not, and whether children with SLI and children with HFA have overlapping or distinct linguistic profiles. We examine two DP-related phenomena: the mass-count distinction (grammatical) and the choice for a

  4. Reversible adsorption of catalase onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogels.

    Science.gov (United States)

    Aktaş Uygun, Deniz; Uygun, Murat; Akgöl, Sinan; Denizli, Adil

    2015-05-01

    In this presented study, poly(acrylamide-glycidyl methacrylate) [poly(AAm-GMA)] cryogels were synthesized by cryopolymerization technique at sub-zero temperature. Prepared cryogels were then functionalized with iminodiacetic acid (IDA) and chelated with Fe(3+) ions in order produce the metal chelate affinity matrix. Synthesized cryogels were characterized with FTIR, ESEM and EDX analysis, and it was found that the cryogel had sponge like structure with interconnected pores and their pore diameter was about 200 μm. Fe(3+) chelated poly(AAm-GMA)-IDA cryogels were used for the adsorption of catalase and optimum adsorption conditions were determined by varying the medium pH, initial catalase concentration, temperature and ionic strength. Maximum catalase adsorption onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was found to be 12.99 mg/g cryogel at 25 °C, by using pH 5.0 acetate buffer. Adsorbed catalase was removed from the cryogel by using 1.0M of NaCl solution and desorption yield was found to be 96%. Additionally, reusability profile of the Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was also investigated and it was found that, adsorption capacity of the cryogels didn't decrease significantly at the end of the 40 reuses. Catalase activity studies were also tested and it was demonstrated that desorbed catalase retained 70% of its initial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. CaNa2EDTA chelation attenuates cell damage in workers exposed to lead--a pilot study.

    Science.gov (United States)

    Čabarkapa, A; Borozan, S; Živković, L; Stojanović, S; Milanović-Čabarkapa, M; Bajić, V; Spremo-Potparević, B

    2015-12-05

    Lead induced oxidative cellular damage and long-term persistence of associated adverse effects increases risk of late-onset diseases. CaNa2EDTA chelation is known to remove contaminating metals and to reduce free radical production. The objective was to investigate the impact of chelation therapy on modulation of lead induced cellular damage, restoration of altered enzyme activities and lipid homeostasis in peripheral blood of workers exposed to lead, by comparing the selected biomarkers obtained prior and after five-day CaNa2EDTA chelation intervention. The group of smelting factory workers diagnosed with lead intoxication and current lead exposure 5.8 ± 1.2 years were administered five-day CaNa2EDTA chelation. Elevated baseline activity of antioxidant enzymes Cu, Zn-SOD and CAT as well as depleted thiols and increased protein degradation products-carbonyl groups and nitrites, pointing to Pb induced oxidative damage, were restored toward normal values following the treatment. Lead showed inhibitor potency on both RBC AChE and BChE in exposed workers, and chelation re-established the activity of BChE, while RBC AChE remained unaffected. Also, genotoxic effect of lead detected in peripheral blood lymphocytes was significantly decreased after therapy, exhibiting 18.9% DNA damage reduction. Administration of chelation reversed the depressed activity of serum PON 1 and significantly decreased lipid peroxidation detected by the post-chelation reduction of MDA levels. Lactate dehydrogenase LDH1-5 isoenzymes levels showed evident but no significant trend of restoring toward normal control values following chelation. CaNa2EDTA chelation ameliorates the alterations linked with Pb mediated oxidative stress, indicating possible benefits in reducing health risks associated with increased oxidative damage in lead exposed populations. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  6. IR, UV-Vis, magnetic and thermal characterization of chelates of some catecholamines and 4-aminoantipyrine with Fe(III) and Cu(II)

    Science.gov (United States)

    Mohamed, Gehad G.; Zayed, M. A.; El-Dien, F. A. Nour; El-Nahas, Reham G.

    2004-07-01

    The dopamine derivatives participate in the regulation of wide variety of physiological functions in the human body and in medication life. Increase and/or decrease in the concentration of dopamine in human body reflect an indication for diseases such as Schizophrenia and/or Parkinson diseases. α-Methyldopa (α-MD) in tablets is used in medication of hypertension. The Fe(III) and Cu(II) chelates with coupled products of adrenaline hydrogen tartarate (AHT), levodopa (LD), α-MD and carbidopa (CD) with 4-aminoantipyrine (4-AAP) are prepared and characterized. Different physico-chemical methods like IR, magnetic and UV-Vis spectra are used to investigate the structure of these chelates. Fe(III) form 1:2 (M:catecholamines) chelates while Cu(II) form 1:1 chelates. Catecholamines behave as a bidentate mono- or dibasic ligands in binding to the metal ions. IR spectra show that the catecholamines are coordinated to the metal ions in a bidentate manner with O,O donor sites of the phenolic - OH. Magnetic moment measurements reveal the presence of Fe(III) chelates in octahedral geometry while the Cu(II) chelates are square planar. The thermal decomposition of Fe(III) and Cu(II) complexes is studied using thermogravimetric (TGA) and differential thermal analysis (DTA) techniques. The water molecules are removed in the first step followed immediately by decomposition of the ligand molecules. The activation thermodynamic parameters, such as, energy of activation, enthalpy, entropy and free energy change of the complexes are evaluated and the relative thermal stability of the complexes are discussed.

  7. Manganese(II) chelate contrast media

    International Nuclear Information System (INIS)

    Rocklage, S.M.; Quay, S.C.

    1994-01-01

    New chelate forming compounds for use as contrast media in NMR imaging are described. Especially mentioned are manganese(II) ion chelates of N,N' dipyridoxaldiamine, N,N' diacetic acid, and salts and esters thereof. 1 fig

  8. A study on the photocatalytic reaction of the metals and organics

    International Nuclear Information System (INIS)

    Nah, Jung Won; Cho, Yung Hyun; Sung, Ki Woong; Kim, Yong Ik; Hong, Kwang Bum; Kang, Heui Suk; Koo, Je Hyoo; Kim, Kwang Lak; Paek, Seung Woo; Lee, Han Soo; Chung, Heung Suk; Chung, Yong Won

    1994-12-01

    Lead metal ion was selected as the model one in the experiment for photo catalytic reaction containing EDTA. Disappearance rate of lead ion in solution was analyzed with control variables of initial pH value, concentration of chelating agent, and concentration ratio of metal ion and chelating agent. 31 figs, 6 tabs, 67 refs. (Author)

  9. A study on the photocatalytic reaction of the metals and organics

    Energy Technology Data Exchange (ETDEWEB)

    Nah, Jung Won; Cho, Yung Hyun; Sung, Ki Woong; Kim, Yong Ik; Hong, Kwang Bum; Kang, Heui Suk; Koo, Je Hyoo; Kim, Kwang Lak; Paek, Seung Woo; Lee, Han Soo; Chung, Heung Suk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Chung, Yong Won [In Hah Univ., Inchun (Korea, Republic of)

    1994-12-01

    Lead metal ion was selected as the model one in the experiment for photo catalytic reaction containing EDTA. Disappearance rate of lead ion in solution was analyzed with control variables of initial pH value, concentration of chelating agent, and concentration ratio of metal ion and chelating agent. 31 figs, 6 tabs, 67 refs. (Author).

  10. Decomposition rates of radiopharmaceutical indium chelates in serum

    International Nuclear Information System (INIS)

    Yeh, S.M.; Meares, C.F.; Goodwin, D.A.

    1979-01-01

    The rates at which six small aminopolycarboxylate chelates of trivalent 111 In and three protein-bound chelates of 111 In deliver indium to the serum protein transferrin have been studied in sterile human serum at pH 7.3, 37 deg C. Sterically hindered chelates containing a substituent on an ethylene carbon of EDTA decompose with rates in the range 0.03 to 0.11% per day - one to two orders of magnitude slower than other chelates. Only small differences are observed between rates of decomposition for low-molecular-weight chelates and for protein-bound chelates having analogous structures. (author)

  11. Comparison of Adsorption of Phenol O-O and N-O Chelating Collectors at the Malachite/Water Interface in Flotation

    Directory of Open Access Journals (Sweden)

    Zhili Li

    2017-02-01

    Full Text Available To separate one base metal mineral from another by flotation, it is indispensable to identify chemical reagents that specifically interact with the surface metal sites of one mineral or a group of minerals. This work studies the interactions of chelating collectors which offer the best potential for collecting abilities and mineral specificity with a typical refractory oxide mineral (malachite. Zeta potential, adsorption and Fourier transform infrared (FTIR measurements are applied to differentiate the interactions of salicylaldoxime and salicyl hydroxamate on the malachite surface. Salicylaldoxime and salicyl hydroxamate are of molecular structures that resemble each other, but with different bond distances in the ligand atoms which result in their unusual adsorption behavior and collecting ability. Thus, the flotation of malachite behaves differently with the two chelating collectors. This study might provide useful clues for designing novel collectors in base metal oxide flotations.

  12. 2013 Gordon Research Conference on metals in biology and seminar on bioinorganic chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Rosenzweig, Amy C. [Northwestern Univ., Evanston, IL (United States)

    2013-01-25

    Typical topics for lectures and posters include: biochemical and biophysical characterization of new metal containing proteins, enzymes, nucleic acids, factors, and chelators from all forms of life; synthesis, detailed characterization, and reaction chemistry of biomimetic compounds; novel crystal and solution structures of biological molecules and synthetic metal-chelates; discussions of the roles that metals play in medicine, maintenance of the environment, and biogeochemical processes; metal homeostasis; application of theory and computations to the structure and mechanism of metal-containing biological systems; and novel applications of spectroscopy to metals in biological systems.

  13. Labeling of antibodies with a 67Ga-phenolic aminocarboxylic acid chelate. Pt. 1

    International Nuclear Information System (INIS)

    Schuhmacher, J.; Matys, R.; Hauser, H.; Maier-Borst, W.; Matzku, S.

    1986-01-01

    As a chelating agent for labeling antibodies (Abs) with metallic radionuclides, a propionic acid substituted ethylenediamine N, N'-di-[(o-hydroxyphenyl) acetic acid] (P-EDDHA), which tighly complexes 67 Ga, was synthetized. The 67 Ga-P-EDDHA chelate was coupled in aqueous solution to IgG at a molar ratio of 1:1 via carbodiimide. The average coupling yield was 15%. A specific activity of 4 mCi/mg IgG could be obtained with commercially supplied 67 Ga. In vitro stability was evaluated in human serum at 37 0 C and showed a half-life of about 120 h for the release of 67 Ga from the labeled Ab during the initial phase of incubation. This in vitro halflife is similar to that measured for 111 In-DTPA labeled Abs. Because of the high stability of the 67 Ga-P-EDDHA chelate, the in vivo formation of radioactive lebeled transferrin by transchelation, as described for 111 In-DTPA labeled Abs, should, however, be reduced by this labeling technique. (orig.)

  14. Chelate-assisted phytoextraction: effect of EDTA and EDDS on copper uptake by Brassica napus L.

    Directory of Open Access Journals (Sweden)

    TIJANA M. ZEREMSKI-ŠKORIĆ

    2010-09-01

    Full Text Available Chelate-assisted phytoextraction is proposed as an effective approach for the removal of heavy metals from contaminated soil through the use of high biomass plants. The aim of the present study was to compare the efficiency of the two chelators: EDTA and biodegradable EDDS in enhancing Cu uptake and translocation by Brassica napus L. grown on moderately contaminated soil and treated with increasing concentrations of EDTA or EDDS. Increasing amounts of EDDS caused serious growth suppression of B. napus and an increase in shoot metal concentrations. Growth suppression limited the actual amount of phytoextracted Cu at high concentrations of EDDS. The maximum amount of extracted Cu was achieved by the application of 8.0 and 4.0+4.0 mmol kg-1 EDDS. The shoot Cu concentrations after EDTA application were much lower than with EDDS at the same doses. According to these experiments, EDTA does not appear to be an efficient amendment if Cu phytoextraction with B. napus is considered but EDDS is.

  15. From chelating precursors to La0.05Sr0.95CoO3-y oxide

    International Nuclear Information System (INIS)

    Hong, L.; Guo, F.; Lin, J.

    1999-01-01

    Several La 0.05 Sr 0.95 CoO 3-y (LSCO-95) powders were synthesized by means of a chelated complex-based precursor approach, which involved pyrolysis of chelating precursors and subsequent calcination of the resulting oxides. This paper focuses on the coordination effects of the precursors on the formation of the crystalline phases of the LSCO-95 oxide, showing that when the precursor is composed of EDTA-metal complexes, the perovskite-type oxide LSCO-95, an electronic-ionic mixed conducting ceramic material, can be achieved. In contrast, those LSCO-95 powders obtained initially from the pyrolysis of the precursors containing other coordination ligands possess only the undesirable hexagonal structure

  16. Relationship among chelator adherence, change in chelators, and quality of life in thalassemia.

    Science.gov (United States)

    Trachtenberg, Felicia L; Gerstenberger, Eric; Xu, Yan; Mednick, Lauren; Sobota, Amy; Ware, Hannah; Thompson, Alexis A; Neufeld, Ellis J; Yamashita, Robert

    2014-10-01

    Thalassemia, a chronic blood disease, necessitates life-long adherence to blood transfusions and chelation therapy to reduce iron overload. We examine stability of health-related quality of life (HRQOL) in thalassemia and adherence to chelation therapy over time, especially after changes in chelator choice. Thalassemia Longitudinal Cohort participants in the USA, UK, and Canada completed the SF-36v2 (ages 14+) and the PF-28 CHQ (parents of children health status) at baseline who made a single change in chelator, but declined among participants with multiple changes and/or high iron burden (worse health status). Mental health improved among participants with lower iron burden, but iron overload was negatively associated with social functioning. Adherence did not significantly change over follow-up except for an increase after a change from deferoxamine (DFO) infusion to oral deferasirox (p = 0.03). Predictors of lower adherence for adults/adolescents at follow-up included side effects, smoking, younger age, problems preparing DFO, increased number of days per week DFO prescribed, and lower physical quality of life . Strategies to balance medical needs with family, work, and personal life may assist in adherence.

  17. Mechanisms of Fe biofortification and mitigation of Cd accumulation in rice (Oryza sativa L.) grown hydroponically with Fe chelate fertilization.

    Science.gov (United States)

    Chen, Zhe; Tang, Ye-Tao; Zhou, Can; Xie, Shu-Ting; Xiao, Shi; Baker, Alan J M; Qiu, Rong-Liang

    2017-05-01

    Cadmium contaminated rice from China has become a global food safety issue. Some research has suggested that chelate addition to substrates can affect metal speciation and plant metal content. We investigated the mitigation of Cd accumulation in hydroponically-grown rice supplied with EDTANa 2 Fe(II) or EDDHAFe(III). A japonica rice variety (Nipponbare) was grown in modified Kimura B solution containing three concentrations (0, 10, 100 μΜ) of the iron chelates EDTANa 2 Fe(II) or EDDHAFe(III) and 1 μΜ Cd. Metal speciation in solution was simulated by Geochem-EZ; growth and photosynthetic efficiency of rice were evaluated, and accumulation of Cd and Fe in plant parts was determined. Net Cd fluxes in the meristematic zone, growth zone, and maturation zone of roots were monitored by a non-invasive micro-test technology. Expression of Fe- and Cd-related genes in Fe-sufficient or Fe-deficient roots and leaves were studied by QRT-PCR. Compared to Fe deficiency, a sufficient or excess supply of Fe chelates significantly enhanced rice growth by elevating photosynthetic efficiency. Both Fe chelates increased the Fe content and decreased the Cd content of rice organs, except for the Cd content of roots treated with excess EDDHAFe(III). Compared to EDDHAFe(III), EDTANa 2 Fe(II) exhibited better mitigation of Cd accumulation in rice by generating the EDTANa 2 Cd complex in solution, decreasing net Cd influx and increasing net Cd efflux in root micro-zones. Application of EDTANa 2 Fe(II) and EDDHAFe(III) also reduced Cd accumulation in rice by inhibiting expression of genes involved in transport of Fe and Cd in the xylem and phloem. The 'win-win' situation of Fe biofortification and Cd mitigation in rice was achieved by application of Fe chelates. Root-to-stem xylem transport of Cd and redistribution of Cd in leaves by phloem transport can be regulated in rice through the use of Fe chelates that influence Fe availability and Fe-related gene expression. Fe fertilization

  18. Direct nanoimprint lithography of Al2O3 using a chelated monomer-based precursor

    International Nuclear Information System (INIS)

    Ganesan, Ramakrishnan; Dinachali, Saman Safari; Lim, Su Hui; Saifullah, M S M; He, Chaobin; Low, Hong Yee; Chong, Wee Tit; Lim, Andrew H H; Yong, Jin Jie; Thian, Eng San

    2012-01-01

    Nanostructuring of Al 2 O 3 is predominantly achieved by the anodization of aluminum film and is limited to obtaining porous anodized aluminum oxide (AAO). One of the main restrictions in developing approaches for direct fabrication of various types of Al 2 O 3 patterns, such as lines, pillars, holes, etc, is the lack of a processable aluminum-containing resist. In this paper, we demonstrate a stable precursor prepared by reacting aluminum tri-sec-butoxide with 2-(methacryloyloxy)ethyl acetoacetate, a chelating monomer, which can be used for large area direct nanoimprint lithography of Al 2 O 3 . Chelation in the precursor makes it stable against hydrolysis whilst the presence of a reactive methacrylate group renders it polymerizable. The precursor was mixed with a cross-linker and their in situ thermal free-radical co-polymerization during nanoimprinting rigidly shaped the patterns, trapped the metal atoms, reduced the surface energy and strengthened the structures, thereby giving a ∼100% yield after demolding. The imprinted structures were heat-treated, leading to the loss of organics and their subsequent shrinkage. Amorphous Al 2 O 3 patterns with line-widths as small as 17 nm were obtained. Our process utilizes the advantages of sol–gel and methacrylate routes for imprinting and at the same time alleviates the disadvantages associated with both these methods. With these benefits, the chelating monomer route may be the harbinger of the universal scheme for direct nanoimprinting of metal oxides. (paper)

  19. Demetalation of Fe, Mn, and Cu chelates and complexes: application to the NMR analysis of micronutrient fertilizers.

    Science.gov (United States)

    López-Rayo, Sandra; Lucena, Juan J; Laghi, Luca; Cremonini, Mauro A

    2011-12-28

    The application of nuclear magnetic resonance (NMR) for the quality control of fertilizers based on Fe(3+), Mn(2+), and Cu(2+) chelates and complexes is precluded by the strong paramagnetism of metals. Recently, a method based on the use of ferrocyanide has been described to remove iron from commercial iron chelates based on the o,o-EDDHA [ethylenediamine-N,N'bis(2-hydroxyphenylacetic)acid] chelating agent for their analysis and quantification by NMR. The present work extended that procedure to other paramagnetic ions, manganese and copper, and other chelating, EDTA (ethylenediaminetetraacetic acid), IDHA [N-(1,2-dicarboxyethyl)-d,l-aspartic acid], and complexing agents, gluconate and heptagluconate. Results showed that the removal of the paramagnetic ions was complete, allowing us to obtain (1)H NMR spectra characterized by narrow peaks. The quantification of the ligands by NMR and high-performance liquid chromatography showed that their complete recovery was granted. The NMR analysis enabled detection and quantification of unknown impurities without the need of pure compounds as internal standards.

  20. Improving the efficiency of phytoremediation using electrically charged plant and chelating agents.

    Science.gov (United States)

    Tahmasbian, Iman; Safari Sinegani, Ali Akbar

    2016-02-01

    The low efficiency of phytoremediation is a considerable problem that limits the application of this environmentally friendly method on heavy metal-polluted soils. The combination of chelate-assisted phytoextraction and electrokinetic remediation could offer new opportunities to improve the effectiveness of phytoextraction. The current experiment aims to investigate the effects of electrical fields and chelating agents on phytoremediation efficiency. In a pot experiment using mine soil, poultry manure extract (PME), cow manure extract (CME), and ethylenediaminetetraacetic acid (EDTA) were applied to soil as chelating agents (2 g kg(-1)) at the beginning of the flowering stage. A week later, Helianthus annuus (sunflower) was negatively charged by inserting a stainless steel needle with 10 and 30 V DC electricity in the lowest part of the stems for 1 h each day for a 14-day period. At the end of the experiment, the shoot and root dry weight, lead (Pb) concentration in plant organs, translocation factor (TF), metal uptake index (UI), and soil available Pb (diethylene triamine pentaacetic acid (DTPA) extractable) were detected. Results indicated that the application of electrical fields had no significant impact on the shoot and root dry weights, while Pb concentration and UI increased in the 10-V EDTA treatment by 500 % compared to control. There was no significant difference between UI in 30- and 10-V EDTA treatments. Soil available Pb significantly increased in the 30-V treated soil. A positive correlation was observed between the available Pb in soil near the root and Pb concentration in shoot, its TF, and UI. In conclusion, a negatively charged plant along with the application of EDTA significantly increased the phytoremediation efficiency.

  1. Effects of Application of NTA and EDTA on Accumulation of Soil Heavy Metals in Chrysanthemum

    Science.gov (United States)

    Bai, Weiyang

    2018-02-01

    In order to find out the effect of non-bio chelating agent EDTA and bio-chelating agent NTA on soil heavy metal pollution, the effects of different ratio of chelating agent NTA and EDTA on soil heavy metals (Pb, Cu and Cd ), the effects of chelating on content of chlorophyll and vitamin C and the degree of soil nutrient loss were evaluated. The results showed: that the contents of Pb and Cd were the highest in the roots of Chrysanthemum in the treatment (EDTA / NTA = 2: 1). The treatment (EDTA / NTA = 1: 1) was the best chelating agent ratio for the synergistic effect, which can significantly promoted the Chrysanthemum on heavy metal Cu uptake and transport to aboveground. Chrysanthemum were inhibited by all chelating agents treatments, while the content of chlorophyll and vitamin C of the Chrysanthemum physiological indexes were reduced. In the treatment (EDTA = 1), chlorophyll SPAD, vitamin C content reached a minimum of 36 and 38mg · 100g-1, respectively. The nutrient element TN in the leachate were gradually decreased with the time, and the tenth day was significantly lower than the leaching rate of the first day (p treatment (EDTA = 1) >treatment (EDTA / NTA = 2: 1) >treatment (EDTA / NTA = 1: 2)> treatment (NTA = 1). Treatment (EDTA / NTA = 2: 1) was recommended for the chelating agent ratio with the better physiological parameters, the more heavy metal extraction and the less nitrogen and phosphorus loss

  2. Comments on chelation therapy

    International Nuclear Information System (INIS)

    Wrenn, M.E.

    1981-01-01

    The primary purpose of actinide chelation is to decrease the risk from radiation-induced cancer. While occupational exposures in the past have mainly involved low specific activity 239 Pu, future exposures will increasingly involve high specific activity plutonium, americium, and curium - all of which clear more rapidly from the lung. This will tend to shift the cancer risk from lung to bone and liver. Although therapy with Ca- or Zn-DTPA rapidly removes 241 Am from the canine, the sub-human primate, and the human liver, improved methods for removal from bone and lung are needed. DTPA can remove 241 Am more easily from the growing skeleton of a child than from the mature skeleton of an adult. Investigators at Karlsruhe are developing chelation agents for oral administration and are investigating the reduction in local dose to bone resulting from chelation therapy

  3. Use of complexones solutions in liquid carbon dioxide for cleaning of materials contaminated with heavy and radioactive metals

    International Nuclear Information System (INIS)

    Shadrin, A.Yu.; Kamachev, V.A.; Kiseleva, R.N.; Murzin, A.A.; Shafikov, D.N.; Bondin, V.V.; Efremov, I.V.; Kovalev, D.N.; Podoinitsyn, S.V.

    2003-01-01

    I n this paper liquid carbon dioxide (pressure 50-70 atm) was used for decontamination. The performed experiments on removal of cobalt, nickel, uranium and americium nitrates and carbonates by different solutions have shown that the solutions of such complexing agents as hexafluoroacetylacetone (HFA), tributylphosphate (TBP), di-2-ethylhexylphosphoric acid (D2EHPA) in liquid CO 2 can be used for purification of pulps, metals, paper and fabrics. Liquid CO 2 is high viscosity of the medium and hence low diffusion coefficients and long duration of the processes. It is known that 20 minutes are sufficient to attain equilibrium in supercritical CO 2 medium on metal removal by HFA solutions. During the experiments it was established that with the use of liquid CO 2 the keeping time should be increased to 40 min, which is acceptable from the standpoint of technical feasibility of decontamination processes in these solutions. Experiments on really contaminated samples of pulps, metals and fabrics have confirmed that the decontamination coefficients of 30-100 can be easily obtained by 2-3 fold material treatment operations. The secondary waste volume therewith is less by a factor of 20-200 than that of traditional techniques. (authors)

  4. Thermodynamic stability and relaxation studies of small, triaza-macrocyclic Mn(II) chelates.

    Science.gov (United States)

    de Sá, Arsénio; Bonnet, Célia S; Geraldes, Carlos F G C; Tóth, Éva; Ferreira, Paula M T; André, João P

    2013-04-07

    Due to its favorable relaxometric properties, Mn(2+) is an appealing metal ion for magnetic resonance imaging (MRI) contrast agents. This paper reports the synthesis and characterization of three new triazadicarboxylate-type ligands and their Mn(2+) chelates (NODAHep, 1,4,7-triazacyclononane-1,4-diacetate-7-heptanil; NODABA, 1,4,7-triazacyclononane-1,4-diacetate-7-benzoic acid; and NODAHA, 1,4,7-triazacyclononane-1,4-diacetate-7-hexanoic acid). The protonation constants of the ligands and the stability constants of the chelates formed with Mn(2+) and the endogenous Zn(2+) ion have been determined by potentiometry. In overall, the thermodynamic stability of the chelates is lower than that of the corresponding NOTA analogues (NOTA = 1,4,7-triazacyclononane-1,4,7-triacetate), consistent with the decreased number of coordinating carboxylate groups. Variable temperature (1)H NMRD and (17)O NMR measurements have been performed on the paramagnetic chelates to provide information on the water exchange rates and the rotational dynamics. The values of the (17)O chemical shifts are consistent with the presence of one water molecule in the first coordination sphere of Mn(2+). The three complexes are in the slow to intermediate regime for the water exchange rate, and they all display relatively high rotational correlation times, which explain the relaxivity values between 4.7 and 5.8 mM(-1) s(-1) (20 MHz and 298 K). These relaxivities are higher than expected for Mn(2+) chelates of such size and comparable to those of small monohydrated Gd(3+) complexes. The amphiphilic [Mn(NODAHep)] forms micelles above 22 mM (its critical micellar concentration was determined by relaxometry and fluorescence), and interacts with HSA via its alkylic carbon chain providing a 60% relaxivity increase at 20 MHz due to a longer tumbling time.

  5. Curcumin Inhibits Growth of Saccharomyces cerevisiae through Iron Chelation ▿ ††

    OpenAIRE

    Minear, Steven; O'Donnell, Allyson F.; Ballew, Anna; Giaever, Guri; Nislow, Corey; Stearns, Tim; Cyert, Martha S.

    2011-01-01

    Curcumin, a polyphenol derived from turmeric, is an ancient therapeutic used in India for centuries to treat a wide array of ailments. Interest in curcumin has increased recently, with ongoing clinical trials exploring curcumin as an anticancer therapy and as a protectant against neurodegenerative diseases. In vitro, curcumin chelates metal ions. However, although diverse physiological effects have been documented for this compound, curcumin's mechanism of action on mammalian cells remains un...

  6. EXTRACTION, RECOVERY, AND BIOSTABILITY OF EDTA FOR REMEDIATION OF HEAVY METAL-CONTAMINATED SOIL. (R825549C052)

    Science.gov (United States)

    Chelation removal of heavy metals from contaminated soil is seen as a viable remediation technique. A useful chelating agent should be strong, reusable, and biostable during metal extraction and recovery operations. This work tested the extraction, recovery, and biostability o...

  7. Overview of current chelation practices

    Directory of Open Access Journals (Sweden)

    Y. Aydinok

    2011-12-01

    Full Text Available Deferoxamine (DFO is reference standard therapy for transfusional iron overload since the 1980s. Although it is a highly effective iron chelator, the compliance problem to subcutaneous administration of DFO remains as the major problem. The oral chelator Deferiprone (DFP has no marketing licence in North America, however, it has been licensed in India since 1994 and the European Union (EU granted marketing approval for DFP in 1999, specifically for patients with thalassemia major when DFO is inadequate, intolerable or unacceptable. There are still limited data available on the use of DFP in children between 6 and 10 years of age, and no data on DFP use in children under 6 years of age. Subsequently the oral chelator Deferasirox (DFX was approved by FDA and EMA for the treatment of patients with transfusional iron overload -older than 2 years of age- as first line therapy, in 2005 and 2006 respectively. The primary objective of iron chelation is to maintain body iron at safe levels at all times but once iron is accumulated, the objective of iron chelation is to reduce tissue iron to safe levels which is a slow process. The chelation regimen, dose and frequency of administration, of the chelator(s are mainly determined based on body iron burden, presence of myocardial iron and the transfusional iron loading rate. A proper monitoring of chelation is of importance for measuring the response rate to a particular regimen and providing dose adjustments to enhance chelation efficacy and to avoid toxicity. Efficacy of a chelation regimen may exhibit individual variability resulting from factors such as absorbtion and metabolism of the chelator. Tolerability and compliance are also individual variables effecting the response to chelation. Understanding of advantages and limitations of chelators, accurately determining chelation needs of patients with iron overload and designing individualized chelation regimens with less toxicity but optimum efficacy

  8. Comparison of the ability of organic acids and EDTA to enhance the phytoextraction of metals from a multi-metal contaminated soil.

    Science.gov (United States)

    Kim, Sung-Hyun; Lee, In-Sook

    2010-02-01

    Chelates have been shown to enhance the phytoextraction of metal from contaminated soil. In this study, we evaluated the ability of chelates to enhance the phytoextraction of metals by barnyard grass (Echinochloa crus-galli) from soils contaminated with multiple metals. The results revealed that EDTA increased the ability of barnyard grass to take up Cd, Cu and Pb, but that it resulted in increased soil leaching. Conversely, citric acid induced the removal of Cd, Cu and Pb from soil without increasing the risk of leaching. Furthermore, E.crus-galli showed no signs of phytotoxicity in response to treatment with citric acid, whereas its shoot growth decreased in response to treatment with EDTA (p acid is a good agent for the enhancement of the phytoextraction of metals.

  9. Chelation in root canal therapy reconsidered.

    Science.gov (United States)

    Zehnder, Matthias; Schmidlin, Patrick; Sener, Beatrice; Waltimo, Tuomas

    2005-11-01

    The aim of this study was to assess interactions of EDTA and citric acid (CA) with sodium hypochlorite (NaOCl), the indispensable endodontic irrigant. Other chelators were simultaneously evaluated as possible alternatives: sodium triphosphate (STP), amino tris methylenephosphonic acid (ATMA), and 1- hydroxyethylidene-1, 1-bisphosphonate (HEBP). Available chlorine was titrated in chelator-NaOCl solutions. All chelators other than HEBP and STP caused an almost complete, immediate loss of available chlorine in solution. Atomic absorbtion spectrometry and SEM evaluation of root canal walls of instrumented teeth indicated that NaOCl had no negative effect on calcium-complexing ability of chelators. STP was too weak a complexing agent to warrant further studies. Finally, CA-, EDTA-, and HEBP-NaOCl mixtures were evaluated for their antimicrobial capacity. Again, EDTA and CA negatively interfered with NaOCl, while HEBP did not.

  10. The Alchemist’s Approach to Metal Poisoning: Transforming the Metal Burden

    Directory of Open Access Journals (Sweden)

    Wayne Briner

    2014-06-01

    Full Text Available Metal poisoning is a global problem with humans being exposed to a wide range of metals in varying doses and varying time frames. Traditionally, treatment involves removal of the toxic source or chelation therapy. An intermediate approach is needed. This review outlines the argument for the use of essential metal supplementation as a strategy to induce metallothionein expression and displace the toxic metal from important biological systems, improving the metal burden of the patient. Specific recommendations are given for supplementation with calcium, zinc and vitamin E as a broad strategy to improve the status of those exposed to toxic metals.

  11. Biological behaviour of some 67Ga and 64Cu chelates

    International Nuclear Information System (INIS)

    Leonovicova, T.; Angelis, B.; Cifka, J.; Cifkova, I.

    1984-01-01

    Chelates of 67 Ga and 64 Cu with iminodiacetic acid (IDA) and its two phenyl derivatives as well as with nitrilotriacetic acid (NTA) and benzylnitrilotriacetic acid (BNTA) were prepared. All the chelates were found to be negatively charged. A study of the biological distribution of these chelates in rats during time intervals of 3 to 180 min showed that the chelate of 67 Ga with IDA substituted at a phenyl by a hydrophobic substituent is excreted by the kidneys into the urine at a much higher rate than the IDA chelate of 67 Ga. The excretion of NTA and BNTA chelates of 67 Ga is the opposite. Blood clearance of 64 Cu chelates is more rapid than that of 67 Ga chelates. Chelates of 64 Cu accumulate in the liver and with the bile are slowly excreted into the intestines, urinary excretion is negligible. (author)

  12. Effectiveness of DTPA Chelate on Cd Availability in Soils Treated with Sewage Sludge

    Directory of Open Access Journals (Sweden)

    Pegah Houshyar

    2017-09-01

    Full Text Available Application of sewage sludge as a fertilizer on farmlands is a common practice in most countries. Although the practice may play a positive role in plant performance, the organic amendments introduced may increase the soil heavy metals content. This study was conducted in Arak, Iran, to investigate the effectiveness of DTPA chelate on corn Cd availability in a sewage sludge treated soil. The treatments consisted of sewage sludge (0, 15, and 30 t ha-1 polluted with cadmium applied at 0, 5, 10, and 15 mg kg-1 as well as DTPA applied at 0 and 1.5 mmol kg-1 soil. Corn plants were then grown in the soil in each treatmnent and, on day 60, the physic-chemical characteristics and Cd quantities were measured ion both the corn plants and soil samples. Application of 1.5 m mol of DTPA chelate in soil contaminated with 5 mg Cd led to a significant increase in the soil available Cd content. It was also observed that application of DTPA chelate to soils containing 30 t ha-1 of sewage sludge polluted with 10 mg Cd increased root and shoot Cd concentrations by 17 and 25%, respectively. Results indicated the effectiveness of DTPA chelate in reducing Cd phytoremediation with increasing sewage sludge loading rate. This was evidenced by the lowest phytoremediation effectiveness observed for the treatment with the greatest sewage sludge loading (30 t ha-1 and the lowest cadmium pollution (5 mg Cd.

  13. TEM and SEM observation of uranium induced renal necrosis and the result of chelates treatment on rats

    International Nuclear Information System (INIS)

    Sun Shiquan; Li Baoxing; Lai Chixiang; You Zhanyun

    1987-01-01

    The TEM (transmission electron microscope) and SEM (scanning electron microscope) observation of uranium induced renal necrosis and the result of chelates treatment on rats are reported. Ultrastructural changes in kidney related with the impairment of intracellular fluid transportation can be found after acute uranium intoxication in rats, such as: condensation and swelling of mitochondria, matrix edema, dilatation of intercellular space, disappearance of basal folds, thickening of basal web, intensification of basal lamina of the proximal convoluted tubule epithelium cells, and foot processes swelling, diminishing of endothelium fenestrae of the renal glomerulus. Heavy metal chelates DTPA and H-73-10 treatment may result in intracellular fluid accumulation and condensed grannule formation in lysosome. Treatment with these chelates in the critical stage of uranium intoxication may accelerate the necrosis instead of diminishing. This may be related to the augment of the load of lysosome and intracellular system of fluid transportation

  14. Synthesis and characterization of radiation grafted films for removal of arsenic and some heavy metals from contaminated water

    International Nuclear Information System (INIS)

    Chowdhury, M.N.K.; Khan, M.W.; Mina, M.F.; Beg, M.D.H.; Khan, Maksudur R.; Alam, A.K.M.M.

    2012-01-01

    Grafting of styrene/maleic anhydride and methyl methacrylate/maleic anhydride binary monomers onto the low density polyethylene film was performed using the γ-ray irradiation technique. Then, the synthesized grafted films were treated with different ammonia derivatives for developing chelating functionalization. These chelating products were characterized by the gravimetric method as well as by the Fourier transformed infrared spectroscopic method, and were used for removal of arsenic and some heavy metals from aqueous solutions. The optimum absorbed dose of 30 kGy reveals the graft yielding of about 325% in the films. Uptake of arsenic and some heavy-metal ions (Cr(III), Mn(II), Fe(III), Ni(II), Cu(II) and Pb(II)) from contaminated water by the chelating functionalized films (CFF) was examined by an atomic absorption spectrophotometer. The maximum arsenic removal capacity of 5062 mg/kg has been observed for the film treated with hydroxylamine hydrochloride. The CFF prepared by semicarbazide and thiol analogs show affinity toward the metal ions with an order: Cu(II)>Fe(III)>Mn(II) etc. The results obtained from this study indicate that the functionalized films show good chelating and ion-exchange property for metal ions. - Highlights: ► Optimization of radiation dose for grafting reaction of polyethylene with binary monomers. ► Chelating functionalization of grafted film with various amine compounds. ► Characterization of both grafted and chelating functionalized films. ► Proposed mechanism for both grafting and chelating functionalization reaction. ► Application of the synthesized films for the removal of arsenic and some heavy metals from contaminated water.

  15. Photocatalyzed removal of lead ion from lead-chelator solution

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young Hyun; Na, Jung Won; Sung, Ki Woung [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1994-07-01

    The present study was undertaken to examine the influence of such chelating agents on the ease and speed of photocatalyzed metal removal and deposition. With excess EDTA, the free EDTA competes with Pb for oxidation, and at a ten fold excess, no lead oxidation (hence removal) occurs. With insufficient EDTA, the corresponding initial concentration of Pb-EDTA is decreased; after its destruction, the remaining Pb{sup 2+} is removed more slowly, at rates found with lead nitrate solution. The net result is that the maximum rate of lead deposition occurs at the stoichiometric ratio of 1:1 EDTA : Pb{sup 2+}.

  16. ROLE OF SOME CHEMICAL MATERIALS ON THE PHYTO-EXTRACTION OF HEAVY METALS FROM CONTAMINATED SOILS WITH SUNFLOWER PLANTS (HELIANTHUS ANNUUS)

    International Nuclear Information System (INIS)

    ABD EL-BARY, S.A.; EL-NAKA, E.A.; RIZK, M.A.; LOTFY, S.M.

    2009-01-01

    Chelation and complexation of heavy metals were evaluated as practical ways to solubilize, detoxify and enhance heavy metals accumulation by plants. Sunflower (Helianthus annuus) was selected as potential heavy metals accumulator for metals phyto-extraction in two selected soils (clayey and sandy). To enhance metals phyto-extraction, ammonium nitrate and organic chelates such as EDTA and citric acid were added to soils at the rates from 0 to 20 mmol/kg soil as extracting solutions and applied to the soil by mixing thoroughly before planting. Dry matter production and metals concentrations in shoots and roots and soil pH were measured after 60 days.Plant dry matter production and metals accumulation were varied with soil contamination, chelate / organic acid form and rate, and soil type. The highest metals concentration was obtained in plants grown on clayey soil, however, the lowest content was observed in case of sandy soil. Addition of citric acid increased metals accumulation and translocation to the shoots significantly. Addition of 20 mmol/kg of citric acid to clayey soils increased metals concentration in shoots several folds of magnitude, but addition of ammonium nitrate had little effect on metal translocation to shoots. Citric acid was the most effective chelate in plant accumulation of tested metals.

  17. Chelate-assisted phytoextraction of lead from contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, E.M.; Sims, J.T.; Cunningham, S.D.; Huang, J.W.; Berti, W.R.

    1999-12-01

    Phytoextraction, a remediation strategy for lead (Pb)-contaminated soils that removes soil Pb through plant uptake and harvest, may be enhanced by use of synthetic chelates. The authors evaluated Pb desorption from four contaminated soils by seven chelates (CDTA, DTPA, EDDHA, EFTA, HEDTA, HEIDA, and NTA) at three rates. The three most effective chelates (CDTA, DTPA, and HEDTA) were used in greenhouse studies with an uncontaminated soil and a Pb-contaminated soil to determine the effect of chelate type and rate on growth, Pb uptake, and plant elemental composition. Lead desorption varied with chelate and soil and increased with chelate rate, averaging 948 mg Pb kg{sup {minus}1} at the 20 mmol kg{sup {minus}1} rate vs. 28 mg Pb kg{sup {minus}1} by the control. The general ranking of chelate effectiveness, based on total Pb desorbed, was HEDTA > CDTA > DTPA > EGTA > HEIDA > EDDHA {approximately} NTA. Plant uptake of Pb from the contaminated soil was enhanced by CDTA, DTPA, and HEDTA, but with even the most effective treatment (corn, high CDTA rate), the amount of Pb extracted by plants was rather low. Lead extractable by the Toxicity Characteristic Leaching Procedure (TCLP) was increased from 9 mg L{sup {minus}1} in the control to from 47 to 174 mg L{sup {minus}1} in soils treated with 20 mmol kg{sup {minus}1} CDTA or DTPA and chelates generally caused a shift in Pb from resistant to more soluble chemical fractions.

  18. Ce(III), Th(IV) and U(VI) chelates of alizarin viridine, alizarin heliotrope and alizarin maroon

    International Nuclear Information System (INIS)

    Idriss, K.A.; Issa, I.M.; Seleim, M.M.

    1977-01-01

    The complexes of 7,8-dihydroxy-1,4-di(2'-sulpho-4' methylanilino)-anthraquinone (alizarin viridine); 1,4-dihydroxy-2(2'-sulpho-4'-methylanilino)anthraquinone (alizarin heliotrope) and 3-amino-1,2-dihydroxyanthraquinone (alizarin maroon) with Ce(III), and U(VI) have been investigated using spectrophotometric and conductometric methods. The study revealed the formation of complexes having the metal: ligand ratios 1:1 and 1:2. The mean values of logβ (β being stability constant) for the different complexes are determined. The structure of the ligands in the solid chelates were studied by i.r. spectrophotmetry which showed that chelate formation takes place through the C=O and neighbouring OH group and leads to proton displacement. (author)

  19. Chelating ion exchange with macroreticular hydroxamic acid resins

    International Nuclear Information System (INIS)

    Phillips, R.J.

    1980-01-01

    The synthesis, reactions, and analytical applications of hydroxamic acids, including chelating resins with this functional group, are reviewed. A procedure for attaching N-phenyl hydroxamic acid groups to Amberlite XAD-4 is described. The extraction of 20 metal ions from 2 M hydrochloric acid by this resin is discussed. Conditions for the quantitative extraction and back-extraction of 9 ions are reported. Results are compared with work on solvent extraction with N-phenylbenzohydroxamic acid. Procedures for attaching N-methyl and N-unsubstituted hydroxamic acid groups to Amberlite XAD-4 are described. The N-phenyl, N-methyl, and N-unsubstituted hydroxamic acid resins are compared with respect to metal-ion complexation. The scope of applications for hydroxamic acid resins is investigated by studying the extraction of 19 metal ions as a function of pH. The resins are especially suitable for the extraction of zirconium(IV), titanium(IV), and uranium(IV) from strongly acidic solution. Aluminum(III) is separated from calcium and phosphate by extraction at pH 4. The use of the resins for the purification of reagents, concentration of trace constituents, and chromatographic separation is demonstrated

  20. Treating Lead Toxicity: Possibilities beyond Synthetic Chelation

    Directory of Open Access Journals (Sweden)

    Shambhavi Tannir

    2013-01-01

    Full Text Available Lead, a ubiquitous metal, is one of the most abundant elements present on earth. Its easy availability and cost effectiveness made it an extremely popular component in the industrial revolution. However, its hazardous health effects were not considered at the time. Over the last few decades, with the adverse effects of lead coming to the forefront, nations across the world have started to recognize and treat lead toxicity. The most reliable and used method until now has been chelation therapy. Recent research has suggested the use of natural products and sources to treat lead poisoning with minimal or no side effects. This review has tried to summarize a few of the natural products/sources being investigated by various groups.

  1. [Susceptibility of enterococci to natural and synthetic iron chelators].

    Science.gov (United States)

    Lisiecki, Paweł; Mikucki, Jerzy

    2002-01-01

    A total of 79 strains of enterococci belonging to 10 species were tested for susceptibility to natural and synthetic iron chelators. All strains produced siderophores. These enterococci were susceptible to three synthetic iron chelators only: 8-hydroxyquinoline, disodium versenate (EDTA) and o-phenanthroline. They were resistant to all other synthetic chelators: ethylenediamine-di(o-hydroxyphenylacetic acid) (EDDHA), nitrilotriacetate, 2,2'-bipiridyl, salicylic acid, 8-hydroxy-5-sulphonic acid and to all natural chelators: ovotransferrine, human apotransferrine, horse apoferritine, desferrioxamine B, ferrichrome and rhodotorulic acid. The relations between susceptibility/resistance, iron assimilation and structure and stability constants of iron chelators were discussed.

  2. Solubilidade, fracionamento e fitoextração de metais pesados após aplicação de agentes quelantes Solubility, phytoextraction and fractionation of heavy metals as a function of chelating agents applied to soil

    Directory of Open Access Journals (Sweden)

    Évio Eduardo Chaves de Melo

    2006-12-01

    Full Text Available A baixa biodegrabilidade de quelantes sintéticos usados para induzir a fitoextração resulta em alto risco ambiental pela possibilidade de lixiviação de metais pesados. Agentes quelantes naturais, mais rapidamente degradados no solo, podem ser uma alternativa para os quelantes sintéticos. O objetivo deste trabalho foi comparar a performance de ácidos orgânicos naturais (gálico, cítrico e oxálico com ácidos sintéticos (EDTA, DTPA e NTA na fitoextração induzida de metais. O solo foi contaminado com 500, 300 e 200 mg kg-1 de Pb, Zn e Cu, respectivamente, e cultivado com milho (Zea mays e mucuna preta (Stizolobium aterrimum. Os agentes quelantes, na dose de 10 mmol kg-1, foram aplicados no solo sete dias antes da coleta das plantas. Amostras do solo foram submetidas à extração com CaCl2 e fracionamento. Os teores dos metais na solução do solo foram também determinados. Os quelantes sintéticos EDTA, DTPA e NTA foram eficientes na solubilização dos metais pesados no solo. Dentre os ácidos orgânicos naturais, apenas o ácido cítrico foi eficiente na solubilização dos metais nas primeiras vinte e quatro horas após a sua aplicação. A distribuição dos metais entre as frações apresentou a seguinte ordem: Pb: matéria orgânica (MO > óxido de Fe amorfo (OxFeA > trocável (Tr > óxido de Fe cristalino (OxFeC; Cu: MO > Tr > OxFeC > OxFeA; e Zn: MO > Tr > OxFeC > OxFeA. De modo geral, a adição dos quelantes sintéticos provocou aumento nos teores trocáveis de Pb e Cu e redução nos teores de Pb, Cu e Zn nas frações óxidos de Fe amorfo e cristalino. O extrator CaCl2 0,01 mol L-1 pode ser utilizado para predição da concentração de Pb, Cu e Zn na solução do solo.The low biodegradability of synthetic chelating agents used for phytoextraction poses a great environmental risk due to the potential for metal leaching. Natural chelating agents can be an alternative to synthetic chelates due to their rapid biodegrability

  3. Mechanisms of chelation of heavy metals by chitosan

    International Nuclear Information System (INIS)

    Averbach, B.L.

    1980-01-01

    The concentration profiles of several heavy metal ions and anions have been measured in chitosan membranes immersed in dilute aqueous solutions. The shapes of the concentration curves for the metal ions is characteristic of a diffusion process in which the diffusion coefficient is a function of the concentration. The anion penetrates much more rapidly than the cation, however, and the concentration appears to be dependent on the reaction kinetics. We propose a mechanism whereby the metal ion bonds with the nitrogen in the functional amino group, with the bridging oxygen and with two hydroxyl groups in a neighboring glucose ring. The anion, on the other hand, bonds ionically to the metal-amino complex in order to neutralize the charge and to the protonated amino sites which have not reacted with the metal ion. In the case of uranium in sea water, it is probable that the uranium is present as a uranyl complex and that bonding with chitosan will occur by ionic bonding, that is, salt formation, rather than by covalent bonding to the amino groups. Uranyl complexes in dilute concentration will thus compete with chloride and the relative concentrations will be determined by the equilibrium constants. Work on the reaction between chitosan and dilute solutions of copper sulfate is reported. A mechanism for these reactions is postulated, and it is suggested that the same mechanism carries over to uranium in sea water. This suggests certain limitations on the process which should be explored if chitosan is to be used for this purpose

  4. Reducing the potential for migration of radioactive waste: Aqueous thermal degradation of the chelating agent disodium EDTA

    International Nuclear Information System (INIS)

    Boles, J.S.; Ritchie, K.; Crerar, D.A.

    1987-01-01

    Ethylenediaminetetraacetic acid (EDTA), a common component of cleaning solutions used for decontamination of radioactive equipment, has been associated with increased migration of radionuclides into local groundwaters at some radwaste disposal sites. It has been proposed that predisposal thermal degradation of EDTA-containing aqueous solutions may reduce the potential for chelate-enhanced mobilization of radionuclides at these sites. Aqueous thermal degradation experiments with disodium EDTA have shown that the compound degrades rapidly at 200 0 C with an activation energy of 114.3 +- 7.87 kJ/mol, and forms the decomposition product methyliminodiacetic acid (MIDA). A comparison of the values for stability constants of transition metal and actinide complexes with EDTA, MIDA, and two other reported degradation products, indicates that the chelating efficiency of the degradation products is 6 to 22 orders of magnitude lower than that of EDTA at 25 0 C. It is concluded that aqueous thermal degradation should significantly reduce the overall chelating efficiency of EDTA-containing solutions

  5. Immobilized poly-L-histidine for chelation of metal cations and metal oxyanions

    International Nuclear Information System (INIS)

    Malachowski, Lisa; Holcombe, James A.

    2003-01-01

    The biohomopolymer poly-L-histidine (PLHis) was immobilized onto controlled pore glass (CPG) and its metal binding capabilities evaluated through the use of a flow injection-flame atomic absorption system. The metal binding capability of PLHis-CPG was determined through the analysis of the generated breakthrough curves. The polymer likely coordinates cationic metals through the imidazole side chain (pK a ∼6) present on each histidine residue with both strong and weak binding sites for Cu 2+ , Cd 2+ , Co 2+ , and Ni 2+ . Weak to minimal binding was observed for Mn 2+ , Ca 2+ , Mg 2+ , Na + , and Cr 3+ . The bound metals are quantitatively released from the column with an acid strip. It has also been shown that the protonated imidazole side chain present in acidic solutions is capable of binding metal oxyanions such as chromates, arsenates, and selenites; although oxyanion binding currently exhibits interferences from competing anions in solution, such as sulfate and nitrate. The interference in oxyanion binding is less severe in the presence of chloride, phosphate, and acetate. PLHis-CPG exhibits a capacity of ∼30 μmol Cu 2+ /g CPG in neutral to basic conditions, and a capacity of ∼70 μmol Cr(VI)/g CPG, ∼4 μmol As(V)/g CPG, and ∼4 μmol Se(IV)/g CPG in acidic conditions

  6. Differences in EDTA-assisted metal phytoextraction between metallicolous and non-metallicolous accessions of Rumex acetosa L

    Energy Technology Data Exchange (ETDEWEB)

    Barrutia, Oihana, E-mail: oihana.barrutia@ehu.e [Department of Plant Biology and Ecology, University of the Basque Country/EHU, P. O. Box 644, E-48080 Bilbao (Spain); Garbisu, Carlos; Hernandez-Allica, Javier [NEIKER-Tecnalia, Basque Institute of Agricultural Research and Development, c/ Berreaga 1, E-48160 Derio (Spain); Garcia-Plazaola, Jose Ignacio; Becerril, Jose Maria [Department of Plant Biology and Ecology, University of the Basque Country/EHU, P. O. Box 644, E-48080 Bilbao (Spain)

    2010-05-15

    Two common sorrel (Rumex acetosa) accessions, one from a Zn-Pb contaminated site (CS accession) and the other from an uncontaminated site (UCS accession), were hydroponically exposed to a mixture of heavy metals (Pb{sup 2+} + Zn{sup 2+} + Cd{sup 2+}) with and without EDTA at an equimolar rate. The metallicolous CS accession showed a higher tolerance to metal treatment in the absence of the chelating agent, whereas the UCS accession was especially tolerant to EDTA treatment alone. Combination of metal and EDTA treatment resulted in a higher Pb accumulation in shoots of both accessions although plants hardly showed phytotoxic symptoms. Cd and Zn uptake was not augmented by EDTA addition to the polymetallic medium. Chelant-assisted Pb accumulation was 70% higher in the CS accession than in the UCS accession, despite the fact that the former accession evapotranspired less water than the UCS accession. These results support the existence of a non-selective apoplastic transport of metal chelates by R. acetosa roots, not related to transpiration stream. - A partial intolerance of plants to a certain chelating agent can contribute to the understanding of the mechanisms and pathways of metal chelates uptake.

  7. Differences in EDTA-assisted metal phytoextraction between metallicolous and non-metallicolous accessions of Rumex acetosa L

    International Nuclear Information System (INIS)

    Barrutia, Oihana; Garbisu, Carlos; Hernandez-Allica, Javier; Garcia-Plazaola, Jose Ignacio; Becerril, Jose Maria

    2010-01-01

    Two common sorrel (Rumex acetosa) accessions, one from a Zn-Pb contaminated site (CS accession) and the other from an uncontaminated site (UCS accession), were hydroponically exposed to a mixture of heavy metals (Pb 2+ + Zn 2+ + Cd 2+ ) with and without EDTA at an equimolar rate. The metallicolous CS accession showed a higher tolerance to metal treatment in the absence of the chelating agent, whereas the UCS accession was especially tolerant to EDTA treatment alone. Combination of metal and EDTA treatment resulted in a higher Pb accumulation in shoots of both accessions although plants hardly showed phytotoxic symptoms. Cd and Zn uptake was not augmented by EDTA addition to the polymetallic medium. Chelant-assisted Pb accumulation was 70% higher in the CS accession than in the UCS accession, despite the fact that the former accession evapotranspired less water than the UCS accession. These results support the existence of a non-selective apoplastic transport of metal chelates by R. acetosa roots, not related to transpiration stream. - A partial intolerance of plants to a certain chelating agent can contribute to the understanding of the mechanisms and pathways of metal chelates uptake.

  8. Separations chemistry of toxic metals

    International Nuclear Information System (INIS)

    Smith, P.; Barr, M.; Barrans, R.

    1996-01-01

    Sequestering and removing toxic metal ions from their surroundings is an increasingly active area of research and is gaining importance in light of current environmental contamination problems both within the DOE complex and externally. One method of separating metal ions is to complex them to a molecule (a ligand or chelator) which exhibits specific binding affinity for a toxic metal, even in the presence of other more benign metals. This approach makes use of the sometimes subtle differences between toxic and non-toxic metals resulting from variations in size, charge and shape. For example, toxic metals such as chromium, arsenic, and technetium exist in the environment as oxyanions, negatively charged species with a characteristic tetrahedral shape. Other toxic metals such as actinides and heavy metals are positively charged spheres with specific affinities for particular donor atoms such as oxygen (for actinides) and nitrogen (for heavy metals). In most cases the toxic metals are found in the presence of much larger quantities of less toxic metals such as sodium, calcium and iron. The selectivity of the chelators is critical to the goal of removing the toxic metals from their less toxic counterparts. The approach was to build a ligand framework that complements the unique characteristics of the toxic metal (size, charge and shape) while minimizing interactions with non-toxic metals. The authors have designed ligands exhibiting specificity for the target metals; they have synthesized, characterized and tested these ligands; and they have shown that they exhibit the proposed selectivity and cooperative binding effects

  9. Sequestration of chelated copper by structural Fe(II): Reductive decomplexation and transformation of Cu{sup II}-EDTA

    Energy Technology Data Exchange (ETDEWEB)

    He, Hongping [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China); Wu, Deli, E-mail: wudeli@tongji.edu.cn [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China); Zhao, Linghui [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China); Luo, Cong [School of Civil and Environmental Engineering, Georgia Institute of Technology, GA 30332 (United States); Dai, Chaomeng; Zhang, Yalei [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China)

    2016-05-15

    sequestration. Given the high feasibility and reactivity, =Fe(II) may provide a potential alternative in chelated metals pollution controlling.

  10. Role of chelates in magnetic resonance imaging studies

    Directory of Open Access Journals (Sweden)

    Tripathi Laxmi

    2009-01-01

    Full Text Available Imaging studies are tests performed with a variety of techniques that produce pictures of the inside of a patient′s body. Magnetic resonance imaging (MRI is an imaging technique based on the principles of nuclear magnetic resonance. MRI uses a powerful magnetic field, radio waves, and a computer to produce detailed pictures of organs, soft tissues, bone, and virtually all other internal body structures. Chelates have a wide application in such imaging techniques. Chelates in imaging studies are used alone as radioactive agents or conjugated to monoclonal antibodies or to DNA as radioactive agents. Technetium chelates and gadolinium chelates are being widely used as magnetic resonance contrast media.

  11. Photophysical investigation of energy transfer luminescence of lanthanide chelates with aromatic polyaminocarboxylate ligands in aqueous solutions

    International Nuclear Information System (INIS)

    Hoshino, Hitoshi; Saitoh, Takashi; Yotsuyanagi, Takao

    1995-01-01

    Some photophysical data including emission lifetimes (τ), total emission quantum yields (Φ), and ligand phosphorescence data are reported for the energy-transfer luminescence of the Eu(III) chelate of Quin 2 and the Tb(III) chelate of BAPTA: Quin 2 means 2-[(2-amino-5-methylphenoxy)methyl]-6-methoxy-8-aminoquinoline-N,N,N',N'-tetraacetic acid; BAPTA means 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. The energy diagrams for the ligand T 1 and the metal-center f-f levels are proposed. The τ values of Tb(III)-BAPTA chelates are 1.73 ms in H 2 O and 3.44 ms in D 2 O. The Eu(III)-Quin 2 chelate system shows a bi-exponential decay of emission; τ=0.048 and 0.20 ms in H 2 O and 0.066 and 1.44 ms in D 2 O. The Quin 2 chelate is kinetically inert, so that the interchange of these two conformer structures are very slow at room temperature. The number of water molecules in the primary coordination sphere is calculated from the lifetime data to be 1.9-2.4 for Eu-Quin 2 and 0.5 for Tb-BAPTA. The Φ values in aqueous solutions are rather small in these systems; 0.009 for Tb-BAPTA and 0.0023 for Eu-Quin 2, but these are enough counterbalanced by the large molar absorptivities giving the great sensitization factors for the ions; the sensitization factors against each aqua ion are 1380 for Eu-Quin 2 and 1600 for Tb-BAPTA. (author)

  12. Chelating agents to solubilize heavy metals from Oxisols contaminated by the addition of organic and inorganic residues Uso de quelantes na solubilização de metais pesados de Latossolos contaminados pela adição de resíduos orgânico e inorgânico

    Directory of Open Access Journals (Sweden)

    Aline Renée Coscione

    2009-02-01

    Full Text Available Phytoremediation is an attractive technique for soils contaminated with heavy metals, especially in conjunction with chelating agents to assist metal phytoextraction. Nevertheless, their studies in Brazil are rare. Thus, the objective of the present work was to evaluate the efficiency of the chelating agents EDDS and EDTA for the solubilization of heavy metals from two Oxisols contaminated by organic sources in Jaguariúna (LVJ and inorganic sources in Paulínia (LVP, São Paulo State, Southeastern Brazil. First, the soil samples were fractionated and the DTPA method was used to quantify heavy metals available forms. The results indicated that the metals were highly available in the soil fractions and could be solubilized by the chelating agents. The soil was suspended for 24 h in a chelating agent solution (EDTA or EDDS at rates of 0, 250, 500 and 750 mg kg-1 of soil. The concentration of solubilized heavy metals was determined in the resulting solution. The extent of metal solubilization varied according to soil type, the chelating agent added and the specific metal. The amount of iron solubilized, as compared to the total iron (LVJ was 11% (EDTA and 19% (EDDS. EDDS solubilized more Cu than EDTA in both soils but more Ni in LVJ, while EDTA solubilized more Zn in both soils but more Cd in LVP. Both EDTA and EDDS may be useful for phytoextraction from soils, although the iron content is an important factor regarding the phytoextraction of heavy metals with chelating agents in Oxisols.A fitoextração tem sido uma opção atrativa para remediar solos contaminados com metais pesados, principalmente quando associada à aplicação de quelantes ao solo, embora no Brasil seus estudos sejam muito incipientes. Portanto, o objetivo deste trabalho foi avaliar a eficiência dos quelantes EDTA e EDDS na solubilização de metais pesados em Latossolos contaminados por Cu, Zn, Cd e Ni, cujas fontes de contaminação foram: orgânica em Jaguariúna (LVJ e

  13. Obligatory reduction of ferric chelates in iron uptake by soybeans.

    Science.gov (United States)

    Chaney, R L; Brown, J C; Tiffin, L O

    1972-08-01

    The contrasting Fe(2+) and Fe(3+) chelating properties of the synthetic chelators ethylenediaminedi (o-hydroxyphenylacetate) (EDDHA) and 4,7-di(4-phenylsulfonate)-1, 10-phenanthroline (bathophenanthrolinedisulfonate) (BPDS) were used to determine the valence form of Fe absorbed by soybean roots supplied with Fe(3+)-chelates. EDDHA binds Fe(3+) strongly, but Fe(2+) weakly; BPDS binds Fe(2+) strongly but Fe(3+) weakly. Addition of an excess of BPDS to nutrient solutions containing Fe(3+)-chelates inhibited soybean Fe uptake-translocation by 99+%; [Fe(II) (BPDS)(3)](4-) accumulated in the nutrient solution. The addition of EDDHA caused little or no inhibition. These results were observed with topped and intact soybeans. Thus, separation and absorption of Fe from Fe(3+)-chelates appear to require reduction of Fe(3+)-chelate to Fe(2+)-chelate at the root, with Fe(2+) being the principal form of Fe absorbed by soybean.

  14. Impact of iron chelators on short-term dissolution of basaltic glass

    Science.gov (United States)

    Perez, Anne; Rossano, Stéphanie; Trcera, Nicolas; Verney-Carron, Aurélie; Huguenot, David; van Hullebusch, Eric D.; Catillon, Gilles; Razafitianamaharavo, Angelina; Guyot, François

    2015-08-01

    Although microorganisms seem to play an important role in the alteration processes of basaltic glasses in solution, the elementary mechanisms involved remain unclear in particular with regard to the role of organic ligands excreted by the cells. Two glasses, one with Fe and one without Fe were synthesized to model basaltic glass compositions. Fe in the glass was mostly Fe(III) for enhancing interaction with siderophores, yet with small but significant amounts of Fe(II) (between 10% and 30% of iron). The prepared samples were submitted to abiotic alteration experiments in buffered (pH 6.4) diluted solutions of metal-specific ligands, namely oxalic acid (OA, 10 mM), desferrioxamine (DFA, 1 mM) or 2,2‧-bipyridyl (BPI, 1 mM). Element release from the glass into the solution after short term alteration (maximum 1 week) was measured by ICP-OES, and normalized mass losses and relative release ratios (with respect to Si) were evaluated for each element in each experimental condition. The presence of organic ligands had a significant effect on the dissolution of both glasses. Trivalent metals chelators (OA, DFA) impacted on the release of Fe3+ and Al3+, and thus on the global dissolution of both glasses, enhancing all release rates and dissolution stoichiometry (release rates were increased up to 7 times for Al or Fe). As expected, the mostly divalent metal chelator BPI interacted preferentially with Ca2+, Mg2+ and Fe2+. This study thus allows to highlight the central roles of iron and aluminium in interaction with some organic ligands in the alteration processes of basaltic glasses. It thus provides a step toward understanding the biological contribution of this fundamental geological process.

  15. EDGA amendment of slightly heavy metal loaded soil affects heavy metal solubility, crop growth and microbivorous nematodes but not bacteria and herbivorous nematodes

    NARCIS (Netherlands)

    Bouwman, L.A.; Bloem, J.; Römkens, P.F.A.M.; Japenga, J.

    2005-01-01

    Phytoextraction of heavy metals is a promising technology to remediate slightly and moderately contaminated soils. To enhance crops' uptake of heavy metals, chelates such as EDGA are being tested as soil additives. Heavy metal loaded EDGA can affect soil organisms such as bacteria and nematodes in

  16. Antiparkinson drug--Mucuna pruriens shows antioxidant and metal chelating activity.

    Science.gov (United States)

    Dhanasekaran, Muralikrishnan; Tharakan, Binu; Manyam, Bala V

    2008-01-01

    Parkinson's disease is a neurodegenerative disorder for which no neurorestorative therapeutic treatment is currently available. Oxidative stress plays an important role in the pathophysiology of Parkinson's disease. The ancient Indian medical system, Ayurveda, traditionally uses Mucuna pruriens to treat Parkinson's disease. In our earlier studies, Mucuna pruriens has been shown to possess antiparkinson and neuroprotective effects in animal models of Parkinson's disease. The antioxidant activity of Mucuna pruriens was demonstrated by its ability to scavenge DPPH radicals, ABTS radicals and reactive oxygen species. Mucuna pruriens significantly inhibited the oxidation of lipids and deoxyribose sugar. Mucuna pruriens exhibited divalent iron chelating activity and did not show any genotoxic/mutagenic effect on the plasmid DNA. These results suggest that the neuroprotective and neurorestorative effect of Mucuna pruriens may be related to its antioxidant activity independent of the symptomatic effect. In addition, the drug appears to be therapeutically safe in the treatment of patients with Parkinson's disease. Copyright (c) 2007 John Wiley & Sons, Ltd.

  17. Fabrication of Surface Protein-Imprinted Nanoparticles Using a Metal Chelating Monomer via Aqueous Precipitation Polymerization.

    Science.gov (United States)

    Li, Wei; Sun, Yan; Yang, Chongchong; Yan, Xianming; Guo, Hao; Fu, Guoqi

    2015-12-16

    Molecular imprinting is a promising way for constructing artificial protein recognition materials, but it has been challenged by difficulties such as restricted biomacromolecule transfer in the cross-linked polymer networks, and reduced template-monomer interactions that are due to the required aqueous media. Herein, we propose a strategy for imprinting of histidine (His)-exposed proteins by combining previous approaches such as surface imprinting over nanostructures, utilization of metal coordination interactions, and adoption of aqueous precipitation polymerization capable of forming reversible physical crosslinks. With lysozyme as a model template bearing His residues, imprinted polymer nanoshells were grafted over vinyl-modified nanoparticles by aqueous precipitation copolymerization of a Cu(2+) chelating monomer with a temperature-responsive monomer carried out at 37 °C, above the volume phase-transition temperature (VPTT) of the final copolymer. The imprinted nanoshells showed significant temperature sensitivity and the template removal could be facilitated by swelling of the imprinted layers at 4 °C, below the VPTT. The resultant core-shell imprinted nanoparticles exhibited strikingly high rebinding selectivity against a variety of nontemplate proteins. An imprinting factor up to 22.7 was achieved, which is among the best values reported for protein imprinting, and a rather high specific binding capacity of 67.3 mg/g was obtained. Moreover, this approach was successfully extended to preliminary imprinting of hemoglobin, another protein with accessible His. Therefore, it may be a versatile method for fabrication of high-performance surface-imprinted nanoparticles toward His-exposed proteins.

  18. by Phanerochaete chrysosporium from a binary metal system

    African Journals Online (AJOL)

    drinie

    2001-01-01

    Jan 1, 2001 ... metal concentrations (Ci) increased, independent of initial pH (pHi) and generally the metal with ... The results also show that some portion of the metal ions sorbed by P. ... mechanisms, mainly ion exchange, chelation, adsorption, and ..... YU Q and KAEWSARN P (1999) Binary adsorption of copper(II) and.

  19. Development of iron chelators for Cooley's anemia. Final report

    International Nuclear Information System (INIS)

    Crosby, W.H.; Green, R.

    1982-01-01

    Iron chelators were screened in an iron-loaded rat model using selective radioiron probes. In all experiments, chelators D and F, in that order, induced significant loss of radioiron compared with controls. However, use of chelator D was associated with side effects, and resulted in the death of some animals. There was some evidence that chelator A also caused iron loss significantly greater than controls. Chelators B, C and E were without apparent enhancing effect on radioiron excretion. This was a blind study and the compounds used were A - 2,3-Dihydroxybenzoic acid; B - N,N1-Dimethyladipohydroxamic acid; C - DL-Phenylalanine hydroxamic acid; D - Ethylenediamine-N,N1-bis(2-hydroxphenylacetic acid); E - Propionohydroxamic acid; and F - Deferrioxamine B

  20. Metal Pollutants and Cardiovascular Disease: Mechanisms and Consequences of Exposure

    Science.gov (United States)

    Solenkova, Natalia V.; Newman, Jonathan D.; Berger, Jeffrey S.; Thurston, George; Hochman, Judith S.; Lamas, Gervasio A.

    2014-01-01

    Introduction There is epidemiological evidence that metal contaminants may play a role in the development of atherosclerosis and its complications. Moreover, a recent clinical trial of a metal chelator had a surprisingly positive result in reducing cardiovascular events in a secondary prevention population, strengthening the link between metal exposure and cardiovascular disease (CVD). This is, therefore, an opportune moment to review evidence that exposure to metal pollutants, such as arsenic, lead, cadmium, and mercury, are significant risk factors for CVD. Methods We reviewed the English-speaking medical literature to assess and present the epidemiological evidence that 4 metals having no role in the human body (xenobiotic), mercury, lead, cadmium, and arsenic, have epidemiologic and mechanistic links to atherosclerosis and CVD. Moreover, we briefly review how the results of the Trial to Assess Chelation Therapy strengthen the link between atherosclerosis and xenobiotic metal contamination in humans. Conclusions There is strong evidence that xenobiotic metal contamination is linked to atherosclerotic disease and is a modifiable risk factor. PMID:25458643

  1. On the methodology of radiochemical neutron activation analysis of noble metals

    International Nuclear Information System (INIS)

    Chai, C.F.; Ma, S.L.; Mao, X.Y.; Liao, K.N.; Liu, W.C.

    1986-01-01

    Two different radiochemical procedures were developed: chelate ion resin exchange and amine solvent extraction. Two kinds of new Chinese chelate resins (NANKAI-3926 and BEI-5) and a new long-chain primary amine N 1923 were compared with Srafion NMRR and the tertiary amine N 235 in absorption performance of noble metals, respectively. Influences of various experimental conditions, e.g. sample digestion, acidity, equilibrium time, as well as elution of noble metals, on analytical sensitivity and chemical yield were discussed. Combining with neutron activation, the radiochemical separation procedures developed were used to determine the noble metal contents in the geological samples from Permina/Triassic boundary in South China. (author)

  2. Structural, Chemical and Biological Aspects of Antioxidants for Strategies Against Metal and Metalloid Exposure

    Directory of Open Access Journals (Sweden)

    Swaran J. S. Flora

    2009-01-01

    Full Text Available Oxidative stress contributes to the pathophysiology of exposure to heavy metals/metalloid. Beneficial renal effects of some medications, such as chelation therapy depend at least partially on the ability to alleviate oxidative stress. The administration of various natural or synthetic antioxidants has been shown to be of benefit in the prevention and attenuation of metal induced biochemical alterations. These include vitamins, N-acetylcysteine, α-lipoic acid, melatonin, dietary flavonoids and many others. Human studies are limited in this regard. Under certain conditions, surprisingly, the antioxidant supplements may exhibit pro-oxidant properties and even worsen metal induced toxic damage. To date, the evidence is insufficient to recommend antioxidant supplements in subject with exposure to metals. Prospective, controlled clinical trials on safety and effectiveness of different therapeutic antioxidant strategies either individually or in combination with chelating agent are indispensable. The present review focuses on structural, chemical and biological aspects of antioxidants particularly related to their chelating properties.

  3. Design, synthesis and biological evaluation of multifunctional tacrine-curcumin hybrids as new cholinesterase inhibitors with metal ions-chelating and neuroprotective property.

    Science.gov (United States)

    Liu, Zhikun; Fang, Lei; Zhang, Huan; Gou, Shaohua; Chen, Li

    2017-04-15

    Total sixteen tacrine-curcumin hybrid compounds were designed and synthesized for the purpose of searching for multifunctional anti-Alzheimer agents. In vitro studies showed that these hybrid compounds showed good cholinesterase inhibitory activity. Particularly, the potency of K 3-2 is even beyond tacrine. Some of the compounds exhibited different selectivity on acetylcholinesterase or butyrylcholinesterase due to the structural difference. Thus, the structure and activity relationship is summarized and further discussed based on molecular modeling studies. The ORAC and MTT assays indicated that the hybrid compounds possessed pronounced antioxidant activity and could effectively protect PC12 cells from the H 2 O 2 /Aβ42-induced toxicity. Moreover, the hybrid compounds also showed positive metal ions-chelating ability in vitro, suggesting a potential to halt ion-induced Aβ aggregation. All the obtained results demonstrated that the tacrine-curcumin hybrid compounds, in particular compound K 3-2 , can be considered as potential therapeutic agents for Alzheimer's disease. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Mechanisms of oxide dissolution by acid chelating agents

    International Nuclear Information System (INIS)

    Blesa, M.A.; Maroto, A.J.G.

    1982-01-01

    In this paper, the different possible rate controlling processes in the dissolution of metallic oxides are examined. In particular, the following situations are assessed: mass-transfer control; coupling of mass-transfer and reactions at the interface; interface equilibration with the solution; various interface disruption and reconstruction phenomena. For each of the above mentioned cases, the influence of variables such as reagent concentration, temperature, pH, fluid hydrodynamics and general and specific catalysts is discussed. Depending upon the particular situation it is found that a more rational basis for the development of reagent is given by these considerations. The influence of chelating agents on both the thermodynamics and kinetics of the process is discussed, and the results of experimental studies in batch on magnetite and various ferrites are presented and discussed. For this purpose, several reagents were studied, including some very effective ones like thioglycolic acid, and others commonly used in actual decontamination, like ethylenediaminetetraacetic acid and oxalic acid. The relation to other (reductive) chemical decontamination procedures is discussed. The relevance of these studies to decontamination of metallic surfaces is discussed

  5. Solvent extraction of noble metals by formazans

    International Nuclear Information System (INIS)

    Grote, M.; Hueppe, U.; Kettrup, A.

    1984-01-01

    The extraction properties of ion-pairs composed of quaternary ammonium cations and a sulphonated formazan were compared with those of an unsulphonated formazan, for various solvent media. In dichloromethane the combined system behaves as a 'coloured anion-exchanger', with displacement of the sulphonated formazan, whereas in toluene Pd(II) and Ag(I) are extracted as the metal formazan chelates from aqueous medium. The rates of extraction are remarkably higher than with the simple extractants. Because of the higher stability only the simple chelating extraction systems afford satisfactory separation of Pd(II) from excess of Pt(IV) and of Ag(I) from Cu(II). The extracted metals can be stripped and the extractant regenerated. (author)

  6. Phosphinic acid functionalized polyazacycloalkane chelators for radiodiagnostics and radiotherapeutics: unique characteristics and applications.

    Science.gov (United States)

    Notni, Johannes; Šimeček, Jakub; Wester, Hans-Jürgen

    2014-06-01

    Given the wide application of positron emission tomography (PET), positron-emitting metal radionuclides have received much attention recently. Of these, gallium-68 has become particularly popular, as it is the only PET nuclide commercially available from radionuclide generators, therefore allowing local production of PET radiotracers independent of an on-site cyclotron. Hence, interest in optimized bifunctional chelators for the elaboration of (68) Ga-labeled bioconjugates has been rekindled as well, resulting in the development of improved triazacyclononane-triphosphinate (TRAP) ligand structures. The most remarkable features of these ligands are unparalleled selectivity for Ga(III) , rapid Ga(III) complexation kinetics, extraordinarily high thermodynamic stability, and kinetic inertness of the respective Ga(III) chelates. As a result, TRAP chelators exhibit very favorable (68) Ga-labeling properties. Based on the scaffolds NOPO (1,4,7-triazacyclononane-1,4-bis[methylene(hydroxymethyl)phosphinic acid]-7-[methylene(2-carboxyethyl)phosphinic acid]) and TRAP-Pr, tailored for convenient preparation of (68) Ga-labeled monomeric and multimeric bioconjugates, a variety of novel (68) Ga radiopharmaceuticals have been synthesized. These include bisphosphonates, somatostatin receptor ligands, prostate-specific membrane antigen (PSMA)-targeting peptides, and cyclic RGD pentapeptides, for in vivo PET imaging of bone, neuroendocrine tumors, prostate cancer, and integrin expression, respectively. Furthermore, TRAP-based (68) Ga-labeled gadolinium(III) complexes have been proposed as bimodal probes for PET/MRI, and a cyclen-based analogue of TRAP-Pr has been suggested for the elaboration of targeted radiotherapeutics comprising radiolanthanide ions. Thus, polyazacycloalkane-based polyphosphinic acid chelators are a powerful toolbox for pharmaceutical research, particularly for the development of (68) Ga radiopharmaceuticals. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. 3,4,5-trihydroxybenzoic acid as chelating agent

    International Nuclear Information System (INIS)

    Agrawal, M.D.; Bhandari, C.S.; Dixit, M.K.; Sogani, N.C.

    1976-01-01

    Stability constants of praseodymium chelates of 3,4,5-trihydroxy sodium benzoate are determined by using Bjerrum-Calvin pH titration techniques at constant ionic strength 0.1M-sodium perchlorate and at 28+-0.1 0 C. Values calculated by different methods are in good agreement. The study reveals that during complexation only one proton of the ligand molecule is replaced by the metal and oxygen of adjacent phenolic group acts as a coordinating atom. IR and NMR spectral studies of the ligand reveal that one of the OH groups (in meta position to carboxylic group) remains free while two other phenolic groups are involved in intramolecular hydrogen bonding. One water molecule is found attached in crystalline gallic acid. (author)

  8. Mixed Metal Complexes of Isoniazid and Ascorbic Acid: Chelation ...

    African Journals Online (AJOL)

    HP

    these ligands and their metal complexes have revealed the bi-dentate coordination of isoniazid ligand to ... of the drugs on coordination with a metal is enhanced ..... James, O.O., Nwinyi, C.O. and. Allensela, M.A. (2008). Cobalt(II) complexes of mixed antibiotics: Synthesis,. Characterization, antimicrobial potential and their.

  9. A simplified suite of methods to evaluate chelator conjugation of antibodies: effects on hydrodynamic radius and biodistribution

    International Nuclear Information System (INIS)

    Al-Ejeh, Fares; Darby, Jocelyn M.; Thierry, Benjamin; Brown, Michael P.

    2009-01-01

    Introduction: Antibodies covalently conjugated with chelators such as 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) are required for radioimmunoscintigraphy and radioimmunotherapy, which are of growing importance in cancer medicine. Method: Here, we report a suite of simple methods that provide a preclinical assessment package for evaluating the effects of DOTA conjugation on the in vitro and in vivo performance of monoclonal antibodies. We exemplify the use of these methods by investigating the effects of DOTA conjugation on the biochemical properties of the DAB4 clone of the La/SSB-specific murine monoclonal autoantibody, APOMAB (registered) , which is a novel malignant cell death ligand. Results: We have developed a 96-well microtiter-plate assay to measure directly the concentration of DOTA and other chelators in antibody-chelator conjugate solutions. Coupled with a commercial assay for measuring protein concentration, the dual microtiter-plate method can rapidly determine chelator/antibody ratios in the same plate. The biochemical properties of DAB4 immunoconjugates were altered as the DOTA/Ab ratio increased so that: (i) mass/charge ratio decreased; (ii) hydrodynamic radius increased; (iii) antibody immunoactivity decreased; (iv) rate of chelation of metal ions and specific radioactivity both increased and in vivo, (v) tumor uptake decreased as nonspecific uptake by liver and spleen increased. Conclusion: This simplified suite of methods readily identifies biochemical characteristics of the DOTA-immunoconjugates such as hydrodynamic diameter and decreased mass/charge ratio associated with compromised immunotargeting efficiency and, thus, may prove useful for optimizing conjugation procedures in order to maximize immunoconjugate-mediated radioimmunoscintigraphy and radioimmunotherapy.

  10. Animal experimental investigations of the problem of the decorporation of radioactive metal ions

    International Nuclear Information System (INIS)

    Berner, W.

    1973-01-01

    Basically, it is possible to reduce the radiation exposure by excretion intensification of incorporated radioactive materials. Chelate agents have proved to be particularly effective for the accelerated elimination of radioactive metal ions. The kinetics of the distribution and excretion of 57 CoCl 2 , 65 ZnCl 2 and 203 HgCl 2 on the rat under the influence of the chelating agent penicillamin (D-ββ-dimethylcystein) was investigated and the reduction of the radiation exposure in man was calculated from the animal-experimentally gained data. At various times after the incorporation of metal ions, the whole body radioactivity and, after killing the animals, the radioactivity of the organs liver, kidney, spleen, skeleton, muscles and blood, were measured. From the course of the measured radioactivities with time, the biokinetic data of the radioactive metal ions (effective half-lives, selection factors and their components) were determined by means of regression analyses. The chelating agent was applied at different times before or after incorporation of the radioactive metal ions. (EK/LH) [de

  11. Influence of non-migratory metal-chelating active packaging film on food quality: impact on physical and chemical stability of emulsions.

    Science.gov (United States)

    Tian, Fang; Decker, Eric A; McClements, D Julian; Goddard, Julie M

    2014-05-15

    Previously, we developed a novel metal-chelating packaging film (PP-g-PAA) by grafting acrylic acid (AA) monomer from polypropylene (PP) film surface, and demonstrated its potential in controlling iron-promoted lipid oxidation. Herein, we further established the industrial practicality of this active film. Specifically, the influence of film surface area-to-product volume ratio (SA/V) and product pH on the application of the film was investigated using an oil-in-water emulsion system. The films equally inhibited lipid oxidation throughout the range of SA/V ratios tested (2-8 cm(2)/ml). PP-g-PAA films were most effective at pH 7.0, and the activity decreased with decreasing pH. The particle size examination of emulsions indicated no adverse influence from the active film on the stability of this emulsion system. FTIR analysis suggested a non-migratory nature of PP-g-PAA films. These results provide fundamental knowledge that will facilitate the application of this effective and economical active packaging film in the food industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. The Extracellular Domain of Human High Affinity Copper Transporter (hNdCTR1), Synthesized by E. coli Cells, Chelates Silver and Copper Ions In Vivo.

    Science.gov (United States)

    Sankova, Tatiana P; Orlov, Iurii A; Saveliev, Andrey N; Kirilenko, Demid A; Babich, Polina S; Brunkov, Pavel N; Puchkova, Ludmila V

    2017-11-03

    There is much interest in effective copper chelators to correct copper dyshomeostasis in neurodegenerative and oncological diseases. In this study, a recombinant fusion protein for expression in Escherichia coli cells was constructed from glutathione-S-transferase (GST) and the N-terminal domain (ectodomain) of human high affinity copper transporter CTR1 (hNdCTR1), which has three metal-bound motifs. Several biological properties of the GST-hNdCTR1 fusion protein were assessed. It was demonstrated that in cells, the protein was prone to oligomerization, formed inclusion bodies and displayed no toxicity. Treatment of E. coli cells with copper and silver ions reduced cell viability in a dose- and time-dependent manner. Cells expressing GST-hNdCTR1 protein demonstrated resistance to the metal treatments. These cells accumulated silver ions and formed nanoparticles that contained AgCl and metallic silver. In this bacterial population, filamentous bacteria with a length of about 10 µm were often observed. The possibility for the fusion protein carrying extracellular metal binding motifs to integrate into the cell's copper metabolism and its chelating properties are discussed.

  13. Bis-ligated Ti and Zr complexes of chelating N-heterocyclic carbenes

    KAUST Repository

    El-Batta, Amer

    2011-07-01

    In this communication we report the synthesis of novel titanium and zirconium complexes ligated by bidentate "salicylaldimine-like" N-heterocyclic carbenes (NHC). Double addition of the NHC chelate to either TiCl4(thf)2 or ZrCl4 forms bis-ligated organometallic fragments with a distorted octahedral geometry. These complexes are rare examples of group IV transition-metal NHC adducts. Preliminary catalytic tests demonstrate that in the presence of methylaluminoxane (MAO) these complexes are useful initiators for the polymerization of ethylene and the copolymerization of ethylene with norbornene and 1-octene. © 2011 Elsevier B.V. All rights reserved.

  14. Use of chelating agents as immovable phase in extraction chromatography

    International Nuclear Information System (INIS)

    Sebesta, F.

    1978-01-01

    Extraction chromatography using chelating agents is reviewed. The theory of element extraction by chelating agents and factors influencing this process (pH, extracting agent concentration in organic phase, masking agent concentration in aqueous phase) are briefly considered. The effect of kinetic factors on the extraction chromatography process is discussed. Ways of preparing columns are emphasized. Examples of using chelating reagents in various extraction chromatography systems are given. β-Diketones, oximes, hydroxamic acids, dithizon, diethyl dithiocarbamic acid are chosen as chelating agents

  15. Enhanced NO{sub x} removal in wet scrubbers using metal chelates. Final report, Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-12-01

    Successful pilot plant tests of simultaneous removal of SO{sub 2} and NO{sub x} in a wet lime flue gas desulfurization system were concluded in December. The test, at up to 1.5 MW(e) capacity, were conducted by the Cincinnati Gas and Electric Company and Dravo Lime Company for the US Department of Energy at a pilot plant facility at the Miami Fort station of CG&E near Cincinnati, Ohio. The pilot plant scrubbed a slipstream of flue gas from Unit 7 a 530 MW coal-fired electric generating unit. Tests were conducted in three phases between April and December. The technology tested was wet scrubbing with Thiosorbic{reg_sign} magnesium-enhanced lime for SO{sub 2} removal and simultaneous NO scrubbing with ferrous EDTA, a metal chelate. Magnesium-enhanced lime-based wet scrubbing is used at 20 full-scale high-sulfur coal-fired electric generating units with a combined capacity of 8500 MW. Ferrous EDTA reacts with nitric oxide, NO, which comprises about 96% of NO{sub x} from coal-fired boilers. In this report, although not precise, NO and NO{sub x} are used interchangeably. A major objective of the tests was to combine NO{sub x} removal using ferrous EDTA, a developing technology, with SO{sub 2} removal using wet lime FGD, already in wide commercial use. If successful, this could allow wide application of this NO{sub x} removal technology. Volume 2 covers: description and results of NO{sub x} removal tests; and description and results of waste characterization studies.

  16. Theoretical study of the process of chelate ring scission in β-diketonates of metals. Basic state of lithium β-diketonates

    International Nuclear Information System (INIS)

    Sirenko, N.S.; L'vov, I.B.; Vovna, V.I.

    2000-01-01

    By the methods of Mndo and ab initio with configuration interaction (CI) accounting among them two variants of torsion scission of chelate ring in lithium malonodialdeginate and acetylacetonate are investigated. Effect of used approximation and optimization on calculated barriers of rotation and scission energies of metallocycle is estimated. It is shown that value of rotation barrier in ab initio approximation (2.0-2.5 eV) is for 30-100 % more then in MNDO approximation. Accounting of CI leads to insignificant changes of chelate ring scission energies and energy barriers as in direction of increase so in decrease one [ru

  17. Labeling of monoclonal antibodies with a 67Ga-phenolic aminocarboxylic acid chelate. Part I. Chemistry and labeling technique.

    Science.gov (United States)

    Schuhmacher, J; Matys, R; Hauser, H; Maier-Borst, W; Matzku, S

    1986-01-01

    As a chelating agent for labeling antibodies (Abs) with metallic radionuclides, a propionic acid substituted ethylenediamine N,N'-di-[(o-hydroxyphenyl) acetic acid] (P-EDDHA), which tightly complexes 67Ga, was synthesized. The 67Ga-P-EDDHA chelate was coupled in aqueous solution to IgG at a molar ratio of 1:1 via carbodiimide. The average coupling yield was 15%. A specific activity of 4 mCi/mg IgG could be obtained with commercially supplied 67Ga. In vitro stability was evaluated in human serum at 37 degrees C and showed a half-life of about 120 h for the release of 67Ga from the labeled Ab during the initial phase of incubation. This in vitro halflife is similar to that measured for 111In-DTPA labeled Abs. Because of the high stability of the 67Ga-P-EDDHA chelate, the in vivo formation of radioactive labeled transferrin by transchelation, as described for 111In-DTPA labeled Abs, should, however, be reduced by this labeling technique.

  18. Labeling of antibodies with a /sup 67/Ga-phenolic aminocarboxylic acid chelate. Pt. 1. Chemistry and labeling technique

    Energy Technology Data Exchange (ETDEWEB)

    Schuhmacher, J.; Matys, R.; Hauser, H.; Maier-Borst, W.; Matzku, S.

    1986-11-01

    As a chelating agent for labeling antibodies (Abs) with metallic radionuclides, a propionic acid substituted ethylenediamine N, N'-di-((o-hydroxyphenyl) acetic acid) (P-EDDHA), which tighly complexes /sup 67/Ga, was synthetized. The /sup 67/Ga-P-EDDHA chelate was coupled in aqueous solution to IgG at a molar ratio of 1:1 via carbodiimide. The average coupling yield was 15%. A specific activity of 4 mCi/mg IgG could be obtained with commercially supplied /sup 67/Ga. In vitro stability was evaluated in human serum at 37/sup 0/C and showed a half-life of about 120 h for the release of /sup 67/Ga from the labeled Ab during the initial phase of incubation. This in vitro halflife is similar to that measured for /sup 111/In-DTPA labeled Abs. Because of the high stability of the /sup 67/Ga-P-EDDHA chelate, the in vivo formation of radioactive lebeled transferrin by transchelation, as described for /sup 111/In-DTPA labeled Abs, should, however, be reduced by this labeling technique.

  19. Study of cyclization of chelating compounds using electrospray ionization mass spectrometry

    International Nuclear Information System (INIS)

    Shi Ying; Campbell, J.A.

    2000-01-01

    Electrospray ionization mass spectrometry (ESI-MS) was used for the study of cyclization of organic chelating compounds (chelators). Four chelating compounds were studied: Symmetrical ethylenediaminediacetic acid (s-EDDA), Unsymmetrical ethylenediaminediacetic acid (u-EDDA), N-(2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA), and N-(2-hydroxyethyl)iminodiacetic acid (HEIDA). The chelators were cyclized with treatments of acids and heating. The open and cyclized form of the chelators were semi-quantified by both positive and negative ion modes ESI-MS. The kinetics of chelator cyclization was studied as a function of reaction temperature and the pH of the matrix. The cyclization of s-EDDA was found to be a pseudo-first order reaction in s-EDDA and overall second order. The cyclizations of HEIDA and HEDTA are reversible reactions. Higher temperature and lower pH favors cyclization. (author)

  20. Macrocyclic chelator-coupled gastrin-based radiopharmaceuticals for targeting of gastrin receptor-expressing tumours

    Energy Technology Data Exchange (ETDEWEB)

    Good, Stephan; Wang, Xuejuan; Maecke, Helmut R. [University Hospital Basel, Division of Radiological Chemistry, Basel (Switzerland); Walter, Martin A.; Mueller-Brand, Jan [University Hospital, Institute of Nuclear Medicine, Basel (Switzerland); Waser, Beatrice; Reubi, Jean-Claude [University of Berne, Department of Pathology, Bern (Switzerland); Behe, Martin P. [Philipps-University of Marburg, Department of Nuclear Medicine, Marburg (Germany)

    2008-10-15

    Diethylenetriamine-pentaacetic acid (DTPA)-coupled minigastrins are unsuitable for therapeutic application with the available {beta}-emitting radiometals due to low complex stability. Low tumour-to-kidney ratio of the known radiopharmaceuticals is further limiting their potency. We used macrocyclic chelators for coupling to increase complex stability, modified the peptide sequence to enhance radiolytic stability and studied tumour-to-kidney ratio and metabolic stability using {sup 111}In-labelled derivatives. Gastrin derivatives with decreasing numbers of glutamic acids were synthesised using {sup 111}In as surrogate for therapeutic radiometals for in vitro and in vivo studies. Gastrin receptor affinities of the {sup nat}In-metallated compounds were determined by receptor autoradiography using {sup 125}I-CCK as radioligand. Internalisation was evaluated in AR4-2J cells. Enzymatic stability was determined by incubating the {sup 111}In-labelled peptides in human serum. Biodistribution was performed in AR4-2J-bearing Lewis rats. IC{sub 50} values of the {sup nat}In-metallated gastrin derivatives vary between 1.2 and 4.8 nmol/L for all methionine-containing derivatives. Replacement of methionine by norleucine, isoleucine, methionine-sulfoxide and methionine-sulfone resulted in significant decrease of receptor affinity (IC{sub 50} between 9.9 and 1,195 nmol/L). All cholecystokinin receptor affinities were >100 nmol/L. All {sup 111}In-labelled radiopeptides showed receptor-specific internalisation. Serum mean-life times varied between 2.0 and 72.6 h, positively correlating with the number of Glu residues. All {sup 111}In-labelled macrocyclic chelator conjugates showed higher tumour-to-kidney ratios after 24 h (0.37-0.99) compared to {sup 111}In-DTPA-minigastrin 0(0.05). Tumour wash out between 4 and 24 h was low. Imaging studies confirmed receptor-specific blocking of the tumour uptake. Reducing the number of glutamates increased tumour-to-kidney ratio but resulted in

  1. Macrocyclic chelator-coupled gastrin-based radiopharmaceuticals for targeting of gastrin receptor-expressing tumours

    International Nuclear Information System (INIS)

    Good, Stephan; Wang, Xuejuan; Maecke, Helmut R.; Walter, Martin A.; Mueller-Brand, Jan; Waser, Beatrice; Reubi, Jean-Claude; Behe, Martin P.

    2008-01-01

    Diethylenetriamine-pentaacetic acid (DTPA)-coupled minigastrins are unsuitable for therapeutic application with the available β-emitting radiometals due to low complex stability. Low tumour-to-kidney ratio of the known radiopharmaceuticals is further limiting their potency. We used macrocyclic chelators for coupling to increase complex stability, modified the peptide sequence to enhance radiolytic stability and studied tumour-to-kidney ratio and metabolic stability using 111 In-labelled derivatives. Gastrin derivatives with decreasing numbers of glutamic acids were synthesised using 111 In as surrogate for therapeutic radiometals for in vitro and in vivo studies. Gastrin receptor affinities of the nat In-metallated compounds were determined by receptor autoradiography using 125 I-CCK as radioligand. Internalisation was evaluated in AR4-2J cells. Enzymatic stability was determined by incubating the 111 In-labelled peptides in human serum. Biodistribution was performed in AR4-2J-bearing Lewis rats. IC 50 values of the nat In-metallated gastrin derivatives vary between 1.2 and 4.8 nmol/L for all methionine-containing derivatives. Replacement of methionine by norleucine, isoleucine, methionine-sulfoxide and methionine-sulfone resulted in significant decrease of receptor affinity (IC 50 between 9.9 and 1,195 nmol/L). All cholecystokinin receptor affinities were >100 nmol/L. All 111 In-labelled radiopeptides showed receptor-specific internalisation. Serum mean-life times varied between 2.0 and 72.6 h, positively correlating with the number of Glu residues. All 111 In-labelled macrocyclic chelator conjugates showed higher tumour-to-kidney ratios after 24 h (0.37-0.99) compared to 111 In-DTPA-minigastrin 0(0.05). Tumour wash out between 4 and 24 h was low. Imaging studies confirmed receptor-specific blocking of the tumour uptake. Reducing the number of glutamates increased tumour-to-kidney ratio but resulted in lower metabolic stability. The properties of the macrocyclic

  2. Chelation in metal intoxication. VIII. Removal of chromium from organs of potassium chromate administered rats.

    Science.gov (United States)

    Behari, J R; Tandon, S K

    1980-03-01

    Some polyaminocarboxylic acids were examined for their ability to mobilize chromium from certain vital organs, their subcellular fractions, and blood cells of potassium chromate administered rats. Hexamethylene 1,6-diamino tetraacetic acid (TDTA), triethylene tetramine hexaacetic acid (TTHA), and ethylene diamine di (O-hydroxylphenyl acetic acid) (EDDHA) may be useful in preventing or reducing chromate toxicity. No definite relationship could be observed between the structure of the chelating agents and their chromium-removing capacity.

  3. Direct current-induced electrogenerated chemiluminescence of hydrated and chelated Tb(III) at aluminum cathodes

    International Nuclear Information System (INIS)

    Hakansson, M.; Jiang, Q.; Spehar, A.-M.; Suomi, J.; Kotiranta, M.; Kulmala, S.

    2005-01-01

    Cathodic DC polarization of oxide-covered aluminum produces electrogenerated chemiluminescence from hydrated and chelated Tb(III) ions in aqueous electrolyte solutions. At the moment of cathodic voltage onset, a strong cathodic flash is observed, which is attributed to a tunnel emission of hot electrons into the aqueous electrolyte solution and the successive chemical reactions with the luminophores. However, within a few milliseconds the insulating oxide film is damaged and finally dissolved due to (i) indiffusion of protons or alkali metal ions into the thin oxide film, (ii) subsequent hydrogen evolution at the aluminum/oxide interface and (iii) alkalization of the electrode surface induced by hydrogen evolution reaction. When the alkalization of the electrode surface has proceeded sufficiently, chemiluminescence is generated with increasing intensity. Aluminum metal, short-lived Al(II), Al(I) or atomic hydrogen and its conjugated base form, hydrated electron, can act as highly reducing species in addition to the less energetic heterogeneously transferred electrons from the aluminum electrode. Tb(III) added as a hydrated ion in the solution probably luminesces in the form of Tb(OH) 3 or Tb(OH) 4 - by direct redox reactions of the central ion whereas multidentate aromatic ligand chelated Tb(III) probably luminesces by ligand sensitized chemiluminescence mechanism in which ligand is first excited by one-electron redox reactions, which is followed by intramolecular energy transfer to the central ion which finally emits light

  4. Metallomics for Alzheimer's disease treatment: Use of new generation of chelators combining metal-cation binding and transport properties.

    Science.gov (United States)

    D'Acunto, Cosimo Walter; Kaplánek, Robert; Gbelcová, Helena; Kejík, Zdeněk; Bříza, Tomáš; Vasina, Liudmila; Havlík, Martin; Ruml, Tomáš; Král, Vladimír

    2018-04-25

    Alzheimer's disease (AD) is a progressive neurodegenerative disorder affecting tens of million people. Currently marketed drugs have limited therapeutic efficacy and only slowing down the neurodegenerative process. Interestingly, it has been suggested that biometal cations in the amyloid beta (Aβ) aggregate deposits contribute to neurotoxicity and degenerative changes in AD. Thus, chelation therapy could represent novel mode of therapeutic intervention. Here we describe the features of chelators with therapeutically relevant mechanism of action. We have found that the tested compounds effectively reduce the toxicity of exogenous Aβ and suppress its endogenous production as well as decrease oxidative stress. Cholyl hydrazones were found to be the most active compounds. In summary, our data show that cation complexation, together with improving transport efficacy may represent basis for eventual treatment strategy in AD. Copyright © 2018. Published by Elsevier Masson SAS.

  5. Integrated Microanalytical System for Simultaneous Voltammetric Measurements of Free Metal Ion Concentrations in Natural Waters

    OpenAIRE

    Noël, Stéphane; Tercier-Waeber, Mary-Lou; Lin, Lin; Buffle, Jacques; Guenat, Olivier; Koudelka-Hep, Milena

    2007-01-01

    A complexing gel integrated microelectrode (CGIME) for direct measurements of free metal ion concentrations in natural waters has been developed. It is prepared by the successive deposition of microlayers of a chelating resin, an antifouling agarose gel and Hg on a 100-interconnected Ir-based microelectrode array. The trace metals of interest are in a first step accumulated on the chelating resin in proportion to their free ion concentration in solution, then released in acidic solution and d...

  6. Bifunctional chelates of Rh-105 and Au-199 as potential radiotherapeutic agents

    International Nuclear Information System (INIS)

    Troutner, D.E.; Schlemper, E.O.

    1990-01-01

    Since last year we have: continued the synthesis of pentadentate bifunctional chelating agents based on diethylene triamine; studied the chelation Rh-105, Au-198 (as model for Au-199) and Tc-99m with these agents as well as chelation of Pd-109, Cu-67, In-111, and Co-57 with some of them; synthesized a new class of potential bifunctional chelating agents based on phenylene diamine; investigated the behavior of Au-198 as a model for Au-199; begun synthesis of bifunctional chelating agents based on terpyridly and similar ligands; and continued attempts to produce tetradentate bifunctional chelates based on diaminopropane. Each of these will be addressed in this report

  7. Transport of significant metals recovered in real sea experiment of adsorbents

    International Nuclear Information System (INIS)

    Takeda, Hayato; Tamada, Masao; Kasai, Noboru; Katakai, Akio; Hasegawa, Shin; Seko, Noriaki; Sugo, Takanobu; Kawabata, Yukiya

    2001-10-01

    Real sea experiment for the recovery of significant metals such as uranium and vanadium which dissolved in seawater with extremely low concentration has been carried out at the offing of Mutsu establishment to evaluate the adsorption performance of adsorbent synthesized by radiation-induced graft-polymerization. The significant metals of uranium and vanadium eluted from the adsorbent which was soaked in the real sea were adsorbed onto the conventional chelate resin. The chelate resin which adsorbed the metals was packed in a plastic (PVC) column and further put in a cylindrical stainless transport container. This container was transported to the facility for separation and purification by a truck for the exclusive loading. Then the recovers metals were purified there. The recovered metals contained the uranium of 150g (1.92 MBq) and less in one recovery experiment. The maximum concentration is 60 Bq/g when the uranium is adsorbed on the chelate resin. Transport of recovered metals can be treated as general substance since these amount and concentration are out of legal control. However, the recovered metals were transported in conformity to L type Transport as a voluntary regulation. Though there is no requirements of structural strength for L type package legally, the structural strength of container was designed on that of IP-2 type which is higher transport grade than L type to take its safety measure. Its strength analysis proved the safety under general transport process. The transport was based on the plan made in advance. (author)

  8. f-Element Ion Chelation in Highly Basic Media

    International Nuclear Information System (INIS)

    Paine, R.T.

    2000-01-01

    A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelators for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

  9. Colour interceptions, thermal stability and surface morphology of polyester metal complexes

    International Nuclear Information System (INIS)

    Zohdy, M.H.

    2005-01-01

    Chelating copolymers via grafting of acrylic acid (AAc) and acrylamide (AAm/AAc) comonomer mixture onto polyester micro fiber fabrics (PETMF) using gamma-radiation technique were prepared. The prepared graft chains (PETMF-g-AAc) and (PETMF-g-PAAc/PAAm) acted as chelating sites for some selected transition metal ions. The prepared graft copolymers and their metal complexes were characterized using thermogravimetric analysis (TGA), colour parameters and surface morphology measurements. The colour interception and strength measurements showed that the metal complexation is homogeneously distributed. The results showed that the thermal stability of PETMF was improved after graft copolymerization and metal complexes. Moreover, the degree of grafting enhanced the thermal stability values of the grafted and complexed copolymers up to 25% of magnitude, on the other hand the activation energy of the grafted-copolymer with acrylic acid increased up to 80%. The SEM observation gives further supports to the homogenous distribution of grafting and metal complexation

  10. The Extracellular Domain of Human High Affinity Copper Transporter (hNdCTR1, Synthesized by E. coli Cells, Chelates Silver and Copper Ions In Vivo

    Directory of Open Access Journals (Sweden)

    Tatiana P. Sankova

    2017-11-01

    Full Text Available There is much interest in effective copper chelators to correct copper dyshomeostasis in neurodegenerative and oncological diseases. In this study, a recombinant fusion protein for expression in Escherichia coli cells was constructed from glutathione-S-transferase (GST and the N-terminal domain (ectodomain of human high affinity copper transporter CTR1 (hNdCTR1, which has three metal-bound motifs. Several biological properties of the GST-hNdCTR1 fusion protein were assessed. It was demonstrated that in cells, the protein was prone to oligomerization, formed inclusion bodies and displayed no toxicity. Treatment of E. coli cells with copper and silver ions reduced cell viability in a dose- and time-dependent manner. Cells expressing GST-hNdCTR1 protein demonstrated resistance to the metal treatments. These cells accumulated silver ions and formed nanoparticles that contained AgCl and metallic silver. In this bacterial population, filamentous bacteria with a length of about 10 µm were often observed. The possibility for the fusion protein carrying extracellular metal binding motifs to integrate into the cell’s copper metabolism and its chelating properties are discussed.

  11. Effects of zinc supplementation and zinc chelation on in vitro β-cell function in INS-1E cells

    DEFF Research Database (Denmark)

    Nygaard, Sanne Bjørn; Larsen, Agnete; Knuhtsen, Astrid

    2014-01-01

    BACKGROUND: Zinc is essential for the activities of pancreatic β-cells, especially insulin storage and secretion. Insulin secretion leads to co-release of zinc which contributes to the paracrine communication in the pancreatic islets. Zinc-transporting proteins (zinc-regulated transporter, iron......-regulated transporter-like proteins [ZIPs] and zinc transporters [ZnTs]) and metal-buffering proteins (metallothioneins, MTs) tightly regulate intracellular zinc homeostasis. The present study investigated how modulation of cellular zinc availability affects β-cell function using INS-1E cells. RESULTS: Using INS-1E...... cells, we found that zinc supplementation and zinc chelation had significant effects on insulin content and insulin secretion. Supplemental zinc within the physiological concentration range induced insulin secretion. Insulin content was reduced by zinc chelation with N,N,N',N-tektrakis(2-pyridylmethyl...

  12. Thermometric studies on the Fe(III)-EDTA chelate.

    Science.gov (United States)

    Dot, K

    1978-02-01

    A DeltaH of -11.5 +/- 0.5 kJ/mole has been determined for the formation of the Fe(III)-EDTA chelate at 25.0 degrees and mu = 0.1(= [HClO(4)] + [NaClO(4)]) by a direct thermometric titration procedure. The entropy change, DeltaS, has been calculated to be 440 J.mole(-1) .deg(-1) by combining the result of the heat measurements with the free energy change obtained from the stability constant previously determined. A relationship between the DeltaS values and the standard partial molal entropies of the tervalent metal ions is discussed. In addition, conditions for the thermometric titration of Fe(III) with NA(4)EDTA at room temperature have been investigated. Iron(III) can be determined in the presence of fairly large amounts of phosphate, Cr(III), Mn(II) and Al(III).

  13. N-Dansyl-N`-ethylthiourea for the fluorometric detection of heavy metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, M.; Sandor, M. [Technische Univ. Muenchen, Garching (Germany). Anorganisch-Chemisches Inst.

    1996-11-01

    N-Dansyl-N`-ethylthiourea (DET) forms fluorescent chelates with a large number of heavy metal ions. The influence of the pH-value on the luminescence of DET and its metal chelates was investigated. The addition of Cu(II) to DET causes a bathochromic shift of the emission maximum, which is linearly dependent on the Cu(II) concentration. Low detection limits and a wide linear range of detection are achieved by HPLC using RP 18 columns as stationary phase. Also presented are first measurements of fluorescence decay times of the ligand as well as some complexes. (orig.) With 5 figs., 3 tabs.

  14. Real-world healthcare utilization in asthma patients using albuterol sulfate inhalation aerosol (ProAir® HFA with and without integrated dose counters

    Directory of Open Access Journals (Sweden)

    Kerwin EM

    2017-05-01

    Full Text Available Edward M Kerwin,1 Thomas J Ferro,2 Rinat Ariely,3 Debra E Irwin,4 Ruchir Parikh3 1Clinical Trials Division, Clinical Research Institute of Southern Oregon, PC, Medford, OR, 2Global Medical Affairs, 3Global Health Economics and Outcome Research, Teva Pharmaceuticals, Frazer, PA, 4Outcomes Research, Truven Health Analytics, Durham, NC, USA Background: Accurate tracking of the administered dose of asthma rescue inhalers is critical for optimal disease management and is related to reductions in rates of unscheduled health care utilization in asthma patients. There are few published data on the real-world impact of rescue inhalers with integrated dose counters (IDCs on health care resource utilization (HRU for asthma patients. This study evaluates HRU among users of ProAir® hydrofluoroalkane (HFA (albuterol sulfate inhalation aerosol, with IDC versus without IDC, in asthma patients.Methods: This was a retrospective administrative claims study of asthma patients receiving a new prescription for albuterol inhalation aerosol without IDC during 2 years (January 2011–December 2012 or with IDC during the first full year after IDC implementation in the USA (July 2013–July 2014. Six months of continuous enrollment with medical and prescription drug benefits were required before and after the first prescription during the study period. Data on respiratory-related hospitalizations and emergency department (ED visits were collected during the follow-up period.Results: A total of 135,305 (32% patients used albuterol inhalation aerosol with IDC, and 287,243 (68% patients received albuterol inhalation aerosol without IDC. After adjusting for baseline confounding factors, the odds ratio (OR for experiencing a respiratory-related hospitalization (OR=0.92; 95% confidence interval [CI] 0.88–0.96 or ED visit (OR=0.92; 95% CI 0.90–0.94 was significantly lower among patients using albuterol inhalation aerosol with IDC versus without IDC.Conclusion: In a real

  15. Labelling of bacteria with indium chelates

    International Nuclear Information System (INIS)

    Kleinert, P.; Pfister, W.; Endert, G.; Sproessig, M.

    1985-01-01

    The indium chelates were prepared by reaction of radioactive indiumchloride with 10 μg oxine, 15 μg tropolone and 3 mg acetylacetone, resp. The formed chelates have been incubated with 10 9 germs/ml for 5 minutes, with labelling outputs from 90 to 95%. Both gram-positive (Streptococcus, Staphylococcus) and gram-negative bacteria (Escherichia coli) can be labelled. The reproductive capacity of the bacteria was not impaired. The application of indium labelled bacteria allows to show the distribution of microorganisms within the living organism and to investigate problems of bacterial adherence. (author)

  16. Decontamination of soils polluted with heavy metals using plants as determined by nuclear technique

    International Nuclear Information System (INIS)

    Lotfy, S.M

    2010-01-01

    The objectives of this work were three folds. First, to study the mobility and fate of heavy metals in two polluted sites (Mostorud soil, irrigated with contaminated water for more than 30 years and El-Gabal EL-Asfar soil, subjected to sewage effluent irrigation for more than 50 years) utilizing a modified tessier's sequential extraction procedure to evaluate the effect of total metal concentrations on metal partitioning into different fractions. Second, to evaluate the efficiency of some plant species (sunflower, cotton, penakium, Napier grass, and Squash) to extract heavy metals out of polluted soils. Third, to enhance the phyto-extraction of heavy metals by sunflower plant using some chemical chelators (citric acids, EDTA, and Ammonium nitrate) in order to improve the remediation of pollutants as well as to protect soil quality.It was observed that the distribution of heavy metals in various chemical fractions depends on the total heavy metals content. The distribution of heavy metals forms in the studied soils was in the following decreasing order: residual > Fe-Mn oxides > carbonates > organic > exchangeable > water soluble.Either higher metal accumulation in shoots or enhanced metal accumulation in roots was mainly due to improved phyto-extraction or rhizo-filtration efficiency, respectively. Heavy metals accumulation in shoots and roots of the investigated plant species was as follow: sunflower > cotton > penakium > Napier grass > Squash with a lower order of magnitude. Sunflower showed superiority for heavy metals extraction.Application of chemical chelators (soil amendments) enhanced the phyto-extraction efficiency of heavy metals by sunflower in both Mostorud and El-Gabal El-Asfar soils. Citric acid enhanced metals accumulation in shoots and roots more than EDTA and ammonium nitrate. Citric acid with rate of 20 m mole/kg soil was the best chelators to enhance phyto- extraction of heavy metals by sunflower.

  17. Traversing the Links between Heavy Metal Stress and Plant Signaling

    Science.gov (United States)

    Jalmi, Siddhi K.; Bhagat, Prakash K.; Verma, Deepanjali; Noryang, Stanzin; Tayyeba, Sumaira; Singh, Kirti; Sharma, Deepika; Sinha, Alok K.

    2018-01-01

    Plants confront multifarious environmental stresses widely divided into abiotic and biotic stresses, of which heavy metal stress represents one of the most damaging abiotic stresses. Heavy metals cause toxicity by targeting crucial molecules and vital processes in the plant cell. One of the approaches by which heavy metals act in plants is by over production of reactive oxygen species (ROS) either directly or indirectly. Plants act against such overdose of metal in the environment by boosting the defense responses like metal chelation, sequestration into vacuole, regulation of metal intake by transporters, and intensification of antioxidative mechanisms. This response shown by plants is the result of intricate signaling networks functioning in the cell in order to transmit the extracellular stimuli into an intracellular response. The crucial signaling components involved are calcium signaling, hormone signaling, and mitogen activated protein kinase (MAPK) signaling that are discussed in this review. Apart from signaling components other regulators like microRNAs and transcription factors also have a major contribution in regulating heavy metal stress. This review demonstrates the key role of MAPKs in synchronously controlling the other signaling components and regulators in metal stress. Further, attempts have been made to focus on metal transporters and chelators that are regulated by MAPK signaling. PMID:29459874

  18. Review of actinide decorporation with chelating agents

    Energy Technology Data Exchange (ETDEWEB)

    Ansoborlo, E. [CEA Valrho, Dir. de l' Energie Nucleaire (DEN/DRCP/CETAMA), 30 - Marcoule (France); Amekraz, B.; Moulin, Ch. [CEA Saclay, Dept. de Physico-Chimie (DEN/DPC/SECR), 91 - Gif sur Yvette (France); Moulin, V. [CEA Saclay, Dir. du Developpement et de l' Innovation Nucleares (DEN/DDIN/MR), 91 - Gif Sur Yvette (France); Taran, F. [CEA Saclay (DSV/DBJC/SMMCB), 91 - Gif-sur-Yvette (France); Bailly, Th.; Burgada, R. [Centre National de la Recherche Scientifique (CNRS/LCSB/UMR 7033), 93 - Bobigny (France); Henge-Napoli, M.H. [CEA Valrho, Site de Marcoule (INSTN), 30 (France); Jeanson, A.; Den Auwer, Ch.; Bonin, L.; Moisy, Ph. [CEA Valrho, Dir. de l' Energie Nucleaire (DEN/DRCP/SCPS), 30 - Marcoule (France)

    2007-10-15

    In case of accidental release of radionuclides in a nuclear facility or in the environment, internal contamination (inhalation, ingestion or wound) with actinides represents a severe health risk to human beings. It is therefore important to provide effective chelation therapy or decorporation to reduce acute radiation damage, chemical toxicity, and late radiation effects. Speciation governs bioavailability and toxicity of elements and it is a prerequisite tool for the design and success of new ligands or chelating agents. The purpose of this review is to present the state-of-the-art of actinide decorporation within biological media, to recall briefly actinide metabolism, to list the basic constraints of actinide-ligand for development, to describe main tools developed and used for decorporation studies, to review mainly the chelating agents tested for actinides, and finally to conclude on the future trends in this field. (authors)

  19. Determination of elemental composition of metals using ambient organic mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Shiea, Christopher [Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, 100 Shih-Chuan 1st Rd, Kaohsiung 807, Taiwan (China); Huang, Yeou-Lih [Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, 100 Shih-Chuan 1st Rd, Kaohsiung 807, Taiwan (China); Department of Chemistry, National Sun Yat-Sen University, 70 Lien-Hai Rd, Kaohsiung 804, Taiwan (China); Cheng, Sy-Chyi; Chen, Yi-Lun [Department of Chemistry, National Sun Yat-Sen University, 70 Lien-Hai Rd, Kaohsiung 804, Taiwan (China); Shiea, Jentaie, E-mail: jetea@mail.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, 70 Lien-Hai Rd, Kaohsiung 804, Taiwan (China); Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Rd, Kaohsiung 807, Taiwan (China)

    2017-05-22

    Conventional inorganic mass spectrometric (MS) analysis of metals can require time-consuming and tedious sample preparation. We thus report the novel and direct characterization of metals in solid samples using an organic MS technique known as electrospray laser desorption ionization mass spectrometry (ELDI/MS). No sample pretreatment was needed, and results were rapidly obtained due to the ambient and laser-based nature of ELDI/MS. Metals from samples were desorbed and ionized by laser irradiation, after which they reacted with EDTA and then post-ionized and detected as metal-EDTA complexes. Aluminum, copper, iron, lead, nickel, and zinc from plates, foils, and coins were characterized in seconds. This study demonstrates that an ESI/MS system can be easily modified to analyze metal elements in solids by involving a chelating agent, indicating a potentially promising development in MS towards the analysis of metals using organic MS. - Highlights: • “Organic MS” was utilized as “inorganic MS” to detect metal ions in solid samples. • Element ions desorbed by laser irradiation rapidly reacted with a chelating reagent before they were detected by MS. • Elemental composition of metals was determined by this “Organic MS” method.

  20. Determination of elemental composition of metals using ambient organic mass spectrometry

    International Nuclear Information System (INIS)

    Shiea, Christopher; Huang, Yeou-Lih; Cheng, Sy-Chyi; Chen, Yi-Lun; Shiea, Jentaie

    2017-01-01

    Conventional inorganic mass spectrometric (MS) analysis of metals can require time-consuming and tedious sample preparation. We thus report the novel and direct characterization of metals in solid samples using an organic MS technique known as electrospray laser desorption ionization mass spectrometry (ELDI/MS). No sample pretreatment was needed, and results were rapidly obtained due to the ambient and laser-based nature of ELDI/MS. Metals from samples were desorbed and ionized by laser irradiation, after which they reacted with EDTA and then post-ionized and detected as metal-EDTA complexes. Aluminum, copper, iron, lead, nickel, and zinc from plates, foils, and coins were characterized in seconds. This study demonstrates that an ESI/MS system can be easily modified to analyze metal elements in solids by involving a chelating agent, indicating a potentially promising development in MS towards the analysis of metals using organic MS. - Highlights: • “Organic MS” was utilized as “inorganic MS” to detect metal ions in solid samples. • Element ions desorbed by laser irradiation rapidly reacted with a chelating reagent before they were detected by MS. • Elemental composition of metals was determined by this “Organic MS” method.

  1. Binary and ternary chelates of Sc(III), Y(III) and La(III) with ethylenediamine tetraacetic acid as primary ligand and substituted salicylic acids as secondary ligands

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, A K; Chandra, M; Agarwala, B V; Dey, A K [Allahabad Univ. (India). Chemical Labs.

    1980-02-01

    Study of ternary complex formation of several tripositive metal ions viz. Sc(III), Y(III) and La(III) with ethylenediamine tetraacetic acid (EDTA) as a primary ligand and 5-chlorosalicylic acid (CSA) or 3,5-dibromosalicylic acid (DBSA) as secondary ligands by pH-metric titration technique is reported. The stability order of metal chelates with respect to ligands is observed to be DBSA>CSA and with respect to metal ions Sc(III)>Y(III)>La(III).

  2. Radiopharmaceutical chelates and method of external imaging

    International Nuclear Information System (INIS)

    1976-01-01

    The preparation of the following chemicals is described: chelates of technetium-99m, cobalt-57, gallium-67, gallium-68, indium-111 or indium-113m and a substituted iminodiacetic acid or an 8-hydroxyquinoline useful as a radiopharmaceutical external imaging agent. The compounds described are suitable for intravenous injection, have an excellent in vivo stability and are good organ seekers. Tin(II) choride or other tin(II) compounds are used as chelating agents

  3. Nanoscale orientation and lateral organization of chimeric metal-binding green fluorescent protein on lipid membrane determined by epifluorescence and atomic force microscopy

    International Nuclear Information System (INIS)

    Prachayasittikul, Virapong; Isarankura Na Ayudhya, Chartchalerm; Tantimongcolwat, Tanawut; Galla, Hans-Joachim

    2005-01-01

    Epifluorescence microscopy as well as atomic force microscopy was successfully applied to explore the orientation and lateral organization of a group of chimeric green fluorescent proteins (GFPs) on lipid membrane. Incorporation of the chimeric GFP carrying Cd-binding region (His6CdBP4GFP) to the fluid phase of DPPC monolayer resulted in a strong fluorescence intensity at the air-water interface. Meanwhile, non-specific adsorption of the GFP having hexahistidine (His6GFP) led to the perturbation of the protein structure in which very low fluorescence was observed. Specific binding of both of the chimeric GFPs to immobilized zinc ions underneath the metal-chelating lipid membrane was revealed. This specific binding could be reversibly controlled by addition of metal ions or metal chelator. Binding of the chimeric GFPs to the metal-chelating lipid membrane was proven to be the end-on orientation while the side-on adsorption was contrarily noted in the absence of metal ions. Increase of lateral mobility owing to the fluidization effect on the chelating lipid membrane subsequently facilitated crystal formation. All these findings have opened up a potential approach for a specific orientation of immobilization of protein at the membrane interface. This could have accounted for a better opportunity of sensor development

  4. Exploiting the Metal-Chelating Properties of the Drug Cargo for In Vivo Positron Emission Tomography Imaging of Liposomal Nanomedicines

    DEFF Research Database (Denmark)

    Edmonds, Scott; Volpe, Alessia; Shmeeda, Hilary

    2016-01-01

    of a radiolabeled stealth liposomal nanomedicine containing alendronate that shows high uptake in primary tumors and metastatic organs. The versatility, efficiency, simplicity, and GMP compatibility of this method may enable submicrodosing imaging studies of liposomal nanomedicines containing chelating drugs...

  5. CARDIAC FUNCTION AND IRON CHELATION IN THALASSEMIA MAJOR AND INTERMEDIA: A REVIEW OF THE UNDERLYING PATHOPHYSIOLOGY AND APPROACH TO CHELATION MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Athanasios Aessopos

    2009-07-01

    Full Text Available Heart disease is the leading cause of mortality and one of the main causes of morbidity in beta-thalassemia. Patients with homozygous thalassemia may have either a severe phenotype which is usually transfusion dependent or a milder form that is thalassemia intermedia.  The two main factors that determine cardiac disease in homozygous β thalassemia are the high output state that results from chronic tissue hypoxia, hypoxia-induced compensatory reactions and iron overload.  The high output state playing a major role in thalassaemia intermedia and the iron load being more significant in the major form. Arrhythmias, vascular involvement that leads to an increased pulmonary vascular resistance and an increased systemic vascular stiffness and valvular abnormalities also contribute to the cardiac dysfunction in varying degrees according to the severity of the phenotype.  Endocrine abnormalities, infections, renal function and medications can also play a role in the overall cardiac function.  For thalassaemia major, regular and adequate blood transfusions and iron chelation therapy are the mainstays of management. The approach to thalassaemia intermedia, today, is aimed at monitoring for complications and initiating, timely, regular transfusions and/or iron chelation therapy.  Once the patients are on transfusions, then they should be managed in the same way as the thalassaemia major patients.  If cardiac manifestations of dysfunction are present in either form of thalassaemia, high pre transfusion Hb levels need to be maintained in order to reduce cardiac output and appropriate intensive chelation therapy needs to be instituted.  In general recommendations on chelation, today, are usually made according to the Cardiac Magnetic Resonance findings, if available.  With the advances in the latter technology and the ability to tailor chelation therapy according to the MRI findings as well as the availability of three iron chelators, together with

  6. Phenolic aminocarboxylic acids - new chelating agents for modifying gallium-67 biodistribution

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, F.C.; Maddalena, D.J. (Australian Atomic Energy Commission Research Establishment, Lucas Heights)

    The chelating agents EDDHA and HBED were synthesised with carboxyl or sulphonyl groups in the phenolic ring to favour urinary excretion on complexing with gallium. Carboxyl EDDMA was administered to tumor-bearing rats, and its concentration in the tumours and other tissues determined by scintigraphic imaging. The chelating agents increase tumour to blood ratios by chelating gallium in vivo.

  7. Combinational chelation therapy abrogates lead-induced neurodegeneration in rats

    International Nuclear Information System (INIS)

    Pachauri, Vidhu; Saxena, Geetu; Mehta, Ashish; Mishra, Deepshikha; Flora, Swaran J.S.

    2009-01-01

    Lead, a ubiquitous and potent neurotoxicant causes oxidative stress which leads to numerous neurobehavioral and physiological alterations. The ability of lead to bind sulfhydryl groups or compete with calcium could be one of the reasons for its debilitating effects. In the present study, we addressed: i) if chelation therapy could circumvent the altered oxidative stress and prevent neuronal apoptosis in chronic lead-intoxicated rats, ii) whether chelation therapy could reverse biochemical and behavioral changes, and iii) if mono or combinational therapy with captopril (an antioxidant) and thiol chelating agents (DMSA/MiADMSA) is more effective than individual thiol chelator in lead-exposed rats. Results indicated that lead caused a significant increase in reactive oxygen species, nitric oxide, and intracellular free calcium levels along with altered behavioral abnormalities in locomotor activity, exploratory behavior, learning, and memory that were supported by changes in neurotransmitter levels. A fall in membrane potential, release of cytochrome c, and DNA damage indicated mitochondrial-dependent apoptosis. Most of these alterations showed significant recovery following combined therapy with captopril with MiADMSA and to a smaller extend with captopril + DMSA over monotherapy with these chelators. It could be concluded from our present results that co-administration of a potent antioxidant (like captopril) might be a better treatment protocol than monotherapy to counter lead-induced oxidative stress. The major highlight of the work is an interesting experimental evidence of the efficacy of combinational therapy using an antioxidant with a thiol chelator in reversing neurological dystrophy caused due to chronic lead exposure in rats.

  8. The effects of repeated parenteral administration of chelating agents on the distribution and excretion of uranium

    International Nuclear Information System (INIS)

    Domingo, J.L.; Ortega, A.; Llobet, J.M.; Paternain, J.L.; Corbella, J.

    1989-01-01

    The effects of repeated ip administration of gallic acid, 4,5-dihydroxy-1,3-benzenedisulfonic acid (Tiron), diethylenetriaminepentaacetic acid (DTPA), and 5-aminosalicylic acid (5-AS) on the distribution and excretion of uranium were assessed in male Swiss mice. Only Tiron significantly increased the amount of uranium excreted into urine and feces. A significant decrease in the concentration of uranium in liver, spleen and bone was observed after administration of Tiron, whereas injection of gallic acid or DTPA resulted in a significant decrease in the concentration of the metal in the liver. The results show that Tiron was consistently the most effective chelator of those tested in the treatment of uranium poisoning after repeated daily administration of the metal

  9. Moessbauer and EPR studies on iron-dihydroxybenzoic acid and iron-itoic acid chelate complexes

    International Nuclear Information System (INIS)

    Bagyinka, Cs.; Horvath, L.I.; Keszthelyi, L.

    1984-01-01

    Low molecular weight iron-dihydroxybenzoic acid and iron-itoic acid complexes were investigated by Moessbauer and EPR spectroscopy. In strong acidic medium the iron is chelated in high spin ferrous form. By varying the pH of the medium a (S=2)Fesup(2+)→(S=5/2)Fesup(3+) transition was found with a midpoint pH value of 4. From the g'-tensor anisotropy it is concluded that the metal atom is coordinated by six oxygen atoms in rhombically distorted octahedral configuration. The biological significance of these structural data is briefly discussed. (author)

  10. Rates of cuticular penetration of chelated Fe(III): role of humidity, concentration, adjuvants, temperature, and type of chelate.

    Science.gov (United States)

    Schönherr, Jörg; Fernández, Victoria; Schreiber, Lukas

    2005-06-01

    Time courses of cuticular penetration of FeCl3 and Fe(III) complexes of citric acid, EDTA, EDDHA (Sequestrene 138Fe), imidodisuccinic acid (IDHA), and ligninsulfonic acid (Natrel) were studied using astomatous cuticular membranes (CMs) isolated from Populus x canescens leaves. At 100% relative humidity, the Fe(III) chelates disappeared exponentially with time from the surface of the CMs; that is, penetration was a first-order process that can be described using rate constants or half-times of penetration (t(1/2)). Half-times ranged from 20 to 30 h. At 90% humidity, penetration rates were insignificant with the exception of Natrel, for which t(1/2) amounted to 58 h. Rate constants were independent of temperature (15, 25, and 35 degrees C). Permeability decreased with increasing Fe chelate concentration (IDHA and EDTA). At 100% humidity, half-times measured with FeIDHA were 11 h (2 mmol L(-1)), 17 h (10 mmol L(-1)) and 36 h (20 mmol L(-1)), respectively. In the presence of FeEDTA, penetration of CaCl2 was slowed greatly. Half-times for penetration of CaCl2, which were 1.9 h in the absence of FeEDTA, rose to 3.12 h in the presence of an equimolar concentration of EDTA and 13.3 h when the FeEDTA concentration was doubled. Hence, Fe chelates reduced permeability of CMs to CaCl2 and to the Fe chelates themselves. It is suggested that Fe chelates reduced the size of aqueous pores. This view is supported by the fact that rate constants for calcium salts were about 5 times higher than for Fe chelates with the same molecular weights. Adding Tween 20 (5 g L(-1)) as a humectant did not increase permeability to FeIDHA at 90% humidity and below, while addition of glycine betaine did. Penetration of FeCl3 applied at 5 g L(-1) (pH 1.5) was not a first order process as rate constants decreased rapidly with time. Only 2% of the dose penetrated during the first 2 h and less than that in the subsequent 8 h. Recovery was only 70%. This was attributed to the formation of insoluble Fe

  11. Novel bis-(−)-nor-meptazinol derivatives act as dual binding site AChE inhibitors with metal-complexing property

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Wei [Department of Medicinal Chemistry, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 200032 (China); NPFPC Key Laboratory of Contraceptives and Devices, Shanghai Institute of Planned Parenthood Research, 2140 Xietu Road, Shanghai 200032 (China); Li, Juan [Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, 280 South Chongqing Road, Shanghai 200025 (China); Qiu, Zhuibai [Department of Medicinal Chemistry, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 200032 (China); Xia, Zheng [Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, 280 South Chongqing Road, Shanghai 200025 (China); Li, Wei [Department of Medicinal Chemistry, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 200032 (China); Yu, Lining; Chen, Hailin; Chen, Jianxing [NPFPC Key Laboratory of Contraceptives and Devices, Shanghai Institute of Planned Parenthood Research, 2140 Xietu Road, Shanghai 200032 (China); Chen, Yan; Hu, Zhuqin; Zhou, Wei; Shao, Biyun; Cui, Yongyao [Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, 280 South Chongqing Road, Shanghai 200025 (China); Xie, Qiong, E-mail: xiejoanxq@gmail.com [Department of Medicinal Chemistry, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 200032 (China); Chen, Hongzhuan, E-mail: yaoli@shsmu.edu.cn [Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, 280 South Chongqing Road, Shanghai 200025 (China)

    2012-10-01

    The strategy of dual binding site acetylcholinesterase (AChE) inhibition along with metal chelation may represent a promising direction for multi-targeted interventions in the pathophysiological processes of Alzheimer's disease (AD). In the present study, two derivatives (ZLA and ZLB) of a potent dual binding site AChE inhibitor bis-(−)-nor-meptazinol (bis-MEP) were designed and synthesized by introducing metal chelating pharmacophores into the middle chain of bis-MEP. They could inhibit human AChE activity with IC{sub 50} values of 9.63 μM (for ZLA) and 8.64 μM (for ZLB), and prevent AChE-induced amyloid-β (Aβ) aggregation with IC{sub 50} values of 49.1 μM (for ZLA) and 55.3 μM (for ZLB). In parallel, molecular docking analysis showed that they are capable of interacting with both the catalytic and peripheral anionic sites of AChE. Furthermore, they exhibited abilities to complex metal ions such as Cu(II) and Zn(II), and inhibit Aβ aggregation triggered by these metals. Collectively, these results suggest that ZLA and ZLB may act as dual binding site AChEIs with metal-chelating potency, and may be potential leads of value for further study on disease-modifying treatment of AD. -- Highlights: ► Two novel bis-(−)-nor-meptazinol derivatives are designed and synthesized. ► ZLA and ZLB may act as dual binding site AChEIs with metal-chelating potency. ► They are potential leads for disease-modifying treatment of Alzheimer's disease.

  12. Novel bis-(−)-nor-meptazinol derivatives act as dual binding site AChE inhibitors with metal-complexing property

    International Nuclear Information System (INIS)

    Zheng, Wei; Li, Juan; Qiu, Zhuibai; Xia, Zheng; Li, Wei; Yu, Lining; Chen, Hailin; Chen, Jianxing; Chen, Yan; Hu, Zhuqin; Zhou, Wei; Shao, Biyun; Cui, Yongyao; Xie, Qiong; Chen, Hongzhuan

    2012-01-01

    The strategy of dual binding site acetylcholinesterase (AChE) inhibition along with metal chelation may represent a promising direction for multi-targeted interventions in the pathophysiological processes of Alzheimer's disease (AD). In the present study, two derivatives (ZLA and ZLB) of a potent dual binding site AChE inhibitor bis-(−)-nor-meptazinol (bis-MEP) were designed and synthesized by introducing metal chelating pharmacophores into the middle chain of bis-MEP. They could inhibit human AChE activity with IC 50 values of 9.63 μM (for ZLA) and 8.64 μM (for ZLB), and prevent AChE-induced amyloid-β (Aβ) aggregation with IC 50 values of 49.1 μM (for ZLA) and 55.3 μM (for ZLB). In parallel, molecular docking analysis showed that they are capable of interacting with both the catalytic and peripheral anionic sites of AChE. Furthermore, they exhibited abilities to complex metal ions such as Cu(II) and Zn(II), and inhibit Aβ aggregation triggered by these metals. Collectively, these results suggest that ZLA and ZLB may act as dual binding site AChEIs with metal-chelating potency, and may be potential leads of value for further study on disease-modifying treatment of AD. -- Highlights: ► Two novel bis-(−)-nor-meptazinol derivatives are designed and synthesized. ► ZLA and ZLB may act as dual binding site AChEIs with metal-chelating potency. ► They are potential leads for disease-modifying treatment of Alzheimer's disease.

  13. Modeling the chelation of As(III) in lewisite by dithiols using density functional theory and solvent-assisted proton exchange.

    Science.gov (United States)

    Harper, Lenora K; Bayse, Craig A

    2015-12-01

    Dithiols such as British anti-lewisite (BAL, rac-2,3-dimercaptopropanol) are an important class of antidotes for the blister agent lewisite (trans-2-chlorovinyldichloroarsine) and, more generally, are chelating agents for arsenic and other toxic metals. The reaction of the vicinal thiols of BAL with lewisite through the chelation of the As(III) center has been modeled using density functional theory (DFT) and solvent-assisted proton exchange (SAPE), a microsolvation method that uses a network of water molecules to mimic the role of bulk solvent in models of aqueous phase chemical reactions. The small activation barriers for the stepwise SN2-type nucleophilic attack of BAL on lewisite (0.7-4.9kcal/mol) are consistent with the favorable leaving group properties of the chloride and the affinity of As(III) for soft sulfur nucleophiles. Small, but insignificant, differences in activation barriers were found for the initial attack of the primary versus secondary thiol of BAL and the R vs S enantiomer. An examination of the relative stability of various dithiol-lewisite complexes shows that ethanedithiols like BAL form the most favorable chelation complexes because the angles formed in five-membered ring are most consistent with the hybridization of As(III). More obtuse S-As-S angles are required for larger chelate rings, but internal As⋯N or As⋯O interactions can enhance the stability of moderate-sized rings. The low barriers for lewisite detoxification by BAL and the greater stability of the chelation complexes of small dithiols are consistent with the rapid reversal of toxicity demonstrated in previously reported animal models. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Investigation of molecular mechanisms of action of chelating drugs on protein-lipid model membranes by X-ray fluorescence

    International Nuclear Information System (INIS)

    Novikova, N. N.; Zheludeva, S. I.; Koval'chuk, M. V.; Stepina, N. D.; Erko, A. I.; Yur'eva, E. A.

    2009-01-01

    Protein-lipid films based on the enzyme alkaline phosphatase were subjected to the action of chelating drugs, which are used for accelerating the removal of heavy metals from the human body, and the elemental composition of the resulting films was investigated. Total-reflection X-ray fluorescence measurements were performed at the Berlin Electron Storage Ring Company for Synchrotron Radiation (BESSY) in Germany. A comparative estimation of the protective effect of four drugs (EDTA, succimer, xydiphone, and mediphon) on membrane-bound enzymes damaged by lead ions was made. The changes in the elemental composition of the protein-lipid films caused by high doses of chelating drugs were investigated. It was shown that state-of-the-art X-ray techniques can, in principle, be used to develop new methods for the in vitro evaluation of the efficiency of drugs, providing differential data on their actions.

  15. Different photoluminescent properties of binary and ternary europium chelates doped in PMMA

    International Nuclear Information System (INIS)

    Liu Hongguo; Park, Seongtae; Jang, Kiwan; Zhang Wansong; Seo, Hyo-Jin; Lee, Yong-Ill

    2003-01-01

    Two kinds of europium-β-diketone chelates, binary Eu(DBM) 3 and ternary Eu(DBM) 3 phen were doped in poly(methyl methacrylate) (PMMA). These chelates show very different photoluminescent (PL) behaviors: the hypersensitive 5 D 0 → 7 F 2 emission bands of Eu(DBM) 3 phen change slightly with the molar ratios, while those of Eu(DBM) 3 change obviously and regularly with the molar ratios. The results of the luminescent lifetimes of 5 D 0 levels show that the binary chelate exists as two kinds of species in the doped systems, and the lifetimes and contents of each species change with the molar ratios, while the ternary chelate exists as one kind of species in the doped systems. X-ray diffraction (XRD) patterns of the binary chelate doped systems give some diffraction peaks that are different from those of pure chelate and change with the molar ratios, indicating new kinds of crystal structures formed, and consequently, the first coordination sphere of Eu 3+ ion changes; while those of the ternary chelate doped systems just show amorphous diffraction halos of the host, indicating that the ternary chelate exist in an amorphous state and disperse well in the host. The FTIR spectra of PMMA also change gradually with increasing the molar ratios of the doped two kinds of chelates, and the XRD patterns show that the amorphous halos of PMMA in the doped systems are different from those of pure PMMA and change with the molar ratios, too, suggesting the interaction between the guest and the host

  16. Effect of pH on the release of radionuclides and chelating agents from cement-solidified decontamination ion-exchange resins collected from operating nuclear power stations

    International Nuclear Information System (INIS)

    McIsaac, C.V.; Akers, D.W.; McConnell, J.W.

    1991-06-01

    Data are presented on the physical stability and leachability of radionuclides and chelating agents from cement-solidified decontamination ion-exchange resin wastes collected from two operating commercial light water reactors. Small-scale waste--form specimens collected during solidifications performed at the Brunswick Steam Electric Plant Unit 1 and at the James A. FitzPatrick Nuclear Power Station were leach-tested and subjected to compressive strength testing in accordance with the Nuclear Regulatory Commission's ''Technical Position on Waste Form'' (Revision 1). Samples of untreated resin waste collected from each solidification vessel before the solidification process were analyzed for concentrations of radionuclides, selected transition metals, and chelating agents to determine the quantities of these chemicals in the waste-form specimens. The chelating agents included oxalic, citric, and picolinic acids. In order to determine the effect of leachant chemical composition and pH on the stability and leachability of the waste forms, waste-form specimens were leached in various leachants. Results of this study indicate that differences in pH do not affect releases from cement-solidified decontamination ion-exchange resin waste forms, but that differences in leachant chemistry and the presence of chelating agents may affect the releases of radionuclides and chelating agents. Also, this study indicates that the cumulative releases of radionuclides and chelating agents are similar for waste- form specimens that decomposed and those that retained their general physical form. 36 refs., 60 figs., 28 tabs

  17. Phenolic aminocarboxylic acids - new chelating agents for modifying gallium-67 biodistribution

    International Nuclear Information System (INIS)

    Hunt, F.C.; Maddalena, D.J.

    1982-01-01

    The chelating agents EDDHA and HBED were synthesised with carboxyl or sulphonyl groups in the phenolic ring to favour urinary excretion on complexing with gallium. Carboxyl EDDMA was administered to tumor-bearing rats, and its concentration in the tumours and other tissues determined by scintigraphic imaging. The chelating agents increase tumour to blood ratios by chelating gallium in vivo. (U.K.)

  18. Antioxidant, Iron-chelating and Anti-glucosidase Activities of Typha ...

    African Journals Online (AJOL)

    Iron chelating activity was assessed using a ferrozine-based assay. Anti- glucosidase activity was determined using 4-nitrophenyl ... flavonoid (TF) content was determined based an aluminum chloride colorimetric assay [6]. TF content was ..... Dietary iron restriction or iron chelation protects from diabetes and loss of β-cell.

  19. Olivine-type cathode for rechargeable batteries: Role of chelating agents

    International Nuclear Information System (INIS)

    Kandhasamy, Sathiyaraj; Singh, Pritam; Thurgate, Stephen; Ionescu, Mihail; Appadoo, Dominique; Minakshi, Manickam

    2012-01-01

    Highlights: ► Olivine powder was synthesized by sol–gel method using a range of chelating agents. ► Role of chelating agents in olivine cathode was investigated for battery application. ► Battery was fabricated with olivine cathode, Zn anode and aqueous electrolyte. ► Synergetic effect of additives (CA + TEA + PVP) led to improved storage capacity. - Abstract: Olivine (LiCo 1/3 Mn 1/3 Ni 1/3 PO 4 ) powders were synthesized at 550–600 °C for 6 h in air by a sol–gel method using multiple chelating agents and used as a cathode material for rechargeable batteries. Range of chelating agents like a weak organic acid (citric acid – CA), emulsifier (triethanolamine – TEA) and non-ionic surfactant (polyvinylpyrrolidone – PVP) in sol–gel wet chemical synthesis were used. The dependence of the physicochemical properties of the olivine powders such as particle size, morphology, structural bonding and crystallinity on the chelating agent was extensively investigated. Among the chelating agents used, unique cycling behavior (75 mAh/g after 25 cycles) is observed for the PVP assisted olivine. This is due to volumetric change in trapped organic layer for first few cycles. The trapped organic species in the electrode–electrolyte interface enhances the rate of lithium ion diffusion with better capacity retention. In contrast, CA and TEA showed a gradual capacity fade of 30 and 38 mAh/g respectively after multiple cycles. The combination of all the three mixed chelating agents showed an excellent electrochemical behavior of 100 mAh/g after multiple cycles and the synergistic effect of these agents are discussed.

  20. The architecture of metal coordination groups in proteins.

    Science.gov (United States)

    Harding, Marjorie M

    2004-05-01

    A set of tables is presented and a survey given of the architecture of metal coordination groups in a representative set of protein structures from the Protein Data Bank [Bernstein et al. (1977), J. Mol. Biol. 112, 535-542; Berman et al. (2000), Nucleic Acids Res. 28, 235-242]. The structures have been determined to a resolution of 2.5 A or better; the metals considered are Ca, Mg, Mn, Fe, Cu, Zn, Na and K, with particular emphasis on Ca and Zn and the exclusion of haem groups and Fe/S clusters; the proteins are a representative set in which none has more than 30% sequence identity with any other. In them the metal is coordinated by several donor groups from different amino-acid residues in the protein chain and often also by water or other small molecules. The tables, for approximately 600 metal coordination groups, include information on the conformations of the protein chain in the region around the metal and reliability indicators. They illustrate the wide variety of coordination numbers, chelate-loop sizes and other properties and the different characteristics of different metals. They show that glycine has a particular significance in the position adjacent to a donor residue, especially in Ca coordination groups. They also show that metal coordination does not appear to lead to significant distortions of the torsion angles phi, psi from their normally allowed values. Very few metal coordination groups occur more than once in the representative set and when they do they are usually related in fold and function; they have similar but not necessarily identical conformations. However, individual chelate loops, for example Zn(-C-X-X'-C-), in which both cysteines are coordinated to Zn through S, and X and X' are any amino acids, are repeated frequently in many different and unrelated proteins. Not all chelate loops with the same composition have the same conformation, but for smaller loops there are usually one or two strongly preferred and well defined

  1. Multielement determination of trace metals in river water (certified reference material, JSAC 0301-1) by high efficiency nebulization ICP-MS after 100-fold preconcentration with a chelating resin-packed minicolumn

    International Nuclear Information System (INIS)

    Zhu, Yanbei; Hattori, Ryota; Fujimori, Eiji; Umemura, Tomonari; Haraguchi, Hiroki

    2005-01-01

    The determination of 34 trace metals in a river water certified reference material (CRM), i.e. JSAC 0301-1, which was issued by the Japan Society for Analytical Chemistry in January 2004, was performed by ICP-MS with a high efficiency nebulizer after preconcentration with a laboratory-made chelating resin-packed minicolumn, with which trace metals were concentrated 100-fold from 50 mL of a river water sample to 0.5 mL of the final analysis solution. Trace metals in JSAC 0301-1 were observed in the concentration range from 19 μg L -1 of Al to 0.000053 μg L -1 of Bi. It was found that most of the concentrations of trace metals, including rare earth elements (REEs), in JSAC 0301-1 were lower than those in JAC 0031, which was also a previously issued CRM prepared with water from the same river as that of JSAC 0301-1. The low concentrations of trace metals in JSAC 0301-1 might be attributed to the fact that there was heavy rain before collecting the original water sample to prepare the present CRM. Furthermore, the REE distribution patterns of JSAC 0301-1, JAC 0031 and the average values of river water samples in Japan were parallel to each other. These results indicate that the distributions of REEs in JSAC 0301-1 and JAC 0031 were the typical ones of river water samples in Japan. (author)

  2. Direct electrochemical sensing of glucose using glucose oxidase immobilized on functionalized carbon nanotubes via a novel metal chelate-based affinity method

    International Nuclear Information System (INIS)

    Tu, X.; Zhao, Y.; Luo, S.; Luo, X.; Feng, L.

    2012-01-01

    We report on a novel amperometric glassy carbon biosensing electrode for glucose. It is based on the immobilization of a highly sensitive glucose oxidase (GOx) by affinity interaction on carbon nanotubes (CNTs) functionalized with iminodiacetic acid and metal chelates. The new technique for immobilization is exploiting the affinity of Co(II) ions to the histidine and cysteine moieties on the surface of GOx. The direct electrochemistry of immobilized GOx revealed that the functionalized CNTs greatly improve the direct electron transfer between GOx and the surface of the electrode to give a pair of well-defined and almost reversible redox peaks and undergoes fast heterogeneous electron transfer with a rate constant (k s) of 0. 59 s -1 . The GOx immobilized in this way fully retained its activity for the oxidation of glucose. The resulting biosensor is capable of detecting glucose at levels as low as 0.01 mM, and has excellent operational stability (with no decrease in the activity of enzyme over a 10 days period). The method of immobilizing GOx is easy and also provides a model technique for potential use with other redox enzymes and proteins. (author)

  3. The iron-chelate transporter OsYSL9 plays a role in iron distribution in developing rice grains.

    Science.gov (United States)

    Senoura, Takeshi; Sakashita, Emi; Kobayashi, Takanori; Takahashi, Michiko; Aung, May Sann; Masuda, Hiroshi; Nakanishi, Hiromi; Nishizawa, Naoko K

    2017-11-01

    Rice OsYSL9 is a novel transporter for Fe(II)-nicotianamine and Fe(III)-deoxymugineic acid that is responsible for internal iron transport, especially from endosperm to embryo in developing seeds. Metal chelators are essential for safe and efficient metal translocation in plants. Graminaceous plants utilize specific ferric iron chelators, mugineic acid family phytosiderophores, to take up sparingly soluble iron from the soil. Yellow Stripe 1-Like (YSL) family transporters are responsible for transport of metal-phytosiderophores and structurally similar metal-nicotianamine complexes. Among the rice YSL family members (OsYSL) whose functions have not yet been clarified, OsYSL9 belongs to an uncharacterized subgroup containing highly conserved homologs in graminaceous species. In the present report, we showed that OsYSL9 localizes mainly to the plasma membrane and transports both iron(II)-nicotianamine and iron(III)-deoxymugineic acid into the cell. Expression of OsYSL9 was induced in the roots but repressed in the nonjuvenile leaves in response to iron deficiency. In iron-deficient roots, OsYSL9 was induced in the vascular cylinder but not in epidermal cells. Although OsYSL9-knockdown plants did not show a growth defect under iron-sufficient conditions, these plants were more sensitive to iron deficiency in the nonjuvenile stage compared with non-transgenic plants. At the grain-filling stage, OsYSL9 expression was strongly and transiently induced in the scutellum of the embryo and in endosperm cells surrounding the embryo. The iron concentration was decreased in embryos of OsYSL9-knockdown plants but was increased in residual parts of brown seeds. These results suggested that OsYSL9 is involved in iron translocation within plant parts and particularly iron translocation from endosperm to embryo in developing seeds.

  4. Oxidation of Phenol by Hydrogen Peroxide Catalyzed by Metal-Containing Poly(amidoxime Grafted Starch

    Directory of Open Access Journals (Sweden)

    Hany El-Hamshary

    2011-11-01

    Full Text Available Polyamidoxime chelating resin was obtained from polyacrylonitrile (PAN grafted starch. The nitrile groups of the starch-grafted polyacrylonitrile (St-g-PAN were converted into amidoximes by reaction with hydroxylamine under basic conditions. The synthesized graft copolymer and polyamidoxime were characterized by FTIR, TGA and elemental microanalysis. Metal chelation of the polyamidoxime resin with iron, copper and zinc has been studied. The produced metal-polyamidoxime polymer complexes were used as catalysts for the oxidation of phenol using H2O2 as oxidizing agent. The oxidation of phenol depends on the central metal ion present in the polyamidoxime complex. Reuse of M-polyamidoxime catalyst/H2O2 system showed a slight decrease in catalytic activities for all M-polyamidoxime catalysts.

  5. Extraction of metals and/or metalloids from acidic media using supercritical fluids and salts

    International Nuclear Information System (INIS)

    Wai, C.M.; Smart, N.G.; Lin, Y.

    1998-01-01

    A method is described for extracting metalloid and metal species from a solid or liquid material by exposing the material to a fluid solvent, particularly supercritical carbon dioxide, containing a chelating agent. The chelating agent forms chelates that are soluble in the fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent comprises a trialkyl phosphate, a triaryl phosphate, a trialkylphosphine oxide, a triarylphosphine oxide, or mixtures thereof. The method provides an environmentally benign process for removing contaminants from industrial waste. The method is particularly useful for extracting actinides from acidic solutions, and the process can be aided by the addition of nitrate salts. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process. 7 figs

  6. Extraction of metals and/or metalloids from acidic media using supercritical fluids and salts

    Science.gov (United States)

    Wai, Chien M.; Smart, Neil G.; Lin, Yuehe

    1998-01-01

    A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a fluid solvent, particularly supercritical carbon dioxide, containing a chelating agent is described. The chelating agent forms chelates that are soluble in the fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent comprises a trialkyl phosphate, a triaryl phosphate, a trialkylphosphine oxide, a triarylphosphine oxide, or mixtures thereof. The method provides an environmentally benign process for removing contaminants from industrial waste. The method is particularly useful for extracting actinides from acidic solutions, and the process can be aided by the addition of nitrate salts. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.

  7. The influence of functional groups on the permeation and distribution of antimycobacterial rhodamine chelators.

    Science.gov (United States)

    Moniz, T; Leite, A; Silva, T; Gameiro, P; Gomes, M S; de Castro, B; Rangel, M

    2017-10-01

    We formerly hypothesized a mechanism whereby the antimycobacterial efficiency of a set of rhodamine labelled iron chelators is improved via the rhodamine fluorophore which enhances the chelators' permeation properties through membranes. To validate our hypothesis in a cellular context and to understand the influence of the structure of the fluorophore on the chelator's uptake and distribution within macrophages we now report comparative confocal microscopy studies performed with a set of rhodamine labelled chelators. We identify the functional groups of the chelator's framework that favor uptake by macrophages and conclude that the antimycobacterial effect is strongly related with the capacity of the chelator to distribute within the host cell and its compartments, a property that is closely related with the chelators' ability to interact with membranes. The quantification of the chelators' interaction with membranes was assessed through measurement of the corresponding partition constants in liposomes. The overall results support that the compounds which are preferentially taken up are the most efficient antimycobacterial chelators and for that reason we infer that the biological activity is modulated by the structural features of the fluorophore. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Theoretical analysis of the influence of chelate-ring size and vicinal effects on electronic circular dichroism spectra of cobalt(III) EDDA-type complexes.

    Science.gov (United States)

    Wang, Ai; Wang, Yuekui; Jia, Jie; Feng, Lixia; Zhang, Chunxia; Liu, Linlin

    2013-06-20

    To assess the contributions of configurational and vicinal effects as well as chelate-ring size to rotational strengths, the geometries of a series of cobalt(III) complexes [Co(EDDA-type)(L)](±) with the tetradentate EDDA-type ligands, EDDA (ethylenediamine-N,N'-diacetate), DMEDDA (N,N'-dimethylethylenediamine-N,N'-diacetate), DEEDDA (N,N'-diethylethylenediamine-N,N'-diacetate), and a bidentate ancillary ligand L (L = ethylenediamine, oxalate, carbonate, (S)-alanine, and malonate) in aqueous solution have been optimized at the DFT/B3LYP/6-311++G(2d,p) level of theory. Based on the optimized geometries, the excitation energies and oscillator and rotational strengths have been calculated using the time-dependent density functional theory (TDDFT) method with the same functional and basis set. The calculated circular dichroism (CD) curves are in excellent agreement with the observed ones except for some small red or blue shifts in peak wavelengths. For the influence of chelate-ring size of the bidentate ligands on the CD intensities, a qualitative analysis together with the quantitative TDDFT calculation reveal that it depends on the symmetry of the cobalt-EDDA backbone. For the s-cis-isomers, the influence is negligible due to the perturbation is symmetric. For the uns-cis-isomers, the perturbation is unsymmetric. Since a small ring size means a large perturbation, this leads to the integral CD intensities decreasing with increasing the chelate ring size. The vicinal effects of asymmetric nitrogens incorporate both the substitutent effects and conformational relaxation effects, with the former being dominant. By analyzing the contributions of chiral arrays to rotational strengths, we found that the part of contributions dominated by the S-type chiral nitrogens could be considered as a good measure for the vicinal effects of chiral nitrogens. In addition, we found that the twist form (δ/λ) of the backbone ethylenediamine ring (E-ring) of the coordinated EDDA

  9. Iron chelators ICL670 and 311 inhibit HIV-1 transcription

    International Nuclear Information System (INIS)

    Debebe, Zufan; Ammosova, Tatyana; Jerebtsova, Marina; Kurantsin-Mills, Joseph; Niu, Xiaomei; Charles, Sharroya; Richardson, Des R.; Ray, Patricio E.; Gordeuk, Victor R.; Nekhai, Sergei

    2007-01-01

    HIV-1 replication is induced by an excess of iron and iron chelation by desferrioxamine (DFO) inhibits viral replication by reducing proliferation of infected cells. Treatment of cells with DFO and 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311) inhibit expression of proteins that regulate cell-cycle progression, including cycle-dependent kinase 2 (CDK2). Our recent studies showed that CDK2 participates in HIV-1 transcription and viral replication suggesting that inhibition of CDK2 by iron chelators might also affect HIV-1 transcription. Here we evaluated the effect of a clinically approved orally effective iron chelator, 4-[3,5-bis-(hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid (ICL670) and 311 on HIV-1 transcription. Both ICL670 and 311 inhibited Tat-induced HIV-1 transcription in CEM-T cells, 293T and HeLa cells. Neither ICL670 nor 311 induced cytotoxicity at concentrations that inhibited HIV-1 transcription. The chelators decreased cellular activity of CDK2 and reduced HIV-1 Tat phosphorylation by CDK2. Neither ICL670A or 311 decreased CDK9 protein level but significantly reduced association of CDK9 with cyclin T1 and reduced phosphorylation of Ser-2 residues of RNA polymerase II C-terminal domain. In conclusion, our findings add to the evidence that iron chelators can inhibit HIV-1 transcription by deregulating CDK2 and CDK9. Further consideration should be given to the development of iron chelators for future anti-retroviral therapeutics

  10. Interaction of chelating agents with cadmium in mice and rats

    International Nuclear Information System (INIS)

    Eybl, V.; Sykora, J.; Koutensky, J.; Caisova, D.; Schwartz, A.; Mertl, F.

    1984-01-01

    The influence of several chelating agents (CaDTPA, ZnDTPA, CaEDTA, ZnEDTA, DMSA, D-penicillamine and DMPS, DMP and DDC) on the acute toxicity of CdCl 2 and on the whole body retention and tissue distribution of cadmium after the IV application of /sup 115mCdCl 2 was compared in mice. The chelating agents were applied immediately after the application of cadmium. CaDTPA, ZnDTPA and DMSA appeared to be the most effective antidotes. However, DMSA increased the amount of cadmium retained in kidneys. The treatement of cadmium-poisoned mice with the combination of DMSA (IP) and ZnDTPA (SC) (all the compounds were injected in equimolar dose) decreased the toxicity of cadmium more than treatment with one chelating agents (given in a 2:1 dose). However, by studying the effect of these chelating agents and their combination application of the antidotes showed little or no improvement over the results obtained with the most effective of the individual components. In the urine of rats injected with CdCl 2 and treated with the chelating agents (CaDTPA, ZnDTPA, DMSA), the presence of cadmium complexes was demonstrated. The formation of mixed ligand chelates in vivo was not proved. Experiments in mice given a single injection of /sup 115m/Cd-labeled Cd complexes of DMPS, DMSA and DTPA showed a high retention of cadmium in the organisms after the IV application of CdDMPS and CdDMSA complexes

  11. Bone marrow and chelatable iron in patients with protein energy ...

    African Journals Online (AJOL)

    chelatable iron is present and is excreted in the urine of children with kwashiorkor ... venous blood sample was drawn for routine biochemical and haematological .... storage.l.1:m In response to chelation, the kwashiorkor children excrete large ...

  12. Effects of solvent and chelating agent on synthesis of solid oxide fuel cell perovskite, La0.8Sr0.2CrO3-δ

    International Nuclear Information System (INIS)

    Lee, Byoung I.; Gupta, Ravindra K.; Whang, Chin M.

    2008-01-01

    Effects of solvent and chelating agent on synthesis of La 0.8 Sr 0.2 CrO 3-δ perovskite are reported. Samples are synthesized using a solvent (ethylene glycol or 2-methoxyethanol) and a chelating agent (acetylacetone, citric acid or ethylene diamine tetraacetic acid) by polymeric-gel method, and characterized by X-ray diffractometry and Fourier-transform infrared spectroscopy. Citric acid to metal cations molar ratio (Rc) is varied for ethylene glycol-citric acid system. Samples are mainly orthorhombic perovskite. SrCrO 4 is appeared as a secondary phase and found to be the lowest for ethylene glycol-citric acid combination with Rc equal to 7. Crystallographic parameters of perovskite phase are determined and compared with those of LaCrO 3 . A mechanism employing a partial-charge model, chelating effect and solvent-cage effect is proposed to explain the results. Effect of sintering temperature on phase, relative density and morphology of samples prepared using ethylene glycol and citric acid (Rc = 7) is also reported

  13. N-acetylcysteine protects rats with chronic renal failure from gadolinium-chelate nephrotoxicity.

    Directory of Open Access Journals (Sweden)

    Leonardo Victor Barbosa Pereira

    Full Text Available The aim of this study was to evaluate the effect of Gd-chelate on renal function, iron parameters and oxidative stress in rats with CRF and a possible protective effect of the antioxidant N-Acetylcysteine (NAC. Male Wistar rats were submitted to 5/6 nephrectomy (Nx to induced CRF. An ionic-cyclic Gd (Gadoterate Meglumine was administrated (1.5 mM/KgBW, intravenously 21 days after Nx. Clearance studies were performed in 4 groups of anesthetized animals 48 hours following Gd- chelate administration: 1--Nx (n = 7; 2--Nx+NAC (n = 6; 3--Nx+Gd (n = 7; 4--Nx+NAC+Gd (4.8 g/L in drinking water, initiated 2 days before Gd-chelate administration and maintained during 4 days (n = 6. This group was compared with a control. We measured glomerular filtration rate, GFR (inulin clearance, ml/min/kg BW, proteinuria (mg/24 hs, serum iron (µg/dL; serum ferritin (ng/mL; transferrin saturation (%, TIBC (µg/dL and TBARS (nmles/ml. Normal rats treated with the same dose of Gd-chelate presented similar GFR and proteinuria when compared with normal controls, indicating that at this dose Gd-chelate is not nephrotoxic to normal rats. Gd-chelate administration to Nx-rats results in a decrease of GFR and increased proteinuria associated with a decrease in TIBC, elevation of ferritin serum levels, transferrin oversaturation and plasmatic TBARS compared with Nx-rats. The prophylactic treatment with NAC reversed the decrease in GFR and the increase in proteinuria and all alterations in iron parameters and TBARS induced by Gd-chelate. NAC administration to Nx rat did not modify the inulin clearance and iron kinetics, indicating that the ameliorating effect of NAC was specific to Gd-chelate. These results suggest that NAC can prevent Gd-chelate nephrotoxicity in patients with chronic renal failure.

  14. Chromatography of metal ions with a triazine chelating resin

    International Nuclear Information System (INIS)

    Wang, W.N.

    1979-05-01

    The synthesis, characterization, and some analytical applications of a new triazine resin are described. Separation of group IB, IIB, VIB, and VIIB metal ions from group VIII metal ions is achieved by this PDT-4 resin. Calcium(II) and magnesium(II) are taken up at pH = 6, 0.1 M acetate and are eluted at pH = 6, 0.1 M sodium nitrate. Copper(II) is retained at pH = 6, 0.1 M acetate and pH = 1 hydrochloric acid and is eluted subsequently by 5 M perchloric acid. Molybdenum(VI) is sorbed selectively from 0.1 N sulfuric acid or hydrochloric acid and is eluted in a tight band by 0.1 N sodium hydroxide. Numerous rapid column chromatographic separations are reported using this new resin, including analysis of NBS standard samples

  15. EDTA chelation therapy for cardiovascular disease: a systematic review

    Directory of Open Access Journals (Sweden)

    Wu Ping

    2005-11-01

    Full Text Available Abstract Background Numerous practitioners of both conventional and complementary and alternative medicine throughout North America and Europe claim that chelation therapy with EDTA is an effective means to both control and treat cardiovascular disease. These claims are controversial, and several randomized controlled trials have been completed dealing with this topic. To address this issue we conducted a systematic review to evaluate the best available evidence for the use of EDTA chelation therapy in the treatment of cardiovascular disease. Methods We conducted a systematic review of 7 databases from inception to May 2005. Hand searches were conducted in review articles and in any of the trials found. Experts in the field were contacted and registries of clinical trials were searched for unpublished data. To be included in the final systematic review, the studies had to be randomized controlled clinical trials. Results A total of seven articles were found assessing EDTA chelation for the treatment of cardiovascular disease. Two of these articles were subgroup analyses of one RCT that looked at different clinical outcomes. Of the remaining five studies, two smaller studies found a beneficial effect whereas the other three exhibited no benefit for cardiovascular disease from the use of EDTA chelation therapy. Adverse effects were rare but those of note included a few cases of hypocalcemia and a single case of increased creatinine in a patient on the EDTA intervention. Conclusion The best available evidence does not support the therapeutic use of EDTA chelation therapy in the treatment of cardiovascular disease. Although not considered to be a highly invasive or harmful therapy, it is possible that the use of EDTA chelation therapy in lieu of proven therapy may result in causing indirect harm to the patient.

  16. SYNTHESIS OF N- ACETONITRIL AND N- ETHYLAMINE- 3- HYDROXYPYRIDINONES AS IRON (III CHELATORS

    Directory of Open Access Journals (Sweden)

    L.A. SAGHAEI

    2000-12-01

    Full Text Available Background. The need of iron-chelating agents as orally active alternatives to desferal for the treatment of iron overload in thalassaemic patients, has stimulated considerable research efforts in the synthesis of new metal chelators. One of the member of hydroxypyridinones (2,3- dimethyl-3- hydroxypyridinones has so far received the most attention. This compound is rapidly glucuronidated into a non-chelating metabolite, which partly explains why high doses of the compound has to be used in order to achieve negative balance. This metabolic behavior has led the medicinal chemists to design compounds such as N-hydroxyalkyl derivatives which do not undergo extensive metabolism. The objective of the present work was to further synthesis and design new derivatives of hydroxypyridinones (N- acetonitril and N-ethylamine derivatives Methods. The synthesis route involves the benzylation of hydroxyl group of maltol (ethyl maltol using benzyl chloride conversion of the benazylated maltol (ethyl maltol to the N-acetonitril bezylated pyridinone derivatives by introducing the aminoacetonitril in pyridine solvent and cleavage of benzyl group by hydrogenation method or using the bromodimethyl borane to form the N-acetonitril or N- ethylamine- 3- hydroxypyridinones respectively.
    Results. In this work three final compounds such as 1- (2- aminoethyl- 2- methyl- 3-hydroxypyridin- 4- one, 1- (2- aminoethyl- 2- ethyl- 3- hydroxypyridin-4- one and 1- cyanomethyl -2- methyl- 3- hydroxypyridin- 4- one were synthesized.
    Discussion. Identification and structural elucidation of compounds were achieved by IH NMR and Mass spectra, elemental analysis and through physical constants. The biological effects of compounds will be studied in the near future.

  17. Developments in Bioremediation of Soils and Sediments Polluted with Metals and Radionuclides: 2. Field Research on Bioremediation of Metals and Radionuclides

    OpenAIRE

    Hazen, Terry C.; Tabak, Henry H.

    2007-01-01

    Bioremediation of metals and radionuclides has had many field tests, demonstrations, and full-scale implementations in recent years. Field research in this area has occurred for many different metals and radionuclides using a wide array of strategies. These strategies can be generally characterized in six major categories: biotransformation, bioaccumulation/bisorption, biodegradation of chelators, volatilization, treatment trains, and natural attenuation. For all field applications there are ...

  18. Carbon based secondary compounds do not provide protection against heavy metal road pollutants in epiphytic macrolichens.

    Science.gov (United States)

    Gauslaa, Yngvar; Yemets, Olena A; Asplund, Johan; Solhaug, Knut Asbjørn

    2016-01-15

    Lichens are useful monitoring organisms for heavy metal pollution. They are high in carbon based secondary compounds (CBSCs) among which some may chelate heavy metals and thus increase metal accumulation. This study quantifies CBSCs in four epiphytic lichens transplanted for 6months on stands along transects from a highway in southern Norway to search for relationships between concentrations of heavy metals and CBSCs along a gradient in heavy metal pollutants. Viability parameters and concentrations of 21 elements including nutrients and heavy metals in these lichen samples were reported in a separate paper. Medullary CBSCs in fruticose lichens (Ramalina farinacea, Usnea dasypoga) were reduced in the most polluted sites, but not in foliose ones (Parmelia sulcata, Lobaria pulmonaria), whereas cortical CBSC did not change with distance from the road in any species. Strong positive correlations only occurred between the major medullary compound stictic acid present in L. pulmonaria and most heavy metals, consistent with a chelating role of stictic acid, but not of other studied CBSCs or in other species. However, heavy metal chelating did not protect L. pulmonaria against damage because this species experienced the strongest reduction in viability in the polluted sites. CBSCs with an accumulation potential for heavy metals should be quantified in lichen biomonitoring studies of heavy metals because they, like stictic acid, could overshadow pollutant inputs in some species rendering biomonitoring data less useful. In the two fruticose lichen species, CBSCs decreased with increasing heavy metal concentration, probably because heavy metal exposure impaired secondary metabolism. Thus, we found no support for a heavy metal protection role of any CBSCs in studied epiphytic lichens. No intraspecific relationships occurred between CBSCs versus N or C/N-ratio. Interspecifically, medullary CBSCs decreased and cortical CBSCs increased with increasing C/N-ratio. Copyright © 2015

  19. Chemistry of bifunctional photoprobes. 3 -- Correlation between the efficiency of CH insertion by photolabile chelating agents and lifetimes of singlet nitrenes by flash photolysis: First example of photochemical attachment of 99mTc-complex with human serum albumin

    International Nuclear Information System (INIS)

    Pandurangi, R.S.; Lusiak, P.; Kuntz, R.R.; Volkert, W.A.; Rogowski, J.; Platz, M.S.

    1998-01-01

    Systematic functionalization of perfluoroaryl azides with chelating agents capable of complexing transition metals produces a new class of bifunctional photolabile chelating agents (BFPCAs). The strategy is shield the azide functionality from the electronic and steric influence of the electron-rich metal Pd through ester and amide bridges raised CH insertion efficiency to unprecedented levels (>92%) in a model solvent (cyclohexane). In contrast, perfluoroaryl azides attached to chelating agents via hydrazones show no significant CH insertion in cyclohexane upon photolysis. Measurements of the lifetimes of the singlet nitrenes derived from these agents by flash photolysis techniques correlate well with the efficiency of CH insertion by demonstrating longer lifetimes (10--50 times) for singlet nitrenes derived from azidotetrafluorinated esters and amides compared with the related hydrazones, which failed to yield significant CH insertion. A representative BFPCA 12 is chelated to diagnostic radionuclide 99m Tc and covalently attached to human serum albumin via photochemical activation extending the favorable bimolecular insertion characteristics of BFPCA to tracer level concentrations in buffer conditions. Flash photolysis experiments correlate singlet nitrene lifetimes with the efficiency of intermolecular insertion reactions. This work provides new photo-cross-linking technology, useful in radiodiagnostics and radiotherapy in nuclear medicine

  20. Adsorption of Cu(II), Hg(II), and Ni(II) ions by modified natural wool chelating fibers

    International Nuclear Information System (INIS)

    Monier, M.; Ayad, D.M.; Sarhan, A.A.

    2010-01-01

    The graft copolymerization of ethyl acrylate (EA) onto natural wool fibers initiated by potassium persulphate and Mohr's salt redox initiator system in limited aqueous medium was carried out in heterogeneous media. Ester groups of the grafted copolymers were partially converted into hydrazide function groups followed by hydrazone formation through reaction with isatin. Also the application of the modified fibers for metal ion uptake was studied using Cu(II), Hg(II) and Ni(II). The modified chelating fibers were characterized using FTIR spectroscopy, SEM and X-ray diffraction.

  1. Interaction of chelating agents with cadmium in mice and rats.

    Science.gov (United States)

    Eybl, V; Sýkora, J; Koutenský, J; Caisová, D; Schwartz, A; Mertl, F

    1984-01-01

    The influence of several chelating agents (CaDTPA, ZnDTPA, CaEDTA, ZnEDTA, DMSA, D-penicillamine and DMPS, DMP and DDC) on the acute toxicity of CdCl2 and on the whole body retention and tissue distribution of cadmium after the IV application of 115mCdCl2 was compared in mice. The chelating agents were applied immediately after the application of cadmium. CaDTPA, ZnDTPA and DMSA appeared to be the most effective antidotes. However, DMSA increased the amount of cadmium retained in kidneys. The treatment of cadmium-poisoned mice with the combination of DMSA (IP) and ZnDTPA (SC) (all the compounds were injected in equimolar dose) decreased the toxicity of cadmium more than treatment with one chelating agents (given in a 2:1 dose). However, by studying the effect of these chelating agents and their combination of the retention and distribution of Cd in mice, it was demonstrated that the combined application of the antidotes showed little or no improvement over the results obtained with the most effective of the individual components. In the urine of rats injected with CdCl2 and treated with the chelating agents (CaDTPA, ZnDTPA, DMSA), the presence of cadmium complexes was demonstrated. The formation of mixed ligand chelates in vivo was not proved. Experiments in mice given a single injection of 115mCd-labeled Cd complexes of DMPS, DMSA and DTPA showed a high retention of cadmium in the organisms after the IV application of CdDMPS and CdDMSA complexes. PMID:6734561

  2. Removal of heavy metal ions from wastewaters using dendrimer-functionalized multi-walled carbon nanotubes.

    Science.gov (United States)

    Iannazzo, Daniela; Pistone, Alessandro; Ziccarelli, Ida; Espro, Claudia; Galvagno, Signorino; Giofré, Salvatore V; Romeo, Roberto; Cicero, Nicola; Bua, Giuseppe D; Lanza, Giuseppe; Legnani, Laura; Chiacchio, Maria A

    2017-06-01

    Dendrimer-functionalized multi-walled carbon nanotubes (MWCNT) for heavy metal ion removal from wastewaters were developed. Triazole dendrimers (TD) were built directly onto the carbon nanotube surface by successive click chemistry reactions affording the zero- and first-generation dendrimer-functionalized MWCNT (MWCNT-TD1 and MWCNT-TD2). The Moedritzer-Irani reaction carried out on the amino groups present on the MWCNT-TD2 sample gave the corresponding α-aminophosphonate nanosystem MWCNT-TD2P. Both MWCNT-TD2 and MWCNT-TD2P nanosystems have been characterized by physical, chemical, and morphological analyses. Their chelating abilities towards the toxic metal ions Pb 2+ , Hg 2+ , and Ni 2+ and the harmless Ca 2+ ion have been experimentally evaluated in the two different sets of experiments and at the salt concentrations of 1 mg/mL or 1 μg/mL by inductively coupled plasma mass spectrometry (ICP-MS). The results of these studies pointed out the interesting chelating behavior for the phosphonated nanosystem towards the Hg 2+ ion. The complexation mode of the best chelating system MWCNT-TD2P with mercury was investigated through density functional theory (DFT) calculations, suggesting a chelation mechanism involving the two oxygen atoms of the phosphate group. The synthesized dendrimers, supported on the multi-walled carbon nanotubes, have shown the potential to be used for the selective toxic metal ion removal and recovery.

  3. Synergy and antagonism between iron chelators and antifungal drugs in Cryptococcus.

    Science.gov (United States)

    Lai, Yu-Wen; Campbell, Leona T; Wilkins, Marc R; Pang, Chi Nam Ignatius; Chen, Sharon; Carter, Dee A

    2016-10-01

    Fungal infections remain very difficult to treat, and developing new antifungal drugs is difficult and expensive. Recent approaches therefore seek to augment existing antifungals with synergistic agents that can lower the therapeutic dose, increase efficacy and prevent resistance from developing. Iron limitation can inhibit microbial growth, and iron chelators have been employed to treat fungal infections. In this study, chequerboard testing was used to explore combinations of iron chelators with antifungal agents against pathogenic Cryptococcus spp. with the aim of determining how disruption to iron homeostasis affects antifungal susceptibility. The iron chelators ethylenediaminetetraacetic acid (EDTA), deferoxamine (DFO), deferiprone (DFP), deferasirox (DSX), ciclopirox olamine and lactoferrin (LF) were paired with the antifungal agents amphotericin B (AmB), fluconazole, itraconazole, voriconazole and caspofungin. All chelators except for DFO increased the efficacy of AmB, and significant synergy was seen between AmB and LF for all Cryptococcus strains. Addition of exogenous iron rescued cells from the antifungal effect of LF alone but could not prevent inhibition by AmB + LF, indicating that synergy was not due primarily to iron chelation but to other properties of LF that were potentiated in the presence of AmB. Significant synergy was not seen consistently for other antifungal-chelator combinations, and EDTA, DSX and DFP antagonised the activity of azole drugs in strains of Cryptococcus neoformans var. grubii. This study highlights the range of interactions that can be induced by chelators and indicates that most antifungal drugs are not enhanced by iron limitation in Cryptococcus. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  4. Streptomyces sp. MUM212 as a Source of Antioxidants with Radical Scavenging and Metal Chelating Properties

    Directory of Open Access Journals (Sweden)

    Loh Teng-Hern Tan

    2017-05-01

    Full Text Available Reactive oxygen species and other radicals potentially cause oxidative damage to proteins, lipids, and DNA which may ultimately lead to various complications including mutations, carcinogenesis, neurodegeneration, cardiovascular disease, aging, and inflammatory disease. Recent reports demonstrate that Streptomyces bacteria produce metabolites with potent antioxidant activity that may be developed into therapeutic drugs to combat oxidative stress. This study shows that Streptomyces sp. MUM212 which was isolated from mangrove soil in Kuala Selangor, Malaysia, could be a potential source of antioxidants. Strain MUM212 was characterized and determined as belonging to the genus Streptomyces using 16S rRNA gene phylogenetic analysis. The MUM212 extract demonstrated significant antioxidant activity through DPPH, ABTS and superoxide radical scavenging assays and also metal-chelating activity of 22.03 ± 3.01%, 61.52 ± 3.13%, 37.47 ± 1.79%, and 41.98 ± 0.73% at 4 mg/mL, respectively. Moreover, MUM212 extract was demonstrated to inhibit lipid peroxidation up to 16.72 ± 2.64% at 4 mg/mL and restore survival of Vero cells from H2O2-induced oxidative damages. The antioxidant activities from the MUM212 extract correlated well with its total phenolic contents; and this in turn was in keeping with the gas chromatography–mass spectrometry analysis which revealed the presence of phenolic compounds that could be responsible for the antioxidant properties of the extract. Other chemical constituents detected included hydrocarbons, alcohols and cyclic dipeptides which may have contributed to the overall antioxidant capacity of MUM212 extract. As a whole, strain MUM212 seems to have potential as a promising source of novel molecules for future development of antioxidative therapeutic agents against oxidative stress-related diseases.

  5. Chelation and stabilization of berkelium in oxidation state +IV

    Science.gov (United States)

    Deblonde, Gauthier J.-P.; Sturzbecher-Hoehne, Manuel; Rupert, Peter B.; An, Dahlia D.; Illy, Marie-Claire; Ralston, Corie Y.; Brabec, Jiri; de Jong, Wibe A.; Strong, Roland K.; Abergel, Rebecca J.

    2017-09-01

    Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far remained elusive. Here we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin—a mammalian metal transporter—in contrast to the negatively charged species obtained with neighbouring trivalent actinides americium, curium and californium (Cf). The corresponding Cf(III)-ligand-protein ternary adduct was characterized by X-ray diffraction analysis. Combined with theoretical predictions, these data add significant insight to the field of transplutonium chemistry, and may lead to innovative Bk separation and purification processes.

  6. f-Element Ion Chelation in Highly Basic Media - Final Report

    International Nuclear Information System (INIS)

    Paine, R.T.

    2000-01-01

    A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelator s for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

  7. Click-to-Chelate: Development of Technetium and Rhenium-Tricarbonyl Labeled Radiopharmaceuticals

    Directory of Open Access Journals (Sweden)

    Thomas L. Mindt

    2013-03-01

    Full Text Available The Click-to-Chelate approach is a highly efficient strategy for the radiolabeling of molecules of medicinal interest with technetium and rhenium-tricarbonyl cores. Reaction of azide-functionalized molecules with alkyne prochelators by the Cu(I-catalyzed azide-alkyne cycloaddition (CuAAC; click reaction enables the simultaneous synthesis and conjugation of tridentate chelating systems for the stable complexation of the radiometals. In many cases, the functionalization of (biomolecules with the ligand system and radiolabeling can be achieved by convenient one-pot procedures. Since its first report in 2006, Click-to-Chelate has been applied to the development of numerous novel radiotracers with promising potential for translation into the clinic. This review summarizes the use of the Click-to-Chelate approach in radiopharmaceutical sciences and provides a perspective for future applications.

  8. Protracted chelate therapy after incorporation of plutonium 239 in rats

    International Nuclear Information System (INIS)

    Gemenetzis, E.

    1976-01-01

    The author has tested in how far 239 Pu can be mobilized by Ca and Zn, Desfenioxamin B(DFDA) and by combined doses of Ca-DTPA and DFDA. The pre-experiment covered the 239 Pu-metabolism in untreated male and female rats and the distribution in dependence of the way of application. If treatment is started immediately by multiple chelate doses, the first two injections play the main part in the decorporation of 239 Pu. The combination Ca-DTPA30 + DFDA30 μMol x kg -1 is proved to be the best means of decorporation for the whole body. The efficiency of another therapy depends essentially on the treatment used, a daily treatment showing the best effects. If treatment is started later with multiple chelate doses, the total decorporation efficiency is of less value, especially in the skeleton. Aequimolar doses of Ca-DTPA and Zn-DTPA have the same degree of efficiency. This indicates that during protracted chelate treatment starting later, Ca-DTPA could be substituted by the less toxic Zn-DTPA after incorporation of 239 Pu. These results show that intermittant administration of the week's dose is more efficient than a single chelate administration of the whole week's dose at once. Permanent chelate infusion does not seem necessary in any case since it has the same effect as 3 to 5 injections per week and is difficult to carry out in medical practice. Thus, it seems advisable to divide up the weekly dose into 3-5 injections. In case of a wound contamination, the efficiency of immediate intensive treatment depends on the 239 Pu compound used, on the chelate used, and on its dosage. (orig.) [de

  9. Development of a Novel Optical Biosensor for Detection of Organophoshorus Pesticides Based on Methyl Parathion Hydrolase Immobilized by Metal-Chelate Affinity

    Science.gov (United States)

    Lan, Wensheng; Chen, Guoping; Cui, Feng; Tan, Feng; Liu, Ran; Yushupujiang, Maolidan

    2012-01-01

    We have developed a novel optical biosensor device using recombinant methyl parathion hydrolase (MPH) enzyme immobilized on agarose by metal-chelate affinity to detect organophosphorus (OP) compounds with a nitrophenyl group. The biosensor principle is based on the optical measurement of the product of OP catalysis by MPH (p-nitrophenol). Briefly, MPH containing six sequential histidines (6× His tag) at its N-terminal was bound to nitrilotriacetic acid (NTA) agarose with Ni ions, resulting in the flexible immobilization of the bio-reaction platform. The optical biosensing system consisted of two light-emitting diodes (LEDs) and one photodiode. The LED that emitted light at the wavelength of the maximum absorption for p-nitrophenol served as the signal light, while the other LED that showed no absorbance served as the reference light. The optical sensing system detected absorbance that was linearly correlated to methyl parathion (MP) concentration and the detection limit was estimated to be 4 μM. Sensor hysteresis was investigated and the results showed that at lower concentration range of MP the difference got from the opposite process curves was very small. With its easy immobilization of enzymes and simple design in structure, the system has the potential for development into a practical portable detector for field applications. PMID:23012501

  10. Field-Portable Immunoassay Instruments and Reagents to Measure Chelators and Mobile Forms of Uranium

    International Nuclear Information System (INIS)

    Blake, Diane A.

    2003-01-01

    The goals for the 3-year project period are (1) to test and validate the present uranium sensor and develop protocols for its use at the NABIR Field Research Center; (2) to develop new reagents that will provide superior performance for the present hand-held immunosensor; and (3) to develop new antibodies that will permit this sensor to also measure other environmental contaminants (chromium, mercury, and/or DTPA). Sensor design modifications are underway via international collaborations. New reagents that will provide superior performance for the present hand-held immunosensor are being prepared and tested. New methods have been developed, to produce recombinant forms of metal-specific monoclonal antibodies for use with the sensor. Site-directed mutagenesis experiments are underway to determine the mechanisms of binding. Immunization experiments with sheep and rabbits to develop new recombinant forms of antibodies to metal-chelate complexes (chromium, mercury, and/or DTPA) have been initiated

  11. Adsorption of Cu(II), Hg(II), and Ni(II) ions by modified natural wool chelating fibers

    Energy Technology Data Exchange (ETDEWEB)

    Monier, M., E-mail: monierchem@yahoo.com [Chemistry Department, Drexel University, Philadelphia, PA (United States); Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Ayad, D.M.; Sarhan, A.A. [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt)

    2010-04-15

    The graft copolymerization of ethyl acrylate (EA) onto natural wool fibers initiated by potassium persulphate and Mohr's salt redox initiator system in limited aqueous medium was carried out in heterogeneous media. Ester groups of the grafted copolymers were partially converted into hydrazide function groups followed by hydrazone formation through reaction with isatin. Also the application of the modified fibers for metal ion uptake was studied using Cu(II), Hg(II) and Ni(II). The modified chelating fibers were characterized using FTIR spectroscopy, SEM and X-ray diffraction.

  12. Adsorption of Cu(II), Hg(II), and Ni(II) ions by modified natural wool chelating fibers.

    Science.gov (United States)

    Monier, M; Ayad, D M; Sarhan, A A

    2010-04-15

    The graft copolymerization of ethyl acrylate (EA) onto natural wool fibers initiated by potassium persulphate and Mohr's salt redox initiator system in limited aqueous medium was carried out in heterogeneous media. Ester groups of the grafted copolymers were partially converted into hydrazide function groups followed by hydrazone formation through reaction with isatin. Also the application of the modified fibers for metal ion uptake was studied using Cu(II), Hg(II) and Ni(II). The modified chelating fibers were characterized using FTIR spectroscopy, SEM and X-ray diffraction. 2009 Elsevier B.V. All rights reserved.

  13. Development of a treatment process for the removal of heavy metals from raw water for drinking water supply using chelating ion exchange resins. Subproject 1. Final report; Entwicklung der Verfahrenstechnik zur Eliminierung von Schwermetallen aus Rohwaessern zur Trinkwassergewinnung mit chelatbildenden Kationenaustauscherharzen zur technischen Reife. Teilprojekt 1. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Overath, H.; Stetter, D.; Doerdelmann, O.

    2002-07-01

    Chelating cation exchange resins with iminodiacetic acid group (Lewatit TP 207 and Amberlite IRC 748) were tested for the removal of heavy metals in a drinking water treatment plant. The pilot scale filtration experiments were conducted by varying the operating conditions, such as flow rate and feed concentrations. Heavy metal concentrations (nickel, lead, cadmium, zinc) in the feed were adjusted between 20 and 200 {mu}g/L. Different methods for regeneration and conditioning of the resins were developed and investigated. Finally the ion exchange resins were tested according to German health regulations for ion exchangers in drinking water treatment. (orig.)

  14. Characterization of commercial iron chelates and their behavior in an alkaline and calcareous soil.

    Science.gov (United States)

    Cantera, Rodrigo G; Zamarreño, Angel M; García-Mina, José M

    2002-12-18

    Iron deficiency is a common problem for many plants grown in alkaline and calcareous soils. To correct this problem, iron is supplied to plants as chelates. Several iron chelates are sold under diverse trademarks with different characteristics. This work evaluated 18 commercial products containing the most representative chelated iron sources used in agricultural practice in Spain when the study was done, namely the ferric chelates of EDDHA, EDDHMA, EDDCHA, EDDHSA, EDTA, and DTPA. The chelates were comprehensively characterized and quantitated by several techniques, including several chromatographic methods. Iron and chelate dynamics in soil were also studied in a model alkaline and calcareous soil. Results indicate that, in this model soil, among the different iron compounds studied only FeEDDHA and analogues have the capacity to maintain soluble iron in soil solution over time. These results are in agreement with general experience under field conditions. Furthermore, among the different ortho-ortho isomers of FeEDDHA's, FeEDDHSA and FeEDDCHA showed greater capacity than FeEDDHA and FeEDDHMA to maintain the chelated iron in soil solution over time.

  15. Mixed metal complexes of isoniazid and ascorbic acid: chelation ...

    African Journals Online (AJOL)

    Novel mixed complexes of isoniazid and ascorbic acid have been synthesized and characterized using infrared, electronic absorption data, elemental analysis, molar conductivity, melting point, thin layer chromatography and solubility. The metal ions involved in the complex formation are Cu2+, Zn2+ and Cd2+. The melting ...

  16. Chelate chase of radiopharmaceuticals reversibly bound to monoclonal antibodies improves dosimetry

    International Nuclear Information System (INIS)

    Goodwin, D.A.; Smith, S.I.; Meares, C.F.; David, G.S.; McTigue, M.; Finston, R.A.

    1986-01-01

    One hundred micrograms of monoclonal antibody (MoAb) CHA 255 with a binding constant Kb of 4 x 10 9 was complexed with indium-111 labeled BLEDTA II, GLEDTA IV, benzyl EDTA, and an EDTA conjugate of Fab. The 24-hour tumor and organ distribution in BALB/c mice bearing KHJJ tumors was studied for each compound alone, the antibody complex, and 3 hours following a chelate chase of the antibody complex. Whole-body biological half-life was measured for 7 days with and without a chelate chase for each antibody complex. The 24-hour whole-body counts dropped 20-60% within 3 hours of administering the chelate chase. Blood concentration fell over 89% within 3 hours of administering the chase and there was a decrease in concentration in all organs, except the kidneys, of 10 to 85%. Theoretical equivalent human doses were calculated from the 24-hour organ concentrations, effective half-life, and MIRD 11 S values (absorbed dose per cumulated activity). Liver and spleen were the target organs, with the dose ranging from 0.50 to 3.91 rads per millicurie. The reduction in organ radiation dose varied up to 95% following the chelate chase. Rapid selective renal clearance of chelate labeled radiopharmaceuticals by competitive inhibition (chelate chase) of their reversible binding to monoclonal antibodies, greatly improves the radiation dosimetry of tumor imaging agents. 28 references, 5 figures, 5 tables

  17. Surface Engineering of PAMAM-SDB Chelating Resin with Diglycolamic Acid (DGA) Functional Group for Efficient Sorption of U(VI) and Th(IV) from Aqueous Medium

    Energy Technology Data Exchange (ETDEWEB)

    Ilaiyaraja, P.; Venkatraman, B., E-mail: chemila07@gmail.com [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Deb, A.K. Singha [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India); Ponraju, D. [Safety Engineering Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Ali, Sk. Musharaf [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India)

    2017-04-15

    Highlights: • A new DGA-PAMAM-SDB chelating resin has been synthesized for actinide sorption. • Maximum sorption capacities of resin are 682 and 544.2 mg g{sup −1}for U(VI) and Th(IV). • DGA-PAMAM-SDB chelating resin could be regenerated and reused. • DFT calculation of actinides interaction with resin corroborates the experimental. • Resin is effective for sorption of actinides from both aqueous and HNO{sub 3} medium. - Abstract: A novel chelating resin obtained via growth of PAMAM dendron on surface of styrene divinyl benzene resin beads, followed by diglycolamic acid functionalization of the dendrimer terminal. Batch experiments were conducted to study the effects of pH, nitric acid concentration, amount of adsorbent, shaking time, initial metal ion concentration and temperature on U(VI) and Th(IV) adsorption efficiency. Diglycolamic acid terminated PAMAM dendrimer functionalized styrene divinylbenzene chelating resin (DGA-PAMAM-SDB) is found to be an efficient candidate for the removal of U(VI) and Th(IV) ions from aqueous (pH > 4) and nitric acid media (> 3 M). The sorption equilibrium could be reached within 60 min, and the experimental data fits with pseudo-second-order model. Langmuir sorption isotherm model correlates well with sorption equilibrium data. The maximum U(VI) and Th(IV) sorption capacity onto DGA-PAMAMG{sub 5}-SDB was estimated to be about 682 and 544.2 mg g{sup −1} respectively at 25 °C. The interaction of actinides and chelating resin is reversible and hence, the resin can be regenerated and reused. DFT calculation on the interaction of U(VI) and Th(IV) ions with chelating resin validates the experimental findings.

  18. IRON CHELATION THERAPY IN THALASSEMIA SYNDROMES

    Directory of Open Access Journals (Sweden)

    Paolo Cianciulli

    2009-06-01

    Full Text Available Transfusional hemosiderosis is a frequent complication in patients with transfusion dependent chronic diseases such as  thalassemias and severe type of sickle cell diseases. As there are no physiological mechanisms to excrete the iron contained in transfused red cells (1 unit of blood contains approximately 200 mg of iron the excess of iron is stored in various organs. Cardiomyopathy is the most severe complication covering more than 70% of the causes of death of thalassemic patients. Although the current reference standard iron chelator deferoxamine (DFO has been used clinically for over four decades, its effectiveness is limited by a demanding therapeutic regimen that leads to poor compliance. Despite poor compliance, because of the inconvenience of subcutaneous infusion, DFO improved considerably the survival and quality of life of patients with thalassemia. Deferiprone since 1998 and Deferasirox since 2005 were licensed for clinical use. The oral chelators have a better compliance because of oral use, a comparable efficacy to DFO in iron excretion and probably a better penetration to myocardial cells. Considerable increase in iron excretion was documented with combination therapy of DFO and Deferiprone. The proper use of the three chelators will improve the prevention and treatment of iron overload, it will reduce  complications, and improve survival and quality of life of transfused patients

  19. Chelation therapy to treat atherosclerosis, particularly in diabetes: is it time to reconsider?

    Science.gov (United States)

    Lamas, Gervasio A; Ergui, Ian

    2016-08-01

    Case reports and case series have suggested a possible beneficial effect of chelation therapy in patients with atherosclerotic disease. Small randomized trials conducted in patients with angina or peripheral artery disease, however, were not sufficiently powered to provide conclusive evidence on clinical outcomes. The Trial to Assess Chelation Therapy (TACT) was the first randomized trial adequately powered to detect the effects of chelation therapy on clinical endpoints. We discuss results and future research. Expert commentary: Chelation reduced adverse cardiovascular events in a post myocardial infarction (MI) population. Patients with diabetes demonstrated even greater benefit, with a number needed to treat of 6.5 patients to prevent a cardiac event over 5 years, with a 41% relative reduction in risk of a cardiac event (p = 0.0002). These results led to the revision of the ACC/AHA guideline recommendations for chelation therapy, changing its classification from class III to class IIb. TACT2, a replicative trial, will assess the effects of chelation therapy on cardiovascular outcomes in diabetic patients with a prior myocardial infarction. We are seeking participating sites for TACT2.

  20. Phytoextraction of 55-year-old wastewater-irrigated soil in a Zn-Pb mine district: effect of plant species and chelators.

    Science.gov (United States)

    Tai, YiPing; Yang, YuFen; Li, ZhiAn; Yang, Yang; Wang, JiaXi; Zhuang, Ping; Zou, Bi

    2017-07-16

    Untreated water from mining sites spreads heavy metal contamination. The present study assessed the phytoextraction performance of heavy metal-accumulating plants and the effects of chemical chelators on cadmium (Cd), lead (Pb), zinc (Zn), and copper (Cu) removal from paddy fields that have been continuously irrigated with mining wastewater from mines for 55 years. Outdoor pot experiments showed that the total Pb, Zn, and Cd content was lower in the rhizosphere soil of Amaranthus hypochondriacus than in that of Sedum alfredii, Solanum nigrum, and Sorghum bicolor. The aboveground biomass (dry weight) and relative growth rate of A. hypochondriacus were significantly higher than that of the other three species (P phytoextraction effect.

  1. Geochemically structural characteristics of municipal solid waste incineration fly ash particles and mineralogical surface conversions by chelate treatment.

    Science.gov (United States)

    Kitamura, Hiroki; Sawada, Takaya; Shimaoka, Takayuki; Takahashi, Fumitake

    2016-01-01

    Leaching behaviors of heavy metals contained in municipal solid waste incineration (MSWI) fly ash have been studied well. However, micro-characteristics of MSWI fly ash particles are still uncertain and might be non-negligible to describe their leaching behaviors. Therefore, this study investigated micro-characteristics of MSWI fly ash particles, especially their structural properties and impacts of chelate treatment on surface characteristics. According to SEM observations, raw fly ash particles could be categorized into four types based on their shapes. Because chelate treatment changed the surface of fly ash particles dramatically owing to secondary mineral formations like ettringite, two more types could be categorized for chelate-treated fly ash particles. Acid extraction experiments suggest that fly ash particles, tested in this study, consist of Si-base insoluble core structure, Al/Ca/Si-base semi-soluble matrices inside the body, and KCl/NaCl-base soluble aggregates on the surface. Scanning electron microscope (SEM) observations of the same fly ash particles during twice moistening treatments showed that KCl/NaCl moved under wet condition and concentrated at different places on the particle surface. However, element mobility depended on secondary mineral formations. When insoluble mineral like gypsum was generated and covered the particle surface, it inhibited element transfer under wet condition. Surface characteristics including secondary mineral formation of MSWI fly ash particles are likely non-negligible to describe trace element leaching behaviors.

  2. Studies of the competition for thorium ion between chelating agents and bovine serum albumin

    International Nuclear Information System (INIS)

    Luo Meichu; Zhang Meizhen; Sun Meizhen; Chen Shijie

    1995-01-01

    Fourteen chelation agents (polyaminopolcarboxylate type--TTHA, DTPA, EDTA; phenolicpolycarboxylate type--811, 8102, 7601, 7602, 7603, 7616, 7711, 7724, 7803, 7804, 8307) were studied their competitive ability to mobilize the thorium with bovine serum albumin (BSA). The experimental results showed that the competitive ability of TTHA, 8102, 811 to chelate Thorium with BSA were the strongest, and EDTA was the worst in all chelating agents. The measured order of the competitive ability of chelators is basically consistent with animal experimental results in vivo. The parameter F is defined as the competitive ability of chelators. F is taken as a screening criterion for de-corporate thorium which is simple, quick and effective method in vitro

  3. Evaluation of macrocyclic hydroxyisophthalamide ligands as chelators for zirconium-89.

    Science.gov (United States)

    Bhatt, Nikunj B; Pandya, Darpan N; Xu, Jide; Tatum, David; Magda, Darren; Wadas, Thaddeus J

    2017-01-01

    The development of bifunctional chelators (BFCs) for zirconium-89 immuno-PET applications is an area of active research. Herein we report the synthesis and evaluation of octadentate hydroxyisophthalamide ligands (1 and 2) as zirconium-89 chelators. While both radiometal complexes could be prepared quantitatively and with excellent specific activity, preparation of 89Zr-1 required elevated temperature and an increased reaction time. 89Zr-1 was more stable than 89Zr-2 when challenged in vitro by excess DTPA or serum proteins and in vivo during acute biodistribution studies. Differences in radiometal complex stability arise from structural changes between the two ligand systems, and suggest further ligand optimization is necessary to enhance 89Zr chelation.

  4. Evaluation of macrocyclic hydroxyisophthalamide ligands as chelators for zirconium-89.

    Directory of Open Access Journals (Sweden)

    Nikunj B Bhatt

    Full Text Available The development of bifunctional chelators (BFCs for zirconium-89 immuno-PET applications is an area of active research. Herein we report the synthesis and evaluation of octadentate hydroxyisophthalamide ligands (1 and 2 as zirconium-89 chelators. While both radiometal complexes could be prepared quantitatively and with excellent specific activity, preparation of 89Zr-1 required elevated temperature and an increased reaction time. 89Zr-1 was more stable than 89Zr-2 when challenged in vitro by excess DTPA or serum proteins and in vivo during acute biodistribution studies. Differences in radiometal complex stability arise from structural changes between the two ligand systems, and suggest further ligand optimization is necessary to enhance 89Zr chelation.

  5. Group 4 Metal Complexes of Chelating Cyclopentadienyl-ketimide Ligands

    Czech Academy of Sciences Publication Activity Database

    Večeřa, M.; Varga, Vojtěch; Císařová, I.; Pinkas, Jiří; Kucharczyk, P.; Sedlařík, V.; Lamač, Martin

    2016-01-01

    Roč. 35, č. 5 (2016), s. 785-798 ISSN 0276-7333 R&D Projects: GA ČR(CZ) GA14-08531S; GA MŠk(CZ) LO1504 Institutional support: RVO:61388955 Keywords : group 4 metal complexes * cyclopentadienyl-ketimide ligands * metallocenes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.862, year: 2016

  6. Biological activity of Fe(III) aquo-complexes towards ferric chelate reductase (FCR).

    Science.gov (United States)

    Escudero, Rosa; Gómez-Gallego, Mar; Romano, Santiago; Fernández, Israel; Gutiérrez-Alonso, Ángel; Sierra, Miguel A; López-Rayo, Sandra; Nadal, Paloma; Lucena, Juan J

    2012-03-21

    In this study we have obtained experimental evidence that confirms the high activity of aquo complexes III and IV towards the enzyme FCR, responsible for the reduction of Fe(III) to Fe(II) in the process of iron acquisition by plants. The in vivo FCR assays in roots of stressed cucumber plants have shown a higher efficiency of the family of complexes III and a striking structure-activity relationship with the nature of the substituent placed in a phenyl group far away from the metal center. The results obtained in this work demonstrate that all the aquo compounds tested interact efficiently with the enzyme FCR and hence constitute a new concept of iron chelates that could be of great use in agronomy.

  7. Synthesis of new water-soluble metal-binding polymers: Combinatorial chemistry approach. 1997 mid-year progress report

    International Nuclear Information System (INIS)

    Smith, B.F.

    1997-01-01

    'The first objective of this research is to develop rapid discovery and optimization approaches to new water-soluble chelating polymers. A byproduct of the development approach will be the new, selective, and efficient metal-binding agents. The second objective is to evaluate the concept of using water and organic soluble polymers as new solid supports for combinatorial synthesis. The technology under development, Polymer Filtration (PF), is a technique to selectively remove or recover hazardous and valuable metal ions and radionuclides from various dilute aqueous streams. Not only can this technology be used to remediate contaminated soils and solid surfaces and treat aqueous wastes, it can also be incorporated into facilities as a pollution prevention and waste minimization technology. Polymer Filtration uses water-soluble metal-binding polymers to sequester metal ions in dilute solution. The water-soluble polymers have a sufficiently large molecular size that they can be separated and concentrated using commercial ultrafiltration technology. Water, small organic molecules, and unbound metals pass freely through the ultrafiltration membrane while concentrating the metal-binding polymer. The polymers can then be reused by changing the solution conditions to release the metal ions. The metal-ions are recovered in concentrated form for recycle or disposal using a diafiltration process. The water-soluble polymer can be recycled for further aqueous-stream processing. To advance Polymer Filtration technology to the selectivity levels required for DOE needs. fixture directions in Polymer Filtration must include rapid development, testing, and characterization of new metal-binding polymers. The development of new chelating molecules can be equated to the process of new drugs or new materials discovery. Thus, the authors want to build upon and adapt the combinatorial chemistry approaches developed for rapid molecule generation for the drug industry to the rapid

  8. Gold nanoparticles modified with coordination compounds of metals: synthesis and application

    International Nuclear Information System (INIS)

    Beloglazkina, Elena K; Majouga, Alexander G; Romashkina, Renata B; Zyk, Nikolai V; Zefirov, Nikolai S

    2012-01-01

    The data on the preparation methods and applications of gold nanoparticles with coordinated metal ions on the surfaces are generalized. The currently available data on the interaction of metal ions with gold nanoparticles modified with organic (particularly, sulfur-containing) ligands comprising terminal chelating groups are considered in detail as well as the applications of such modified nanoparticles. The bibliography includes 141 references.

  9. Transition metal coordination chemistry ofN,N-bis(2-{pyrid-2-ylethyl})hydroxylamine.

    Science.gov (United States)

    Belock, Christopher W; Cetin, Anil; Barone, Natalie V; Ziegler, Christopher J

    2008-08-18

    Although directly relevant to metal mediated biological nitrification as well as the coordination chemistry of peroxide, the metal complexes of hydroxylamines and their functionalized variants remain largely unexplored. The chelating hydroxylamine ligand N,N-bis(2-{pyrid-2-ylethyl})hydroxylamine can be readily generated via a solvent free reaction in high purity; however, the ligand is prone to decomposition which can hamper metal reaction. N,N-bis(2-{pyrid-2-ylethyl})hydroxylamine forms stable complexes with chromium(III), manganese(II), nickel(II), and cadmium(II) ions, coordinating in a side-on mode in the case of chromium and via the nitrogen in the case of the latter three metal ions. The hydroxylamine ligand can also be reduced to form N,N-bis(2-{pyrid-2-ylethyl})amine upon exposure to a stoichiometric amount of the metal salts cobalt(II) nitrate, vanadium(III) chloride, and iron(II) chloride. In the reaction with cobalt nitrate, the reduced ligand then chelates to the metal to form [N,N-bis(2-{pyrid-2-ylethyl})amine]dinitrocobalt(II). Upon reaction with vanadium(III) chloride and iron(III) chloride, the reduced ligand is isolated as the protonated free base, resulting from a metal-mediated decomposition reaction.

  10. Behavior of phenolic substances in the decaying process of plants. V. Elution of heavy metals with phenolic acids from soil

    Energy Technology Data Exchange (ETDEWEB)

    Shindo, H; Kuwatsuka, S

    1977-01-01

    The relationship between the elution of heavy metals with phenolic substances and the chemical structure of phenolic substances, as well as the interaction between phenolic substances and metals were studied using batch and column methods. The elution of 3 metals (Fe, Al and Mn) with 4 phenolic acids (rho-hydroxybenzoic, salicylic, ..cap alpha..-resorcylic, and protocatechuic acids) and phthalic acid were investigated using 3 different soils. The results are as follows: (1) The elution of heavy metals was largely influenced by the chemical structures of the phenolic acids. Protocatechuic, salicylic, and phthalic acids which had different chelating sites easily extracted iron, aluminum, and manganese from the soils. Hydroxybenzoic and ..cap alpha..-resorcylic acids which had no chelating sites contributed little to the elution process. (2) In many cases protocatechuic acid showed a stronger affinity to iron than to aluminum, but salicylic acid showed the opposite trend. The affinity of phthalic acid to metals was much less than that of both phenolic acids. (3) The elution of heavy metals was also influenced by the soil pH. The amounts of heavy metals eluted with protocatechuic acid increased as the soil pH increased. The amounts eluted with salicylic and phthalic acids increased as the soil pH decreased. (4) The results suggested that chelating phenolics such as protocatechuic and salicylic acids, which were exuded from plant residues or produced during the decaying process of plant residues, eluted heavy metals such as iron, aluminum and manganese from soil particles and accelerated the downward movement of these metal ions.

  11. Study of Anti-Fatigue Effect in Rats of Ferrous Chelates Including Hairtail Protein Hydrolysates

    Directory of Open Access Journals (Sweden)

    Saibo Huang

    2015-12-01

    Full Text Available The ability of ferrous chelates including hairtail protein hydrolysates to prevent and reduce fatigue was studied in rats. After hydrolysis of hairtail surimi with papain, the hairtail protein hydrolysates (HPH were separated into three groups by range of relative molecular weight using ultrafiltration membrane separation. Hairtail proteins were then chelated with ferrous ions, and the antioxidant activity, the amino acid composition and chelation rate of the three kinds of ferrous chelates including hairtail protein hydrolysates (Fe-HPH were determined. Among the three groups, the Fe-HPH chelate showing the best conditions was selected for the anti-fatigue animal experiment. For it, experimental rats were randomly divided into seven groups. Group A was designated as the negative control group given distilled water. Group B, the positive control group, was given glutathione. Groups C, D and E were designated as the Fe-HPH chelate treatment groups and given low, medium, and high doses, respectively. Group F was designated as HPH hydrolysate treatment group, and Group G was designated as FeCl2 treatment group. The different diets were orally administered to rats for 20 days. After that time, rats were subjected to forced swimming training after 1 h of gavage. Rats given Fe-FPH chelate had higher haemoglobin regeneration efficiency (HRE, longer exhaustive swimming time and higher SOD activity. Additionally, Fe-FPH chelate was found to significantly decrease the malondialdehyde content, visibly enhance the GSH-Px activity in liver and reduce blood lactic acid of rats. Fe-HPH chelate revealed an anti-fatigue effect, similar to or better than the positive control substance and superior to HPH or Fe when provided alone.

  12. Synthesis of new water-soluble metal-binding polymers: Combinatorial chemistry approach. 1998 annual progress report

    International Nuclear Information System (INIS)

    Kurth, M.J.; Miller, R.B.; Sawan, S.; Smith, B.F.

    1998-01-01

    '(1) Develop rapid discovery and optimization approaches to new water-soluble chelating polymers for use in Polymer Filtration (PF) systems, and (2) evaluate the concept of using water and organic soluble polymers as new solid supports for combinatorial synthesis. Polymer Filtration (PF), which uses water-soluble metal-binding polymers to sequester metal ions in dilute solution with ultrafiltration (UF) to separate the polymers, is a new technology to selectively remove or recover hazardous and valuable metal ions. Future directions in PF must include rapid development, testing, and characterization of new metal-binding polymers. Thus, the authors are building upon and adapting the combinatorial chemistry approach developed for rapid molecule generation for the drug industry to the rapid development of new chelating polymers. The authors have focused on four areas including the development of: (1) synthetic procedures, (2) small ultrafiltration equipment compatible with organic- and aqueous-based combinatorial synthesis, (3) rapid assay techniques, and (4) polymer characterization techniques.'

  13. Novel synergism by complex ligands in solvent extraction of rare earth metals(III) with β-diketones

    International Nuclear Information System (INIS)

    Imura, H.; Ebisawa, M.; Kato, M.; Ohashi, K.

    2006-01-01

    The extraction of rare earth metals(III) (RE) with hexafluoroacetylacetone (Hhfa) and 2-thenoyltrifluoroacetone (Htta) was studied in the presence of some cobalt(III) chelates such as tris(acetylacetonato)cobalt(III), tris(4-isopropyltropolonato)cobalt(III), tris(8-quinolinolato)cobalt(III), tris(8-quinolinethiolato)cobalt(III), and tris(diethyldithiocarbamato)cobalt(III) in benzene or toluene. The synergistic enhancement of the extraction of RE, especially of lanthanum(III) was found in all the systems. Therefore, those cobalt(III) chelates act as synergists or complex ligands. The equilibrium analysis and IR spectroscopic study were performed to evaluate the present synergistic mechanism. It was found that the RE-β-diketone chelates form 1:1 adducts, i.e., binuclear complexes, with the cobalt(III) chelates in the organic phase. The formation constants (β s,1 ) were determined and compared with those reported previously. The spectroscopic studies demonstrated that adducts have two different structures with inner- and outer-sphere coordination. In the former the cobalt(III) chelate directly coordinated to the RE ion and displaced the coordinated water molecules. In the latter the hydrogen-bonding was formed between the coordinating oxygen or sulfur atoms of cobalt(III) chelate and hydrogen atoms of the coordinated water molecules in the RE-β-diketone chelate. The types of the adducts are mainly due to the steric factors of the RE-β-diketone chelates and the cobalt(III) chelates

  14. Synthesis of a novel bicyclic bifunctional chelating agent

    International Nuclear Information System (INIS)

    Sweet, M.P.; Mease, R.C.; Joshi, V.; Srivastava, S.C.

    1994-01-01

    Semi-rigid ligands such as cyclohexyl EDTA (CDTA) and 4-isothiocyanato-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (4-ICE) form chelates that are more stable in vivo compared to those of EDTA or DTPA. The authors have synthesized a new class of ligands in which the metal-binding polyaminocarboxylate groups are incorporated onto the rigid bicyclo[2.2.2]octane ring system. These ligands are expected to contribute to even higher in vivo stability of radiometal complexes. The synthesis of the first in this series of ligands (2.3-diaminobicyclo[2.2.2]octane-N,N,N',N'-tetraacetic acid, BODTA) began with a Diels-Alder reaction of 1,3-diacetylimidazolin-2-one and 1,3-cyclohexadiene. Base hydrolysis afforded the diamine. Following alkylation of the diamine with ethyl iodoacetate and hydrogenation of the double bond, hydrolysis of the esters gave BODTA. For initial conjugation with proteins, an average of one carboxylic acid of BODTA was converted into an NHS ester. In vivo testing of radioimmunoconjugates, prepared using this method, is in progress

  15. Characterization of radionuclide-chelating agent complexes found in low-level radioactive decontamination waste. Literature review

    International Nuclear Information System (INIS)

    Serne, R.J.; Felmy, A.R.; Cantrell, K.J.; Krupka, K.M.; Campbell, J.A.; Bolton, H. Jr.; Fredrickson, J.K.

    1996-03-01

    The US Nuclear Regulatory Commission is responsible for regulating the safe land disposal of low-level radioactive wastes that may contain organic chelating agents. Such agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), picolinic acid, oxalic acid, and citric acid, and can form radionuclide-chelate complexes that may enhance the migration of radionuclides from disposal sites. Data from the available literature indicate that chelates can leach from solidified decontamination wastes in moderate concentration (1--100 ppm) and can potentially complex certain radionuclides in the leachates. In general it appears that both EDTA and DTPA have the potential to mobilize radionuclides from waste disposal sites because such chelates can leach in moderate concentration, form strong radionuclide-chelate complexes, and can be recalcitrant to biodegradation. It also appears that oxalic acid and citric acid will not greatly enhance the mobility of radionuclides from waste disposal sites because these chelates do not appear to leach in high concentration, tend to form relatively weak radionuclide-chelate complexes, and can be readily biodegraded. In the case of picolinic acid, insufficient data are available on adsorption, complexation of key radionuclides (such as the actinides), and biodegradation to make definitive predictions, although the available data indicate that picolinic acid can chelate certain radionuclides in the leachates

  16. Characterization of radionuclide-chelating agent complexes found in low-level radioactive decontamination waste. Literature review

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R.J.; Felmy, A.R.; Cantrell, K.J.; Krupka, K.M.; Campbell, J.A.; Bolton, H. Jr.; Fredrickson, J.K. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-03-01

    The US Nuclear Regulatory Commission is responsible for regulating the safe land disposal of low-level radioactive wastes that may contain organic chelating agents. Such agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), picolinic acid, oxalic acid, and citric acid, and can form radionuclide-chelate complexes that may enhance the migration of radionuclides from disposal sites. Data from the available literature indicate that chelates can leach from solidified decontamination wastes in moderate concentration (1--100 ppm) and can potentially complex certain radionuclides in the leachates. In general it appears that both EDTA and DTPA have the potential to mobilize radionuclides from waste disposal sites because such chelates can leach in moderate concentration, form strong radionuclide-chelate complexes, and can be recalcitrant to biodegradation. It also appears that oxalic acid and citric acid will not greatly enhance the mobility of radionuclides from waste disposal sites because these chelates do not appear to leach in high concentration, tend to form relatively weak radionuclide-chelate complexes, and can be readily biodegraded. In the case of picolinic acid, insufficient data are available on adsorption, complexation of key radionuclides (such as the actinides), and biodegradation to make definitive predictions, although the available data indicate that picolinic acid can chelate certain radionuclides in the leachates.

  17. Inositol hexa-phosphate: a potential chelating agent for uranium

    International Nuclear Information System (INIS)

    Cebrian, D.; Tapia, A.; Real, A.; Morcillo, M.A.

    2007-01-01

    Chelation therapy is an optimal method to reduce the radionuclide-related risks. In the case of uranium incorporation, the treatment of choice is so far i.v infusion of a 1.4% sodium bicarbonate solution, but the efficacy has been proved to be not very high. In this study, we examine the efficacy of some substances: bicarbonate, citrate, diethylenetriamine pentaacetic acid (DTPA), ethidronate (EHBP) and inositol hexa-phosphate (phytic acid) to chelate uranium using a test developed by Braun et al. Different concentrations of phytic acid, an abundant component of plant seeds that is widely distributed in animal cells and tissues in substantial levels, were tested and compared to the same concentrations of sodium citrate, bicarbonate, EHBP and DTPA. The results showed a strong affinity of inositol hexa-phosphate for uranium, suggesting that it could be an effective chelating agent for uranium in vivo. (authors)

  18. Design, synthesis and evaluation of carbamoyl-methyl-phosphine sulfide (CMPS)-based chelates for separation of lanthanides and actinides

    Energy Technology Data Exchange (ETDEWEB)

    Matlokaa, K.; Saha, A.K.; Srinivasan, P.; Scott, M.J. [Florida Univ., Dept. of Chemistry, FL (United States)

    2007-10-15

    C{sub 3}-symmetric tri-phenoxy-methane platforms were substituted with carbamoyl-methyl-phosphine sulfide arms and these tris-CMPS compounds were evaluated as extractants for f-element metal ions from 1 M nitric acid solution. Their properties were compared to the carbamoyl-methyl-phosphine oxide derivatives on the same tri-phenoxy-methane platform (tris-CMPO). The terbium complex of tris-CMPS was crystallized and examined via X-ray structural analysis to provide valuable insight into the binding properties of the soft tripodal chelate. (authors)

  19. [Toxic nephropathy secondary to occupational exposure to metallic mercury].

    Science.gov (United States)

    Voitzuk, Ana; Greco, Vanina; Caputo, Daniel; Alvarez, Estela

    2014-01-01

    Toxic nephrophaties secondary to occupational exposure to metals have been widely studied, including membranous nephropathy by mercury, which is rare. Occupational poisoning by mercury is frequent, neurological symptoms are the main form of clinical presentation. Secondary renal involvement in chronic exposure to metallic mercury can cause glomerular disease by deposit of immune-complexes. Membranous glomerulopathy and minimal change disease are the most frequently reported forms. Here we describe the case of a patient with occupational exposure to metallic mercury, where nephrotic syndrome due to membranous glomerulonephritis responded favorably to both chelation and immunosuppressive therapy.

  20. On-load chelating agent treatments for conventional and nuclear power stations

    International Nuclear Information System (INIS)

    Turner, D.J.

    1978-01-01

    The paper is concerned with the application of on-load chelating agent treatments to those types of water circuit for which they are not currently available: high pressure drum boilers, sub-critical once-through boilers and water reactors. An attempt was made to see whether the most thermally stable types of chelating agent are likely to be sufficiently strong chelating agents either to dissolve established Fe 3 O 4 deposits or to prevent their precipitation from solution. It seems likely that they are strong enough to prevent Fe 3 O 4 depositing in a once-through boiler, through some may require that mildly reducing conditions are maintained. They would not be effective in a high pressure drum boiler (at 350 0 C) unless much more strongly reducing conditions could be maintained. For such boilers it would probably be better to seek multidentate ligands of less than maximum thermal stability. There are some indications that chelating agents based on carbon chains are more stable than NTA or EDTA so that citric acid or some of the unidentified chelating agents recently found to be produced radiolytically may have potential in the treatment of high pressure drum boilers. The prospects for periodic full-load cleaning seem less good for both types of boiler. There may also be a role for radiolytically produced chelating agents in alleviating some of the problems caused by the deposition of radioactive corrosion products in water reactor circuits. The chances for successful development fall from quite good to very low down the series SGHWR moderator circuit, PWR primary circuit, ammonia dosed BWR, neutral chemistry BWR (including SGHWR). (author)

  1. Biodegradation of metal citrate complexes and implications for toxic-metal mobility

    International Nuclear Information System (INIS)

    Francis, A.J.; Dodge, C.J.; Gillow, J.B.

    1992-01-01

    The presence of synthetic and naturally occurring chelating agents in nuclear and toxic-metal wastes is a major concern because of their potential to enhance mobilization of metal ions away from the disposal sites. Of particular interest is citric acid, which is present in low-level and transuranic radioactive wastes and in domestic and industrial wastes (as washing fluids, for instance), as well as being found naturally. Citrate ions form multidentate, stable complexes with a variety of toxic metals and radionuclides; but biodegradation of these complexes, precipitating the metal ions as insoluble hydroxides, oxides or other salts, may retard migration. Here we report a study of the biodegradation of citrate complexes of Ca, Fe(II), Fe(III), Cd, Cu, Ni, Pb and U. Several of these complexes were not readily degraded by bacteria, and the biodegradability depended on the chemical nature of the complex, not on the toxicity of the metal to the bacteria. This resistance to biodegradation implies that citrate complexation may play an important part in migration of these hazardous wastes. (author)

  2. Improved paramagnetic chelate for molecular imaging with MRI

    International Nuclear Information System (INIS)

    Winter, Patrick; Athey, Phillip; Kiefer, Garry; Gulyas, Gyongyi; Frank, Keith; Fuhrhop, Ralph; Robertson, David; Wickline, Samuel; Lanza, Gregory

    2005-01-01

    The relaxivity and transmetallation of two lipophilic paramagnetic chelates incorporated onto perfluorocarbon nanoparticles, i.e., gadolinium-methoxy-tetraazacyclododecane-tetraacetic acid phosphatidylethanolamine (Gd-MeO-DOTA-PE) and gadolinium-methoxy-tetraazacyclododecane-tetraacetic acid triglycine phosphatidylethanolamine (Gd-MeO-DOTA-triglycine-PE (Gd-MeO-DOTA-triglycine-PE)), were compared to a prototypic gadolinium-diethylene-triamine-pentaacetic acid bis-oleate (Gd-DTPA-BOA) paramagnetic formulation. Nanoparticles with MeO-DOTA-based chelates demonstrated higher relaxivity (40% higher for Gd-MeO-DOTA-PE and 55% higher for Gd-MeO-DOTA-triglycine-PE) and less transmetallation than the original Gd-DTPA-BOA-based agent

  3. Improved paramagnetic chelate for molecular imaging with MRI

    Science.gov (United States)

    Winter, Patrick; Athey, Phillip; Kiefer, Garry; Gulyas, Gyongyi; Frank, Keith; Fuhrhop, Ralph; Robertson, David; Wickline, Samuel; Lanza, Gregory

    2005-05-01

    The relaxivity and transmetallation of two lipophilic paramagnetic chelates incorporated onto perfluorocarbon nanoparticles, i.e., gadolinium-methoxy-tetraazacyclododecane-tetraacetic acid phosphatidylethanolamine (Gd-MeO-DOTA-PE) and gadolinium-methoxy-tetraazacyclododecane-tetraacetic acid triglycine phosphatidylethanolamine (Gd-MeO-DOTA-triglycine-PE (Gd-MeO-DOTA-triglycine-PE)), were compared to a prototypic gadolinium-diethylene-triamine-pentaacetic acid bis-oleate (Gd-DTPA-BOA) paramagnetic formulation. Nanoparticles with MeO-DOTA-based chelates demonstrated higher relaxivity (40% higher for Gd-MeO-DOTA-PE and 55% higher for Gd-MeO-DOTA-triglycine-PE) and less transmetallation than the original Gd-DTPA-BOA-based agent.

  4. Chelator induced phytoextraction and in situ soil washing of Cu

    International Nuclear Information System (INIS)

    Kos, Bostjan; Lestan, Domen

    2004-01-01

    In a soil column experiment, we investigated the effect of 5 mmol kg -1 soil addition of citric acid, ethylenediamine tetraacetate (EDTA), diethylenetriamine-pentaacetate (DTPA) and [S,S]-stereoisomer of ethylenediamine-disuccinate (EDDS) on phytoextraction of Cu from a vineyard soil with 162.6 mg kg -1 Cu, into the test plant Brassica rapa var. pekinensis. We also examined the use of a horizontal permeable barrier, composed of layers of nutrient enriched sawdust and apatite, for reduction of chelator induced Cu leaching. The addition of all chelators, except citric acid, enhanced Cu mobility and caused leaching of 19.5-23% of initial total Cu from the soil column. However, Cu plant uptake did not increase accordingly; the most effective was the EDDS treatment, in which plant Cu concentration reached 37.8±1.3 mg kg -1 Cu and increased by 3.3-times over the control treatment. The addition of none of the chelators in the concentration range from 5 to 15 mmol kg -1 exerted any toxic effect on respiratory soil microorganisms. When EDDS was applied into the columns with horizontal permeable barriers, only 0.53±0.32% of the initial total Cu was leached. Cu (36.7%) was washed from the 18 cm soil layer above the barrier and accumulated in the barrier. Our results indicate that rather than for a reduction of Cu leaching during rather ineffective chelate induced Cu phytoextraction, horizontal permeable barriers could be more effective in a new remediation technique of controlled in situ soil washing of Cu with biodegradable chelates

  5. Crystal-field energy level analysis for Nd3+ ions at the low symmetry C1 site in [Nd(hfa)4(H2O)](N(C2H5)4) single crystals

    International Nuclear Information System (INIS)

    Mech, Agnieszka; Gajek, Zbigniew; Karbowiak, Miroslaw; Rudowicz, Czeslaw

    2008-01-01

    Optical absorption measurements of Nd 3+ ions in single crystals of [Nd(hfa) 4 (H 2 O)](N(C 2 H 5 ) 4 ) (hfa = hexafluoroacetyloacetonate), denoted Nd(hfa) for short, have been carried out at 4.2 and 298 K. This compound crystallizes in the monoclinic system (space group P 2 1 /n). Each Nd ion is coordinated to eight oxygen atoms that originate from the hexafluoroacetylacetonate ligands and one oxygen atom from the water molecule. A total of 85 experimental crystal-field (CF) energy levels arising from the Nd 3+ (4f 3 ) electronic configuration were identified in the optical spectra and assigned. A three-step CF analysis was carried out in terms of a parametric Hamiltonian for the actual C 1 symmetry at the Nd 3+ ion sites. In the first step, a total of 27 CF parameters (CFPs) in the Wybourne notation B kq , admissible by group theory, were determined in a preliminary fitting constrained by the angular overlap model predictions. The resulting CFP set was reduced to 24 specific independent CFPs using appropriate standardization transformations. Optimizations of the second-rank CFPs and extended scanning of the parameter space were employed in the second step to improve reliability of the CFP sets, which is rather a difficult task in the case of no site symmetry. Finally, seven free-ion parameters and 24 CFPs were freely varied, yielding an rms deviation between the calculated energy levels and the 85 observed ones of 11.1 cm -1 . Our approach also allows prediction of the energy levels of Nd 3+ ions that are hidden in the spectral range overlapping with strong ligand absorption, which is essential for understanding the inter-ionic energy transfer. The orientation of the axis system associated with the fitted CF parameters w.r.t. the crystallographic axes is established. The procedure adopted in our calculations may be considered as a general framework for analysis of CF levels of lanthanide ions at low (triclinic) symmetry sites

  6. Crystal-field energy level analysis for Nd(3+) ions at the low symmetry C(1) site in [Nd(hfa)(4)(H(2)O)](N(C(2)H(5))(4)) single crystals.

    Science.gov (United States)

    Mech, Agnieszka; Gajek, Zbigniew; Karbowiak, Mirosław; Rudowicz, Czesław

    2008-09-24

    Optical absorption measurements of Nd(3+) ions in single crystals of [Nd(hfa)(4)(H(2)O)](N(C(2)H(5))(4)) (hfa = hexafluoroacetyloacetonate), denoted Nd(hfa) for short, have been carried out at 4.2 and 298 K. This compound crystallizes in the monoclinic system (space group P 2(1)/n). Each Nd ion is coordinated to eight oxygen atoms that originate from the hexafluoroacetylacetonate ligands and one oxygen atom from the water molecule. A total of 85 experimental crystal-field (CF) energy levels arising from the Nd(3+) (4f(3)) electronic configuration were identified in the optical spectra and assigned. A three-step CF analysis was carried out in terms of a parametric Hamiltonian for the actual C(1) symmetry at the Nd(3+) ion sites. In the first step, a total of 27 CF parameters (CFPs) in the Wybourne notation B(kq), admissible by group theory, were determined in a preliminary fitting constrained by the angular overlap model predictions. The resulting CFP set was reduced to 24 specific independent CFPs using appropriate standardization transformations. Optimizations of the second-rank CFPs and extended scanning of the parameter space were employed in the second step to improve reliability of the CFP sets, which is rather a difficult task in the case of no site symmetry. Finally, seven free-ion parameters and 24 CFPs were freely varied, yielding an rms deviation between the calculated energy levels and the 85 observed ones of 11.1 cm(-1). Our approach also allows prediction of the energy levels of Nd(3+) ions that are hidden in the spectral range overlapping with strong ligand absorption, which is essential for understanding the inter-ionic energy transfer. The orientation of the axis system associated with the fitted CF parameters w.r.t. the crystallographic axes is established. The procedure adopted in our calculations may be considered as a general framework for analysis of CF levels of lanthanide ions at low (triclinic) symmetry sites.

  7. Crystal-field energy level analysis for Nd3+ ions at the low symmetry C1 site in [Nd(hfa)4(H2O)](N(C2H5)4) single crystals

    Science.gov (United States)

    Mech, Agnieszka; Gajek, Zbigniew; Karbowiak, Mirosław; Rudowicz, Czesław

    2008-09-01

    Optical absorption measurements of Nd3+ ions in single crystals of [Nd(hfa)4(H2O)](N(C2H5)4) (hfa = hexafluoroacetyloacetonate), denoted Nd(hfa) for short, have been carried out at 4.2 and 298 K. This compound crystallizes in the monoclinic system (space group P 21/n). Each Nd ion is coordinated to eight oxygen atoms that originate from the hexafluoroacetylacetonate ligands and one oxygen atom from the water molecule. A total of 85 experimental crystal-field (CF) energy levels arising from the Nd3+ (4f3) electronic configuration were identified in the optical spectra and assigned. A three-step CF analysis was carried out in terms of a parametric Hamiltonian for the actual C1 symmetry at the Nd3+ ion sites. In the first step, a total of 27 CF parameters (CFPs) in the Wybourne notation Bkq, admissible by group theory, were determined in a preliminary fitting constrained by the angular overlap model predictions. The resulting CFP set was reduced to 24 specific independent CFPs using appropriate standardization transformations. Optimizations of the second-rank CFPs and extended scanning of the parameter space were employed in the second step to improve reliability of the CFP sets, which is rather a difficult task in the case of no site symmetry. Finally, seven free-ion parameters and 24 CFPs were freely varied, yielding an rms deviation between the calculated energy levels and the 85 observed ones of 11.1 cm-1. Our approach also allows prediction of the energy levels of Nd3+ ions that are hidden in the spectral range overlapping with strong ligand absorption, which is essential for understanding the inter-ionic energy transfer. The orientation of the axis system associated with the fitted CF parameters w.r.t. the crystallographic axes is established. The procedure adopted in our calculations may be considered as a general framework for analysis of CF levels of lanthanide ions at low (triclinic) symmetry sites.

  8. Development of a Novel Optical Biosensor for Detection of Organophoshorus Pesticides Based on Methyl Parathion Hydrolase Immobilized by Metal-Chelate Affinity

    Directory of Open Access Journals (Sweden)

    Wensheng Lan

    2012-06-01

    Full Text Available We have developed a novel optical biosensor device using recombinant methyl parathion hydrolase (MPH enzyme immobilized on agarose by metal-chelate affinity to detect organophosphorus (OP compounds with a nitrophenyl group. The biosensor principle is based on the optical measurement of the product of OP catalysis by MPH (p-nitrophenol. Briefly, MPH containing six sequential histidines (6× His tag at its N-terminal was bound to nitrilotriacetic acid (NTA agarose with Ni ions, resulting in the flexible immobilization of the bio-reaction platform. The optical biosensing system consisted of two light-emitting diodes (LEDs and one photodiode. The LED that emitted light at the wavelength of the maximum absorption for p-nitrophenol served as the signal light, while the other LED that showed no absorbance served as the reference light. The optical sensing system detected absorbance that was linearly correlated to methyl parathion (MP concentration and the detection limit was estimated to be 4 μM. Sensor hysteresis was investigated and the results showed that at lower concentration range of MP the difference got from the opposite process curves was very small. With its easy immobilization of enzymes and simple design in structure, the system has the potential for development into a practical portable detector for field applications.

  9. In vitro removal of toxic heavy metals by poly(γ-glutamic acid-coated superparamagnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Inbaraj BS

    2012-08-01

    Full Text Available Baskaran Stephen Inbaraj,1 Bing-Huei Chen1,21Department of Food Science, 2Graduate Institute of Medicine, Fu Jen University, Taipei, TaiwanBackground: Chelation therapy involving organic chelators for treatment of heavy metal intoxication can cause cardiac arrest, kidney overload, mineral deficiency, and anemia.Methods: In this study, superparamagnetic iron oxide nanoparticles (SPIONs modified with an edible biopolymer poly(γ-glutamic acid (PGA were synthesized by coprecipitation method, characterized and evaluated for their removal efficiency of heavy metals from a metal solution, and simulated gastrointestinal fluid (SGIF.Results: Instrumental characterization of bare- and PGA-SPIONs revealed 7% coating of PGA on SPIONs with a spherical shape and an iron oxide spinel structure belonging to magnetite. The particle sizes as determined from transmission electron microscopy images were 8.5 and 11.7 nm for bare- and PGA-SPIONs, respectively, while the magnetization values were 70.3 and 61.5 emu/g. Upon coating with PGA, the zeta potentials were shifted from positive to negative at most of the environmental pH (3–8 and biological pH (1–8, implying good dispersion in aqueous suspension and favorable conditions for heavy metal removal. Batch studies showed rapid removal of lead and cadmium with the kinetic rates estimated by pseudo-second-order model being 0.212 and 0.424 g/mg•min, respectively. A maximum removal occurred in the pH range 4–8 in deionized water and 5–8 in SGIF corresponding to most gastrointestinal pH except for the stomach. Addition of different ionic strengths (0.001–1 M sodium acetate and essential metals (Cu, Fe, Zn, Mg, Ca, and K did not show any marked influence on lead removal by PGA-SPIONs, but significantly reduced the binding of cadmium. Compared to deionized water, the lead removal from SGIF was high at all pH with the Langmuir monolayer removal capacity being 98.70 mg/g for the former and 147.71 mg/g for the

  10. Influence of structural and surface properties of whey-derived peptides on zinc-chelating capacity, and in vitro gastric stability and bioaccessibility of the zinc-peptide complexes.

    Science.gov (United States)

    Udechukwu, M Chinonye; Downey, Brianna; Udenigwe, Chibuike C

    2018-02-01

    Gastrointestinal stability of zinc-peptide complexes is essential for zinc delivery. As peptide surface charge can influence their metal complex stability, we evaluated the zinc-chelating capacity and stability of zinc complexes of whey protein hydrolysates (WPH), produced with Everlase (WPH-Ever; ζ-potential, -39mV) and papain (WPH-Pap; ζ-potential, -7mV), during simulated digestion. WPH-Ever had lower amount of zinc-binding amino acids but showed higher zinc-chelating capacity than WPH-Pap. This is attributable to the highly anionic surface charge of WPH-Ever for electrostatic interaction with zinc. Release of zinc during peptic digestion was lower for WPH-Ever-zinc, and over 50% of zinc remained bound in both peptide complexes after peptic-pancreatic digestion. Fourier transform infrared spectroscopy suggests the involvement of carboxylate ion, and sidechain carbon-oxygen of aspartate/glutamate and serine/threonine in zinc-peptide complexation. The findings indicate that strong zinc chelation can promote gastric stability and impede intestinal release, for peptides intended for use as dietary zinc carriers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Macrocyclic receptor showing extremely high Sr(II)/Ca(II) and Pb(II)/Ca(II) selectivities with potential application in chelation treatment of metal intoxication.

    Science.gov (United States)

    Ferreirós-Martínez, Raquel; Esteban-Gómez, David; Tóth, Éva; de Blas, Andrés; Platas-Iglesias, Carlos; Rodríguez-Blas, Teresa

    2011-04-18

    these metal ions are exocyclically coordinated by the ligand, which explains the high Pb(II)/Cd(II) and Pb(II)/Zn(II) selectivities. Our receptor bp18c6(2-) shows promise for application in chelation treatment of metal intoxication by Pb(II) and (90)Sr(II).

  12. Which psychosocial factors are related to chelation adherence in thalassemia? A systematic review.

    Science.gov (United States)

    Evangeli, Michael; Mughal, Kulsoom; Porter, John B

    2010-06-01

    Good adherence to iron chelation therapy in thalassemia is crucial. Although there is evidence that adherence is related to regimen factors, there has been less emphasis on the relationship between psychosocial (psychological, demographic and social) factors and adherence. We present a systematic review of psychosocial correlates of chelation adherence in thalassemia. Nine studies met the inclusion criteria. Information was extracted regarding the study characteristics and the relationship between psychosocial factors and chelation adherence. Methodological quality was rated. The studies took place in a range of countries, were mostly cross sectional in design, and examined adherence to deferoxamine (DFO) only. Sample sizes ranged from 15 to 1573. A variety of psychosocial variables were examined. Definitions of adherence varied between studies and non adherence rates were also variable (9 to 66%). Older age was consistently associated with lower levels of chelation adherence. There were few other consistent findings. The methodological quality of studies was variable. There is a need for more methodologically sophisticated and theoretically informed studies on psychosocial correlates of chelation adherence. We offer specific suggestions.

  13. Coordination of two high-affinity hexamer peptides to copper(II) and palladium(II) models of the peptide-metal chelation site on IMAC resins.

    Science.gov (United States)

    Chen, Y; Pasquinelli, R; Ataai, M; Koepsel, R R; Kortes, R A; Shepherd, R E

    2000-03-20

    The coordination of peptides Ser-Pro-His-His-Gly-Gly (SPHHGG) and (His)6 (HHHHHH) to [PdII(mida)(D2O)] (mida2- = N-methyliminodiacetate) was studied by 1H NMR as model reactions for CuII(iminodiacetate)-immobilized metal affinity chromatography (IMAC) sites. This is the first direct physical description of peptide coordination for IMAC. A three-site coordination is observed which involves the first, third, and fourth residues along the peptide chain. The presence of proline in position 2 of SPHHGG achieves the best molecular mechanics and bonding angles in the coordinated peptide and enhances the interaction of the serine amino nitrogen. Histidine coordination of H1, H3, and H4 of (His)6 and H3 and H4 of SPHHGG was detected by 1H NMR contact shifts and H/D exchange of histidyl protons. The EPR spectra of SPHHGG and HHHHHH attached to the [CuII(mida)] unit were obtained for additional modeling of IMAC sites. EPR parameters of the parent [Cu(mida)(H2O)2] complex are representative: gzz = 2.31; gyy = 2.086; gxx = 2.053; A parallel = 161G; AN = 19G (three line, one N coupling). Increased rhombic distortion is detected relative to the starting aqua complex in the order of [Cu(mida)L] for distortion of HHHHHH > SPHHGG > (H2O)2. The lowering of symmetry is also seen in the decrease in the N-shf coupling, presumably to the imino nitrogen of mida2- in the order 19 G (H2O), 16 G (SPHHGG) and 11 G (HHHHHH). Visible spectra of the [Cu(mida)(SPHHGG)] and [Cu(mida)(HHHHHH)] as a function of pH indicate coordination of one histidyl donor at ca. 4.5, two in the range of pH 5-7, and two chelate ring attachments involving the terminal amino donor for SPHHGG or another histidyl donor of HHHHHH in the pH domain of 7-8 in agreement with the [PdII(mida)L] derivatives which form the two-chelate-ring attachment even at lower pH as shown by the 1H NMR methods.

  14. Chelating agent-free, vapor-assisted crystallization method to synthesize hierarchical microporous/mesoporous MIL-125 (Ti).

    Science.gov (United States)

    McNamara, Nicholas D; Hicks, Jason C

    2015-03-11

    Titanium-based microporous heterogeneous catalysts are widely studied but are often limited by the accessibility of reactants to active sites. Metal-organic frameworks (MOFs), such as MIL-125 (Ti), exhibit enhanced surface areas due to their high intrinsic microporosity, but the pore diameters of most microporous MOFs are often too small to allow for the diffusion of larger reactants (>7 Å) relevant to petroleum and biomass upgrading. In this work, hierarchical microporous MIL-125 exhibiting significantly enhanced interparticle mesoporosity was synthesized using a chelating-free, vapor-assisted crystallization method. The resulting hierarchical MOF was examined as an active catalyst for the oxidation of dibenzothiophene (DBT) with tert-butyl hydroperoxide and outperformed the solely microporous analogue. This was attributed to greater access of the substrate to surface active sites, as the pores in the microporous analogues were of inadequate size to accommodate DBT. Moreover, thiophene adsorption studies suggested the mesoporous MOF contained larger amounts of unsaturated metal sites that could enhance the observed catalytic activity.

  15. Chelation of thallium by combining deferasirox and desferrioxamine in rats.

    Science.gov (United States)

    Saljooghi, Amir Shokooh; Babaie, Maryam; Mendi, Fatemeh Delavar; Zahmati, Maliheh; Saljooghi, Zoheir Shokouh

    2016-01-01

    The hypothesis that two known chelators deferasirox (4-[3,5-bis(2-hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid) and desferrioxamine (DFO) might be more efficient as combined treatment than as monotherapies in removing thallium from the body was tested in a new acute rat model. 7-week-old male Wistar rats received chelators: deferasirox (orally), DFO (intraperitoneal; i.p.), or deferasirox + DFO as 75 or 150 mg/kg dose half an hour after a single i.p. administration of 8 mg thallium/kg body weight in the form of chloride. Serum thallium concentration, urinary thallium, and iron excretions were determined by graphite furnace atomic absorption spectrometry. Both chelators were effective only at the higher dose level, while DFO was more effective than deferasirox in enhancing urinary thallium excretion, deferasirox was more effective than DFO in enhancing urinary iron excretion. In the combined treatment group, deferasirox did not increase the DFO effect on thallium and DFO did not increase the effect of deferasirox on iron elimination. Our results support the usefulness of this animal model for preliminary in vivo testing of thallium chelators. Urinary values were more useful because of the high variability of serum results. © The Author(s) 2013.

  16. Chelation therapy in intoxications with mercury, lead and copper

    DEFF Research Database (Denmark)

    Cao, yang; Skaug, Marit Aralt; Andersen, Ole

    2015-01-01

    In the present review we provide an update of the appropriate use of chelating agents in the treatment of intoxications with compounds of mercury, lead and copper. The relatively new chelators meso-2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercapto-propanesulphonate (DMPS) can effectively...... mobilize deposits of mercury as well as of lead into the urine. These drugs can be administered orally and have relatively low toxicity compared to the classical antidote dimercaptopropanol (BAL). d-Penicillamine has been widely used in copper overload, although 2,3-dimercaptosuccinic acid...

  17. Removal and Remediation Effects of Cd from Cadmium-contaminated Farmland Soils by A Magnetic Solid Chelator

    Directory of Open Access Journals (Sweden)

    NIE Xin-xing

    2017-10-01

    Full Text Available In this paper, a simulated experiment was carried out to study the removal and remediation effects of Cd from cadmium-contaminated farmland soils by a magnetic solid chelator(MSC at different application rates as well as its recovery rates and chelating capacity for Cd. The results showed that when the application rates of MSC materials was between 0.4% and 1.2%, the removal rate of total Cd and available Cd were 15.91%~17.69% and 33.33%~50.26%, respectively. And the MSC recovery rates were between 74.01% and 94.33% which increased with the increase of application rates of MSC and gradually tended to be stable. The content of Cd in recycled magnetic materials(mainly MSC was between 19.31 mg·kg-1 to 25.72 mg·kg-1, reaching to the highest at the application rates of 0.4% which was significantly higher than those of 0.8%, 1% and 1.2% treatment. But the content of Cd in magnetic materials had the trend that decreased with the increase of the recovery amount of MSC. The amount of Cd chelated by magnetic materials was nearly equal to the removal amount of Cd from soil at the 0.8% and 1.2% treatments. Besides, the Cd concentration in water samples was lower thanⅠ-level standard issued by the surface water environment quality standard(GB 3838-2002, meaning that it would not be a new pollution source. Therefore, MSC does have some removal and remediation effects on soil Cd and will provide a new method for remediation of heavy metals in farmland soils.

  18. Application of liquid column chromatography to preconcentration, separation and determination of platinum metals

    International Nuclear Information System (INIS)

    Alimarin, I.P.; Basova, E.M.; Bol'shova, T.A.; Ivanov, V.M.

    1986-01-01

    Separation and determination of platimum metals using the methods of adsorption, ion-pair, ion-exchange, distributing and sieve chromatography are discussed in the review of literature in 1971-1984. Separation and determination of metals as chelates using the method of adsorption and ion-pair chromatograpy are noted to be most perspective directions of developing highly effective liquid chromatography of inorganic systems

  19. Recovery and utilization of valuable metals from spent nuclear fuel. 3: Mutual separation of valuable metals

    International Nuclear Information System (INIS)

    Kirishima, K.; Shibayama, H.; Nakahira, H.; Shimauchi, H.; Myochin, M.; Wada, Y.; Kawase, K.; Kishimoto, Y.

    1993-01-01

    In the project ''Recovery and Utilization of Valuable Metals from Spent Fuel,'' mutual separation process of valuable metals recovered from spent fuel has been studied by using the simulated solution contained Pb, Ru, Rh, Pd and Mo. Pd was separated successfully by DHS (di-hexyl sulfide) solvent extraction method, while Pb was recovered selectively from the raffinate by neutralization precipitation of other elements. On the other hand, Rh was roughly separated by washing the precipitate with alkaline solution, so that Rh was refined by chelate resin CS-346. Outline of the mutual separation process flow sheet has been established of the combination of these techniques. The experimental results and the process flow sheet of mutual separation of valuable metals are presented in this paper

  20. Toxicity of copper chelates of azomethines and amino acids for Chlorella pyrenoidosa

    Energy Technology Data Exchange (ETDEWEB)

    Barashkov, G.K.; Rukhadze, E.G.; Talyzenkova, G.P.

    1979-01-01

    The authors have attempted to assess the toxicity of copper-containing compounds from the point of view of their interrelationship with the structural characteristics of the chelate compound and the structure of the ligand. The copper chelates of the azomethines tested may be provisionally divided into three types: A - complexes with N-alkly-azomethines; B - complexes with N-aryl-azomethines; C - binuclear complexes. Consideration was also given to chelates with aromatic and heterocyclic amino acids and to heteroligand chelates in which the copper atom coordinates azomethine and an amino acid simultaneously. Toxicity was determined by the method previously described and expressed as a critical concentration (C/sub cr/, mg Cu/liter) and in relative toxicity units (T/sub c/). The compounds investigated were obtained from the interaction between a bidentant ligand of an azomethine or anamino acid and copper acetate in a water-alcohol medium at pH 6-8. Since they are not very soluble in water, true solutions were obtained by using dimethyl sulfoxide.

  1. The influence of EDDS and EDTA on the uptake of heavy metals of Cd and Cu from soil with tobacco Nicotiana tabacum.

    Science.gov (United States)

    Evangelou, Michael W H; Bauer, Uwe; Ebel, Mathias; Schaeffer, Andreas

    2007-06-01

    Phytoextraction, the use of plants to extract contaminants from soils and groundwater, is a promising approach for cleaning up soils contaminated with heavy metals. In order to enhance phytoextraction the use of chelating agents has been proposed. This study aims to assess whether ethylene diamine disuccinate (EDDS), a biodegradable chelator, can be used for enhanced phytoextraction purposed, as an alternative to ethylene diamine tetraacetate (EDTA). EDDS revealed a higher toxicity to tobacco (Nicotiana tabacum) in comparison to EDTA, but no toxicity to microorganisms. The uptake of Cu was increased by the addition of EDTA and EDDS, while no increase was observed in the uptake of Cd. Both chelating agents showed a very low root to shoot translocation capability and the translocation factor was lower than the one of the control. Heavy metals where significantly more phytoavailable than in the control, even after harvesting, resulting in a high heavy metal leaching possibility, probably owing to a low biodegradation rate of EDDS. New seedlings which were transplanted into the EDDS treated pots 7d after the phytoextraction experiment, showed signs of necrosis and chlorosis, which resulted in a significantly lower biomass in comparison to the control. The seedlings on the EDTA treated pots showed no toxicity signs. Contrary to previous opinions the results of this study revealed the chelating agents EDTA and EDDS as unsuitable for enhanced phytoextraction using tobacco.

  2. A detailed in vitro study of naproxen metal complexes in quest of ...

    African Journals Online (AJOL)

    Antioxidant potential was evaluated in terms of DPPH radical scavenging potential, ABTS scavenging potential, reducing power assay, superoxide dismutase assay and total antioxidant capacity by specific standard procedures. Results: The Naproxen metal chelates showed significant anti-inflammatory effects in dose ...

  3. Coupling fast water exchange to slow molecular tumbling in Gd3+ chelates: why faster is not always better.

    Science.gov (United States)

    Avedano, Stefano; Botta, Mauro; Haigh, Julian S; Longo, Dario L; Woods, Mark

    2013-08-05

    The influence of dynamics on solution state structure is a widely overlooked consideration in chemistry. Variations in Gd(3+) chelate hydration with changing coordination geometry and dissociative water exchange kinetics substantially impact the effectiveness (or relaxivity) of monohydrated Gd(3+) chelates as T1-shortening contrast agents for MRI. Theory shows that relaxivity is highly dependent upon the Gd(3+)-water proton distance (rGdH), and yet this distance is almost never considered as a variable in assessing the relaxivity of a Gd(3+) chelate as a potential contrast agent. The consequence of this omission can be seen when considering the relaxivity of isomeric Gd(3+) chelates that exhibit different dissociative water exchange kinetics. The results described herein show that the relaxivity of a chelate with "optimal" dissociative water exchange kinetics is actually lower than that of an isomeric chelate with "suboptimal" dissociative water exchange. When the rate of molecular tumbling of these chelates is slowed, an approach that has long been understood to increase relaxivity, the observed difference in relaxivity is increased with the more rapidly exchanging ("optimal") chelate exhibiting lower relaxivity than the "suboptimally" exchanging isomer. The difference between the chelates arises from a non-field-dependent parameter: either the hydration number (q) or rGdH. For solution state Gd(3+) chelates, changes in the values of q and rGdH are indistinguishable. These parametric expressions simply describe the hydration state of the chelate--i.e., the number and position of closely associating water molecules. The hydration state (q/rGdH(6)) of a chelate is intrinsically linked to its dissociative water exchange rate kex, and the interrelation of these parameters must be considered when examining the relaxivity of Gd(3+) chelates. The data presented herein indicate that the changes in the hydration parameter (q/rGdH(6)) associated with changing dissociative

  4. Arsenic Removal from Pinctada martensii Enzymatic Hydrolysate by Using Zr(Ⅳ)-Loaded Chelating Resin

    Institute of Scientific and Technical Information of China (English)

    YANG Xiaoman; DAI Wenjin; SUN Huili; PAN Jianyu

    2013-01-01

    The present study investigated the removal of inorganic arsenic from Pinctada martensii enzymatic hydrolysate through unmodified resin (D296) and Zr(Ⅳ)-loaded chelating resin (Zr-D401).By loading Zr to macroporous chelating resin D401,the as exchange adsorption active sites are generated.This transforms D401 from a material that does not have the arsenic adsorption capacity into a material that has excellent arsenic exchange adsorption capacity.The static adsorption experiments were conducted to investigate the optimal removal condition for D296 and Zr-D401.The experimental results show that:the optimum condition for D296 is that T=25℃,pH=5,resin additive amount=1 g(50mL)-1,and contact time=10h,the corresponding arsenic removal rate being 65.7%,and protein loss being 2.33%; the optimum condition for Zr-D401 is that T=25 ℃,pH=8,resin additive amount=1 g (50 mL)-1,and contact time=10 h,the corresponding arsenic removal rate being 70.3%,and protein loss being 4.65%.These results show that both of the two resins are effective in arsenic removal for preserving useful substance.Our research provides scientific evidence and advances in the processing technology for heavy metal removal in shellfish.

  5. Synthesis, characterization and metal coordination of a potential β-lactamase inhibitor: 5-Methyl-2-phenoxymethyl-3-H-imidazole-4-carboxylic acid (PIMA

    Directory of Open Access Journals (Sweden)

    Chiara Romagnoli

    2017-12-01

    Full Text Available Among relevant metal ions in biological systems, zinc and iron play a key role as active partners of the catalytic machinery. In particular, the inhibition of metal enzymes that are involved in physiological and pathological processes has been deeply investigated for the rational design of selective and efficient drugs based on chelators. Since imidazole histidine residue is one of the most versatile sites in proteins, especially in enzymes acting in the presence of metal ions as cofactors, in this work the synthesis and characterization of a new imidazole derivative, namely 5-methyl-2-phenoxymethyl-3-H-imidazole-4-carboxylic acid (PIMA is reported. PIMA was designed as metallo-β-lactamase inhibitor thanks to its similarity with penicillin V, a β-lactam antibiotic inactivated by metallo-β-lactamase, for which there are no commercially available inhibitors. The evaluation of PIMA coordinating ability toward iron, zinc, and gallium, these latter selected as a non-paramagnetic probe for iron, is performed by theoretical DFT calculations and in solution by experimental techniques, i.e. potentiometry, UV–vis and NMR spectroscopy. PIMA exhibits an efficient metal chelating ability; the prevailing species in physiological condition are ML3 for Fe3+ and Ga3+ and ML2 for Zn2+, in which chelation is due to deprotonated carboxylic oxygen and imidazole nitrogen in the N,O donor set. The demonstrated ability of PIMA to chelate zinc ion, combined with its structure similarity with penicillin V, supports further exploration of this imidazole-4-carboxylate as metallo-β-lactamase inhibitor.

  6. Oxidative degradation stability and hydrogen sulfide removal performance of dual-ligand iron chelate of Fe-EDTA/CA.

    Science.gov (United States)

    Miao, Xinmei; Ma, Yiwen; Chen, Zezhi; Gong, Huijuan

    2017-09-05

    Catalytic oxidation desulfurization using chelated iron catalyst is an effective method to remove H 2 S from various gas streams including biogas. However, the ligand of ethylenediaminetetraacetic acid (EDTA), which is usually adopted to prepare chelated iron catalyst, is liable to be oxidative degraded, and leads to the loss of desulfurization performance. In order to improve the degradation stability of the iron chelate, a series of iron chelates composed of two ligands including citric acid (CA) and EDTA were prepared and the oxidative degradation stability as well as desulfurization performance of these chelated iron catalysts were studied. Results show that the iron chelate of Fe-CA is more stable than Fe-EDTA, while for the desulfurization performance, the situation is converse. For the dual-ligand iron chelates of Fe-EDTA/CA, with the increase of mol ratio of CA to EDTA in the iron chelate solution, the oxidative degradation stability increased while the desulfurization performance decreased. The results of this work showed that Fe-EDTA/CA with a mol ratio of CA:EDTA = 1:1 presents a relative high oxidative degradation stability and an acceptable desulfurization performance with over 90% of H 2 S removal efficiency.

  7. Mathematical modeling of the effects of aerobic and anaerobic chelate biodegradation on actinide speciation

    International Nuclear Information System (INIS)

    Banaszak, J.E.; VanBriesen, J.; Rittmann, B.E.; Reed, D.T.

    1998-01-01

    Biodegradation of natural and anthropogenic chelating agents directly and indirectly affects the speciation, and, hence, the mobility of actinides in subsurface environments. We combined mathematical modeling with laboratory experimentation to investigate the effects of aerobic and anaerobic chelate biodegradation on actinide [Np(IV/V), Pu(IV)] speciation. Under aerobic conditions, nitrilotriacetic acid (NTA) biodegradation rates were strongly influenced by the actinide concentration. Actinide-chelate complexation reduced the relative abundance of available growth substrate in solution and actinide species present or released during chelate degradation were toxic to the organisms. Aerobic bio-utilization of the chelates as electron-donor substrates directly affected actinide speciation by releasing the radionuclides from complexed form into solution, where their fate was controlled by inorganic ligands in the system. Actinide speciation was also indirectly affected by pH changes caused by organic biodegradation. The two concurrent processes of organic biodegradation and actinide aqueous chemistry were accurately linked and described using CCBATCH, a computer model developed at Northwestern University to investigate the dynamics of coupled biological and chemical reactions in mixed waste subsurface environments. CCBATCH was then used to simulate the fate of Np during anaerobic citrate biodegradation. The modeling studies suggested that, under some conditions, chelate degradation can increase Np(IV) solubility due to carbonate complexation in closed aqueous systems

  8. Mathematical modelling of the effects of aerobic and anaerobic chelate biodegradation on actinide speciation

    International Nuclear Information System (INIS)

    Banaszak, J.E.; VanBriesen, J.M.; Rittmann, B.E.; Reed, D.T.

    1998-01-01

    Biodegradation of natural and anthropogenic chelating agents directly and indirectly affects the speciation, and hence, the mobility of actinides in subsurface environments. We combined mathematical modelling with laboratory experimentation to investigate the effects of aerobic and anaerobic chelate biodegradation on actinide [Np(IV/V), Pu(IV)] speciation. Under aerobic conditions, nitrilotriacetic acid (NTA) biodegradation rates were strongly influenced by the actinide concentration. Actinide-chelate complexation reduced the relative abundance of available growth substrate in solution and actinide species present or released during chelate degradation were toxic to the organisms. Aerobic bioutilization of the chelates as electron-donor substrates directly affected actinide speciation by releasing the radionuclides from complexed form into solution, where their fate was controlled by inorganic ligands in the system. Actinide speciation was also indirectly affected by pH changes caused by organic biodegradation. The two concurrent processes of organic biodegradation and actinide aqueous chemistry were accurately linked and described using CCBATCH, a computer model developed at Northwestern University to investigate the dynamics of coupled biological and chemical reactions in mixed waste subsurface environments. CCBATCH was then used to simulate the fate of Np during anaerobic citrate biodegradation. The modelling studies suggested that, under some conditions, chelate degradation can increase Np(IV) solubility due to carbonate complexation in closed aqueous systems. (orig.)

  9. Ionochromic effects and structures of metalated poly(p-phenylenevinylene) polymers incorporating 2,2'-bipyridines

    International Nuclear Information System (INIS)

    Chen, L.X.; Jager, W.J.H.; Gosztola, D.J.; Niemczyk, M.P.; Wasielewski, M.R.

    2000-01-01

    The effects of metal ion chelation to the 2,2'-bipyridine (bpy) groups on the photophysics and exciton dynamics of two conjugated polymers 1 and 2 in solution are investigated. The structures of polymers 1 and 2 have 2,2'-bipyridyl-5-vinylene units that alternate with one and three 2,5-bis(n-decyloxy)-1,4-phenylenevinylene monomer units, respectively. The photophysics and exciton dynamics of metalated polymers 1 and 2 are compared to those of the metal-free polymers (Chen et al. J. Phys. Chem. A 1999, 103, 4341-4351). The origins of ionochromic effects due the metal ion chelation were studied using both steady-state and transient optical spectroscopy, and the results indicate that both conformational flattening and participation of Jr electrons from the metal in the π-conjugation of the polymer backbone play important roles in metal ion binding induced red shifts in absorption and photoluminescence spectra. The photoluminescence properties of the metalated polymers are determined by the metal ion electronic structures, where the closed shell Zn 2+ -bound polymer 2 has an increased photoluminescence quantum yield and the corresponding open shell Ni 2+ - or Fe 3+ -bound polymers have quenched photoluminescence due to spin-orbit coupling. The dual character of metalated polymer 2 as a conjugated polymer and as a metal-bpy complex is discussed. In addition, the structures of metal ion binding sites are studied via X-ray absorption fine structure (XAFS) and are related to the photophysical properties of the metalated polymers

  10. Recent advances in the ruthenium(ii)-catalyzed chelation-assisted C-H olefination of substituted aromatics, alkenes and heteroaromatics with alkenes via the deprotonation pathway.

    Science.gov (United States)

    Manikandan, Rajendran; Jeganmohan, Masilamani

    2017-08-08

    The transition-metal-catalyzed chelation-assisted alkenylation at the inert C-H bond of aromatics with alkenes is one of the efficient methods to synthesize substituted vinylarenes in a highly regio- and stereoselective manner. Palladium, rhodium and ruthenium complexes are frequently used as catalysts for this type of transformation. The present review describes the recent advances in the ruthenium-catalyzed chelation-assisted alkenylation at the C-H bond of aromatics, alkenes and heteroaromatics with alkenes via the deprotonation pathway. Several directing groups including 2-pyridyl, carbonyl, amidine, amide, amine, imidate, sulphonic acid, triazole, cyano, oxazolidinone and hydontoin are widely used in the reaction. The scope, limitation and mechanistic investigation of the alkenylation reactions are discussed elaborately. This feature article includes all the reported ruthenium-catalyzed alkenylation reactions via the deprotonation pathway until the end of March 2017.

  11. Femtomolar Ln(III) affinity in peptide-based ligands containing unnatural chelating amino acids.

    Science.gov (United States)

    Niedźwiecka, Agnieszka; Cisnetti, Federico; Lebrun, Colette; Delangle, Pascale

    2012-05-07

    The incorporation of unnatural chelating amino acids in short peptide sequences leads to lanthanide-binding peptides with a higher stability than sequences built exclusively from natural residues. In particular, the hexadentate peptide P(22), which incorporates two unnatural amino acids Ada(2) with aminodiacetate chelating arms, showed picomolar affinity for Tb(3+). To design peptides with higher denticity, expected to show higher affinity for Ln(3+), we synthesized the novel unnatural amino acid Ed3a(2) which carries an ethylenediamine triacetate side-chain and affords a pentadentate coordination site. The synthesis of the derivative Fmoc-Ed3a(2)(tBu)(3)-OH, with appropriate protecting groups for direct use in the solid phase peptide synthesis (Fmoc strategy), is described. The two high denticity peptides P(HD2) (Ac-Trp-Ed3a(2)-Pro-Gly-Ada(2)-Gly-NH(2)) and P(HD5) (Ac-Trp-Ada(2)-Pro-Gly-Ed3a(2)-Gly-NH(2)) led to octadentate Tb(3+) complexes with femtomolar stability in water. The position of the high denticity amino acid Ed3a(2) in the hexapeptide sequence appears to be critical for the control of the metal complex speciation. Whereas P(HD5) promotes the formation of polymetallic species in excess of Ln(3+), P(HD2) forms exclusively the mononuclear complex. The octadentate coordination of Tb(3+) by both P(HD) leads to total dehydration of the metal ion in the mononuclear complexes with long luminescence lifetimes (>2 ms). Hence, we demonstrated that unnatural amino acids carrying polyaminocarboxylate side-chains are interesting building blocks to design high affinity Ln-binding peptides. In particular the novel peptide P(HD2) forms a unique octadentate Tb(3+) complex with femtomolar stability in water and an improvement of the luminescence properties with respect to the trisaquo TbP(22) complex by a factor of 4.

  12. Characterization of the effect of serum and chelating agents on Staphylococcus aureus biofilm formation; chelating agents augment biofilm formation through clumping factor B

    Science.gov (United States)

    Abraham, Nabil Mathew

    Staphylococcus aureus is the causative agent of a diverse array of acute and chronic infections, and some these infections, including infective endocarditis, joint infections, and medical device-associated bloodstream infections, depend upon its capacity to form tenacious biofilms on surfaces. Inserted medical devices such as intravenous catheters, pacemakers, and artificial heart valves save lives, but unfortunately, they can also serve as a substrate on which S. aureus can form a biofilm, attributing S. aureus as a leading cause of medical device-related infections. The major aim of this work was take compounds to which S. aureus would be exposed during infection and to investigate their effects on its capacity to form a biofilm. More specifically, the project investigated the effects of serum, and thereafter of catheter lock solutions on biofilm formation by S. aureus. Pre-coating polystyrene with serum is frequently used as a method to augment biofilm formation. The effect of pre-coating with serum is due to the deposition of extracellular matrix components onto the polystyrene, which are then recognized by MSCRAMMs. We therefore hypothesized that the major component of blood, serum, would induce biofilm formation. Surprisingly, serum actually inhibited biofilm formation. The inhibitory activity was due to a small molecular weight, heat-stable, non-proteinaceous component/s of serum. Serum-mediated inhibition of biofilm formation may represent a previously uncharacterized aspect of host innate immunity that targets the expression of a key bacterial virulence factor: the ability to establish a resistant biofilm. Metal ion chelators like sodium citrate are frequently chosen to lock intravenous catheters because they are regarded as potent inhibitors of bacterial biofilm formation and viability. We found that, while chelating compounds abolished biofilm formation in most strains of S. aureus, they actually augmented the phenotype in a subset of strains. We

  13. Red Blood Cell Transfusion Independence Following the Initiation of Iron Chelation Therapy in Myelodysplastic Syndrome

    Directory of Open Access Journals (Sweden)

    Maha A. Badawi

    2010-01-01

    Full Text Available Iron chelation therapy is often used to treat iron overload in patients requiring transfusion of red blood cells (RBC. A 76-year-old man with MDS type refractory cytopenia with multilineage dysplasia, intermediate-1 IPSS risk, was referred when he became transfusion dependent. He declined infusional chelation but subsequently accepted oral therapy. Following the initiation of chelation, RBC transfusion requirement ceased and he remained transfusion independent over 40 months later. Over the same time course, ferritin levels decreased but did not normalize. There have been eighteen other MDS patients reported showing improvement in hemoglobin level with iron chelation; nine became transfusion independent, nine had decreased transfusion requirements, and some showed improved trilineage myelopoiesis. The clinical features of these patients are summarized and possible mechanisms for such an effect of iron chelation on cytopenias are discussed.

  14. Reaction of gadolinium chelates with ozone and hydroxyl radicals.

    Science.gov (United States)

    Cyris, Maike; Knolle, Wolfgang; Richard, Jessica; Dopp, Elke; von Sonntag, Clemens; Schmidt, Torsten C

    2013-09-03

    Gadolinium chelates are used in increasing amounts as contrast agents in magnetic resonance imaging, and their fate in wastewater treatment has recently become the focus of research. Oxidative processes, in particular the application of ozone, are currently discussed or even implemented for advanced wastewater treatment. However, reactions of the gadolinium chelates with ozone are not yet characterized. In this study, therefore, rate constants with ozone were determined for the three commonly used chelates Gd-DTPA, Gd-DTPA-BMA, and Gd-BT-DO3A, which were found to be 4.8 ± 0.88, 46 ± 2.5, and 24 ± 1.5 M(-1) s(-1), respectively. These low rate constants indicate that a direct reaction with ozone in wastewater is negligible. However, application of ozone in wastewater leads to substantial yields of (•)OH. Different methods have been applied and compared for determination of k((•)OH+Gd chelate). From rate constants determined by pulse radiolysis experiments (k((•)OH+Gd-DTPA) = 2.6 ± 0.2 × 10(9) M(-1) s(-1), k((•)OH+Gd-DTPA-BMA) = 1.9 ± 0.7 × 10(9) M(-1) s(-1), k((•)OH+Gd-BT-DO3A) = 4.3 ± 0.2 × 10(9) M(-1) s(-1)), it is concluded that a reaction in wastewater via (•)OH radicals is feasible. Toxicity has been tested for educt and product mixtures of both reactions. Cytotoxicity (MTT test) and genotoxicity (micronuclei assay) were not detectable.

  15. Adsorption of heavy metal ions and azo dyes by crosslinked nanochelating resins based on poly(methylmethacrylate-co-maleic anhydride

    Directory of Open Access Journals (Sweden)

    M. Ghaemy

    2014-03-01

    Full Text Available Chelating resins are suitable materials for the removal of heavy metals in water treatments. A copolymer, Poly(MMA-co-MA, was synthesized by radical polymerization of maleic anhydride (MA and methyl methacrylate (MMA, characterized and transformed into multifunctional nanochelating resin beads (80–150 nm via hydrolysis, grafting and crosslink reactions. The resin beads were characterized by swelling studies, field emission scanning electron microscopy (FESEM and Fourier transform infrared spectroscopy (FTIR. The main purpose of this work was to determine the adsorption capacity of the prepared resins (swelling ratio ~55% towards metal ions such as Hg2+, Cd2+, Cu2+ from water at three different pH values (3, 6 and 9. Variations in pH and types of metal ions have not significantly affected the chelation capacity of these resins. The maximum chelation capacity of one of the prepared resin beads (Co-g-AP3 for Hg2+ was 63, 85.8 and 71.14 mg/g at pH 3, 6 and 9, respectively. Approximately 96% of the metal ions could be desorbed from the resin. Adsorption capacity of these resins towards three commercial synthetic azo dyes was also investigated. The maximum adsorption of dye AY42 was 91% for the resin Co-g-AP3 at room temperature. This insures the applicability of the synthesized resins for industrial applications.

  16. Chelation-Assisted Substrate-Controlled Asymmetric Lithiation-Allylboration of Chiral Carbamate 1,2,4-Butanetriol Acetonide

    Directory of Open Access Journals (Sweden)

    Adeem Mahmood

    2015-05-01

    Full Text Available The lithiation of 2-(2,2-dimethyl-1,3-dioxolan-4-ylethyl diisopropylcarbamate (1 is achieved freely by sec-butyllithium in diethylether with high lk-diastereoselectivity: the bicyclic chelate complexes 3a and 3b are reacted with electrophiles to form optically active precursors 4a and 4b with >95% diastereoselectivity. In addition, tertiary diamines can undergo an external complexation in contest with the internal oxygen ligand, leading to improved stereoselectivities. The further reactions of lithiated carbamates with trans alkenyl-9-BBN derivatives after 1,2 metallate rearrangements, gave the key intermediate α-substituted allylic boranes 7. Subsequent allylboration of aldehydes gave (Z-anti-homoallylic alcohols 8 in good yield and excellent d.r.

  17. Removal and recovery of metal ions from process and waste streams using polymer filtration

    International Nuclear Information System (INIS)

    Jarvinen, G.D.; Smith, B.F.; Robison, T.W.; Kraus, K.M.; Thompson, J.A.

    1999-01-01

    Polymer Filtration (PF) is an innovative, selective metal removal technology. Chelating, water-soluble polymers are used to selectively bind the desired metal ions and ultrafiltration is used to concentrate the polymer-metal complex producing a permeate with low levels of the targeted metal ion. When applied to the treatment of industrial metal-bearing aqueous process streams, the permeate water can often be reused within the process and the metal ions reclaimed. This technology is applicable to many types of industrial aqueous streams with widely varying chemistries. Application of PF to aqueous streams from nuclear materials processing and electroplating operations will be described

  18. Physicochemical impact studies of gamma rays on "aspirin" analgesics drug and its metal complexes in solid form: Synthesis, spectroscopic and biological assessment of Ca(II), Mg(II), Sr(II) and Ba(II) aspirinate complexes

    Science.gov (United States)

    Refat, Moamen S.; Sharshar, T.; Elsabawy, Khaled M.; Heiba, Zein K.

    2013-09-01

    Metal aspirinate complexes, M2(Asp)4, where M is Mg(II), Ca(II), Sr(II) or Ba(II) are formed by refluxed of aspirin (Asp) with divalent non-transition metal ions of group (II) and characterized by elemental analysis and spectroscopic measurements (infrared, electronic, 1H NMR, Raman, X-ray powder diffraction and scanning electron microscopy). Elemental analysis of the chelates suggests the stoichiometry is 1:2 (metal:ligand). Infrared spectra of the complexes agree with the coordination to the central metal atom through three donation sites of two oxygen atoms of bridge bidentate carboxylate group and oxygen atom of sbnd Cdbnd O of acetyl group. Infrared spectra coupled with the results of elemental analyzes suggested a distorted octahedral structure for the M(II) aspirinate complexes. Gamma irradiation was tested as a method for stabilization of aspirin as well as their complexes. The effect of gamma irradiation, with dose of 80 Gy, on the properties of aspirinate complexes was studied. The aspirinate chelates have been screened for their in vitro antibacterial activity against four bacteria, gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two strains of fungus (Aspergillus flavus and Candida albicans). The metal chelates were shown to possess more antibacterial activity than the free aspirin chelate.

  19. Layered Double Hydroxides as Effective Adsorbents for U(VI and Toxic Heavy Metals Removal from Aqueous Media

    Directory of Open Access Journals (Sweden)

    G. N. Pshinko

    2013-01-01

    Full Text Available Capacities of different synthesized Zn,Al-hydrotalcite-like adsorbents, including the initial carbonate [Zn4Al2(OH12]·CO3·8H2O and its forms intercalated with chelating agents (ethylenediaminetetraacetic acid (EDTA, diethylenetriaminepentaacetic acid (DTPA, and hexamethylenediaminetetraacetic acid (HMDTA and heat-treated form Zn4Al2O7, to adsorb uranium(VI and ions of toxic heavy metals have been compared. Metal sorption capacities of hydrotalcite-like adsorbents have been shown to correlate with the stability of their complexes with the mentioned chelating agents in a solution. The synthesized layered double hydroxides (LDHs containing chelating agents in the interlayer space are rather efficient for sorption purification of aqueous media free from U(VI irrespective of its forms of natural abundance (including water-soluble bi- and tricarbonate forms and from heavy metal ions. [Zn4Al2(OH12]·EDTA·nH2O is recommended for practical application as one of the most efficient and inexpensive synthetic adsorbents designed for recovery of both cationic and particularly important anionic forms of U(VI and other heavy metals from aqueous media. Carbonate forms of LDHs turned out to be most efficient for recovery of Cu(II from aqueous media with pH0≥7 owing to precipitation of Cu(II basic carbonates and Cu(II hydroxides. Chromate ions are efficiently adsorbed from water only by calcinated forms of LDHs.

  20. Antimicrobial Properties of Copper Nanoparticles and Amino Acid Chelated Copper Nanoparticles Produced by Using a Soya Extract

    Science.gov (United States)

    DeAlba-Montero, I.; Morales-Sánchez, Elpidio; Araujo-Martínez, Rene

    2017-01-01

    This paper reports a comparison of the antibacterial properties of copper-amino acids chelates and copper nanoparticles against Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis. These copper-amino acids chelates were synthesized by using a soybean aqueous extract and copper nanoparticles were produced using as a starting material the copper-amino acids chelates species. The antibacterial activity of the samples was evaluated by using the standard microdilution method (CLSI M100-S25 January 2015). In the antibacterial activity assays copper ions and copper-EDTA chelates were included as references, so that copper-amino acids chelates can be particularly suitable for acting as an antibacterial agent, so they are excellent candidates for specific applications. Additionally, to confirm the antimicrobial mechanism on bacterial cells, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) was carried out. A significant enhanced antimicrobial activity and a specific strain were found for copper chelates over E. faecalis. Its results would eventually lead to better utilization of copper-amino acids chelate for specific application where copper nanoparticles can be not used. PMID:28286459

  1. REVIEW ARTICLE:Future of Lead Chelation – Distribution and Treatment

    Directory of Open Access Journals (Sweden)

    Venkatesh Thuppil

    2012-01-01

    Full Text Available Lead is the major environmental toxin resulting in the ill health and deleterious effect on almost all organs in the human body in a slow and effective manner. The best treatment for lead poisoning is chelation therapy which is next only to prevention. The authors describe the disruption of homeostasis of the human body by lead in various tissues like blood, bones, liver, kidneys and brain; and the ability of lead to enter the cell using calcium channels and calcium receptors like Ca++ dependant K+ ion channels, transient receptor potential channels, T-tubules, calmodulin receptors, inositol trisphosphate receptors and ryanodine receptors. We report a few novel chelating agents like ionophores, decadentate ligands, picolinate ligands, octadentate ligand, allicin, thiamine, that show good potential for being used in chelation therapy. Future of leadpoisoning is a challenge to all and it needs to be meticulously studies to have an economic and health approach.

  2. Isotopic measurement of uranium using NP-type chelate resin beads

    International Nuclear Information System (INIS)

    Wu Lanbi; Chen Wenpo; Wang Shijun

    1994-08-01

    NP-type chelate resin beads is used as a carrier of samples in the isotopic measurements of uranium by mass spectrometry. The results show that its absorption efficiency for uranium can be greater than 50%. It is one order magnitude higher than that strong basic anion resin, however, the ionization efficiencies of both are almost the same. Therefore, the amount of uranium required for isotopic analysis can be reduced one order of magnitude. This method has been used for isotopic analysis of uranium in NP-type chelate resin beads contained 10 -9 ∼ 10 -7 g uranium. For standard sample UTB-500, the external precision of measurements are within +-0.2%, for natural uranium samples are within +- 0.5%. The application of NP-type chelate resin beads in the isotopic measurement of uranium is a new creative achievement. It has been used in the depletion test of uranium-atomic vapor laser isotope separation

  3. Radiopharmaceutical chelates and method of external imaging

    International Nuclear Information System (INIS)

    Loberg, M.D.; Callery, P.S.; Cooper, M.

    1977-01-01

    A chelate of technetium-99m, cobalt-57, gallium-67, gallium-68, indium-111 or indium-113m and a substituted iminodiacetic acid or an 8-hydroxyquinoline useful as a radiopharmaceutical external imaging agent. The invention also includes preparative methods therefor

  4. MRI marrow observations in thalassemia: the effects of the primary disease, transfusional therapy, and chelation

    International Nuclear Information System (INIS)

    Levin, T.L.; Sheth, S.S.; Ruzal-Shapiro, C.; Abramson, S.; Piomelli, S.; Berdon, W.E.

    1995-01-01

    The magnetic resonance bone marrow patterns in thalassemia were evaluated to determine changes produced by transfusion and chelation therapy. Thirteen patients had T1- and T2-weighted images of the spine, pelvis and femurs. Three received no therapy (age range 2.5-3 years). Three were ''hypertransfused'' (transfused to maintain a hemoglobin greater than 10 g/dl) and not chelated because of age (age range 6 months-8 years). Seven were ''hypertransfused'' and chelated (age range 12-35 years). Signal characteristics of marrow were compared with those of surrounding muscle and fat. Fatty marrow (isointense with subcutaneous fat) was compared with red marrow (hypointense to fat and slightly hyperintense to muscle). Marrow hypointense to muscle was identified as iron deposition within red marrow. The untreated group demonstrated signal consistent with red marrow throughout the central and peripheral skeleton. Hypertransfused but not chelated patients demonstrated marked iron deposition in the central and peripheral skeleton. Hypertransfused and chelated patients demonstrated iron deposition in the central skeleton and a mixed appearance of marrow in the peripheral skeleton. The MR appearance of marrow in thalassemia is a reflection of the patient's transfusion and chelation therapy. Iron deposition occurs despite chelation therapy in sites of active red marrow. As red marrow retreats centrally with age, so does the pattern of iron deposition. The long-term biological effects of this iron deposition are unknown. (orig.). With 8 figs., 1 tab

  5. Potentiometric study of Nd3+ chelates of substituted salicylhydroxamic acids

    International Nuclear Information System (INIS)

    Deshpande, R.G.; Jahagirdar, D.V.

    1976-01-01

    The interaction of Nd 3+ ion with salicylhydroxamic acid and 5-methyl, 5-chloro, 5-bromo, 5-nitro, 4-chloro, 4-bromo and 3-chloro salicylhydroxamic acids is investigated potentiometrically by Calvin-Bjerrum titration technique at 30 0 +- 0.1 0 and ionic strength μ=0.1 M(NaClO 4 ) in 50% v/v dioxane-water mixtures. Nd 3+ forms only 1:1 chelates with these ligands. The validity of the log K= apk + b relationship is examined for these chelates. (author)

  6. Self-diffusion coefficient of iron as affected by chelating agents using tracer technique

    International Nuclear Information System (INIS)

    Massoud, M.A.; Abd-El-Sabour, M.F.; Omar, M.A.

    1983-01-01

    The effect of Fe 2 (So 4 ) 3 , Fe-DTPA, and Fe-EDDHA on the self-diffusion coefficient of Fe in some soils of Egypt was studied. The effect of chelating compounds on the ratio between solid phase fraction of the labile Fe and its concentration in the soil solution (capacity factor) was also studied. The data reveals the following items of more interesting: 1) The use of chelating agents, i.e., DTPA and EDDHA increased the amount of Fe in soil solution, hence the capacity factor was decreased using these compounds. It seems that as the addition of Fe was in the chelated form in soil solution, the slight loss of 59Fe from solution when 59Fe - chelate was used could be attributed to the isotopic exchange with soil Fe. 2) It was found that the addition of either Fe-DTPA or Fe-EDDHA significantly increased the self-diffusion of Fe in soil as compared with Fe 2 (So 4 ) 3 . It was also noticed that the self-diffusion for Fe in the alluvial soil was greater than in the calcareous one due to the instance competition between Ca and Fe for the chelating ligands in the calcareous soil. It was also seen that soil texture affects Fe self-diffusion

  7. In vivo stability and inertness of various direct labelled and chelate-tagged protein

    International Nuclear Information System (INIS)

    Janoki, A.; Korosi, L.; Klivenyi, G.; Spett, B.

    1987-01-01

    There were looking for methods giving precise information about composition and activity distribution of protein components, both in the initial samples and serum samples after intravenous administration. It was tested the applicability of electroimmunoassay, polyacrilamide gel electrophoresis and high performance liquid chromatography for the assessment of in vivo stability and labelled proteins. The model compound was human serum albumin (HSA) labelled with 99m Tc and 125 I, respectively. Bifunctional chelate labelling was done with desferrioxamine, in this case protein was labelled with 67 Ga. Biodistribution of the labelled compounds and their elimination from the blood were studied in rabbits. Experience with various labelling proteins, especially with Tc-Sn-HSA system indicate that in vivo stability of this compounds are generally low. Following intravenous injection of proteins labelled with metal isotopes, due to dilution and to the presence of considerable amount of compatitive protein in the serum, part of the label is being detached from the carrier protein. Distribution of the detached metal is different from the original distribution of the protein. This problem arises also with radiopharmaceuticals based on monoclonal antibodies. (M.E.L.) [es

  8. Topical efficacy of dimercapto-chelating agents against lewisite-induced skin lesions in SKH-1 hairless mice

    Energy Technology Data Exchange (ETDEWEB)

    Mouret, Stéphane, E-mail: stephane.mouret@irba.fr [Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, Centre de Recherches du Service de Santé des Armées, 24 avenue Maquis du Grésivaudan, 38700 La Tronche (France); Wartelle, Julien; Emorine, Sandy; Bertoni, Marine; Nguon, Nina; Cléry-Barraud, Cécile [Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, Centre de Recherches du Service de Santé des Armées, 24 avenue Maquis du Grésivaudan, 38700 La Tronche (France); Dorandeu, Frédéric [Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, Centre de Recherches du Service de Santé des Armées, 24 avenue Maquis du Grésivaudan, 38700 La Tronche (France); Ecole du Val-de-Grâce, 1 place Alphonse Laveran, Paris (France); Boudry, Isabelle [Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, Centre de Recherches du Service de Santé des Armées, 24 avenue Maquis du Grésivaudan, 38700 La Tronche (France)

    2013-10-15

    Lewisite is a potent chemical warfare arsenical vesicant that can cause severe skin lesions. Today, lewisite exposure remains possible during demilitarization of old ammunitions and as a result of deliberate use. Although its cutaneous toxicity is not fully elucidated, a specific antidote exists, the British anti-lewisite (BAL, dimercaprol) but it is not without untoward effects. Analogs of BAL, less toxic, have been developed such as meso-2,3-dimercaptosuccinic acid (DMSA) and have been employed for the treatment of heavy metal poisoning. However, efficacy of DMSA against lewisite-induced skin lesions remains to be determined in comparison with BAL. We have thus evaluated in this study the therapeutic efficacy of BAL and DMSA in two administration modes against skin lesions induced by lewisite vapor on SKH-1 hairless mice. Our data demonstrate a strong protective efficacy of topical application of dimercapto-chelating agents in contrast to a subcutaneous administration 1 h after lewisite exposure, with attenuation of wound size, necrosis and impairment of skin barrier function. The histological evaluation also confirms the efficacy of topical application by showing that treatments were effective in reversing lewisite-induced neutrophil infiltration. This protective effect was associated with an epidermal hyperplasia. However, for all the parameters studied, BAL was more effective than DMSA in reducing lewisite-induced skin injury. Together, these findings support the use of a topical form of dimercaprol-chelating agent against lewisite-induced skin lesion within the first hour after exposure to increase the therapeutic management and that BAL, despite its side-effects, should not be abandoned. - Highlights: • Topically applied dimercapto-chelating agents reduce lewisite-induced skin damage. • One topical application of BAL or DMSA is sufficient to reverse lewisite effects. • Topical BAL is more effective than DMSA to counteract lewisite-induced skin damage.

  9. A multi-technique phytoremediation approach to purify metals contaminated soil from e-waste recycling site.

    Science.gov (United States)

    Luo, Jie; Cai, Limei; Qi, Shihua; Wu, Jian; Sophie Gu, Xiaowen

    2017-12-15

    Multiple techniques for soil decontamination were combined to enhance the phytoremediation efficiency of Eucalyptus globulese and alleviate the corresponding environmental risks. The approach constituted of chelating agent using, electrokinetic remediation, plant hormone foliar application and phytoremediation was designed to remediate multi-metal contaminated soils from a notorious e-waste recycling town. The decontamination ability of E. globulese increased from 1.35, 58.47 and 119.18 mg per plant for Cd, Pb and Cu in planting controls to 7.57, 198.68 and 174.34 mg per plant in individual EDTA treatments, respectively, but simultaneously, 0.9-11.5 times more metals leached from chelator treatments relative to controls. Low (2 V) and moderate (4 V) voltage electric fields provoked the growth of the species while high voltage (10 V) had an opposite effect and metal concentrations of the plants elevated with the increment of voltage. Volumes of the leachate decreased from 1224 to 134 mL with voltage increasing from 0 to 10 V due to electroosmosis and electrolysis. Comparing with individual phytoremediation, foliar cytokinin treatments produced 56% more biomass and intercepted 2.5 times more leachate attributed to the enhanced transpiration rate. The synergistic combination of the individuals resulted in the most biomass production and metal accumulation of the species under the stress condition relative to other methods. Time required for the multi-technique approach to decontaminate Cd, Pb and Cu from soil was 2.1-10.4 times less than individual chelator addition, electric field application or plant hormone utilization. It's especially important that nearly no leachate (60 mL in total) was collected from the multi-technique system. This approach is a suitable method to remediate metal polluted site considering its decontamination efficiency and associated environmental negligible risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Metal chaperones: a holistic approach to the treatment of AD

    Directory of Open Access Journals (Sweden)

    Paul Anthony Adlard

    2012-03-01

    Full Text Available As the burden of proof for the role of metal ion dysregulation in the pathogenesis of multiple CNS disorders grows, it has become important to more precisely identify and differentiate the biological effects of various pharmacological modulators of metal ion homeostasis. This is particularly evident in disorders such as Alzheimer’s disease, where the use of metal chaperones (that transport metals, as opposed to chelators (which exclude metals from biological interactions, may prove to be the first truly disease modifying approach for this condition. The purpose of this mini-review is to highlight the emerging notion that metal chaperones, such as PBT2 (Prana Biotechnology, modulate a variety of critical pathways affecting key aspects of the AD cascade to provide a more holistic approach to the treatment of this disease.

  11. Organically complexed copper, zinc, and chelating agents in the rivers of Western Puerto Rico

    International Nuclear Information System (INIS)

    Montgomery, J.R.; Echevarria, J.E.

    1975-01-01

    The method for determining soluble chelators gives their concentration in copper-equivalent chelating capacity units in fresh or slightly brackish (less than 3 percent salinity) water. The mean concentration of chelators in the Rio Guanajibo for December 1973 and January 1974 was 0.4 mg of copper per liter of water (N = 21, SD = 0.2) and for February 1974, 0.9 mg/liter (N = 8, SD = 0.4). The combined mean for the Rio Anasco and Culebrinas was 0.5 mg/liter (N = 7, SD = 0.4) in January and February 1974. The mean concentration of ionic copper was 0.5 μg/liter (N = 7, SD = 0.6) and of ionic zinc, 0.2 μg/liter (N = 8, SD = 0.1) in the Rio Guanajibo from November 1972 to February 1973. The concentration of organically bound copper was 0.3 μ/liter (N = 7, SD = 0.2) and that of organically bound zinc was 0.6 μg/liter (N = 8, SD = 0.6); this indicates that there was more than a sufficient quantity of chelator available in the river to complex all the soluble copper. The presence of a high ratio of Ca 2+ to Cu 2+ probably prevents the formation of larger concentrations of organically complexed copper. The mean concentration of chelating agents in the Guanajibo River seems to be directly related to the increased organic input from municipalities and a sugar mill. The concentration of chelators in tropical rivers appears to be higher than that found in Canadian lakes. The mean concentration for particulate organic carbon (POC) was 3653 μg atoms/liter (SD = 3653, N = 29). The dissolved reactive phosphate (DRP) ranged from a mean of 1.1 μg atom/liter. No significant correlation could be found between POC, DRP, and the concentration of chelators

  12. Mechanism and efficiency of cell death of type II photosensitizers: effect of zinc chelation.

    Science.gov (United States)

    Pavani, Christiane; Iamamoto, Yassuko; Baptista, Maurício S

    2012-01-01

    A series of meso-substituted tetra-cationic porphyrins, which have methyl and octyl substituents, was studied in order to understand the effect of zinc chelation and photosensitizer subcellular localization in the mechanism of cell death. Zinc chelation does not change the photophysical properties of the photosensitizers (all molecules studied are type II photosensitizers) but affects considerably the interaction of the porphyrins with membranes, reducing mitochondrial accumulation. The total amount of intracellular reactive species induced by treating cells with photosensitizer and light is similar for zinc-chelated and free-base porphyrins that have the same alkyl substituent. Zinc-chelated porphyrins, which are poorly accumulated in mitochondria, show higher efficiency of cell death with features of apoptosis (higher MTT response compared with trypan blue staining, specific acridine orange/ethidium bromide staining, loss of mitochondrial transmembrane potential, stronger cytochrome c release and larger sub-G1 cell population), whereas nonchelated porphyrins, which are considerably more concentrated in mitochondria, triggered mainly necrotic cell death. We hypothesized that zinc-chelation protects the photoinduced properties of the porphyrins in the mitochondrial environment. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

  13. The Metal Cation Chelating Capacity of Astaxanthin. Does This Have Any Influence on Antiradical Activity?

    Directory of Open Access Journals (Sweden)

    Ana Martínez

    2012-01-01

    Full Text Available In this Density Functional Theory study, it became apparent that astaxanthin (ASTA may form metal ion complexes with metal cations such as Ca+2, Cu+2, Pb+2, Zn+2, Cd+2 and Hg+2. The presence of metal cations induces changes in the maximum absorption bands which are red shifted in all cases. Therefore, in the case of compounds where metal ions are interacting with ASTA, they are redder in color. Moreover, the antiradical capacity of some ASTA-metal cationic complexes was studied by assessing their vertical ionization energy and vertical electron affinity, reaching the conclusion that metal complexes are slightly better electron donors and better electron acceptors than ASTA.

  14. Crystal structures reveal metal-binding plasticity at the metallo-β-lactamase active site of PqqB from Pseudomonas putida

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Xiongying; Latham, John A.; Klema, Valerie J.; Evans III, Robert L.; Li, Chao; Klinman, Judith P.; Wilmot, Carrie M. (UMM); (UCB)

    2017-08-19

    PqqB is an enzyme involved in the biosynthesis of pyrroloquinoline quinone and a distal member of the metallo-β-lactamase (MBL) superfamily. PqqB lacks two residues in the conserved signature motif HxHxDH that makes up the key metal-chelating elements that can bind up to two metal ions at the active site of MBLs and other members of its superfamily. Here, we report crystal structures of PqqB bound to Mn2+, Mg2+, Cu2+, and Zn2+. These structures demonstrate that PqqB can still bind metal ions at the canonical MBL active site. The fact that PqqB can adapt its side chains to chelate a wide spectrum of metal ions with different coordination features on a uniform main chain scaffold demonstrates its metal-binding plasticity. This plasticity may provide insights into the structural basis of promiscuous activities found in ensembles of metal complexes within this superfamily. Furthermore, PqqB belongs to a small subclass of MBLs that contain an additional CxCxxC motif that binds a structural Zn2+. Our data support a key role for this motif in dimerization.

  15. Identification of efficient chelating acids responsible for Cesium, Strontium and Barium complexes solubilization in mixed wastes

    International Nuclear Information System (INIS)

    Borai, E.H.

    2007-01-01

    The present paper is focused to characterize the available multi dentate ligand species and their metal ion complexes of cesium (Cs), strontium (Sr) and barium (Ba) formed with the parent chelators, complexing agents and its fragment products in mixed waste filtrate. The developed separation programs of different ligands by different mobile phases were based on the decrease of the effective charge of the anionic species in a differentiated way hence, the retention times on the stationary phases (AS-4A and AS-12A) are changed. Ion chromatographic (IC) analysis of the metal complexes showed that the carboxylic acids that are responsible for solubilizing Cs, Sr and Ba in the waste filtrate are NTA, Citrate and PDCA, respectively. Therefore, the predominant metal complexes in the filtrate at high ph are Cs (I)-NTA, Sr (IT)-Citrate and Ba (IT)-PDCA. Identification of the metal ion complexes responsible for solubilizing Cs, Sr and Ba was applied on the fresh and aged waste filtrates, to monitor their chemical behavior, which leads to increased control of the waste treatment process. Although, concentration measurements of both fresh and aged filtrates confirmed that the degradation process has occurred mainly due to a harsh chemical environment, the concentration of Cs(I), Sr(II) and Ba(II) increased slightly in the aged filterate compared with the fresh filtrate. This is due to the decomposition and/or degradation of their metal complexes and hence leads to free metal ion species in the filtrate. These observations indicate that the organic content of mixed waste filtrate is dynamic and need continuous analytical monitoring

  16. Enhancement of 67Ga tumor-to-blood ratios by chelating agent

    International Nuclear Information System (INIS)

    Saji, Hideo; Yokoyama, Akira; Hata, Naotaka; Misaki, Atsushi; Tanaka, Hisashi.

    1980-01-01

    Chelating agent, such as, CaEDTA, CaDTPA, D-penicillamine, DMSA, desferoxamine, NTA, cysteine ethyl ester, BAL, α-MPG, phthalein complexone, were tested as a possible contrast enhancing agent for tumor imaging with 67 Ga-citrate. The intravenous administration of a chelating agent to Ehrlich's tumor bearing mice, one hour after the injection of 67 Ga-citrate, accelerated the blood clearance with only a very slight change of activity in the target, increasing the tumor-to-blood ratio, and consequently achieving a better visualization. Among the tested chelating agents, D-penicillamine showed the highest target-to-nontarget ratio at a shorter time: a good tumor-to-blood ratio, performed after 24 hr with non-treated animals, was achieved in only 1-3 hr with post-treated animals. Thus, D-penicillamine hold a considerable promise as a contrast enhancing agent for future clinical use. (author)

  17. Self-diffusion coefficient of iron as affected by chelating agents using tracer technique

    Energy Technology Data Exchange (ETDEWEB)

    Massoud, M.A.; Abd-El-Sabour, M.F. (Agriculture Dept. for Soil and Water Research, Nuclear Research Centre, A.E.A., Cairo (Egypt)); Omar, M.A. (Ain Shams Univ., Cairo (Egypt). Faculty of Agriculture)

    1983-01-01

    The effect of Fe/sub 2/(So/sub 4/)/sub 3/, Fe-DTPA, and Fe-EDDHA on the self-diffusion coefficient of Fe in some soils of Egypt was studied. The effect of chelating compounds on the ratio between solid phase fraction of the labile Fe and its concentration in the soil solution (capacity factor) was also studied. The data reveals the following items of more interesting: 1) The use of chelating agents, i.e., DTPA and EDDHA increased the amount of Fe in soil solution, hence the capacity factor was decreased using these compounds. It seems that as the addition of Fe was in the chelated form in soil solution, the slight loss of 59Fe from solution when 59Fe - chelate was used could be attributed to the isotopic exchange with soil Fe. 2) It was found that the addition of either Fe-DTPA or Fe-EDDHA significantly increased the self-diffusion of Fe in soil as compared with Fe/sub 2/(So/sub 4/)/sub 3/. It was also noticed that the self-diffusion for Fe in the alluvial soil was greater than in the calcareous one due to the instance competition between Ca and Fe for the chelating ligands in the calcareous soil. It was also seen that soil texture affects Fe self-diffusion.

  18. Chelators for investigating zinc metalloneurochemistry

    OpenAIRE

    Radford, Robert John; Lippard, Stephen J.

    2013-01-01

    The physiology and pathology of mobile zinc signaling has become an important topic in metalloneurochemistry. To study the action of mobile zinc effectively, specialized tools are required that probe the temporal and positional changes of zinc ions within live tissue and cells. In the present article we describe the design and implementation of selective zinc chelators as antagonists to interrogate the function of mobile zinc, with an emphasis on the pools of vesicular zinc in the terminals o...

  19. Synthesis and Biological Activities on Metal Complexes of 2,5-Diamino-1,3,4-thiadiazole Derived from Semicarbazide Hydrochloride

    Directory of Open Access Journals (Sweden)

    Matthew A. Adebayo

    2011-07-01

    Full Text Available A bioactive ligand, 2,5-diamino-1,3,4-thiadiazole (L, derived from semicarbazide hydrochloride, and its metal complexes were prepared and characterized. The complexes were characterized using elemental, infra-red, ultraviolet/visible, magnetic moment, atomic absorption, thin layer chromatography and molar conductance measurements. The IR data revealed that the ligand (L behaved as a tridentate neutral ligand. It coordinated to the metal ion via sulphur and nitrogen of the amines. The molar conductance data reveal that the chelates are non-electrolytes. From the Ultraviolet/Visible spectra and magnetic moment data, the complexes were found to have octahedral geometrical structure. In vivo evaluation of the antimicrobial activities of the metal complexes and the ligands showed greater activity against some micro-organisms when compared to the parent compounds. The chelates do not show toxicity against the activities of enzymes from homogenates of liver, kidney and serum in experimental rats.

  20. Lead toxicosis of captive vultures: case description and responses to chelation therapy

    Science.gov (United States)

    2013-01-01

    Background Lead, a serious threat for raptors, can hamper the success of their conservation. This study reports on experience with accidental lead intoxication and responses to chelation therapy in captive Cinereous (Aegypius monachus) and Egyptian (Neophron percnopterus) Vultures. Results Soil contamination by lead-based paint sanded off the steel aviary resulted in poisoning of eight Cinereous and two Egyptian Vultures. A male Egyptian Vulture developed signs of apathy, polydipsia, polyuria, regurgitation, and stupor, and died on the next day. Liver, kidney and blood lead concentrations were 12.2, 8.16 and 2.66 μg/g, respectively. Laboratory analyses confirmed severe liver and kidney damage and anaemia. Blood Pb levels of Pb-exposed Cinereous Vultures were 1.571 ± 0.510 μg/g shortly after intoxication, decreased to 0.530 ± 0.165 μg/g without any therapy in a month and to 0.254 ± 0.097 μg/g one month after CaNa2EDTA administration. Eight months later, blood lead levels decreased to close to the background of the control group. Blood parameters of healthy Pb-non-exposed Cinereous Vultures were compared with those of the exposed group prior to and after chelation therapy. Iron levels in the lead-exposed pre-treatment birds significantly decreased after chelation. Haematocrit levels in Pb-exposed birds were significantly lower than those of the controls and improved one month after chelation. Creatine kinase was higher in pre-treatment birds than in the controls but normalised after therapy. Alkaline phosphatase increased after chelation. A marked increase in the level of lipid peroxidation measured as thiobarbituric acid reactive species was demonstrated in birds both prior to and after chelation. The ferric reducing antioxidant power was significantly lower in pre-treatment vultures and returned to normal following chelation therapy. Blood metallothionein levels in lead-exposed birds were higher than in controls. Reduced glutathione dropped after

  1. Lead toxicosis of captive vultures: case description and responses to chelation therapy.

    Science.gov (United States)

    Pikula, Jiri; Hajkova, Pavlina; Bandouchova, Hana; Bednarova, Ivana; Adam, Vojtech; Beklova, Miroslava; Kral, Jiri; Ondracek, Karel; Osickova, Jitka; Pohanka, Miroslav; Sedlackova, Jana; Skochova, Hana; Sobotka, Jakub; Treml, Frantisek; Kizek, Rene

    2013-01-16

    Lead, a serious threat for raptors, can hamper the success of their conservation. This study reports on experience with accidental lead intoxication and responses to chelation therapy in captive Cinereous (Aegypius monachus) and Egyptian (Neophron percnopterus) Vultures. Soil contamination by lead-based paint sanded off the steel aviary resulted in poisoning of eight Cinereous and two Egyptian Vultures. A male Egyptian Vulture developed signs of apathy, polydipsia, polyuria, regurgitation, and stupor, and died on the next day. Liver, kidney and blood lead concentrations were 12.2, 8.16 and 2.66 μg/g, respectively. Laboratory analyses confirmed severe liver and kidney damage and anaemia. Blood Pb levels of Pb-exposed Cinereous Vultures were 1.571 ± 0.510 μg/g shortly after intoxication, decreased to 0.530 ± 0.165 μg/g without any therapy in a month and to 0.254 ± 0.097 μg/g one month after CaNa(2)EDTA administration. Eight months later, blood lead levels decreased to close to the background of the control group. Blood parameters of healthy Pb-non-exposed Cinereous Vultures were compared with those of the exposed group prior to and after chelation therapy. Iron levels in the lead-exposed pre-treatment birds significantly decreased after chelation. Haematocrit levels in Pb-exposed birds were significantly lower than those of the controls and improved one month after chelation. Creatine kinase was higher in pre-treatment birds than in the controls but normalised after therapy. Alkaline phosphatase increased after chelation. A marked increase in the level of lipid peroxidation measured as thiobarbituric acid reactive species was demonstrated in birds both prior to and after chelation. The ferric reducing antioxidant power was significantly lower in pre-treatment vultures and returned to normal following chelation therapy. Blood metallothionein levels in lead-exposed birds were higher than in controls. Reduced glutathione dropped after CaNa(2)EDTA therapy, while

  2. Chelation studies involving decontamination of light lanthanides by polyaminopolycarboxylic

    International Nuclear Information System (INIS)

    Hassan, N.E.H.

    1985-01-01

    The present thesis constitutes chelation studies involving decontamination of light lanthanides, cobalt , and uranium with 2,2-bis-acryloyliminomethylene- acid (BAETA) using the spectrophotometric method. the work carried out aimed to clear up the effectiveness of BAETA as a decontaminating agent for radioactive nuclides from human body . the thesis includes a general introduction , outlines the aim of work and contains three main chapters . the results of the work are discussed at the end of the thesis. the first chapter deals with a comprehensive survey of the relevant literature. this includes the metabolism and toxicity of cerium, uranium, cobalt and Ln +3 elements, general methodologies of internal decontamination, choice and effectiveness of chelating agents

  3. Iron Chelators and Antioxidants Regenerate Neuritic Tree and Nigrostriatal Fibers of MPP+/MPTP-Lesioned Dopaminergic Neurons.

    Directory of Open Access Journals (Sweden)

    Pabla Aguirre

    Full Text Available Neuronal death in Parkinson's disease (PD is often preceded by axodendritic tree retraction and loss of neuronal functionality. The presence of non-functional but live neurons opens therapeutic possibilities to recover functionality before clinical symptoms develop. Considering that iron accumulation and oxidative damage are conditions commonly found in PD, we tested the possible neuritogenic effects of iron chelators and antioxidant agents. We used three commercial chelators: DFO, deferiprone and 2.2'-dypyridyl, and three 8-hydroxyquinoline-based iron chelators: M30, 7MH and 7DH, and we evaluated their effects in vitro using a mesencephalic cell culture treated with the Parkinsonian toxin MPP+ and in vivo using the MPTP mouse model. All chelators tested promoted the emergence of new tyrosine hydroxylase (TH-positive processes, increased axodendritic tree length and protected cells against lipoperoxidation. Chelator treatment resulted in the generation of processes containing the presynaptic marker synaptophysin. The antioxidants N-acetylcysteine and dymetylthiourea also enhanced axodendritic tree recovery in vitro, an indication that reducing oxidative tone fosters neuritogenesis in MPP+-damaged neurons. Oral administration to mice of the M30 chelator for 14 days after MPTP treatment resulted in increased TH- and GIRK2-positive nigra cells and nigrostriatal fibers. Our results support a role for oral iron chelators as good candidates for the early treatment of PD, at stages of the disease where there is axodendritic tree retraction without neuronal death.

  4. Understanding interaction of curcumin and metal ions on electrode surfaces using EDXRF

    Science.gov (United States)

    Joseph, Daisy; Kumar, K. Krishna; Narayanan, S. Sriman

    2018-04-01

    A chemically modified electrode was developed for determination of metal ions (Cd, Pb, Zn, Co, Hg). The modifier used for the study was Curcumin. Curcumin acts as a complexing agent at the surface of the electrode for preconcentration of metal ions from electrolyte to electrode surface and stripped back to electrolyte during analysis. EDXRF was used to analyze these electrodes and it was concluded that the PCR modified electrode favored effective chelation for lead and mercury.

  5. Evaluation of calcium di-sodium EDTA intramuscular injection using gamma scintigraphy against heavy metal poisoning

    International Nuclear Information System (INIS)

    Kumar, N.; Soni, S.; Mehra, L.; Mittal, G.; Nishad, D.K.; Bhatnagar, A.; Singh, T.; Ahmad, F.J.

    2010-01-01

    Full text: Heavy metals become toxic when they are not metabolized by the body and accumulate in soft tissues. These metals may enter the body through food, water, air or absorption through skin when an individual is exposed to areas with high heavy metal content such as agriculture, pharmaceutical manufacturing, paint and heavy metal industries or residential settings. Majority of population commonly get affected by heavy metal poisoning. Heavy metal poisoning is more likely to result through inhalation or ingestion route. Aim of the present study is to provide an easy, effective and controlled chelating therapy against heavy metal using Ca-disodium EDTA intramuscular injection. Ca-disodium-EDTA and Sesame oil were procured from Merck, India and Sigma Aldrich, USA respectively. Ca-Na 2 EDTA radiolabeling with 99m Tc-pertechnetate was standardized using stannous ions as reducing agent. The hypothesis of present work is to maintain effective concentration of chelating agent in blood for prolong time period. To test this hypothesis, we studied 1% Ca-Na 2 EDTA blood bioavailability after intramuscular depot administration in new zealand white rabbit. The optimized radiolabeled intramuscular formulation was evaluated for its dissolution and permeation studies in isotonic buffer solution were envisaged through radiometry. Sub-acute toxicity studies were performed after a single dose intramuscular administration of 1% Ca-Na 2 EDTA in Sprague Dawley rats. Radiolabeled Ca-disodium-EDTA (>95% labeled) was found to be fairly stable up to 24 h in physiological solution (Serum) as well as in normal saline with negligible degradation of 2.5% and 5.0% respectively, thereby indicating high stability of radiolabeled product. In-vitro data indicates that control release pattern (Cmax 24 hrs) with effective concentration up to seven days. 99m Tc-CaNa 2 EDTA retention at depot site was estimated up to 3 days by scintigraphy. Subacute toxicity studies done by histopathological

  6. Hydroxyurea could be a good clinically relevant iron chelator.

    Science.gov (United States)

    Italia, Khushnooma; Colah, Roshan; Ghosh, Kanjaksha

    2013-01-01

    Our previous study showed a reduction in serum ferritin of β-thalassemia patients on hydroxyurea therapy. Here we aimed to evaluate the efficacy of hydroxyurea alone and in combination with most widely used iron chelators like deferiprone and deferasirox for reducing iron from experimentally iron overloaded mice. 70 BALB/c mice received intraperitonial injections of iron-sucrose. The mice were then divided into 8 groups and were orally given hydroxyurea, deferiprone or deferasirox alone and their combinations for 4 months. CBC, serum-ferritin, TBARS, sTfr and hepcidin were evaluated before and after iron overload and subsequently after 4 months of drug therapy. All animals were then killed. Iron staining of the heart and liver tissue was done using Perl's Prussian Blue stain. Dry weight of iron in the heart and liver was determined by atomic absorption spectrometry. Increased serum-ferritin, TBARS, hepcidin and dry weight of iron in the liver and heart showed a significant reduction in groups treated with iron chelators with maximum reduction in the group treated with a combination of deferiprone, deferasirox and hydroxyurea. Thus hydroxyurea proves its role in reducing iron from iron overloaded mice. The iron chelating effect of these drugs can also be increased if given in combination.

  7. Hydroxyurea could be a good clinically relevant iron chelator.

    Directory of Open Access Journals (Sweden)

    Khushnooma Italia

    Full Text Available Our previous study showed a reduction in serum ferritin of β-thalassemia patients on hydroxyurea therapy. Here we aimed to evaluate the efficacy of hydroxyurea alone and in combination with most widely used iron chelators like deferiprone and deferasirox for reducing iron from experimentally iron overloaded mice. 70 BALB/c mice received intraperitonial injections of iron-sucrose. The mice were then divided into 8 groups and were orally given hydroxyurea, deferiprone or deferasirox alone and their combinations for 4 months. CBC, serum-ferritin, TBARS, sTfr and hepcidin were evaluated before and after iron overload and subsequently after 4 months of drug therapy. All animals were then killed. Iron staining of the heart and liver tissue was done using Perl's Prussian Blue stain. Dry weight of iron in the heart and liver was determined by atomic absorption spectrometry. Increased serum-ferritin, TBARS, hepcidin and dry weight of iron in the liver and heart showed a significant reduction in groups treated with iron chelators with maximum reduction in the group treated with a combination of deferiprone, deferasirox and hydroxyurea. Thus hydroxyurea proves its role in reducing iron from iron overloaded mice. The iron chelating effect of these drugs can also be increased if given in combination.

  8. Phytoremediation of heavy and transition metals aided by legume-rhizobia symbiosis

    DEFF Research Database (Denmark)

    Hao, X.; Taghavi, S.; Xie, P.

    2014-01-01

    Legumes are important for nitrogen cycling in the environment and agriculture due to the ability of nitrogen fixation by rhizobia. In this review, we introduce an important and potential role of legume-rhizobia symbiosis in aiding phytoremediation of some metal contaminated soils as various legumes...... have been found to be the dominant plant species in metal contaminated areas. Resistant rhizobia used for phytoremediation could act on metals directly by chelation, precipitation, transformation, biosorption and accumulation. Moreover, the plant growth promoting (PGP) traits of rhizobia including...... is not clear. Therefore, to obtain the maximum benefits from legumes assisted by rhizobia for phytoremediation of metals, it is critical to have a good understanding of interactions between PGP traits, the symbiotic plant-rhizobia relationship and metals....

  9. Complexation of trichlorosalicylic acids by alkaline and first row transition metals as a switch for their antibacterial activity

    KAUST Repository

    Kumar, Vijay

    2017-09-14

    3,5,6-trichlorosalicylic acid (TCSA) does not show a good antibacterial activity. In contrast, here metal complexes with TCSA have shown better antibacterial activity for selected bacterial strains with a good degree of selectivity. Amongst the eight synthesized essential metal complexes complexed with TCSA, Mn(II)-TCSA and Ni(II)-TCSA have been found to be more effective with MIC range 20-50 µg/L as compared to control (chloramphenicol). The activity of an individual complex against different microbes was not found to be identical, indicating the usage of an individual metal chelate against a targeted bacterial strain. Further, the protein (BSA) binding constant of TCSA and its metal complexes were determined and ordered as Ca(II)-TCSA > Cu(II)-TCSA > Mg(II)-TCSA >> Mn(II)-TCSA >> Zn(II)-TCSA >>> Ni(II)-TCSA >>> Co(II)-TCSA > Fe(II)-TCSA > TCSA. The present study has confirmed enhanced antibacterial activities and binding constants for metal chelates of TCSA as compared to free TCSA, which seems directly related with the antioxidant activities of these complexes. Further, bearing the ambiguity related to the structural characterization of the metal complexed with TCSA ligands, DFT calculations have been used as the tool to unravel the right environment around the metals, studying basically the relative stability of square planar and octahedral metal complexes with TCSA.

  10. Chelant extraction of heavy metals from contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Peters, R.W. [Energy Systems Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    1999-04-23

    The current state of the art regarding the use of chelating agents to extract heavy metal contaminants has been addressed. Results are presented for treatability studies conducted as worst-case and representative soils from Aberdeen Proving Ground's J-Field for extraction of copper (Cu), lead (Pb), and zinc (Zn). The particle size distribution characteristics of the soils determined from hydrometer tests are approximately 60% sand, 30% silt, and 10% clay. Sequential extractions were performed on the 'as-received' soils (worst case and representative) to determine the speciation of the metal forms. The technique speciates the heavy metal distribution into an easily extractable (exchangeable) form, carbonates, reducible oxides, organically-bound, and residual forms. The results indicated that most of the metals are in forms that are amenable to soil washing (i.e. exchangeable+carbonate+reducible oxides). The metals Cu, Pb, Zn, and Cr have greater than 70% of their distribution in forms amenable to soil washing techniques, while Cd, Mn, and Fe are somewhat less amenable to soil washing using chelant extraction. However, the concentrations of Cd and Mn are low in the contaminated soil. From the batch chelant extraction studies, ethylenediaminetetraacetic acid (EDTA), citric acid, and nitrilotriacetic acid (NTA) were all effective in removing copper, lead, and zinc from the J-Field soils. Due to NTA being a Class II carcinogen, it is not recommended for use in remediating contaminated soils. EDTA and citric acid appear to offer the greatest potential as chelating agents to use in soil washing the Aberdeen Proving Ground soils. The other chelating agents studied (gluconate, oxalate, Citranox, ammonium acetate, and phosphoric acid, along with pH-adjusted water) were generally ineffective in mobilizing the heavy metals from the soils. The chelant solution removes the heavy metals (Cd, Cu, Pb, Zn, Fe, Cr, As, and Hg) simultaneously. Using a multiple

  11. Chelant extraction of heavy metals from contaminated soils

    International Nuclear Information System (INIS)

    Peters, R.W.

    1999-01-01

    The current state of the art regarding the use of chelating agents to extract heavy metal contaminants has been addressed. Results are presented for treatability studies conducted as worst-case and representative soils from Aberdeen Proving Ground's J-Field for extraction of copper (Cu), lead (Pb), and zinc (Zn). The particle size distribution characteristics of the soils determined from hydrometer tests are approximately 60% sand, 30% silt, and 10% clay. Sequential extractions were performed on the 'as-received' soils (worst case and representative) to determine the speciation of the metal forms. The technique speciates the heavy metal distribution into an easily extractable (exchangeable) form, carbonates, reducible oxides, organically-bound, and residual forms. The results indicated that most of the metals are in forms that are amenable to soil washing (i.e. exchangeable+carbonate+reducible oxides). The metals Cu, Pb, Zn, and Cr have greater than 70% of their distribution in forms amenable to soil washing techniques, while Cd, Mn, and Fe are somewhat less amenable to soil washing using chelant extraction. However, the concentrations of Cd and Mn are low in the contaminated soil. From the batch chelant extraction studies, ethylenediaminetetraacetic acid (EDTA), citric acid, and nitrilotriacetic acid (NTA) were all effective in removing copper, lead, and zinc from the J-Field soils. Due to NTA being a Class II carcinogen, it is not recommended for use in remediating contaminated soils. EDTA and citric acid appear to offer the greatest potential as chelating agents to use in soil washing the Aberdeen Proving Ground soils. The other chelating agents studied (gluconate, oxalate, Citranox, ammonium acetate, and phosphoric acid, along with pH-adjusted water) were generally ineffective in mobilizing the heavy metals from the soils. The chelant solution removes the heavy metals (Cd, Cu, Pb, Zn, Fe, Cr, As, and Hg) simultaneously. Using a multiple-stage batch extraction

  12. Assessment of water-soluble thiourea-formaldehyde (WTF) resin for stabilization/solidification (S/S) of heavy metal contaminated soils.

    Science.gov (United States)

    Liu, She-Jiang; Jiang, Jia-Yu; Wang, Shen; Guo, Yu-Peng; Ding, Hui

    2018-03-15

    Stabilization/Solidification (S/S) can be regarded as necessary for remediation of heavy metal contaminated soil. There is, however, solid agent is not very convenient to use. Water-soluble thiourea-formaldehyde (WTF) is a novel chelating agent, which has more practical applications. The process of WTF resin for S/S process of heavy metal contaminated soils was studied. Laboratory-prepared slurries, made of field soils spiked with Cd 2+ and Cr 6+ were treated with WTF resin. The toxicity characteristic leaching procedure (TCLP) showed that with 2 wt% WTF, in the neutral condition of soil after treatment for 7 d, the leaching concentrations of Cd 2+ and Cr 6+ in contaminated soil were decreased by 80.3% and 92.6% respectively. Moreover, Tessier sequence extraction procedure showed WTF resin reduced the leaching concentration by transforming heavy metal from exchange form to organic form. The structure of WTF is obtained according to elemental analysis result and reaction mechanism. Through analysis of the infrared spectrogram of WTF and WTF heavy mental chelating precipitation, WTF can form stable chelate with heavy mental through coordination. The significant groups are hydroxyl, nitrogen and sulphur function groups in WTF mainly. Toxicology test revealed that the WTF resin is nontoxic to microorganism in the soils. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Removal of heavy elements from Contaminated Matrices using amidoxime chelating starch

    International Nuclear Information System (INIS)

    Shama, S.A.; Wally, S.A.; Aly, H.F.

    2012-01-01

    The synthesis of a amidoxime chelating starch was carried out by grafting of acrylonitrile onto starch using the mutual irradiation techniques at dose rate 2.5 kGy. Conversion of nitrile groups of the grafted copolymer into the amidoxime was carried out by treatment with hydroxylamine under alkaline solution. The amidoxime chelating starch was characterized by FT-IR spectra, TG, Particle size, Surface area, SEM, and Elemental analyses. The chelating behavior of the prepared resin was carried out by using uranium. The binding capacity of uranium ion by the amidoxime resin was carried out by the batch technique. The sorption capacity was high for uranium, 86.9 mg/g at ph 6.5. The kinetic exchange rate was fast. It was observed that the uranium uptake ratio reaches 50% at 10 min (t 1/2 ). The treatment process using amidoxime sorbent is efficient to remove uranium from the waste solution of the FMPP plant.

  14. CONTINUOUS CHELATION-EXTRACTION PROCESS FOR THE SEPARATION AND PURIFICATION OF METALS

    Science.gov (United States)

    Thomas, J.R.; Hicks, T.E.; Rubin, B.; Crandall, H.W.

    1959-12-01

    A continuous process is presented for separating metal values and groups of metal values from each other. A complex mixture. e.g., neutron-irradiated uranium, can be resolved into component parts. In the present process the values are dissolved in an acidic solution and adjusted to the proper oxidation state. Thenceforth the solution is contacted with an extractant phase comprising a fluorinated beta -diketone in an organic solvent under centain pH conditions whereupon plutonium and zirconium are extracted. Plutonium is extracted from the foregoing extract with reducing aqueous solutions or under specified acidic conditions and can be recovered from the aqueous solution. Zirconium is then removed with an oxalic acid aqueous phase. The uranium is recovered from the residual original solution using hexone and hexone-diketone extractants leaving residual fission products in the original solution. The uranium is extracted from the hexone solution with dilute nitric acid. Improved separations and purifications are achieved using recycled scrub solutions and the "self-salting" effect of uranyl ions.

  15. f-Element Ion Chelation in Highly Basic Media

    International Nuclear Information System (INIS)

    Paine, Robert T.

    1999-01-01

    High-level radioactive waste (HLW) generated in the DOE complex is stored in tanks at several sites, but predominantly it is found at the Hanford reservation. Much of the material has been exposed to high pHs, consequently the waste exists in a complex, poorly understood mixture of solids, gels and solutions. The final waste remediation plan may involve chemical separation of fractions and a suitable, well developed molecular chemistry basis for performing these separations is not available. Indeed, the fundamental chemical behavior of most radioactive nuclides in basic media is not known. The goal of this project is to undertake fundamental studies of the coordination chemistry of f-element species in basic aqueous solutions containing common waste treatment ions (e.g., NO3 -, CO3 2-, organic carboxylates, and EDTA), as well as new waste scrubbing chelators produced in this study. The experimental agenda includes: 1. Studies of the speciation of Sr and Ln ions in basic solutions wit h and without common counterions; 2. Preparations of new multifunctional ligands that may act as strong, ion-specific chelators for Sr and/or Ln ions in basic media; and 3. Studies of the coordination and dissolution behavior of oxide-hydroxide species, as well as in insoluble sols, gels, and precipitates in combination with new chelating ligands. It is anticipated that this coordination chemistry will facilitate the design of advanced separation schemes required for handling the complex waste matrices found at the Hanford HLW facility

  16. Structure investigation, spectral, thermal, X-ray and mass characterization of piroxicam and its metal complexes

    Science.gov (United States)

    Zayed, M. A.; Nour El-Dien, F. A.; Mohamed, Gehad G.; El-Gamel, Nadia E. A.

    2004-10-01

    [M(H 2L) 2](A) 2. yH 2O (where H 2L: neutral piroxicam (Pir), A: Cl - in case of Ni(II) or acetate anion in case of Cu(II) and Zn(II) ions and y=0-2.5) and [M(H 2L) 3](A) z. yH 2O (A: SO 42- in case of Fe(II) ion ( z=1) or Cl - in case of Fe(III) ( z=3) and Co(II) ions ( z=2) and y=1-4) chelates are prepared and characterized using elemental analyses, IR, magnetic and electronic reflectance measurements, mass spectra and thermal analyses. IR spectra reveal that Pir behaves a neutral bidentate ligand coordinated to the metal ions through the pyridyl-N and carbonyl-O of the amide moiety. The reflectance and magnetic moment measurements reveal that these chelates have tetrahedral, square planar and octahedral geometrical structures. Mass spectra and thermal analyses are also used to confirm the proposed formulae and the possible fragments resulted from fragmentation of Pir and its chelates. The thermal behaviour of the chelates (TGA and DTA) are discussed in detail and the thermal stability of the anhydrous chelates follow the order Ni(II)≅Cu(II)chelates. The water molecules are removed in the first step while the Pir molecule is removed in the second and subsequent steps. X-ray powder diffraction was also used as a confirmatory tool to elucidate the crystallinity of the chelates.

  17. Synthesis and antimalarial activity of metal complexes of cross-bridged tetraazamacrocyclic ligands.

    Science.gov (United States)

    Hubin, Timothy J; Amoyaw, Prince N-A; Roewe, Kimberly D; Simpson, Natalie C; Maples, Randall D; Carder Freeman, TaRynn N; Cain, Amy N; Le, Justin G; Archibald, Stephen J; Khan, Shabana I; Tekwani, Babu L; Khan, M O Faruk

    2014-07-01

    Using transition metals such as manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and zinc(II), several new metal complexes of cross-bridged tetraazamacrocyclic chelators namely, cyclen- and cyclam-analogs with benzyl groups, were synthesized and screened for in vitro antimalarial activity against chloroquine-resistant (W2) and chloroquine-sensitive (D6) strains of Plasmodium falciparum. The metal-free chelators tested showed little or no antimalarial activity. All the metal complexes of the dibenzyl cross-bridged cyclam ligand exhibited potent antimalarial activity. The Mn(2+) complex of this ligand was the most potent with IC50s of 0.127 and 0.157μM against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) P. falciparum strains, respectively. In general, the dibenzyl hydrophobic ligands showed better anti-malarial activity compared to the activity of monobenzyl ligands, potentially because of their higher lipophilicity and thus better cell penetration ability. The higher antimalarial activity displayed by the manganese complex for the cyclam ligand in comparison to that of the cyclen, correlates with the larger pocket of cyclam compared to that of cyclen which produces a more stable complex with the Mn(2+). Few of the Cu(2+) and Fe(2+) complexes also showed improvement in activity but Ni(2+), Co(2+) and Zn(2+) complexes did not show any improvement in activity upon the metal-free ligands for anti-malarial development. Published by Elsevier Ltd.

  18. Effects of lead and chelators on growth, photosynthetic activity and Pb uptake in Sesbania drummondii grown in soil

    International Nuclear Information System (INIS)

    Ruley, Adam T.; Sharma, Nilesh C.; Sahi, Shivendra V.; Singh, Shree R.; Sajwan, Kenneth S.

    2006-01-01

    Effects of lead (Pb) and chelators, such as EDTA, HEDTA, DTPA, NTA and citric acid, were studied to evaluate the growth potential of Sesbania drummondii in soils contaminated with high concentrations of Pb. S. drummondii seedlings were grown in soil containing 7.5 g Pb(NO 3 ) 2 and 0-10 mmol chelators/kg soil for a period of 2 and 4 weeks and assessed for growth profile (length of root and shoot), chlorophyll a fluorescence kinetics (F v /F m and F v /F o ) and Pb accumulations in root and shoot. Growth of plants in the presence of Pb + chelators was significantly higher (P v /F m and F v /F o values of treated seedlings remained unaffected, indicating normal photosynthetic efficiency and strength of plants in the presence of chelators. On application of chelators, while root uptake of Pb increased four-five folds, shoot accumulations increased up to 40-folds as compared to controls (Pb only) depending on the type of chelator used. Shoot accumulations of Pb varied from 0.1 to 0.42% (dry weight) depending on the concentration of chelators used. - Sesbania drummondii tolerates and accumulates high concentrations of Pb

  19. Preparation of Amidoxime Polyacrylonitrile Chelating Nanofibers and Their Application for Adsorption of Metal Ions

    Directory of Open Access Journals (Sweden)

    You-Lo Hsieh

    2013-03-01

    Full Text Available Polyacrylonitrile (PAN nanofibers were prepared by electrospinning and they were modified with hydroxylamine to synthesize amidoxime polyacrylonitrile (AOPAN chelating nanofibers, which were applied to adsorb copper and iron ions. The conversion of the nitrile group in PAN was calculated by the gravimetric method. The structure and surface morphology of the AOPAN nanofiber were characterized by a Fourier transform infrared spectrometer (FT-IR and a scanning electron microscope (SEM, respectively. The adsorption abilities of Cu2+ and Fe3+ ions onto the AOPAN nanofiber mats were evaluated. FT-IR spectra showed nitrile groups in the PAN were partly converted into amidoxime groups. SEM examination demonstrated that there were no serious cracks or sign of degradation on the surface of the PAN nanofibers after chemical modification. The adsorption capacities of both copper and iron ions onto the AOPAN nanofiber mats were higher than those into the raw PAN nanofiber mats. The adsorption data of Cu2+ and Fe3+ ions fitted particularly well with the Langmuir isotherm. The maximal adsorption capacities of Cu2+ and Fe3+ ions were 215.18 and 221.37 mg/g, respectively.

  20. Column liquid chromatography applied to concentrating, separating, and determining platinum metals

    International Nuclear Information System (INIS)

    Alimarin, I.P.; Basova, E.M.; Bol'shova, T.A.; Ivanov, V.M.

    1986-01-01

    The present survey deals with high-performance liquid chromatography (HPLC) in relation to the chromatographic behavior of the platinum metals, including separation and determination. The data shows that HPLC is the most promising and effective method of separating metals, including platinum ones. The method provides efficient separation of microgram amoounts of mixtures with a resolving power 3-20 times that of thin-layer chromatography. It is shown that the most promising line of advance in HPLC for inorganic systems lies in the separation and determination of metals as chelates by absorption or ion-pair chromatography. Examples of using HPLC for determining noble metals in particular cases indicate that the metrological characteristics are favorable