WorldWideScience

Sample records for metal 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. Clawing Back: Broadening the Notion of Metal Chelators in Medicine

    OpenAIRE

    Franz, Katherine J.

    2013-01-01

    The traditional notion of chelation therapy is the administration of a chemical agent to remove metals from the body. But formation of a metal-chelate can have biological ramifications that are much broader than metal elimination. Exploring these other possibilities could lead to pharmacological interventions that alter the concentration, distribution, or reactivity of metals in targeted ways for therapeutic benefit. This review highlights recent examples that showcase four general strategies...

  4. Metal regeneration of iron chelates in nitric oxide scrubbing

    Science.gov (United States)

    Chang, Shih-Ger; Littlejohn, David; Shi, Yao

    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.degree. and 90.degree. 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.

  5. 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)

  6. Quantitative measurement of metal chelation by fourier transform infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    Monika E. Miller

    2015-12-01

    Full Text Available Nutritionally important minerals are more readily absorbed by living systems when complexed with organic acids, resulting in higher consumer demand and premium prices for these products. These chelated metals are produced by reaction of metal oxides and acids in aqueous solution. However, unreacted dry blends are sometimes misrepresented as metal chelates, when in reality they are only simple mixtures of the reactants typically used to synthesize them. This practice has increased interest in developing analytical methods that are capable of measuring the extent of metal chelation for quality control and regulatory compliance. We describe a novel method to rapidly measure the percent chelation of citric and malic acids with calcium, magnesium, and zinc. Utilization of attenuated total reflectance (FTIR-ATR provides for the direct, rapid measurement of solid samples. The inclusion of an internal standard allows independent determination of either free or chelated acids from integrated areas in a single spectrum.

  7. Supercritical Fluid Extraction of Metal Chelate: A Review.

    Science.gov (United States)

    Ding, Xin; Liu, Qinli; Hou, Xiongpo; Fang, Tao

    2017-03-04

    Supercritical fluid extraction (SFE), as a new green extraction technology, has been used in extracting various metal species. The solubilities of chelating agents and corresponding metal chelates are the key factors which influence the efficiency of SFE. Other main properties of them such as stability and selectivity are also reviewed. The extraction mechanisms of mainly used chelating agents are explained by typical examples in this paper. This is the important aspect of SFE of metal ions. Moreover, the extraction efficiencies of metal species also depend on other factors such as temperature, pressure, extraction time and matrix effect. The two main complexation methods namely in-situ and on-line chelating SFE are described in detail. As an efficient chelating agent, tributyl phosphate-nitric acid (TBP-HNO 3 ) complex attracts much attention. The SFE of metal ions, lanthanides and actinides as well as organometallic compounds are also summarized. With the proper selection of ligands, high efficient extraction of metal species can be obtained. As an efficient sample analysis method, supercritical fluid chromatography (SFC) is introduced in this paper. Recently, the extraction method combining ionic liquids (ILs) with supercritical fluid has been becoming a novel technology for treating metal ions. The kinetics related to SFE of metal species is discussed with some specific examples.

  8. Metal chelate process to remove pollutants from fluids

    Science.gov (United States)

    Chang, Shih-Ger T.

    1994-01-01

    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.

  9. Metal chelates of N-alkylacetoacetanilides

    Energy Technology Data Exchange (ETDEWEB)

    Thankarajan, N.; Sreeman, P. (Calicut Univ. (India). Dept. of Chemistry)

    1981-04-01

    Beryllium(II), copper(II) and iron(III) chelates of N-methylacetoacetanilide, and beryllium(II), copper(II), chromium(III), Iron(III) and dioxouranium(VI) chelates of N-methyl- and N-ethyl-acetoacetanilides have been prepared and characterised on the basis of their analytical, spectral (UV, IR, PMR) and other physicochemical data. Polarographic studies reveal that the copper(II) complexes of the above ligands are stabler than that of acetoacetanilide. Pentagonal-bipyramidal structure for the uranium complex, and square-pyramidal structure for 1:1 adducts of the copper complexes with pyridine, have been suggested on the basis of the spectral data.

  10. 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)

  11. Laccase Immobilization by Chelated Metal Ion Coordination Chemistry

    Directory of Open Access Journals (Sweden)

    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.

  12. Extraction of metals using supercritical fluid and chelate forming ligand

    International Nuclear Information System (INIS)

    Wai, C.M.; Laintz, K.E.

    1998-01-01

    A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated β-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated β-diketone and a trialkyl phosphate, or a fluorinated β-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated β-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process. 7 figs

  13. Anti-Oxidative, Metal Chelating and Radical Scavenging Effects of ...

    African Journals Online (AJOL)

    Purpose: To evaluate protein hydrolysates and membrane ultrafiltration fractions of blue-spotted stingray for metal chelating and radical scavenging activities, as well as protection against oxidative protein damage. Methods: Stingray protein isolates were hydrolysed with alcalase, papain and trypsin for 3 h. Alcalase.

  14. 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 .'

  15. Metal chelates of azo-pyridazine dyes Chelating tendencies of benzoylacetone-monohydrazone-3-hydrazino-4-benzyl-6-phenylpyridazine (bahp).

    Science.gov (United States)

    Ramadan, A A; Seada, M H; Rizkalla, E N

    1983-04-01

    The synthesis, acid-base equilibria and metal-ion chelating tendencies of BAHP are reported. From potentiometric equilibrium measurements of hydrogen-ion concentration at 30 degrees and ionic strength 0.10M (KNO(3)), in 75% dioxan-water medium, the values of the stability constants of some BAHP complexes with transition, non-transition and lanthanide ions have been evaluated. Probable structures of the metal chelates are inferred from the electronic absorption spectra and infrared examination of the solid copper complex. The use of BAHP as an analytical reagent for the spectrophotometric determination of copper, nickel and cobalt ions is discussed.

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

    DEFF Research Database (Denmark)

    Andersen, Ole; Aaseth, Jan

    2016-01-01

    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...... 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...... 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...

  17. 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.

  18. mer and fac isomerism in tris chelate diimine metal complexes.

    Science.gov (United States)

    Dabb, Serin L; Fletcher, Nicholas C

    2015-03-14

    In this perspective, we highlight the issue of meridional (mer) and facial (fac) orientation of asymmetrical diimines in tris-chelate transition metal complexes. Diimine ligands have long been the workhorse of coordination chemistry, and whilst there are now good strategies to isolate materials where the inherent metal centered chirality is under almost complete control, and systematic methodologies to isolate heteroleptic complexes, the conceptually simple geometrical isomerism has not been widely investigated. In systems where the two donor atoms are significantly different in terms of the σ-donor and π-accepting ability, the fac isomer is likely to be the thermodynamic product. For the diimine complexes with two trigonal planar nitrogen atoms there is much more subtlety to the system, and external factors such as the solvent, lattice packing and the various steric considerations play a delicate role in determining the observed and isolable product. In this article we discuss the possibilities to control the isomeric ratio in labile systems, consider the opportunities to separate inert complexes and discuss the observed differences in their spectroscopic properties. Finally we report on the ligand orientation in supramolecular systems where facial coordination leads to simple regular structures such as helicates and tetrahedra, but the ability of the ligand system to adopt a mer orientation enables self-assembled structures of considerable beauty and complexity.

  19. 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.

  20. Analysis of Supercritical-Extracted Chelated Metal Ions From Mixed Organic-Inorganic Samples

    Science.gov (United States)

    Sinha, Mahadeva P. (Inventor)

    1996-01-01

    Organic and inorganic contaminants of an environmental sample are analyzed by the same GC-MS instrument by adding an oxidizing agent to the sample to oxidize metal or metal compounds to form metal ions. The metal ions are converted to chelate complexes and the chelate complexes are extracted into a supercritical fluid such as CO2. The metal chelate extract after flowing through a restrictor tube is directly injected into the ionization chamber of a mass spectrometer, preferably containing a refractory metal filament such as rhenium to fragment the complex to release metal ions which are detected. This provides a fast, economical method for the analysis of metal contaminants in a sample and can be automated. An organic extract of the sample in conventional or supercritical fluid solvents can be detected in the same mass spectrometer, preferably after separation in a supercritical fluid chromatograph.

  1. 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.

  2. (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).

  3. [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).

  4. A Speciation Study on the Perturbing Effects of Iron Chelators on the Homeostasis of Essential Metal Ions.

    Science.gov (United States)

    Crisponi, Guido; Nurchi, Valeria Marina; Crespo-Alonso, Miriam; Sanna, Gavino; Zoroddu, Maria Antonietta; Alberti, Giancarla; Biesuz, Raffaela

    2015-01-01

    A number of reports have appeared in literature calling attention to the depletion of essential metal ions during chelation therapy on β-thalassaemia patients. We present a speciation study to determine how the iron chelators used in therapy interfere with the homeostatic equilibria of essential metal ions. This work includes a thorough analysis of the pharmacokinetic properties of the chelating agents currently in clinical use, of the amounts of iron, copper and zinc available in plasma for chelation, and of all the implied complex formation constants. The results of the study show that a significant amount of essential metal ions is complexed whenever the chelating agent concentration exceeds the amount necessary to coordinate all disposable iron--a frequently occurring situation during chelation therapy. On the contrary, copper and zinc do not interfere with iron chelation, except for a possible influence of copper on iron speciation during deferiprone treatment.

  5. 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

  6. 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.

  7. Influence of chelation ratio of metal alkoxides on aging of PZT 53/47 ...

    Indian Academy of Sciences (India)

    Administrator

    GDL-Ameca km 45.5, CP 46600 Ameca, Jalisco, Mexico. MS received 21 September 2013. Abstract. The high reactivity of metal alkoxides, common starting reagents in sol–gel-based synthesis routes, generally demands the use of chelating agents in order to avoid fast hydrolysis and also to allow an easier manipulation of ...

  8. 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.

  9. 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

  10. Regulation of copper and iron homeostasis by metal chelators: a possible chemotherapy for Alzheimer's disease.

    Science.gov (United States)

    Robert, Anne; Liu, Yan; Nguyen, Michel; Meunier, Bernard

    2015-05-19

    With the increase of life expectancy of humans in more than two-thirds of the countries in the World, aging diseases are becoming the frontline health problems. Alzheimer's disease (AD) is now one of the major challenges in drug discovery, since, with the exception of memantine in 2003, all clinical trials with drug candidates failed over the past decade. If we consider that the loss of neurons is due to a high level of oxidative stress produced by nonregulated redox active metal ions like copper linked to amyloids of different sizes, regulation of metal homeostasis is a key target. The difficulty for large copper-carrier proteins to directly extract copper ions from metalated amyloids might be considered as being at the origin of the rupture of the copper homeostasis regulation in AD brains. So, there is an urgent need for new specific metal chelators that should be able to regulate the homeostasis of metal ions, specially copper and iron, in AD brains. As a consequence of that concept, chelators promoting metal excretion from brain are not desired. One should favor ligands able to extract copper ions from sinks (amyloids being the major one) and to transfer these redox-active metal ions to copper-carrier proteins or copper-containing enzymes. Obviously, the affinity of these chelators for the metal ion should not be a sufficient criterion, but the metal specificity and the ability of the chelators to release the metal under specific biological conditions should be considered. Such an approach is still largely unexplored. The requirements for the chelators are very high (ability to cross the brain-blood barrier, lack of toxicity, etc.), few chemical series were proposed, and, among them, biochemical or biological data are scarce. As a matter of fact, the bioinorganic pharmacology of AD represents less than 1% of all articles dedicated to AD drug research. The major part of these articles deals with an old and rather toxic drug, clioquinol and related analogs, that

  11. In vitro evaluation of metal chelators as potential metallo- β -lactamase inhibitors.

    Science.gov (United States)

    Azumah, R; Dutta, J; Somboro, A M; Ramtahal, M; Chonco, L; Parboosing, R; Bester, L A; Kruger, H G; Naicker, T; Essack, S Y; Govender, T

    2016-04-01

    This study aimed at investigating the use of metal chelators as potential metallo-β-lactamase inhibitors (MBL). The minimum inhibitory concentration (MIC) of meropenem was ascertained alone and in combination with various concentrations of macrocyclic (1,4,7- triazacyclononane-1-glutaric acid-4,7-diacetic acid = NODAGA) peptide derivatives and acyclic (N,N,N',N'-Tetrakis(2-pyridylmethyl)ethylenediamine = TPEN and di-(2-picolyl)amine = DPA) metal chelators using the broth microdilution method. MICs of meropenem against carbapenem-resistant enterobacteriaceae (CRE) producing MBLs were decreased to concentrations as low as 0·06 mg l(-1) in the presence of some metal chelators. TPEN at 4 and 8 mg l(-1) showed the best activity by decreasing meropenem MICs to 0·5 and 0·06 mg l(-1) , respectively, for some New Delhi Metallo-beta-lactamase (NDM) and Verona integron-encoded metallo-β-lactamase (VIM) -producing enterobacteriaceae. DPA at 8 and 16 mg l(-1) was also able to decrease meropenem MICs to 1 and 0·125 mg l(-1) , respectively, for these CREs. NODAGA peptide derivatives showed the least inhibition as 32 mg l(-1) was required for meropenem MICs to be decreased to 0·06 mg l(-1) against an NDM-1 producing isolate. The various metal chelators, TPEN, DPA and NODAGA peptide derivatives were able to inhibit the MBLs in decreasing order of activity, rendering CREs susceptible to meropenem. In the absence of new antibiotics, this study evaluated metal chelators as potential MBL inhibitors. © 2016 The Society for Applied Microbiology.

  12. Uranyl binary and ternary chelates of tenoxicam. Synthesis, spectroscopic and thermal characterization of ternary chelates of tenoxicam and alanine with transition metals

    Science.gov (United States)

    El-Gamel, Nadia E. A.

    2007-11-01

    Ternary Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and UO 2(II) chelates with tenoxicam (Ten) drug (H 2L 1) and dl-alanine (Ala) (HL 2) and also the binary UO 2(II) chelate with Ten were studied. The structures of the chelates were elucidated using elemental, molar conductance, magnetic moment, IR, diffused reflectance and thermal analyses. UO 2(II) binary chelate was isolated in 1:2 ratio with the formula [UO 2(H 2L) 2](NO 3) 2. The ternary chelates were isolated in 1:1:1 (M:H 2L 1:L 2) ratios and have the general formulae [M(H 2L 1)(L 2)(Cl) n(H 2O) m]· yH 2O (M = Fe(III) ( n = 2, m = 0, y = 2), Co(II) ( n = 1, m = 1, y = 2) and Ni(II) ( n = 1, m = 1, y = 3)); [M(H 2L 1)(L 2)](X) z· yH 2O (M = Cu(II) (X = AcO, z = 1, y = 0), Zn(II) (X = AcO, z = 1, y = 3) and UO 2(II) (X = NO 3, z = 1, y = 2)). IR spectra reveal that Ten behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl-O groups, while Ala behaves as a uninegatively bidentate ligand coordinated to the metal ions via the deprotonated carboxylate-O and amino-N. The magnetic and reflectance spectral data confirm that all the chelates have octahedral geometry except Cu(II) and Zn(II) chelates have tetrahedral structures. Thermal decomposition of the chelates was discussed in relation to structure and different thermodynamic parameters of the decomposition stages were evaluated.

  13. 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.

  14. The phospholipid vesicles coating on metal chelated inorganic surfaces

    International Nuclear Information System (INIS)

    Chang, Jeong Ho; Cho, Min Ae; Son, Hong Ha; Lee, Cheon Koo; Kim, Kyung Ja

    2007-01-01

    This work showed the formation of phospholipid vesicle coating on inorganic sericite surface with characterization by combining electron microscopy of FE-SEM, TEM, AFM, and qualitatively evaluated the coated phospholipid vesicle by XPS as a function of etching time. The possibility of phospholipid vesicle mobility on the surface was restrained by the chelation effect of magnesium cation. The stabilization properties of phospholipid vesicles on sericite surface were demonstrated by the various concentration of magnesium cation. The presence of magnesium was found to have a much more pronounced influence on the lipid deposition process. The Mg cation plays an important role for attaching the phospholipids with optimum concentration of 7 mM. Totally, the phospholipid vesicles coating on inorganic powder could be useful for bio-related fields such as cosmetics and drug delivery system as the key functional compounds. We hope this basic result lead to a general and simple approach to prepare a wide a range of controlled releasing materials including an encapsulation with cosmetics or drugs

  15. 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.

  16. Actinide chelation: biodistribution and in vivo complex stability of the targeted metal ions.

    Science.gov (United States)

    Kullgren, Birgitta; Jarvis, Erin E; An, Dahlia D; Abergel, Rebecca J

    2013-01-01

    Because of the continuing use of nuclear fuel sources and heightened threats of nuclear weapon use, the amount of produced and released radionuclides is increasing daily, as is the risk of larger human exposure to fission product actinides. A rodent model was used to follow the in vivo distribution of representative actinides, administered as free metal ions or complexed with chelating agents including diethylenetriamine pentaacetic acid (DTPA) and the hydroxypyridinonate ligands 3,4,3-LI(1,2-HOPO) and 5-LIO(Me-3,2-HOPO). Different metabolic pathways for the different metal ions were evidenced, resulting in intricate ligand- and metal-dependent decorporation mechanisms. While the three studied chelators are known for their unrivaled actinide decorporation efficiency, the corresponding metal complexes may undergo in vivo decomposition and release metal ions in various biological pools. This study sets the basis to further explore the metabolism and in vivo coordination properties of internalized actinides for the future development of viable therapeutic chelating agents.

  17. 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

  18. Solid-phase materials for chelating metal ions and methods of making and using same

    Science.gov (United States)

    Harrup, Mason K.; Wey, John E.; Peterson, Eric S.

    2003-06-10

    A solid material for recovering metal ions from aqueous streams, and methods of making and using the solid material, are disclosed. The solid material is made by covalently bonding a chelating agent to a silica-based solid, or in-situ condensing ceramic precursors along with the chelating agent to accomplish the covalent bonding. The chelating agent preferably comprises a oxime type chelating head, preferably a salicylaldoxime-type molecule, with an organic tail covalently bonded to the head. The hydrocarbon tail includes a carbon-carbon double bond, which is instrumental in the step of covalently bonding the tail to the silica-based solid or the in-situ condensation. The invented solid material may be contacted directly with aqueous streams containing metal ions, and is selective to ions such as copper (II) even in the presence of such ions as iron (III) and other materials that are present in earthen materials. The solid material with high selectivity to copper may be used to recover copper from mining and plating industry streams, to replace the costly and toxic solvent extraction steps of conventional copper processing.

  19. 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

  20. 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 ...

  1. Chromatography of metal ions with a triazine chelating resin

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. 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

  3. Dinuclear metal complexes derived from a bis-chelating heterocyclic ...

    African Journals Online (AJOL)

    The analytical data indicate that the metal to ligand ratio is 2:1 in all the complexes. The coordination of triethylamine, water and chloride ion are observed in the Co(II), Zn(II) and Ni(II) complexes. The absence of ionizable or coordinated chloride in Cu(II) complex is a notable feature. Octahedral geometry for Co(II), Zn(II) and ...

  4. FTIR, magnetic, mass spectral, XRD and thermal studies of metal chelates of tenoxicam

    Science.gov (United States)

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

    2007-09-01

    Metal chelates of anti-inflammatory drug, tenoxicam (Ten), are synthesized and characterized using elemental analyses, IR, solid reflectance, magnetic, mass spectra, thermal analyses (TGA and DTA) and X-ray powder diffraction techniques. The chelates are found to have the general formulae [M(H 2L) 2(H 2O) x] (A) 2· yH 2O (where H 2L = neutral Ten, A = Cl in case of Ni(II) and Co(II) or AcO in case of Cu(II) and Zn(II) ions, x = 0-2 and y = 0-2.5) and [M(H 2L) 3](A) z· yH 2O (A = SO 4 in case of Fe(II) ion ( z = 1) or Cl in case of Fe(III) ( z = 3) and y = 0-4). IR spectra reveal that Ten behaves as a neutral bidentate ligand coordinated to the metal ions through the pyridyl- N and carbonyl- O of the amide moiety. The solid reflectance spectra and magnetic moment measurements reveal that these chelates have tetrahedral, square planar and octahedral geometrical structures. Mass spectra are also used to confirm the proposed formulae and the possible fragments resulted from fragmentation of Ten and its Zn(II) and Cu(II) chelates are suggested. The thermal behaviour of the chelates (TG/DTG, DTA) are discussed in detailed manner and revealed that water molecules of crystallization together with anions are removed in the first and second steps while the Ten molecules are removed in the subsequent steps. Different thermodynamic parameters are evaluated and the relative thermal stabilities of the complexes are discussed. X-ray powder diffraction patterns are used to indicate the polymorphic form of Ten and if the complexes have molecular similarity with respect to type of coordination.

  5. Polymer monoliths with chelating functionalities for solid phase extraction of metal ions from water.

    Science.gov (United States)

    Wang, Hongxia; Zhang, Haiyang; Lv, Yongqin; Svec, Frantisek; Tan, Tianwei

    2014-05-23

    Simple devices for the adsorption and preconcentration of metal ions comprising various monolithic polymers have been prepared by in situ polymerization within the 5.5cm long and 5.6mm i.d. polypropylene syringes. Poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith was modified with ethylenediamine to obtain the chelating material. The poly(butyl methacrylate-co-ethylene dimethacrylate) and poly(lauryl methacrylate-co-ethylene dimethacrylate) monoliths were first photografted with glycidyl methacrylate prior to functionalization with ethylenediamine. Alternatively, other chelating functionalities including poly(ethylene imines) varying in molecular weight and shape (linear and branched) as well as lysozyme were also attached to the monolithic supports. We found that the poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith functionalized with ethylenediamine exhibited the best chelating properties characterized with rapid adsorption and a capacity of 111.2mg/g (537μmol/g) for Pb(2+), 38.1mg/g (649μmol/g) for Ni(2+), 69.9mg/g (1100μmol/g) for Cu(2+), and 188.9mg/g (3633μmol/g) for Cr(3+). The very fast desorption was then achieved using 1.0mol/L HNO3 as the eluent. An enrichment factor of 300 was observed for metal ions adsorbed from solutions containing 2ppb of the metal. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Investigation of biologically-designed metal-specific chelators for potential metal recovery and waste remediation applications.

    Energy Technology Data Exchange (ETDEWEB)

    Criscenti, Louise Jacqueline; Ockwig, Nathan W.

    2009-01-01

    Bacteria, algae and plants produce metal-specific chelators to capture required nutrient or toxic trace metals. Biological systems are thought to be very efficient, honed by evolutionary forces over time. Understanding the approaches used by living organisms to select for specific metals in the environment may lead to design of cheaper and more effective approaches for metal recovery and contaminant-metal remediation. In this study, the binding of a common siderophore, desferrioxamine B (DFO-B), to three aqueous metal cations, Fe(II), Fe(III), and UO{sub 2}(VI) was investigated using classical molecular dynamics. DFO-B has three acetohydroxamate groups and a terminal amine group that all deprotonate with increasing pH. For all three metals, complexes with DFO-B (-2) are the most stable and favored under alkaline conditions. Under more acidic conditions, the metal-DFO complexes involve chelation with both acetohydroxamate and acetylamine groups. The approach taken here allows for detailed investigation of metal binding to biologically-designed organic ligands.

  7. 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

  8. Fabrication of chelating diethylenetriaminated pan micro and nano fibers for heavy metal removal

    Directory of Open Access Journals (Sweden)

    Abdouss Majid

    2012-01-01

    Full Text Available In this study, commercial acrylic fibers were modified with diethylenetriamine to prepare metal chelating fibers. The effects of process parameters on the efficiency of the reaction were investigated. FTIR spectroscopy and TGA analysis were used to confirm the chemical changes made to the fibers during the reaction. The ability of the modified fibers for removal of Pb (II, Cu (II and Ce (IV ions from aqueous media was determined. The modified fibers showed a slight decrease in mechanical properties compared to raw ones. Furthermore, the acrylic micro fibers were electrospun to nanofibers and the ability of modified nanofibers for the adsorption of the metal ions was studied.

  9. 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.

  10. A Heat-Resistant and Energetic Metal-Organic Framework Assembled by Chelating Ligand.

    Science.gov (United States)

    Wang, Qianyou; Wang, Shan; Feng, Xiao; Wu, Le; Zhang, Guoying; Zhou, Mingrui; Wang, Bo; Yang, Li

    2017-11-01

    Heat-resistant explosives with high performance and insensitivity to external stimulus or thermal are indispensable in both the military and civilian worlds especially when utilized under harsh conditions. We designed and synthesized a new heat-resistant three-dimensional chelating energetic metal-organic framework (CEMOF-1) by employing 4-amino-4H-1,2,4-triazole-3,5-diol (ATDO) as a ligand. Because of its chelating 3D structural feature, good oxygen balance (-29.58%), and high crystal density (2.234 g cm -3 ), CEMOF-1 demonstrates high decomposition temperature (445 °C), insensitivity to stimulation, and excellent detonation velocity (10.05 km s -1 ) and detonation pressure (49.36 GPa). The advantages of facile synthesis, thermal stability, and powerful explosive performance make CEMOF-1 as a promising candidate for heat-resistant explosives in future applications.

  11. Sorbent extraction of rubeanic acid-metal chelates on a new adsorbent: Sepabeads SP70.

    Science.gov (United States)

    Soylak, Mustafa; Tuzen, Mustafa

    2006-11-02

    A sorbent extraction procedure for lead, iron, cadmium and manganese ions on Sepabeads SP70 adsorption resin has been presented prior to their flame atomic absorption spectrometric determinations. By the passage of aqueous samples including analyte ions-rubeanic acid chelates through Sepabeads SP70 column, metal chelates adsorb quantitatively and almost all matrix elements will pass through the column to drain. The influence of potential interfering ions was also studied. The validation of the method was made though the analysis of LGC 6010 Hard drinking water, SRM 1577b Bovine liver and GBW 07603 Bush branches and leaves standard reference materials (SRM). The method was applied to the determination of analyte ions from various water, wastewater, cow meat and milk, red wine, and tobacco samples with successfully results.

  12. Annihilation electrogenerated chemiluminescence of mixed metal chelates in solution: modulating emission colour by manipulating the energetics

    Science.gov (United States)

    Kerr, Emily; Doeven, Egan H.; Bower, David J.; Donnelly, Paul S.; Connell, Timothy U.

    2015-01-01

    We demonstrate the mixed annihilation electrogenerated chemiluminescence of tris(2,2′-bipyridine)ruthenium(ii) with various cyclometalated iridium(iii) chelates. Compared to mixed ECL systems comprising organic luminophores, the absence of T-route pathways enables effective predictions of the observed ECL based on simple estimations of the exergonicity of the reactions leading to excited state production. Moreover, the multiple, closely spaced reductions and oxidations of the metal chelates provide the ability to finely tune the energetics and therefore the observed emission colour. Distinct emissions from multiple luminophores in the same solution are observed in numerous systems. The relative intensity of these emissions and the overall emission colour are dependent on the particular oxidized and reduced species selected by the applied electrochemical potentials. Finally, these studies offer insights into the importance of electronic factors in the question of whether the reduced or oxidized partner becomes excited in annihilation ECL. PMID:28694941

  13. Effect of metals on Candida albicans growth in the presence of chemical chelators and human abscess fluid.

    Science.gov (United States)

    Sohnle, P G; Hahn, B L; Karmarkar, R

    2001-04-01

    Calprotectin is a calcium- and zinc-binding protein that is present in abscess fluid supernatants and appears to inhibit microbial growth through competition for zinc. In the present study, growth inhibition by chemical chelators was compared with that produced by human abscess fluid to determine whether other chelators, perhaps with different metal specificities, would have the same or different patterns of metal reversibility as abscess fluid. Zinc was found to be more potent than the other metals tested in reversing C. albicans growth inhibition by human abscess fluid and three chemical chelators, even though in some cases the stability constants of certain of these chelators were higher for other metals. For example, in the presence of the chelator diethylenetriaminopentaacetic acid, zinc stimulated Candida growth at a 10-fold lower concentration than did iron, even though this chelator has a stability constant for iron that is almost 10(10) higher than that for zinc. These results suggest that the zinc specificity of calprotectin's C. albicans growth inhibition can best be explained by the marked sensitivity of this organism to zinc deprivation rather than by selective binding of this metal by the protein.

  14. Competition between deferiprone, desferrioxamine and other chelators for iron and the effect of other metals.

    Science.gov (United States)

    Sheppard, L N; Kontoghiorghes, G J

    1993-06-01

    Competition for iron between the leading oral iron chelator deferiprone (L1, 1,2-dimethyl-3-hydroxypyrid-4-one) and desferrioxamine (DF), and the effect of other metals has been studied. Visible spectroscopy was used to estimate the displacement of iron from DF-iron(III) and L1-iron(III) complexes, respectively, by varying quantities of up to 100 molar equivalent of a competing metal ion M+ (Mg2+, Al3+, Ca2+, Mn2+, Co2+, Cu2+, Zn2+ and Pb2+) at physiological pH. Copper and aluminium showed the greatest competition against iron, while magnesium, calcium and manganese had little or no effect and the other metals an intermediate effect. DF showed greater selectivity for iron than L1 under these conditions. An analogous series of experiments carried out using a competing chelator of up to 50 molar equivalent in a place of a competing metal ion showed that 8-hydroxyquinoline, diethylenetriamine-pentaacetic acid (DTPA) and tropolone were more effective at displacing iron from DF-Fe and (L1)3Fe complexes than maltol or omadine. Desferrioxamine was the most efficient competitor against L1. Stoichiometric studies of the L1 complexes of aluminium and copper at pH 7.4 using Job Plots, suggested the formation of (L1)3Al and (L1)2Cu complexes, respectively.

  15. Metal chelate affinity precipitation of RNA and purification of plasmid DNA

    Science.gov (United States)

    Balan, Sindhu; Murphy, Jason; Galaev, Igor; Kumar, Ashok; Fox, George E.; Mattiasson, Bo; Willson, Richard C.

    2003-01-01

    The affinity of metal chelates for amino acids, such as histidine, is widely used in purifying proteins, most notably through six-histidine 'tails'. We have found that metal affinity interactions can also be applied to separation of single-stranded nucleic acids through interactions involving exposed purines. Here we describe a metal affinity precipitation method to resolve RNA from linear and plasmid DNA. A copper-charged copolymer of N-isopropyl acrylamide (NIPAM) and vinyl imidazole (VI) is used to purify plasmid from an alkaline lysate of E. coli. The NIPAM units confer reversible solubility on the copolymer while the imidazole chelates metal ions in a manner accessible to interaction with soluble ligands. RNA was separated from the plasmid by precipitation along with the polymer in the presence of 800 mM NaCl. Bound RNA could be recovered by elution with imidazole and separated from copolymer by a second precipitation step. RNA binding showed a strong dependence on temperature and on the type of buffer used.

  16. Synthesis, Characterization and Antimicrobial Activity of Metal Chelates of 5-[1(H-Benzotriazole methylene]-8-quinolinol

    Directory of Open Access Journals (Sweden)

    H. S. Patel

    2009-01-01

    Full Text Available 5-Chloromethyl-8-quinolinol was condensed stoichiometrically with benzotriazole in presence of potassium carbonate. The resulting 5-[1(H-benzo triazole methylene]-8-quinolinol (BTMQ was characterized by elemental analysis and spectral studies. The transition metal chelates viz. Cu2+, Ni2+, Co3+, Mn2+ and Zn2+ of BTMQ were prepared and characterized by metal-ligand (M:L ratio, IR and reflectance spectral studies and magnetic properties. The antifungal activity of BTMQ and its metal chelates was screened against various fungi. The results show that all these samples are good antifungal agents.

  17. 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.

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

    Science.gov (United States)

    Barankova, Eva; Tan, Xiaoyu; Villalobos, Luis Francisco; Litwiller, Eric; Peinemann, Klaus-Viktor

    2017-03-06

    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 poly-thiosemicarbazide (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. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A new chelating sorbent for metal ion extraction under high saline conditions.

    Science.gov (United States)

    Prabhakaran, D; Subramanian, M S

    2003-05-01

    A new chelating polymeric sorbent was developed by functionalizing Amberlite XAD-16 with 1,3-dimethyl-3-aminopropan-1-ol via a simple condensation mechanism. The newly developed chelating matrix offered a high resin capacity and faster sorption kinetics for the metal ions such as Mn(II), Pb(II), Ni(II), Co(II), Cu(II), Cd(II) and Zn(II). Various physio-chemical parameters like pH-effect, kinetics, eluant volume and flow rate, sample breakthrough volume, matrix interference effect on the metal ion sorption have been studied. The optimum pH range for the sorption of the above mentioned metal ions were 6.0-7.5, 6.0-7.0, 8.0-8.5, 7.0-7.5, 6.5-7.5, 7.5-8.5 and 6.5-7.0, respectively. The resin capacities for Mn(II), Pb(II), Ni(II), Co(II), Cu(II), Cd(II) and Zn(II) were found to be 0.62, 0.23, 0.55, 0.27, 0.46, 0.21 and 0.25 mmol g(-1) of the resin, respectively. The lower limit of detection was 10 ng ml(-1) for Cd(II), 40 ng ml(-1) for Mn(II) and Zn(II), 32 ng ml(-1) for Ni(II), 25 ng ml(-1) for Cu(II) and Co(II) and 20 ng ml(-1) for Pb(II). A high preconcentration value of 300 in the case of Mn(II), Co(II), Ni(II), Cu(II),Cd(II) and a value of 500 and 250 for Pb(II) and Zn(II), respectively, were achieved. A recovery of >98% was obtained for all the metal ions with 4 M HCl as eluting agent except in the case of Cu(II) where in 6 M HCl was necessary. The chelating polymer showed low sorption behavior to alkali and alkaline earth metals and also to various inorganic anionic species present in saline matrix. The method was applied for metal ion determination from water samples like seawater, well water and tap water and also from green leafy vegetable, from certified multivitamin tablets and steel samples.

  20. [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.

  1. 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)

  2. Evaluation of the chelating performance of biopolyelectrolyte green complexes (NIBPEGCs) for wastewater treatment from the metal finishing industry.

    Science.gov (United States)

    López-Maldonado, Eduardo A; Zavala García, Oscar Gabriel; Escobedo, Kevin Cruz; Oropeza-Guzman, Mercedes T

    2017-08-05

    In this paper nonstoichiometric interbiopolyelectrolyte green complexes (NIBPEGCs) were prepared using chitosan (Ch), alginate (AG) and poly(acrylic acid)(PAA). They are proposed as innovative formulations (polyelectrolytes and chelating agents) suitable for the elimination heavy metals contained in wastewater. This application may represent an integral solution for industries rejecting solid and aqueous metallic materials; however, it has not been previously reported. NIBPEGCs physicochemical performance was evaluated based on pH, particle size, surface charge, isoelectric point, dose, coagulation-flocculation kinetics and chemical affinity with seven metal ions. The experimental results showed that NIBPEGCs composed by AG/Ch and PAA/Chitosan have all the three complementary functions: chemical affinity, electrostatic interaction and particle entrapment anticipating more simple operation units to remove heavy metals. Complexes of AG/Ch (negative) were higher performance in removing heavy metals, with a dose window (150-180mg/L), lower dose of 410mg/L PAA/Ch (negative). Investigation of chelating performances of NIBPEGCs show that the efficiency of metal removal is: Ca˃Cr˃Cu˃Pb˃Ni˃Zn˃Cd. Transmittance vs time profiles, metals and zeta potential analysis showed that chelation capacity is the crucial factor to ensure metallic species removal, followed by physical entrapment of the metallic colloids. Integrating all presented results allow to sustain the development of excellent metals removal formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Effective removal of heavy metals from industrial sludge with the aid of a biodegradable chelating ligand GLDA

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qing; Cui, Yanrui; Li, Qilu; Sun, Jianhui, E-mail: sunjh@htu.cn

    2015-02-11

    Highlights: • A novel readily biodegradable chelating ligand was employed to remove heavy metals. • The effects of different conditions on the extraction with GLDA were probed. • Species distribution of metals before and after extraction with GLDA was analyzed. • GLDA was effective for Cd extraction from sludge samples under various conditions. • GLDA offers special insights in the effective removal of heavy metals. - Abstract: Tetrasodium of N,N-bis(carboxymethyl) glutamic acid (GLDA), a novel readily biodegradable chelating ligand, was employed for the first time to remove heavy metals from industrial sludge generated from a local battery company. The extraction of cadmium, nickel, copper, and zinc from battery sludge with the presence of GLDA was studied under different experimental conditions such as contact times, pH values, as well as GLDA concentrations. Species distribution of metals in the sludge sample before and after extraction with GLDA was also analyzed. Current investigation showed that (i) GLDA was effective for Cd extraction from sludge samples under various conditions. (ii) About 89% cadmium, 82% nickel and 84% copper content could be effectively extracted at the molar ratio of GLDA:M(II) = 3:1 and at pH = 4, whereas the removal efficiency of zinc was quite low throughout the experiment. (iii) A variety of parameters, such as contact time, pH values, the concentration of chelating agent, stability constant, as well as species distribution of metals could affect the chelating properties of GLDA.

  4. 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.

  5. 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.

  6. Determination of toxic heavy metals in sea water by FAAS after preconcentration with a novel chelating resin.

    Science.gov (United States)

    Manivannan, D; Biju, V M

    2011-01-01

    A solid phase extraction procedure was developed for preconcentration of toxic heavy metals such as cadmium, cobalt, copper, manganese, lead and zinc in sea water samples. A microcolumn packed with 6-[(4-hydroxyphenyl)diazenyl]naphthalene-2,3-diol-formaldehyde (HPDN-F) resin acts as a sorbent to retain the analyte ions by forming metal chelates. The retained trace level metal was subsequently eluted with 1 mol/L HCl and the acid eluent was analysed by Flame Atomic Absorption Spectrophotometer (FAAS). The HPDN-F chelating resin and its metal chelates were characterized by spectral and thermal analysis. The chelating property of the HPDN-F resin towards divalent metal ions was studied as a function of pH and preconcentration flow rate. The recoveries of cadmium, cobalt, copper, manganese, lead and zinc under the optimum working conditions were above 95%. The relative standard deviations were < 2%. The limits of detection were < 0.1 microg/L. The method presented was applied for the determination of cadmium, cobalt, copper, manganese, lead and zinc in sea water samples.

  7. 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.

  8. 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.

  9. A study of a sandwich conformation in metal chelates based on 1,1-diacetylferrocene bis(aroylhydrazones)

    International Nuclear Information System (INIS)

    Morozov, A.N.; Kogan, V.A.; Lukov, V.V.; Khel'mer, V.Yh.; Mirmil'shtejn, A.S.; Starikov, A.G.; Ovsyannikov, F.M.

    1996-01-01

    Data of IR-, electronic, EXAFS-spectroscopy, cryometry enabled to ascribe the chelate structure to earlier synthesized metal (including Cd) complexes with 1,1'-diacetylferrocene bis(aroylhydrazones). Mentioned methods enabled to establish sphenoid distortion of metallocene fragment. 13 refs.; 3 figs.; 1 tab

  10. 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.

  11. Determination of trace transition metals in environmental matrices by chelation ion chromatography.

    Science.gov (United States)

    Murgia, Sandro M; Selvaggi, Roberta; Poletti, Antonio

    2011-03-01

    Trace transition metals (Fe(3+), Mn, Cu, Cd, Co, Zn, Ni) in environmental samples were analyzed by chelation ion chromatography using a mixed bed ion-exchange column with pyridine-2,6-dicarboxylic acid (PDCA) and oxalic acid as eluent and large volume direct injection (1,000 μl). The two eluents, PDCA and oxalic acid, were tested, and repeatability and detection limits were compared. The total analysis time was ~15 min. The separation with PDCA was more successful than that obtained with acid oxalic. It was observed that utilizing PDCA resulted in lower detection limits, higher repeatability, and a quantitative detection of Cd and Mn, which coelute as a single peak when using the oxalic acid. At last, the PDCA calibration graphs resulted linear (r (2) > 0.999) in the range 0.4-1,000 μg/L. The procedure was applied to the analysis of metals in soils and in water samples. The results obtained from the analysis of natural waters have demonstrated that the method is simple and efficient, therefore, can be used for the determination of metals in natural waters using a continuous and automatic monitoring system.

  12. Extraction of metal ions by melts of chelate-forming reagents

    International Nuclear Information System (INIS)

    Lobanov, F.I.; Leonov, V.A.; Stefanov, A.V.; Gibalo, I.M.

    1977-01-01

    Extraction has been studied of some ions of 4B and 5B subgroup metals (Zr,Hf,Nb and Ta) with the use of melts of chelate-forming reagents (8-oxyquinoline, benzoylacetone, dibenzoylmethane) depending on various factors: hydrogen ion concentration, metal ion, reagent, masking compounds and the ratio between phases. It has been established that in the case of extraction with a melt of 8-oxyquinoline under optimum extraction conditions (pH=5-6) zirconium, hafnium, niobium, and tantalum are extracted quantitatively (to 1.10 -8 g-at/l); extraction with melts of benzoylacetone and dibenzoylmethane yields zirconium, hafnium, and niobium in amounts to nx10 -6 g-at/l. The study of the effect of complexing compounds has shown that tartaric acid does not affect the extraction of Zr,Hf,Nb and Ta; oxalic acid inhibits the extraction of Hf and Ta and does not affect the extraction of Nb. Citric acid does not affect the extraction of Hf, Nb, Ta and somewhat decreases the extraction of Zr

  13. 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.

  14. 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.

  15. Influence of hydrological and geochemical processes on the transport of chelated metals and chromate in fractured shale bedrock.

    Science.gov (United States)

    Jardine, P M; Mehlhorn, T L; Larsen, I L; Bailey, W B; Brooks, S C; Roh, Y; Gwo, J P

    2002-03-01

    Field-scale processes governing the transport of chelated radionuclides in groundwater remain conceptually unclear for highly structured, heterogeneous environments. The objectives of this research were to provide an improved understanding and predictive capability of the hydrological and geochemical mechanisms that control the transport behavior of chelated radionuclides and metals in anoxic subsurface environments that are complicated by fracture flow and matrix diffusion. Our approach involved a long-term, steady-state natural gradient field experiment where nonreactive Br- and reactive 57Co(II)EDTA2- 109CdEDTA2-, and 51Cr(VI) were injected into a fracture zone of a contaminated fractured shale bedrock. The spatial and temporal distribution of the tracer and solutes was monitored for 500 days using an array of groundwater sampling wells instrumented within the fast-flowing fracture regime and a slower flowing matrix regime. The tracers were preferentially transported along strike-parallel fractures coupled with the slow diffusion of significant tracer mass into the bedrock matrix. The chelated radionuclides and metals were significantly retarded by the solid phase with the mechanisms of retardation largely due to redox reactions and sorption coupled with mineral-induced chelate-radionuclide dissociation. The formation of significant Fe(III)EDTA byproduct that accompanied the dissociation of the radionuclide-chelate complexes was believed to be the result of surface interactions with biotite which was the only Fe(III)-bearing mineral phase present in these Fe-reducing environments. These results counter current conceptual models that suggest chelated contaminants move conservatively through Fe-reducing environments since they are devoid of Fe-oxyhydroxides that are known to aggressively compete for chelates in oxic regimes. Modeling results further demonstrated that chelate-radionuclide dissociation reactions were most prevalent along fractures where accelerated

  16. Competitive removal of heavy metal ions from squid oil under isothermal condition by CR11 chelate ion exchanger.

    Science.gov (United States)

    Tavakoli, Omid; Goodarzi, Vahabodin; Saeb, Mohammad Reza; Mahmoodi, Niyaz Mohammad; Borja, Rafael

    2017-07-15

    Heavy metal ions (HMIs) are serious threats to the environment. Sub-critical water treatment was used to mimic contamination of squid oil in aqueous, metal-soap and oil phases. Isothermal adsorption of HMIs (Cu 2+ , Pb 2+ , Cd 2+ and Zn 2+ ) was studied from aqueous phase to oil phase (493, 523, 548, and 573K) for solutions with different initial concentration of HMIs was studied. Decomposition of glycerides into fatty acids was favored at high subcritical temperatures, with metal-soap phase showing the highest chelation ability toward Cu 2+ (96%, isotherm 573K). The removal-ability of HMIs from contaminated oil was performed by CR11 chelate ion exchanger, showing facilitated removal from metal-soap and oil phases at low temperatures compared to general-purpose PEI-chitosan bead and PEI-chitosan fiber sorbents. The chelation behavior of Pb 2+ and Cd 2+ was the same in the OIL, with maximum values of 5.7×10 -3 (mol/l) and 5.0×10 -3 (mol/l) at 573K, respectively. By contrast, concentration of Zn 2+ ion showed a slight increase with increasing temperature due to electrostatic forces between Zn 2+ and active sites of glycerides in oil phase. For oil solution, the selectivity of adsorption for CR11, especially for Zn 2+ , was at least five-fold larger compared to PEI-chitosan bead and PEI-chitosan fiber adsorbents. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Fabrication and characterization of open-tubular CEC modified with tentacle-type metal-chelating polymer chains.

    Science.gov (United States)

    Xu, Liang; Sun, Yan

    2007-06-01

    A novel stationary phase with tentacle-type metal-chelating polymer chains was fabricated for open-tubular CEC. The preparation procedure of the stationary phase included the synthesis of monomer, silanization of capillary inner wall, in situ polymerization, and metal complexation. The effects of initiator concentration and reaction time on the column capacity were investigated. To compare with the tentacle-type metal-chelating capillary column, a monolayer ligand-modified capillary was also prepared. Immobilized copper(II) capacity of the tentacle-type polymer stationary phase was nearly 900 times higher than that of the monolayer one. The electroosmotic mobility was examined for its dependence on pH as well as phosphate and ACN concentrations. The tentacle-type metal-chelating capillary with high ligand capacity has proven to afford better retention and resolution for the separation of phenylalanine, tryptophan, and tyrosine mixtures and three purine derivatives. The separation was considered to be effected by a combination of ligand exchange and electrophoretic mobility.

  18. 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.

  19. Phytochemical Analysis and Metal-chelation Activity of Achillea tenuifolia Lam.

    Science.gov (United States)

    Moradkhani, Shirin; Ayatollahi, Abdul Majid; Ghanadian, Mustafa; Moin, Mohammad Reza; Razavizadeh, Masoud; Shahlaei, Mohsen

    2012-01-01

    Achillea tenuifolia Lam. (Asteraceae) afforded a dichloromethane fraction from which three known compounds β-sitosterol (compound1), 5-hydroxy, 4',6,7- trimethoxy flavone (salvigenin compound 2), and methyl-gallate (compound 3) were isolated for the first time. The structure of isolated compounds was elucidated by different spectroscopic methods. Applying the molar-ratio method, the complexation of salvigenin with Fe (III), Cu(II) and Zn(II), the most abundant type of metal ions in the body, were then evaluated. It was determined that stoichiometric ratio of salvigenin with these cations were as Fe(Salvigenin)2 (H2O)2 and Cu(Salvigenin)2(H2O)2 in methanolic solution without pH control, while zinc ions didn`t form significant complexes. The results were confirmed more, by computational molecular modeling of the structure of proposed ligand-complexes by semi-imperical PM3 calculations, which determined negative heat of formation for the complexes Fe(III) and Cu(II) ions as -689.7 and -573.5, respectively and proposed chelating affinity of salvigenin in the following order: Fe(III) > Cu(II) > Zn(II).

  20. 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.

  1. Functionalization of Cellulose Nanocrystals with PEG-Metal-Chelating Diblock Copolymers via Controlled Conjugation in Aqueous Medium

    Science.gov (United States)

    Guo, Melinda

    The surface of cellulose nanocrystals (CNCs) was successfully functionalized with metal chelating diblock copolymers via HyNic-4FB conjugation. Two types of PEG-metal-chelating block polymers with hydrazinonicotinate acetone hydrazine (HyNic) end groups were synthesized: mPEG-PGlu(DTPA) 18-HyNic and mPEG-PGlu(DTPA)25-HyNic. These two polymers both had a methoxy PEG (M ˜ 2000 Da) block that differed in the mean degree of polymerization of the metal-chelating block. They were characterized by 1H NMR spectroscopy and gel-permeation chromatography (GPC). 4-Formylbenzamide (4FB) groups were introduced onto the surface of CNCs and quantified through their reaction with 2-hydrazinopyridine. The polymers were grafted onto the surface of CNCs via bis-aryl hydrazone bond formation, and the kinetics of this reaction was explored by UV/Vis spectroscopy. The CNCs were also labeled with rhodamine and Alexa FluorRTM 488 dyes. Students in our collaborator's group in Pharmacy are examining applications of these materials as radiotherapeutic agents for cancer treatment.

  2. Determination of molybdenum and vanadium in seawater by carbon furnace atomic absorption spectrometry with metal chelate coprecipitation

    International Nuclear Information System (INIS)

    Fujiwara, Kitao; Morikawa, Toshiki; Fuwa, Keiichiro

    1986-01-01

    Coprecipitation with metal chelate complex formation has been studied for determining molybdenum and vanadium in seawater. As coprecipitation carriers, several pairs of metal ion and chelating agent were applied : Co(II)-ammonium pyrrolydinedithiocarbamate (APDC), Cu(II)-APDC, Cr(VI)-APDC, Co(II)-sodium diethyldithiocarbamate, AI(III)-8-quinolinol, Cu(II)-cupferron, and Ni(II)-dimethylglyoxime. The procedure was as follows : A 100 ml molybdate {Mo(VI)} and metavanadate {V(V)} sample solution was taken to which were added acetate buffer solution. After addition of the carrier metal ion, the pH of the solution was adjusted and the chelating agent was then added. After stood for 1 h, the precipitate was collected by a membrane filter(pore size 0.2 μm), and dissolved in 5 ml of nitric acid(1 mol/l). It was then analyzed by graphite furnace atomic absorption spectrometer. The coprecipitation done with Co(II)-APDC surpassed the others in recoveries of molybdenum and vanadium ; which were 94 ± 3 and 96 ± 3 %, respectively. The minimum detectable amounts in the initial solution were found to be 0.05 μg/l for molybdenum and 0.1 μg/l for vanadium. Molybdenum and vanadium were determined in seawater sampled at the Japan Trench in the North Pacific Ocean. (author)

  3. Identifying sugarcane expressed sequences associated with nutrient transporters and peptide metal chelators

    Directory of Open Access Journals (Sweden)

    Antonio Figueira

    2001-12-01

    Full Text Available Plant nutrient uptake is an active process, requiring energy to accumulate essential elements at higher levels in plant tissues than in the soil solution, while the presence of toxic metals or excess of nutrients requires mechanisms to modulate the accumulation of ions. Genes encoding ion transporters isolated from plants and yeast were used to identify sugarcane putative homologues in the sugarcane expressed sequence tag (SUCEST database. Five cluster consensi with sequence homology to plant high-affinity phosphate transporter genes were identified. One cluster consensus allowed the prediction of a full-length protein containing 541 amino acids, with 81% amino acid identity to the Nicotiana tabacum NtPT1 gene, consisting of 12 membrane-spanning domains divided by a large hydrophilic charged region. Putative homologues to Arabidopsis thaliana micronutrient transporter genes were also detected in some of the SUCEST libraries. Iron uptake in grasses involves the release of the phytosiderophore mugeneic acid (MA which chelate Fe3+ which is then absorbed by a specific transporter. Sugarcane expressed sequence tag (EST homologous to genes coding for three enzymes of the mugeneic acid biosynthetic pathway [nicotianamine synthase; nicotianamine transferase; and putative mugeneic acid synthetase (ids3] and a putative Fe3+-phytosiderophore transporter were detected. Seven sugarcane sequence clusters were identified with strong homology to members of the ZIP gene family (ZIP1, ZIP3, ZIP4, IRT1 and ZNT1, while four clusters homologous to ZIP2 and three to ZAT were found. Homologues to members of another gene family, Nramp, which code for broad-specificity transition metal transporters were also detected with constitutive expression. Partial transcripts homologous to genes encoding gamma-glutamylcysteine synthetase, glutathione synthetase, and phytochelatin synthase (responsible for biosynthesis of the metal chelator phytochelatin and all four types of the

  4. Influence of chelation ratio of metal alkoxides on aging of PZT 53/47 ...

    Indian Academy of Sciences (India)

    based synthesis routes, generally demands the use of chelating agents in order to avoid fast hydrolysis and also to allow an easier manipulation of intermediates as well as final solutions. Under these conditions, stability issues sometimes can be ...

  5. Chelates for Micronutrient Nutrition among Crops

    Indian Academy of Sciences (India)

    lated metals could supply many of the micronutrient require- ments of plants. These chelates find use in a wide variety of agricultural crops. Applications for chelates vary from fertilizer additives, seed dressing to foliar sprays and hydroponics. Chelates and Chelating Agents. A chelate describes a kind of organic chemical ...

  6. 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.

  7. 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.

  8. Iron Chelation

    Science.gov (United States)

    Skip to main content Menu Donate Treatments Therapies Iron Chelation Iron chelation therapy is the main treatment ... have iron overload and need treatment. What is iron overload? Iron chelation therapy is used when you ...

  9. 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

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

    Science.gov (United States)

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

    2013-09-15

    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. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. 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+).

  12. 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)

  13. 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'-bipyridine...... better accommodated in the receptors than polar groups. The new analog brominated terpyridine (29) resulted in the highest chelator potencies observed so far CCR1 (EC50: 0.49 μM) and CCR8 (EC50: 0.28 μM). Furthermore, we identified the first selective CCR5 agonist chelator, meta dithiomethylated...

  14. 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).

  15. Influence of chelation ratio of metal alkoxides on aging of PZT 53/47 ...

    Indian Academy of Sciences (India)

    Administrator

    Time evolution of mean particle size for the most prominent distribution peak of every R-chelated sample under study is depicted in figure 4, where arrows indicate the 'unimodal age' on each case. As a general tendency, precursor particles are well below the 10 nm range, which is an interesting feature with an immediate ...

  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. Investigations on organic fungicides. XI. The Role of metals and chelating agents in the fungitoxic action of sodium dimethyldithiocarbamate (NaDDC)

    NARCIS (Netherlands)

    Kaars Sijpesteijn, A.; Janssen, M.J.; Kerk, G.J.M. van der

    1957-01-01

    1. 1. The role of metals and chelating agents in the fungitoxic action of sodium dimethyldithiocarbamate (NaDDC) has been studied using Aspergillus niger as a test mould. 2. 2. In liquid glucose mineral salts medium containing only traces of heavy metals NaDDC does not produce a “first zone of

  18. 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.)

  19. Sorption studies of heavy metal ions on a novel chelating resin and its application in the stripping of mercury (II).

    Science.gov (United States)

    Joseph, L; Sivasankara Pillai, V N

    1987-01-01

    A chelating resin containing a stable thiol group was synthesised, using polystyrene as the starting material. The resin is stable towards conc. HCl, 0.1M HNO(3) and 0.1M NaOH. The resin shows affinity towards Ag(+), Hg(2+), Bi(3+), Pb(2+), Cu(2+), Zn(2+) and Cd(2+). Extraction of these metal ions as a function of pH, kinetics of exchange and breakthrough capacities is evaluated. The selectivity of the resin for the metal ions is in the order Ag(+) > Hg2+ > Cu2+ > Pb2+ > Cd2+ > Zn2+. The equilibrium constants for exchange and kinetics of exchange are favourable for the recovery of mercury from lean sources. Application of the resin in the stripping of mercury from chlor-alkali plant affluent, and in the enrichment of mercury from seawater, have been investigated. Mercury sorbed resin can be regenerated using 5% thiourea in 0.1M HCl.

  20. 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

  1. 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.

  2. Characterization of aquatic humic substances and their metal complexes by immobilized metal-chelate affinity chromatography on iron(III)-loaded ion exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Burba, P.; Jakubowski, B.; Kuckuk, R. [Institut fuer Spektrochemie und Angewandte Spektroskopie e.V., Dortmund (Germany); Kuellmer, K.; Heumann, K.G. [Mainz Univ. (Germany). Inst. fuer Anorganische Chemie und Analytische Chemie

    2000-12-01

    The analytical fractionation of aquatic humic substances (HS) by means of immobilized metal-chelate affinity chromatography (IMAC) on metal-loaded chelating ion exchangers is described. The cellulose HYPHAN, loaded with different trivalent ions, and the chelate exchanger Chelex 100, loaded to 90% of its capacity with Fe(III), were used. The cellulose HYPHAN, loaded with 2% Fe(III), resulted in HS distribution coefficients K{sub d}of up to 10 {sup 3.7} mL/g at pH 4.0 continuously decreasing down to 10 {sup 1.5} at pH 12, which were appropriate for HS fractionation by a pH-depending chromatographic procedure. Similar distribution coefficients K {sub d} were obtained for HS sorption onto Fe(III)-loaded Chelex 100. On the basis of Fe-loaded HYPHAN both, a low-pressure and high-pressure IMAC technique, were developed for the fractionation of dissolved HS applying a buffer-based pH gradient for their gradual elution between pH 4.0 and 12.0. By coupling the Chelex 100 column under high-pressure conditions with an inductively coupled plasma mass spectrometer an on-line characterization of HS metal species could be achieved. Using these fractionation procedures a number of reference HS were characterized. Accordingly, the HA (humic acids) and FA (fulvic acids) studied could be discriminated into up to 6 fractions by applying cellulose HYPHAN, significantly differing in their Cu(II) complexation capacity but hardly in their substructures assessed by conventional FTIR. In the case of using Chelex 100 exchanger resin two major UV active HS fractions were obtained, which significantly differ in their complexation properties for Cu(II) and Pb(II), respectively. (orig.)

  3. Synthesis of tentacle-type magnetic beads as immobilized metal-chelate affinity support for cytochrome c adsorption.

    Science.gov (United States)

    Türkmen, Deniz; Yavuz, Handan; Denizli, Adil

    2006-03-30

    Magnetic poly(2-hydroxyethylmethacrylate) (mPHEMA) beads with an average diameter of 100-140 microm were produced by suspension polymerization in the presence of magnetite particles (i.e. Fe3O4). Specific surface area and average pore size of the magnetic beads was found to be 50 m2/g and 819 nm, respectively. Ester groups in the mPHEMA structure were converted to imine groups by reacting with poly(ethyleneimine) (PEI) in the presence of NaH. Amino (-NH2) content of PEI-attached mPHEMA beads was determined as 102 mg PEI/g. Then, Cu2+ ions were chelated on the magnetic beads in the range of 20-793 micromol Cu2+/g. Cytochrome c (cyt c) adsorption was performed on the metal chelating beads from aqueous solutions containing different amounts of cyt c at different pHs, Cu2+ loadings and temperatures. Cyt c adsorption on the mPHEMA/PEI beads was 4.6 mg/g. Cu2+ chelation increased the cyt c adsorption significantly (40.1 mg/g). Adsorption capacity increased with Cu2+ loading and then reached a saturation value. Cyt c adsorption decreased with increasing temperature. Cyt c molecules could be reversibly adsorbed and eluted ten times with the magnetic adsorbents without noticeable loss in their cyt c adsorption capacity. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium capacity and correlation coefficients. Results suggest that chemisorption processes could be the rate-limiting step in the adsorption process. In the last part of this article, cyt c adsorption experiments were performed in a magnetically stabilized fluidized bed (MSFB) system at optimum conditions determined from the batch experiments. The adsorption capacity decreased significantly from 46.8 to 15.4 mg/g polymer with the increase of the flow-rate from 0.5 to 4.0 ml/min. The resulting magnetic chelator beads possessed excellent long-term storage stability.

  4. Heavy metals in the spinal cord of normal rats and of animals treated with chelating agents

    DEFF Research Database (Denmark)

    Schrøder, H D; Fjerdingstad, E; Danscher, G

    1978-01-01

    of various levels along the cranio-caudal axis of the rat spinal cord revealed differences in the heavy metal content. The Timm sulfide silver staining method has demonstrated that metals in the spinal cord have a distinct regional distribution. To obtain a differentiation between the stainable metals...

  5. 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.

  6. 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

    The clinical value of current and future nanomedicines can be improved by introducing patient selection strategies based on noninvasive sensitive whole-body imaging techniques such as positron emission tomography (PET). Thus, a broad method to radiolabel and track preformed nanomedicines...... such as liposomal drugs with PET radionuclides will have a wide impact in nanomedicine. Here, we introduce a simple and efficient PET radiolabeling method that exploits the metal-chelating properties of certain drugs (e.g., bisphosphonates such as alendronate and anthracyclines such as doxorubicin) and widely used...... ionophores to achieve excellent radiolabeling yields, purities, and stabilities with 89Zr, 52Mn, and 64Cu, and without the requirement of modification of the nanomedicine components. In a model of metastatic breast cancer, we demonstrate that this technique allows quantification of the biodistribution...

  7. 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.

  8. Antioxidant effects of coumarins include direct radical scavenging, metal chelation and inhibition of ROS-producing enzymes.

    Science.gov (United States)

    Filipský, Tomáš; Říha, Michal; Macáková, Kateřina; Anzenbacherová, Eva; Karlíčková, Jana; Mladěnka, Přemysl

    2015-01-01

    Coumarins represent a large group of 1,2-benzopyrone derivatives which have been identified in many natural sources and synthetized as well. Several studies have shown that their antioxidant capacity is not based only on direct scavenging of reactive oxygen and nitrogen species (RONS) but other mechanisms are also involved. These include: a) the chelation of transient metals iron and copper, which are known to catalyse the Fenton reaction; and b) the inhibition of RONS-producing enzymes (e.g. xanthine oxidase, myeloperoxidase and lipoxygenase), suggesting that mechanism(s) involved on cellular level are complex and synergistic. Moreover, many factors must be taken into account when analysing structure-antioxidant capacity relationships of coumarins due to different in vitro/in vivo methodological approaches. The structural features necessary for the direct RONS scavenging and metal chelation are apparently similar and the ideal structures are 6,7-dihydroxy- or 7,8-dihydroxycoumarins. However, the clinical outcome is unknown, because these coumarins are able to reduce copper and iron, and may thus paradoxically potentiate the Fenton chemistry. The similar structural features appear to be associated with inhibition of lipoxygenase, probably due to interference with iron in its active site. Contrarily, 6,7-dihydroxycoumarin seems to be the most active coumarin in the inhibition of xanthine oxidase while its derivative bearing the 4-methyl group or 7,8-dihydroxycoumarin are less active or inactive. In addition, coumarins may hinder the induction of inducible NO-synthase and cyclooxygenase- 2. Sparse data on inhibition of myeloperoxidase do not enable any clear conclusion, but some coumarins may block it.

  9. 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.'

  10. Chelating polymer-based membranes. Preparation and use for metal ion scavenging and sorption of murine immunoglobulin G by immobilized Ni(II) ions

    Czech Academy of Sciences Publication Activity Database

    Kráčalíková-Mészárosová, Kateřina; Bleha, Miroslav

    2008-01-01

    Roč. 61, č. 2 (2008), s. 147-156 ISSN 0170-0839 R&D Projects: GA ČR GA203/02/1327 Institutional research plan: CEZ:AV0Z40500505 Keywords : chelating * membrane * sorption * metal ion Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.127, year: 2008

  11. 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...

  12. Sequential application of chelating agents and innovative surfactants for the enhanced electroremediation of real sediments from toxic metals and PAHs.

    Science.gov (United States)

    Hahladakis, John N; Lekkas, Nikolaos; Smponias, Andreas; Gidarakos, Evangelos

    2014-06-01

    This study focused on the sequential application of a chelating agent (citric acid) followed by a surfactant in the simultaneous electroremediation of real contaminated sediments from toxic metals and Polycyclic Aromatic Hydrocarbons (PAHs). Furthermore, the efficiency evaluation of two innovative non-ionic surfactants, commercially known as Poloxamer 407 and Nonidet P40, was investigated. The results indicated a removal efficacy of approximately 43% and 48% for the summation of PAHs (SUM PAHs), respectively for the aforementioned surfactants, much better than the one obtained by the use of Tween 80 (nearly 21%). Individual PAHs (e.g. fluorene) were removed in percentages that reached almost 84% and 92% in the respective electrokinetic experiments when these new surfactants were introduced. In addition, the combined-enhanced sequential electrokinetic treatment with citric acid improved dramatically the removal of Zn and As, compared to the unenhanced run, but did not favor the other toxic metals examined. Since no improvement in metal removal percentages occurred when Tween 80 was used, significant contribution to this matter should also be attributed to the solubilization capacity of these innovative, in electrokinetic remediation, non-ionic surfactants. Copyright © 2013 Elsevier Ltd. All rights reserved.

  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. Preparation of Amidoxime Polyacrylonitrile Chelating Nanofibers and Their Application for Adsorption of Metal Ions.

    Science.gov (United States)

    Huang, Fenglin; Xu, Yunfei; Liao, Shiqin; Yang, Dawei; Hsieh, You-Lo; Wei, Qufu

    2013-03-11

    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 Cu 2+ and Fe 3+ 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 Cu 2+ and Fe 3+ ions fitted particularly well with the Langmuir isotherm. The maximal adsorption capacities of Cu 2+ and Fe 3+ ions were 215.18 and 221.37 mg/g, respectively.

  15. 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.

  16. 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.

  17. 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.

  18. Single-step coacervate-mediated preconcentration of metals and metal-chelates in supramolecular vesicular surfactant assemblies and determination by flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Tsogas, George Z.; Giokas, Dimosthenis L.; Paleologos, Evangelos K.; Vlessidis, Athanasios G.; Evmiridis, Nicholaos P.

    2005-01-01

    The use of ionic surfactant supramolecular aggregates is described, as means for accomplishing the concentration of analytes with different polarities using the same extraction pattern. The proposed method is based on the phase separation of an anionic surfactant through the formation of perplexed lamellar phases, allowing for the extraction of hydrated metal cations by complexation and metal-chelates by hydrophobic interactions. The data suggest that both extraction and phase separation are controlled by the presence of ionic surfactant as a function of the degree of phase divergence from the lamellar to bilayer phase. This again is determined by the composition of the phase-forming parameters, these are the surfactant concentration, the kind and amount of metallic counterparts and ionic strength. On the basis of these findings, the proposed method was successfully applied to the determination of metal species in natural waters. The limits of detection were easily brought down to the low microgram per liter levels by simply preconcentrating 10 mL of sample volume in the presence of at least 0.45% (w/v) of anionic surfactant. The method provided extraction recoveries higher than 94.0% with standard deviations well below 7.0%

  19. Metal chelates of 2-hydroxy-4-methylthiobutanoic acid in animal feeding. Part 2: Further characterizations, in vitro and in vivo investigations.

    Science.gov (United States)

    Predieri, Giovanni; Elviri, Lisa; Tegoni, Matteo; Zagnoni, Ingrid; Cinti, Enrico; Biagi, Giacomo; Ferruzza, Simonetta; Leonardi, Giuliano

    2005-02-01

    The alpha-hydroxyacid 2-hydroxy-4-methylthiobutanoic acid (the so-called methionine hydroxy-analogue, MHA), largely used in animal nutrition as a source of methionine, forms stable metal chelates with divalent metals of formula [{CH(3)SCH(2) CH(2)CH(OH)COO}(2)M].nH(2)O. Protonation and iron(III) and copper(II) complex formation constants have been determined by potentiometry at 25 degrees C. Distribution diagrams show that no free Fe(3+) cations are present in solution at pH>2.5. ESI-MS (Electron-Spray Ionization Mass Spectrometry) investigations carried out both on iron and zinc complexes in solution have evidenced various species with different MHA/metal ratios. In vivo trials were carried out with rats. After receiving a zinc-deficient diet for 3 weeks, animals were fed the same diet added with zinc sulfate or zinc/MHA chelate; the zinc content of faeces was higher (+45%; P<0.05) in sulfate fed rats, whereas zinc retention was higher (+61%; P<0.05) in the Zn/MHA diet. Experiments in vitro with human intestinal Caco-2 cells indicated that the MHA/Fe chelate was taken up by the cells without any apparent toxic effect. The iron uptake was higher than that of iron nitrilotriacetate (Fe(3+)NTA), an effective chelate for delivering iron to milk diets. In conclusion, these data indicate that the use of MHA chelates could be a valuable tool to increase bioavailability of trace minerals and reduce the environmental impact of animal manure.

  20. Conversion of agonist site to metal-ion chelator site in the beta(2)-adrenergic receptor

    DEFF Research Database (Denmark)

    Elling, C E; Thirstrup, K; Holst, Birgitte

    1999-01-01

    Previously metal-ion sites have been used as structural and functional probes in seven transmembrane receptors (7TM), but as yet all the engineered sites have been inactivating. Based on presumed agonist interaction points in transmembrane III (TM-III) and -VII of the beta(2)-adrenergic receptor,...... as generic, pharmacologic tools to switch 7TM receptors with engineered metal-ion sites on or off at will.......Previously metal-ion sites have been used as structural and functional probes in seven transmembrane receptors (7TM), but as yet all the engineered sites have been inactivating. Based on presumed agonist interaction points in transmembrane III (TM-III) and -VII of the beta(2)-adrenergic receptor......, in this paper we construct an activating metal-ion site between the amine-binding Asp-113 in TM-III-or a His residue introduced at this position-and a Cys residue substituted for Asn-312 in TM-VII. No increase in constitutive activity was observed in the mutant receptors. Signal transduction was activated...

  1. Biphasic catalysis using amphiphilic polyphenols-chelated noble metals as highly active and selective catalysts

    Science.gov (United States)

    Mao, Hui; Yu, Hong; Chen, Jing; Liao, Xuepin

    2013-01-01

    In the field of catalysis, it is highly desired to develop novel catalysts that combine the advantages of both homogeneous and heterogeneous catalysts. Here we disclose that the use of plant pholyphenol as amphiphilic large molecule ligand/stabilizer allows for the preparation of noble metal complex and noble metal nanoparticle catalysts. These catalysts are found to be highly selective and active in aqueous-organic biphasic catalysis of cinnamaldehyde and quinoline, and can be reused at least 3 times without significant loss of activity. Moreover, the catalytic activity and reusability of the catalysts can be rationally controlled by simply adjusting the content of polyphenols in the catalysts. Our strategy may be extended to design a wide range of aqueous-organic biphasic catalysis system. PMID:23863916

  2. Biphasic catalysis using amphiphilic polyphenols-chelated noble metals as highly active and selective catalysts.

    Science.gov (United States)

    Mao, Hui; Yu, Hong; Chen, Jing; Liao, Xuepin

    2013-01-01

    In the field of catalysis, it is highly desired to develop novel catalysts that combine the advantages of both homogeneous and heterogeneous catalysts. Here we disclose that the use of plant polyphenol as amphiphilic large molecule ligand/stabilizer allows for the preparation of noble metal complex and noble metal nanoparticle catalysts. These catalysts are found to be highly selective and active in aqueous-organic biphasic catalysis of cinnamaldehyde and quinoline, and can be reused at least 3 times without significant loss of activity. Moreover, the catalytic activity and reusability of the catalysts can be rationally controlled by simply adjusting the content of polyphenols in the catalysts. Our strategy may be extended to design a wide range of aqueous-organic biphasic catalysis system.

  3. Phytochemical Analysis and Metal-chelation Activity of Achillea tenuifolia Lam.

    OpenAIRE

    Moradkhani, Shirin; Ayatollahi, Abdul Majid; Ghanadian, Mustafa; Moin, Mohammad Reza; Razavizadeh, Masoud; Shahlaei, Mohsen

    2012-01-01

    Achillea tenuifolia Lam. (Asteraceae) afforded a dichloromethane fraction from which three known compounds ?-sitosterol (compound1), 5-hydroxy, 4',6,7? trimethoxy flavone (salvigenin compound 2), and methyl-gallate (compound 3) were isolated for the first time. The structure of isolated compounds was elucidated by different spectroscopic methods. Applying the molar-ratio method, the complexation of salvigenin with Fe (III), Cu(II) and Zn(II), the most abundant type of metal ions in the body, ...

  4. The effect of divalent metal chelators and cadmium on serum phosphotriesterase, lactonase and arylesterase activities of paraoxonase 1.

    Science.gov (United States)

    Bizoń, Anna; Milnerowicz, Halina

    2018-03-01

    Paraoxonase 1 (PON1) is calcium dependent enzyme involved in many functions in human body. PON1 is synthesized in the liver and secreted to the bloodstream where bounds high-density lipoproteins (HDL). Association of PON1 with HDL increases the enzyme stability and biological activities. PON1 have three different activities: phosphotriesterase, lactonase and arylesterase. Until now there is now commercial available kits to determine these three PON1 activities. Also there is no date about stability of PON1 in serum after storage condition. We have elaborated the optimal conditions for determination of PON1 activities in serum using manual procedure as well as the best storage temperature of human serum for determination of PON1 activities. We have also confirmed that PON1 in serum is associated with HDL. Additionally we have investigated the effect of D-penicillamine, ethylenediaminetetraacetic acid and cadmium chloride on PON1 activities in human serum. D-penicillamine and ethylenediaminetetraacetic acid in therapeutic doses as well as cadmium chloride in toxic doses decrease PON1 activities in human serum when compared to non-treated serum. D-penicillamine as metal chelator inhibits much stronger PON1 activities than ethylenediaminetetraacetic acid. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. In Vitro Antioxidant versus Metal Ion Chelating Properties of Flavonoids: A Structure-Activity Investigation

    Science.gov (United States)

    Cherrak, Sabri Ahmed; Mokhtari-Soulimane, Nassima; Berroukeche, Farid; Bensenane, Bachir; Cherbonnel, Angéline; Merzouk, Hafida; Elhabiri, Mourad

    2016-01-01

    Natural flavonoids such as quercetin, (+)catechin and rutin as well as four methoxylated derivatives of quercetin used as models were investigated to elucidate their impact on the oxidant and antioxidant status of human red blood cells (RBCs). The impact of these compounds against metal toxicity was studied as well as their antiradical activities with DPPH assay. Antihemolytic experiments were conducted on quercetin, (+)catechin and rutin with excess of Fe, Cu and Zn (400 μM), and the oxidant (malondialdehyde, carbonyl proteins) and antioxidant (reduced glutathione, catalase activity) markers were evaluated. The results showed that Fe and Zn have the highest prooxidant effect (37 and 33% of hemolysis, respectively). Quercetin, rutin and (+)catechin exhibited strong antioxidant properties toward Fe, but this effect was decreased with respect to Zn ions. However, the Cu showed a weak antioxidant effect at the highest flavonoid concentration (200 μM), while a prooxidant effect was observed at the lowest flavonoid concentration (100 μM). These results are in agreement with the physico-chemical and antiradical data which demonstrated that binding of the metal ions (for FeNTA: (+)Catechin, KLFeNTA = 1.6(1) × 106 M-1 > Rutin, KLFeNTA = 2.0(9) × 105 M-1 > Quercetin, KLFeNTA = 1.0(7) × 105 M-1 > Q35OH, KLFeNTA = 6.3(8.7) × 104 M-1 > Quercetin3’4’OH and Quercetin 3OH, KLFeNTA ~ 2 × 104 M-1) reflects the (anti)oxidant status of the RBCs. This study reveals that flavonoids have both prooxidant and antioxidant activity depending on the nature and concentration of the flavonoids and metal ions. PMID:27788249

  6. Closed vessel miniaturized microwave assisted chelating extraction for determination of trace metals in plant materials

    Science.gov (United States)

    Czarnecki, Sezin; Duering, Rolf-Alexander

    2013-04-01

    In recent years, the use of closed vessel microwave assisted extraction (MAE) for plant samples has shown increasing research interest which will probably substitute conventional procedures in the future due to their general disadvantages including consumption of time and solvents. The objective of this study was to demonstrate an innovative miniaturized closed vessel microwave assisted extraction (µMAE) method under the use of EDTA (µMAE-EDTA) to determine metal contents (Cd, Co, Cu, Mn, Ni, Pb, Zn) in plant samples (Lolio-Cynosuretum) by inductively coupled plasma-optical emission spectrometry (ICP-OES). Validation of the method was done by comparison of the results with another miniaturized closed vessel microwave HNO3 method (µMAE-H) and with two other macro scale MAE procedures (MAE-H and MAE-EDTA) which were applied by using a mixture of nitric acid (HNO3) and hydrogen peroxide (H2O2) (MAE-H) and EDTA (MAE-EDTA), respectively. The already established MAE-H method is taken into consideration as a reference validation MAE method for plant material. A conventional plant extraction (CE) method, based on dry ashing and dissolving of the plant material in HNO3, was used as a confidence comparative method. Certified plant reference materials (CRMs) were used for comparison of recovery rates from different extraction protocols. This allowed the validation of the applicability of the µMAE-EDTA procedure. For 36 real plant samples with triplicates each, µMAE-EDTA showed the same extraction yields as the MAE-H in the determination of Cd, Co, Cu, Mn, Ni, Pb, and Zn contents in plant samples. Analytical parameters in µMAE-EDTA should be further investigated and adapted for other metals of interest. By the reduction and elimination of the use of hazardous chemicals in environmental analysis and thus allowing a better understanding of metal distribution and accumulation process in plants and also the metal transfer from soil to plants and into the food chain, µ

  7. 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.

  8. Synthesis of crescent aromatic oligoamides with preorganized chelating groups and their extraction towards transition metal ions

    International Nuclear Information System (INIS)

    Yang, Xinshi; Chen, Long; Yang, Yongan; He, Youzhou; Zou, Shuliang; Feng, Wen; Yang, Yuanyou; Liu, Ning; Liao, Jiali; Yuan, Lihua

    2012-01-01

    Highlights: ► Three crescent aromatic oligoamides were designed and synthesized. ► Selective Hg 2+ removal was achieved with high efficiency in solvent extraction. ► The stoichiometry of the extracted species was approximately 1:1 (L:M). ► The extraction constant (log K ex ) was determined to be 10.2. - Abstract: Three crescent aromatic oligoamides 1–3 with their backbones rigidified by intramolecular hydrogen bonds were designed and synthesized. The liquid–liquid extraction by these compounds has been investigated using UV–vis spectrometry towards Pb 2+ picrate and some transition metal picrates including Ag + , Hg 2+ , Cd 2+ , Zn 2+ , Cu 2+ , Co 2+ , Ni 2+ salts. The results revealed higher selectivity and efficiency towards Hg 2+ over other metal cations; pentameric ligand 1 with six oxygen donor atoms provided the highest extractability of 83.3%, while dimeric ligand 3 extracted almost exclusively Hg 2+ . The stoichiometry of the extracted complex between ligand 1 and Hg 2+ , and the extraction constant (log K ex ) were determined in solvent extraction.

  9. RECOVERY OF CYCLODEXTRIN GLUCANOTRANSFERASE (CGTase USING IMMOBILIZED METAL CHELATING AFFINITY CHROMATOGRAPHY

    Directory of Open Access Journals (Sweden)

    M. Sivapragasam

    2015-03-01

    Full Text Available Abstract Immobilized metal affinity chromatography (IMAC was chosen as a method of purification for the recovery of CGTase from E. coli homogenate. E. coli harbouring the Bacillus sp. G1 gene expressed extracellularly secreted CGTase into ampicillin supplied LB broth. Culture was pre-purified using SnakeSkin dialysis tubing (3.5 MWCO with an enzyme activity of 147.80 U/mL. Three strategies (A, B and C were employed for the purification of CGTase using column adsorption chromatography with Ni2+-Sepharose resin. Strategy A employed an elution buffer of 50 mM EDTA, pH 7, Strategy B used 0.1 M imidazole, pH 7 and Strategy C employed 45 mM imidazole pH 7 as the elution buffer. Strategy C was found to be most suitable yielding a total CGTase recovery of 87.04% from an initial activity of 147.80 U/mL.

  10. Synthesis, Characterization and Some Properties of Chelating Polymers for Metal Ion Sorption

    International Nuclear Information System (INIS)

    Mohamed, A.S.A.

    2010-01-01

    Ion-exchange membranes have been prepared by radiation induced grafting using simultaneous technique based on low cost starting material and established process technologies. Methacrylic acid (MAA) and styrene (Sty) were selected as the grafted monomers to provide two different types of functional groups. Currently; there is much on going research for developing non fluorinated polymers with better performance and lower cost as alternative ion exchange membrane materials. The polymer chosen for this study is low density polyethylene (LDPE) film of two different thicknesses (40 and 70μm). The influence of grafting conditions, i.e. the effect of total irradiation dose and comonomer concentration and compositions have been investigated. These are important parameters in correlation with the grafting yield because they can markedly influence the composition of the resulting copolymer. Once grafted, the materials were readily sulfonated using concentrated sulfuric acid or chlorosulfonic acid in dichloroethane to produce a selection of graft copolymers with performer properties. The grafting and sulfonation of the membranes were confirmed by (FTIR) X-ray diffraction (XRD) and thermal analysis (TGA, DSC). The physicochemical properties of the prepared membranes such as, ion exchange capacity (IEC), equilibrium swelling and electrical conductivity of the grafted membranes and their derivatives were investigated as a function of composition and degree of grafting. The range of ion exchange capacities obtained with different degrees of grafting of MAA/Sty of composition (50/50) that sulfonated with sulfuric acid was in the range of 1.9-3.4 meq/g, whenever, for membranes that sulfonated with chlorosulfonic acid the IEC of 4.2 meq/g was achieved which is better than most of the commercially available membranes in addition to their low cost. The possibility of practicable use of membranes in various fields, such as the removal of some heavy metal ions is investigated.

  11. Field-portable and automated immunosensors for hexavalent uranium, other heavy metals and chelators. Final Report

    International Nuclear Information System (INIS)

    Blake, Diane A.

    2009-01-01

    This is the final technical report for this 10-year project. A better understanding of in situ bioremediation processes and the development of strategies to enhance bacterial remediation of contaminated sites depend either directly or indirectly upon accurate detection and measurement of organics, metal and other toxic elements prior to, during and following the remediation process. Detection and measurement costs are presently high due to the complex methodologies required for analysis. Remediation costs could be significantly reduced through the use of rapid, simple on-site methods. The cost of laboratory analysis continues to climb and the outlay for the assessment of a single site can frequently reach hundreds of thousands of dollars. One estimate suggests that the use of low cost field methods (defined as less than $100/test) with 5-20% standard laboratory confirmation could reduce analytical costs by greater than 70%. Perhaps as important as the cost of analysis is ability to obtain data about the remediation process in near real-time. The instruments normally used for environmental analysis of uranium (atomic absorption spectrophotometer, inductive coupled plasma emission spectrometer, IC-MS and kinetic phosphorescence analyzer) or can be quite expensive; these instruments are thus usually located only in centralized facilities. Environmental samples must therefore be transported to these facilities and often wait in a queue before they can be analyzed. Both sample transport and time-in-queue lead to long turn-around times (days to weeks). Such long turn-around times are especially worrisome during site remediation, especially when an unexpected finding might dictate a change in the methodologies being employed at the site. The goal of this project was to develop sensors that could yield reliable data in near realtime (< 1 hour) be field-ready (ie, simple, durable and accurate) and present low costs (<< $100/assay and <$5,000 for the initial equipment

  12. 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.

  13. 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.

  14. 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.

  15. 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.

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

    Science.gov (United States)

    Jing, XiaoSheng; Liu, FuQiang; Yang, Xin; Ling, PanPan; Li, LanJuan; Long, Chao; Li, AiMin

    2009-08-15

    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 DeltaH(o), DeltaS(o) and DeltaG(o) were also calculated from graphical interpretation of the experimental data. The standard heats of adsorption (DeltaH(o)) were found to be endothermic and the entropy change values (DeltaS(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 DeltaG(o) indicated that adsorption processes for all tested metal ions onto PSDC were spontaneous.

  17. Synthesis of polyglutamide-based metal-chelating polymers and their site-specific conjugation to trastuzumab for auger electron radioimmunotherapy.

    Science.gov (United States)

    Lu, Yijie; Ngo Ndjock Mbong, Ghislaine; Liu, Peng; Chan, Conrad; Cai, Zhongli; Weinrich, Dirk; Boyle, Amanda J; Reilly, Raymond M; Winnik, Mitchell A

    2014-06-09

    Three types of metal-chelating polymers (MCPs) with hydrazide end groups were synthesized. (1) The first set of polymers (the F-series) was synthesized with a furan end group, and all of the pendant groups along the chain carried only a diethylenetriaminepentaacetic acid (DTPA) metal-chelating functionality. The hydrazide was introduced via a Diels-Alder reaction between the furan and 3,3'-N-[ε-maleimidocaproic acid] hydrazide (EMCH). (2) The P-series polymers was designed to carry several copies of a nuclear-localization peptide sequence (NLS peptides, CGYGPKKKRKVGG, harboring the NLS from the simian virus 40 large T-antigen) in addition to the DTPA metal-chelating groups. (3) The third type of polymer (the P-Py series) was a variation of the P-series polymers but with the introduction of a small number of pyrene chromophores along the backbone to allow for UV measurement of the incorporation of the MCPs into trastuzumab (tmab). These hydrazide-terminated polymers were site-specifically conjugated to aldehyde groups generated by NaIO4 oxidation of the pendant glycan in the Fc domain of tmab. The immunoconjugates were radiolabeled with (111)In and analyzed by SE-HPLC to confirm the attachment of the polymer to the antibody. HER2 binding assays demonstrated that neither the MCPs nor the presence of the NLS peptides interfered with specific antigen recognition on SK-Br-3 cells, although nonspecific binding was increased by polymer conjugation. Our results suggest that MCPs can be site-specifically attached to antibodies via oxidized glycans in the Fc domain and labeled with (111)In to construct radioimmunoconjugates with preserved immunoreactivity.

  18. Effect of Metal Chelators on γ-Secretase Indicates That Calcium and Magnesium Ions Facilitate Cleavage of Alzheimer Amyloid Precursor Substrate

    Directory of Open Access Journals (Sweden)

    Michael Ho

    2011-01-01

    Full Text Available Gamma-secretase is involved in the production of Aβ amyloid peptides. It cleaves the transmembrane domain of the amyloid precursor protein (APP at alternative sites to produce Aβ and the APP intracellular domain (AICD. Metal ions play an important role in Aβ aggregation and metabolism, thus metal chelators and ligands represent potential therapeutic agents for AD treatment. A direct effect of metal chelators on γ-secretase has not yet been investigated. The authors used an in vitro  γ-secretase assay consisting of cleavage of APP C100-3XFLAG by endogenous γ-secretase from rodent brains and human neuroblastoma SH-SY5Y, and detected AICD production by western blotting. Adding metalloprotease inhibitors to the reaction showed that clioquinol, phosphoramidon, and zinc metalloprotease inhibitors had no significant effect on γ-secretase activity. In contrast, phenanthroline, EDTA, and EGTA markedly decreased γ-secretase activity that could be restored by adding back calcium and magnesium ions. Mg2+ stabilized a 1,000 kDa presenilin 1 complex through blue native gel electrophoresis and size-exclusion chromatography. Data suggest that Ca2+ and Mg2+ stabilize γ-secretase and enhance its activity.

  19. MS characterization of some metallocene dithiolene chelate complexes of the early transition metals - first synthesis of vanadocene toluene-3,4-dithiolate

    International Nuclear Information System (INIS)

    Klapoetke, T.; Koepf, H.

    1988-01-01

    Fragmentation patterns (under the conditions in the mass spectrometer) of the metallocene dithiolene chelate complexes of some early transition metals (subgroup IV-VI) were investigated. In some cases ion geneses could be elucidated by purchasing metastable transitions, using the linked scan technique. After cleavage of one cyclopentadienyl ring the unsubstituted ethene dithiolates surprisingly show an intense peak corresponding to an elimination of acetylene as a neutral particle, which contrasts to the analogous maleonitrile derivatives. The first synthesis of Cp 2 V(1,2-S 2 C 6 H 3 CH 3 -4) (Cp = C 5 H 5 ) is described. (author)

  20. Light-Induced Copper(II) Coordination by a Bicyclic Tetraaza Chelator through a Ligand-to-Metal Charge-Transfer Reaction

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Jacob Rørdam; Jensen, Mikael; Bjerrum, Morten J.

    2011-01-01

    To enable utilization of the broad potential of copper isotopes in nuclear medicine, rapid and robust chelation of the copper is required. Bowl adamanzanes (bicyclic tetraaza ligands) can form kinetically stable copper complexes, but they are usually formed at low rates unless high pH values...... coordinated amine groups) at pH above 6. These findings are supported by pH titrations of mixtures of Cu2+ and [24.31]adz in water. Irradiation of this complex in the ligand-to-metal charge-transfer (LMCT) band by a diode-array spectrophotometer leads to photodeprotonation and subsequently to formation...

  1. Synthesis and coordination chemistry of two N2-donor chelating di(indazolyl)methane ligands: structural characterization and comparison of their metal chelation aptitudes.

    Science.gov (United States)

    Pettinari, Claudio; Marinelli, Alessandro; Marchetti, Fabio; Ngoune, Jean; Galindo, Agustín; Álvarez, Eleuterio; Gómez, Margarita

    2010-11-15

    The N(2)-donor bidentate ligands di(1H-indazol-1-yl)methane (L(1)) and di(2H-indazol-2-yl)methane (L(2)) (L in general) have been synthesized, and their coordination behavior toward Zn(II), Cd(II), and Hg(II) salts has been studied. Reaction of L(1) and L(2) with ZnX(2) (X = Cl, Br, or I) yields [ZnX(2)L] species (1-6), that, in the solid state, show a tetrahedral structure with dihapto ligand coordination via the pyrazolyl arms. The reaction of L(1) and L(2) with Zn(NO(3))(2)·6H(2)O is strongly dependent on the reaction conditions and on the ligand employed. Reaction of L(1) with equimolar quantities of Zn(NO(3))(2)·6H(2)O yields the neutral six-coordinate species [Zn(NO(3))(2)(L(1))], 7. On the other hand the use of L(1) excess gives the 2:1 adduct [Zn(NO(3))(2)(L(1))(2)], 8 where both nitrates act as a unidentate coordinating ligand. Analogous stoichiometry is found in the compound obtained from the reaction of L(2) with Zn(NO(3))(2)·6H(2)O which gives the ionic [Zn(NO(3))(L(2))(2)](NO(3)), 10. Complete displacement of both nitrates from the zinc coordination sphere is observed when the reaction between L(1) excess and the zinc salt was carried out in hydrothermal conditions. The metal ion type is also determining structure and stoichiometry: the reaction of L(2) with CdCl(2) gave the 2:1 adduct [CdCl(2)(L(2))(2)] 11 where both chlorides complete the coordination sphere of the six-coordinate cadmium center; on the other hand from the reaction of L(1) with CdBr(2) the polynuclear [CdBr(2)(L(1))](n) 12 is obtained, the Br(-) anion acting as bridging ligands in a six-coordinate cadmium coordination environment. The reaction of L(1) and L(2) with HgX(2) (X = Cl, I, SCN) is also dependent on the reaction conditions and the nature of X, two different types of adducts being formed [HgX(L)] (14: L = L(1), 16, 17: L = L(1) or L(2), X = I, 19: L = L(2), X = SCN) and [HgX(L)(2)] (15: L = L(2), X = Cl, 18: L = L(1), X = SCN). The X-ray diffraction analyses of compounds 1

  2. A new morphological approach for removing acid dye from leather waste water: preparation and characterization of metal-chelated spherical particulated membranes (SPMs).

    Science.gov (United States)

    Şenay, Raziye Hilal; Gökalp, Safiye Meriç; Türker, Evren; Feyzioğlu, Esra; Aslan, Ahmet; Akgöl, Sinan

    2015-03-15

    In this study, p(HEMA-GMA) poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) spherical particulated membranes (SPMs) were produced by UV-photopolymerization and the synthesized SPMs were coupled with iminodiacetic acid (IDA). Finally the novel SPMs were chelated with Cr(III) ions as ligand and used for removing acid black 210 dye. Characterizations of the metal-chelated SPMs were made by SEM, FTIR and swelling test. The water absorption capacities and acid dye adsorption properties of the SPMs were investigated and the results were 245.0, 50.0, 55.0 and 51.9% for p(HEMA), p(HEMA-GMA), p(HEMA-GMA)-IDA and p(HEMA-GMA)-IDA-Cr(III) SPMs respectively. Adsorption properties of the p(HEMA-GMA)-IDA-Cr(III) SPMs were investigated under different conditions such as different initial dye concentrations and pH. The optimum pH was observed at 4.3 and the maximum adsorption capacity was determined as 885.14 mg/g at about 8000 ppm initial dye concentration. The concentrations of the dyes were determined using a UV/Vis Spectrophotometer at a wavelength of 435 nm. Reusability of p(HEMA-GMA)-IDA-Cr(III) SPMs was also shown for five adsorption-desorption cycles without considerable decrease in its adsorption capacity. Finally, the results showed that the metal-chelated p(HEMA-GMA)-IDA SPMs were effective sorbent systems removing acid dye from leather waste water. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. 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.

  4. 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.

  5. Hydroxypyridinonate complex stability of group (IV) metals and tetravalent f-block elements: the key to the next generation of chelating agents for radiopharmaceuticals.

    Science.gov (United States)

    Sturzbecher-Hoehne, Manuel; Choi, Taylor A; Abergel, Rebecca J

    2015-04-06

    The solution thermodynamics of the water-soluble complexes formed between 3,4,3-LI(1,2-HOPO) and Zr(IV) or Pu(IV) were investigated to establish the metal coordination properties of this octadentate chelating agent. Stability constants log β110 = 43.1 ± 0.6 and 43.5 ± 0.7 were determined for [Zr(IV)(3,4,3-LI(1,2-HOPO))] and [Pu(IV)(3,4,3-LI(1,2-HOPO))], respectively, by spectrophotometric competition titrations against Ce(IV). Such high thermodynamic stabilities not only confirm the unparalleled Pu(IV) affinity of 3,4,3-LI(1,2-HOPO) as a decorporation agent but also corroborate the great potential of hydroxypyridinonate ligands as new (89)Zr-chelating platforms for immuno-PET applications. These experimental values are in excellent agreement with previous estimates and are discussed with respect to ionic radius and electronic configuration, in comparison with those of Ce(IV) and Th(IV). Furthermore, a liquid chromatography assay combined with mass spectrometric detection was developed to probe the separation of the neutral [M(IV)(3,4,3-LI(1,2-HOPO))] complex species (M = Zr, Ce, Th, and Pu), providing additional insight into the coordination differences between group IV and tetravalent f-block metals and on the role of d and f orbitals in bonding interactions.

  6. Chelated minerals for poultry

    Directory of Open Access Journals (Sweden)

    SL Vieira

    2008-06-01

    Full Text Available Organic minerals have been subject of an increasing number of investigations recently. These compounds can be considered the most significant event regarding commercial forms of minerals targeting animal supplementation in the last decades. Minerals, especially metals, are usually supplemented in poultry feeds using cheap saline sources and have never required a lot of attention in terms of quality. On the other hand, definitions of organic minerals are very broad and frequently lead to confusion when decision-making becomes necessary. Organic minerals include any mineral bound to organic compounds, regardless of the type of existing bond between mineral and organic molecules. Proteins and carbohydrates are the most frequent candidates in organic mineral combinations. Organic fraction size and bond type are not limitations in organic mineral definition; however, essential metals (Cu, Fe, Zn, and Mn can form coordinated bonds, which are stable in intestinal lumen. Metals bound to organic ligands by coordinated bonds can dissociate within animal metabolism whereas real covalent bonds cannot. Chelated minerals are molecules that have a metal bound to an organic ligand through coordinated bonds; but many organic minerals are not chelates or are not even bound through coordinated bonds. Utilization of organic minerals is largely dependent on the ligand; therefore, amino acids and other small molecules with facilitated access to the enterocyte are supposed to be better utilized by animals. Organic minerals with ligands presenting long chains may require digestion prior to absorption. After absorption, organic minerals may present physiological effects, which improve specific metabolic responses, such as the immune response. Many studies have demonstrated the benefits of metal-amino acid chelates on animal metabolism, but the detection positive effects on live performance is less consistent.

  7. 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.

  8. Purification of monoclonal antibodies, IgG1, from cell culture supernatant by use of metal chelate convective interaction media monolithic columns.

    Science.gov (United States)

    Rajak, Poonam; Vijayalakshmi, M A; Jayaprakash, N S

    2012-12-01

    Monoclonal antibodies (MAbs) have diverse applications in diagnostics and therapeutics. The recent advancement in hybridoma technology for large-scale production of MAbs in bioreactors demands rapid and efficient purification methods. Conventional affinity purification systems have drawbacks of low flow rates and denaturation of antibodies owing to harsh elution conditions. Here, we attempted purification of MAbs by use of a high-throughput metal-chelate methacrylate monolithic system. Monolithic macroporous convective interaction media-iminodiacetate (CIM-IDA) disks immobilized with four different metal ions (Cu²⁺, Ni²⁺, Zn²⁺ and Co²⁺) were used and evaluated for purification of anti-human serum albumin IgG1 mouse MAbs from cell culture supernatant after precipitation with 50% ammonium sulfate. Elution with 10 mM imidazole in the equilibration buffer (25 mM MMA = MOPS (Morpholino propane sulfonic acid) + MES (Morpholino ethane sulfonic acid) + Acetate + 0.5 M NaCl, pH 7.4) resulted in a purification of 25.7 ± 2.9-fold and 32.5 ± 2.6-fold in experiments done using Zn²⁺ and Co²⁺ metal ions, respectively. The highest recovery of 85.4 ± 1.0% was obtained with a CIM-IDA-Zn(II) column. SDS-PAGE, ELISA and immuno-blot showed that the antibodies recovered were pure, with high antigen-binding efficiency. Thus, metal chelate CIM monoliths could be a potential alternative to conventional systems for fast and efficient purification of MAbs from the complex cell culture supernatant. Copyright © 2012 John Wiley & Sons, Ltd.

  9. Molar absorption coefficients and stability constants of metal complexes of 4-(2-pyridylazo)resorcinol (PAR): Revisiting common chelating probe for the study of metalloproteins.

    Science.gov (United States)

    Kocyła, Anna; Pomorski, Adam; Krężel, Artur

    2015-11-01

    4-(2-Pyridylazo)resorcinol (PAR) is one of the most popular chromogenic chelator used in the determination of the concentrations of various metal ions from the d, p and f blocks and their affinities for metal ion-binding biomolecules. The most important characteristics of such a sensor are the molar absorption coefficient and the metal-ligand complex dissociation constant. However, it must be remembered that these values are dependent on the specific experimental conditions (e.g. pH, solvent components, and reactant ratios). If one uses these values to process data obtained in different conditions, the final result can be under- or overestimated. We aimed to establish the spectral properties and the stability of PAR and its complexes accurately with Zn(2+), Cd(2+), Hg(2+), Co(2+), Ni(2+), Cu(2+), Mn(2+) and Pb(2+) at a multiple pH values. The obtained results account for the presence of different species of metal-PAR complexes in the physiological pH range of 5 to 8 and have been frequently neglected in previous studies. The effective molar absorption coefficient at 492 nm for the ZnHx(PAR)2 complex at pH7.4 in buffered water solution is 71,500 M(-1) cm(-1), and the dissociation constant of the complex in these conditions is 7.08×10(-13) M(2). To confirm these values and estimate the range of the dissociation constants of zinc-binding biomolecules that can be measured using PAR, we performed several titrations of zinc finger peptides and zinc chelators. Taken together, our results provide the updated parameters that are applicable to any experiment conducted using inexpensive and commercially available PAR. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Critical evaluation of equilibrium constants involving 8-hydroxyquinoline and its metal chelates critical evaluation of equilibrium constants in solution : part b : equilibrium constants of liquid-liquid distribution systems

    CERN Document Server

    Stary, J

    1979-01-01

    Critical Evaluation of Equilibrium Constants Involving 8-Hydroxyquinoline and Its Metal Chelates presents and evaluates the published data on the solubility, dissociation, and liquid-liquid distribution of oxine and its metal chelates to recommend the most reliable numerical data. This book explores the dissociation constants of oxine in aqueous solutions.Organized into four chapters, this book begins with an overview of the characteristics of 8-hydroxyquinoline (oxine). This text then examines the total solubility of oxine in aqueous solution at different pH values. Other chapters consider th

  11. Diamidophosphines with six-membered chelates and their coordination chemistry with group 4 metals: development of a trimethylene-methane-tethered [PN2]-type "molecular claw".

    Science.gov (United States)

    Batke, S; Kothe, T; Haas, M; Wadepohl, H; Ballmann, J

    2016-02-28

    The coordination chemistry of the phosphine-tethered diamidophosphine ligands PhP(CH2CH2CH2NHPh)2 (pr[NPN]H2) and PhP(1,2-CH2-C6H4-NHSiMe3)2 (bn[NPN]H2) featuring six-membered N–C3–P chelates was explored with group 4 metals, which allowed for the consecutive development of a new trimethylene-methane-tethered [PN2] scaffold. In the case of the propylene-linked system pr[NPN]H2, access to the sparingly soluble dibenzyl derivative pr[NPN]ZrBn2 (3-Zr) was gained, while thermally sensitive zirconium and hafnium diiodo complexes bn[NPN]MI2 (5-M, M = Zr, Hf) were isolated in the case of the benzylene-linked derivative bn[NPN]H2. Despite the related phosphine-tethered backbone architectures of both of these ligands, their group 4 complexes were found to exhibit either C1-symmetric (bn[NPN]MX2) or averaged CS-symmetric (pr[NPN]MX2) structures in solution. To restrain the overall flexibility of these systems and thereby control the properties of the resulting complexes without disrupting the six-membered chelates, the new trimethylene-methane-tethered N,N′-di-(tert-butyl)-substituted [PN2]H2 protioligand was designed. This tripodal ligand system was prepared on a gram scale and its CS-symmetric dichloro complexes [PN2]MCl2 (6-M, M = Ti, Zr, Hf) were isolated subsequently. The benzene-soluble dibenzyl derivative [PN2]ZrBn2 (7-Zr) was synthesised as well and characterised by X-ray diffraction. These results are discussed not only in conjunction with the known [NPN]-coordinated group 4 complexes incorporating five-membered chelates, but also in the context of “molecular claws” that are related to the new [PN2] tripod.

  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. Metal chelator EGCG attenuates Fe(III)-induced conformational transition of α-synuclein and protects AS-PC12 cells against Fe(III)-induced death.

    Science.gov (United States)

    Zhao, Juan; Xu, Lihui; Liang, Qingnan; Sun, Qing; Chen, Congheng; Zhang, Yuan; Ding, Yu; Zhou, Ping

    2017-10-01

    The fibrillation and aggregation of α-synuclein (AS), along with the conformational transition from random coil to β-sheet, are the critical steps in the development of Parkinson's disease (PD). It is acknowledged that iron accumulation in the brain may lead to the fibrillation of AS. However, (-)-epigallocatechin gallate (EGCG) can penetrate the blood-brain barrier, chelate metal ions, and inhibit the fibrillation of amyloid proteins. Therefore, EGCG is warranted to be investigated for its potential to cure amyloid-related diseases. In the present work, we sought to study the effects of EGCG on Fe(III)-induced fibrillation of AS on both molecular and cellular levels. We demonstrate that Fe(III) interacts with the amino residue of Tyr and Ala of AS, then accelerates the fibrillation of AS, and increases intracellular reactive oxygen species (ROS) in the AS transduced-PC12 cells (AS-PC12 cells). However, EGCG significantly inhibits this process by chelating Fe(III) and protects AS-PC12 cells against the toxicity induced by ROS and β-sheet-enriched AS fibrils. These findings yield useful information that EGCG might be a promising drug to prevent and treat the neurodegenerative diseases. © 2017 International Society for Neurochemistry.

  14. Quercetin inhibits advanced glycation end product formation via chelating metal ions, trapping methylglyoxal, and trapping reactive oxygen species.

    Science.gov (United States)

    Bhuiyan, Mohammad Nazrul Islam; Mitsuhashi, Shinya; Sigetomi, Kengo; Ubukata, Makoto

    2017-05-01

    Physiological concentration of Mg 2+ , Cu 2+ , and Zn 2+ accelerated AGE formation only in glucose-mediated conditions, which was effectively inhibited by chelating ligands. Only quercetin (10) inhibited MGO-mediated AGE formation as well as glucose- and ribose-mediated AGE formation among 10 polyphenols (1-10) tested. We performed an additional structure-activity relationship (SAR) study on flavanols (10, 11, 12, 13, and 14). Morin (12) and kaempherol (14) showed inhibitory activity against MGO-mediated AGE formation, whereas rutin (11) and fisetin (13) did not. These observations indicate that 3,5,7,4'-tetrahydroxy and 4-keto groups of 10 are important to yield newly revised mono-MGO adducts (16 and 17) and di-MGO adduct (18) having cyclic hemiacetals, while 3'-hydroxy group is not essential. We propose here a comprehensive inhibitory mechanism of 10 against AGE formation including chelation effect, trapping of MGO, and trapping of reactive oxygen species (ROS), which leads to oxidative degradation of 18 to 3,4-dihydroxybenzoic acid (15) and other fragments.

  15. Metal Chelation Assisted In Situ Migration and Functionalization of Catalysts on Peapod-Like Hollow SnO2toward a Superior Chemical Sensor.

    Science.gov (United States)

    Jang, Ji-Soo; Yu, Sunmoon; Choi, Seon-Jin; Kim, Sang-Joon; Koo, Won-Tae; Kim, Il-Doo

    2016-11-01

    Rational design of nanostructures and efficient catalyst functionalization methods are critical to the realization of highly sensitive gas sensors. In order to solve these issues, two types of strategies are reported, i.e., (i) synthesis of peapod-like hollow SnO 2 nanostructures (hollow 0D-1D SnO 2 ) by using fluid dynamics of liquid Sn metal and (ii) metal-protein chelate driven uniform catalyst functionalization. The hollow 0D-1D SnO 2 nanostructures have advantages in enhanced gas accessibility and higher surface areas. In addition to structural benefits, protein encapsulated catalytic nanoparticles result in the uniform catalyst functionalization on both hollow SnO 2 spheres and SnO 2 nanotubes due to their dynamic migration properties. The migration of catalysts with liquid Sn metal is induced by selective location of catalysts around Sn. On the basis of these structural and uniform functionalization of catalyst benefits, biomarker chemical sensors are developed, which deliver highly selective detection capability toward acetone and toluene, respectively. Pt or Pd loaded multidimensional SnO 2 nanostructures exhibit outstanding acetone (R air /R gas = 93.55 @ 350 °C, 5 ppm) and toluene (R air /R gas = 9.25 @ 350 °C, 5 ppm) sensing properties, respectively. These results demonstrate that unique nanostructuring and novel catalyst loading method enable sensors to selectively detect biomarkers for exhaled breath sensors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. 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)

  17. Hydration of amphiphilic metal chelates in aqueous solutions and its effect on partition equilibria in solvent extraction

    International Nuclear Information System (INIS)

    Narbutt, J.

    2001-01-01

    In this paper author deals with hydration of metal complexes formed in aqueous solution significantly affects their distribution (partition) between the aqueous and organic phase. Three kinds of hydration: hydrophobic hydration of lipophilic fragments of ligands, inner-sphere hydration, i.e. coordination of water molecules in the inner-sphere of the central metal ion, and outer-sphere hydration, as well as other factor influenced of extraction are reviewed

  18. Enhanced Retention of Chelating Reagents in Octadecylsilyl Silica Phase by Interaction with Residual Silanol Groups in Solid Phase Extraction of Divalent Metal Ions.

    Science.gov (United States)

    Ohmuro, Satoshi; Fujii, Kan; Yasui, Takashi; Takada, Kazutake; Yuchi, Akio; Kokusen, Hisao

    2016-01-01

    Solid-phase extraction (SPE) of divalent metal ions with a lipophilic and potentially divalent hexadentate chelating reagent (H2L), with which octadecylsilyl silica (ODS), was impregnated with was studied to gain more insight into and develop the potential of this methodology. This is the first time to demonstrate that this reagent as well as other common nitrogen-containing reagents were retained both by adsorption due to hydrogen bonding between nitrogen atoms of the reagent and residual silanol groups in the ODS phase and by simple distribution into the hydrophobic space. An appreciably large amount of this reagent could be retained by the adsorption mechanism even with a relatively thin loading solution. The divalent metal ions of Mn(2+), Co(2+) and Zn(2+) were extracted as 1:1 neutral complexes ([ML]), while Ni(2+) and Cu(2+) as ion-pairs of 1:1 cationic complex ([MHL](+)) with anion in SPE with H2L. The extractability and selectivity were substantially the same as that in liquid-liquid extraction.

  19. Uranyl chelate lasers, realization

    International Nuclear Information System (INIS)

    Macheteau, Y.; Coste, A.; Luce, M.; Rigny, P.

    1975-01-01

    The absorption fluorescence and excitation spectra of uranyle chelates were determined. The corresponding fluorescence decay was measured at low temperature. The possibility of obtaining a stimulated emission with uranyl chelates is examined from the consideration made on the properties of Eu chelates (B 4 EuNa and B 4 Eu piperidine) which give the laser effect [fr

  20. 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.

  1. 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

  2. Compression and immersion tests and leaching of radionuclides, stable metals, and chelating agents from cement-solidified decontamination waste collected from nuclear power stations

    International Nuclear Information System (INIS)

    Akers, D.W.; Kraft, N.C.; Mandler, J.W.

    1994-06-01

    A study was performed for the Nuclear Regulatory Commission (NRC) to evaluate structural stability and leachability of radionuclides, stable metals, and chelating agents from cement-solidified decontamination ion-exchange resin wastes collected from seven commercial boiling water reactors and one pressurized water reactor. The decontamination methods used at the reactors were the Can-Decon, AP/Citrox, Dow NS-1, and LOMI processes. Samples of untreated resin waste and solidified waste forms were subjected to immersion and compressive strength testing. Some waste-form samples were leach-tested using simulated groundwaters and simulated seawater for comparison with the deionized water tests that are normally performed to assess waste-form leachability. This report presents the results of these tests and assesses the effects of the various decontamination methods, waste form formulations, leachant chemical compositions, and pH of the leachant on the structural stability and leachability of the waste forms. Results indicate that releases from intact and degraded waste forms are similar and that the behavior of some radionuclides such as 55 Fe, 60 Co, and 99 Tc were similar. In addition, the leachability indexes are greater than 6.0, which meets the requirement in the NRC's ''Technical Position on Waste Form,'' Revision 1

  3. Compression and immersion tests and leaching of radionuclides, stable metals, and chelating agents from cement-solidified decontamination waste collected from nuclear power stations

    Energy Technology Data Exchange (ETDEWEB)

    Akers, D.W.; Kraft, N.C.; Mandler, J.W. [EG and G Idaho, Inc., Idaho Falls, ID (United States)

    1994-06-01

    A study was performed for the Nuclear Regulatory Commission (NRC) to evaluate structural stability and leachability of radionuclides, stable metals, and chelating agents from cement-solidified decontamination ion-exchange resin wastes collected from seven commercial boiling water reactors and one pressurized water reactor. The decontamination methods used at the reactors were the Can-Decon, AP/Citrox, Dow NS-1, and LOMI processes. Samples of untreated resin waste and solidified waste forms were subjected to immersion and compressive strength testing. Some waste-form samples were leach-tested using simulated groundwaters and simulated seawater for comparison with the deionized water tests that are normally performed to assess waste-form leachability. This report presents the results of these tests and assesses the effects of the various decontamination methods, waste form formulations, leachant chemical compositions, and pH of the leachant on the structural stability and leachability of the waste forms. Results indicate that releases from intact and degraded waste forms are similar and that the behavior of some radionuclides such as {sup 55}Fe, {sup 60}Co, and {sup 99}Tc were similar. In addition, the leachability indexes are greater than 6.0, which meets the requirement in the NRC`s ``Technical Position on Waste Form,`` Revision 1.

  4. Preconcentration and determination of trace metal ions from aqueous samples by newly developed gallic acid modified Amberlite XAD-16 chelating resin.

    Science.gov (United States)

    Sharma, R K; Pant, Parul

    2009-04-15

    Gallic acid was immobilized on Amberlite XAD-16 by coupling it through -N=N group. The resulting chelating resin Amberlite XAD-16 gallic acid, characterized by thermogravimetric analysis (TGA), infrared (IR) spectra and BET analysis, was used to preconcentrate Cr(III), Mn(II),Fe(III),Co(II), Ni(II) and Cu(II)ions. The resin was employed for the preconcentration of the metal ions present in river water and industrial area aqueous samples. Several parameters like effect of pH, effect of time, effect of sample volume and flow rate of sample were investigated. The sorption capacities for the resin were 216 micromol g(-1), 180 micromol g(-1), 403 micromol g(-1), 281 micromol g(-1), 250 micromol g(-1) and 344 micromol g(-1) for Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) respectively. The preconcentration factors for Cr(III), Mn(II), Fe(III), Ni(II), Co(II) and Cu(II) were found out to be 300, 200, 400, 285.7, 300 and 400 respectively. The effect of various interfering ions was also studied. Results were validated by using standard addition method for river water sample.

  5. On the Anticataractogenic Effects of L-Carnosine: Is It Best Described as an Antioxidant, Metal-Chelating Agent or Glycation Inhibitor?

    Directory of Open Access Journals (Sweden)

    Hamdy Abdelkader

    2016-01-01

    Full Text Available Purpose. L-Carnosine is a naturally occurring dipeptide which recently gained popularity as an anticataractogenic agent due to its purported antioxidant activities. There is a paucity of research and conclusive evidence to support such claims. This work offers compelling data that help clarify the mechanism(s behind the anticataract properties of L-carnosine. Methods. Direct in vitro antioxidant free radical scavenging properties were assayed using three different antioxidant (TEAC, CUPRAC, and DPPH assays. Indirect in vitro and ex vivo antioxidant assays were studied by measuring glutathione bleaching capacity and total sulfhydryl (SH capacity of bovine lens homogenates as well as hydrogen-peroxide-stress assay using human lens epithelial cells. Whole porcine lenses were incubated in high galactose media to study the anticataract effects of L-carnosine. MTT cytotoxicity assays were conducted on human lens epithelial cells. Results. The results showed that L-carnosine is a highly potent antiglycating agent but with weak metal chelating and antioxidant properties. There were no significant decreases in lens epithelial cell viability compared to negative controls. Whole porcine lenses incubated in high galactose media and treated with 20 mM L-carnosine showed a dramatic inhibition of advanced glycation end product formation as evidenced by NBT and boronate affinity chromatography assays. Conclusion. L-Carnosine offers prospects for investigating new methods of treatment for diabetic cataract and any diseases that are caused by glycation.

  6. Coordination of two high-affinity hexamer peptides to copper(II) and palladium(II) models of the peptide-metal chelation site on IMAC resins

    Energy Technology Data Exchange (ETDEWEB)

    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){sub 6} (HHHHHH) to [Pd{sup II}(mida)(D{sub 2}O)] (mida{sup 2{minus}} = N-methyliminodiacetate) was studied by {sup 1}H NMR as model reactions for Cu{sup II}(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 H{sub 1}, H{sub 3}, and H{sub 4} of (His){sub 6} and H{sub 3} and H{sub 4} of SPHHGG was detected by {sup 1}H NMR contact shifts and H/D exchange of histidyl protons. The EPR spectra of SPHHGG and HHHHHH attached to the [Cu{sup II}(mida)] unit were obtained for additional modeling of IMAC sites. EPR parameters of the parent [Cu(mida)(H{sub 2}O){sub 2}] complex are representative: g{sub zz} = 2.31; g{sub yy} = 2.086; g{sub xx} = 2.053; A{sub {vert_bar}{vert_bar}} = 161 G; A{sub N} = 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 > (H{sub 2}O){sub 2}. The lowering of symmetry is also seen in the decrease in the N-shf coupling, presumably to the imino nitrogen of mida{sup 2{minus}} in the order 19 G (H{sub 2}O), 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 [Pd{sup II}(mida)L] derivatives which form the two-chelate

  7. Preconcentration/separation of some trace metal ions from water samples by a new synthesized chelating resin.

    Science.gov (United States)

    Sener, Seher; Tokalioğlu, Serife; Ozentürk, Ismail; Soykan, Cengiz

    2014-01-01

    A solid phase extractor, poly(N,N'-dipropionitrile methacrylamide-co-divinylbenzene-co-2-acrylamido-2-methyl-1-propanesulfonic acid), was synthesized and used for separation/preconcentration of traces of Ni(II), Co(II), Cu(II), Mn(II), Cd(II), Zn(II), and Pb(II) from various water samples prior to their determination by flame atomic absorption spectrometry. The characterization of the synthesized resin was performed by elemental analysis and IR spectrometry. Parameters such as pH, volume and concentration of the eluent, flow rate of the sample solution, sample volume, and interfering ions affecting the column SPE were examined. The optimum pH was found to be 3. The retained metal ions were desorbed from the column with 10 mL of 1 M HCI eluent. A high preconcentration factor, 40-100; low RSD, method was confirmed by analyzing certified reference materials (TMDA-70 Lake Water and SPS-WW1 Batch 111-Wastewater) and spiked water samples. The method was successfully applied to the determination of metal ions in tap, lake, and dam waters.

  8. 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.)

  9. Evaluation of copper speciation in model solutions of humic acid by mini-columns packed with Chelex-100 and new chelating agents: Application to speciation of selected heavy metals in environmental water samples

    International Nuclear Information System (INIS)

    Kiptoo, Jackson K.; Ngila, J. Catherine; Silavwe, Ned D.

    2009-01-01

    A solid-phase extraction procedure using mini-columns packed with Chelex-100 and two new chelating agents based on poly(vinyl chloride) functionalized with 3-ferrocenyl-3-hydroxydithioacrylic acid and N,N'-[1,1'-dithiobis(ethylene)]-bis(salicylideneimine) (H 2 sales) loaded on microcrystalline naphthalene, is reported. The columns were used to separate labile copper fractions in model solutions and in real samples with subsequent determination using electrothermal atomic absorption spectrometry (ETAAS). Various model solutions containing 20 μg L -1 of Cu 2+ and 0.0, 0.2, 2.0 and 20.0 mg L -1 of humic acid, respectively, and buffered to pH 6.0, 7.0 and 8.0 were considered. Results showed a decrease in labile copper fraction with increase in humic acid concentration. Application of the procedure to speciation of Cu, Ni, Zn and Pb in various environmental water samples yielded labile fractions in the range of 1.67-55.75% against a total dissolved fraction of 44.08-69.77%. Comparison of the three chelating agents showed that H 2 sales had a weaker metal chelating strength than Chelex-100, but PVC-FSSH had comparable chelating strength to Chelex-100.

  10. Evaluation of copper speciation in model solutions of humic acid by mini-columns packed with Chelex-100 and new chelating agents: Application to speciation of selected heavy metals in environmental water samples

    Energy Technology Data Exchange (ETDEWEB)

    Kiptoo, Jackson K., E-mail: kiptoojac@yahoo.com [Department of Chemistry, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi (Kenya); Ngila, J. Catherine [School of Chemistry, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Westville, Durban 4000 (South Africa); Silavwe, Ned D. [Department of Chemistry, University of Swaziland, P/Bag 4, Kwaluseni (Swaziland)

    2009-12-30

    A solid-phase extraction procedure using mini-columns packed with Chelex-100 and two new chelating agents based on poly(vinyl chloride) functionalized with 3-ferrocenyl-3-hydroxydithioacrylic acid and N,N'-[1,1'-dithiobis(ethylene)]-bis(salicylideneimine) (H{sub 2}sales) loaded on microcrystalline naphthalene, is reported. The columns were used to separate labile copper fractions in model solutions and in real samples with subsequent determination using electrothermal atomic absorption spectrometry (ETAAS). Various model solutions containing 20 {mu}g L{sup -1} of Cu{sup 2+} and 0.0, 0.2, 2.0 and 20.0 mg L{sup -1} of humic acid, respectively, and buffered to pH 6.0, 7.0 and 8.0 were considered. Results showed a decrease in labile copper fraction with increase in humic acid concentration. Application of the procedure to speciation of Cu, Ni, Zn and Pb in various environmental water samples yielded labile fractions in the range of 1.67-55.75% against a total dissolved fraction of 44.08-69.77%. Comparison of the three chelating agents showed that H{sub 2}sales had a weaker metal chelating strength than Chelex-100, but PVC-FSSH had comparable chelating strength to Chelex-100.

  11. 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

  12. Suppression of survival in human SKBR3 breast carcinoma in response to metal-chelator complexes is preferential for copper-dithiocarbamate.

    Science.gov (United States)

    Viola-Rhenals, Maricela; Rieber, Mary Strasberg; Rieber, Manuel

    2006-03-14

    Since diethyl dithiocarbamate (DEDTC) forms complexes with either zinc or copper, and 8-hydroxyquinoline (8-OHQ) also complexes with copper, we now compared the cytotoxic activity of Cu[DEDTC]2, Zn[DEDTC]2 and Cu[8-OHQ]2. This report shows that at nanomolar levels, only copper-[DEDTC]2, suppresses proliferation and clonogenicity of SKBR3 human breast carcinoma, concurrently with induction of apoptosis-associated PARP fragmentation. Susceptibility to these agents was paralleled by reactive oxygen generation (ROS) and greater expression of anti-oxidant enzymes like MnSOD and catalase, with no comparable effect on Cu/Zn superoxide dismutase. The lethal effects of Cu[DEDTC]2 manifested when adding the two separate aqueous components or the preformed synthetic complexes in DMSO, was prevented by N-acetyl cysteine or glutathione, with no comparable protection afforded by non-thiol anti-oxidants like mannitol or DMSO. Exogenously added catalase also protected cells from Cu[DEDTC]2, suggesting that this complex may kill after the levels of superoxide anion [O2*-] dismutated by MnSOD increase hydrogen peroxide-related stress. Cu[DEDTC]2 also induced p21WAF1, a cdk inhibitor usually not inducible in mutant p53 tumors like SKBR3 carcinoma, correlating with dephosphorylation of the Sp1 transcription factor. Concentrations of Cu[DEDTC]2 cytotoxic for SKBR3 carcinoma did not induce comparable damage versus normal diploid human WI-38 fibroblasts. In contrast to the cytotoxic effect of nM levels of Cu[DEDTC]2 against SKBRR3 cells, no response was seen in the same cells exposed to 20 microM cis-platin. Since neither DEDTC bound to zinc, nor copper bound to 8-OHQ showed comparable cytotoxicity, our results suggest that the greater activity of copper-DEDTC reflects a specific structure-activity relationship for the active complex. Since Cu[DEDTC]2 shows more effectiveness than other metal-chelator complexes, it may be worth further investigation as an alternative to cancer therapies.

  13. Solid-phase extraction and determination of trace amount of some metal ions on Duolite XAD 761 modified with a new Schiff base as chelating agent in some food samples.

    Science.gov (United States)

    Marahel, F; Ghaedi, M; Montazerozohori, M; Biyareh, M Nejati; Kokhdan, S Nasiri; Soylak, M

    2011-01-01

    A method for preconcentration of trace heavy metal ions in environmental samples has been reported. The presented method is based on the sorption of Cr(3+), Co(2+), Cu(2+), Fe(3+), Ni(2+), and Zn(2+) ions with 2-(2,4-dichlorobenzylideneamino) benzenethiol as respective chelate on modified Duolite XAD 761. The metals content of the sorbed complexes are eluted using 6 ml of 4M nitric acid. The influences of the analytical parameters including pH, amount of ligand and solid phase and condition of eluting solution, the effects of matrix ions on the retentions of the analytes were examined. The recoveries of analytes are generally higher than 94% and the RSD is between 1.5% and 2.2%. The method has been successfully applied for the evaluation of understudy metals content in some food samples. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Inhibition of warfarin anticoagulation associated with chelation therapy.

    Science.gov (United States)

    Grebe, Heidi Braun; Gregory, Philip J

    2002-08-01

    Chelation therapy originally was administered exclusively to patients with heavy metal poisoning. Now some physicians are administering this therapy for numerous conditions, most commonly coronary heart disease. A 64-year-old man experienced impaired warfarin anticoagulation after undergoing chelation therapy His international normalized ratio (INR) fell from 2.6 the day before to 1.6 the day after therapy was administered. Whether chelation therapy decreases the effectiveness of warfarin anticoagulation is uncertain. However, because of this potential interaction, clinicians should consider increased INR monitoring in patients undergoing chelation therapy.

  15. Chelates for Micronutrient Nutrition among Crops

    Indian Academy of Sciences (India)

    The three main classes of micronutrient sources are inorganic, synthetic chelates and organic complexes. Inorganic sources such as sulphates of Cu, Mn, Fe and Zn are the most common metallic salts used in the fertilizer industry because of their ready plant availability and water solubility. In the past 35-40 years, it has ...

  16. 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

  17. N,N',N"-tris(dihydroxyphosphorylmethyl)-1,4,7-triazacyclononane (Deofix) - a high-affinity, high-specificity chelator for first transition series metal cations with significant deodorant, antimicrobial, and antioxidant activity.

    Science.gov (United States)

    Laden, Karl; Zaklad, Haim; Simhon, Elliot D; Klein, Joseph Y; Cyjon, Rosa L; Winchell, Harry S

    2003-01-01

    Deofix, N,N',N"-tris(dihydroxyphosphorylmethyl)-1,4,7-triazacyclononane, is a high-affinity, high-specificity chelator for first transition series cations such as iron, zinc, manganese, and copper. A 1% solution in 50% ethanol was found to be significantly better at reducing underarm malodor than a solution of 0.3% Triclosan in 50% ethanol. Compared to a 50% alcohol control, Deofix was found to produce a significant reduction in malodor for at least 48 hours. Deofix appears to work by reducing the concentration of first transition series metal ions below the levels needed for microbial cell reproduction and by inhibiting oxidative processes by interfering with catalytic formation of free radicals. Deofix has very low levels of toxicity when measured via a number of screening techniques.

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

    OpenAIRE

    Johnson, Anthea; Singhal, Naresh

    2015-01-01

    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 phytoe...

  19. SYNTHESIS, CHARACTERIZATION AND ANTIFUNGAL ACTIVITY OF 2-[(8-HYDROXYQUINOLINYL-5-AMINOMETHYL]-3-(4-CHLOROPHENYL-6-BROMO-3(H-QUINAZOLIN-4-ONE LIGAND AND ITS TRANSITION METAL CHELATES

    Directory of Open Access Journals (Sweden)

    R. T. Vashi

    2015-07-01

    Full Text Available Synthesis and characterization of 2-[(8-hydroxyquinolinyl-5-aminomethyl]-3-(4-chlorophenyl-6-Bromo-3(H-quinazolin-4-one ligand called HAMQ (HL10 was studied. To prepare this ligand anthranilic acid was converted into 5-bromo–N-Chloroacetyl anthranilic acid then into 2-[(8-hydroxyquinolinyl -5-aminomethyl] -3-(4-chrolophenyl -6-bromo- 3(H-quinazolin-4-one. This compound was prepared by condensation with 5-amino-8-hydroxyquinoline. New transition metal chelates of Cu2+,Ni2+, Zn2+, Mn2+ and Co2+ of this ligand HAMQ  were  prepared and  characterized  by reflectance, 1H-NMR as well as IR spectroscopy, elemental analysis molar conductance and magnetic measurements. The stoichiometry of the complexes has been found to be 1: 2 (Metal: ligand. The data suggested an octahedral geometry around Co2+, Ni2+ and Mn2+ complexes, a distorted octahedral geometry around Cu2+ and a tetrahedral geometry around Zn2+ have been proposed. The metal complexes were screened for the antifungal activity.

  20. SYNTHESIS, CHARACTERIZATION AND ANTIFUNGAL ACTIVITY OF 2-[(8-HYDROXYQUINOLINYL-5-AMINOMETHYL]-3-(4-CHLOROPHENYL-6-BROMO-3(H-QUINAZOLIN-4-ONE LIGAND AND ITS TRANSITION METAL CHELATES

    Directory of Open Access Journals (Sweden)

    R. T. Vashi

    2013-12-01

    Full Text Available Synthesis and characterization of 2-[(8-hydroxyquinolinyl-5-aminomethyl]-3-(4-chlorophenyl-6-Bromo-3(H-quinazolin-4-one ligand called HAMQ (HL10 was studied. To prepare this ligand anthranilic acid was converted into 5-bromo–N-Chloroacetyl anthranilic acid then into 2-[(8-hydroxyquinolinyl -5-aminomethyl] -3-(4-chrolophenyl -6-bromo- 3(H-quinazolin-4-one. This compound was prepared by condensation with 5-amino-8-hydroxyquinoline. New transition metal chelates of Cu2+, Ni2+, Zn2+, Mn2+ and Co2+ of this ligand HAMQ were prepared and characterized by reflectance, 1H-NMR as well as IR spectroscopy, elemental analysis molar conductance and magnetic measurements. The stoichiometry of the complexes has been found to be 1: 2 (Metal: ligand. The data suggested an octahedral geometry around Co2+, Ni2+ and Mn2+ complexes, a distorted octahedral geometry around Cu2+ and a tetrahedral geometry around Zn2+ have been proposed. The metal complexes were screened for the antifungal activity.

  1. Spectroscopic, thermal, antimicrobial and molecular modeling studies of mononuclear pentafunctional Schiff base metal chelates derived from 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione

    Science.gov (United States)

    Adly, Omima M. I.; Taha, Ali; Fahmy, Shery A.

    2015-03-01

    A new pentafunctional N3O2 Schiff base, H2L ligand, and its metal chelates with Cu(II), Ni(II), Co(II), VO(IV), Zn(II), Cd(II), Ce(III), Cr(III), Fe(III) and UO2(VI) have been synthesized and characterized by elemental analysis, spectral, molar conductance, magnetic and thermal gravimetric studies. The results showed that the complexes have octahedral geometry except UO2 complex which has pentagonal bipyramidal arrangement. The TGA analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for decomposition steps of metal complexes thermograms have been calculated. Molecular orbital calculations were performed for the ligand and its metal complexes by means of hyperchem 7.52 program on the bases of semiempirical PM3 level and the results were correlated with the experimental data. The antimicrobial activity of the synthesized compounds were tested in vitro against some Gram-positive and Gram-negative bacteria; yeast and fungus strains and the results were discussed in terms of extended Lewis acid-base interactions.

  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. 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.

  4. 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)

  5. Complex forming competition and in-vitro toxicity studies on the applicability of di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT) as a metal chelator.

    Science.gov (United States)

    Gaál, Anikó; Orgován, Gábor; Polgári, Zsófia; Réti, Andrea; Mihucz, Victor G; Bősze, Szilvia; Szoboszlai, Norbert; Streli, Christina

    2014-01-01

    Di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT) is a potential candidate in chelation therapy as an iron chelator. This study showed that a combined treatment with 2μM easily available Fe(II), Cu(II) and Zn(II) each and 5μM Dp44mT on eight different cancer cell lines resulted in a 10-40-fold increase in the intracellular Cu content compared to control samples. The uptake of Cu and Cu-dependent cytotoxicity strictly depend on the Cu concentration of the culture medium. Even as low concentration of Dp44mT as 0.1μM can transport high amounts of copper inside the cells. The Cu accumulation and toxicity through Dp44mT can hardly be influenced by Fe. Copper uptake and toxicity triggered by 2μM extracellular Cu(II) and 5μM Dp44mT could not be influenced by Fe(II) extracellular concentrations even 50-times higher than that of Cu(II). A 50-times higher Co(II) extracellular concentration hindered the Cu(II) uptake almost completely and a 10-times higher Co(II) concentration already decreased the Dp44mT-mediated Cu toxicity. Conditional complex stability constant determinations for Dp44mT with Cu(II), Co(II), Fe(II), Ni(II) and Zn(II) revealed that the metal-to-ligand ratio is 1:1 in [Cu(II)Dp44mT] complex, while for Co(II), Fe(II) and Ni(II) is 1:2. The highest stability constant was obtained for Cu(II) (lg β=7.08±0.05) and Co(II) (lg β2=12.47±0.07). According to our results, Dp44mT in combination with Cu is highly toxic in vitro. Therefore, the use of Dp44mT as an iron chelator is limited if biologically available Cu is also present even at low concentrations. © 2013.

  6. Protective effect of some chelating agents and antioxidants on the ...

    African Journals Online (AJOL)

    Background: Heavy metals that normally cause problems are mercury (HgCl2) and lead acetate (LA). Chelating and inhibitor agents are the target to treat and overcome metal toxicity. The current study has been carried out to evaluate the protective effects of N-acetyl cysteine (NAC) and meso 2,3 dimercaptosuccinic acid ...

  7. Rhodium complexes of a chelating ligand with imidazol-2-ylidene and pyridin-2-ylidene donors: the effect of C-metalation of nicotinamide groups on uptake of hydride ion.

    Science.gov (United States)

    McSkimming, Alex; Ball, Graham E; Bhadbhade, Mohan M; Colbran, Stephen B

    2012-02-20

    Rhodium complexes of the imidazolylidene (C-im) N-heterocyclic carbene (NHC) ligand, C-im-pyH(+), bearing a nicotinamide cation substituent (pyH(+)) have been targeted for ligand-centered uptake and delivery of hydride ion. This work reveals that rhodium(I) complexes such as [Rh(C-im-pyH(+))(COD)X][PF(6)] (1, a: X = Cl, b: X = I) undergo facile C-metalation of the nicotinamide ring to afford rhodium complexes of a novel chelate ligand, C,C'-im-py, with coordinated imidazolylidene (C(im)) and pyridylidene (C(py)) NHC-donors. Seven examples were characterized and include rhodium(III) monomers of the general formula [Rh(C,C'-im-py)L(x)I(2)](z+) (2: z = 1, L = H(2)O or solvent, x = 2; 3, 5, 7: z = 0, L = carboxylate, x = 1) and novel rhodium(II) dimers, the anti/syn-isomers of [Rh(2)(C,C'-im-py)(2)(μOAc)(2)I(2)] (4-anti/syn). The NMR data, backed by DFT calculations, is consistent with attribution of the C,C'-im-py ligand as a bis(carbene) donor. Single crystal X-ray diffraction studies are reported for 2, 3, 4-anti, 4-syn and 7. Consistently, within the each complex, the Rh-C(im) bond length is shorter than the Rh-C(py) bond length, which is the opposite trend to that expected based on simple electronic considerations. It is proposed that intramolecular steric interactions imposed by different rings in the rigid C,C'-im-py chelate ligand dictate the observed Rh-C(NHC) bond lengths. Attempts to add hydride to the C-metalated nicotinamide ring in 3 were unsuccessful. The redox behavior of 3 and 4 and, for comparison, an analogous bis(imidazolylidene)rhodium(III) monomer (8), were characterized by cyclic voltammetry, electron paramagnetic resonance (EPR), and UV-vis spectroelectrochemistry. In 3 and 4, the C-metalated nicotinamide ring is found to exhibit a one-electron reduction process at far lower potential (-2.34 V vs. Fc(+)/Fc in acetonitrile) than the two-electron nicotinamide cation-dihydronicotinamide couple found for the corresponding nonmetalated ring (-1.24 V

  8. Synthesis and characterization of ligational behavior of curcumin drug towards some transition metal ions: Chelation effect on their thermal stability and biological activity

    Science.gov (United States)

    Refat, Moamen S.

    2013-03-01

    Complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with curcumin ligand as antitumor activity were synthesized and characterized by elemental analysis, conductometry, magnetic susceptibility, UV-Vis, IR, Raman, ESR, 1H-NMR spectroscopy, X-ray diffraction analysis of powdered samples and thermal analysis, and screened for antimicrobial activity. The IR spectral data suggested that the ligand behaves as a monobasic bidentate ligand towards the central metal ion with an oxygen's donor atoms sequence of both sbnd OH and Cdbnd O groups under keto-enol structure. From the microanalytical data, the stoichiometry of the complexes 1:2 (metal:ligand) was found. The ligand and their metal complexes were screened for antibacterial activity against Escherichia Coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa and fungicidal activity against Aspergillus flavus and Candida albicans.

  9. Cellulose bearing Schiff base and carboxylic acid chelating groups: a low cost and green adsorbent for heavy metal ion removal from aqueous solution.

    Science.gov (United States)

    Saravanan, R; Ravikumar, L

    2016-10-01

    Chemically modified cellulose bearing metal binding sites like Schiff base and carboxylic acid groups was synthesized and characterized through Fourier transform infrared and solid state 13 C-nuclear magnetic resonance (NMR) analysis. The chemically modified cellulose (Cell-PA) adsorbent was examined for its metal ion uptake ability for Cu(II) and Pb(II) ions from aqueous solution. Kinetic and isotherm studies were carried out under optimum conditions. Pseudo-second-order kinetics and Langmuir isotherm fit well with the experimental data. Thermodynamic studies were also performed along with adsorption regeneration performance studies. The adsorbent (Cell-PA) shows high potential for the removal of Cu(II) and Pb(II) metal ions, and it shows antibacterial activity towards selected microorganisms.

  10. Synthesis Characterization and Antimicrobial Activity of Metal Chelates of 1, 7-Di (2-hydroxyphenyl 1, 7 di (N-methyl aza-1, 3, 5 heptarine-3-ol hydrochloride

    Directory of Open Access Journals (Sweden)

    Nalin P. Patani

    2010-01-01

    Full Text Available The Schiff base complexes derived from 2-furancarboxaldehyde and N-methyl-2-amino phenol have been prepared and characterized using several physical techniques, like elemental analysis, thermogravimetric analysis, magnetic moment measurements, infrared and resonance spectra. N-Methyl-2-amino phenol was condensed stoichiometrically with 2-furancarboxaldehyde in presence of methanol. The resulting 1,7-di(2-hydroxyphenyl 1,7 di(N-methyl aza-1,3,5 heptarine-3-ol hydrochloride was characterized by elemental analysis and spectral studies. The transition metal complexes of Cu2+, Zn2+, Ni2+, Co2+ and Mn2+ of the synthesized complexes were prepared. Metal ligand (M:L ratio, IR, reflectance spectral studies, magnetic properties and antimicrobial activity of the synthesized complexes and its metal complexes were carried out.

  11. 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.

  12. 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.

  13. REGIONAL SIDEROSIS: A NEW CHALLENGE FOR IRON CHELATION THERAPY

    Directory of Open Access Journals (Sweden)

    Zvi Ioav Cabantchik

    2013-12-01

    Full Text Available The traditional role of iron chelation therapy has been to reduce body iron burden via chelation of excess metal from organs and fluids and its excretion via biliary-fecal and/or urinary routes. In their present use for hemosiderosis, chelation regimens might not be suitable for treating disorders of iron maldistribution, as those are characterized by toxic islands of siderosis appearing in a background of normal or subnormal iron levels (e.g. sideroblastic anemias, neuro- and cardio-siderosis in Friedreich ataxia- and neurosiderosis in Parkinson’s disease. We aimed at clearing local siderosis from aberrant labile metal that promotes oxidative damage, without interfering with essential local functions or with hematological iron-associated properties. For this purpose we introduced a conservative mode of iron chelation based on dual activity based on scavenging labile metal but also redeploying it to cell acceptors or to physiological transferrin. The scavenging and redeployment mode of action was designed both for correcting aberrant iron distribution and also for minimizing/preventing systemic loss of chelated metal. We first examine cell models that recapitulate iron maldistribution and associated dysfunctions identified with Friedreich ataxia and Parkinson’s disease and use them to explore the ability of the double-acting agent deferiprone, an orally active chelator, to mediate iron scavenging and redeployment and thereby causing functional improvement. We subsequently evaluate the concept in translational models of disease and finally assess its therapeutic potential in prospective double-blind pilot clinical trials. We claim that any chelator applied to diseases of regional siderosis, cardiac, neuronal or endocrine ought to preserve both systemic and regional iron levels. The proposed deferiprone-based therapy has provided a paradigm for treating regional types of siderosis without affecting hematological parameters and systemic

  14. Regional siderosis: a new challenge for iron chelation therapy.

    Science.gov (United States)

    Cabantchik, Zvi Ioav; Munnich, Arnold; Youdim, Moussa B; Devos, David

    2013-12-31

    The traditional role of iron chelation therapy has been to reduce body iron burden via chelation of excess metal from organs and fluids and its excretion via biliary-fecal and/or urinary routes. In their present use for hemosiderosis, chelation regimens might not be suitable for treating disorders of iron maldistribution, as those are characterized by toxic islands of siderosis appearing in a background of normal or subnormal iron levels (e.g., sideroblastic anemias, neuro- and cardio-siderosis in Friedreich ataxia- and neurosiderosis in Parkinson's disease). We aimed at clearing local siderosis from aberrant labile metal that promotes oxidative damage, without interfering with essential local functions or with hematological iron-associated properties. For this purpose we introduced a conservative mode of iron chelation of dual activity, one based on scavenging labile metal but also redeploying it to cell acceptors or to physiological transferrin. The "scavenging and redeployment" mode of action was designed both for correcting aberrant iron distribution and also for minimizing/preventing systemic loss of chelated metal. We first examine cell models that recapitulate iron maldistribution and associated dysfunctions identified with Friedreich ataxia and Parkinson's disease and use them to explore the ability of the double-acting agent deferiprone, an orally active chelator, to mediate iron scavenging and redeployment and thereby causing functional improvement. We subsequently evaluate the concept in translational models of disease and finally assess its therapeutic potential in prospective double-blind pilot clinical trials. We claim that any chelator applied to diseases of regional siderosis, cardiac, neuronal or endocrine ought to preserve both systemic and regional iron levels. The proposed deferiprone-based therapy has provided a paradigm for treating regional types of siderosis without affecting hematological parameters and systemic functions.

  15. 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.

  16. The use of new modified poly(acrylamide chelating resin with pendent benzothiazole groups containing donor atoms in the removal of heavy metal ions from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Semmedu Selvaraj Kalaivani

    2014-03-01

    Full Text Available The adsorption studies of poly(6-(ethoxybenzothiazole acrylamide (PEBTA, for Cu(II and Zn(II metal ions removal from an aqueous solution have been investigated, as a function of solution pH, adsorbent dose, contact time, initial metal ion concentration and temperature. The chemical and structural characteristics of the adsorbent were determined by the FT-IR, 1H-NMR, TGA, SEM, and EDAX analysis. The maximum adsorption capacities of the adsorbent for Cu(II and Zn(II ions, as calculated from the Langmuir isotherm model, were 273.5 and 216.4 mg/g, respectively. The adsorption kinetic studies show that the adsorption of Cu(II and Zn(II ions onto PEBTA follows the pseudo second order kinetic model. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were also evaluated, and it has been found that the adsorption process is feasible, spontaneous and exothermic in nature. Desorption studies were carried out using 0.3 N HCl, and it revealed that the adsorbed Cu(II and Zn(II ions can be easily removed. The adsorption–desorption process is reversible, and this indicates that PEBTA is an effective adsorbent for the removal of heavy metal ions from an aqueous medium.

  17. Kemampuan Berbagai Putih Telur Unggas Sebagai Kelator dalam Mengatasi Keracunan Logam Berat Timbal (THE ABILITY OF VARIOUS AVIAN EGG ALBUMEN AS A CHELATOR TO OVERCOME LEAD HEAVY METALS TOXICITY

    Directory of Open Access Journals (Sweden)

    Aulia Andi Mustika

    2014-10-01

    Full Text Available Protein in albumen can be chelated and create strong bond with lead. The research was done toevaluate the speed of chelating process by local chicken egg, layers chicken egg, mojokerto duck egg, andpeking duck egg. The experiment was conducted by mixing lead acetat with albumen on 1:1 ratio. White eggconcentrations were divided into 25%, 50%, 75%, and 100%. Control group used 0% of albumen concentration(aquadestilate. Peking duck white egg had the fastest speed of protein chelation. Peking duck albumen by100% concentration had the fastest speed of chelation among the other egg used in experiment (p<0,05. Inconclusion, albumen can be used to overcome lead toxicity, with various speed of chelating process amongalbumen of various alvian.

  18. Grafted-double walled carbon nanotubes as electrochemical platforms for immobilization of antibodies using a metallic-complex chelating polymer: Application to the determination of adiponectin cytokine in serum.

    Science.gov (United States)

    Ojeda, Irene; Barrejón, Myriam; Arellano, Luis M; González-Cortés, Araceli; Yáñez-Sedeño, Paloma; Langa, Fernando; Pingarrón, José M

    2015-12-15

    An electrochemical immunosensor for adiponectin (APN) using screen printed carbon electrodes (SPCEs) modified with functionalized double-walled carbon nanotubes (DWCNTs) as platforms for immobilization of the specific antibodies is reported. DWCNTs were functionalized by treatment with 4-aminobenzoic acid (HOOC-Phe) in the presence of isoamylnitrite resulting in the formation of 4-carboxyphenyl-DWCNTs. The oriented binding of specific antibodies toward adiponectin was accomplished by using the metallic-complex chelating polymer Mix&Go™. The HOOC-Phe-DWCNTs-modified SPCEs were characterized by cyclic voltammetry and compared with HOOC-Phe-SWCNTs/SPCE. The different variables affecting the performance of the developed immunosensor were optimized. Under the selected conditions, a calibration plot for APN was constructed showing a range of linearity extending between 0.05 and 10.0 μg/mL which is adequate for the determination of the cytokine in real samples. A detection limit of 14.5 ng/mL was achieved. The so prepared immunosensor exhibited a good reproducibility for the APN measurements, excellent storage stability and selectivity, and a much shorter assay time than the available ELISA kits. The usefulness of the immunosensor for the analysis of real samples was demonstrated by analyzing human serum from female or male healthy patients. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Structure of the first representative of Pfam family PF04016 (DUF364) reveals enolase and Rossmann-like folds that combine to form a unique active site with a possible role in heavy-metal chelation

    International Nuclear Information System (INIS)

    Miller, Mitchell D.; Aravind, L.; Bakolitsa, Constantina; Rife, Christopher L.; Carlton, Dennis; Abdubek, Polat; Astakhova, Tamara; Axelrod, Herbert L.; Chiu, Hsiu-Ju; Clayton, Thomas; Deller, Marc C.; Duan, Lian; Feuerhelm, Julie; Grant, Joanna C.; Han, Gye Won; Jaroszewski, Lukasz; Jin, Kevin K.; Klock, Heath E.; Knuth, Mark W.; Kozbial, Piotr; Krishna, S. Sri; Kumar, Abhinav; Marciano, David; McMullan, Daniel; Morse, Andrew T.; Nigoghossian, Edward; Okach, Linda; Reyes, Ron; Bedem, Henry van den; Weekes, Dana; Xu, Qingping; Hodgson, Keith O.; Wooley, John; Elsliger, Marc-André; Deacon, Ashley M.; Godzik, Adam; Lesley, Scott A.; Wilson, Ian A.

    2010-01-01

    The crystal structure of the first representative of DUF364 family reveals a combination of enolase N-terminal-like and C-terminal Rossmann-like folds. Analysis of the interdomain cleft combined with sequence and genome context conservation among homologs, suggests a unique catalytic site likely involved in the synthesis of a flavin or pterin derivative. The crystal structure of Dhaf4260 from Desulfitobacterium hafniense DCB-2 was determined by single-wavelength anomalous diffraction (SAD) to a resolution of 2.01 Å using the semi-automated high-throughput pipeline of the Joint Center for Structural Genomics (JCSG) as part of the NIGMS Protein Structure Initiative (PSI). This protein structure is the first representative of the PF04016 (DUF364) Pfam family and reveals a novel combination of two well known domains (an enolase N-terminal-like fold followed by a Rossmann-like domain). Structural and bioinformatic analyses reveal partial similarities to Rossmann-like methyltransferases, with residues from the enolase-like fold combining to form a unique active site that is likely to be involved in the condensation or hydrolysis of molecules implicated in the synthesis of flavins, pterins or other siderophores. The genome context of Dhaf4260 and homologs additionally supports a role in heavy-metal chelation

  20. Novel polycatecholamide chelating agents

    Science.gov (United States)

    Weitl, F.L.; Raymond, K.N.

    1981-08-24

    Novel polybenzamide compounds useful for in vitro or in vivo chelation are described. Formulas of the compounds are given. To prepare them polyamines are reacted with 2,3-dimethoxy benzoyl chloride unsubstituted or substituted with SO/sub 3/H, SO/sub 3/M, NO/sub 2/, CO/sub 2/H or CO/sub 2/M as desired is reacted with a polyamine in an inert solvent then demethylated with BBr/sub 3/ or BCl/sub 3/ in an inert solvent. Where compounds symmetrically substituted on the terminal N's are desired, the polyamine is first reductively alkylated by reaction with an aldehyde or ketone and the resulting Schiff base is hydrogenated.

  1. EDTA: the chelating agent under environmental scrutiny

    Directory of Open Access Journals (Sweden)

    Claudia Oviedo

    2003-12-01

    Full Text Available The chelating agent EDTA (ethylenediaminetetraacetic acid is a compound of massive use world wide with household and industrial applications, being one of the anthropogenic compounds with highest concentrations in inland European waters. In this review, the applications of EDTA and its behavior once it has been released into the environment are described. At a laboratory scale, degradation of EDTA has been achieved; however, in natural environments studies detect poor biodegradability. It is concluded that EDTA behaves as a persistent substance in the environment and that its contribution to heavy metals bioavailability and remobilization processes in the environment is a major concern.

  2. Synthesis, structural characterization, electrochemical and biological studies on divalent metal chelates of a new ligand derived from pharmaceutical preservative, dehydroacetic acid, with 1,4-diaminobenzene

    Directory of Open Access Journals (Sweden)

    Sanaa M. Emam

    2017-05-01

    Full Text Available Cobalt(II, nickel(II, copper(II, zinc(II and cadmium(II complexes of new 3-acetyl-4-[(4-aminophenylamino]-6-methyl-2H-pyran-2-one (HL1 derived from dehydroacetic acid and 1,4-diaminobenzene were prepared and characterized. The structural features were determined from their elemental analyses, 1H, and 13C-NMR spectra, molar conductivities, magnetic moments, IR, UVvis. spectra, thermal analyses (D.T.A. and T.G.A. and E.S.R. measurements. Their magnetic susceptibility measurements and low conductance data provide evidence for the mono- or dimeric and non-electrolytic nature of the solid complexes. The E.S.R. spectra of copper(II complexes show axial type symmetry with covalent or ionic bond character. The electrochemical behavior of the complexes in DMF (dimethylformamide solvent at 298 K was studied. The biological activity of the ligand and its metal(II complexes was also studied. The obtained complexes showed higher activities than the free ligand in protecting the Egyptian cotton fields from Spodoptera littoralis larvae.

  3. 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.)

  4. Study of the chemical chelates and anti-microbial effect of some metal ions in nanostructural form on the efficiency of antibiotic therapy "norfloxacin drug"

    Science.gov (United States)

    Refat, Moamen S.; El-Hawary, W. F.; Mohamed, Mahmoud A.

    2012-04-01

    This paper has reviewed the chemical and biological impact resulting from the interaction between norfloxacin (norH) antibiotic drug and two lanthanide (lanthanum(III) and cerium(III)) metal ions, which prepared in normal and nano-features. La(III) and Ce(III) complexes were synthesized with chemical formulas [La(nor)3]·3H2O and [Ce(nor)3]·2H2O. Lanthanum and cerium(III) ions coordinated toward norH with a hexadentate geometry. The norH acts as deprotonated bidentate ligand through the oxygen atom of carbonyl group and the oxygen atom of carboxylic group. Elemental analysis, FT-IR spectral, electrical conductivity, thermal analysis (TG/DTA), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) measurements have been used to characterize the mentioned isolated complexes. The Coats-Redfern and Horowitz-Metzger integral methods are used to estimate the kinetic parameters for the major successive steps detectable in the TG curve. The brightness side in this study is to take advantage for the preparation and characterization of single phases of La2O3 and CeO2 nanoparticles using urea as precursors via a solid-state decomposition procedure. The norH ligand in comparison with both cases (normal and nano-particles) of lanthanide complexes were screened against for antibacterial (Escherichia Coli, Staphylococcus Aureus, Bacillus subtilis and Pseudomonas aeruginosa) and antifungal (Aspergillus Flavus and Candida Albicans) activities. The highest antibacterial and antifungal activities data of the nano-particles complexes were observed with more potent than the free norH and normal lanthanide complexes.

  5. Cyclohexylamine as extraction solvent and chelating agent in extraction and preconcentration of some heavy metals in aqueous samples based on heat-induced homogeneous liquid-liquid extraction.

    Science.gov (United States)

    Sorouraddin, Saeed Mohammad; Farajzadeh, Mir Ali; Okhravi, Tohid

    2017-12-01

    A new sample preparation method has been developed for extraction and preconcentration of some heavy metal cations in aqueous samples using cyclohexylamine-based homogeneous liquid-liquid microextraction. In the proposed method, cyclohexylamine was used as both the complexing agent and the extraction solvent. For this purpose, cyclohexylamine at µL level was initially added into an aqueous solution containing Co(II), Ni(II), and Cu(II) ions which was placed in a glass test tube. The mixture was shaken for forming a homogeneous solution. Then sodium chloride was added to the solution. After shaking manually again, the test tube was placed in a water bath thermostated at 70°C. Due to lower solubility of cyclohexylamine at the elevated temperature, a cloudy solution was formed. The fine droplets of cyclohexylamine containing cation-cyclohexylamine complexes were collected on the top of the aqueous phase by centrifuging. The enriched analytes in the upper phase were determined by graphite furnace atomic absorption spectrometry. Several variables possibly affecting the extraction efficiency were investigated and optimized. Under the optimum conditions the calibration curves were linear in the ranges of 80-1000, 40-700, and 80-800ngL -1 for Co 2+ , Ni 2+ , and Cu 2+ , respectively. Repeatability of the proposed method, expressed as relative standard deviation, ranged from 3.3% to 5.2% (n = 6, C = 200ngL -1 ). Moreover, the obtained detection limits of the selected analytes were in the range of 15.3-37.7ngL -1 . The accuracy of the developed procedure was verified by analyzing a certified reference material, namely NRCC-SLRS4 Riverine water. Finally, the proposed method was successfully applied for the simultaneous analysis of the selected analytes in environmental water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Gadolinium Retention, Brain T1 Hyperintensity, and Endogenous Metals: A Comparative Study of Macrocyclic Versus Linear Gadolinium Chelates in Renally Sensitized Rats.

    Science.gov (United States)

    Rasschaert, Marlène; Emerit, Andréa; Fretellier, Nathalie; Factor, Cécile; Robert, Philippe; Idée, Jean-Marc; Corot, Claire

    2018-01-12

    This preclinical study was designed to compare gadolinium (Gd) brain uptake after repeated injections of a macrocyclic Gd-based contrast agent (GBCA) (gadoterate meglumine) or 2 linear GBCAs (L-GBCAs) (gadobenate dimeglumine or gadodiamide) on a translational model of moderate renal impairment in rats. The study was carried out in subtotally nephrectomized rats. Animals received 4 intravenous injections per week of GBCA (gadoterate meglumine, gadobenate dimeglumine, or gadodiamide) for 5 weeks, resulting in a cumulative dose of 12 mmol/kg, followed by a 1-month injection-free period. T1 hyperintensity in the deep cerebellar nuclei (DCNs) was investigated, and brain structures were carefully dissected to determine elemental Gd, iron (Fe), copper (Cu), and zinc (Zn) distribution by mass spectrometry. Urinary excretion of endogenous metals was also investigated soon after GBCA administration and several days later in order to assess a potential transmetalation phenomenon. Unlike gadoterate, repeated injections of L-GBCAs gadobenate and gadodiamide both induced T1 hyperintensity in the DCNs. Fine dissection of cerebral and cerebellar structures demonstrated very low levels or absence of Gd after repeated injections of gadoterate, in contrast to the two L-GBCAs, for which the highest total Gd concentration was demonstrated in the DCNs (Gd concentration in DCNs after 4.5 weeks of injection-free period: 27.1 ± 6.5 nmol/g for gadodiamide [P download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

  7. Microwave Irradiation-Assisted Synthesis of a Novel Crown Ether Crosslinked Chitosan as a Chelating Agent for Heavy Metal Ions (M+n

    Directory of Open Access Journals (Sweden)

    Ibrahim A. Alsarra

    2010-09-01

    Full Text Available Microwave irradiation was used to obtain a di-Schiff base type crosslinked chitosan dibenzocrown ether (CCdBE via the reaction between the –NH2 and –CHO groups in chitosan and 4,4′-diformyldibenzo-18-c-6, respectively. The structure of the synthesized compound was characterized by elemental analysis, solid state 13C-NMR and FT-IR spectra analysis. The results showed that the mass fraction of nitrogen in the CCdBE derivative was much lower than those of chitosan. The FT-IR spectra of CCdBE revealed the expected chitosan-crown ether structure, as evidenced by the presence of the characteristic C=N and Ar peaks. The adsorption properties of CCdBE for Pd2+ and Hg2+ were investigated and the results demonstrated that the adsorbent has both desirable adsorption properties with a high particular adsorption selectivity for Hg2+ when in the presence of Pb2+ as well as selectivity coefficients for metal ions of KHg2+ /Pb2+ = 8.00 and KHg 2+/Pb2+ = 10.62 at pH values of 4 and 6, respectively. The reusability tests for CCdBE for Pb2+ adsorption showed that complete recovery of the ion was possible with CCdBE after 10-multiple reuses while CTS had no reusability at acidic solution because of its higher dissolution. The studied features of CCdBE suggested that the material could be considered as a new adsorbent. It is envisaged that the crosslinking of CTS into CCdBE would enhance practicality and effectiveness of adsorption in ion separation and removal procedures.

  8. Ab initio coordination chemistry for nickel chelation motifs.

    Science.gov (United States)

    Sudan, R Jesu Jaya; Kumari, J Lesitha Jeeva; Sudandiradoss, C

    2015-01-01

    Chelation therapy is one of the most appreciated methods in the treatment of metal induced disease predisposition. Coordination chemistry provides a way to understand metal association in biological structures. In this work we have implemented coordination chemistry to study nickel coordination due to its high impact in industrial usage and thereby health consequences. This paper reports the analysis of nickel coordination from a large dataset of nickel bound structures and sequences. Coordination patterns predicted from the structures are reported in terms of donors, chelate length, coordination number, chelate geometry, structural fold and architecture. The analysis revealed histidine as the most favored residue in nickel coordination. The most common chelates identified were histidine based namely HHH, HDH, HEH and HH spaced at specific intervals. Though a maximum coordination number of 8 was observed, the presence of a single protein donor was noted to be mandatory in nickel coordination. The coordination pattern did not reveal any specific fold, nevertheless we report preferable residue spacing for specific structural architecture. In contrast, the analysis of nickel binding proteins from bacterial and archeal species revealed no common coordination patterns. Nickel binding sequence motifs were noted to be organism specific and protein class specific. As a result we identified about 13 signatures derived from 13 classes of nickel binding proteins. The specifications on nickel coordination presented in this paper will prove beneficial for developing better chelation strategies.

  9. Sequestration of zinc oxide by fimbrial designer chelators

    DEFF Research Database (Denmark)

    Kjærgaard, Kristian; Sørensen, Jack K; Schembri, Mark

    2000-01-01

    Type 1 fimbriae are surface organelles of Escherichia coli. By engineering a structural component of the fimbriae, FimH, to display a random peptide library, we were able to isolate metal-chelating bacteria. A library consisting of 4 x 10(7) independent clones was screened for binding to Zn...

  10. Metal based pharmacologically active agents: Synthesis, structural characterization, molecular modeling, CT-DNA binding studies and in vitro antimicrobial screening of iron(II) bromosalicylidene amino acid chelates

    Science.gov (United States)

    Abdel-Rahman, Laila H.; El-Khatib, Rafat M.; Nassr, Lobna A. E.; Abu-Dief, Ahmed M.; Ismael, Mohamed; Seleem, Amin Abdou

    2014-01-01

    flavus and Trichotheium rosium. The results of these studies indicated that the metal complexes exhibit a stronger antibacterial and antifungal efficiency than their corresponding Schiff base amino acid ligands.

  11. 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

  12. 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.

  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. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Gopalan, A.; Jacobs, H.; Koshti, N.; Stark, P.; Huber, V.; Dasaradhi, L.; Caswell, W. [New Mexico State Univ., Las Cruces, NM (United States); Smith, P.; Jarvinen, G. [Los Alamos National Lab., NM (United States)

    1995-08-01

    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.

  17. METAL CHELATING AGENTS IV: ELECTRON IONIZATION AND ...

    African Journals Online (AJOL)

    The electron ionization (EI) and ammonia chemical ionization [CI (NH3)] mass spectral studies on 2-phenyl acetophenone semicarbazone are reported. The El spectrum shows a clearly identifiable molecular ion peak of weak intensity at m/z 253 and the base peak is observed at m/z 77. The CI (NH3) spectrum is ...

  18. Oxidation-Induced Degradable Nanogels for Iron Chelation

    Science.gov (United States)

    Liu, Zhi; Wang, Yan; Purro, Max; Xiong, May P.

    2016-02-01

    Iron overload can increase cellular oxidative stress levels due to formation of reactive oxygen species (ROS); untreated, it can be extremely destructive to organs and fatal to patients. Since elevated oxidative stress levels are inherent to the condition in such patients, oxidation-induced degradable nanogels for iron chelation were rationally designed by simultaneously polymerizing oxidation-sensitive host-guest crosslinkers between β-cyclodextrin (β-CD) and ferrocene (Fc) and iron chelating moieties composed of deferoxamine (DFO) into the final gel scaffold in reverse emulsion reaction chambers. UV-Vis absorption and atomic absorption spectroscopy (AAS) was used to verify iron chelating capability of nanogels. These materials can degrade into smaller chelating fragments at rates proportional to the level of oxidative stress present. Conjugating DFO reduces the cytotoxicity of the chelator in the macrophage cells. Importantly, the nanogel can effectively reduce cellular ferritin expression in iron overloaded cells and regulate intracellular iron levels at the same time, which is important for maintaining a homeostatic level of this critical metal in cells.

  19. 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

  20. Determination of trace metal ions via on-line separation and preconcentration by means of chelating Sepharose beads in a sequential injection lab-on-valve (SI-LOV) system coupled to electrothermal atomic absorption spectrometric detection

    DEFF Research Database (Denmark)

    Long, Xiangbao; Hansen, Elo Harald; Miró, Manuel

    2005-01-01

    The analytical performance of an on-line sequential injection lab-on-valve (SI-LOV) system using chelating Sepharose beads as sorbent material for the determination of ultra trace levels of Cd(II), Pb(II) and Ni(II) by electrothermal atomic absorption spectrometry (ETAAS) is described and discussed...

  1. 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)

  2. Iron Chelation and Multiple Sclerosis

    Directory of Open Access Journals (Sweden)

    Kelsey J. Weigel

    2014-01-01

    Full Text Available Histochemical and MRI studies have demonstrated that MS (multiple sclerosis patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6–8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood–brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.

  3. 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.

  4. 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.

  5. 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.

  6. 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...

  7. Combination therapies in iron chelation

    Directory of Open Access Journals (Sweden)

    Raffaella Origa

    2014-12-01

    Full Text Available The availability of oral iron chelators and new non-invasive methods for early detection and treatment of iron overload, have significantly improved the life expectancy and quality of life of patients with b thalassemia major. However, monotherapy is not effective in all patients for a variety of reasons. We analyzed the most relevant reports recently published on alternating or combined chelation therapies in thalassemia major with special attention to safety aspects and to their effects in terms of reduction of iron overload in different organs, improvement of complications, and survival. When adverse effects, such as gastrointestinal upset with deferasirox or infusional site reactions with deferoxamine are not tolerable and organ iron is in an acceptable range, alternating use of two chelators (drugs taken sequentially on different days, but not taken on the same day together may be a winning choice. The association deferiprone and deferoxamine should be the first choice in case of heart failure and when dangerously high levels of cardiac iron exist. Further research regarding the safety and efficacy of the most appealing combination treatment, deferiprone and deferasirox, is needed before recommendations for routine clinical practice can be made.

  8. Effects of chelators on mercury, iron, and lead neurotoxicity in cortical culture.

    Science.gov (United States)

    Rush, Travis; Hjelmhaug, Julie; Lobner, Doug

    2009-01-01

    Chelation therapy for the treatment of acute, high dose exposure to heavy metals is accepted medical practice. However, a much wider use of metal chelators is by alternative health practitioners for so called "chelation therapy". Given this widespread and largely unregulated use of metal chelators it is important to understand the actions of these compounds. We tested the effects of four commonly used metal chelators, calcium disodium ethylenediaminetetraacetate (CaNa2EDTA), D-penicillamine (DPA), 2,3 dimercaptopropane-1-sulfonate (DMPS), and dimercaptosuccinic acid (DMSA) for their effects on heavy metal neurotoxicity in primary cortical cultures. We studied the toxicity of three forms of mercury, inorganic mercury (HgCl2), methyl mercury (MeHg), and ethyl mercury (thimerosal), as well as lead (PbCl2) and iron (Fe-citrate). DPA had the worst profile of effects, providing no protection while potentiating HgCl2, thimerosal, and Fe-citrate toxicity. DMPS and DMSA both attenuated HgCl2 toxicity and potentiated thimerosal and Fe toxicity, while DMPS also potentiated PbCl2 toxicity. CaNa2EDTA attenuated HgCl2 toxicity, but caused a severe potentiation of Fe-citrate toxicity. The ability of these chelators to attenuate the toxicity of various metals is quite restricted, and potentiation of toxicity is a serious concern. Specifically, protection is provided only against inorganic mercury, while it is lacking against the common form of mercury found in food, MeHg, and the form found in vaccines, thimerosal. The potentiation of Fe-citrate toxicity is of concern because of iron's role in oxidative stress in the body. Potentiation of iron toxicity could have serious health consequences when using chelation therapy.

  9. Hydroxypyri(mi)dine-based chelators as antidotes of toxicity due to aluminum and actinides.

    Science.gov (United States)

    Santos, M A; Esteves, M A; Chaves, S

    2012-01-01

    This review is focused on recent developments on hydroxypyri(mi)dines, as aluminum and actinide chelating agents to combat the toxicity due to accumulations of these metal ions in human body resulting from excessive metal exposure. After a brief update revision of the most common processes of aluminum (Al) exposure, as well as the associated toxicities and pathologies, we will focus on the current available Al chelators and future perspective as potential antidotes of Al toxicity. Due to the similarity between Al and Fe, a major emphasis is given to the hydroxypyridinone and hydroxypyrimidinone chelators, since they are analogues of the current iron chelators in clinical use (DFP and DFO). This review includes issues such as molecular design strategies and corresponding effects on the associated physico-chemical properties, lipo-hydrophilic balance, toxicity, in vivo bioassays and current clinical applications. The hydroxypyri(mi)dine chelators are also suitable for other hard metal ions, such as the radiotoxic actinides, and so a brief review is included on the applications of these chelators in actinides scavenging.

  10. Chelating ionic liquids for reversible zinc electrochemistry.

    Science.gov (United States)

    Kar, Mega; Winther-Jensen, Bjorn; Forsyth, Maria; MacFarlane, Douglas R

    2013-05-21

    Advanced, high energy-density, metal-air rechargeable batteries, such as zinc-air, are of intense international interest due to their important role in energy storage applications such as electric and hybrid vehicles, and to their ability to deal with the intermittency of renewable energy sources such as solar and wind. Ionic liquids offer a number of ideal thermal and physical properties as potential electrolytes in such large-scale energy storage applications. We describe here the synthesis and characterisation of a family of novel "chelating" ILs designed to chelate and solubilize the zinc ions to create electrolytes for this type of battery. These are based on quaternary alkoxy alkyl ammonium cations of varying oligo-ether side chains and anions such as p-toluene sulfonate, bis(trifluoromethylsulfonyl)amide and dicyanoamides. This work shows that increasing the ether chain length in the cation from two to four oxygens can increase the ionic conductivity and reduce the melting point from 67 °C to 15 °C for the tosylate system. Changing the anion also plays a significant role in the nature of the zinc deposition electrochemistry. We show that zinc can be reversibly deposited from [N(222(20201))][NTf2] and [N(222(202020201))][NTf2] beginning at -1.4 V and -1.7 V vs. SHE, respectively, but not in the case of tosylate based ILs. This indicates that the [NTf2] is a weaker coordinating anion with the zinc cation, compared to the tosylate anion, allowing the coordination of the ether chain to dominate the behavior of the deposition and stripping of zinc ions.

  11. 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.

  12. 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

  13. Thiosemicarbazone complexes of the platinum metals. A story of ...

    Indian Academy of Sciences (India)

    Unknown

    membered chelate rings; molecular modelling; five-membered chelate ring. 1. Introduction. The chemistry of transition metal complexes of thiosemicarbazones has been receiving considerable attention largely because of their pharmacological ...

  14. 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

  15. 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.

  16. 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

  17. Iron mobilization using chelation and phlebotomy

    DEFF Research Database (Denmark)

    Flaten, T. P.; Aaseth, J.; Andersen, Ole

    2012-01-01

    or subcutaneously, mostly on a daily basis. Thus, there is an obvious need to find and develop new effective iron chelators for oral use. In later years, particularly two such oral iron chelators have shown promise and have been approved for clinical use, namely deferiprone (Ferriprox) and deferasirox (Exjade...

  18. 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...

  19. Importance of iron chelation therapy

    Directory of Open Access Journals (Sweden)

    A. Varoğlu

    2011-12-01

    Full Text Available It is necessary to remember that today patients have different options of chelation treatment, as desferrioxamine, deferiprone and deferasirox are available. However, a patient has to be compliant with treatments. They have always to remember that too much iron causes different complications and could be a barrier for a definitive cure from thalassemia. 由于出现了去铁胺、去铁酮和去铁斯若等药物,病人现在可以选择不同的螯合治疗方式。 然而,病人必须适应这几种治疗方式。 他们必须时刻记住太多的铁元素会引发多种并发症,并对地中海贫血的彻底治疗造成阻碍。

  20. Chelating ligands for nanocrystals' surface functionalization.

    Science.gov (United States)

    Querner, Claudia; Reiss, Peter; Bleuse, Joël; Pron, Adam

    2004-09-22

    A new family of ligands for the surface functionalization of CdSe nanocrystals is proposed, namely alkyl or aryl derivatives of carbodithioic acids (R-C(S)SH). The main advantages of these new ligands are as follows: they nearly quantitatively exchange the initial surface ligands (TOPO) in very mild conditions; they significantly improve the resistance of nanocrystals against photooxidation because of their ability of strong chelate-type binding to metal atoms; their relatively simple preparation via Grignard intermediates facilitates the development of new bifunctional ligands containing, in addition to the anchoring carbodithioate group, a second function, which enables the grafting of molecules or macromolecules of interest on the nanocrystal surface. To give an example of this approach, we report, for the first time, the grafting of an electroactive oligomer from the polyaniline family-aniline tetramer-on CdSe nanocrystals after their functionalization with 4-formyldithiobenzoic acid. The grafting proceeds via a condensation reaction between the aldehyde group of the ligand and the terminal primary amine group of the tetramer. The resulting organic/inorganic hybrid exhibits complete extinction of the fluorescence of its constituents, indicating efficient charge or energy transfer between the organic and the inorganic semiconductors.

  1. 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.

  2. 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

  3. Theoretical study, and infrared and Raman spectra of copper(II) chelated complex with dibenzoylmethane

    DEFF Research Database (Denmark)

    Nekoei, A.-R.; Vakili, M.; Hakimi-Tabar, M.

    2014-01-01

    There are some discrepancies in both the vibrational assignments and in the metal-ligand (M-L) bond strengths predicted in the previous studies on the copper (II) chelated complex of dibenzoylmethane, Cu(dbm)2. Also, there is a lack of theoretical structure, Raman spectrum and full vibrational as...

  4. Leachability of chelated ion-exchange resins solidified in cement or cement and fly ash

    International Nuclear Information System (INIS)

    McIsaac, C.V.

    1993-01-01

    Leach tests were conducted at the Idaho National Engineering Laboratory on six small-scale specimens of cement-solidified ion-exchange resin wastes. The ion-exchange resins had been used to process reagent solutions following chemical decontaminations of primary coolant systems at five commercial light water reactors. The decontaminations were performed using the AP/Citrox, Can-Decon, Dow NS-1, and Low Oxidation-State Transition-Metal ION (LOMI) processes. The ion-exchange resin wastes were loaded with radionuclides, transition metals, and organic chelating agents, and were solidified in either unmodified Portland Type 1 cement or in a mixture of Portland Type 1 cement and fly ash. Waste-form specimens were leach-tested in deionized water at 23C using the American National Standards Institute/American Nuclear Society (ANSI/ANS) Standard 16.1 procedure. Release rates, effective diffusivities, and leachability indexes of radionuclides, chelating agents, and stable metals were determined using ANS-16.1 diffusion release models. Releases of radionuclides, chelating agents, and metals from waste forms that degraded during leaching were similar to releases from waste forms that maintained their physical integrity during leaching. The presence of chelating agents in the waste forms did not adversely affect the leachability of the waste forms

  5. The magnesium chelation step in chlorophyll biosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, J.

    1990-11-01

    In photosynthetic organisms, the biogenesis of energy transducing membranes requires the coordinate synthesis of prosthetic groups, proteins, and various lipids. Two of the major prosthetic groups, chlorophyll and heme, share a common biosynthetic pathway that diverges at the point of metal insertion into protoporphyrin IX (Proto). Insertion of iron leads to the formation of hemes, while insertion of magnesium is the first step unique to chlorophyll formation. This project is directed toward identifying the enzyme(s) responsible for magnesium chelation and elucidating the mechanism which regulates the flux of precursors through the branch point enzymes in isolated chloroplasts. Using intact chloroplasts from greening cucumber cotyledons, we have confirmed the ATP requirement for Mg-Proto formation. Use of non-hydrolyzable ATP analogs, uncouplers and ionophores has led to the conclusions that ATP hydrolysis is necessary, but that this hydrolysis is not linked to the requirement for membrane intactness by transmembrane ion gradients or electrical potentials. The enzyme(s) are flexible with respect to the porphyrin substrate specificity, accepting porphyrins with -vinyl, -ethyl, or -H substituents at the 2 and 4 positions. The activity increases approximately four-fold during greening. Possible physiological feedback inhibitors such as heme, protochlorophyllide, and chlorophyllide had no specific effect on the activity. The activity has now been assayed in barely, corn and peas, with the system from peas almost ten-fold more active than the cucumber system. Work is continuing in pea chloroplasts with the development of a continuous assay and investigation of the feasibility of characterizing an active, organelle-free preparation. 6 figs.

  6. Selective separation of indium by iminodiacetic acid chelating resin

    Energy Technology Data Exchange (ETDEWEB)

    Fortes, M.C.B.; Benedetto, J.S. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Martins, A.H. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Metalurgica e de Materiais]. E-mail: ahmartin@demet.ufmg.br

    2007-04-15

    - 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{sup 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{sup 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{sup 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{sup R} IRC748. (author)

  7. 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

  8. 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.

  9. 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

  10. Immobilized triazacyclononane derivatives as selective oxidation catalysts. Final technical report of DOE Award No. DE-FG02-99ER14968 with the University of Munich [Encapsulation of metal chelate and oxocatalysts in nanoporous hosts

    Energy Technology Data Exchange (ETDEWEB)

    Bein, Thomas

    2002-10-28

    This project deals with the covalent anchoring of various derivatives of triazacyclononane (TACN)ligands in the channels of period mesoporous materials and the catalytic activity of the corresponding metal complexes. Catalyst preparation, ligand immobilization, catalyst characterization, and catalyst performance in selective oxidation are discussed. A wide range of pendant variations on the TACN ligand can be synthesized, and ligands can be covalently bound to high surface area, pseudo-crystalline, silicate solids, before or after pendant addition.

  11. Effects of chelating agents on oral uptake and renal deposition and excretion of cadmium

    International Nuclear Information System (INIS)

    Engstroem, B.

    1984-01-01

    The gastrointestinal absorption, transport, tissue deposition and excretion of cadmium was studied in adult male mice given a single oral LD 50 dose of 109 Cd-labeled CdCl 2 alone or in combination with nitrilotriacetic acid (NTA), sodium tripolyphosphate (STPP) or ethylenediaminetetraacetic acid (EDTA). Blood, intestinal mucosa, liver and kidneys were analyzed for 109 Cd at different times after exposure and the influence of the chelating agents on Cd binding to metallothionein and other tissue ligands was also studied. The effect of different chelating agents on acute cadmium toxicity and metabolism seemed to be due to changes in the stability of the administered chelate complexes, due to variation in pH and to the availability of metal binding ligands such as metallothionein in vivo. NTA, STPP and EDTA had no effect on the metabolism or toxicity of cadmium after long-term low dose oral exposure. 43 references, 4 tables, 9 figures

  12. Stimulus-Responsive Prochelators for Manipulating Cellular Metals

    OpenAIRE

    WANG, QIN; FRANZ, KATHERINE J.

    2016-01-01

    Metal ions are essential for a wide range of physiological processes, but they can also be toxic if not appropriately regulated by a complex network of metal trafficking proteins. Intervention in cellular metal distribution with small molecule or peptide chelating agents has promising therapeutic potential to harness metals to fight disease. Molecular outcomes associated with forming metal-chelate interactions in situ include altering concentration and subcellular metal distribution, inhibiti...

  13. Iron Chelation Inhibits Osteoclastic Differentiation In Vitro and in Tg2576 Mouse Model of Alzheimer's Disease.

    Directory of Open Access Journals (Sweden)

    Jun-Peng Guo

    Full Text Available Patients of Alzheimer's disease (AD frequently have lower bone mineral density and higher rate of hip fracture. Tg2576, a well characterized AD animal model that ubiquitously express Swedish mutant amyloid precursor protein (APPswe, displays not only AD-relevant neuropathology, but also age-dependent bone deficits. However, the underlying mechanisms remain poorly understood. As APP is implicated as a regulator of iron export, and the metal chelation is considered as a potential therapeutic strategy for AD, we examined iron chelation's effect on the osteoporotic deficit in Tg2576 mice. Remarkably, in vivo treatment with iron chelator, clinoquinol (CQ, increased both trabecular and cortical bone-mass, selectively in Tg2576, but not wild type (WT mice. Further in vitro studies showed that low concentrations of CQ as well as deferoxamine (DFO, another iron chelator, selectively inhibited osteoclast (OC differentiation, without an obvious effect on osteoblast (OB differentiation. Intriguingly, both CQ and DFO's inhibitory effect on OC was more potent in bone marrow macrophages (BMMs from Tg2576 mice than that of wild type controls. The reduction of intracellular iron levels in BMMs by CQ was also more dramatic in APPswe-expressing BMMs. Taken together, these results demonstrate a potent inhibition on OC formation and activation in APPswe-expressing BMMs by iron chelation, and reveal a potential therapeutic value of CQ in treating AD-associated osteoporotic deficits.

  14. 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.

  15. 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 life . Strategies to balance medical needs with family, work, and personal life may assist in adherence.

  16. 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

  17. Determining lead, cadmium and mercury in cosmetics using sweeping via dynamic chelation by capillary electrophoresis.

    Science.gov (United States)

    Chen, Kuan-Ling; Jiang, Shiuh-Jen; Chen, Yen-Ling

    2017-03-01

    International limits have been established for metal impurities in cosmetics to prevent overexposure to heavy metal ions. Sweeping via dynamic chelation was developed using capillary electrophoresis to analyze lead (Pb), cadmium (Cd) and mercury (Hg) impurities in cosmetics. The sweeping via dynamic chelation mechanism involves a large volume of metal ions being swept by a small quantity of chelating agents that were electrokinetically injected into the capillary to chelate metal ions and increase the detection sensitivity. The optimized conditions were as follows: Firstly, the capillary was rinsed by a 0.6 mM TTAB solution to reverse the EOF. The sample solution, which was diluted using 25 mM ammonium acetate (pH 6.0), was injected into the capillary using a pressure of 3.5 psi for 99.9 s. Then, EDTA was injected at -25 kV for 1 min from the EDTA buffer (25 mM ammonium acetate containing 0.6 mM TTAB and 5 mM EDTA), and the metal ions were swept and stacked simultaneously. Finally, the separation was performed at -20 kV using a separation buffer (100 mM ammonium acetate (pH 6.0)). A small quantity of chelating agents introduced into the capillary could yield 33-, 50- and 100-fold detection improvements for Pb, Cd and Hg, respectively, more sensitive than conventional capillary zone electrophoresis. Correlation coefficients greater than 0.998 indicated that this method exhibited good linearity. The relative standard deviation and relative error were less than 8.7%, indicating high precision and accuracy. The recovery value of the homemade lotion, which was employed to simulate the real sample matrix, was 93-104%, which indicated that the sample matrix does not affect the quantitative results. Finally, commercial cosmetics were employed to demonstrate the feasibility of the method to determine Pb, Cd and Hg without complicated sample pretreatment. Graphical Abstract The procedure of analyzing metal ions in cosmetics by sweeping via dynamic chelation.

  18. 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

  19. Recent developments centered on orally active iron chelators

    Directory of Open Access Journals (Sweden)

    Robert Hider

    2014-09-01

    Full Text Available Over the past twenty years there has been a growing interest in the orally active iron chelators, deferiprone and deferasirox, both have been extensively studied. The ability of these compounds to mobilize iron from the heart and endocrine tissue has presented the clinician with some advantages over desferrioxamine, the first therapeutic iron chelator. Other orally active iron chelators are currently under development. The critical features necessary for the design of therapeutically useful orally active iron chelators are presented in this review, together with recent studies devoted to the design of such chelators. This newly emerging range of iron chelators will enable clinicians to apply iron chelation methodology to other disease states and to begin to design personalized chelation regimes.

  20. CHELATING LIGANDS: ENHANCERS OF QUALITY AND PURITY ...

    African Journals Online (AJOL)

    Nwokem et al.

    ABSTRACT. The quality of biogas depends largely on the percentage of methane and hydrogen sulphide gas present. High concentration of hydrogen sulphide results in low quality biogas. This work employed the use of chelating ligands in scrubbing hydrogen sulphide gas while improving the yield of methane gas.

  1. Chelates for Micronutrient Nutrition among Crops

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 8; Issue 7. Chelates for Micronutrient Nutrition among Crops. B S Sekhon. General Article Volume 8 Issue 7 July 2003 pp 46-53. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/008/07/0046-0053. Keywords.

  2. Isolation of an Eleven-Atom Polydentate Carbon-Chain Chelate Obtained by Cycloaddition of a Cyclic Osmium Carbyne with an Alkyne.

    Science.gov (United States)

    Zhu, Congqing; Zhu, Jun; Zhou, Xiaoxi; Zhu, Qin; Yang, Yuhui; Wen, Ting Bin; Xia, Haiping

    2018-03-12

    Carbon ligands have long played an important role in organometallic chemistry. However, previous examples of all-carbon chelating ligands are limited. Herein, we present a novel complex with an eleven-atom carbon chain as a polydentate chelating ligand. This species was formed by the [2+2+2] cycloaddition reaction of two equivalents of an alkyne with an osmapentalyne that contains the smallest carbyne bond angle (127.9°) ever observed. Density functional calculations revealed that electron-donating groups play a key role in the stabilization of this polydentate carbon-chain chelate. This process is also the first [2+2+2] cycloaddition reaction of an alkyne with a late-transition-metal carbyne complex. This study not only enriches the chemistry of polydentate carbon-chain chelates, but also deepens our understanding of the chelating ability of carbon ligands. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Overview of chelation recommendations for thalassaemia and sickle cell disease

    Directory of Open Access Journals (Sweden)

    Banu Kaya

    2014-12-01

    Full Text Available The long term consequences of iron toxicity are mostly reversible with effective iron chelation therapy. Recommendations for use of chelation therapy in transfusion dependent thalassaemia (TDT, sickle cell disease (SCD and non transfusion dependent thalassaemia (NTDT continue to evolve as our knowledge and clinical experience increases. Improved chelation options including drug combinations and a better understanding of condition specific factors may help to improve efficiency of chelation regimens and meet the needs of patients more effectively.

  4. 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.

  5. Reversible immobilization of laccase to poly(4-vinylpyridine) grafted and Cu(II) chelated magnetic beads: biodegradation of reactive dyes.

    Science.gov (United States)

    Bayramoğlu, Gülay; Yilmaz, Meltem; Arica, M Yakup

    2010-09-01

    Poly(4-vinyl pyridine), poly(VP), as a novel metal-chelating fibrous polymer was grafted on the magnetic beads. Poly(4-VP) grafted and/or Cu(II) ions chelated magnetic beads were used for reversible immobilization of Trametes versicolor laccase, and the amounts of immobilized laccase on the beads were determined as 36.8 and 56.4 mg/g beads, respectively. The adsorption of laccase on both modified magnetic beads appeared to follow the Langmuir isotherm model. The degradation of textile dyes with immobilized laccase on the metal chelated magnetic beads was evaluated in a batch system. Three different reactive textile dyes (i.e., Reactive Green 19, Reactive Red 2 and Reactive Brown 10) were successfully degraded in the enzyme reactor. It was observed that the decolorization rate varied widely with chemical structure and types of the substitute group of the reactive dye molecules. (c) 2010 Elsevier Ltd. All rights reserved.

  6. Synergistic effect of chelators and Herbaspirillum sp. GW103 on lead phytoextraction and its induced oxidative stress in Zea mays.

    Science.gov (United States)

    Govarthanan, Muthusamy; Kamala-Kannan, Seralathan; Kim, Seol Ah; Seo, Young-Seok; Park, Jung-Hee; Oh, Byung-Taek

    2016-10-01

    Phytoremediation is an in situ, low-cost strategy for cleanup of the sites contaminated with heavy metals. Experiments were conducted to assess the impact of synthetic chelators and plant growth-promoting rhizosphere bacteria (Herbaspirillum sp. GW103) on heavy metal lead (Pb) uptake in Z. mays cultivated in Pb-contaminated soil. The present study investigated the Pb phytoaccumulation rate and plant antioxidant enzyme activities in Z. mays exposed to 100 mg/kg of PbNO3. The combination of gluconic acid (GA) with Herbaspirillum sp. GW103 treatment showed higher Pb solubility (18.9 mg/kg) compared with other chelators. The chemical chelators showed the significant difference in phytoaccumulation as well as antioxidant enzyme activities. The antioxidant enzymes such as catalase, peroxidase and superoxide dismutase activities changed under Pb stress. The study indicated that increased activity of antioxidant enzymes may play as signal inducers to fight against Pb.

  7. 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.

  8. 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 2M hydrochloric acid by this resin is discussed. Conditions for the quantitative extraction and back-extraction of 9 ions are reported. The results are compared with work on solvent extraction with N-phenylbenzohydroxamic acid. Procedures for attaching N-methyl and N-substituted 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

  9. 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

  10. 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...

  11. Neurotoxicity of metals.

    Science.gov (United States)

    Caito, Samuel; Aschner, Michael

    2015-01-01

    Metals are frequently used in industry and represent a major source of toxin exposure for workers. For this reason governmental agencies regulate the amount of metal exposure permissible for worker safety. While essential metals serve physiologic roles, metals pose significant health risks upon acute and chronic exposure to high levels. The central nervous system is particularly vulnerable to metals. The brain readily accumulates metals, which under physiologic conditions are incorporated into essential metalloproteins required for neuronal health and energy homeostasis. Severe consequences can arise from circumstances of excess essential metals or exposure to toxic nonessential metal. Herein, we discuss sources of occupational metal exposure, metal homeostasis in the human body, susceptibility of the nervous system to metals, detoxification, detection of metals in biologic samples, and chelation therapeutic strategies. The neurologic pathology and physiology following aluminum, arsenic, lead, manganese, mercury, and trimethyltin exposures are highlighted as classic examples of metal-induced neurotoxicity. © 2015 Elsevier B.V. All rights reserved.

  12. The iron chelating agent, deferoxamine detoxifies Fe(Salen-induced cytotoxicity

    Directory of Open Access Journals (Sweden)

    Masanari Umemura

    2017-08-01

    Full Text Available Iron-salen, i.e., μ-oxo-N,N′-bis(salicylideneethylenediamine iron (Fe(Salen was a recently identified as a new anti-cancer compound with intrinsic magnetic properties. Chelation therapy has been widely used in management of metallic poisoning, because an administration of agents that bind metals can prevent potential lethal effects of particular metal. In this study, we confirmed the therapeutic effect of deferoxamine mesylate (DFO chelation against Fe(Salen as part of the chelator antidote efficacy. DFO administration resulted in reduced cytotoxicity and ROS generation by Fe(Salen in cancer cells. DFO (25 mg/kg reduced the onset of Fe(Salen (25 mg/kg-induced acute liver and renal dysfunction. DFO (300 mg/kg improves survival rate after systematic injection of a fatal dose of Fe(Salen (200 mg/kg in mice. DFO enables the use of higher Fe(Salen doses to treat progressive states of cancer, and it also appears to decrease the acute side effects of Fe(Salen. This makes DFO a potential antidote candidate for Fe(Salen-based cancer treatments, and this novel strategy could be widely used in minimally-invasive clinical settings.

  13. 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

  14. Comparison of methionine chelated versus sulfate trace minerals on rate and efficiency of gain and pregnancy rates in beef heifers

    Science.gov (United States)

    Objectives of this experiment were to compare rate and efficiency of gain, and conception rates of yearling heifers supplemented with Cu, Zn, and Mn as either metal methionine hydroxy analogue chelated trace minerals (CTM; provided as MINTREX) or the same trace minerals in SO4 form. The experimental...

  15. 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.

  16. Lipophilic aroylhydrazone chelator HNTMB and its multiple effects on ovarian cancer cells

    Directory of Open Access Journals (Sweden)

    Singh Rakesh K

    2010-02-01

    Full Text Available Abstract Background Metal chelators have gained much attention as potential anti-cancer agents. However, the effects of chelators are often linked solely to their capacity to bind iron while the potential complexation of other trace metals has not been fully investigated. In present study, we evaluated the effects of various lipophilic aroylhydrazone chelators (AHC, including novel compound HNTMB, on various ovarian cancer cell lines (SKOV-3, OVCAR-3, NUTU-19. Methods Cell viability was analyzed via MTS cytotoxicity assays and NCI60 cancer cell growth screens. Apoptotic events were monitored via Western Blot analysis, fluorescence microscopy and TUNEL assay. FACS analysis was carried out to study Cell Cycle regulation and detection of intracellular Reactive Oxygen Species (ROS Results HNTMB displayed high cytotoxicity (IC50 200-400 nM compared to previously developed AHC (oVtBBH, HNtBBH, StBBH/206, HNTh2H/315, HNI/311; IC50 0.8-6 μM or cancer drug Deferoxamine, a hexadentate iron-chelator (IC50 12-25 μM. In a NCI60 cancer cell line screen HNTMB exhibited growth inhibitory effects with remarkable differences in specificity depending on the cell line studied (GI50 10 nM-2.4 μM. In SKOV-3 ovarian cancer cells HNTMB treatment led to chromatin fragmentation and activation of the extrinsic and intrinsic pathways of apoptosis with specific down-regulation of Bcl-2. HNTMB caused delayed cell cycle progression of SKOV-3 through G2/M phase arrest. HNTMB can chelate iron and copper of different oxidation states. Complexation with copper lead to high cytotoxicity via generation of reactive oxygen species (ROS while treatment with iron complexes of the drug caused neither cytotoxicity nor increased ROS levels. Conclusions The present report suggests that both, non-complexed HNTMB as a chelator of intracellular trace-metals as well as a cytotoxic HNTMB/copper complex may be developed as potential therapeutic drugs in the treatment of ovarian and other

  17. Effects of lipopolysaccharide and chelator on mercury content in the cerebrum of thimerosal-administered mice.

    Science.gov (United States)

    Minami, Takeshi; Oda, Keisuke; Gima, Naoya; Yamazaki, Hideo

    2007-11-01

    Thimerosal is one of the best-known preservative agents for vaccines in the world but a relationship between its use and autism has long been suspected so that its effects on the brain need more detailed research. We here examined the influence of lipopolysaccharide injury to the blood-brain barrier on the penetration of mercury from thimerosal into mouse cerebrums, as well as the effect of chelator of heavy metals on cerebrum mercury content. Mercury can be expected to be detected in the cerebrum of normal mice, because the metal is present in standard mouse chow. When 60μg/kg of thimerosal was subcutaneously injected into the mouse, the mercury content in the cerebrum was significantly higher 48h after the thimerosal injection with a maximum peak after 72h. In addition, mercury content in the cerebrum was still higher on day 7 than in the control group. When lipopolysaccharide was pre-injected into mice to induce damage on blood-brain barrier, the mercury content in the cerebrum was significantly higher at 24 and 72h after the injection of 12μg/kg of thimerosal compared to the control group, this dose alone does not cause any increase. The mercury content in the cerebrums of mice was decreased to the control group level on day 7 when a chelator, dimercaprol, was administered once a day from days 3 to 6 after a 60μg/kg, s.c. injection. In addition, d-penicillamine as a chelator decreased the mercury contents in the cerebrum after the high dose administration. In conclusion, a physiological dose of thimerosal did not increase the content of mercury in the cerebrum, but levels were increased when damage to the blood-brain barrier occurred in mice injected with thimerosal. In addition, a chelator of heavy metals may be useful to remove mercury from the cerebrum. Copyright © 2007 Elsevier B.V. All rights reserved.

  18. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Hitoshi; Saitoh, Takashi; Yotsuyanagi, Takao [Tohoku Univ., Sendai (Japan). Faculty of Engineering

    1995-02-01

    Some photophysical data including emission lifetimes ({tau}), total emission quantum yields ({Phi}), 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{sub 1} and the metal-center f-f levels are proposed. The {tau} values of Tb(III)-BAPTA chelates are 1.73 ms in H{sub 2}O and 3.44 ms in D{sub 2}O. The Eu(III)-Quin 2 chelate system shows a bi-exponential decay of emission; {tau}=0.048 and 0.20 ms in H{sub 2}O and 0.066 and 1.44 ms in D{sub 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 {Phi} 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).

  20. Synthesis, characterization and in vitro anticancer evaluations of two novel derivatives of deferasirox iron chelator.

    Science.gov (United States)

    Salehi, Samie; Saljooghi, Amir Sh; Shiri, Ali

    2016-06-15

    Iron (Fe) chelation therapy was initially designed to alleviate the toxic effects of excess Fe evident in Fe-overload diseases. However, the novel toxicological properties of some Fe chelator-metal complexes have shifted significant attention to their application in cancer chemotherapy. The present study investigates the new role of deferasirox as an anticancer agent due to its ability to chelate with iron. Because of aminoacids antioxidant effect, deferasirox and its two novel amino acid derivatives have been synthesized through the treatment of deferasirox with DCC as well as glycine or phenylalanine methyl ester. All new compounds have been characterized by elemental analysis, FT-IR NMR and mass spectrometry. Therefore, the cytotoxicity of these compounds was screened for antitumor activity against some cell lines using cisplatin as a comparative standard by MTT assay and Flow cytometry. The impact of iron in the intracellular generation of reactive oxygen species was assessed on HT29 and MDA-MB-231 cells. The potential of the synthesized iron chelators for their efficacy to protect cells against model oxidative injury induced was compared. The reactive oxygen species intracellular fluorescence intensity were measured and the result showed that the reactive oxygen species intensity after iron incubation increased while after chelators incubation the reactive oxygen species intensity were decreased significantly. Besides, the effect of the synthesized compounds on mouse fibroblast cell line (L929) was simultaneously evaluated as control. The pharmacological results showed that deferasirox and its two novel aminoacid derivatives were potent anticancer agents. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. 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...... or tetrathiomolybdate may be more suitable alternatives today. In copper-toxicity, a free radical scavenger might be recommended as adjuvant to the chelator therapy...

  2. Characterization of new specific copper chelators as potential drugs for the treatment of Alzheimer's disease.

    Science.gov (United States)

    Nguyen, Michel; Robert, Anne; Sournia-Saquet, Alix; Vendier, Laure; Meunier, Bernard

    2014-05-26

    The non-controlled redox-active metal ions, especially copper, in the brain of patients with Alzheimer disease (AD) should be considered at the origin of the intense oxidative damage in the AD brain. Several bis(8-aminoquinoline) ligands, such as 1 and PA1637, are able to chelate Cu(2+) with high affinity, and are specific chelators of copper with respect to iron and zinc. They are able to efficiently extract Cu(2+) from a metal-loaded amyloid. In addition, these tetradentate ligands are specific for the chelation of Cu(2+) compared with Cu(+). Consequently, the copper ion is easily released from the bis(8-aminoquinoline) ligand under reductive conditions, and can be trapped again by a protein having some affinity for copper such as human serum albumin (HSA) proteins. In addition, the copper is not efficiently released from [Cu(CQ)2] in reductive conditions. The catalytic production of H2O2 by [Cu(2+)-Aβ(1-28)]/ascorbate is inhibited in vitro by the bis(8-aminoquinoline) 1, suggesting that 1 should be able to play a protective role against oxidative damages induced by copper-loaded amyloids. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Effect of a novel chelating agent on defect removal during post-CMP cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jiao, E-mail: hongjiao072095@163.com [School of Electronic Information Engineering, Hebei University of Technology, Tianjin 300130 (China); Tianjin Key Laboratory of Electronic Materials and Devices, Tianjin 300130 (China); Niu, Xinhuan, E-mail: xhniu@hebut.edu.cn [School of Electronic Information Engineering, Hebei University of Technology, Tianjin 300130 (China); Tianjin Key Laboratory of Electronic Materials and Devices, Tianjin 300130 (China); Liu, Yuling; He, Yangang; Zhang, Baoguo; Wang, Juan; Han, Liying; Yan, Chenqi; Zhang, Jin [School of Electronic Information Engineering, Hebei University of Technology, Tianjin 300130 (China); Tianjin Key Laboratory of Electronic Materials and Devices, Tianjin 300130 (China)

    2016-08-15

    Highlights: • The post-CMP cleaning of wafers has become a key step in successful CMP processing. • The polyvinyl alcohol (PVA) brush is the most effective method for post-CMP in situ cleaning. • The chemicals used in this chapter are alkaline. • Emphasis on the effect of the different concentration of the chelating agent on defect removal is provided. • The mechanisms under the post-CMP cleaning process to realize optimum manufacturing conditions were studied. - Abstract: Chemical mechanical polishing (CMP) has become widely accepted for the planarization of device interconnect structures in deep submicron semiconductor manufacturing. However, during CMP process the foreign particles, metal contaminants, and other chemical components are introduced onto the wafer surface, so CMP process is considered as one of the dirtiest process to wafer surface defects which may damage the GLSI patterns and the metallic impurities can induce many crystal defects in wafers during the following furnace processing. Therefore, the post-CMP cleaning of wafers has become a key step in successful CMP process and the polyvinyl alcohol (PVA) brush cleaning is the most effective method for post-CMP in situ cleaning. In this study, the effect of the chelating agent with different concentrations on defect removal by using PVA brush cleaning was discussed emphatically. It can be seen from the surface images obtained by scanning electron microscopy and KLA digital comparison system analysis confirmed that the chelating agent can effectively act on the defect removal.

  4. A Study on the Cocktail of Chelating Ligands for Supercritical CO2 Extraction

    International Nuclear Information System (INIS)

    Koh, Moon Sung; Kim, Mun Soo; Joo, Bok Young; Park, Kwang Heon; Kim, Hak Won; Kim, Hong Doo

    2005-01-01

    Solvent extraction of metal ions is a technically important and also well-established process that is used in the chemical and hydrometallurgical industries. Conventional solvent extraction techniques need a large amount of organic solvents and often create environmental problems. Nowadays, more environment-friendly technology is needed, and there has been increasing attention to extracting metal ions by supercritical fluid extraction. CO 2 has become one of the most notable alternative organic solvents due to its nonflammable, nontoxic, nonpolluting, and relatively inexpensive properties: it also has a moderate critical point (73.8 bar, 31.06 .deg. C). Many works have been reported in metal extraction under the supercritical CO 2 (Sc-CO 2 ) solvent. Most of the contaminated substrates are mixed with various nuclides and forms, but chelating ligands developed until now generally extract selectively for metal ions. In this paper, we studied a cocktail of chelating ligands and the extraction of mixed metal ions in Sc-CO 2

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.'

  10. 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.

  11. Chelated ruthenium catalysts for Z-selective olefin metathesis.

    Science.gov (United States)

    Endo, Koji; Grubbs, Robert H

    2011-06-08

    We report the development of ruthenium-based metathesis catalysts with chelating N-heterocyclic carbene (NHC) ligands that catalyze highly Z-selective olefin metathesis. A very simple and convenient procedure for the synthesis of such catalysts has been developed. Intramolecular C-H bond activation of the NHC ligand, promoted by anion ligand substitution, forms the appropriate chelate for stereocontrolled olefin metathesis.

  12. Comparison of simple and chelated amberlite IR-120 for ...

    African Journals Online (AJOL)

    In the present study, the efficiency of simple and chelating Amberlite IR-120 with α-nitroso β-naphthol (IR-αNβN) and with 8-hydroxy quinoline (IR-8HQ) has been compared for the removal of Cu(II) from aqueous solutions. The chelation was confirmed using different characterization techniques like SEM, TGA and FTIR.

  13. The investigation of germanium based compounds, transition metals and isoflavones within foods

    OpenAIRE

    Dowling, Stephen

    2010-01-01

    The body of work here looks not only at how germanium was present in foods but also the ascertainment of chelation behaviour of germanium compounds and also transition metals with flavonoids. The chelation of germanium with flavonoids, or particularly isoflavones, is a completely novel area and gave some interesting results for chelation with isoflavones with transition metals, an area of research that was completely underexploited until recently. (refer to appendix 1) The Fourier Tran...

  14. 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.

  15. Investigation of metal–flavonoid chelates and the determination of flavonoids via metal–flavonoid complexing reactions

    Directory of Open Access Journals (Sweden)

    DUSAN MALESEV

    2007-10-01

    Full Text Available Flavonoids constitute a large group of polyphenolic phytochemicals with antioxidant properties which are overwhelmingly exerted through direct free radical scavenging. Flavonoids also exhibit antioxidant properties through chelating with transition metals, primarily Fe(II, Fe(III and Cu(II, which participate in reactions generating free radicals. Metal–flavonoid chelates are considerably more potent free radical scavengers than the parent flavonoids and play a prominent role in protecting from oxidative stress. To unravel the origin of their potent biological action extensive physico–chemical studies were undertaken to reveal the chemical structure, chelation sites, assess the impact of the metal/ligand ratio on the structure of the complexes and the capacity of flavonoids to bind metal ions. In spite of such extensive efforts, data on the composition, structure and complex-formation properties are incomplete and sometimes even contradictory. The aim of this paper is to give a personal account on the development of the field through a retrospective evaluation of our own research which covers approximately 40 complexes of flavonoids from different flavonoids subclasses (rutin, quercetin, 3-hydroxyflavone, morin and hesperidin with several metal ions or groups and suggest directions for future research. Special emphasis will be given to the site of the central ion, the composition of the complexes, the role of pH in complex formation, the stability of metal–flavonoid complexes and their potential application for analytical purposes.

  16. Treatment of zinc toxicosis in a dog with chelation using d-penicillamine.

    Science.gov (United States)

    Lee, Ye-Rin; Kang, Min-Hee; Park, Hee-Myung

    2016-11-01

    To describe chelation therapy with d-penicillamine for treatment of zinc toxicosis in a dog. A 1.5-year-old intact female Maltese dog weighing 2.7 kg was presented with acute, progressive anorexia, lethargy, pigmenturia, and melena. The owner reported that the dog had ingested a hook from a dog leash made of a zinc-based alloy 9 days prior. A blood transfusion was administered and an abdominal radiograph revealed a metal-dense foreign body in the stomach. Laboratory findings revealed a serum zinc concentration of 1845.12 μg/dL (reference interval, 70-200 μg/dL) and a decreased hematocrit that remained low despite removal of the zinc foreign body. On day 3, another blood transfusion was performed and d-penicillamine therapy was instituted. After the administration of d-penicillamine, the clinical signs and hemogram progressively improved and the dog was discharged 2 days later. On day 9 after initial presentation, the hematocrit and platelet values were within normal limits and the serum zinc concentration was 280.16 μg/dL. This case demonstrates the use of d-penicillamine in the treatment of zinc toxicosis. Serum zinc concentration appeared to decline more rapidly after administration of d-penicillamine than before chelation therapy. This is the first report to evaluate serial serum zinc concentrations before and during chelation therapy with d-penicillamine. © Veterinary Emergency and Critical Care Society 2015.

  17. 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)

  18. 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).

  19. A detailed in vitro study of naproxen metal complexes in quest of ...

    African Journals Online (AJOL)

    Results: The Naproxen metal chelates showed significant anti-inflammatory effects in dose dependent manner. Naproxen standard showed maximum inhibition occurred 73.21% at the dose of 2000 lg/ml. Among Naproxen metal chelates, Naproxen silver complex showed potent antimicrobial activity against most of the ...

  20. 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.

  1. Distributions of uranium adsorbed from seawater in spherical polyacrylamidoxime chelating resins

    International Nuclear Information System (INIS)

    Katoh, Shunsaku; Sugasaka, Kazuhiko; Hirotsu, Takahiro; Takai, Nobuharu; Itagaki, Takaharu; Ouchi, Hidenaga.

    1984-01-01

    Distributions of metals adsorbed from seawater in spherical polyacrylamidoxime chelating resins were measured by X-ray micro-analyzer. Distributions of uranium in adsorbents were different according to their gel structure or porosity. In the case of adsorbents with low swelling tendencies, uranium was adsorbed only in the superficial layers of the adsorbents. The amount of adsorbed uranium increased with increasing of contact time, but no uranium was detected in the center of adsorbent even after 331 days. Iron was adsorbed only in the surface layer. Magnesium was detected almost uniformly in all parts of adsorbent. Copper and zinc were detected very little. (author)

  2. Extraction of chromium, copper, and arsenic from CCA-treated wood using biodegradable chelating agents.

    Science.gov (United States)

    Ko, Chun-Han; Chen, Pin-Jui; Chen, Shu-Hui; Chang, Fang-Chih; Lin, Far-Ching; Chen, Ke-Kung

    2010-03-01

    The aim of this study was to investigate the biodegradable chelating agents S,S-ethylenediaminedisuccinic acid (SS-EDDS) and nitrilotriacetic acid (NTA) as potential alternatives and compare them with ethylenediaminetetraacetic acid (EDTA) for effectiveness. Extraction of heavy metals from chromated copper arsenate (CCA)-treated wood with EDDS, NTA, or EDTA solvent was evaluated at various solvent pH levels and stoichiometric ratios. Based on the present data, the recommended extraction conditions are pH 4.0 and EDDS-CCA stoichiometric ratios of 10. 2009 Elsevier Ltd. All rights reserved.

  3. Removal of Cu(II) and Cr(VI) ions from aqueous solution using chelating fiber packed column: equilibrium and kinetic studies.

    Science.gov (United States)

    Ko, Young Gun; Chun, Yong Jin; Kim, Choong Hyun; Choi, Ung Su

    2011-10-30

    Herein, we demonstrate the adsorption process system with the diethylenetriamne coupled polyacrylonitrile fiber for the removal of Cu(II) and Cr(VI) ions in the aqueous solution. The synthesized chelating fiber showed a high adsorption capacity of 11.4 mequiv/g. Interestingly, the crystal growth of copper ions on the chelating fiber was observed during the adsorption process. The chelating fiber packed column showed the high performance of the removal of Cu(II) in the aqueous solution due to the distinct characteristic of the crystal growth of metal ions on the chelating fiber. After Cu(II) adsorption on the chelating fiber, the color of the fiber changed to light blue from yellow. The isotherm parameter n of 1.991 was obtained with Freundlich isotherm model for the adsorption equilibrium study which indicates that Cu(II) adsorption on the chelating fiber is very favorable due to n>1. The pseudo-first-order and pseudo-second-order model equations were used for the kinetic study. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Effect of pH on the release of radionuclides and chelating agents from cement-solidified decontamination ion-exchange resins collected from operating nuclear power stations

    Energy Technology Data Exchange (ETDEWEB)

    McIsaac, C.V.; Akers, D.W.; McConnell, J.W. (EG and G Idaho, Inc., Idaho Falls, ID (USA))

    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.

  5. 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

  6. COMPARISON OF SIMPLE AND CHELATED AMBERLITE IR-120 ...

    African Journals Online (AJOL)

    13] have also been used. Many chelating ligands such as quinolone, ... synthesized by covalent bonds are much more resistant to external effects than those by simple adsorption [15]. Amberlite IR-120, a vinyl benzene polymer has good ...

  7. Chelation of di- and trivalent iron with some polyaminopolycarboxylic acids

    International Nuclear Information System (INIS)

    Hafez, M.B.; Sharabi, Nahid; Patti, Francois.

    1979-02-01

    The chelation of di- and trivalent iron with some polyaminopolycarboxylic acids was studied. The influence of pH on the formation of the complex was investigated, the molecular ratio and the stability constants were determined [fr

  8. Cell assay using a two-photon-excited europium chelate.

    Science.gov (United States)

    Xiao, Xudong; Haushalter, Jeanne P; Kotz, Kenneth T; Faris, Gregory W

    2011-08-01

    We report application of two-photon excitation of europium chelates to immunolabeling of epidermal growth factor receptor (EGFR) cell surface proteins on A431 cancer cells. The europium chelates are excited with two photons of infrared light and emit in the visible. Europium chelates are conjugated to antibodies for EGFR. A431 (human epidermoid carcinoma) cells are labeled with this conjugate and imaged using a multiphoton microscope. To minimize signal loss due to the relatively long-lived Eu(3+) emission, the multiphoton microscope is used with scanning laser two-photon excitation and non-scanning detection with a CCD. The chelate labels show very little photobleaching (less than 1% during continuous illumination in the microscope for 20 minutes) and low levels of autofluorescence (less than 1% of the signal from labeled cells). The detection limit of the europium label in the cell assay is better than 100 zeptomoles.

  9. Chelated Ruthenium Catalysts for Z-Selective Olefin Metathesis

    OpenAIRE

    Endo, Koji; Grubbs, Robert H.

    2011-01-01

    We report the development of ruthenium-based metathesis catalysts with chelating N-heterocyclic carbene (NHC) ligands which catalyze highly Z-selective olefin metathesis. A very simple and convenient synthetic procedure of such a catalyst has been developed. An intramolecular C-H bond activation of the NHC ligand, which is promoted by anion ligand substitution, forms the appropriate chelate for stereo- controlled olefin metathesis.

  10. 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)

  11. Iron Chelation Adherence to Deferoxamine and Deferasirox in Thalassemia

    Science.gov (United States)

    Trachtenberg, Felicia; Vichinsky, Elliott; Haines, Dru; Pakbaz, Zahra; Mednick, Lauren; Sobota, Amy; Kwiatkowski, Janet; Thompson, Alexis A.; Porter, John; Coates, Thomas; Giardina, Patricia J.; Olivieri, Nancy; Yamashita, Robert; Neufeld, Ellis J.

    2015-01-01

    The Thalassemia Clinical Research Network collected adherence information from 79 patients on deferoxamine and 186 on deferasirox from 2007 to 2009. Chelation adherence was defined as percent of doses administered in the last 4 weeks (patient report) out of those prescribed (chart review). Chelation history since 2002 was available for 97 patients currently on deferoxamine and 217 on deferasirox, with crude estimates of adherence from chart review. Self-reported adherence to both deferoxamine and deferasirox were quite high, with slightly higher adherence to the oral chelator (97 vs. 92%). Ninety percent of patients on deferasirox reported at least 90% adherence, compared with 75% of patients on deferoxamine. Adherence to both chelators was highest in children, followed by adolescents and older adults. Predictors of lower deferoxamine adherence were smoking in the past year, problems sticking themselves (adults only), problems wearing their pump, and fewer transfusions in the past year. Predictors of lower deferasirox adherence were bodily pain and depression. Switching chelators resulted in increased adherence, regardless of the direction of the switch, although switching from deferoxamine to deferasirox was far more common. As adherence to deferoxamine is higher than previously reported, it appears beneficial for patients to have a choice in chelators. PMID:21523808

  12. Assessing the Impact of EDTA Chelating Effect on some Macro- and Microminerals in Prussian Carp (Carassius Gibelio Tissues

    Directory of Open Access Journals (Sweden)

    Marioara Nicula

    2011-10-01

    Full Text Available Chelators are used in chemical analysis, in medical aplications, as water softeners, as decontamination agents on radioactive surfaces and they are ingredients in many commercial products such as shampoos and food preservatives. Such a synthetic chelator is EDTA (ethylenediaminetetraacetic acid. It is considered one of the tools that promises to control the heavy metal pollution in aquaculture. EDTA attaches itself to heavy metals and carries the metals from the fish body. EDTA can also slow free-radical activity produced by heavy metals in the body. Because its ability to sequester metal ions, we tried to estimate the potential risks of a chronic exposure to EDTA on tissue mobilization of some metals which have an essential role in realization of different cell functions in Prussian carp specimens. Ca, Mg, Fe, Zn. Mn and Cu, were the mineral elements we have targeted in this study. It was found that these minerals have a trend of their tissues distribution and concentration in the body of the control specimens (higher or lower related to other similar works and EDTA presence in water led to a significant decreasing of their level in all tissues analyzed in a dose-dependent manner.

  13. 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...

  14. Synthesis of aminobenzyltriethylenetetraaminohexaacetic acid: conjugation of the chelator to protein by an alkylamine linkage.

    Science.gov (United States)

    Bhargava, K K; Zhang, Z Y; Palestro, C J; Acharya, S A

    1999-10-01

    The conjugation of a chelating agent to an antibody as an anchoring site for a radionuclide is the first step in the successful preparation of a radiolabeled antibody for a diagnostic and therapeutic application. The high affinity of the protein bound chelator towards radionuclide ensures a higher selectivity in the delivery of the radionuclide to the targeted tissue. 4-Aminobenzylderivativetriethlenetetraaminohexaacetic acid (TTHA), a hexadentate chelating agent has been now prepared for conjugation with proteins in view of the higher affinity of TTHA metal ions as compared to DTPA. The latent crosslinking potential of alpha-hydroxy aldehydes has been used to conjugate the new chelating agent to proteins through an alkylamine linkage. On incubation of amino benzyl TTHA with glycoladehyde at neutral pH and room temperature, the reagent is converted to oxo ethyl amino benzyl TTHA. On addition of albumin to this reaction mixture, the oxo ethylamino benzyl TTHA generates reversible schiff base adducts with the amino groups of albumin. The reduction of the Schiff base adducts of the chelator with the protein by sodium cyanoborohydride stabilizes the schiff base adducts as stable alkylamine linkages. 4-Thiocyanatobenzyl TTHA has also been prepared and conjugated to albumin through a thiocarbamoyl linkage. Both preparations of TTHA conjugated albumin complexed with 99mTc and 111In, with high affinity and no decomposition of the complex was noticed for at least up to 6 hrs after the preparation. The radiolabels complexed with these TTHA -albumin conjugates could not be 'chased' out by free DTPA. A comparison of the biodistribution of 111In, bound to the TTHA conjugated through an alkylamine and a thiocarbamoyl linkage showed that 111In complexed with alkylamine linked TTHA was retained in blood to a level nearly 17% higher compared to that seen with thicarbamoyl linked TTHA, one hr after the injection into mice. Thus, the alkylamine linkage appears to be more stable under

  15. 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

  16. Chelation-Assisted, Copper(II) Acetate-Accelerated Azide-Alkyne Cycloaddition

    Science.gov (United States)

    Kuang, Gui-Chao; Michaels, Heather A.; Simmons, J. Tyler; Clark, Ronald J.; Zhu, Lei

    2010-01-01

    We described in a previous communication (ref. 13) a variant of the popular CuI-catalyzed azide-alkyne cycloaddition (AAC) process where 5 mol% Cu(OAc)2 in the absence of any added reducing agent is sufficient to enable the reaction. 2-Picolylazide (1) and 2-azidomethylquinoline (2) were found to be by far the most reactive carbon azide substrates that convert to 1,2,3-triazoles in as short as a few minutes under the discovered conditions. We hypothesized that the abilities of 1 and 2 to chelate CuII contribute significantly to the observed high reaction rates. The current work examines the effect of auxiliary ligands near the azido group other than pyridyl for CuII on the efficiency of the Cu(OAc)2-accelerated AAC reaction. The carbon azides capable of binding to the catalytic copper center at the alkylated azido nitrogen in a chelatable fashion were indeed shown to be superior substrates under the reported conditions. The chelation between carbon azide 11 and CuII was demonstrated in an X-ray single crystal structure. In a limited set of examples, the ligand tris(benzyltriazolylmethyl)amine (TBTA), developed by Fokin et al. for assisting the original CuI-catalyzed AAC reactions (ref. 8), also dramatically enhances the Cu(OAc)2-accelerated AAC reactions involving non-chelating azides. This observation leads to the hypothesis of an additional effect of chelating azides on the efficiencies of Cu(OAc)2-accelerated AAC reactions, which is to facilitate the rapid reduction of CuII to highly catalytic CuI species. Mechanistic studies on the AAC reactions with particular emphasis on the role of carbon azide/copper interactions will be conducted based on the observations reported in this work. Finally, the immediate utility of the product 1,2,3-triazole molecules derived from chelating azides as multidentate metal coordination ligands is demonstrated. The resulting triazolyl-containing ligands are expected to bind with transition metal ions via the N(2) nitrogen of the 1

  17. 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

  18. Extraction of actinides and fission products ions by non-chelating N,N'-tetraalkyldiamides

    International Nuclear Information System (INIS)

    Charbonnel, M.C.; Musikas, C.

    1986-09-01

    N,N-dialkylmonoamides, are good extractants of metallic ions. They were considered as alternative to TBP in nuclear fuels reprocessing. The present paper deals with the extractive properties of N,N'-tetrabutylglutaramide. N,N'-tetraalkyldiamides of dicarboxylic acids except malonamides do not extract the trivalent actinides and lanthanides from aqueous HNO, solutions probably because there is no favourable ligand conformation to chelate the metallic ions. This feature is interesting for the nuclear fuel reprocessing since the presence of a second amide group could lead to new selectivities and to radiolytic and solvolytic degradation products easier to handle. We will present the investigation results of HNO 3 U(VI), Pu(IV) and fission products extraction by TBGA in toluene from HNO 3 aqueous solution. 5 figs, 6 refs

  19. 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

  20. 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.

  1. Recovering Ga(III) from coordination complexes using pyridine 2,6-dicarboxylic acid chelation ion chromatography.

    Science.gov (United States)

    Staff, K; Brown, M B; Hider, R C; Kong, X L; Friden, P; Jones, S A

    2010-09-01

    Ion exchange chelation chromatography is an effective means to extract metals from coordination complexes and biological samples; however there is a lack of data to verify the nature of metal complexes that can be successfully analysed using such a procedure. The aim of this study was to assess the capability of pyridine 2,6-dicarboxylic acid (PDCA) to extract and quantify Ga(III) from a range of environments using standard liquid chromatography apparatus. The PDCA chelation method generated a single Ga(III) peak with a retention time of 2.55 +/- 0.02 min, a precision of PDCA assay extracted 96.9 +/- 1.2% of the spiked Ga(III) from porcine mucus and 100.7 +/- 2.7% from a citrate complex (stability constant 10.02), but only ca 50% from an EDTA complex (stability constant 22.01). These data suggest that PDCA chelation can be considered a suitable alternative to inductively coupled plasma mass spectrometry for Ga(III) quantification from all but the most strongly bound coordinated complexes i.e. a stability constant of <15. 2010 John Wiley & Sons, Ltd.

  2. To chelate or not to chelate in MDS: That is the question!

    Science.gov (United States)

    Zeidan, Amer M; Griffiths, Elizabeth A

    2018-03-08

    Myelodysplastic syndromes (MDS) are a heterogeneous group of hemopathies that exhibit physical manifestations with clinical consequences of bone marrow failure and inherent risk of progression to acute myeloid leukemia. Iron overload (IO) is common in MDS due to chronic transfusion support and disease-related alterations in iron metabolism. IO has been conclusively associated with inferior outcomes among MDS patients. Despite lack of randomized trials showing a survival impact of iron chelation therapy (ICT), ICT is recommended by experts and guidelines for select MDS patients with IO and is often used. The availability of effective oral ICT agents has reignited the controversy regarding ICT use in patients with MDS and IO. Here we summarize the studies evaluating the value of ICT in MDS and suggest a practical approach for use of these therapies. We also highlight controversies regarding use of ICT in MDS and discuss some ongoing efforts to answer these questions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. 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.

  4. 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

  5. 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...

  6. 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)

  7. 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.

  8. Inositol hexa-phosphate: a potential chelating agent for uranium

    Energy Technology Data Exchange (ETDEWEB)

    Cebrian, D.; Tapia, A.; Real, A.; Morcillo, M.A. [Radiobiology Laboratory, Radiation Dosimetry Unit, Department of Environment, CIEMAT, Avda Complutense 22, 28040 Madrid (Spain)

    2007-07-01

    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)

  9. 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)

  10. 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.

  11. 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

  12. Heavy metal ion uptake properties of polystyrene-supported ...

    Indian Academy of Sciences (India)

    Metal ion uptake properties of polystyrene-supported chelating polymer resins functionalized with (i) glycine, (ii) hydroxy benzoic acid, (iii) Schiff base and (iv) diethanol amine have been investigated. The effects of pH, time and initial concentration on the uptake of metal ions have been studied. The uptake of metal ion ...

  13. 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

  14. Lauriston S. Taylor Lecture: the quest for therapeutic actinide chelators.

    Science.gov (United States)

    Durbin, Patricia W

    2008-11-01

    All of the actinides are radioactive. Taken into the body, they damage and induce cancer in bone and liver, and in the lungs if inhaled, and U(VI) is a chemical kidney poison. Containment of radionuclides is fundamental to radiation protection, but if it is breached accidentally or deliberately, decontamination of exposed persons is needed to reduce the consequences of radionuclide intake. The only known way to reduce the health risks of internally deposited actinides is to accelerate their excretion with chelating agents. Ethylendiaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) were introduced in the 1950's. DTPA is now clinically accepted, but its oral activity is low, it must be injected as a Ca(II) or Zn(II) chelate to avoid toxicity, and it is structurally unsuitable for chelating U(VI) or Np(V). Actinide penetration into the mammalian iron transport and storage systems suggested that actinide ions would form stable complexes with the Fe(III)-binding units found in potent selective natural iron chelators (siderophores). Testing of that biomimetic approach began in the late 1970's with the design, production, and assessment for in vivo Pu(IV) chelation of synthetic multidentate ligands based on the backbone structures and Fe(III)-binding groups of siderophores. New efficacious actinide chelators have emerged from that program, in particular, octadentate 3,4,3-LI(1,2-HOPO) and tetradentate 5-LIO(Me-3,2-HOPO) have potential for clinical acceptance. Both are much more effective than CaNa3-DTPA for decorporation of Pu(IV), Am(III), U(VI), and Np(IV,V), they are orally active, and toxicity is acceptably low at effective dosage.

  15. 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

  16. Efficacy of chelation therapy to remove aluminium intoxication.

    Science.gov (United States)

    Fulgenzi, Alessandro; De Giuseppe, Rachele; Bamonti, Fabrizia; Vietti, Daniele; Ferrero, Maria Elena

    2015-11-01

    There is a distinct correlation between aluminium (Al) intoxication and neurodegenerative diseases (ND). We demonstrated how patients affected by ND showing Al intoxication benefit from short-term treatment with calcium disodium ethylene diamine tetraacetic acid (EDTA) (chelation therapy). Such therapy further improved through daily treatment with the antioxidant Cellfood. In the present study we examined the efficacy of long-term treatment, using both EDTA and Cellfood. Slow intravenous treatment with the chelating agent EDTA (2 g/10 mL diluted in 500 mL physiological saline administered in 2 h) (chelation test) removed Al, which was detected (using inductively coupled plasma mass spectrometry) in urine samples collected from patients over 12 h. Patients that revealed Al intoxication (expressed in μg per g creatinine) underwent EDTA chelation therapy once a week for ten weeks, then once every two weeks for a further six or twelve months. At the end of treatment (a total of 22 or 34 chelation therapies, respectively), associated with daily assumption of Cellfood, Al levels in the urine samples were analysed. In addition, the following blood parameters were determined: homocysteine, vitamin B12, and folate, as well as the oxidative status e.g. reactive oxygen species (ROS), total antioxidant capacity (TAC), oxidized LDL (oxLDL), and glutathione. Our results showed that Al intoxication reduced significantly following EDTA and Cellfood treatment, and clinical symptoms improved. After treatment, ROS, oxLDL, and homocysteine decreased significantly, whereas vitamin B12, folate and TAC improved significantly. In conclusion, our data show the efficacy of chelation therapy associated with Cellfood in subjects affected by Al intoxication who have developed ND.

  17. Biodegradation of synthetic chelates in subsurface sediments from the southeast coastal plain

    Energy Technology Data Exchange (ETDEWEB)

    Bolton, H. Jr.; Li, S.W.; Workman, D.J.; Girvin, D.C. (Pacific Northwest Lab., Richland, WA (United States))

    The codisposal of synthetic chelating agents [e.g., ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and nitrilotriacetic acid (NTA)] and radionuclides has been implicated in increased radionuclide transport in the subsurface environment. Microbial transformations of chelates in the subsurface are currently unknown, but could influence chelate persistence and thus alter the transport of radionuclides. Surface soil and subsurface sediments from five formations (36- to 376-m depth) were collected near Allendale, SC. Aerobic mineralization of [sup 14]C-labeled EDTA, DTPA, and NTA occurred in select sediments indicating that subsurface microorganisms can degrade chelates, whereas chelates may be relatively stable in strata where limited mineralization occurred. The chelates were not mineralized more rapidly or to a greater extent in the surface soil than in the subsurface sediments. The relative order of chelate persistence was EDTA > DTPA > NTA, with the maximum amount mineralized during 115 d at 15, 26, and 43%, respectively. Maximum mineralization of all three chelates did not occur in the same sediment, indicating that different microbial populations were responsible for the degradation of each chelate. Mineralization of chelates was minimal under denitrifying conditions and was reduced when additional soluble C was added. There was no relationship between chelate mineralization and the adsorption of chelates to sediments or the aqueous speciation of the chelates. 47 refs., 4 figs., 3 tabs.

  18. High-affinity recognition of lanthanide(III) chelate complexes by a reprogrammed human lipocalin 2.

    Science.gov (United States)

    Kim, Hyun Jin; Eichinger, Andreas; Skerra, Arne

    2009-03-18

    Human lipocalin 2 (Lcn2), also known as neutrophil gelatinase-associated lipocalin (NGAL), which naturally scavenges bacterial ferric siderophores, has been engineered to specifically bind rare-earth and related metal ions as chelate complexes with [(R)-2-amino-3-(4-aminophenyl)propyl]-trans-(S,S)-cyclohexane-1,2-diaminepentaacetic acid (p-NH(2)-Bn-CHX-A''-DTPA). To this end, 12 amino acid residues in the ligand pocket of Lcn2, which is formed by four loops at the open end of an eight-stranded beta-barrel, were subjected to targeted random mutagenesis, and from the resulting library, variants with binding activity for the Me x DTPA group were selected using the method of bacterial phage display. One promising candidate was further developed in several cycles of in vitro affinity maturation using partial random mutagenesis and selection (via phage display and/or Escherichia coli colony screening) under conditions of increasing stringency. As result, an Lcn2 variant was obtained that binds Y x DTPA with a dissociation constant as low as 400 pM. The Lcn2 variant specifically recognizes the artificial ligand, as exemplified in (competitive) ELISA and real-time surface plasmon resonance analyses. DTPA-complexed Y(3+), Tb(3+), Gd(3+), and Lu(3+) are most tightly bound, comprising metal ions whose isotopes are in common use for radiotherapy and imaging. All of the Lcn2 variants are stably folded and can be functionally produced in high yield in E. coli. X-ray crystallographic analyses show that the new ligand is well-accommodated in the central cavity of the engineered lipocalin, whose fold is largely preserved, but that the mode of binding differs from the one seen with the natural ligand Fe x enterobactin. This structural study reveals analogies but also differences with respect to previously described antibody-metal chelate complexes. Notably, the functionalized side chain of DTPA protrudes from the ligand pocket of the lipocalin in such a way that its conjugates (with

  19. Mechanisms for chelator stimulation of microbial Fe(III) -oxide reduction

    Science.gov (United States)

    Lovley, D.R.; Woodward, J.C.

    1996-01-01

    The mechanisms by which nitrilotriacetic acid (NTA) stimulated Fe(III) reduction in sediments from a petroleum-contaminated aquifer were investigated in order to gain insight into how added Fe(III) chelators stimulate the activity of hydrocarbon-degrading, Fe(III)-reducing microorganisms in these sediments, and how naturally occurring Fe(III) chelators might promote Fe(III) reduction in aquatic sediments. NTA solubilized Fe(III) from the aquifer sediments. NTA stimulation of microbial Fe(III) reduction did not appear to be the result of making calcium, magnesium, potassium, or trace metals more available to the microorganisms. Stimulation of Fe(III) reduction could not be attributed to NTA serving as a source of carbon or fixed nitrogen for Fe(III)-reducing bacteria as NTA was not degraded in the sediments. Studies with the Fe(III)-reducing microorganism, Geobacter metallireducens, and pure Fe(III)-oxide forms, demonstrated that NTA stimulated the reduction of a variety of Fe(III) forms, including highly crystalline Fe(III)-oxides such as goethite and hematite. The results suggest that NTA solubilization of insoluble Fe(III)-oxide is an important mechanism for the stimulation of Fe(III) reduction by NTA in aquifer sediments.

  20. Neuroprotective Role of a Novel Copper Chelator against Aβ42 Induced Neurotoxicity

    Directory of Open Access Journals (Sweden)

    Sandeep Kumar Singh

    2013-01-01

    Full Text Available Alzheimer's disease (AD is a progressive neurodegenerative disease and associated with the extracellular deposits of amyloid-β peptide in hippocampus region. Metal ions like Cu, Fe and Zn are known to associate with the amyloid beta (Aβ at high concentration and interaction of these ions with soluble and aggregated forms of Aβ peptide help in development of AD. Here we showed Cu mediated neurotoxicity in the eye tissues of transgenic Drosophila expressing human amyloid β and its rescue through a novel Cu chelator. In this context, we have synthesised and characterized the compound L 2,6-Pyridinedicarboxylic acid, 2,6-bis[2-[(4-carboxyphenyl methylene] hydrazide] by Mass spectra (MS and Elemental analysis (EA. The Cu chelation potential of the compound L is tested in vivo in Drosophila. Oral administration of Copper to the transgenic larvae resulted in severe degeneration in eye tissues, which was rescued by the supplementation of compound L. The levels of anti-oxidant markers like SOD and MDA were measured in compound L treated flies and found a significant rescue (P<0.001. Further rescue of the eye degeneration phenotypes as revealed by SEM affirm the role of copper in Aβ toxicity. Hence, use of compound L, an amidoamine derivative, could be a possible therapeutic measure for Aβ induced neurotoxicity.

  1. Iron chelation by deferoxamine prevents renal interstitial fibrosis in mice with unilateral ureteral obstruction.

    Directory of Open Access Journals (Sweden)

    Yasumasa Ikeda

    Full Text Available Renal fibrosis plays an important role in the onset and progression of chronic kidney diseases (CKD. Although several mechanisms underlying renal fibrosis and candidate drugs for its treatment have been identified, the effect of iron chelator on renal fibrosis remains unclear. In the present study, we examined the effect of an iron chelator, deferoxamine (DFO, on renal fibrosis in mice with surgically induced unilateral ureter obstruction (UUO. Mice were divided into 4 groups: UUO with vehicle, UUO with DFO, sham with vehicle, and sham with DFO. One week after surgery, augmented renal tubulointerstitial fibrosis and the expression of collagen I, III, and IV increased in mice with UUO; these changes were suppressed by DFO treatment. Similarly, UUO-induced macrophage infiltration of renal interstitial tubules was reduced in UUO mice treated with DFO. UUO-induced expression of inflammatory cytokines and extracellular matrix proteins was abrogated by DFO treatment. DFO inhibited the activation of the transforming growth factor-β1 (TGF-β1-Smad3 pathway in UUO mice. UUO-induced NADPH oxidase activity and p22(phox expression were attenuated by DFO. In the kidneys of UUO mice, divalent metal transporter 1, ferroportin, and ferritin expression was higher and transferrin receptor expression was lower than in sham-operated mice. Increased renal iron content was observed in UUO mice, which was reduced by DFO treatment. These results suggest that iron reduction by DFO prevents renal tubulointerstitial fibrosis by regulating TGF-β-Smad signaling, oxidative stress, and inflammatory responses.

  2. Effects of detergent formula chelating agents on the metabolism and toxicity of cadmium in mice

    International Nuclear Information System (INIS)

    Engstroem, B.; Nordberg, G.F.

    1978-01-01

    Chelating agents like NTA (nitrilotriacetic acid) STPP (sodiumtripolyphosphate, Na 5 P 3 O 10 ) and EDTA (ethylenediaminetetraacetic acid) are used as components of detergents. An increased toxicity of some metal compounds when combined with NTA has led to decreased use of this chelating agent in relation to STTP. In the present studies short-term effects chelating agents on cadmium toxicity in mice were investigated. I: In the short-term study, mice subcutaneously exposed to CdCl 2 (3.2 mg Cd/kg b.wt) in combination with STPP (32 mg/kg b.wt.)demonstrated a markedly higher mortality compared to animals given CdCl 2 alone. This increase in mortality was similar to the one encountered when CdCl 2 (3.2 mg Cd/kg b.wt.) and NTA (32 mg/kg b.wt.) were combined. Animals exposed subcutaneously to CdCl 2 +STPP or CdCl 2 +NTA showed histological evidence of liver necrosis 24 hrs after exposure not seen in animals given the same dose of CdCl 2 alone and also had markedly lower cadmium concentrations in the livers compared to only CD-exposed animals. II: In the long-term study, mice were exposed orally to CdSO 4 (50 p.p.m CD) alone or in combination with STPP (500 p.p.m.), NTA(500 p.p.m.) or EDTA(50 p.p.m.) by continuous administration via the drinking water for 18 months. A decreased total excretion of urine proteins was seen in all Cd-treated animals irrespectively of the combination with various chelating agents. The conclusion of the present work was that NTA and STPP given by subcutaneous injection to mice markedly increased the toxicity of cadmium but that neither NTA, STPP nor EDTA given orally altered the toxicity of cadmium during a period of long-term exposure of 18 months. (author)

  3. 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

  4. Targeted Iron Chelation Will Improve Recovery after Spinal Cord Injury

    Science.gov (United States)

    2014-10-01

    for glial replacement after mid-thoracic contusion injury or cervical lateral hemi-section injury. Our pilot data reveal that iron levels do not...did not improve open field locomotion (Figure 1B). Intriguingly, rats receiving vehicle (grape juice ) performed significantly worse than those...cord injury in animals given the iron chelator Exjade, vehicle (grape juice ) or nothing (control). A

  5. Iron chelating activity, phenol and flavonoid content of some ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-09-17

    Sep 17, 2008 ... Thalassemia major is characterized by anemia, iron overload, further potentiation of reactive oxygen species (ROS) and damage to major organs, especially the cardiovascular system. Antioxidant and other supportive therapies protect red blood cells (RBC) against antioxidant damage. Chelation therapy.

  6. Ruthenium complexes of chelating amido-functionalized N ...

    Indian Academy of Sciences (India)

    Ruthenium complexes of chelating amido-functionalized N-heterocyclic carbene ligands: Synthesis, structure and DFT studies. SACHIN KUMARa, ANANTHA NARAYANANa, MITTA NAGESWAR RAOa,. MOBIN M SHAIKHb and PRASENJIT GHOSHa,∗. aDepartment of Chemistry and bNational Single Crystal X-ray ...

  7. 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.

  8. Anti-inflammatory activity of some copper chelates

    Energy Technology Data Exchange (ETDEWEB)

    Sorenson, J.R.J.

    1974-01-01

    With the observation that cupric acetate had anti-inflammatory activity in the foot edema model of inflammation, it was felt that copper may play a role as a component of the active metabolite of anti-inflammatory agents used clinically. To test this hypothesis, various Cu chelates were made and tested in the foot edema, cotton-wad granuloma and polyarthritis models of inflammation. A marked increase in anti-inflammatory activity has been observed for the Cu chelates of chelating agents that had no anti-inflammatory activity as well as those that have been used clinically. Since ulcers may be viewed as inflammatory processes and often associated with the arthritic disease syndrome, the Cu chelates were evaluated as anti-ulcer agents. These compounds were demonstrated to have anti-ulcer activity in the Shay as well as the corticoid and stress induced rat ulcer models. Mechanistic considerations relevant to lysosomal and digestive proteolytic enzyme inhibition, anti-cholinergic activity, prostaglandin synthesis and wound healing are discussed. 9 references, 3 figures, 3 tables.

  9. Chelating ligands: enhancers of quality and purity of biogas ...

    African Journals Online (AJOL)

    The quality of biogas depends largely on the percentage of methane and hydrogen sulphide gas present. High concentration of hydrogen sulphide results in low quality biogas. This work employed the use of chelating ligands in scrubbing hydrogen sulphide gas while improving the yield of methane gas. Experimental ...

  10. Chelation of aluminum by combining deferasirox and deferiprone in rats.

    Science.gov (United States)

    Saljooghi, Amir Shokooh

    2012-09-01

    The hypothesis that two known chelators deferasirox and deferiprone (L1) might be more efficient as combined treatment than as single therapies in removing aluminum from the body was tested in a new acute rat model. Seven-week-old male Wistar rats received chelators: deferasirox (orally [p.o.]), L1 (p.o.) or deferasirox + L1 as 100 or 200 mg/kg dose half an hour after a single intraperitoneal administration of 6 mg Al/kg body weight in the form of chloride. Serum aluminum concentration, urinary aluminum and iron excretions were determined by graphite furnace atomic absorption spectrometry. Both chelators were effective only at the higher dose level. While deferasirox was more effective than L1 in enhancing urinary aluminum excretion, L1 was more effective than deferasirox in enhancing urinary iron excretion. In the combined treatment group, deferasirox did not increase the L1 effect on aluminum and L1 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 aluminum chelators. Urinary values were more useful due to the high variability of serum results.

  11. Bone marrow and chelatable iron in patients with protein energy ...

    African Journals Online (AJOL)

    Objectives: To examine the iron status of malnourished children by comparing bone marrow iron deposits in children with protein energy malnutrition with those in well-nourished controls, and measuring chelatable urinary iron excretion in children with kwashiorkor. Design: Bone marrow iron was assessed histologicaHy in ...

  12. Experimental Investigation on the Mechanism of Chelation-Assisted, Copper(II) Acetate-Accelerated Azide-Alkyne Cycloaddition

    Science.gov (United States)

    Kuang, Gui-Chao; Guha, Pampa M.; Brotherton, Wendy S.; Simmons, J. Tyler; Stankee, Lisa A.; Nguyen, Brian T.; Clark, Ronald J.; Zhu, Lei

    2011-01-01

    A mechanistic model is formulated to account for the high reactivity of chelating azides (organic azides capable of chelation-assisted metal coordination at the alkylated azido nitrogen position) and copper(II) acetate (Cu(OAc)2) in copper(II)-mediated azide-alkyne cycloaddition (AAC) reactions. Fluorescence and 1H NMR assays are developed for monitoring the reaction progress in two different solvents – methanol and acetonitrile. Solvent kinetic isotopic effect and pre-mixing experiments give credence to the proposed different induction reactions for converting copper(II) to catalytic copper(I) species in methanol (methanol oxidation) and acetonitrile (alkyne oxidative homocoupling), respectively. The kinetic orders of individual components in a chelation-assisted, copper(II)-accelerated AAC reaction are determined in both methanol and acetonitrile. Key conclusions resulting from the kinetic studies include (1) the interaction between copper ion (either in +1 or +2 oxidation state) and a chelating azide occurs in a fast, pre-equilibrium step prior to the formation of the in-cycle copper(I)-acetylide, (2) alkyne deprotonation is involved in several kinetically significant steps, and (3) consistent with prior experimental and computational results by other groups, two copper centers are involved in the catalysis. The X-ray crystal structures of chelating azides with Cu(OAc)2 suggest a mechanistic synergy between alkyne oxidative homocoupling and copper(II)-accelerated AAC reactions, in which both a bimetallic catalytic pathway and a base are involved. The different roles of the two copper centers (a Lewis acid to enhance the electrophilicity of the azido group and a two-electron reducing agent in oxidative metallacycle formation, respectively) in the proposed catalytic cycle suggest that a mixed valency (+2 and +1) dinuclear copper species be a highly efficient catalyst. This proposition is supported by the higher activity of the partially reduced Cu(OAc)2 in

  13. Chelator induced phytoextraction and in situ soil washing of Cu

    Energy Technology Data Exchange (ETDEWEB)

    Kos, Bostjan; Lestan, Domen

    2004-11-01

    In a soil column experiment, we investigated the effect of 5 mmol kg{sup -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{sup -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{sup -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{sup -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.

  14. Portable Solid Phase Extraction of Copper, Cadmium and Lead Using Analig ME-02 Chelating Resin and Their Determination by Atomic Absorption Spectrometry

    Directory of Open Access Journals (Sweden)

    Mohamed Abousa Gaza

    2014-06-01

    Full Text Available The adsorption of metallic elements on the solid phase chelating resins is probably the most effective separation and preconcentration methods. In this work, portable Solid phase extraction (SPE was constructed using a commercially available plastic syringe containing certain amount of the Analiq ME-02 chelating resin. The ability of this portable SPE was evaluated through adsorption-desorption process of copper, lead, and cadmium prior their determination by atomic absorption spectrometry (AAS. Some parameters affecting the adsorption-desorption of these heavy metal ions on the Analiq ME-02, which include effect of pH and concentration of eluent ((HNO3, were investigated in detail. It was found that quantitative adsorptions (> 90% of copper, lead, and cadmium are obtained at all pHs (4- 8 examined, whereas 1 M HNO3 was found to be effective for the desorption of these metals with the recoveries in the range of 93 -114%. Such results indicated that Analig ME-02 has excellent chelating ability (pH-independent for the adsorption of copper, lead, and cadmium, while portable SPE system provides easiness and effectiveness for collection/preconcentation of metallic elements

  15. EVALUATION OF THE CHELATING EFFECT OF METHANOLIC EXTRACT OFCORIANDRUM SATIVUMAND ITS FRACTIONS ON WISTAR RATS POISONED WITH LEAD ACETATE.

    Science.gov (United States)

    Téllez-López, Miguel Ángel; Mora-Tovar, Gabriela; Ceniceros-Méndez, Iromi Marlen; García-Lujan, Concepción; Puente-Valenzuela, Cristo Omar; Vega-Menchaca, María Del Carmen; Serrano-Gallardo, Luis Benjamín; Garza, Rubén García; Morán-Martínez, Javier

    2017-01-01

    The rate of lead poisoning has decreased in recent years due to increased health control in industries that use this metal. However, it is still a public health problem worldwide. The use of various plants with chelating properties has been a topic of research today. In traditional medicine, it is said that Coriandrum sativum has chelating properties, but there is no scientific evidence to support this fact. The purpose of this research is to evaluate the chelating effect of methanol extract of coriander and its fractions on Wistar rats intoxicated with lead. In this research, male Wistar rats were poisoned with 50 mg/kg of lead acetate and treated with 50 mg/kg of methanol extract and its fractions. The extract and its fractions were administered to four treatment groups. Positive and negative controls were established. Hemoglobin, hematocrit and lead concentrations were analyzed; liver was evaluated histologically in control and treatment groups. The methanol extract of coriander presented a LD 50 >1000 mg/dL. The group administered with the methanol extract showed significant difference in the levels of hemoglobin and hematocrit compared to the negative control group. Lead concentration in treatment groups showed a decrease compared to the positive control. Histological evaluation of tissue showed less damage in groups administered with methanolic extract and its fractions compared to the positive control which presented structural alterations. Coriander extracts protect liver and lower lead concentration in rats intoxicated with lead in contrast to the positive control group.

  16. 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.

  17. 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.

  18. Styrene-divinylbenzene copolymers loaded with organophosphorus chelating agents for rare earths separation

    International Nuclear Information System (INIS)

    Barbosa, Celina C.R.; Teixeira, Viviane G.; Coutinho, Fernanda M.B.

    1998-01-01

    Styrene-divinylbenzene copolymers used in extraction chromatography were synthesized in presence of selective chelating agents for rare earths: DEHPA, bis (2-ethylhexyl) phosphoric acid, and EHEHPA, bis (2-ethylhexyl) phosphonic acid. The copolymers were prepared by suspension polymerization technique using the pure chelating agents and its mixture with toluene (TOL) as diluents. The influence of synthesis conditions such as chelating agent/TOL ratios, dilution degree of monomers and amount of DVB on the porous structure of the copolymers were studied. The porous structure was characterized by the apparent density, fixed pore volume, surface area and by optical and scanning electron microscopy. The performance of the copolymers in the separation process of rare earths was evaluated. The total chelating capacity of each copolymer and the chelating kinetics in relation to gadolinium ion were determined. The chelating agent content of the copolymers depend on the amount of chelating agents employed in the synthesis. The highest amount of chelating agent that can be used in the synthesis in order to produce copolymers with high chelating capacity and good mechanical properties was determined. The total chelating capacity varied with the content of the chelating agents in the copolymer and the chelating kinetics was dependent mainly on the pore diameter, because this parameter determines the diffusion rate of the ions though the copolymer structure. (author)

  19. 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.

  20. The magnesium chelation step in chlorophyll biosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, J.D.

    1991-01-01

    The biogenesis of energy transducing membranes requires the coordinate synthesis of prosthetic groups, proteins and lipids. Two of the major prosthetic groups, chlorophyll and heme, share a common biosynthetic pathway that diverges at the point of metal insertion into protoporphyrin IX. Insertion of iron leads to heme, while insertion of magnesium leads to chlorophyll. The Mg-chelatase from intact cucumber chloroplasts has been characterized with regard to substrate specificity, regulation, ATP requirement, and a requirement for intact chloroplasts. Mg-chelatase was isolated from maize, barley and peas and characterized in order to circumvent the intact chloroplast requirement of cucumber Mg-chelatase. Pea Mg-chelatase activity is higher than cucumber Mg-chelatase activity, and lacks the requirement for intact chloroplasts. Studies on isolated pea Mg-chelatase have shown more cofactors are required for the reaction than are seen with ferrochelatase, indicating a greater opportunity for regulatory control of this pathway. Two of the cofactors are proteins, and there appears to be a requirement for a protease-sensitive component which is outside the outer envelope. We are developing a continuous spectrophotometric assay for Mg-chelatase activity, and an assay for free heme which has shown heme efflux from intact chloroplasts. 18 refs. (MHB)

  1. 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.

  2. 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

  3. 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

  4. Antioxidant properties of modified rutin esters by DPPH, reducing power, iron chelation and human low density lipoprotein assays

    DEFF Research Database (Denmark)

    Lue, Bena-Marie; Nielsen, Nina Skall; Jacobsen, Charlotte

    2010-01-01

    rutin compounds exhibited decreased reducing power and metal chelating abilities as compared to rutin. Conversely, investigations on the oxidation of human low density lipoprotein (LDL) revealed that rutin laurate was most effective in inhibiting oxidation by prolonging LDL lag time for an in vitro...... in improved antioxidant abilities in more complex systems, including LDL-oxidation assays. Likely reasons may include improved lipophilic solubility and partitioning properties allowing for better accessibility to the actual site of oxidation. (C) 2010 Elsevier Ltd. All rights reserved....

  5. Synthesis and metal binding properties of salicylate-, catecholate-, and hydroxypyridinonate-functionalized dendrimers.

    Science.gov (United States)

    Cohen, S M; Petoud, S; Raymond, K N

    2001-01-05

    The synthesis, characterization, and metal-binding studies of chelate-functionalized dendrimers is reported. Salicylate, catecholate, and hydroxypyridinonate bidentate chelators have been coupled to the surface of both poly(propyleneimine) (Astramol) and poly(amidoamine) (Starburst, PAMAM) dendrimers up to the fifth generation (64 endgroups). A general method has been developed for the facile and high quality chromatographic purification of poly(propyleneimine) and poly(amidoamine) dendrimer derivatives. One- and two-dimensional (TOCSY) 1H NMR experiments and electrospray ionization mass spectrometry (ESI-MS) have confirmed the exhaustive coupling of these chelators to the primary amine functionalities of the dendrimers. Spectrophotometric titrations were used to investigate the metal binding ability of these macrochelates. Spectral analysis shows that ferric iron binding to these ligands is localized to the chelating endgroups. The ability of these dendritic polymers to bind large numbers of metal ions may lead to applications as metal sequestering agents for waste remediation technologies.

  6. Treatment of some radioactive wastes by using new chelating membranes

    International Nuclear Information System (INIS)

    Hegazy, S.A.; El-Adham, K.; Abdel Geleel, M.; Soliman, S.A.

    2000-01-01

    The preparation of chelating membranes containing nitrile and carboxylic acid as functional groups was investigated. The modification of such membranes by chemical treatments to produce significant changes in their properties was studied. This modification results in a higher rate of exchange and higher capacity. The applicability of such modified membranes in the removal of Co-60 and Cs-137 from their wastes were tested. The dependence of these radioactive nuclides uptake on the time and degree of grafting for H CI-, NH 2 OH-and KOH-treated membranes was investigated. It was found that the adsorption rate and capacity were higher for KOH-treated membrane than those for the NH 2 OH and H CI treated ones. The prepared grafted membranes have a good affinity towards the adsorption or chelation with Co-60 and Cs-137. This result may make such prepared materials acceptable for practicable use in some radioactive waste treatments and recovery

  7. Iron chelators target both proliferating and quiescent cancer cells

    OpenAIRE

    Frykn?s, M?rten; Zhang, Xiaonan; Bremberg, Ulf; Senkowski, Wojciech; Olofsson, Maria H?gg; Brandt, Peter; Persson, Ingmar; D?Arcy, Padraig; Gullbo, Joachim; Nygren, Peter; Schughart, Leoni Kunz; Linder, Stig; Larsson, Rolf

    2016-01-01

    Poorly vascularized areas of solid tumors contain quiescent cell populations that are resistant to cell cycle-active cancer drugs. The compound VLX600 was recently identified to target quiescent tumor cells and to inhibit mitochondrial respiration. We here performed gene expression analysis in order to characterize the cellular response to VLX600. The compound-specific signature of VLX600 revealed a striking similarity to signatures generated by compounds known to chelate iron. Validation exp...

  8. Acute Liver Failure During Deferasirox Chelation: A Toxicity Worth Considering.

    Science.gov (United States)

    Menaker, Nathan; Halligan, Katharine; Shur, Natasha; Paige, John; Hickling, Matthew; Nepo, Anne; Weintraub, Lauren

    2017-04-01

    This case report details a unique case of acute, reversible liver failure in a 12-year-old male with sickle cell anemia on chronic transfusion protocol and deferasirox chelation. There is substantial literature documenting deferasirox-induced renal injury, including Fanconi syndrome, but less documentation of hepatic toxicity and few reports of hepatic failure. The case highlights the importance of close monitoring of ferritin, bilirubin, and transaminases for patients on deferasirox.

  9. Self-assembled polymeric chelate nanoparticles as potential theranostic agents

    Czech Academy of Sciences Publication Activity Database

    Škodová, Michaela; Černoch, Peter; Štěpánek, Petr; Chánová, Eliška; Kučka, Jan; Kálalová, Zuzana; Kaňková, Dana; Hrubý, Martin

    2012-01-01

    Roč. 13, č. 18 (2012), s. 4244-4250 ISSN 1439-4235 R&D Projects: GA ČR GPP207/10/P054; GA ČR GA202/09/2078; GA ČR GAP304/12/0950 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : chelates * nanoparticles * polymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.349, year: 2012

  10. Simplified synthesis of the bifunctional chelating agent 2-(4-aminobenzyl)-1,4,7,10-tetraazacyclododecane-N,N``,N```-tetraacetic acid

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, A.K.; Gestin, J.F.; Benoist, E.; Faivre-Chauvet, A.; Chatal, J.F. [INSERM, 44 Nantes (France)

    1996-05-01

    The attachment of metal ions to antibodies by means of bifunctional chelating agents (BCA) for medical applications requires extremely high stability under physiological conditions, with no significant release of metals. Chelators that bind strongly with radio-metals like {sup 111}In, {sup 67}Ga, {sup 90} Y, and {sup 153} Sm, giving complexes that are highly stable under these conditions are essential for effective radioimmunotherapy, for tumor imaging or immunoscintigraphy. 2-(4-Nitrobenzyl)-1,4,7,10-tetraazacyclodecane-N, N`, N``, N``` -tetraacetic acid (nitrobenzyl-DOTA) is one of the most promising BCA. A convenient synthesis of 4-nitrobenzyl-substituted DOTA and its conversion to bifunctional chelating agents is described here. The process involves the reaction of a bisbromoamide with a p-nitrobenzyl ethylenediamine followed by reduction of the cyclic diamide. The bis-bromoamide resembles a crab with two reactive organo-bromide groups poised and ready to react, hence the term ``crab-like`` cyclization. The overall yield for the six-step synthesis sequence starting form p-nitrobenzyl ethylenediamine is 21.27 %. (authors). 14 refs., 1 fig.

  11. Mercury removal in utility wet scrubber using a chelating agent

    Science.gov (United States)

    Amrhein, Gerald T.

    2001-01-01

    A method for capturing and reducing the mercury content of an industrial flue gas such as that produced in the combustion of a fossil fuel or solid waste adds a chelating agent, such as ethylenediaminetetraacetic acid (EDTA) or other similar compounds like HEDTA, DTPA and/or NTA, to the flue gas being scrubbed in a wet scrubber used in the industrial process. The chelating agent prevents the reduction of oxidized mercury to elemental mercury, thereby increasing the mercury removal efficiency of the wet scrubber. Exemplary tests on inlet and outlet mercury concentration in an industrial flue gas were performed without and with EDTA addition. Without EDTA, mercury removal totaled 42%. With EDTA, mercury removal increased to 71%. The invention may be readily adapted to known wet scrubber systems and it specifically provides for the removal of unwanted mercury both by supplying S.sup.2- ions to convert Hg.sup.2+ ions into mercuric sulfide (HgS) and by supplying a chelating agent to sequester other ions, including but not limited to Fe.sup.2+ ions, which could otherwise induce the unwanted reduction of Hg.sup.2+ to the form, Hg.sup.0.

  12. 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.

  13. Antibacterial and antibiofilm effects of iron chelators against Prevotella intermedia.

    Science.gov (United States)

    Moon, Ji-Hoi; Kim, Cheul; Lee, Hee-Su; Kim, Sung-Woon; Lee, Jin-Yong

    2013-09-01

    Prevotella intermedia, a major periodontopathogen, has been shown to be resistant to many antibiotics. In the present study, we examined the effect of the FDA-approved iron chelators deferoxamine (DFO) and deferasirox (DFRA) against planktonic and biofilm cells of P. intermedia in order to evaluate the possibility of using these iron chelators as alternative control agents against P. intermedia. DFRA showed strong antimicrobial activity (MIC and MBC values of 0.16 mg ml(-1)) against planktonic P. intermedia. At subMICs, DFRA partially inhibited the bacterial growth and considerably prolonged the bacterial doubling time. DFO was unable to completely inhibit the bacterial growth in the concentration range tested and was not bactericidal. Crystal violet binding assay for the assessment of biofilm formation by P. intermedia showed that DFRA significantly decreased the biofilm-forming activity as well as the biofilm formation, while DFO was less effective. DFRA was chosen for further study. In the ATP-bioluminescent assay, which reflects viable cell counts, subMICs of DFRA significantly decreased the bioactivity of biofilms in a concentration-dependent manner. Under the scanning electron microscope, P. intermedia cells in DFRA-treated biofilm were significantly elongated compared to those in untreated biofilm. Further experiments are necessary to show that iron chelators may be used as a therapeutic agent for periodontal disease.

  14. The removal of strontium from the mouse by chelating agents

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-07-01

    The effects of the chelating agents monosodium glutamate, Tiron, tartaric acid, ascorbic acid, 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6), 2,3-dimercaptosuccinic acid (DMSA), succinic acid, malic acid, ethylendiaminetetraacetic acid (EDTA), ethylenglycol-bis-(beta-amino-ethylether)-N,N'tetraacetic acid (EGTA), cyclohexane-diaminetetraacetic acid (CDTA) and diethylentria-minepentaacetic acid (DTPA) on the distribution and excretion of intraperitoneally injected strontium were investigated in male Swiss mice. Strontium nitrate was given at a dose equal to 3.78 mmol/kg and ten minutes after, chelators were administered intraperitoneally at doses approximately equal to one-fourth of their respective LD50 values. DTPA, followed by CDTA, EDTA and tartaric acid, was consistently the most effective in increasing the urinary excretion of strontium. Only ascorbic acid increased significantly the fecal excretion of strontium. CDTA, DTPA and ascorbic acid were also the most effective chelators in reducing the concentration of strontium found in various tissues. CDTA, DTPA and tartaric acid are the most effective agents of those tested in the removal of strontium after a single administration.

  15. 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...

  16. Higher coordination numbers of metals in isolated complexes

    International Nuclear Information System (INIS)

    Wells, A.F.

    1988-01-01

    The material pertaining to island complexes with polydentate ligands where transition and rare earth metals have coordination numbers from 7 to 10 is generalized. The coordination of different ligands in the complexes of these metals depending on the chemical composition and structure of chelating ligand, as well as characteristics of the central atom, is considered

  17. The protection conferred by chelation therapy in post-MI diabetics might be replicated by high-dose zinc supplementation.

    Science.gov (United States)

    McCarty, Mark F; DiNicolantonio, James J

    2015-05-01

    The recent Trial to Assess Chelation Therapy (TACT) study, enrolling subjects who had previously experienced a myocardial infarction, has provided strong evidence that intravenous chelation therapy can markedly reduce risk for mortality and vascular events in diabetics, whereas no discernible benefit was observed in non-diabetics. It has plausibly been suggested that this reflects a role for transition metal ions--iron or copper--in the genesis of advanced glycation end products, key mediators of diabetic complications that can destabilize plaque. Since phlebotomy therapy fails to prevent vascular events in diabetics, we hypothesize that labile copper may be the chief culprit whose removal by chelation mediated the benefit observed in TACT. If so, strategies less time and labor intensive than chelation therapy might provide comparable benefit. A number of recent studies report that the copper-specific orally-active chelator trientine can reduce risk for range of diabetic complications in rodents; a clinical trial with this agent demonstrated some decrease in left ventricular mass in diabetics with ventricular hypertrophy. However, until this agent becomes less expensive, supplementation with high-dose zinc may represent a more feasible alternative. Zinc opposes the absorption and redox activity of copper via induction of the antioxidant protein metallothionein, which binds copper tightly. A great many studies demonstrate that increased expression of metallothionein decreases risk for tissue damage in diabetic rodents, and in some of these studies metallothionein expression was boosted by supplemental zinc. Zinc supplementation also modestly improves glycemic control in type 2 diabetics, and might reduce risk for diabetes by protecting pancreatic beta cells from oxidative stress. A long term study assessing the impact of supplementing diabetics with high-dose zinc, assessing risk for mortality, vascular events, and diabetic complications, may be warranted. Histidine

  18. Development of phosphonic acid chelating fibers by means of electron beam irradiation induced graft polymerization technique

    International Nuclear Information System (INIS)

    Jyo, Akinori; Aoki, Shoji; Yamabe, Kazunori; Shuto, Taketomi

    2001-01-01

    Chloromethylstyrene was graft-polymerized onto polyethylene coated polypropylene fibers (0.9 denier) and its nonwoven cloth (1.5 denier) by means of electron beam irradiation induced graft polymerization technique. The grafted fiber and cloth were reacted with phosphorus trichloride in the presence of anhydrous aluminum trichloride under reflux of phosphorus trichloride, and the followed hydrolysis gave the objective phosphonic acid fibrous chelating exchangers FCSP-c (cloth type) and FCSP-f (fiber type) with phosphorus contents of 3.3 ± 0.2 mmol/g and acid capacities of 5.5 ± 0.2 meq/g. Adsorption rates of Pb(II), Cu(II) and Cd(II) by FCSP-c and FCSP-f were evaluated by batchwise and columnar methods, and compared with those by a chelating resin RCSP having the same functional groups. In batchwise and columnar adsorption of these metal ions, both FCSP-c and FCSP-f exhibited extremely higher adsorption rates than did the resin RCSP. For instance, FCSP-f packed columns exhibited flow rate independent breakthrough capacities of ca. 0.7-0.8 mmol/g for Cu(II) and Cd(II) within the tested range of flow rates from 50 to 1000 h -1 in space velocity, whereas breakthrough capacities of a RCSP resin packed one for Cu(II) decreased markedly with an increase in flow rate. For example, the breakthrough capacity of RCSP column at the flow rate of 500 h -1 was only ca. 0.2 mmol/g. (author)

  19. Isolation and characterization of Fe(III)-chelate reductase gene LeFRO1 in tomato.

    Science.gov (United States)

    Li, Lihua; Cheng, Xudong; Ling, Hong-Qing

    2004-01-01

    Tomato is a model plant for studying molecular mechanisms of iron uptake and metabolism in strategy I plants (dicots and non-graminaceous monocots). Reduction of ferric to ferrous iron on the root surface is an obligatory process for iron acquisition from soil in these plants. LeFRO1 encoding an Fe(III)-chelate reductase protein was isolated from the tomato genome. We show that expression of LeFRO1 in yeast increases Fe(III)-chelate reductase activity. In a transient expression analysis we found that LeFRO1 protein was targeted on the plasma membrane. LeFRO1 transcript was detected in roots, leaves, cotyledons, flowers and young fruits by RT-PCR analysis. Abundance of LeFRO1 mRNA was much lower in young fruits than in other tissues. The transcription intensity of LeFRO1 in roots is dependent on the iron status whereas it is constitutively expressed in leaves. These results indicate that LeFRO1 is required in roots and shoots as well as in reproductive organs for iron homeostasis and that its transcription in roots and shoots is regulated by different control mechanisms. The expression of LeFRO1 was disrupted in the iron-inefficient mutants chloronerva and T3238 fer, indicating that FER and CHLN genes are involved in the regulation of LeFRO1 expression in tomato roots. The differential expression of LeFRO1 and LeIRT1 (an iron-regulated metal transporter gene in tomato) in roots of T3238 fer under iron-deficient and -sufficient conditions suggests that the FER gene may regulate expression of LeFRO1 more directly than that of LeIRT1 in tomato roots.

  20. Interaction of Actinide Species with Microorganisms & Microbial Chelators: Cellular Uptake, Toxicity, & Implications for Bioremediation of Soil & Ground Water.

    Energy Technology Data Exchange (ETDEWEB)

    Hakim Boukhalfa

    2006-03-28

    Microorganisms influence the natural cycle of major elements, including C, N, P, S, and transition metals such as Mn and Fe. Bacterial processes can also influence the behavior of actinides in soil and ground water. While radionuclides have no known biological utility, they have the potential to interact with microorganisms and to interfere with processes involving other elements such as Fe and Mn. These interactions can transform radionuclides and affect their fate and transport. Organic acids, extruded by-products of cell metabolism, can solubilize radionuclides and facilitate their transport. The soluble complexes formed can be taken up by the cells and incorporated into biofilm structures. We have examined the interactions of Pu species with bacterial metabolites, studied Pu uptake by microorganisms and examined the toxicity of Pu and other toxic metals to environmentally relevant bacteria. We have also studied the speciation of Pu(IV) in the presence of natural and synthetic chelators.

  1. The role of chelating agents on the corrosion mechanisms of aluminium in alkaline aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Mercier, D. [Centre d' Etudes de Chimie Metallurgique, CNRS, 15 rue Georges Urbain, 94407 Vitry Cedex (France); Barthes-Labrousse, M.-G. [Centre d' Etudes de Chimie Metallurgique, CNRS, 15 rue Georges Urbain, 94407 Vitry Cedex (France)], E-mail: marie-genevieve.barthes@u-psud.fr

    2009-02-15

    The influence of 1,2-diaminoethane (DAE) on the mechanism of aluminium corrosion in KOH solutions at pH 13 was investigated by combining time-resolved inductively coupled plasma optical emission spectrocopy, open-circuit potential measurements and X-ray photoelectron spectroscopy. In pure KOH solutions, a very slow corrosion rate is initially observed, corresponding to the dissolution of the native oxide layer. Following this incubation stage, the corrosion rate is increasing due to the formation and oxidation of Al hydride, until a steady state is reached. DAE behaves as a strong initial corrosion accelerator, due to synergistic effects with hydroxyl ions and a dissolution mechanism in three successive steps has been proposed: (i) a rapid initial dissolution induced by the formation and detachment from the surface of bidentate (chelate) Al-DAE metal bound surface complexes; (ii) a slower step ascribed to the formation and release of monodentate Al-DAE metal bound surface complexes and (iii) a final step dominated by direct oxidation of surface aluminium hydride by hydroxyl species as in pure KOH.

  2. 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

  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. Enhanced metal extractive behavior using dual mechanism bifunctional polymer: an effective metal chelatogen.

    Science.gov (United States)

    Prabhakaran, D; Subramanian, M S

    2003-11-12

    A new class of chelating polymers using Amberlite XAD-16 (AXAD-16) modified with (N-(3,4-dihydroxy)benzyl)-4-amino,3-hydroxynapthalene-1-sulphonic acid has been developed based on dual mechanism bifunctional polymers, for the extraction of transition and post-transition metal ions. The optimum pH conditions for the quantitative sorption of metal ions were studied. The developed method showed superior extraction qualities with high metal loading capacities of 71, 85, 182, 130 and 46 mg g(-1) for Ni(II), Cd(II), Pb(II), Cu(II) and Co(II), respectively. The rate of metal ion uptake i.e. kinetics studies performed under optimum levels showed a time duration of metal ion saturation. Desorption of metal ions were effective with 15 ml of 2 M HCl/HNO(3) prior to detection using flame atomic absorption spectrophotometer. The chelating polymer was highly ion-selective in nature even in the presence of large concentrations of alkali and alkaline earth metal ions, with a high preconcentrating ability for the metal ions of interest. The developed chelating matrix was tested on its utility with synthetic and real samples like river/sea/tap/well water samples and also with multivitamin/mineral tablets, showed R.S.D. values of <2.5% reflecting on the accuracy and reproducibility of data using the newly developed resin matrix.

  5. Metallophore mapping in complex matrices by metal isotope coded profiling of organic ligands.

    Science.gov (United States)

    Deicke, Michael; Mohr, Jan Frieder; Bellenger, Jean-Philippe; Wichard, Thomas

    2014-12-07

    Metal isotope coded profiling (MICP) introduces a universal discovery platform for metal chelating natural products that act as metallophores, ion buffers or sequestering agents. The detection of cation and oxoanion complexing ligands is facilitated by the identification of unique isotopic signatures created by the application of isotopically pure metals.

  6. Developing Targeted Hybrid Imaging Probes by Chelator Scaffolding.

    Science.gov (United States)

    Summer, Dominik; Grossrubatscher, Leo; Petrik, Milos; Michalcikova, Tereza; Novy, Zbynek; Rangger, Christine; Klingler, Maximilian; Haas, Hubertus; Kaeopookum, Piriya; von Guggenberg, Elisabeth; Haubner, Roland; Decristoforo, Clemens

    2017-06-21

    Positron emission tomography (PET) as well as optical imaging (OI) with peptide receptor targeting probes have proven their value for oncological applications but also show restrictions depending on the clinical field of interest. Therefore, the combination of both methods, particularly in a single molecule, could improve versatility in clinical routine. This proof of principle study aims to show that a chelator, Fusarinine C (FSC), can be utilized as scaffold for novel dimeric dual-modality imaging agents. Two targeting vectors (a minigastrin analogue (MG11) targeting cholecystokinin-2 receptor overexpression (CCK2R) or integrin α V β 3 targeting cyclic pentapeptides (RGD)) and a near-infrared fluorophore (Sulfo-Cyanine7) were conjugated to FSC. The probes were efficiently labeled with gallium-68 and in vitro experiments including determination of logD, stability, protein binding, cell binding, internalization, and biodistribution studies as well as in vivo micro-PET/CT and optical imaging in U-87MG α V β 3 - and A431-CCK2R expressing tumor xenografted mice were carried out. Novel bioconjugates showed high receptor affinity and highly specific targeting properties at both receptors. Ex vivo biodistribution and micro-PET/CT imaging studies revealed specific tumor uptake accompanied by slow blood clearance and retention in nontargeted tissues (spleen, liver, and kidneys) leading to visualization of tumors at early (30 to 120 min p.i.). Excellent contrast in corresponding optical imaging studies was achieved especially at delayed time points (24 to 72 h p.i.). Our findings show the proof of principle of chelator scaffolding for hybrid imaging agents and demonstrate FSC being a suitable bifunctional chelator for this approach. Improvements to fine-tune pharmacokinetics are needed to translate this into a clinical setting.

  7. Advances in iron chelation therapy: transitioning to a new oral formulation

    OpenAIRE

    Shah, Nirmish R.

    2017-01-01

    Iron overload is a concern for patients who require repeated red-blood-cell transfusions due to conditions such as sickle cell disease, thalassemia, or myelodysplastic syndromes. The recommended treatment for removing excess iron in these patients is iron chelation therapy. Currently available iron chelators include deferoxamine, which is administered by injection, and deferasirox and deferiprone, both of which are administered orally. Adherence to iron chelator therapy is an important consid...

  8. Chelate-modified polymers for atmospheric gas chromatography

    Science.gov (United States)

    Christensen, W. W.; Mayer, L. A.; Woeller, F. H. (Inventor)

    1980-01-01

    Chromatographic materials were developed to serve as the stationary phase of columns used in the separation of atmospheric gases. These materials consist of a crosslinked porous polymer matrix, e.g., a divinylbenzene polymer, into which has been embedded an inorganic complexed ion such as N,N'-ethylene-bis-(acetylacetoniminato)-cobalt (2). Organic nitrogenous bases, such as pyridine, may be incorporated into the chelate polymer complexes to increase their chromatographic utility. With such materials, the process of gas chromatography is greatly simplified, especially in terms of time and quantity of material needed for a gas separation.

  9. 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.

  10. 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.

  11. A ferric-chelate reductase for iron uptake from soils.

    Science.gov (United States)

    Robinson, N J; Procter, C M; Connolly, E L; Guerinot, M L

    1999-02-25

    Iron deficiency afflicts more than three billion people worldwide, and plants are the principal source of iron in most diets. Low availability of iron often limits plant growth because iron forms insoluble ferric oxides, leaving only a small, organically complexed fraction in soil solutions. The enzyme ferric-chelate reductase is required for most plants to acquire soluble iron. Here we report the isolation of the FRO2 gene, which is expressed in iron-deficient roots of Arabidopsis. FRO2 belongs to a superfamily of flavocytochromes that transport electrons across membranes. It possesses intramembranous binding sites for haem and cytoplasmic binding sites for nucleotide cofactors that donate and transfer electrons. We show that FRO2 is allelic to the frd1 mutations that impair the activity of ferric-chelate reductase. There is a nonsense mutation within the first exon of FRO2 in frd1-1 and a missense mutation within FRO2 in frd1-3. Introduction of functional FRO2 complements the frd1-1 phenotype in transgenic plants. The isolation of FRO2 has implications for the generation of crops with improved nutritional quality and increased growth in iron-deficient soils.

  12. Functional characterization of the chloroplast ferric chelate oxidoreductase enzyme.

    Science.gov (United States)

    Solti, Adám; Müller, Brigitta; Czech, Viktória; Sárvári, Éva; Fodor, Ferenc

    2014-05-01

    Iron (Fe) has an essential role in the biosynthesis of chlorophylls and redox cofactors, and thus chloroplast iron uptake is a process of special importance. The chloroplast ferric chelate oxidoreductase (cFRO) has a crucial role in this process but it is poorly characterized. To study the localization and mechanism of action of cFRO, sugar beet (Beta vulgaris cv Orbis) chloroplast envelope fractions were isolated by gradient ultracentrifugation, and their purity was tested by western blotting against different marker proteins. The ferric chelate reductase (FCR) activity of envelope fractions was studied in the presence of NAD(P)H (reductants) and FAD coenzymes. Reduction of Fe(III)-ethylenediaminetetraacetic acid was monitored spectrophotometrically by the Fe(II)-bathophenanthroline disulfonate complex formation. FCR activity, that is production of free Fe(II) for Fe uptake, showed biphasic saturation kinetics, and was clearly associated only to chloroplast inner envelope (cIE) vesicles. The reaction rate was > 2.5 times higher with NADPH than with NADH, which indicates the natural coenzyme preference of cFRO activity and its dependence on photosynthesis. FCR activity of cIE vesicles isolated from Fe-deficient plants also showed clear biphasic kinetics, where the KM of the low affinity component was elevated, and thus this component was down-regulated. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  13. Deferasirox, an oral chelator in the treatment of iron overload

    Directory of Open Access Journals (Sweden)

    I. Portioli

    2013-05-01

    Full Text Available BACKGROUND Deferasirox is a once-daily oral iron chelator developed for treating iron overload complicating long-term transfusion therapy in patients with diseases such as beta-thalassemia and myelodysplastic syndromes. Iron overload can damage the liver, pancreas and the heart. Deferoxamine, the only other drug approved for iron chelation, can prevent these effects but requires parenteral administration. Deferasirox has been approved after a one-year, open-label trial in patients ≥ 2 years old with beta-thalassemia and transfusional emosiderosis randomized to once-daily oral 5, 10, 20, 30 mg/kg/day in comparison of subcutaneous deferoxamine 20-60 mg/mg/kg/day x 5/week. CONCLUSIONS Deferasirox 20-30 mg/kg/day produced reductions in liver iron concentration (LIC similar to those with deferoxamine. Adverse effect of deferasirox (increases of serum creatinine and aminotransferases, including the gastrointestinal ones, are similar but more frequent than those occurring with deferoxamine. Information is lacking on the effects of deferasirox on cardiac iron and cardiac dysfunction which is the most serious complication of transfusional iron overload.

  14. Antiradical, Chelating and Antioxidant Activities of Hydroxamic Acids and Hydroxyureas

    Directory of Open Access Journals (Sweden)

    Branka Zorc

    2011-07-01

    Full Text Available Reactive oxygen species, along with reactive nitrogen species, may play an important role in the pathogenesis and progress of many diseases, including cancer, diabetes and sickle cell disease. It has been postulated that hydroxyurea, one of the main treatments in sickle cell disease, achieves its activity partly also through its antioxidant properties. A series of hydroxyurea derivatives of L- and D-amino acid amides and cycloalkyl-N-aryl-hydroxamic acids was synthesized and investigated for their radical scavenging activity, chelating properties and antioxidant activity. All the compounds showed exceptional antiradical activities. For example, free radical scavenging activities of investigated hydroxyureas were higher than the activity of standard antioxidant, butylated hydroxyanisole (BHA. Moreover, most of the investigated hydroxamic acids were stronger Fe2+ ion chelators than quercetin. In addition, the investigated compounds, especially hydroxamic acids, were proven to be excellent antioxidants. They were as effective as BHA in inhibiting b-carotene-linoleic acid coupled oxidation. It is reasonable to assume that the antioxidant activity of the investigated compounds could contribute to their previously proven biological properties as cytostatic and antiviral agents.

  15. Chelating polymeric beads as potential therapeutics for Wilson's disease.

    Science.gov (United States)

    Mattová, Jana; Poučková, Pavla; Kučka, Jan; Skodová, Michaela; Vetrík, Miroslav; Stěpánek, Petr; Urbánek, Petr; Petřík, Miloš; Nový, Zbyněk; Hrubý, Martin

    2014-10-01

    Wilson's disease is a genetic disorder caused by a malfunction of ATPase 7B that leads to high accumulation of copper in the organism and consequent toxic effects. We propose a gentle therapy to eliminate the excessive copper content with oral administration of insoluble non-resorbable polymer sorbents containing selective chelating groups for copper(II). Polymeric beads with the chelating agents triethylenetetramine, N,N-di(2-pyridylmethyl)amine, and 8-hydroxyquinoline (8HQB) were investigated. In a preliminary copper uptake experiment, we found that 8HQB significantly reduced copper uptake (using copper-64 as a radiotracer) after oral administration in Wistar rats. Furthermore, we measured organ radioactivity in rats to demonstrate that 8HQB radiolabelled with iodine-125 is not absorbed from the gastrointestinal tract after oral administration. Non-resorbability and the blockade of copper uptake were also confirmed with small animal imaging (PET/CT) in mice. In a long-term experiment with Wistar rats fed a diet containing the polymers, we have found that there were no signs of polymer toxicity and the addition of polymers to the diet led to a significant reduction in the copper contents in the kidneys, brains, and livers of the rats. We have shown that polymers containing specific ligands could potentially be novel therapeutics for Wilson's disease. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. [MR imaging of lung ventilation with aerosolized gadolinium-chelates].

    Science.gov (United States)

    Haage, P; Karaagac, S; Spüntrup, E; Adam, G; Günther, R W

    2003-02-01

    To evaluate the feasibility of magnetic resonance assessment of human lung ventilation with aerosolized Gd-chelates in healthy volunteers. Five healthy adults (mean age 37 years) were studied with a 1.5 T unit. The volunteers were instructed to inhale the aerosol through an airtight facial mask for 10 minutes. The aerosol was generated with a jet-type small particle nebulizer with attached heater. Ventilation imaging was performed using a respiration-gated dynamic T1-weighted turbo spin echo sequence (T(R) = 199 ms, T(E) = 8.5 ms, 12 signal averages, slice thickness 10 mm). Pulmonary signal intensity changes were calculated before and after nebulization. The investigation was successfully carried out in all volunteers. An acute or delayed allergic reaction to the aerosolized contrast medium was not observed. In 4 of 5 experiments (80 %), a homogeneous signal intensity increase was readily visualized with an average signal increase of 35 % after 10 minutes; in one experiment, the aerosol distribution was slightly heterogeneous. The results of the presented phase I clinical study demonstrate the feasibility of human ventilation imaging with aerosolized Gd-chelates for the first time. More trials with a larger number of healthy subjects and patients are needed before the clinical introduction of Gd-based ventilation MR imaging of the lungs.

  17. 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

  18. The application of chelating resin to the elimination of interferences in the analysis of trace hazardous elements

    International Nuclear Information System (INIS)

    Yamazaki, Masao; Goto, Michiko; Nakagawa, Seiko; Hukuchi, Ryouichi; Shirako, Sadaharu

    2005-01-01

    In general, digestion with nitric and sulfuric acids are applied in the analysis of trace elements in solid materials like industrial products and soils. This causes the digested solution to contain high concentrations of sulfate ion. In addition, silicate, chloride and other interferences, which are contained in the material itself, can also be included. These interfering matrices are separated generally through solvent extraction. In stead of the solvent extraction method, we applied the solid phase extraction method using chelating resin, which has a functional group of iminodiacetic acid, for the analysis of trace hazardous metals such as Cd and Pb in industrial products, soils, and other materials containing high concentrations of matrix components. In the presence of high concentrations of interfering ions, over 80% of Cd and Pb and Pb were extracted, with one exception that the recovery of Cd from seawater decreased to 60-30% in the presence of 19g/L of chloride ion. On the other hand, Cr, As and Se were extracted at a low recovery rate with this type of chelating resin. (author)

  19. Effect of chelating agent acetylacetone on corrosion protection properties of silane-zirconium sol–gel coatings

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Mei, E-mail: yumei@buaa.edu.cn; Liang, Min; Liu, Jianhua; Li, Songmei; Xue, Bing; Zhao, Hao

    2016-02-15

    Graphical abstract: - Highlights: • AcAc was employed as a chelating agent in order to form stable sols. • The sol particle size depends on the concentration of AcAc. • AFM results indicate that AcAc content affects the morphology of the coatings. • Coating AcAc3 shows the optimal corrosion protection. - Abstract: The hybrid sol–gel coatings on AA2024-T3 were prepared with a silane coupling agent 3-glycidoxypropyltrimethoxysilane (GPTMS) and a metal alkoxide tetra-n-propoxyzirconium (TPOZ) as precursors. The effect of acetylacetone (AcAc) as a chelating agent on the corrosion protection properties of sol–gel coatings were evaluated and the optimal AcAc/TPOZ molar ratio was obtained. The sol–gel coatings were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The corrosion protection properties of the coatings were evaluated by means of potentiodynamic polarization study (PDS) and electrochemical impedance spectroscopy (EIS). It is demonstrated that AcAc avoids fast hydrolysis of TPOZ and benefits to form stable sols. The coating with AcAc/TPOZ molar ratio of 3 shows the best corrosion protection performance in 0.05 M NaCl solution.

  20. 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.

  1. A rapid assay for evaluation of iron-chelating agents in rats

    International Nuclear Information System (INIS)

    Pippard, M.J.; Johnson, D.K.; Finch, C.A.

    1981-01-01

    The animal assay of potential new iron-chelating agents is at present dependent on cumbersome and imprecise iron balance studies in hypertransfused rodents. We report the development of a radioisotope assay in intact rats based on the transient labeling by ferritin 59Fe of the main source of chelatable iron within hepatocytes. The isotope was maximally available to chelators during the first 6 hr after its injection, nearly all the excretion being in the bile. The bile 59Fe/total iron ratio was independent of both the chelator and its dose. However, in iron-loaded rats, the ratio was reduced, and the isotope excretion was a less sensitive measure of intrahepatic chelation. In the proposed assay, test chelators were given to normal rats 2 hr after an intravenous injection of 59Fe-ferritin. Four hours later, the radioiron in the liver and in the gut gave a sensitive measure of the mobilization of hepatic iron to the bile. In addition, chemical iron determinations identified a small alternative source of urinary chelate with agents known to promote urine excretion in man. The assay gave a rapid and precise screen for chelators given by parenteral and oral routes

  2. Antioxidant, Iron-chelating and Anti-glucosidase Activities of Typha ...

    African Journals Online (AJOL)

    Antioxidant, Iron-chelating and Anti-glucosidase Activities of Typha domingensis Pers (Typhaceae). T Chai, M Mohan, H Ong, F Wong. Abstract. Purpose: To evaluate the phytochemical profile as well as in vitro antioxidant, iron-chelating, and antiglucosidase activities of Typha domingensis Pers. (Typhaceae) Methods: Total ...

  3. The mechanism of activation of amidobenzylidene ruthenium chelates - latent catalysts of olefin metathesis.

    Science.gov (United States)

    Rogalski, Szymon; Żak, Patrycja; Tadeuszyk, Natalia; Pyta, Krystian; Przybylski, Piotr; Pietraszuk, Cezary

    2017-01-24

    Amidobenzylidene ruthenium chelates - latent catalysts of olefin metathesis can be easily activated by the addition of Brønsted or Lewis acids. Their activation in the presence of hydrogen chloride involves the formation of catalytically active trans-dichloro carbamatobenzylidene ruthenium chelates.

  4. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Crosby, W.H.; Green, R.

    1982-01-26

    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.

  6. Brazilian Thalassemia Association protocol for iron chelation therapy in patients under regular transfusion

    Directory of Open Access Journals (Sweden)

    Monica Pinheiro de Almeida Verissimo

    2013-01-01

    Full Text Available In the absence of an iron chelating agent, patients with beta-thalassemia on regular transfusions present complications of transfusion-related iron overload. Without iron chelation therapy, heart disease is the major cause of death; however, hepatic and endocrine complications also occur. Currently there are three iron chelating agents available for continuous use in patients with thalassemia on regular transfusions (desferrioxamine, deferiprone, and deferasirox providing good results in reducing cardiac, hepatic and endocrine toxicity. These practice guidelines, prepared by the Scientific Committee of Associação Brasileira de Thalassemia (ABRASTA, presents a review of the literature regarding iron overload assessment (by imaging and laboratory exams and the role of T2* magnetic resonance imaging (MRI to control iron overload and iron chelation therapy, with evidence-based recommendations for each clinical situation. Based on this review, the authors propose an iron chelation protocol for patients with thalassemia under regular transfusions.

  7. Mesoporous organosilica nanotubes containing a chelating ligand in their walls

    Directory of Open Access Journals (Sweden)

    Xiao Liu

    2014-11-01

    Full Text Available We report the synthesis of organosilica nanotubes containing 2,2′-bipyridine chelating ligands within their walls, employing a single-micelle-templating method. These nanotubes have an average pore diameter of 7.8 nm and lengths of several hundred nanometers. UV-vis absorption spectra and scanning transmission electron microscopy observations of immobilized nanotubes with an iridium complex on the bipyridine ligands showed that the 2,2′-bipyridine groups were homogeneously distributed in the benzene-silica walls. The iridium complex, thus, immobilized on the nanotubes exhibited efficient catalytic activity for water oxidation using Ce4+, due to the ready access of reactants to the active sites in the nanotubes.

  8. Mesoporous organosilica nanotubes containing a chelating ligand in their walls

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiao; Goto, Yasutomo; Maegawa, Yoshifumi; Inagaki, Shinji, E-mail: inagaki@mosk.tytlabs.co.jp [Toyota Central R and D Laboratories, Inc., Nagakute, Aichi 480-1192 (Japan); Japan Science and Technology Agency (JST)/ACT-C, Nagakute, Aichi, 480-1192 (Japan); Ohsuna, Tetsu [Toyota Central R and D Laboratories, Inc., Nagakute, Aichi 480-1192 (Japan)

    2014-11-01

    We report the synthesis of organosilica nanotubes containing 2,2′-bipyridine chelating ligands within their walls, employing a single-micelle-templating method. These nanotubes have an average pore diameter of 7.8 nm and lengths of several hundred nanometers. UV-vis absorption spectra and scanning transmission electron microscopy observations of immobilized nanotubes with an iridium complex on the bipyridine ligands showed that the 2,2′-bipyridine groups were homogeneously distributed in the benzene-silica walls. The iridium complex, thus, immobilized on the nanotubes exhibited efficient catalytic activity for water oxidation using Ce{sup 4+}, due to the ready access of reactants to the active sites in the nanotubes.

  9. Kinetic study of ion exchange in phosphoric acid chelating resin

    International Nuclear Information System (INIS)

    Brikci-Nigassa, Mounir; Hamouche, Hafida

    1995-11-01

    Uranium may be recovered as a by product of wet phosphoric acid using a method based on specific ion exchange resins. These resins called chelates contain amino-phosphonic functional groups. The resin studied in this work is a purolite S-940; uranium may be loaded on this resin from 30% P2O5 phosphoric acid in its reduced state. The influence of different parameters on the successive steps of the process have been studied in batch experiments: uranium reduction, loading and oxydation. Uranium may be eluted with ammonium carbonate and the resin regeneration may be done with hydrochloric acid.Ferric ions reduce the effective resin capacity considerably and inert fixation conditions are proposed to enhance uranium loading

  10. Chelating, antioxidant and hypoglycaemic potential of Muscari comosum (L.) Mill. bulb extracts.

    Science.gov (United States)

    Loizzo, Monica R; Tundis, Rosa; Menichini, Federica; Pugliese, Alessandro; Bonesi, Marco; Solimene, Umberto; Menichini, Francesco

    2010-12-01

    The metal chelating activity, antioxidant properties and the effect on carbohydrate-hydrolysing enzyme inhibition of Muscari comosum extracts have been investigated. M. comosum bulbs contain a total amount of the phenols with a value of 56.6 mg chlorogenic acid equivalent per gram of extract and a flavonoid content of 23.4 mg quercetin equivalent per gram of extract. In order to evaluate the non-polar constituents, n-hexane extract was obtained. Gas chromatography-mass spectrometry analysis revealed the presence of fatty acids and ethyl esters as major constituents, with different aldehydes and alkanes as minor components. Ethanolic extract had the highest ferric-reducing ability power (66.7 μM Fe(II)/g) and DPPH scavenging activity with a concentration giving 50% inhibition (IC₅₀) value of 40.9 μg/ml. Moreover, this extract exhibited a good hypoglycaemic activity with IC₅₀ values of 81.3 and 112.8 μg/ml for α-amylase and α-glucosidase, respectively. In conclusion, M. comosum bulbs show promising antioxidant and hypoglycaemic activity via the inhibition of carbohydrate digestive enzymes. These activities may be of interest from a functional point of view and for the revalorization of this ancient non-cultivated vegetable of Mediterranean traditional gastronomy.

  11. Highly stable acyclic bifunctional chelator for {sup 64}Cu PET imaging

    Energy Technology Data Exchange (ETDEWEB)

    Abada, S.; Lecointre, A.; Christine, C.; Charbonniere, L. [CNRS/UDS, EPCM, Strasbourg (France). Lab. d' Ingenierie Appliquee a l' Analyse; Dechamps-Olivier, I. [Univ. de Reims Champagne Ardenne, Reims (France). Group Chimie de Coordination; Platas-Iglesias, C. [Univ. da Coruna (Spain). Dept. de Quimica Fundamental; Elhabiri, M. [CNRS/UDS, EPCM, Strasbourg (France). Lab. de Physico-Chimie Bioinorganique

    2011-07-01

    Ligand L{sup 1}, based on a pyridine scaffold, functionalized by two bis(methane phosphonate)aminomethyl groups, was shown to display a very high affinity towards Cu(II) (log K{sub CuL}=22.7) and selectivity over Ni(II), Co(II), Zn(II) and Ga(III) ({delta} log K{sub ML}>4) as shown by the values of the stability constants obtained from potentiometric measurements. Insights into the coordination mode of the ligand around Cu(II) cation were obtained by UV-Vis absorption and EPR spectroscopies as well as density functional theory (DFT) calculations (B3LYP model) performed in aqueous solution. The results point to a pentacoordination pattern of the metal ion in the fully deprotonated [CuL{sup 1}]{sup 6-} species. Considering the beneficial thermodynamic parameters of this ligand, kinetic experiments were run to follow the formation of the copper(II) complexes, indicating a very rapid formation of the complex, appropriate for {sup 64}Cu complexation. As L{sup 1} represents a particularly interesting target within the frame of {sup 64}Cu PET imaging, a synthetic protocol was developed to introduce a labeling function on the pyridyl moiety of L{sup 1}, thereby affording L{sup 2}, a potential bifunctional chelator (BFC) for PET imaging.

  12. Copper chelator induced efficient episodic memory recovery in a non-transgenic Alzheimer's mouse model.

    Science.gov (United States)

    Ceccom, Johnatan; Coslédan, Frédéric; Halley, Hélène; Francès, Bernard; Lassalle, Jean Michel; Meunier, Bernard

    2012-01-01

    Alzheimer's disease (AD) is a neurodegenerative syndrom involving many different biological parameters, including the accumulation of copper metal ions in Aβ amyloid peptides due to a perturbation of copper circulation and homeostasis within the brain. Copper-containing amyloids activated by endogenous reductants are able to generate an oxidative stress that is involved in the toxicity of abnormal amyloids and contribute to the progressive loss of neurons in AD. Since only few drugs are currently available for the treatment of AD, we decided to design small molecules able to interact with copper and we evaluated these drug-candidates with non-transgenic mice, since AD is mainly an aging disease, not related to genetic disorders. We created a memory deficit mouse model by a single icv injection of Aβ(1-42) peptide, in order to mimic the early stage of the disease and the key role of amyloid oligomers in AD. No memory deficit was observed in the control mice with the antisense Aβ(42-1) peptide. Here we report the capacity of a new copper-specific chelating agent, a bis-8-aminoquinoline PA1637, to fully reverse the deficit of episodic memory after three weeks of treatment by oral route on non-transgenic amyloid-impaired mice. Clioquinol and memantine have been used as comparators to validate this fast and efficient mouse model.

  13. Copper chelator induced efficient episodic memory recovery in a non-transgenic Alzheimer's mouse model.

    Directory of Open Access Journals (Sweden)

    Johnatan Ceccom

    Full Text Available Alzheimer's disease (AD is a neurodegenerative syndrom involving many different biological parameters, including the accumulation of copper metal ions in Aβ amyloid peptides due to a perturbation of copper circulation and homeostasis within the brain. Copper-containing amyloids activated by endogenous reductants are able to generate an oxidative stress that is involved in the toxicity of abnormal amyloids and contribute to the progressive loss of neurons in AD. Since only few drugs are currently available for the treatment of AD, we decided to design small molecules able to interact with copper and we evaluated these drug-candidates with non-transgenic mice, since AD is mainly an aging disease, not related to genetic disorders. We created a memory deficit mouse model by a single icv injection of Aβ(1-42 peptide, in order to mimic the early stage of the disease and the key role of amyloid oligomers in AD. No memory deficit was observed in the control mice with the antisense Aβ(42-1 peptide. Here we report the capacity of a new copper-specific chelating agent, a bis-8-aminoquinoline PA1637, to fully reverse the deficit of episodic memory after three weeks of treatment by oral route on non-transgenic amyloid-impaired mice. Clioquinol and memantine have been used as comparators to validate this fast and efficient mouse model.

  14. Analysis of the brain tissues from a patient with Alzheimer's disease and effects of chelating treatment

    International Nuclear Information System (INIS)

    Ektessabi, A.M.; Fujisawa, S.; Takada, K.; Yoshida, K.; Murayama, H.; Shin, R.W.

    1999-01-01

    Alzheimer's, Parkinson's disease and ALS are among major neurodegenerative diseases. The cause of neurodegeneration is unknown, but there are indications that excessive accumulation of essential elements, and sometimes, incorporation of toxic foreign elements in neurons aggravate neurodegeneration. During the past decade, many researchers investigated the causative factors in degenerative diseases to specify genetic or environmental factor. PIXE analysis has been used for these studies because of the sample preparation is easy and detection limit is very low. However, the concentration of matrix elements and foreign elements are extremely low and difficult to detect and to quantify. In this study, specimens from patients with Alzheimer's disease with no chemical treatment, and those with chelating were analyzed. In all analyzed specimens, Na, Al, Si, P, S, Cl, Ca, Ti, Vi, Cr, Fe and Cu were detected. Each specimen in this study consisted of cerebral cortex and substantia alba. From these experiments we can observe a clear tendency that the accumulation of the metal elements use different depending on the constituent tissues, and the method of sample preparation has a dominant role in the measurement results. (author)

  15. Clinically approved iron chelators influence zebrafish mortality, hatching morphology and cardiac function.

    Directory of Open Access Journals (Sweden)

    Jasmine L Hamilton

    Full Text Available Iron chelation therapy using iron (III specific chelators such as desferrioxamine (DFO, Desferal, deferasirox (Exjade or ICL-670, and deferiprone (Ferriprox or L1 are the current standard of care for the treatment of iron overload. Although each chelator is capable of promoting some degree of iron excretion, these chelators are also associated with a wide range of well documented toxicities. However, there is currently very limited data available on their effects in developing embryos. In this study, we took advantage of the rapid development and transparency of the zebrafish embryo, Danio rerio to assess and compare the toxicity of iron chelators. All three iron chelators described above were delivered to zebrafish embryos by direct soaking and their effects on mortality, hatching and developmental morphology were monitored for 96 hpf. To determine whether toxicity was specific to embryos, we examined the effects of chelator exposure via intra peritoneal injection on the cardiac function and gene expression in adult zebrafish. Chelators varied significantly in their effects on embryo mortality, hatching and morphology. While none of the embryos or adults exposed to DFO were negatively affected, ICL -treated embryos and adults differed significantly from controls, and L1 exerted toxic effects in embryos alone. ICL-670 significantly increased the mortality of embryos treated with doses of 0.25 mM or higher and also affected embryo morphology, causing curvature of larvae treated with concentrations above 0.5 mM. ICL-670 exposure (10 µL of 0.1 mM injection also significantly increased the heart rate and cardiac output of adult zebrafish. While L1 exposure did not cause toxicity in adults, it did cause morphological defects in embryos at 0.5 mM. This study provides first evidence on iron chelator toxicity in early development and will help to guide our approach on better understanding the mechanism of iron chelator toxicity.

  16. Beryllium Chelation by Dicarboxylic Acids in Aqueous Solution.

    Science.gov (United States)

    Schmidt, Michael; Bauer, Andreas; Schmidbaur, Hubert

    1997-05-07

    Maleic and phthalic acids are found to react with Be(OH)(2), generated in situ from BeSO(4)(aq) and Ba(OH)(2)(aq), in aqueous solution at pH 3.0 or 4.4, respectively (25 degrees C), to give solutions containing the complexes (H(2)O)(2)Be[(OOCCH)(2)] (1) and (H(2)O)(2)Be[(OOC)(2)C(6)H(4)] (3). The products can be isolated in high yield and identified by microanalytical data. With 2 equiv of the dicarboxylic acids and the pH adjusted to 5.5 and 5.9, respectively, by addition of ammonia, the bis-chelate complexes [(NH(4))(+)](2){[Be[(OOCCH)(2)](2)}(2)(-) (2) and [(NH(4))(+)](2){Be[(OOC)(2)C(6)H(4)](2)}(2)(-) (4) are obtained, which can also be isolated. The compounds show distinct (9)Be, (1)H, and (13)C resonances in their NMR spectra in aqueous solutions. Layering of an aqueous solution of compound 4 with acetone at ambient temperature leads to the precipitation of single crystals suitable for an X-ray structure determination. This salt (5) was found to contain the bis-chelated dianion {Be[(OOC)(2)C(6)H(4)](2)}(2)(-) with the beryllium atom in the spiro center of two seven-membered rings and an overall geometry approaching closely C(2) symmetry. These anions are associated with two crystallographically independent but structurally similar counterions [MeC(O)CH(2)CMe(2)NH(3)](+), which are the product of a condensation reaction of the ammonium cation with the acetone solvent. In the crystal the ammonium hydrogen atoms of the cations form N-H.O hydrogen bonds with the oxo functions of the dianion.

  17. Effects of Zinc Chelators on Aflatoxin Production in Aspergillus parasiticus.

    Science.gov (United States)

    Wee, Josephine; Day, Devin M; Linz, John E

    2016-06-02

    Zinc concentrations strongly influence aflatoxin accumulation in laboratory media and in food and feed crops. The presence of zinc stimulates aflatoxin production, and the absence of zinc impedes toxin production. Initial studies that suggested a link between zinc and aflatoxin biosynthesis were presented in the 1970s. In the present study, we utilized two zinc chelators, N,N,N',N'-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and 2,3-dimercapto-1-propanesulfonic acid (DMPS) to explore the effect of zinc limitation on aflatoxin synthesis in Aspergillus parasiticus. TPEN but not DMPS decreased aflatoxin biosynthesis up to six-fold depending on whether A. parasiticus was grown on rich or minimal medium. Although we observed significant inhibition of aflatoxin production by TPEN, no detectable changes were observed in expression levels of the aflatoxin pathway gene ver-1 and the zinc binuclear cluster transcription factor, AflR. Treatment of growing A. parasiticus solid culture with a fluorescent zinc probe demonstrated an increase in intracellular zinc levels assessed by increases in fluorescent intensity of cultures treated with TPEN compared to controls. These data suggest that TPEN binds to cytoplasmic zinc therefore limiting fungal access to zinc. To investigate the efficacy of TPEN on food and feed crops, we found that TPEN effectively decreases aflatoxin accumulation on peanut medium but not in a sunflower seeds-derived medium. From an application perspective, these data provide the basis for biological differences that exist in the efficacy of different zinc chelators in various food and feed crops frequently contaminated by aflatoxin.

  18. 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

  19. Effect of Surface Modification by Chelating Agents on Fischer- Tropsch Performance of Co/SiO{sub 2} Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bambal, Ashish S.; Kugler, Edwin L.; Gardner, Todd H.; Dadyburjor, Dady B.

    2013-11-14

    The silica support of a Co-based catalyst for Fischer-Tropsch (FT) synthesis was modified by the chelating agents (CAs) nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA). After the modification, characterization of the fresh and spent catalysts show reduced crystallite sizes, a better-dispersed Co₃O₄ phase on the calcined samples, and increased metal dispersions for the reduced samples. The CA-modified catalysts display higher CO conversions, product yields, reaction rates and rate constants. The improved FT performance of CA-modified catalysts is attributed to the formation of stable complexes with Co. The superior performance of the EDTA-modified catalyst in comparison to the NTA-modified catalyst is due to the higher affinity of the former for complex formation with Co ions.

  20. Chitosan-functionalized gold nanoparticles for colorimetric detection of mercury ions based on chelation-induced aggregation

    International Nuclear Information System (INIS)

    Chen, Zhengbo; Zhang, Chenmeng; Tan, Yuan; Zhou, Tianhui; Ma, He; Wan, Chongqing; Lin, Yuqing; Li, Kai

    2015-01-01

    We are presenting a colorimetric assay for mercury (II) ions. It is based on citosan-functionalized gold nanoparticles (AuNPs) that act as a signaling probe. Hg (II) induces the aggregation of the chitosan-AuNPs through a chelation reaction that occurs between chitosan and Hg (II). This results in a strong decrease of the absorbance of the modified AuNPs and a color change from red to blue. This sensing system displays excellent selectivity over other metal ions and a detection limit as low as 1.35 μM which is lower than the allowed level of Hg (II) in drinking water (30 μM) as defined by World Health Organization. The method is inexpensive, facile, sensitive, and does not require the addition of other reagents in order to improving sensitivity. (author)

  1. Competitive binding of Pu and Am with bone mineral and novel chelating agents

    International Nuclear Information System (INIS)

    Guilmette, R.A.; Hakimi, R.; Durbin, P.W.; Xu, J.; Raymond, K.N.

    2003-01-01

    Effective direct removal of actinides such as Pu and Am from bone in vivo has not been accomplished to date, even with the strong chelating agents CaNa 3 DTPA or ZnNa 3 DTPA. This study, using an established in vitro system, compared removal of Pu and Am bound to bone mineral by ZnNa 3 DTPA and 10 chelating agents designed specifically to sequester actinides, including Pu and Am. Ligands tested were tetra, hexa, and octadentate, with linear or branched backbones containing sulfocatechol [CAM(S)], hydroxycatechol [CAM(C)], hydroxipyridinone (1,2-HOPO, Me-3,2-HOPO), or hydroxamate functional groups. The wide range of Pu and Am removal exhibited by the test ligands generally agreed with their metal coordination and chemical properties. The most effective agents for Pu (100 μM concentration, 24-48 h contact) are all octadentate as follows: 3,4.3-LICAM(S) (54% unbound); 3,4.3-LICAM(C) (6.2%); 3,4.3-LI(1.2-HOPO) (3.8%); H(2.2)-(Me-3,2-HOPO) (2.2%) and DFO-(1,2-HOPO) (1.8%). The other ligands removed less than 1% of the bound Pu; and ZnNa 3 DTPA removed only 0.086%. The most effective ligands for Am removal (100 μM, 24-48 h contact) are as follows: octadentate H(2.2)-(Me-3,2-HOPO) (21% unbound); 3,4.3-LI(1,2-HOPO) (14.5%) and 3,4.3-LICAM(C) (5.9%); hexadentate TREN-(Me-3,2-HOPO) and TREN-(1,2-HOPO) (9.6%); and tetradentate 5-LIO(Me-3,2-HOPO) (5.2%). Am removal by ZnNa 3 DTPA was about 1.4%. Among the ligands presently considered for possible human use, only 3,4.3-LI(1,2-HOPO) removed potentially useful amounts of both Pu and Am from bone mineral. (author)

  2. Functionalization of Krebs-type polyoxometalates with N,O-chelating ligands: a systematic study.

    Science.gov (United States)

    Artetxe, Beñat; Reinoso, Santiago; San Felices, Leire; Vitoria, Pablo; Pache, Aroa; Martín-Caballero, Jagoba; Gutiérrez-Zorrilla, Juan M

    2015-01-05

    The first organic derivatives of 3d-metal-disubstituted Krebs-type polyoxometalates have been synthesized under mild bench conditions via straightforward replacement of labile aqua ligands with N,O-chelating planar anions on either preformed or in situ-generated precursors. Nine hybrid clusters containing carboxylate derivatives of five- or six-membered aromatic N-heterocycles as antenna ligands have been obtained as pure crystalline phases and characterized by elemental and thermal analyses, infrared spectroscopy, and single-crystal X-ray diffraction. They all show the general formula [{M(II)L(H2O)}2(WO2)2(B-β-XW9O33)2](n-) and can be classified as follows: 1-SbM, where L = 1H-imidazole-4-carboxylate (imc), X = Sb(III), n = 12, and M(II) = Mn, Co, Ni, Zn; 1-TeM, where L = imc, X = Te(IV), n = 10, and M(II) = Mn, Co; 2-SbNi, where L = 1H-pyrazole-3-carboxylate (pzc), X = Sb(III), n = 12, and M(II) = Ni; and 3-SbM, where L = pyrazine-2-carboxylate (pyzc), X =Sb(III), n = 12, and M(II) = Co, Zn. The 3d-metal-disubstituted tungstotellurate(IV) skeleton of compounds 1-TeM is unprecedented in polyoxometalate chemistry. The stability of these hybrid Krebs-type species in aqueous solution has been confirmed by (1)H NMR spectroscopy performed on the diamagnetic 1-SbZn and 3-SbZn derivatives. Our systematic study of the reactivity of disubtituted Krebs-type polyoxotungstates toward diazole-, pyridine-, and diazinecarboxylates demonstrates that organic derivatization is strongly dependent on the nature of the ligand, as follows: imc displays a "universal ligand" character, as functionalization takes place regardless of the external 3d metal and heteroatom; pzc and pyzc show selectivity toward specific 3d metals; pyridazine-3-carboxylate and pyrimidine-4-carboxylate promote partial decomposition of specific precursors, leading to [M(II)L2(H2O)2] complexes; and picolinate is inert under all conditions tested.

  3. Evolution of residual-Zn available concentrations of Zn-EDTA chelate in two different soils.

    Science.gov (United States)

    Almendros, P.; Gonzalez, D.; Alvarez, J. M.

    2012-04-01

    Zinc chelates, such as Zn-EDTA have been widely used to correct deficiencies in this micronutrient in different crops. Several authors have suggested applying complexed forms of Zn to soils in order to offer an effective source of Zn to plants. When inorganic Zn sources are added to soils, the availability of Zn to plants tends to decrease with time. This is due to the aging of the metal or the transformation of the Zn that is normally available to plants into various less available forms. Soil properties are believed to influence the fixation and/or precipitation of added Zn. The objective of this study was to determine the changes over time in the concentrations of available residual-Zn in two different soils to which the Zn-EDTA chelate was applied. An experiment was conducted under controlled laboratory conditions in two different soils: an acidic soil [Typic Haploxeralf; field capacity, 6.65 g H2O/100 g soil; pHw (1/2.5, w/v), 6.2; texture USDA, sandy loam, with illite as the predominant clay; oxidizable organic carbon 0.29%; extractable P, 19.9 mg/kg] and a calcareous soil [Typic Calcixerept; field capacity, 20.5 g H2O/100 g soil; pHw (1/2.5, w/v), 8.2; texture USDA, loamy sand, with smectite as the predominant clay; oxidizable organic carbon 0.75%; extractable P, 12.6 mg/kg]. These soils were treated with a synthetic chelate, Zn-ethylenediaminetetraacetate (Zn-EDTA), at different rates of application [0 (nil-Zn), 5 and 10 mg Zn kg-1 soil]. The potential available Zn concentrations were estimated at four experimental times (0, 15, 45 and 75 d) by the Mehlich-3 and DTPA-AB extraction methods. The results obtained showed the evolution of available Zn over experimental time, for each treatment. The Zn concentrations in both soils showed significant differences over experimental time. Zn-EDTA applied at both Zn rates (5 and 10 mg Zn kg-1) was associated with high variations in available Zn concentrations. However, in both soils, the decreases in available Zn

  4. High temperature dissolution of ferrites, chromites and bonaccordite in chelating media

    Energy Technology Data Exchange (ETDEWEB)

    Sathyaseelan, V.S.; Subramanian, H.; Anupkumar, B.; Rufus, A.L.; Velmurugan, S.; Narasimhan, S.V., E-mail: snv@igcar.gov.in [BARC Facilities, Water and Steam Chemistry Div., Tamilnadu (India)

    2010-07-01

    Different methods have been employed world wide for the decontamination of reactor coolant system surfaces. The success of a decontamination process mainly depends on the oxide dissolution efficiency of the decontamination formulation. Among the oxides, Fe{sub 3}O{sub 4} undergoes easy dissolution in organic acid media at normal temperatures. However, dissolution of chromites and mixed ferrites is not that easy in organic chelant media at normal temperatures even in the presence of redox reagents. Hence, a high temperature process was attempted for the dissolution of ferrites and chromites. A re-circulation system consisting of an autoclave, pump, heat exchanger etc. all lined with teflon was used for carrying out high temperature dissolution experiments. This study describes the high temperature dissolution kinetics of Fe{sub 3}O{sub 4}, NiFe{sub 2}O{sub 4}, and Cr{sub 2}O{sub 3}. Nitrilotriacetic acid (NTA), a well known solvent for metal oxides, was applied at temperatures ranging from 80 to 180{sup o}C. About six fold increase in dissolution rate was observed for Fe{sub 3}O{sub 4} in this temperature range. Effect of N{sub 2}H{sub 4} on oxide dissolution was studied. Lower dissolution rates were observed for Fe{sub 3}O{sub 4} and NiFe{sub 2}O{sub 4} in the presence of hydrazine. Oxide dissolution efficiency of other chelating agents like EDTA, PDCA etc. and the effect of reducing agents like oxalic acid and ascorbic acid on high temperature dissolution also has been studied. The effect of incorporation of boron and zinc in the iron and chromium oxides has also been studied. Bonaccordite (Ni{sub 2}FeBO{sub 5}) has been observed in the fuel deposits of pressurized Water Reactors especially in the AOA affected plants. Zinc ferrite/chromite are formed in reactors adopting zinc injection passivation technique to control radiation field. Bonaccordite and zinc ferrite/chromite formed over the reactor coolant system structural materials are also difficult to dissolve

  5. 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

  6. Preparation of chitosan-EDTA nanoparticles and the chelating effect of radioactive strontium in vivo

    International Nuclear Information System (INIS)

    Shu Hongzao; Liu Min; Wang Daojin; Yng Dan; Bai Jie; Xu Yujie

    2010-01-01

    Objective: To obtain the CTS-EDTA nanoparticles and investigate their effects of chelating 89 Sr 2+ in vivo. Method: The CTS-EDTA nanoparticles were prepared by cross-linking CTS-EDTA with polyanion sodium tripolyphosphate ( TPP). And the zwitterionic chelate of the CTS-EDTA nanoparticles was used for promoting the radionuclides excreted in vivo. Results: The CTS-EDTA nanoparticles showed that particle size was uniformity of the spherical nano-particles by TEM, and the average particle size of 10.18 nm by Laser Particle Sizer. we found that CEC-Nano and the CEC had a good chelating effect of radioactive strontium in vivo, after 30 min and 2 h in the medication and the chelating efficiency of radioactive strontium excretion in the femur was significantly higher than the EDTA-Na 2 . At multiple doses,the chelating efficiency of CEC-Nano and the CEC through the urinary excretion and feces were better than traditional medicines EDTA-Na 2 . Conclusion: By this experimental method, we can be prepare nanodrugs of chelating radionuclide, it provides a basis for studying the broad-spectrum of radionuclide contamination chelating agents. (authors)

  7. MRI marrow observations in thalassemia: the effects of the primary disease, transfusional therapy, and chelation

    Energy Technology Data Exchange (ETDEWEB)

    Levin, T.L. [Department of Pediatric Radiology, Columbia-Presbyterian Medical Center, Babies and Children`s Hospital, New York, NY (United States); Sheth, S.S. [Department of Pediatrics, Columbia-Presbyterian Medical Center, Babies and Children`s Hospital, 3959 Broadway, New York, NY 10032 (United States); Ruzal-Shapiro, C. [Department of Pediatric Radiology, Columbia-Presbyterian Medical Center, Babies and Children`s Hospital, New York, NY (United States); Abramson, S. [Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021 (United States); Piomelli, S. [Department of Pediatrics, Columbia-Presbyterian Medical Center, Babies and Children`s Hospital, 3959 Broadway, New York, NY 10032 (United States); Berdon, W.E. [Department of Pediatric Radiology, Columbia-Presbyterian Medical Center, Babies and Children`s Hospital, New York, NY (United States)

    1995-11-01

    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.

  8. 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.

  9. 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)

  10. Laser-induced breakdown spectroscopy & enrichment by chelation

    NARCIS (Netherlands)

    Roosma, J.R.; Veen, J.J.F. van

    2012-01-01

    LIBS is used for fast, multi-component analysis of element compositions, but it is not very suitable for liquids. Moreover the sensitivity for metal ions is often insufficient. A fast and sensitive detection tool for metal ions in food matrices, including aqueous solutions, is developed. The

  11. Inhibitor Ranking Through QM based Chelation Calculations for Virtual Screening of HIV-1 RNase H inhibition

    DEFF Research Database (Denmark)

    Poongavanam, Vasanthanathan; Svendsen, Casper Steinmann; Kongsted, Jacob

    2014-01-01

    of the methods based on the use of a training set of molecules, QM based chelation calculations were used as filter in virtual screening of compounds in the ZINC database. By this, we find, compared to regular docking, QM based chelation calculations to significantly reduce the large number of false positives......Quantum mechanical (QM) calculations have been used to predict the binding affinity of a set of ligands towards HIV-1 RT associated RNase H (RNH). The QM based chelation calculations show improved binding affinity prediction for the inhibitors compared to using an empirical scoring function...

  12. AAZTA: an ideal chelating agent for the development of {sup 44}Sc PET imaging agents

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, Gabor; Szikra, Dezso; Trencsenyi, Gyoergy [Scanomed Ltd., Debrecen (Hungary); University of Debrecen, Medical Imaging Clinic (Hungary); Fekete, Aniko [University of Debrecen, Medical Imaging Clinic (Hungary); Garai, Ildiko [Scanomed Ltd., Debrecen (Hungary); Giani, Arianna M.; Negri, Roberto [Dipartimento di Scienze del Farmaco, Universita del Piemonte Orientale, Novara (Italy); Masciocchi, Norberto [Dipartimento di Scienza e Alta Tecnologia e To.Sca.Lab, Universita degli Studi dell' Insubria, Como (Italy); Maiocchi, Alessandro; Uggeri, Fulvio [Bracco Imaging spa, Bracco Research Centre, Colleretto Giacosa (Italy); Toth, Imre [Department of Inorganic and Analytical Chemistry, University of Debrecen (Hungary); Aime, Silvio [Dipartimento di Biotecnologie Molecolari e Scienze della Salute, Centro di Imaging Molecolare e Preclinico, Universita degli Studi di Torino (Italy); Giovenzana, Giovanni B. [Dipartimento di Scienze del Farmaco, Universita del Piemonte Orientale, Novara (Italy); CAGE Chemicals srl, Novara (Italy); Baranyai, Zsolt [Bracco Imaging spa, Bracco Research Centre, Colleretto Giacosa (Italy); Department of Inorganic and Analytical Chemistry, University of Debrecen (Hungary)

    2017-02-13

    Unprecedented fast and efficient complexation of Sc{sup III} was demonstrated with the chelating agent AAZTA (AAZTA=1,4-bis(carboxymethyl)-6-[bis(carboxymethyl)] amino-6-methylperhydro-1,4-d iazepine) under mild experimental conditions. The robustness of the {sup 44}Sc(AAZTA){sup -} chelate and conjugated biomolecules thereof is further shown by in vivo PET imaging in healthy and tumor mice models. The new results pave the way towards development of efficient Sc-based radiopharmaceuticals using the AAZTA chelator. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. 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.

  14. Some problems of synthesis of coordination compounds - the molecular predecessors of metal sulfides

    International Nuclear Information System (INIS)

    Larionov, S.V.

    1996-01-01

    Processes of metal sulfide preparations which require preliminary synthesis of coordination compounds o the metals (Cd, In, etc.) with organic sulfur-containing ligands have been considered. The promising trends in the synthesis are as follows: synthesis of chelate compounds and salts with rationally selected anions; synthesis of different-ligand compounds; synthesis of precursors for complex sulfides preparation. 14 refs

  15. Platinum metal chemistry of bisphosphines derived from N,N ...

    Indian Academy of Sciences (India)

    Administrator

    Platinum metal chemistry of bisphosphines derived from. N,N¢-substituted ethylenediamine derivatives. RITA M ABHYANKAR and M S BALAKRISHNA. Department of Chemistry, Indian Institute of Technology Bombay, Powai,. Mumbai 400 076, India. The role of chelate complexes containing bisphosphine ligands in ...

  16. Thiosemicarbazone complexes of the platinum metals. A story of ...

    Indian Academy of Sciences (India)

    , Os; X = Cl, Br) to afford complexes of type [M(PPh3)2(Hsaltsc)2], in which the salicylaldehyde thiosemicarbazone ligand is coordinated to the metal as a bidentate N,S-donor forming a four-membered chelate ring. Reaction of benzaldehyde ...

  17. Chelatable trace zinc causes low, irreproducible KDAC8 activity.

    Science.gov (United States)

    Toro, Tasha B; Edenfield, Samantha A; Hylton, Brandon J; Watt, Terry J

    2018-01-01

    Acetylation is an important regulatory mechanism in cells, and emphasis is being placed on identifying substrates and small molecule modulators of this post-translational modification. However, the reported in vitro activity of the lysine deacetylase KDAC8 is inconsistent across experimental setups, even with the same substrate, complicating progress in the field. We detected trace levels of zinc, a known inhibitor of KDAC8 when present in excess, even in high-quality buffer reagents, at concentrations that are sufficient to significantly inhibit the enzyme under common reaction conditions. We hypothesized that trace zinc in solution could account for the observed variability in KDAC8 activity. We demonstrate that addition of chelators, including BSA, EDTA, and citrate, and/or the use of a phosphate-based buffer instead of the more common tris-based buffer, eliminates the inhibition from low levels of zinc as well as the dependence of specific activity on enzyme concentration. This results in high KDAC8 activity that is consistent across buffer systems, even using low concentrations of enzyme. We report conditions that are suitable for several assays to increase both enzyme activity and reproducibility. Our results have significant implications for approaches used to identify substrates and small molecule modulators of KDAC8 and interpretation of existing data. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. ATMP-stabilized iron nanoparticles: chelator-controlled nanoparticle synthesis

    Science.gov (United States)

    Greenlee, Lauren F.; Rentz, Nikki S.

    2014-11-01

    In this study, we characterize iron nanoparticles synthesized in water in the presence of a phosphonate chelator, amino tris(methylene phosphonic acid) (ATMP) for a range of molar ratios of ATMP to iron. An increase in the molar ratio from 0.05 to 0.8 decreases nanoparticle size from approximately 150 nm to less than 10 nm. Zeta potential measurements were used to evaluate colloidal stability. Zeta potential values varied as a function of pH, and zeta potential values decreased with increasing pH. At lower molar ratios of ATMP to iron, the zeta potential varied between 15 and -40 mV, passing through an isoelectric point at pH 7.5. At higher ratios, the zeta potential was negative across the measured pH range of 2-12 and varied from -2 to -55 mV. Diffraction analysis indicates that ATMP-stabilized iron nanoparticles may have a nano-crystalline structure, potentially with regions of amorphous iron. Characterization results of ATMP-stabilized iron nanoparticles are compared to results obtained for carboxymethyl cellulose (CMC)-stabilized iron nanoparticles. CMC stabilization caused similar peak broadening in diffraction spectra as for ATMP, suggesting similar nano-crystalline/amorphous structure; however, an increase in the molar ratio of CMC to iron did not cause the same reduction in nanoparticle size as was observed for ATMP-stabilized iron nanoparticles.

  19. 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)

  20. Comparison of Kinetic Study and Protective Effects of Biological Dipeptide and Two Porphyrin Derivatives on Metal Cytotoxicity Toward Human Lymphocytes.

    Science.gov (United States)

    Khosravi, Maryam; Rahimi, Rahmatollah; Pourahmad, Jalal; Zarei, Mohammad Hadi; Rabbani, Mahboubeh

    2017-01-01

    In this research, dipeptide (his- β -alanine) and porphyrin derivatives were choosen for comparing chelating ability of toxic metals such as Al 3+ , Cu 2+ , Hg 2+ and Pb 2 + in-vitro . The reason for choosing these two compounds is that both of them are naturally present in biological systems and comparison of chelating ability of these two compounds has not yet been done. Synthesis and comparison of kinetic study of dipeptide (his- β -alanine), meso-tetrakis(4-trimethylanilinium) porphyrin (TAPP) and Tetrakis(4-sulfonatophenyl)porphyrin (TPPS 4 ) were carried out by our team. In addition, cytotoxicity assays of metals and chelators were also performed using methylthiazoletetrazolium (MTT) test. Furthermore we investigated the protective effect of chelators against cytotoxicity, induced by differenrt toxic metals such as Al 3+ , Cu 2+ , Hg 2+ and Pb 2+ on human lymphocytes. EC 50 values on human lymphocytes obtained after 12 h. incubation for Al 3+ , Cu 2+ and Hg 2+ were 30, 51, 3 µM respectively and for Pb 2+ no cytotoxicity was observed on human lymphocyte up to 1000 µM concentration. EC 50 obtained for chelators dipeptide, TPPS 4 and TAPP were 948, 472 and 175 µM respectively. Pretreatment of human lymphocyte with subtoxic concentations of chelators reduced toxicity of the metals against human blood lymphocytes.

  1. 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.

  2. The performance of 2-nitroso-1-naphthol chelating pigment in paint ...

    African Journals Online (AJOL)

    The performance of 2-nitroso-1-naphthol chelating pigment in paint formulation with gum Arabic and polyvinyl acetate as binders, Paper I: UV- visible spectroscopy, viscosity and breaking stress of the paints.

  3. Iron chelation therapy in transfusion-dependent thalassemia patients: current strategies and future directions

    Directory of Open Access Journals (Sweden)

    Saliba AN

    2015-06-01

    Full Text Available Antoine N Saliba, Afif R Harb, Ali T Taher Department of Internal Medicine, Division of Hematology/Oncology, American University of Beirut, Beirut, Lebanon Abstract: Transfusional iron overload is a major target in the care of patients with transfusion-dependent thalassemia (TDT and other refractory anemias. Iron accumulates in the liver, heart, and endocrine organs leading to a wide array of complications. In this review, we summarize the characteristics of the approved iron chelators, deferoxamine, deferiprone, and deferasirox, and the evidence behind the use of each, as monotherapy or as part of combination therapy. We also review the different guidelines on iron chelation in TDT. This review also discusses future prospects and directions in the treatment of transfusional iron overload in TDT whether through innovation in chelation or other therapies, such as novel agents that improve transfusion dependence. Keywords: thalassemia, transfusion-dependent thalassemia, iron overload, iron chelation therapy, transfusion

  4. A Zinc Chelator TPEN Attenuates Airway Hyperresponsiveness Airway Inflammation in Mice In Vivo

    Directory of Open Access Journals (Sweden)

    Satoru Fukuyama

    2011-01-01

    Conclusions: In pulmonary allergic inflammation induced in mice immunized with antigen without alum, zinc chelator inhibits airway inflammation and hyperresponsiveness. These findings suggest that zinc may be a therapeutic target of allergic asthma.

  5. Bifunctional chelates of RH-105 and AU199 as potential radiotherapeutic agents

    Energy Technology Data Exchange (ETDEWEB)

    Droege, P.

    1997-03-01

    Research is presented on new bifunctional chelating ligand systems with stability on the macroscopic and radiochemical levels. The synthesis of the following complexes are described: rhodium 105, palladium 109, and gold 198.

  6. Absorption of nitric oxide into aqueous solutions of ferrous chelates accompanied by instantaneous reaction

    NARCIS (Netherlands)

    Demmink, J.F; vanGils, I.C.F.; Beenackers, A.A C M

    1997-01-01

    The absorption of nitric oxide (NO) into aqueous solutions of ferrous chelates of nitrilotriacetic acid (NTA), ethylene diaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), and diethylenetriaminepentaacetic acid (DTPA) was studied in a stirred cell reactor. Experimental

  7. Trace metal speciation and bioavailability in anaerobic digestion: A review.

    Science.gov (United States)

    Thanh, Pham Minh; Ketheesan, Balachandran; Yan, Zhou; Stuckey, David

    2016-01-01

    Trace metals are essential for the growth of anaerobic microorganisms, however, in practice they are often added to anaerobic digesters in excessive amounts, which can lead to inhibition. The concept of bioavailability of metals in anaerobic digestion has been poorly understood in the past, and a lack of deep understanding of the relationship between trace metal speciation and bioavailability can result in ineffective metal dosing strategies for anaerobic digesters. Sequential extraction schemes are useful for fractionating trace metals into their different forms, and metal sulfides can serve as a store and source for trace metals during anaerobic digestion, while natural/synthetic chelating agents (soluble microbial products-SMPs, extracellular polysaccharides-EPS, and EDTA/NTA) are capable of controlling trace metal bioavailability. Nevertheless, more work is needed to: investigate the speciation and bioavailability of Ca, Mg, Mn, W, and Se; compare the bioavailability of different forms of trace metals e.g. carbonates, sulfides, phosphates to different anaerobic trophic groups; determine what factors influence metal sulfide dissolution; investigate whether chelating agents can increase trace metal bioavailability; develop and adapt specialized analytical techniques, and; determine how trace metal dynamics change in an anaerobic membrane bioreactor (AnMBR). Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Synthesis of gold nanoparticles stabilised by metal-chelator and the ...

    Indian Academy of Sciences (India)

    Unknown

    The surface plasmon band of nanoparticles is very sensitive not only to their size and shape but also to the inter-particle distance. In aggregated state, the individual nano- particles can interact with each another and give rise to oscillations that are combinations of oscillations of individual nanoparticles.14 This causes red ...

  9. Emulsifier type, metal chelation and pH affect oxidative stability of n-3-enriched emulsions

    DEFF Research Database (Denmark)

    Haahr, Anne-Mette; Jacobsen, Charlotte

    2008-01-01

    -enriched oil-in-water emulsion. The selected food emulsifiers were Tween 80, Citrem, sodium caseinate and lecithin. Lipid oxidation was evaluated by determination of peroxide values and secondary volatile oxidation products. Moreover, the zeta potential and the droplet sizes were determined. Twen resulted...... in the least oxidatively stable emulsions, followed by Citrem. When iron was present, caseinate-stabilized emulsions oxidized slower than lecithin emulsions at pH 3, whereas the opposite was the case at pH 7. Oxidation generally progressed faster at pH 3 than at pH 7, irrespective of the addition of iron. EDTA...

  10. Excited State Evolution towards ligand loss and ligand chelation at group 6 metal carbonyl centres

    NARCIS (Netherlands)

    Manton, J.C.; Amirjalayer, S.; Coleman, A.C.; McMahon, S.; Harvey, E.C.; Greetham, G.M.; Clark, I.P.; Buma, W.J.; Woutersen, S.; Pryce, M.T.; Long, C.

    2014-01-01

    The photochem. and photophysics of three model "half-​sandwich" complexes (η6-​benzophenone)​Cr(CO)​3, (η6-​styrene)​Cr(CO)​3, and (η6-​allylbenzene)​Cr(CO)​3 were investigated using pico-​second time-​resolved IR spectroscopy and time-​dependent d. functional theory methods. The

  11. Degradation of polycyclic aromatic hydrocarbons by hydrogen peroxide catalyzed by heterogeneous polymeric metal chelates

    Czech Academy of Sciences Publication Activity Database

    Baldrian, Petr; Cajthaml, Tomáš; Merhautová, Věra; Gabriel, Jiří; Nerud, František; Stopka, P.; Hrubý, Martin; Beneš, Milan J.

    2005-01-01

    Roč. 59, - (2005), s. 267-274 ISSN 0926-3373 R&D Projects: GA AV ČR IBS5020306; GA ČR GA203/01/0944 Institutional research plan: CEZ:AV0Z7090911 Keywords : degradation * polycyclic aromatic hydrocarbon * hydrogen peroxide Subject RIV: EE - Microbiology, Virology Impact factor: 3.809, year: 2005

  12. Is Chelation Therapy Efficient for the Treatment of Intravenous Metallic Mercury Intoxication?

    Czech Academy of Sciences Publication Activity Database

    Pelclová, D.; Vlčková, Š.; Bezdíček, O.; Vaněčková, M.; Urban, P.; Ridzoň, P.; Diblik, P.; Navrátil, Tomáš; Klusáčková, P.; Vlček, K.; Benešová, O.; Třeštík, P.; Homolka, J.; Zakharov, S.

    2017-01-01

    Roč. 120, č. 6 (2017), s. 628-633 ISSN 1742-7835 Institutional support: RVO:61388955 Keywords : elemental mercury * injection * children Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.176, year: 2016

  13. Rapid anaerobic benzene oxidation with a variety of chelated Fe(III) forms

    Science.gov (United States)

    Lovley, D.R.; Woodward, J.C.; Chapelle, F.H.

    1996-01-01

    Fe(III) chelated to such compounds as EDTA, N-methyliminodiacetie acid, ethanol diglycine, humic acids, and phosphates stimulated benzene oxidation coupled to Fe(III) reduction in anaerobic sediments from a petroleum- contaminated aquifer as effectively as or more effectively than nitrilotriacetic acid did in a previously demonstrated stimulation experiment. These results indicate that many forms of chelated Fe(III) might be applicable to aquifer remediation.

  14. Predictors of dimercaptosuccinic acid chelatable lead and tibial lead in former organolead manufacturing workers

    OpenAIRE

    Schwartz, B. S.; Stewart, W. F.; Todd, A. C.; Links, J. M.

    1999-01-01

    OBJECTIVES: To identify predictors of tibial and dimercaptosuccinic acid (DMSA) chelatable lead in 543 organolead manufacturing workers with past exposure to organic and inorganic lead. METHODS: In this cross sectional study, tibial lead (by 109Cd K-shell x ray fluorescence), DMSA chelatable lead (4 hour urinary lead excretion after oral administration of 10 mg/kg), and several exposure measures were obtained on study participants, mean (SD) age 57.6 (7.6) years. RESULTS: Tibial lead co...

  15. The iron chelator deferasirox protects mice from mucormycosis through iron starvation

    OpenAIRE

    Ibrahim, Ashraf S.; Gebermariam, Teclegiorgis; Fu, Yue; Lin,, Lin; Husseiny, Mohamed I.; French, Samuel W.; Schwartz, Julie; Skory, Christopher D.; Edwards, John E.; Spellberg, Brad J.

    2007-01-01

    Mucormycosis causes mortality in at least 50% of cases despite current first-line therapies. Clinical and animal data indicate that the presence of elevated available serum iron predisposes the host to mucormycosis. Here we demonstrate that deferasirox, an iron chelator recently approved for use in humans by the US FDA, is a highly effective treatment for mucormycosis. Deferasirox effectively chelated iron from Rhizopus oryzae and demonstrated cidal activity in vitro against 28 of 29 clinical...

  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. 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.)

  18. 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

  19. Advances in iron chelation therapy: transitioning to a new oral formulation

    Directory of Open Access Journals (Sweden)

    Nirmish R Shah

    2017-06-01

    Full Text Available Iron overload is a concern for patients who require repeated red-blood-cell transfusions due to conditions such as sickle cell disease, thalassemia, or myelodysplastic syndromes. The recommended treatment for removing excess iron in these patients is iron chelation therapy. Currently available iron chelators include deferoxamine, which is administered by injection, and deferasirox and deferiprone, both of which are administered orally. Adherence to iron chelator therapy is an important consideration and may be affected by side effects. A new formulation of deferasirox, a film-coated tablet (FCT, has the potential to improve adherence by offering greater flexibility in administration compared with the original formulation of deferasirox, a dispersible tablet (DT for oral suspension. This review provides an overview of the currently available iron chelator formulations, with a focus on a comparison between deferasirox DT for oral suspension and deferasirox FCT. The new formulation may be associated with fewer side effects and has increased bioavailability. In addition, alternative strategies for iron chelation, such as combining two different iron chelators, will be discussed.

  20. Advances in iron chelation therapy: transitioning to a new oral formulation.

    Science.gov (United States)

    Shah, Nirmish R

    2017-01-01

    Iron overload is a concern for patients who require repeated red-blood-cell transfusions due to conditions such as sickle cell disease, thalassemia, or myelodysplastic syndromes. The recommended treatment for removing excess iron in these patients is iron chelation therapy. Currently available iron chelators include deferoxamine, which is administered by injection, and deferasirox and deferiprone, both of which are administered orally. Adherence to iron chelator therapy is an important consideration and may be affected by side effects. A new formulation of deferasirox, a film-coated tablet (FCT), has the potential to improve adherence by offering greater flexibility in administration compared with the original formulation of deferasirox, a dispersible tablet (DT) for oral suspension. This review provides an overview of the currently available iron chelator formulations, with a focus on a comparison between deferasirox DT for oral suspension and deferasirox FCT. The new formulation may be associated with fewer side effects and has increased bioavailability. In addition, alternative strategies for iron chelation, such as combining two different iron chelators, will be discussed.

  1. Chelating effect of silver nitrate by chitosan on its toxicity and growth performance in broiler chickens

    Directory of Open Access Journals (Sweden)

    Yemdjie Mane Divine Doriane

    2017-06-01

    Full Text Available Objective: This study was conducted to investigate the chelating effect of silver nitrate (AgNO3 by chitosan on growth performances, hematological and biochemical parameters, and the histopathological structure of the liver and the kidney in broiler chicken. Materials and methods: A total of 192 day-old Cobb 500 strain chicks were randomly assigned to 3 treatments of 64 chicks each. Control group was fed on basal diet without supplement (R0 and the two others groups were fed on rations supplemented with 10 mg of unchelated (RAg or chelated (RCs-Ag AgNO3 per Kg of feed, respectively. Parameters that have been studied consisted of feed intake, weight gain, blood and serum biochemical, and histopathological analyses of liver and kidney. Results: Results revealed that chelation of AgNO3 by chitosan did not have any effect on growth performances and hematological parameters in chicken. However, chelated and unchelated AgNO3 increased the serum content in triglyceride, and cholesterol and decreased the serum content in creatinin, albumin and alanine aminotransferase (ALAT. Chelating AgNO3 with chitosan prevented and corrected the toxicity induced on the histological structure of liver and kidney. Conclusion: Chitosan can be used as a chelating agent to alleviate the harmful effects of AgNO3 as silver ion for poultry. [J Adv Vet Anim Res 2017; 4(2.000: 187-193

  2. 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.

  3. In vitro and in vivo evaluation of the bifunctional chelator NODIA-Me in combination with a prostate-specific membrane antigen targeting vector.

    Science.gov (United States)

    Läppchen, Tilman; Kiefer, Yvonne; Holland, Jason P; Bartholomä, Mark D

    2018-03-10

    We recently developed a chelating platform based on the macrocycle 1,4,7-triazacyclononane with up to three five-membered azaheterocyclic arms for complexation of the PET nuclides gallium-68 and copper-64. The main objective of this study was to evaluate the stability and pharmacokinetics of 68 Ga- and 64 Cu-complexes of the bifunctional chelator NODIA-Me 1 covalently bound to a PSMA targeting vector in vivo. NODIA-Me 1 was conjugated to the PSMA targeting Glu-NH-CO-NH-Lys moiety to give the bioconjugate NODIA-Me-NaI-Ahx-PSMA 4. The stability of [ 68 Ga]4 and [ 64 Cu]4 was assessed in vitro by serum stability studies. The PSMA binding affinity was determined in competitive cell experiments in LNCaP cells using 68 Ga-PSMA-HBED-CC as radioligand. The stability and pharmacokinetics of [ 68 Ga]4 and [ 64 Cu]4 was evaluated by PET imaging and ex vivo biodistribution studies in mice bearing subcutaneous LNCaP tumors. In human serum, [ 68 Ga]4 and [ 64 Cu]4 remained intact to 85% (3 h) and 92% (24 h), respectively. Nature of the metal chelate influenced PSMA binding affinity with IC 50 of 233 ± 10 nM for uncomplexed 4, 681 ± 7 nM for Cu-4 and 176 ± 10 nM for Ga-4. In animal studies, [ 68 Ga]4 and [ 64 Cu]4 revealed low uptake (≤1% IA g -1 ) in the majority of organs. Kidney uptake at 1 h p.i. was 6.28 ± 0.92% IA g -1 and 4.96 ± 0.79% IA g -1 and specific tumor uptake was 1.33 ± 0.46% IA g -1 and 2.15 ± 0.38% IA g -1 for [ 68 Ga]4 and [ 64 Cu]4, respectively. The bifunctional chelator NODIA-Me 1 was successfully conjugated to a PSMA targeting moiety. In small-animal PET imaging and ex vivo biodistribution studies, 68 Ga- and 64 Cu-labelled conjugates specifically delineated PSMA-positive LNCaP tumors and exhibited rapid renal clearance from non-target tissues with no significant demetallation/transchelation in vivo. The results support further development of this novel chelating platform for production of 68 Ga- and 64 Cu

  4. Efficacy of intramuscular and intraperitoneal deferoxamine for aluminum chelation.

    Science.gov (United States)

    Molitoris, B A; Alfrey, P S; Miller, N L; Hasbargen, J A; Kaehney, W D; Alfrey, A C; Smith, B J

    1987-04-01

    As intravenous administration of deferoxamine is difficult in home dialysis patients we set out to determine the efficacy of intramuscular (i.m.) and intraperitoneal (i.p.) deferoxamine for removal of aluminum. Patients with serum aluminum levels greater than 90 micrograms/liter were studied in a paired fashion with each patient serving as their own control. Serum and peritoneal fluid aluminum were determined using flameless atomic absorption. In hemodialysis patients 2 g of intravenous deferoxamine increased serum aluminum from 124.7 +/- 32.4 to 415 +/- 192.4 micrograms/liter. One g of deferoxamine given intravenously or intramuscularly resulted in 76.8 +/- 35.3% and 70.4 +/- 23.2%, respectively, of the 2 g i.v. response. The rate at which serum aluminum increased following i.v. deferoxamine infusion was biphasic, with an initial rapid phase lasting 139 minutes followed by a much slower phase. The volume of distribution of aluminum following deferoxamine administration was 12.6 +/- 1.61 and the half life (t1/2) for aluminum removal during hemodialysis was 9.0 +/- 2.0 hours. The increase in serum aluminum following deferoxamine was not due to chelation of erythrocyte aluminum as erythrocyte aluminum remained constant over 24 hours. In patients on continuous ambulatory peritoneal dialysis, 2 g intravenous deferoxamine resulted in the removal of 560 +/- 267 micrograms of aluminum over 24 hours while 2 g deferoxamine given intraperitoneally gave 91 +/- 13% of the intravenous response. Aluminum clearance over 48 hours was twice that for 24 hours for both i.v. and i.p. deferoxamine.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Resinas quelantes amidoxímicas Amidoxime chelating resins

    Directory of Open Access Journals (Sweden)

    Fernanda M. B. Coutinho

    1999-12-01

    Full Text Available Resinas quelantes com grupos amidoxima foram sintetizadas por copolimerização em suspensão de acrilonitrila (AN e divinilbenzeno (DVB e subsequente modificação química dos grupos ciano por reação com hidroxilamina. Na copolimerização, a proporção de divinilbenzeno e o grau de diluição foram variados. Gelatina e carbonato de cálcio foram usados como estabilizadores de suspensão e sulfato de sódio foi adicionado para reduzir a solubilidade da acrilonitrila em água, por meio do efeito salting out. Os copolímeros de AN/DVB e as resinas amidoxímicas obtidos foram caracterizados por meio de densidade aparente, área específica, volume de poros e teor de nitrogênio. As resinas amidoxímicas foram também avaliadas em relação a capacidade de complexação de íons cobre.Chelating resins with amidoxime groups were synthesized by suspension copolymerization of acrylonitrile (AN and divinylbenzene (DVB and subsequent chemical modification of cyano groups by reaction with hydroxylamine. In the copolymerization, the proportion of divinylbenzene and the dilution degree were varied. Gelatin and calcium carbonate were used as suspension stabilizers and sodium sulphate was added in order to reduce acrylonitrile solubility in water, by salting out effect. The AN/DVB copolymers and amidoxime resins obtained were characterized by apparent density, surface area, pore volume and by the content of nitrogen. The amidoxime resins were also evaluated in relation to the complexation capacity of copper ion.

  6. A simple and rapid method for isotopic analysis of nickel, copper, and zinc in seawater using chelating extraction and anion exchange.

    Science.gov (United States)

    Takano, Shotaro; Tanimizu, Masaharu; Hirata, Takafumi; Shin, Ki-Cheol; Fukami, Yusuke; Suzuki, Katsuhiko; Sohrin, Yoshiki

    2017-05-15

    Stable isotope ratios of nickel, copper, and zinc are powerful tools for elucidating the biogeochemical cycling of trace metals in the ocean. However, analytical difficulties have impeded isotopic studies of these metals. We present a simple and rapid method for simultaneous analysis of Ni, Cu, and Zn isotope ratios in seawater using NOBIAS Chelate-PA1 resin and anion exchange resin. A NOBIAS Chelate-PA1 resin column was used to quantitatively collect Ni, Cu, and Zn from seawater and thoroughly remove the seawater matrix. Subsequent anion exchange purified and separated the Ni, Cu, and Zn from each other. The blanks used in this method (0.22 ng for Ni, 0.29 ng for Cu, and 0.53 ng for Zn) were sufficiently low to determine the isotope ratios of Ni, Cu, and Zn in surface seawater. Using this method, we analyzed GEOTRACES reference seawater samples (i.e., SAFe D1 and SAFe D2), National Research Council Canada certified materials (i.e., CASS-5 and NASS-6), and seawater samples collected from different depths in the subarctic South Pacific. The results were consistent with previously reported values. This method is expected to accelerate isotopic research and contribute to our understanding of biogeochemical cycling in the ocean. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Response of Different Irrigation on Nano Iron Chelated to Chamomile (Matricaria Chamomilla L. Genotypes

    Directory of Open Access Journals (Sweden)

    hamideh azade godjebigloo

    2017-12-01

    Full Text Available To study the effects of drought stress and foliar application of nano iron chelated on photosynthetic pigments, yield and yield component of thirteen genotypes of chamomile, a factorial experiment was conducted in a randomized complete block design with three replications at the Research Greenhouse of Zabol University in 2014. The experimental treatments were: drought stress at 2 levels (control or irrigation at 90% of field capacity and irrigation at 70% of field capacity, foliar application of nano iron chelate at 2 levels (control and 2 mg/l and 13 genotypes of chamomile consisting at: Isfahan, Mashhad, Shiraz, Kerman, Arak, Ardestan, Gachsaran, Nain, Khozestan, Safashahr, Kazeroon, Germany and Hungary. The results showed that besides the main effects of stress×genotype, the genotype×nano iron chelated and stress×nano iron chelated interactions and the triple effects were also became significant. Mean comparisons showed that the condition of genotypes at any level of stress and nano iron chelated had different trends. Using nano iron chelated in drought stress decreased chlorophyll a in Shiraz, Khozestan, Nain, Hungary and Germany genotypes, decreased chlorophyll b in genotypes of Isfahan, Kazeroon, Ardestan, Khozestan, Nain and Germany, decreased total chlorophyll in genotypes of Isfahan, Shiraz, Ardestan, Khozestan, Nain, Hungary and Germany and decreased anthocyanin content in Isfahan, Shiraz, Safashahr, Kazeroon, Khozestan and Germany genotypes. Using nano iron chelated in drought stress also caused a decrease in flower yield of Mashhad, Arak and Nain and a decrease per plant yield of Isfahan, Mashhad, Arak, Safashahr, Khozestan and Nain genotypes. The highest per plant yield (0.665 g. belonged to Kerman genotype, were achieved through non-stress and use of nano iron chelate treatments and the lowest per plant yield (0.164 g. to Arak genotype through the stress and non-spray treatments. Totally the interaction of chamomile genotypes to

  8. 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 the treatments (NTA = 1, EDTA / NTA = 1: 2). The nutrient element TN was decreased most, reaching 51.6%, and the activation effect was decreased significantly in the fifteenth day in treatment (NTA = 1), Treatment(EDTA / NTA = 1: 1)> 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

  9. 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

  10. Tentacle-type immobilized metal affinity cryogel for invertase purification from Saccharomyces cerevisiae.

    Science.gov (United States)

    Çetin, Kemal; Perçin, Işık; Denizli, Fatma; Denizli, Adil

    2017-11-01

    The aim of this study is to investigate the usability of cryogel columns for the purification of invertase from Saccharomyces cerevisiae. Poly(2-hydroxyethyl methacrylate) monolithic columns were produced via cryogelation. Ester groups of the poly(2-hydroxyethyl methacrylate) structure were then converted to imine groups by the reaction with poly(ethylene imine) in the presence of NaHCO 3 . Transition metal ions, Cu(II), Co(II), and Ni(II), were chelated on the PEI-modified cryogel columns. Purification of invertase from natural source namely S. cerevisiae was also studied, and the purification fold values were obtained as 41.350, 44.714, and 30.302 for Cu(II)-chelated, Co(II)-chelated, and Ni(II)-chelated PHEMA/PEI columns, respectively.

  11. 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.

  12. 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

  13. Impact of a snail pellet on the phytoavailability of different metals to cucumber plants (Cucumis sativus L.).

    Science.gov (United States)

    Freitag, Sabine; Krupp, Eva M; Raab, Andrea; Feldmann, Jörg

    2013-02-01

    FePO4 based molluscicides (snail pellets) also contain a chelating agent. The influence of the chelating agent, which is intrinsically present in the molluscicide, on the phytoavailability of other metals present in the growth medium was investigated in the present study. Cucumber plants (Cucumis sativus) were grown in a hydroponic nutrient solution and exposed for one week to different metals in combination with a chelating agent containing molluscicide. Oven dried roots and shoots of plants were HNO 3/H2O2 microwave digested and analysed regarding total Fe, stable isotopic (54)Fe, Cd, Pb, and Bi concentrations using ICP-MS. The results showed that the addition of a chelating agent enhances the Fe phytoavailability to the plant, whether as an intrinsic part of the molluscicide or added individually. Additionally, the chelating agent present in the pesticide mobilises externally added metals and thus increases their phytoavailability. In particular the significantly higher Cd concentration in shoots from plants exposed to chelating agents indicates a potentially detrimental environmental effect.

  14. Inconsistent hepatic antifibrotic effects with the iron chelator deferasirox.

    Science.gov (United States)

    Sobbe, Amy; Bridle, Kim R; Jaskowski, Lesley; de Guzman, C Erika; Santrampurwala, Nishreen; Clouston, Andrew D; Campbell, Catherine M; Subramaniam, V Nathan; Crawford, Darrell H G

    2015-03-01

    Development of effective antifibrotic treatments that can be translated to clinical practice is an important challenge in contemporary hepatology. A recent report on β-thalassemia patients demonstrated that deferasirox treatment reversed or stabilized liver fibrosis independent of its iron-chelating properties. In this study, we investigated deferasirox in cell and animal models to better understand its potential antifibrotic effects. The LX-2 stellate cell line was treated with 5 μM or 50 μM deferasirox (Exjade, Novartis Pharmaceuticals Australia, North Ryde, NSW, Australia) for up to 120 h. Three-week-old multidrug resistance 2 null (Mdr2(-/-) ) mice received oral deferasirox or vehicle for 4 weeks (30 mg/kg/day). Cells and liver tissue were collected for assessment of fibrosis and fibrogenic gene expression. In LX-2 cells treated with 50 μM deferasirox for 12 h, α1(I)procollagen expression was decreased by 25%, with maximal reductions (10-fold) seen following 24-120 h of treatment. Similarly, α-smooth muscle actin (αSMA) expression was significantly lower. Alterations in matrix remodeling genes, specifically decreased expression of matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-2, were observed. There was no significant difference in hepatic hydroxyproline content in Mdr2(-/-) mice following deferasirox administration (vehicle: 395 ± 27 μg/g vs deferasirox: 421 ± 33 μg/g). Similarly, no changes in the expression of fibrogenic genes were observed. Despite reductions in α1(I)procollagen and αSMA expression and alterations in matrix degradation genes in LX-2 cells, deferasirox did not exhibit antifibrotic activity in Mdr2(-/-) mice. Given the positive outcomes seen in human trials, it may be appropriate to study deferasirox in other animal models of fibrosis and/or for a longer duration of therapy. © 2014 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.

  15. Antimicrobial Properties of Copper Nanoparticles and Amino Acid Chelated Copper Nanoparticles Produced by Using a Soya Extract

    OpenAIRE

    DeAlba-Montero, I.; Guajardo-Pacheco, Jes?s; Morales-S?nchez, Elpidio; Araujo-Mart?nez, Rene; Loredo-Becerra, G. M.; Mart?nez-Casta??n, Gabriel-Alejandro; Ruiz, Facundo; Compe?n Jasso, M. E.

    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 M...

  16. Synthesis, characterization and physicochemical studies of new chelating resin 1, 8-(3, 6-dithiaoctyl)-4-polyvinylbenzenesulphonate (dpvbs) and its metallopolymer Cu(II), Ni(II), Co(II) and Fe(III) complexes

    Science.gov (United States)

    Khalil, Tarek E.; Elbadawy, Hemmat A.; El-Dissouky, Ali

    2018-02-01

    A new chelating resin, 1,8-(3,6-dithiaoctyl)-4-polyvinylbenzenesulphonate (dpvbs) has been synthesized by coupling Amberlite XAD-16 with (2,2‧-ethylenedithio) diethanol using pyridine/CH2Cl2 mixture as a solvent. The chelating resin and its metallopolymer Cu(II), Ni(II), Co(II) and Fe(III) complexes have been synthesized and characterized by EDS, SEM, XPS, elemental analysis, spectral (IR, UV/Vis, EPR). The thermal analysis of the resin and its metallopolymer complexes indicated an endothermic spontaneous sorption mechanism with the liberation of water of hydration of the metal ions and that adsorbed by the free resin. At the solid liquid interface, the degrees of freedom increased during the sorption of the metal ions onto the resin. The surface area of polymer support and its metallopolymer complexes are estimated by (BJH) method. The batch equilibrium method was used for studying the metal sorption and selectivity at different pH values and different contact times at room temperature. ICP-AES was used to estimate the metal capacity of the resin for sorption of Cu(II), Ni(II), Co(II) and Fe(III) from aqueous solutions utilizing the batch equilibrium method. The sorption tendency of the metal ions by the resin was found to be: Cu(II) > Fe(III) > Co(II) > Ni(II). Adsorption kinetics was found to be fit the pseudo-second order model.

  17. 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.

  18. 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.

  19. Management of transfusional iron overload – differential properties and efficacy of iron chelating agents

    Directory of Open Access Journals (Sweden)

    Kwiatkowski JL

    2011-09-01

    Full Text Available Janet L Kwiatkowski The Children's Hospital of Philadelphia, Division of Hematology and University of Pennsylvania School of Medicine, Philadelphia, PA, USA Abstract: Regular red cell transfusion therapy ameliorates disease-related morbidity and can be lifesaving in patients with various hematological disorders. Transfusion therapy, however, causes progressive iron loading, which, if untreated, results in endocrinopathies, cardiac arrhythmias and congestive heart failure, hepatic fibrosis, and premature death. Iron chelation therapy is used to prevent iron loading, remove excess accumulated iron, detoxify iron, and reverse some of the iron-related complications. Three chelators have undergone extensive testing to date: deferoxamine, deferasirox, and deferiprone (although the latter drug is not currently licensed for use in North America where it is available only through compassionate use programs and research protocols. These chelators differ in their modes of administration, pharmacokinetics, efficacy with regard to organ-specific iron removal, and adverse-effect profiles. These differential properties influence acceptability, tolerability and adherence to therapy, and, ultimately, the effectiveness of treatment. Chelation therapy, therefore, must be individualized, taking into account patient preferences, toxicities, ongoing transfusional iron intake, and the degree of cardiac and hepatic iron loading. Keywords: transfusion, iron, chelation, magnetic resonance imaging

  20. Removal of thallium by combining desferrioxamine and deferiprone chelators in rats.

    Science.gov (United States)

    Amiri, Asghar; Fatemi, S Jamilaldine; Fatemi, S Nabilaldine

    2007-04-01

    The hypothesis that two known chelators deferiprone (1,2-dimethy1-3-hydroxypyrid-4-one, L1) and desferrioxamine (DFO) might be more efficient as combined treatment than as monotherapies in removing thallium from the body was tested in rats. Six-week-old male Wistar rats received chelators: L1 (p.o.), DFO (i.p.) or L1 + DFO as 110 or 220 mg/kg dose half an hour after a single i.p. administration of 8 mg Tl/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 L1 in enhancing urinary thallium excretion, L1 was more effective than DFO in enhancing urinary iron excretion. In the combined treatment group, L1 did not increase the DFO effect on thallium and DFO did not increase the effect of L1 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. Result of combined chelators treatment should be confirmed in a different experimental model before extrapolation to other systems.

  1. Effect of different chelated zinc sources on the growth and yield of maize (Zea mays L.

    Directory of Open Access Journals (Sweden)

    M. Tahir

    2009-05-01

    Full Text Available A field study was conducted at Agronomic Research Area, University of Agriculture, Faisalabad during spring, 2007 to evaluate the effect of different chelated zinc sources on growth and yield of maize (Zea mays L.. Crop was sown on well prepared soil in 1st week of March, 2007. The experiment was laid out according to randomized complete block design. The treatments comprised of different chelated zinc sources: ZnSO4-DTPA, ZnSO4-Fulvate, ZnSO4-Lignosulphonate, ZnSO4-EDTA and ZnSO4-H2O along with control (no zinc, repeated three times. Results showed that number of cobs plant-1, grain rows cob-1 and oil contents did not differ significantly. However, differences among treatments for plant height at harvest (cm, leaf area plant-1 (cm2, stem diameter (cm, cob length (cm, cob diameter (cm, 100-grains weight (g, number of grains cob-1, grains weight cob-1(g, biological yield (tons ha-1, grain yield (tons ha-1 and protein contents (% were significantly higher. Moreover, results also revealed that ZnSO4-DPTA was found the most effective Zn chelated source among all the treatments. Rest of the chelating agents were not too impressive as they showed varied response for different variables. The result of this experiment suggest further experimentation to explore behaviour of Zn-DTPA with other macro and micro nutrients and to calculate cost benefit ratio for use ofZn chelated compounds.

  2. Ligand Control of the Metal Coordination Sphere: Structures, Reactivity and Catalysis

    Directory of Open Access Journals (Sweden)

    Danopoulos Andreas A.

    2016-03-01

    Full Text Available Two major aspects of coordination/organometallic chemistry are discussed in this article: (i the use of functional chelating ligands to stabilize metal complexes while allowing easy stereodifferentiation within the coordination sphere and (ii the choice of suitable ligands to stabilize challenging ‘underligated’ metal complexes with electronically highly unsaturated metal centres, thus potentially displaying unusual reactivity. In both cases, the relevance to homogeneous catalysis will be discussed.

  3. 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

  4. TREATMENT OF WASTEWATER IN PLATING INDUSTRY BY CHELATE EXTRACTION METHOD

    Directory of Open Access Journals (Sweden)

    M. R. Massoudi Nejad, M. Rezazadeh Azary, M. Khatiby

    2007-01-01

    Full Text Available One of the most efficient methods to preserve environment is the procedure and method to achieve effective materials and the dual and reapplication of natural sources. In this research, After carrying out a vast study on the growing spot of Iranian oaks , of the 36 species and subspecies already identified, 10 species and subspecies were selected as they cover a vaster surface of Iranian woods in North Alborz Region, Arsabaran region and the western part of Zagros Mountains. 5 samples were collected of each type form diffrenet spots of the country. The effective and usable substances of oak fruit were extracted and isolated by the four methods of maceration, decoction, perculation and soxhlet tannin in one specie show no significant difference; However the amount of tannin in different species show significant differences in statistical term in such a way that the minimum and maximum tannin was found in Q.Brantii, Belangri with 9.7% tannin and Q.Macrantera, with 3.2 percent tannin. This amount was put in contact with wastewater various from plating industries in 20 to 50 mg/L amount. The mentioned wastewaters contained 50 to 750 mg/L heavy metals (chromium, nickel, zinc, copper and silver. The results were analyzed through a biofactor variance analysis model with repetition in each house (Toki Results showed that the removal output for zinc, copper, nickel and chromium without considering the initial concentration of the metal were 91 to 95 percent, 71 to 83.5 percent, 59 to 90 percent, and 84 to 85 percent, respectively. Also, with repect to the studies carried out with different methods and comparing the percentage of metals removal it was concluded that the removals output through applying 50 mg/L. hydroxide calcium along with 50 mg/L tannin with 82.3 percent average had the most effects in entire metals.

  5. Ruthenium complexes of chelating amido-functionalized N ...

    Indian Academy of Sciences (India)

    was removed under vacuum to yield the crude product as a brown solid. .... The crude product 3c was purified by column chromatography on a sil- ica gel by elution with a CHCl3/CH3OH (v/v 10:1) mixed medium to give the product 3c as brown solid. (0.208g .... bound in a η6-fashion to the metal center in these comp- lexes.

  6. EVALUATION OF THE CHELATING EFFECT OF METHANOLIC EXTRACT OF CORIANDRUM SATIVUM AND ITS FRACTIONS ON WISTAR RATS POISONED WITH LEAD ACETATE

    Science.gov (United States)

    Téllez-López, Miguel Ángel; Mora-Tovar, Gabriela; Ceniceros-Méndez, Iromi Marlen; García-Lujan, Concepción; Puente-Valenzuela, Cristo Omar; Vega-Menchaca, María del Carmen; Serrano-Gallardo, Luis Benjamín; Garza, Rubén García; Morán-Martínez, Javier

    2017-01-01

    Background: The rate of lead poisoning has decreased in recent years due to increased health control in industries that use this metal. However, it is still a public health problem worldwide. The use of various plants with chelating properties has been a topic of research today. In traditional medicine, it is said that Coriandrum sativum has chelating properties, but there is no scientific evidence to support this fact. The purpose of this research is to evaluate the chelating effect of methanol extract of coriander and its fractions on Wistar rats intoxicated with lead. Materials and Methods: In this research, male Wistar rats were poisoned with 50 mg/kg of lead acetate and treated with 50 mg/kg of methanol extract and its fractions. The extract and its fractions were administered to four treatment groups. Positive and negative controls were established. Hemoglobin, hematocrit and lead concentrations were analyzed; liver was evaluated histologically in control and treatment groups. Results: The methanol extract of coriander presented a LD50 >1000 mg/dL. The group administered with the methanol extract showed significant difference in the levels of hemoglobin and hematocrit compared to the negative control group. Lead concentration in treatment groups showed a decrease compared to the positive control. Histological evaluation of tissue showed less damage in groups administered with methanolic extract and its fractions compared to the positive control which presented structural alterations. Conclusion: Coriander extracts protect liver and lower lead concentration in rats intoxicated with lead in contrast to the positive control group. PMID:28573226

  7. Efficacy and safety of iron-chelation therapy with deferoxamine, deferiprone, and deferasirox for the treatment of iron-loaded patients with non-transfusion-dependent thalassemia syndromes

    Science.gov (United States)

    Kontoghiorghe, Christina N; Kontoghiorghes, George J

    2016-01-01

    The prevalence rate of thalassemia, which is endemic in Southeast Asia, the Middle East, and the Mediterranean, exceeds 100,000 live births per year. There are many genetic variants in thalassemia with different pathological severity, ranging from a mild and asymptomatic anemia to life-threatening clinical effects, requiring lifelong treatment, such as regular transfusions in thalassemia major (TM). Some of the thalassemias are non-transfusion-dependent, including many thalassemia intermedia (TI) variants, where iron overload is caused by chronic increase in iron absorption due to ineffective erythropoiesis. Many TI patients receive occasional transfusions. The rate of iron overloading in TI is much slower in comparison to TM patients. Iron toxicity in TI is usually manifested by the age of 30–40 years, and in TM by the age of 10 years. Subcutaneous deferoxamine (DFO), oral deferiprone (L1), and DFO–L1 combinations have been effectively used for more than 20 years for the treatment of iron overload in TM and TI patients, causing a significant reduction in morbidity and mortality. Selected protocols using DFO, L1, and their combination can be designed for personalized chelation therapy in TI, which can effectively and safely remove all the excess toxic iron and prevent cardiac, liver, and other organ damage. Both L1 and DF could also prevent iron absorption. The new oral chelator deferasirox (DFX) increases iron excretion and decreases liver iron in TM and TI. There are drawbacks in the use of DFX in TI, such as limitations related to dose, toxicity, and cost, iron load of the patients, and ineffective removal of excess iron from the heart. Furthermore, DFX appears to increase iron and other toxic metal absorption. Future treatments of TI and related iron-loading conditions could involve the use of the iron-chelating drugs and other drug combinations not only for increasing iron excretion but also for preventing iron absorption. PMID:26893541

  8. Effect of heavy metals on soil fungi

    Science.gov (United States)

    Sosak-Świderska, Bożena

    2010-05-01

    Fungi constitute a high proportion of the microbial biomass in soil.Being widespread in soil their large surface-to-volume ratio and high metabolic activity, fungi can contribute significantly to heavy metal dynamics in soil. At neutral pH heavy metals in soils tend to be immobilized to precipitation and/or absorption to cation exchange sites of clay minerals. In the acidic soils, metals are more mobile and enter food webs easier. Microbial production of acids and chelating agents can mobilize to toxic metals. Mobilization is often by uptake and intracellular accumulation of the heavy metlas, and in this way, the bioavailability of metals towards other organisms can be more reduced. Fungi were isolated from soils from Upper Silesia in Poland and belonged to widespread genera: Aspergillus, Cladosporium, Penicillium and Trichoderma. Fungi from different taxonomic groups differ greatly in their tolerance to heavy metals. This could be related to their wall structure and chemistry as well as biochemical and physiological characteristics of fungi. Localization of metals in fungal cells was studied using electron microscopy analysis. Metal biosorption in the cell wall can be complex as melanin granules. Fungal vacuoles have an important role in the regulation of the cytosolic concentration of metal ions, and may contribute to heavy metal tolerance.In polluted soils with heavy metals, fungal species composition can be changed and their physiological activity can be changed, too.

  9. Medicinal Radiopharmaceutical Chemistry of Metal Radiopharmaceuticals

    Science.gov (United States)

    Saw, Maung Maung

    2012-06-01

    Metal complexes have been used as medicinal compounds. Metals have advantageous features over organic compounds. Significant applications of metal complexes are in the field of nuclear medicine. Radiopharmaceuticals are drugs containing radioisotopes used for diagnostic and therapeutic purposes. The generalized targeting strategy for molecular imaging probe consists of three essential parts: (i) reporter unit or payload, (ii) carrier, and (iii) targeting system. Medicinal radiopharmaceutical chemistry pays special consideration to radioisotopes, as a reporter unit for diagnostic application or as a payload for therapeutic application. Targeting is achieved by a few approaches but the most common is the bifunctional chelator approach. While designing a radiopharmaceutical, a range of issues needs to be considered including properties of metal radioisotopes, bifunctional chelators, linkers, and targeting molecules. Designing radiopharmaceuticals requires consideration of two key words: "compounds of biological interest" and "fit for intended use." The ultimate goal is the development of new diagnostic methods and treatment. Diagnostic metal radiopharmaceuticals are used for SPECT and PET applications. Technetium chemistry constitutes a major portion of SPECT and gallium chemistry constitutes a major portion of PET. Therapeutic radiopharmaceuticals can be constructed by using alpha-, beta minus-, or Auger electron-emitting radiometals. Special uses of medicinal radiopharmaceuticals include internal radiation therapy, brachytherapy, immunoPET, radioimmunotherapy, and peptide receptor radionuclide imaging and therapy.

  10. Renal handling of amino acid /sup 99m/technetium chelates

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, M.; Banerjee, S.

    1988-09-01

    Four amino acids--alanine, 2,3-diaminopropionic acid, cystine, and cystein--and also one diamine, ethylenediamine, were chelated with /sup 99m/-technetium (/sup 99m/Tc), and their renal excretion patterns were studied in rabbits in the presence and absence of two renal tubular transport inhibitors, probenecid and 2,4-dinitrophenol. From the depression of renal excretion for the first three amino acid chelates, in the presence of the inhibitors, a renal tubular excretory pathway of elimination was suggested for these compounds. The renal excretions of /sup 99m/Tc-cystein and /sup 99m/Tc-ethylenediamine however, remained undepressed under similar experimental conditions. An explanation of these observations was forwarded from the possible chemical structures of these chelates.

  11. The determination of the rate of conjugation of immunoglobulin with a bifunctional chelator

    International Nuclear Information System (INIS)

    Malek, Z.; Miler, V.; Budsky, F.

    2006-01-01

    Imaging of cell's antigens with the use of labelled immunoglobulins allows imaging of specific receptors on cell membrane and specific tumours. It is necessary to carry out the labelling of the immunoglobulins with radionuclides of suitable physical properties which form cations (e.g., 111 In, 90 Y, 177 Lu) that form very strong chelates of sufficiently high stability constant preventing the dissociation of complexes or the radionuclide under 'in-vivo' conditions. The immunoglobulin must be conjugated with the bifunctional chelator (BCH), which contains both chelating unit and reactive group for binding to the immunoglobulin. In our laboratory we have conjugated human IgG and monoclonal antibody CD20 with diethylenetriamine pentaacetic acid dianhydride (cDTPAA). Radionuclides 90 Y and 177 Lu prepared on the LVR-15 reactor were used for labelling. After conjugation and labelling the yields in relation to the amount of isotopic carrier have been determined

  12. Dual action Smac mimetics-zinc chelators as pro-apoptotic antitumoral agents.

    Science.gov (United States)

    Manzoni, Leonardo; Gornati, Davide; Manzotti, Mattia; Cairati, Silvia; Bossi, Alberto; Arosio, Daniela; Lecis, Daniele; Seneci, Pierfausto

    2016-10-01

    Dual action compounds (DACs) based on 4-substituted aza-bicyclo[5.3.0]decane Smac mimetic scaffolds (ABDs) linked to a Zn(2+)-chelating moiety (DPA, o-hydroxy, m-allyl, N-acyl (E)-phenylhydrazone) through their 10 position are reported and characterized. Their synthesis, their target affinity (XIAP BIR3, Zn(2+)) in cell-free assays, their pro-apoptotic effects and cytotoxicity in tumor cells with varying sensitivity to Smac mimetics are described. The results are interpreted to evaluate the influence of Zn(2+) chelators on cell-free potency and on cellular permeability of DACs, and to propose novel avenues towards more potent antitumoral DACs based on Smac mimetics and Zn(2+) chelation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Antioxidant and mercury chelating activity of Psidium guajava var. pomifera L. leaves hydroalcoholic extract.

    Science.gov (United States)

    Pinho, Antonio Ivanildo; Oliveira, Cláudia Sirlene; Lovato, Fabricio Luís; Waczuk, Emily Pansera; Piccoli, Bruna Candia; Boligon, Aline Augusti; Leite, Nadghia Figueredo; Coutinho, Henrique Douglas Melo; Posser, Thais; Da Rocha, João Batista Teixeira; Franco, Jeferson Luis

    2017-01-01

    Mercury (Hg) is widely distributed in the environment and is known to produce several adverse effects in organisms. The aim of the present study was to examine the in vitro antioxidant activity and Hg chelating ability of the hydroalcoholic extract of Psidium guajava leaves (HEPG). In addition, the potential protective effects of HEPG against Hg(II) were evaluated using a yeast model (Saccharomyces cerevisiae). HEPG was found to exert significant antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl scavenger and inhibition of lipid peroxidation induced by Fe(II) assays in a concentration-dependent manner. The extract also exhibited significant Hg(II) chelating activity. In yeast, Hg(II) induced a significant decrease in cell viability. In contrast, HEPG partially prevented the fall in cell viability induced by Hg(II). In conclusion, HEPG exhibited protective effects against Hg(II)-mediated toxicity, which may be related to both antioxidant and Hg(II)-chelating activities.

  14. Silica nanoparticles as substrates for chelator-free labeling of oxophilic radioisotopes.

    Science.gov (United States)

    Shaffer, Travis M; Wall, Matthew A; Harmsen, Stefan; Longo, Valerie A; Drain, Charles Michael; Kircher, Moritz F; Grimm, Jan

    2015-02-11

    Chelator-free nanoparticles for intrinsic radiolabeling are highly desirable for whole-body imaging and therapeutic applications. Several reports have successfully demonstrated the principle of intrinsic radiolabeling. However, the work done to date has suffered from much of the same specificity issues as conventional molecular chelators, insofar as there is no singular nanoparticle substrate that has proven effective in binding a wide library of radiosotopes. Here we present amorphous silica nanoparticles as general substrates for chelator-free radiolabeling and demonstrate their ability to bind six medically relevant isotopes of various oxidation states with high radiochemical yield. We provide strong evidence that the stability of the binding correlates with the hardness of the radioisotope, corroborating the proposed operating principle. Intrinsically labeled silica nanoparticles prepared by this approach demonstrate excellent in vivo stability and efficacy in lymph node imaging.

  15. Determination of Chromium in Beef Heifers Nellore Supplemented with Chelate Chrome

    Directory of Open Access Journals (Sweden)

    P.S.A Moreira

    2013-11-01

    Full Text Available The objective of this work was to determine the amount of total chromium in beef heifers supplemented with chelated chromium in the rearing and finishing. We used 80 Nelore heifers at 12 months of age with mineral supplementation associated or not to chelate chromium, with average live weight of 220 kg. Were selected 36 heifer seach experimental group for analysis of meat samples. For the determination of chromium residue in the muscle tissue of the sample was1.5 g digested in a mixture of 5 ml 65% nitric acid and 1 ml of 30% hydrogen peroxide at 120° C for 12 hours block microdigestor. The total content of chromium was determined by spectrophotometry of atomic absorption flame. The experimental design was completely randomized and the results were analyzed by analysis of variance (ANOVA at 5% significance. It is concluded that the inclusion of chromium in the chelate heifers mineral supplementation increased the chromium content in the meat

  16. Modeling for Colloid and Chelator Facilitated Nuclide Transport in Radioactive Waste Disposal System

    International Nuclear Information System (INIS)

    Lee, Youn Myoung; Jeong, Jong Tae

    2010-08-01

    A modeling study and development of a total system performance assessment (TSPA) program template, by which assessment of safety and performance for a radioactive waste repository with normal and/or abnormal nuclide release cases can be made has been developed. Colloid and chelator facilitated transport that is believed to result for faster nuclide transport in various mediabothinthegeosphereandbiospherehas been evaluated deterministically and probabilistically to demonstrate the capability of the template developed through this study. To this end colloid and chelator facilitated nuclide transport has been modeled rather strainghtforwardly with assumed data through this study by utilizing some powerful function offered by GoldSim. An evaluation in view of apparent influence of colloid and chelator on the nuclide transport in the various media in and around a repository system with data assumed are illustrated

  17. Silica Nanoparticles as Substrates for Chelator-free Labeling of Oxophilic Radioisotopes

    Science.gov (United States)

    2016-01-01

    Chelator-free nanoparticles for intrinsic radiolabeling are highly desirable for whole-body imaging and therapeutic applications. Several reports have successfully demonstrated the principle of intrinsic radiolabeling. However, the work done to date has suffered from much of the same specificity issues as conventional molecular chelators, insofar as there is no singular nanoparticle substrate that has proven effective in binding a wide library of radiosotopes. Here we present amorphous silica nanoparticles as general substrates for chelator-free radiolabeling and demonstrate their ability to bind six medically relevant isotopes of various oxidation states with high radiochemical yield. We provide strong evidence that the stability of the binding correlates with the hardness of the radioisotope, corroborating the proposed operating principle. Intrinsically labeled silica nanoparticles prepared by this approach demonstrate excellent in vivo stability and efficacy in lymph node imaging. PMID:25559467

  18. 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.

  19. 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.

  20. Prooxidant and antioxidant properties of salicylaldehyde isonicotinoyl hydrazone iron chelators in HepG2 cells.

    Science.gov (United States)

    Caro, Andres A; Commissariat, Ava; Dunn, Caroline; Kim, Hyunjoo; García, Salvador Lorente; Smith, Allen; Strang, Harrison; Stuppy, Jake; Desrochers, Linda P; Goodwin, Thomas E

    2015-11-01

    Salicylaldehyde isonicotinoyl hydrazone (SIH) is an iron chelator of the aroylhydrazone class that displays antioxidant or prooxidant effects in different mammalian cell lines. Because the liver is the major site of iron storage, elucidating the effect of SIH on hepatic oxidative metabolism is critical for designing effective hepatic antioxidant therapies. Hepatocyte-like HepG2 cells were exposed to SIH or to analogs showing greater stability, such as N'-[1-(2-Hydroxyphenyl)ethyliden]isonicotinoyl hydrazide (HAPI), or devoid of iron chelating properties, such as benzaldehyde isonicotinoyl hydrazone (BIH), and toxicity, oxidative stress and antioxidant (glutathione) metabolism were evaluated. Autoxidation of Fe(2+)in vitro increased in the presence of SIH or HAPI (but not BIH), an effect partially blocked by Fe(2+) chelation. Incubation of HepG2 cells with SIH or HAPI (but not BIH) was non-toxic and increased reactive oxygen species (ROS) levels, activated the transcription factor Nrf2, induced the catalytic subunit of γ-glutamate cysteine ligase (Gclc), and increased glutathione concentration. Fe(2+) chelation decreased ROS and inhibited Nrf2 activation, and Nrf2 knock-down inhibited the induction of Gclc in the presence of HAPI. Inhibition of γ-glutamate cysteine ligase enzymatic activity inhibited the increase in glutathione caused by HAPI, and increased oxidative stress. SIH iron chelators display both prooxidant (increasing the autoxidation rate of Fe(2+)) and antioxidant (activating Nrf2 signaling) effects. Activation by SIH iron chelators of a hormetic antioxidant response contributes to their antioxidant properties and modulates the anti- and pro-oxidant balance. Copyright © 2015 Elsevier B.V. All rights reserved.