WorldWideScience

Sample records for tetraamine-derived bifunctional chelators

  1. 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

  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. 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.

  5. 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

  6. 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.

  7. Isothiocyanate-functionalized bifunctional chelates and fac-[MI(CO)3]+ (M = Re, 99mTc) complexes for targeting uPAR in prostate cancer

    Science.gov (United States)

    Developing strategies to rapidly incorporate the fac-[MI(CO)3]+ (M = Re, 99mTc) core into biological targeting vectors is a growing realm in radiopharmaceutical development. This work presents the preparation of a novel isothiocyanate-functionalized bifunctional chelate based on 2,2´-dipicolylamine ...

  8. Structure and potential applications of amido lanthanide complexes chelated by bifunctional b-diketiminate ligand

    Czech Academy of Sciences Publication Activity Database

    Olejník, R.; Padělková, Z.; Fridrichová, A.; Horáček, Michal; Merna, J.; Růžička, A.

    2014-01-01

    Roč. 759, JUN 2014 (2014), s. 1-10 ISSN 0022-328X R&D Projects: GA ČR GAP106/10/0924 Institutional support: RVO:61388955 Keywords : Bifunctional b-diketiminates * lanthanides * hydroamination Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.173, year: 2014

  9. Comparison of the octadentate bifunctional chelator DFO*-pPhe-NCS and the clinically used hexadentate bifunctional chelator DFO-pPhe-NCS for {sup 89}Zr-immuno-PET

    Energy Technology Data Exchange (ETDEWEB)

    Vugts, Danielle J.; Klaver, Chris; Sewing, Claudia; Poot, Alex J.; Adamzek, Kevin; Visser, Gerard W.M.; Dongen, Guus A.M.S. van [VU University Medical Center, Department of Radiology and Nuclear Medicine, Amsterdam (Netherlands); Huegli, Seraina; Mari, Cristina; Gasser, Gilles [University of Zurich, Department of Chemistry, Zurich (Switzerland); Valverde, Ibai E. [University of Basel Hospital, Division of Radiopharmaceutical Chemistry, Basel (Switzerland); Mindt, Thomas L. [Institute of Pharmaceutical Sciences, ETH Zurich, Zurich (Switzerland); General Hospital of Vienna, Ludwig Boltzmann Institute for Applied Diagnostics, Vienna (Austria)

    2017-02-15

    All clinical {sup 89}Zr-immuno-PET studies are currently performed with the chelator desferrioxamine (DFO). This chelator provides hexadentate coordination to zirconium, leaving two coordination sites available for coordination with, e.g., water molecules, which are relatively labile ligands. The unsaturated coordination of DFO to zirconium has been suggested to result in impaired stability of the complex in vivo and consequently in unwanted bone uptake of {sup 89}Zr. Aiming at clinical improvements, we report here on a bifunctional isothiocyanate variant of the octadentate chelator DFO* and the in vitro and in vivo comparison of its {sup 89}Zr-DFO*-mAb complex with {sup 89}Zr-DFO-mAb. The bifunctional chelator DFO*-pPhe-NCS was prepared from previously reported DFO* and p-phenylenediisothiocyanate. Subsequently, trastuzumab was conjugated with either DFO*-pPhe-NCS or commercial DFO-pPhe-NCS and radiolabeled with Zr-89 according to published procedures. In vitro stability experiments were carried out in saline, a histidine/sucrose buffer, and blood serum. The in vivo performance of the chelators was compared in N87 tumor-bearing mice by biodistribution studies and PET imaging. In 0.9 % NaCl {sup 89}Zr-DFO*-trastuzumab was more stable than {sup 89}Zr-DFO-trastuzumab; after 72 h incubation at 2-8 C 95 % and 58 % intact tracer were left, respectively, while in a histidine-sucrose buffer no difference was observed, both products were ≥ 92 % intact. In vivo uptake at 144 h post injection (p.i.) in tumors, blood, and most normal organs was similar for both conjugates, except for skin, liver, spleen, ileum, and bone. Tumor uptake was 32.59 ± 11.95 and 29.06 ± 8.66 % ID/g for {sup 89}Zr-DFO*-trastuzumab and {sup 89}Zr-DFO-trastuzumab, respectively. The bone uptake was significantly lower for {sup 89}Zr-DFO*-trastuzumab compared to {sup 89}Zr-DFO-trastuzumab. At 144 h p.i. for {sup 89}Zr-DFO*-trastuzumab and {sup 89}Zr-DFO-trastuzumab, the uptake in sternum was 0.92

  10. EVALUATION OF DESFERAL AS A BIFUNCTIONAL CHELATING AGENT FOR LABELING ANTIBODIES WITH ZR-89

    NARCIS (Netherlands)

    MEIJS, WE; HERSCHEID, JDM; Haisma, Hidde; PINEDO, HM

    1992-01-01

    Zirconium-desferal was prepared and analysed by TLC, NMR and u.v.-spectroscopy. The stoichiometry of the complex was found to be 1:1. Chelation of desferal, coupled to resin, with Zr-88 appeared to be fast and almost quantitative in various buffer systems in a broad pH-range (4-7). A high in vitro

  11. 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.

  12. 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

  13. Synthesis and evaluation of novel bifunctional chelating agents based on 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid for radiolabeling proteins

    International Nuclear Information System (INIS)

    Chappell, L.L.; Ma, D.; Milenic, D.E.; Garmestani, K.; Venditto, V.; Beitzel, M.P.; Brechbiel, M.W.

    2003-01-01

    Detailed synthesis of the bifunctional chelating agents 2-methyl-6-(p-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10 -tetraacetic acid (1B4M-DOTA) and 2-(p-isothiocyanatobenzyl)-5, 6-cyclohexano-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetate (CHX-DOTA) are reported. These chelating agents were compared to 2-(p-isothiocyanatobenzyl)-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (C-DOTA) and 1, 4, 7, 10-Tetraaza-N-(1-carboxy-3-(4-nitrophenyl)propyl)-N', N'', N'''-tris(acetic acid) cyclododecane (PA-DOTA) as their 177 Lu radiolabeled conjugates with Herceptin TM . In vitro stability of the immunoconjugates radiolabeled with 177 Lu was assessed by serum stability studies. The in vivo stability of the radiolabeled immunoconjugates and their targeting characteristics were determined by biodistribution studies in LS-174T xenograft tumor-bearing mice. Relative radiolabeling rates and efficiencies were determined for all four immunoconjugates. Insertion of the 1B4M moiety into the DOTA backbone increases radiometal chelation rate and provides complex stability comparable to C-DOTA and PA-DOTA while the CHX-DOTA appears to not form as stable a 177 Lu complex while exhibiting a substantial increase in formation rate. The 1B4M-DOTAmay have potential for radioimmunotherapy applications. Published by Elsevier Inc. All rights reserved

  14. A systematic study on the utility of CHX-A''-DTPA-NCS and NOTA-NCS as bifunctional chelators for177Lu radiopharmaceuticals.

    Science.gov (United States)

    Pandey, Usha; Gamre, Naresh; Lohar, Sharad Pandurang; Dash, Ashutosh

    2017-09-01

    This paper describes the evaluation of [(R)-2-Amino-3-(4-isothiocyanatophenyl)propyl]-trans-(S,S)-cyclohexane-1,2-diamine-pentaacetic acid (CHX-A''-DTPA-NCS) and 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA-NCS) as bifunctional chelators for 177 Lu. While 177 Lu-CHX-A''-DTPA-NCS could be obtained in high yields at equimolar ratios of lutetium to CHX-A''-DTPA-NCS, >95% yield of 177 Lu-NOTA-NCS could be achieved at 1:2M ratio of lutetium to NOTA-NCS. Trace metals reduced the yields of 177 Lu-NOTA-NCS significantly as compared to 177 Lu-CHX-A''-DTPA-NCS. In vitro stability of 177 Lu-CHX-A''-DTPA-NCS was also superior to 177 Lu-NOTA-NCS. It could be concluded from this study that among the two chelators evaluated, CHX-A''-DTPA-NCS is more appropriate for preparation of 177 Lu radiopharmaceuticals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Deferasirox-TAT(47-57) peptide conjugate as a water soluble, bifunctional iron chelator with potential use in neuromedicine.

    Science.gov (United States)

    Goswami, Dibakar; Vitorino, Hector A; Alta, Roxana Y P; Silvestre, Daniel M; Nomura, Cassiana S; Machini, M Teresa; Espósito, Breno P

    2015-10-01

    Deferasirox (DFX), an orally active and clinically approved iron chelator, is being used extensively for the treatment of iron overload. However, its water insolubility makes it cumbersome for practical use. In addition to this, the low efficacy of DFX to remove brain iron prompted us to synthesize and evaluate a DFX-TAT(47-57) peptide conjugate for its iron chelation properties and permeability across RBE4 cell line, an in vitro model of the blood-brain barrier. The water-soluble conjugate was able to remove labile iron from buffered solution as well as from iron overloaded sera, and the permeability of DFX-TAT(47-57) conjugate into RBE4 cells was not affected compared to parent deferasirox. The iron bound conjugate was also able to translocate through the cell membrane.

  16. Synthesis and functionalization of bifunctional chelates for 64Cu complexation for their applications by positron emission tomography (PET) imaging and radiotherapy

    International Nuclear Information System (INIS)

    Roux, Amandine

    2014-01-01

    This work aimed to develop a new family of bis-pidine-type ligands for copper(II) complexation with applications in Positron Emission Tomography (PET). Indeed, copper 64 is a radioelement whose study in PET imaging is booming. Bis-pidines have the benefit of having a rigid and pre-organized structure for complexation of a large number of transition metals. In this work we present the synthesis and optimization of new ligands whose structural and physico-chemical properties have been studied. One ligand showed very good results because it possesses all of kinetic and thermodynamic parameters which are necessary for its application to PET imaging. Different strategies of functionalization have been studied to obtain bifunctional chelates. A lysine derivative has been coupled to a maleimide function (regio-selective of cysteines), to abiotine (which displays a strong affinity for streptavidin) or to a Bodipy pattern for obtaining a bimodal probe (UV-visible and PET). Finally, we present an extension of this bis-pidine family by increasing the number of coordination functions or by synthesizing tricyclic compounds to modulate the selectivity of these molecules. (author)

  17. Facile labelling of an anti-epidermal growth factor receptor nanobody with 68Ga via a novel bifunctional desferal chelate for immuno-PET

    International Nuclear Information System (INIS)

    Vosjan, Maria J.W.D.; Perk, Lars R.; Stigter van Walsum, Marijke; Roovers, Rob C.; Bergen en Henegouwen, Paul M.P. van; Visser, Gerard W.M.; Dongen, Guus A.M.S. van

    2011-01-01

    The ∝15 kDa variable domains of camelid heavy-chain-only antibodies (called Nanobodies registered ) have the flexibility to be formatted as monovalent, monospecific, multivalent or multispecific single chain proteins with either fast or slow pharmacokinetics. We report the evaluation of the fast kinetic anti-epidermal growth factor receptor (EGFR) Nanobody 7D12, labelled with 68 Ga via the novel bifunctional chelate (BFC) p-isothiocyanatobenzyl-desferrioxamine (Df-Bz-NCS). Df-Bz-NCS has recently been introduced as the chelate of choice for 89 Zr immuno-positron emission tomography (PET). Nanobody 7D12 was premodified with Df-Bz-NCS at pH 9. Radiolabelling with purified 68 Ga was performed at pH 5.0-6.5 for 5 min at room temperature. For in vitro stability measurements in storage buffer (0.25 M NaOAc with 5 mg ml -1 gentisic acid, pH 5.5) at 4 C or in human serum at 37 C, a mixture of 67 Ga and 68 Ga was used. Biodistribution and immuno-PET studies of 68 Ga-Df-Bz-NCS-7D12 were performed in nude mice bearing A431 xenografts using 89 Zr-Df-Bz-NCS-7D12 as the reference conjugate. The Df-Bz-NCS chelate was conjugated to Nanobody 7D12 with a chelate to Nanobody molar substitution ratio of 0.2:1. The overall 68 Ga radiochemical yield was 55-70% (not corrected for decay); specific activity was 100-500 MBq/mg. Radiochemical purity of the conjugate was >96%, while the integrity and immunoreactivity were preserved. 68/67 Ga-Df-Bz-NCS-7D12 was stable in storage buffer as well as in human serum during a 5-h incubation period ( 68 Ga-labelled Nanobody 7D12 showed high uptake in A431 tumours (ranging from 6.1 ± 1.3 to 7.2 ± 1.5%ID/g at 1-3 h after injection) and high tumour to blood ratios, which increased from 8.2 to 14.4 and 25.7 at 1, 2 and 3 h after injection, respectively. High uptake was also observed in the kidneys. Biodistribution was similar to that of the reference conjugate 89 Zr-Df-Bz-NCS-7D12. Tumours were clearly visualized in a PET imaging study. Via a rapid

  18. Facile labelling of an anti-epidermal growth factor receptor Nanobody with 68Ga via a novel bifunctional desferal chelate for immuno-PET.

    Science.gov (United States)

    Vosjan, Maria J W D; Perk, Lars R; Roovers, Rob C; Visser, Gerard W M; Stigter-van Walsum, Marijke; van Bergen En Henegouwen, Paul M P; van Dongen, Guus A M S

    2011-04-01

    The ∼15 kDa variable domains of camelid heavy-chain-only antibodies (called Nanobodies®) have the flexibility to be formatted as monovalent, monospecific, multivalent or multispecific single chain proteins with either fast or slow pharmacokinetics. We report the evaluation of the fast kinetic anti-epidermal growth factor receptor (EGFR) Nanobody 7D12, labelled with (68)Ga via the novel bifunctional chelate (BFC) p-isothiocyanatobenzyl-desferrioxamine (Df-Bz-NCS). Df-Bz-NCS has recently been introduced as the chelate of choice for (89)Zr immuno-positron emission tomography (PET). Nanobody 7D12 was premodified with Df-Bz-NCS at pH 9. Radiolabelling with purified (68)Ga was performed at pH 5.0-6.5 for 5 min at room temperature. For in vitro stability measurements in storage buffer (0.25 M NaOAc with 5 mg ml(-1) gentisic acid, pH 5.5) at 4°C or in human serum at 37°C, a mixture of (67)Ga and (68)Ga was used. Biodistribution and immuno-PET studies of (68)Ga-Df-Bz-NCS-7D12 were performed in nude mice bearing A431 xenografts using (89)Zr-Df-Bz-NCS-7D12 as the reference conjugate. The Df-Bz-NCS chelate was conjugated to Nanobody 7D12 with a chelate to Nanobody molar substitution ratio of 0.2:1. The overall (68)Ga radiochemical yield was 55-70% (not corrected for decay); specific activity was 100-500 MBq/mg. Radiochemical purity of the conjugate was >96%, while the integrity and immunoreactivity were preserved. (68/67)Ga-Df-Bz-NCS-7D12 was stable in storage buffer as well as in human serum during a 5-h incubation period (Nanobody 7D12 showed high uptake in A431 tumours (ranging from 6.1 ± 1.3 to 7.2 ± 1.5%ID/g at 1-3 h after injection) and high tumour to blood ratios, which increased from 8.2 to 14.4 and 25.7 at 1, 2 and 3 h after injection, respectively. High uptake was also observed in the kidneys. Biodistribution was similar to that of the reference conjugate (89)Zr-Df-Bz-NCS-7D12. Tumours were clearly visualized in a PET imaging study. Via a rapid

  19. Facile labelling of an anti-epidermal growth factor receptor nanobody with {sup 68}Ga via a novel bifunctional desferal chelate for immuno-PET

    Energy Technology Data Exchange (ETDEWEB)

    Vosjan, Maria J.W.D.; Perk, Lars R.; Stigter van Walsum, Marijke [VU University Medical Center, Department of Otolaryngology/Head and Neck Surgery, De Boelelaan 1117, P.O. Box 7057, Amsterdam (Netherlands); Roovers, Rob C.; Bergen en Henegouwen, Paul M.P. van [Utrecht University, Cellular Dynamics, Science Faculty, Utrecht (Netherlands); Visser, Gerard W.M. [VU University Medical Center, Department of Nuclear Medicine and PET Research, Amsterdam (Netherlands); Dongen, Guus A.M.S. van [VU University Medical Center, Department of Otolaryngology/Head and Neck Surgery, De Boelelaan 1117, P.O. Box 7057, Amsterdam (Netherlands); VU University Medical Center, Department of Nuclear Medicine and PET Research, Amsterdam (Netherlands)

    2011-04-15

    The {proportional_to}15 kDa variable domains of camelid heavy-chain-only antibodies (called Nanobodies {sup registered}) have the flexibility to be formatted as monovalent, monospecific, multivalent or multispecific single chain proteins with either fast or slow pharmacokinetics. We report the evaluation of the fast kinetic anti-epidermal growth factor receptor (EGFR) Nanobody 7D12, labelled with {sup 68}Ga via the novel bifunctional chelate (BFC) p-isothiocyanatobenzyl-desferrioxamine (Df-Bz-NCS). Df-Bz-NCS has recently been introduced as the chelate of choice for {sup 89}Zr immuno-positron emission tomography (PET). Nanobody 7D12 was premodified with Df-Bz-NCS at pH 9. Radiolabelling with purified {sup 68}Ga was performed at pH 5.0-6.5 for 5 min at room temperature. For in vitro stability measurements in storage buffer (0.25 M NaOAc with 5 mg ml{sup -1} gentisic acid, pH 5.5) at 4 C or in human serum at 37 C, a mixture of {sup 67}Ga and {sup 68}Ga was used. Biodistribution and immuno-PET studies of {sup 68}Ga-Df-Bz-NCS-7D12 were performed in nude mice bearing A431 xenografts using {sup 89}Zr-Df-Bz-NCS-7D12 as the reference conjugate. The Df-Bz-NCS chelate was conjugated to Nanobody 7D12 with a chelate to Nanobody molar substitution ratio of 0.2:1. The overall {sup 68}Ga radiochemical yield was 55-70% (not corrected for decay); specific activity was 100-500 MBq/mg. Radiochemical purity of the conjugate was >96%, while the integrity and immunoreactivity were preserved. {sup 68/67}Ga-Df-Bz-NCS-7D12 was stable in storage buffer as well as in human serum during a 5-h incubation period (<2% radioactivity loss). In biodistribution studies the {sup 68}Ga-labelled Nanobody 7D12 showed high uptake in A431 tumours (ranging from 6.1 {+-} 1.3 to 7.2 {+-} 1.5%ID/g at 1-3 h after injection) and high tumour to blood ratios, which increased from 8.2 to 14.4 and 25.7 at 1, 2 and 3 h after injection, respectively. High uptake was also observed in the kidneys. Biodistribution was

  20. Isothiocyanate-Functionalized Bifunctional Chelates and fac-[M(I)(CO)3](+) (M = Re, (99m)Tc) Complexes for Targeting uPAR in Prostate Cancer.

    Science.gov (United States)

    Kasten, Benjamin B; Ma, Xiaowei; Cheng, Kai; Bu, Lihong; Slocumb, Winston S; Hayes, Thomas R; Trabue, Steven; Cheng, Zhen; Benny, Paul D

    2016-01-20

    Developing new strategies to rapidly incorporate the fac-[M(I)(CO)3](+) (M = Re, (99m)Tc) core into biological targeting vectors in radiopharmaceuticals continues to expand as molecules become more complex and as efforts to minimize nonspecific binding increase. This work examines a novel isothiocyanate-functionalized bifunctional chelate based on 2,2'-dipicolylamine (DPA) specifically designed for complexing the fac-[M(I)(CO)3](+) core. Two strategies (postlabeling and prelabeling) were explored using the isothiocyanate-functionalized DPA to determine the effectiveness of assembly on the overall yield and purity of the complex with amine containing biomolecules. A model amino acid (lysine) examined (1) amine conjugation of isothiocyanate-functionalized DPA followed by complexation with fac-[M(I)(CO)3](+) (postlabeling) and (2) complexation of fac-[M(I)(CO)3](+) with isothiocyanate-functionalized DPA followed by amine conjugation (prelabeling). Conducted with stable Re and radioactive (99m)Tc analogs, both strategies formed the product in good to excellent yields under macroscopic and radiotracer concentrations. A synthetic peptide (AE105) which targets an emerging biomarker in CaP prognosis, urokinase-type plasminogen activator receptor (uPAR), was also explored using the isothiocyanate-functionalized DPA strategy. In vitro PC-3 (uPAR+) cell uptake assays with the (99m)Tc-labeled peptide (8a) showed 4.2 ± 0.5% uptake at 4 h. In a murine model bearing PC-3 tumor xenografts, in vivo biodistribution of 8a led to favorable tumor uptake (3.7 ± 0.7% ID/g) at 4 h p.i. with relatively low accumulation (fac-[M(I)(CO)3](+).

  1. A new bifunctional chelating agent conjugated with monoclonal antibody and labelled with technetium-99m for targeted scintigraphy: 6-(4-isothiocyanatobenzyl)-5,7-dioxo-1,11-(carboxymethyl)-1,4,8,11-tetraazacyclotridecane.

    Science.gov (United States)

    Mishra, Anil Kumar; Panwar, Puja; Hosono, Makoto; Chuttani, Krishna; Mishra, Pushpa; Sharma, Rakesh Kumar; Chatal, Jean-Francois

    2004-01-01

    The purpose of this study was to obtain the convenient, synthetically useful bifunctional chelating agent, 6-(4-isothiocyanatobenzyl)-5,7-dioxo-1,11-(carboxymethyl)-1,4,8,11-tetraazacyclotridecane, and to apply it to stable (99m)Tc-labelling of monoclonal antibodies (mAbs). The chelate was synthesised by reaction of nitrobenzyl malonate and triethylenetetramine followed by alkylation by reacting with bromoacetic acid at pH 10. The amino group was converted to isothiocyanato derivative by reacting with thiophosgene at pH 2.0. Conjugation with mAbs [(anti-carcinoembryonic antigen (CEA) and anti-epidermal growth factor receptor (EGFr)] was performed at pH 8.4 using trisodium phosphate solution by incubating at 37 degrees C for 1 h and subjected to purification on size exclusion chromatography. When radioimmunoconjugates were labelled with (99m)Tc, the specific activity of immunoconjugates was 20-30 mCi/mg of protein and their immunoreactivity exceeded 80%. The stability in serum indicated that the metal remained bound to antibodies. Biodistribution studies in athymic mice grafted with U-87 human glioblastoma multiforme and MDA-MB-468 human breast carcinoma tumours revealed significant localisation of (99m)Tc-labelled antibodies in tumours and reduced accumulation in normal organs. This bifunctional chelating agent is promising for immunoscintigraphy because of good tumour-to-normal organ contrast.

  2. Nature of the bifunctional chelating agent used for radioimmunotherapy with yttrium-88 monoclonal antibodies: critical factors in determining in vivo survival and organ toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Kozak, R.W.; Raubitschek, A.; Mirzadeh, S.; Brechbiel, M.W.; Junghaus, R.; Gansow, O.A.; Waldmann, T.A. (Center for Biologics Evaluation and Research, FDA, Bethesda, MD (USA))

    1989-05-15

    One factor that is critical to the potential effectiveness of radioimmunotherapy is the design of radiometal-chelated antibodies that will be stable in vivo. Stability in vivo depends on the condition that both the chelate linkage and radiolabeling procedures not alter antibody specificity and biodistribution. In addition, synthesis and selection of the chelating agent is critical for each radiometal in order to prevent inappropriate release of the radiometal in vivo. In the present study, we compare the in vivo stability of seven radioimmunoconjugates that use different polyaminocarboxylate chelating agents to complex yttrium-88 to the mouse anti-human interleukin-2 receptor monoclonal antibody, anti-Tac. Chelate linkage and radiolabeling procedures did not alter the immunospecificity of anti-Tac. In order to assess whether yttrium was inappropriately released from the chelate-coupled antibody in vivo, iodine-131-labeled and yttrium-88 chelate-coupled antibodies were simultaneously administered to the same animals to correlate the decline in yttrium and radioiodinated antibody activity. The four stable yttrium-88 chelate-coupled antibodies studied displayed similar iodine-131 and yttrium-88 activity, indicating minimal elution of yttrium-88 from the complex. In contrast, the unstable yttrium-88 chelate-coupled antibodies had serum yttrium-88 activities that declined much more rapidly than their iodine-131 activities, suggesting loss of the radiolabel yttrium-88 from the chelate. Furthermore, high rates of yttrium-88 elution correlated with deposition in bone. Four chelating agents emerged as promising immunotherapeutic reagents: isothiocyanate benzyl DTPA and its derivatives 1B3M, MX, and 1M3B.

  3. Simple, mild, one-step labelling of proteins with gallium-68 using a tris(hydroxypyridinone) bifunctional chelator: a 68Ga-THP-scFv targeting the prostate-specific membrane antigen.

    Science.gov (United States)

    Nawaz, Saima; Mullen, Gregory E D; Sunassee, Kavitha; Bordoloi, Jayanta; Blower, Philip J; Ballinger, James R

    2017-10-25

    Labelling proteins with gallium-68 using bifunctional chelators is often problematic because of unsuitably harsh labelling conditions such as low pH or high temperature and may entail post-labelling purification. To determine whether tris(hydroxypyridinone) (THP) bifunctional chelators offer a potential solution to this problem, we have evaluated the labelling and biodistribution of a THP conjugate with a new single-chain antibody against the prostate-specific membrane antigen (PSMA), an attractive target for staging prostate cancer (PCa). A single-chain variable fragment (scFv) of J591, a monoclonal antibody that recognises an external epitope of PSMA, was prepared in order to achieve biokinetics matched to the half-life of gallium-68. The scFv, J591c-scFv, was engineered with a C-terminal cysteine. J591c-scFv was produced in HEK293T cells and purified by size-exclusion chromatography. A maleimide THP derivative (THP-mal) was coupled site-specifically to the C-terminal cysteine residue. The THP-mal-J591c-scFv conjugate was labelled with ammonium acetate-buffered gallium-68 from a 68 Ge/ 68 Ga generator at room temperature and neutral pH. The labelled conjugate was evaluated in the PCa cell line DU145 and its PSMA-overexpressing variant in vitro and xenografted in SCID mice. J591c-scFv was produced in yields of 4-6 mg/l culture supernatant and efficiently coupled with the THP-mal bifunctional chelator. Labelling yields > 95% were achieved at room temperature following incubation of 5 μg conjugate with gallium-68 for 5 min without post-labelling purification. 68 Ga-THP-mal-J591c-scFv was stable in serum and showed selective binding to the DU145-PSMA cell line, allowing an IC50 value of 31.5 nM to be determined for unmodified J591c-scFv. Serial PET/CT imaging showed rapid, specific tumour uptake and clearance via renal elimination. Accumulation in DU145-PSMA xenografts at 90 min post-injection was 5.4 ± 0.5%ID/g compared with 0.5 ± 0.2%ID/g in DU145

  4. Synthesis of macrocyclic bifunctional chelating agents: 1,4,7 - tri(carboxy-methyl) - 10 - (2-amino-ethyl) - 1,4,7,10 - tetra-aza-cyclo-dodecane and 1,4,8 - tri(carboxy-methyl)- 11 - (2-amino-ethyl) - 1,4,8,11 - tetra-aza-cyclo-tetra-decane

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, A.K. [Institute of Nuclear Medicine and Allied Sciences, Dept. of Radiopharmaceuticals, Delhi (India); Chatal, J.F. [Institut National de la Sante et de la Recherche Medicale (INSERM U-463), Lab. d' Interactions Recepteurs Ligands en Immunocancerologie et immunopathologie, 44 - Nantes (France)

    2001-02-01

    The convenient, synthetically useful bifunctional chelating agents, 1,4,7 - tri(carboxy-methyl) - 10 - (2-amino-ethyl) - 1,4,7,10 - tetra-aza-cyclo-dodecane and 1,4,8 - tri(carboxy-methyl) - 11 - (2-amino-ethyl) - 1,4,8,11 - tetra-aza-cyclo-tetra-decane, were obtained by reaction of ethyl bromo-acetate with 1,4,7,10 - tetra-aza-cyclo-dodecane and 1,4,8,11 - tetra-aza-cyclo-tetra-decane, followed by reaction with N-(2-bromo-ethyl)phthalimide. This method is proven to be more efficient to prepare bifunctional chelating agents with aliphatic side arms in high yields, above 53%. (authors)

  5. Synthesis of macrocyclic bifunctional chelating agents: 1,4,7 - tri(carboxy-methyl) - 10 - (2-amino-ethyl) - 1,4,7,10 - tetra-aza-cyclo-dodecane and 1,4,8 - tri(carboxy-methyl)- 11 - (2-amino-ethyl) - 1,4,8,11 - tetra-aza-cyclo-tetra-decane

    International Nuclear Information System (INIS)

    Mishra, A.K.; Chatal, J.F.

    2001-01-01

    The convenient, synthetically useful bifunctional chelating agents, 1,4,7 - tri(carboxy-methyl) - 10 - (2-amino-ethyl) - 1,4,7,10 - tetra-aza-cyclo-dodecane and 1,4,8 - tri(carboxy-methyl) - 11 - (2-amino-ethyl) - 1,4,8,11 - tetra-aza-cyclo-tetra-decane, were obtained by reaction of ethyl bromo-acetate with 1,4,7,10 - tetra-aza-cyclo-dodecane and 1,4,8,11 - tetra-aza-cyclo-tetra-decane, followed by reaction with N-(2-bromo-ethyl)phthalimide. This method is proven to be more efficient to prepare bifunctional chelating agents with aliphatic side arms in high yields, above 53%. (authors)

  6. Clinical evaluation of two new bifunctional chelating agents for immunoscintigraphy (I.S.) with indium-111-anti-CEA monoclonal antibody

    Energy Technology Data Exchange (ETDEWEB)

    Chatal, J.F.; Gestin, J.F.; Faivre-Chauvet, A. [Brookhaven National Lab., Upton, NY (United States)] [and others

    1994-05-01

    Previous animal studies have shown that chelates of In-111 with semi-rigid cyclohexyl EDTA (CDTA) derivatives produce improved in-vivo stability compared to non-rigid analogs. Two CDTA derivatives, CDTA-EN-SCN (dilithium salt of N-(methyl (2-isothiocyanato-ethyl) carbamide) trans-1,2-diaminocyclohexane N,N{prime},N{prime}-triacetic acid) and 4-ICE (4-isothiocyanato-trans-1,2-diaminocyclohexane-N,N,N {prime},N{prime}-tetraacetic acid), were synthesized, coupled to anti-CEA F(ab{prime}){sub 2} fragments and labeled with In-111 with a specific activity of 111MBq/mg. Five patients were injected with CDTA-EN-SCN and 4 with 4-ICE. IS was performed 3 days after injection. Mean blood activity, at the time of IS, expressed as the percentage of injected dose per ml, was 0.0038% with 4-ICE and 0.0071% with CDTA-EN-SCN. For comparative purposes, the mean value previously obtained with DTPA coupled to the same antibody was 0.0035%. Liver uptake was estimated from semi-quantitative calculations on scintigraphic images. Compared with the value obtained in a patient injected with 72.3 antibody coupled to DTFPA, a 2.5-fold reduction in liver uptake was observed. However, this reduction was sufficient to allow visualization of a large liver metastasis in one patient. With CDTA-EN-SCN, colon activity was moderate in 3 patients and intense in 1. With 4-ICE it was moderate in 2 patients and intense in 1, With CDTA-EN-SCN, true-positive IS results were observed in 2 patients (pelvis and mediastinum) and a false-negative result was observed in 1 patient (pelvis). In 3 patients, IS was negative and recurrence not yet confirmed despite high serum CEA level. With 4-FICE, true-positive IS results were observed in 3 patients (2 pelvis, 1 lung). A false-negative result was found in a patient with a confirmed liver metastasis.

  7. 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 ...

  8. Bifunctional antibodies for radioimmunotherapy.

    Science.gov (United States)

    Chatal, J F; Faivre-Chauvet, A; Bardies, M; Peltier, P; Gautherot, E; Barbet, J

    1995-04-01

    In two-step targeting technique using bifunctional antibodies, a nonradiolabeled immunoconjugate with slow uptake kinetics (several days) is initially injected, followed by a small radiolabeled hapten with fast kinetics (several hours) that binds to the bispecific immunoconjugate already taken up by the tumor target. In patients with colorectal or medullary thyroid cancer, clinical studies performed with an anti-CEA/anti-DTPA-indium bifunctional antibody and an indium-111-labeled di-DTPA-TL bivalent hapten showed that tumor uptake was not modified compared to results for F(ab')2 fragments of the same anti-CEA antibody directly labeled with indium-111, whereas the radioactivity of normal tissues was significantly reduced (3- to 6-fold). The fast tumor uptake kinetics (several hours) and high or very high tumor-to-normal tissue ratios obtained with the bifunctional antibody technique are favorable parameters for efficient radioimmunotherapy.

  9. 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

  10. 67Ga(NODASA): a new potential bifunctional radioligand for coupling to peptides

    International Nuclear Information System (INIS)

    Andre, J.P.; Maecke, H.R.; Zehnder, M.; Macko, L.; Kaspar, A.

    1998-01-01

    A new bifunctional chelator NODASA (1,4,7-triazacyclononane-1-succinic acid-4,7-diacetic acid) has been synthesised and its Ga(III) complex was crystallographically characterized by X-ray diffraction. The complex showed to be stable in serum and in acidic conditions and its stability constant was determined using a competition method with an auxiliary ligand. The conjugation of Ga(NODASA) to a model aminoacidamide proved the feasibility of a prelabelling approach. (author)

  11. 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.

  12. 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.

  13. 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...

  14. Combining conformational sampling and selection to identify the binding mode of zinc-bound amyloid peptides with bifunctional molecules

    Science.gov (United States)

    Xu, Liang; Gao, Ke; Bao, Chunyu; Wang, Xicheng

    2012-08-01

    The pathogenesis of Alzheimer's disease (AD) has been suggested to be related with the aggregation of amyloid β (Aβ) peptides. Metal ions (e.g. Cu, Fe, and Zn) are supposed to induce the aggregation of Aβ. Recent development of bifunctional molecules that are capable of interacting with Aβ and chelating biometal ions provides promising therapeutics to AD. However, the molecular mechanism for how Aβ, metal ions, and bifunctional molecules interact with each other is still elusive. In this study, the binding mode of Zn2+-bound Aβ with bifunctional molecules was investigated by the combination of conformational sampling of full-length Aβ peptides using replica exchange molecular dynamics simulations (REMD) and conformational selection using molecular docking and classical MD simulations. We demonstrate that Zn2+-bound Aβ(1-40) and Aβ(1-42) exhibit different conformational ensemble. Both Aβ peptides can adopt various conformations to recognize typical bifunctional molecules with different binding affinities. The bifunctional molecules exhibit their dual functions by first preferentially interfering with hydrophobic residues 17-21 and/or 30-35 of Zn2+-bound Aβ. Additional interactions with residues surrounding Zn2+ could possibly disrupt interactions between Zn2+ and Aβ, which then facilitate these small molecules to chelate Zn2+. The binding free energy calculations further demonstrate that the association of Aβ with bifunctional molecules is driven by enthalpy. Our results provide a feasible approach to understand the recognition mechanism of disordered proteins with small molecules, which could be helpful to the design of novel AD drugs.

  15. 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

  16. 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.

  17. 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.

  18. 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 ...

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Recent Development of Bifunctional Small Molecules to Study Metal-Amyloid-β Species in Alzheimer's Disease

    Directory of Open Access Journals (Sweden)

    Joseph J. Braymer

    2011-01-01

    Full Text Available Alzheimer's disease (AD is a multifactorial neurodegenerative disease related to the deposition of aggregated amyloid-β (Aβ peptides in the brain. It has been proposed that metal ion dyshomeostasis and miscompartmentalization contribute to AD progression, especially as metal ions (e.g., Cu(II and Zn(II found in Aβ plaques of the diseased brain can bind to Aβ and be linked to aggregation and neurotoxicity. The role of metal ions in AD pathogenesis, however, is uncertain. To accelerate understanding in this area and contribute to therapeutic development, recent efforts to devise suitable chemical reagents that can target metal ions associated with Aβ have been made using rational structure-based design that combines two functions (metal chelation and Aβ interaction in the same molecule. This paper presents bifunctional compounds developed by two different design strategies (linkage or incorporation and discusses progress in their applications as chemical tools and/or potential therapeutics.

  4. Identifying and annotating human bifunctional RNAs reveals their versatile functions.

    Science.gov (United States)

    Chen, Geng; Yang, Juan; Chen, Jiwei; Song, Yunjie; Cao, Ruifang; Shi, Tieliu; Shi, Leming

    2016-10-01

    Bifunctional RNAs that possess both protein-coding and noncoding functional properties were less explored and poorly understood. Here we systematically explored the characteristics and functions of such human bifunctional RNAs by integrating tandem mass spectrometry and RNA-seq data. We first constructed a pipeline to identify and annotate bifunctional RNAs, leading to the characterization of 132 high-confidence bifunctional RNAs. Our analyses indicate that bifunctional RNAs may be involved in human embryonic development and can be functional in diverse tissues. Moreover, bifunctional RNAs could interact with multiple miRNAs and RNA-binding proteins to exert their corresponding roles. Bifunctional RNAs may also function as competing endogenous RNAs to regulate the expression of many genes by competing for common targeting miRNAs. Finally, somatic mutations of diverse carcinomas may generate harmful effect on corresponding bifunctional RNAs. Collectively, our study not only provides the pipeline for identifying and annotating bifunctional RNAs but also reveals their important gene-regulatory functions.

  5. Fat & fabulous: bifunctional lipids in the spotlight.

    Science.gov (United States)

    Haberkant, Per; Holthuis, Joost C M

    2014-08-01

    Understanding biological processes at the mechanistic level requires a systematic charting of the physical and functional links between all cellular components. While protein-protein and protein-nucleic acid networks have been subject to many global surveys, other critical cellular components such as membrane lipids have rarely been studied in large-scale interaction screens. Here, we review the development of photoactivatable and clickable lipid analogues-so-called bifunctional lipids-as novel chemical tools that enable a global profiling of lipid-protein interactions in biological membranes. Recent studies indicate that bifunctional lipids hold great promise in systematic efforts to dissect the elaborate crosstalk between proteins and lipids in live cells and organisms. This article is part of a Special Issue entitled Tools to study lipid functions. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. 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

  7. 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.

  8. 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...

  9. 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.

  10. Bifunctional electrocatalyst for oxygen/air electrodes

    International Nuclear Information System (INIS)

    Sasikala, N.; Ramya, K.; Dhathathreyan, K.S.

    2014-01-01

    Highlights: • Nano-Silver powder was prepared by chemical method. • Ag catalyst was characterized by SEM and XRD studies. • Ag was investigated as bi-functional electrocatalyst for oxygen/air electrodes. • Ag shows good electrochemical activity towards OER and ORR reactions. - Abstract: Nano-Silver powder has been studied as bi-functional electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline medium. Ag nano-powder has been prepared by a simple wet chemical method with Silver nitrate as precursor and Glucose as reducing agent. X-ray Diffraction and Scanning Electron Microscopy studies were carried out to characterize the Silver catalyst. Electrochemical oxygen evolution characterization shows anodic peak typically at the range between 0.350 and 0.514 V Vs Hg/HgO corresponding to Silver oxidation followed by the onset of oxygen evolution at 0.706 V. Oxygen reduction reaction studies carried out using Rotating Disc Electrode (RDE) confirm the four electron reaction mechanism. Ag catalyst shows promising characteristics for oxygen evolution and oxygen reduction

  11. Cooperative CO2 Absorption Isotherms from a Bifunctional Guanidine and Bifunctional Alcohol.

    Science.gov (United States)

    Steinhardt, Rachel; Hiew, Stanley C; Mohapatra, Hemakesh; Nguyen, Du; Oh, Zachary; Truong, Richard; Esser-Kahn, Aaron

    2017-12-27

    Designing new liquids for CO 2 absorption is a challenge in CO 2 removal. Here, achieving low regeneration energies while keeping high selectivity and large capacity are current challenges. Recent cooperative metal-organic frameworks have shown the potential to address many of these challenges. However, many absorbent systems and designs rely on liquid capture agents. We present herein a liquid absorption system which exhibits cooperative CO 2 absorption isotherms. Upon introduction, CO 2 uptake is initially suppressed, followed by an abrupt increase in absorption. The liquid consists of a bifunctional guanidine and bifunctional alcohol, which, when dissolved in bis(2-methoxyethyl) ether, forms a secondary viscous phase within seconds in response to increases in CO 2 . The precipitation of this second viscous phase drives CO 2 absorption from the gas phase. The isotherm of the bifunctional system differs starkly from the analogous monofunctional system, which exhibits limited CO 2 uptake across the same pressure range. In our system, CO 2 absorption is strongly solvent dependent. In DMSO, both systems exhibit hyperbolic isotherms and no precipitation occurs. Subsequent 1 H NMR experiments confirmed the formation of distinct alkylcarbonate species having either one or two molecules of CO 2 bound. The solvent and structure relationships derived from these results can be used to tailor new liquid absorption systems to the conditions of a given CO 2 separation process.

  12. New Insights in the Design of Bioactive Peptides and Chelating Agents for Imaging and Therapy in Oncology

    Directory of Open Access Journals (Sweden)

    Anna Lucia Tornesello

    2017-08-01

    Full Text Available Many synthetic peptides have been developed for diagnosis and therapy of human cancers based on their ability to target specific receptors on cancer cell surface or to penetrate the cell membrane. Chemical modifications of amino acid chains have significantly improved the biological activity, the stability and efficacy of peptide analogues currently employed as anticancer drugs or as molecular imaging tracers. The stability of somatostatin, integrins and bombesin analogues in the human body have been significantly increased by cyclization and/or insertion of non-natural amino acids in the peptide sequences. Moreover, the overall pharmacokinetic properties of such analogues and others (including cholecystokinin, vasoactive intestinal peptide and neurotensin analogues have been improved by PEGylation and glycosylation. Furthermore, conjugation of those peptide analogues to new linkers and bifunctional chelators (such as AAZTA, TETA, TRAP, NOPO etc., produced radiolabeled moieties with increased half life and higher binding affinity to the cognate receptors. This review describes the most important and recent chemical modifications introduced in the amino acid sequences as well as linkers and new bifunctional chelators which have significantly improved the specificity and sensitivity of peptides used in oncologic diagnosis and therapy.

  13. 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.

  14. 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

  15. 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...

  16. 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。

  17. Cyclic versus Noncyclic Chelating Scaffold for 89Zr-Labeled ZEGFR:2377 Affibody Bioconjugates Targeting Epidermal Growth Factor Receptor Overexpression.

    Science.gov (United States)

    Summer, Dominik; Garousi, Javad; Oroujeni, Maryam; Mitran, Bogdan; Andersson, Ken G; Vorobyeva, Anzhelika; Löfblom, John; Orlova, Anna; Tolmachev, Vladimir; Decristoforo, Clemens

    2018-01-02

    Zirconium-89 is an emerging radionuclide for positron emission tomography (PET) especially for biomolecules with slow pharmacokinetics as due to its longer half-life, in comparison to fluorine-18 and gallium-68, imaging at late time points is feasible. Desferrioxamine B (DFO), a linear bifunctional chelator (BFC) is mostly used for this radionuclide so far but shows limitations regarding stability. Our group recently reported on fusarinine C (FSC) with similar zirconium-89 complexing properties but potentially higher stability related to its cyclic structure. This study was designed to compare FSC and DFO head-to-head as bifunctional chelators for 89 Zr-radiolabeled EGFR-targeting ZEGFR:2377 affibody bioconjugates. 2377 and DFO-ZEGFR:2377 were evaluated regarding radiolabeling, in vitro stability, specificity, cell uptake, receptor affinity, biodistribution, and microPET-CT imaging. Both conjugates were efficiently labeled with zirconium-89 at room temperature but radiochemical yields increased substantially at elevated temperature, 85 °C. Both 89 Zr-FSC-ZEGFR:2377 and 89 Zr-DFO-ZEGFR:2377 revealed remarkable specificity, affinity and slow cell-line dependent internalization. Radiolabeling at 85 °C showed comparable results in A431 tumor xenografted mice with minor differences regarding blood clearance, tumor and liver uptake. In comparison 89 Zr-DFO-ZEGFR:2377, radiolabeled at room temperature, showed a significant difference regarding tumor-to-organ ratios. MicroPET-CT imaging studies of 89 Zr-FSC-ZEGFR:2377 as well as 89 Zr-DFO-ZEGFR:2377 confirmed these findings. In summary we were able to show that FSC is a suitable alternative to DFO for radiolabeling of biomolecules with zirconium-89. Furthermore, our findings indicate that 89 Zr-radiolabeling of DFO conjugates at higher temperature reduces off-chelate binding leading to significantly improved tumor-to-organ ratios and therefore enhancing image contrast.

  18. 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.)

  19. Bifunctional Phosphorus Dendrimers and Their Properties.

    Science.gov (United States)

    Caminade, Anne-Marie; Majoral, Jean-Pierre

    2016-04-23

    Dendrimers are hyperbranched and monodisperse macromolecules, generally considered as a special class of polymers, but synthesized step-by-step. Most dendrimers have a uniform structure, with a single type of terminal function. However, it is often desirable to have at least two different functional groups. This review will discuss the case of bifunctional phosphorus-containing dendrimers, and the consequences for their properties. Besides the terminal functions, dendritic structures may have also a function at the core, or linked off-center to the core, or at the core of dendrons (dendritic wedges). Association of two dendrons having different terminal functions leads to Janus dendrimers (two faces). The internal structure can also possess functional groups on one layer, or linked to one layer, or on several layers. Finally, there are several ways to have two types of terminal functions, besides the case of Janus dendrimers: either each terminal function bears two functions sequentially, or two different functions are linked to each terminal branching point. Examples of each type of structure will be given in this review, as well as practical uses of such sophisticated structures in the fields of fluorescence, catalysis, nanomaterials and biology.

  20. Engineering an antibody with picomolar affinity to DOTA chelates of multiple radionuclides for pretargeted radioimmunotherapy and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Orcutt, Kelly Davis; Slusarczyk, Adrian L. [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Cieslewicz, Maryelise [Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Ruiz-Yi, Benjamin [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Bhushan, Kumar R. [Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Boston, MA 02215 (United States); Frangioni, John V. [Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Boston, MA 02215 (United States); Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA 02215 (United States); Wittrup, K. Dane, E-mail: wittrup@mit.ed [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2011-02-15

    Introduction: In pretargeted radioimmunotherapy (PRIT), a bifunctional antibody is administered and allowed to pre-localize to tumor cells. Subsequently, a chelated radionuclide is administered and captured by cell-bound antibody while unbound hapten clears rapidly from the body. We aim to engineer high-affinity binders to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelates for use in PRIT applications. Methods: We mathematically modeled antibody and hapten pharmacokinetics to analyze hapten tumor retention as a function of hapten binding affinity. Motivated by model predictions, we used directed evolution and yeast surface display to affinity mature the 2D12.5 antibody to DOTA, reformatted as a single chain variable fragment (scFv). Results: Modeling predicts that for high antigen density and saturating bsAb dose, a hapten-binding affinity of 100 pM is needed for near-maximal hapten retention. We affinity matured 2D12.5 with an initial binding constant of about 10 nM to DOTA-yttrium chelates. Affinity maturation resulted in a 1000-fold affinity improvement to biotinylated DOTA-yttrium, yielding an 8.2{+-}1.9 picomolar binder. The high-affinity scFv binds DOTA complexes of lutetium and gadolinium with similar picomolar affinity and indium chelates with low nanomolar affinity. When engineered into a bispecific antibody construct targeting carcinoembryonic antigen, pretargeted high-affinity scFv results in significantly higher tumor retention of a {sup 111}In-DOTA hapten compared to pretargeted wild-type scFv in a xenograft mouse model. Conclusions: We have engineered a versatile, high-affinity, DOTA-chelate-binding scFv. We anticipate it will prove useful in developing pretargeted imaging and therapy protocols to exploit the potential of a variety of radiometals.

  1. Carbon in bifunctional air electrodes in alkaline solution

    International Nuclear Information System (INIS)

    Tryk, D.; Aldred, W.; Yeager, E.

    1983-01-01

    Bifunctional O 2 electrodes can be used both to reduce and to generate O 2 in rechargeable metal-air batteries and fuel cells. The factors controlling the O 2 reduction and generation reactions in gas-diffusional bifunctional O 2 electrodes are discussed. The resistance of such electrodes, as established from voltammetry curves, has been found to increase markedly during anodic polarization and to be dependent upon the electrode fabrication technique. Carbon blacks with more graphitic structure than Shawinigan black have been found to be more resistant to electro-oxidation. The further extension of cycle life of bifunctional electrodes using carbon is critically dependent on finding more oxidation-resistant carbons that at the same time have other surface properties meeting the requirements for catalyzed gas-diffusion electrodes

  2. Single flexible nanofiber to simultaneously realize electricity-magnetism bifunctionality

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ming; Sheng, Shujuan; Ma, Qianli; Lv, Nan; Yu, Wensheng; Wang, Jinxian; Dong, Xiangting; Liu, Guixia, E-mail: wenshengyu2009@sina.com, E-mail: dongxiangting888@163.com [Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun (China)

    2016-03-15

    In order to develop new-typed multifunctional composite nanofibers, PANI/Fe{sub 3}O{sub 4}/PVP flexible bifunctional composite nanofibers with simultaneous electrical conduction and magnetism have been successfully fabricated via a facile electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of polyaniline (PANI) and Fe{sub 3}O{sub 4} nanoparticles (NPs). The bifunctional composite nanofibers simultaneously possess excellent electrical conductivity and magnetic properties. The electrical conductivity reaches up to the order of 10{sup -3} S·cm{sup -1}. The electrical conductivity and saturation magnetization of the composite nanofibers can be respectively tuned by adding various amounts of PANI and Fe{sub 3}O{sub 4} NPs. The obtained electricity-magnetism bifunctional composite nanofibers are expected to possess many potential applications in areas such as electromagnetic interference shielding, special coating, microwave absorption, molecular electronics and future nanomechanics. More importantly, the design concept and construct technique are of universal significance to fabricate other bifunctional one-dimensional nanostructures. (author)

  3. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    NARCIS (Netherlands)

    Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2015-01-01

    The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts(1-4). Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon

  4. Synthesis and characterization of bi-functional magneto-luminescent ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 128; Issue 7. Synthesis and characterization of bi-functional magneto-luminescent Fe₃O₄ @ SiO₂ @ NaLuF₄ :Eu³⁺ hybrid core / shell nanospheres. JIGMET LADOL HEENA KHAJURIA HAQ NAWAZ SHEIKH YUGAL KHAJURIA. Regular Article Volume 128 Issue ...

  5. Molecular Modeling of Bifunctional Chelate Peptide Conjugates. 1. Copper and Indium Parameters for the AMBER Force Field

    DEFF Research Database (Denmark)

    Reichert, David E.; Norrby, Per-Ola; Welch, Michael J.

    2001-01-01

    In this work we describe the development of parameters for In(III) and Cu(II) for the AMBER* force field as found in the modeling package MacroModel. These parameters were developed using automated procedures from a combination of crystallographic structures and ab initio calculations. The new pa...

  6. 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.

  7. Evaluation of nitrogen-rich macrocyclic ligands for the chelation of therapeutic bismuth radioisotopes.

    Science.gov (United States)

    Wilson, Justin J; Ferrier, Maryline; Radchenko, Valery; Maassen, Joel R; Engle, Jonathan W; Batista, Enrique R; Martin, Richard L; Nortier, Francois M; Fassbender, Michael E; John, Kevin D; Birnbaum, Eva R

    2015-05-01

    The use of α-emitting isotopes for radionuclide therapy is a promising treatment strategy for small micro-metastatic disease. The radioisotope (213)Bi is a nuclide that has found substantial use for targeted α-therapy (TAT). The relatively unexplored aqueous chemistry of Bi(3+), however, hinders the development of bifunctional chelating agents that can successfully deliver these Bi radioisotopes to the tumor cells. Here, a novel series of nitrogen-rich macrocyclic ligands is explored for their potential use as Bi-selective chelating agents. The ligands, 1,4,7,10-tetrakis(pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane (L(py)), 1,4,7,10-tetrakis(3-pyridazylmethyl)-1,4,7,10-tetraazacyclododecane (L(pyd)), 1,4,7,10-tetrakis(4-pyrimidylmethyl)-1,4,7,10-tetraazacyclododecane (L(pyr)), and 1,4,7,10-tetrakis(2-pyrazinylmethyl)-1,4,7,10-tetraazacyclododecane (L(pz)), were prepared by a previously reported method and investigated here for their abilities to bind Bi radioisotopes. The commercially available and commonly used ligands 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and N-[(R)-2-amino-3-(p-isothiocyanato-phenyl)propyl]-trans-(S,S)- cyclohexane-1,2-diamine-N,N,N',N",N"-pentaacetic acid (CHX-A''-DTPA) were also explored for comparative purposes. Radio-thin-layer chromatography (TLC) was used to measure the binding kinetics and stabilities of the complexes formed. The long-lived isotope, (207)Bi (t(1/2)=32 years), was used for these studies. Density functional theory (DFT) calculations were also employed to probe the ligand interactions with Bi(3+) and the generator parent ion Ac(3+). In contrast to DOTA and CHX-A''-DTPA, these nitrogen-rich macrocycles selectively chelate Bi(3+) in the presence of the parent isotope Ac(3+). Among the four tested, L(py) was found to exhibit optimal Bi(3+)-binding kinetics and complex stability. L(py) complexes Bi(3+) more rapidly than DOTA, yet the resulting complexes are of similar stability. DFT calculations

  8. 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.

  9. 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.

  10. 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.

  11. 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 ...

  12. Why Does Alkylation of the N–H Functionality within M/NH Bifunctional Noyori-Type Catalysts Lead to Turnover?

    International Nuclear Information System (INIS)

    Dub, Pavel; Gordon, John Cameron; Scott, Brian Lindley

    2017-01-01

    Molecular metal/NH bifunctional Noyori-type catalysts are remarkable in that they are among the most efficient artificial catalysts developed to date for the hydrogenation of carbonyl functionalities (loadings up to ~10 –5 mol %). In addition, these catalysts typically exhibit high C=O/C=C chemo- and enantioselectivities. This unique set of properties is traditionally associated with the operation of an unconventional mechanism for homogeneous catalysts in which the chelating ligand plays a key role in facilitating the catalytic reaction and enabling the aforementioned selectivities by delivering/accepting a proton (H + ) via its N–H bond cleavage/formation. A recently revised mechanism of the Noyori hydrogenation reaction (Dub, P. A. et al. J. Am. Chem. Soc. 2014, 136, 3505) suggests that the N–H bond is not cleaved but serves to stabilize the turnover-determining transition states (TDTSs) via strong N–H···O hydrogen-bonding interactions (HBIs). Here, the present paper shows that this is consistent with the largely ignored experimental fact that alkylation of the N–H functionality within M/NH bifunctional Noyori-type catalysts leads to detrimental catalytic activity. Finally, the purpose of this work is to demonstrate that decreasing the strength of this HBI, ultimately to the limit of its complete absence, are conditions under which the same alkylation may lead to beneficial catalytic activity.

  13. Why Does Alkylation of the N-H Functionality within M/NH Bifunctional Noyori-Type Catalysts Lead to Turnover?

    Science.gov (United States)

    Dub, Pavel A; Scott, Brian L; Gordon, John C

    2017-01-25

    Molecular metal/NH bifunctional Noyori-type catalysts are remarkable in that they are among the most efficient artificial catalysts developed to date for the hydrogenation of carbonyl functionalities (loadings up to ∼10 -5 mol %). In addition, these catalysts typically exhibit high C═O/C═C chemo- and enantioselectivities. This unique set of properties is traditionally associated with the operation of an unconventional mechanism for homogeneous catalysts in which the chelating ligand plays a key role in facilitating the catalytic reaction and enabling the aforementioned selectivities by delivering/accepting a proton (H + ) via its N-H bond cleavage/formation. A recently revised mechanism of the Noyori hydrogenation reaction (Dub, P. A. et al. J. Am. Chem. Soc. 2014, 136, 3505) suggests that the N-H bond is not cleaved but serves to stabilize the turnover-determining transition states (TDTSs) via strong N-H···O hydrogen-bonding interactions (HBIs). The present paper shows that this is consistent with the largely ignored experimental fact that alkylation of the N-H functionality within M/NH bifunctional Noyori-type catalysts leads to detrimental catalytic activity. The purpose of this work is to demonstrate that decreasing the strength of this HBI, ultimately to the limit of its complete absence, are conditions under which the same alkylation may lead to beneficial catalytic activity.

  14. 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.

  15. The aminoindanol core as a key scaffold in bifunctional organocatalysts

    Directory of Open Access Journals (Sweden)

    Isaac G. Sonsona

    2016-03-01

    Full Text Available The 1,2-aminoindanol scaffold has been found to be very efficient, enhancing the enantioselectivity when present in organocatalysts. This may be explained by its ability to induce a bifunctional activation of the substrates involved in the reaction. Thus, it is easy to find hydrogen-bonding organocatalysts ((thioureas, squaramides, quinolinium thioamide, etc. in the literature containing this favored structural core. They have been successfully employed in reactions such as Friedel–Crafts alkylation, Michael addition, Diels–Alder and aza-Henry reactions. However, the 1,2-aminoindanol core incorporated into proline derivatives has been scarcely explored. Herein, the most representative and illustrative examples are compiled and this review will be mainly focused on the cases where the aminoindanol moiety confers bifunctionality to the organocatalysts.

  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. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    Science.gov (United States)

    Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2015-12-01

    The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called intimacy criterion has dictated the maximum distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometre precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites. Here we show for a bifunctional catalyst—comprising an intimate mixture of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder—that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains platinum on the binder, that is, with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon molecules that are typically derived from alternative sources, such as gas-to-liquid technology, vegetable oil or algal oil, should benefit especially from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, we anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts.

  18. Targeting Prostate Cancer with Bifunctional Modulators of the Androgen Receptor

    Science.gov (United States)

    2015-06-01

    References 1. Ramamoorthy S, Cidlowski JA. Exploring the molecular mecha- nisms of glucocorticoid receptor action from sensitivity to resis- tance. Endocr... actions of glucocorti- coids. Proc Natl Acad Sci USA. 2012;109:11776–11781. 16. van Rossum EF, van den Akker EL. Glucocorticoid resistance. En- docr Dev...we continued the use of glucocorticoid receptor (GR) as the model in which to test the bifunctional recruitment model. Given the modular nature of om

  19. Is Root Catalase a Bifunctional Catalase-Peroxidase?

    Science.gov (United States)

    Chioti, Vasileia; Zervoudakis, George

    2017-05-25

    Plant catalases exhibit spatial and temporal distribution of their activity. Moreover, except from the typical monofunctional catalase, a bifunctional catalase-peroxidase has been reported. The aim of this study was to investigate whether the leaf and root catalases from six different plant species ( Lactuca sativa , Cichorium endivia , Apium graveolens , Petroselinum crispum, Lycopersicon esculentum , and Solanum melongena ) correspond to the monofunctional or the bifunctional type based on their sensitivity to the inhibitor 3-amino-1,2,4-triazole (3-AT). The leaf catalases from all species seem to be monofunctional since they are very sensitive to 3-AT. On the other hand, the root enzymes from Lactuca sativa , Cichorium endivia , Lycopersicon esculentum , and Solanum melongena seem to be bifunctional catalase-peroxidases, considering that they are relatively insensitive to 3-AT, whereas the catalases from Apium graveolens and Petroselinum crispum display the same monofunctional characteristics as the leaves' enzymes. The leaf catalase activity is usually higher ( Lactuca sativa , Petroselinum crispum , and Solanum melongena ) or similar ( Cichorium endivia and Apium graveolens ) to the root one, except for the enzyme from Lycopersicon esculentum , while in all plant species the leaf protein concentration is significantly higher than the root protein concentration. These results suggest that there are differences between leaf and root catalases-differences that may correspond to their physiological role.

  20. Simple and general procedure for the synthesis of semi-rigid chelating agents for radiometal complexation studies and its application to semi-rigid functionalised ligands (BCA) synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Loussouarn, A.; Faivre-Chauvet, A.; Chatal, J.-F.; Gestin, J.-F. [INSERM, Nantes (France). Inst. de Biologie

    1999-07-01

    Immunotherapy with radiolabeled antibodies should allow fairly specific targeting of certain cancers. However, iodine-131 may not be the best isotope for tumour therapy because of its limited specific activity, low beta-energy, relatively long half-life and strong gamma emission. Another approach to improve therapeutic efficacy is the use of replacement isotopes with better physical properties. Chelators that can hold radiometals with high stability under physiological conditions are essential to avoid excessive radiation damage to non-target cells. Moreover, the development of new bifunctional chelating agents is essential for this purpose. Accordingly, our efforts have been directed, for several years, to the synthesis of original chelating agents likely to form stable complexes in vivo with the numerous potential candidates for such applications. The stability of a non-macrocyclic ligand can be favourably influenced by the preorganization of the open chain. In fact, a semi-rigid structure such as that of trans-1,2-diaminocyclohexane limits the rotation of the ethylene bridge, so that the purpose of the cyclohexane design is to preorient the four pendent arms in a skew position. Therefore, we have developed a new simple and efficient synthesis pathway from trans-1,2-diaminocyclohexane to provide access to a new class of semi-rigid chelating agents. This same reactional scheme will be apply to our reactional intermediary, (1R{sup *}, 2R{sup *}, 4S{sup *})-4-acetamido-1,2-diaminocyclohexane dihydrochloride, which will allow the synthesis of these same chelating agents, though functionalised back of the cycle by a termination allowed coupling to an antibody or any other biological substance such as a hapten. (orig.)

  1. Simple and general procedure for the synthesis of semi-rigid chelating agents for radiometal complexation studies and its application to semi-rigid functionalised ligands (BCA) synthesis

    International Nuclear Information System (INIS)

    Loussouarn, A.; Faivre-Chauvet, A.; Chatal, J.-F.; Gestin, J.-F.

    1999-01-01

    Immunotherapy with radiolabeled antibodies should allow fairly specific targeting of certain cancers. However, iodine-131 may not be the best isotope for tumour therapy because of its limited specific activity, low beta-energy, relatively long half-life and strong gamma emission. Another approach to improve therapeutic efficacy is the use of replacement isotopes with better physical properties. Chelators that can hold radiometals with high stability under physiological conditions are essential to avoid excessive radiation damage to non-target cells. Moreover, the development of new bifunctional chelating agents is essential for this purpose. Accordingly, our efforts have been directed, for several years, to the synthesis of original chelating agents likely to form stable complexes in vivo with the numerous potential candidates for such applications. The stability of a non-macrocyclic ligand can be favourably influenced by the preorganization of the open chain. In fact, a semi-rigid structure such as that of trans-1,2-diaminocyclohexane limits the rotation of the ethylene bridge, so that the purpose of the cyclohexane design is to preorient the four pendent arms in a skew position. Therefore, we have developed a new simple and efficient synthesis pathway from trans-1,2-diaminocyclohexane to provide access to a new class of semi-rigid chelating agents. This same reactional scheme will be apply to our reactional intermediary, (1R * , 2R * , 4S * )-4-acetamido-1,2-diaminocyclohexane dihydrochloride, which will allow the synthesis of these same chelating agents, though functionalised back of the cycle by a termination allowed coupling to an antibody or any other biological substance such as a hapten. (orig.)

  2. 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.

  3. 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

  4. 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

  5. Microwave assisted bi-functional activation of -bromo-tert-alcohols

    Indian Academy of Sciences (India)

    -Bromo-tert-alcohols; microwave; bi-functional activation; ZnS; flavour compounds. ... A concurrent bi-functional activation of trans-vicinal bromo- and hydroxyl groups with ZnS is elucidated. This is a new ... Spice and Flavour Science Department, CSIR-Central Food Technological Research Institute, Mysore 570 020, India ...

  6. Coordination Chemistry of Bifunctional Chemical Agents Designed for Applications in64Cu PET Imaging for Alzheimer's Disease.

    Science.gov (United States)

    Sharma, Anuj K; Schultz, Jason W; Prior, John T; Rath, Nigam P; Mirica, Liviu M

    2017-11-20

    Positron emission tomography (PET) is emerging as one of the most important diagnostic tools for brain imaging, yet the most commonly used radioisotopes in PET imaging, 11 C and 18 F, have short half-lives, and their usage is thus somewhat limited. By comparison, the 64 Cu radionuclide has a half-life of 12.7 h, which is ideal for administering and imaging purposes. In spite of appreciable research efforts, high-affinity copper chelators suitable for brain imaging applications are still lacking. Herein, we present the synthesis and characterization of a series of bifunctional compounds (BFCs) based on macrocyclic 1,4,7-triazacyclononane and 2,11-diaza[3.3](2,6)pyridinophane ligand frameworks that exhibit a high affinity for Cu 2+ ions. In addition, these BFCs contain a 2-phenylbenzothiazole fragment that is known to interact tightly with amyloid β fibrillar aggregates. Determination of the protonation constants (pK a values) and stability constants (log β values) of these BFCs, as well as characterization of the isolated copper complexes using X-ray crystallography, electron paramagnetic resonance spectroscopy, and electrochemical studies, suggests that these BFCs exhibit desirable properties for the development of novel 64 Cu PET imaging agents for Alzheimer's disease.

  7. Achieving bifunctional cloak via combination of passive and active schemes

    Science.gov (United States)

    Lan, Chuwen; Bi, Ke; Gao, Zehua; Li, Bo; Zhou, Ji

    2016-11-01

    In this study, a simple and delicate approach to realizing manipulation of multi-physics field simultaneously through combination of passive and active schemes is proposed. In the design, one physical field is manipulated with passive scheme while the other with active scheme. As a proof of this concept, a bifunctional device is designed and fabricated to behave as electric and thermal invisibility cloak simultaneously. It is found that the experimental results are consistent with the simulated ones well, confirming the feasibility of our method. Furthermore, the proposed method could also be extended to other multi-physics fields, which might lead to potential applications in thermal, electric, and acoustic areas.

  8. 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...

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Novel magnetic-fluorescent bifunctional Janus nanofiber membrane

    Science.gov (United States)

    Wang, Qiutong; Geng, Yuting; Li, Jianhao; Yin, Meizhen; Hu, Yiseng; Liu, Yangxiu; Pan, Kai

    2018-04-01

    Magnetic-fluorescent bifunctional materials have received global attention owing to their potential in many fields. Herein, we reported a novel magnetic-fluorescent bifunctional Janus nanofiber membrane (NFM) by adding the as-prepared magnetic CoFe2O4 nanoparticles into the polyacrylonitrile (PAN) side (m-PAN) and the fluorescent molecules of 1,8-naphthalene anhydride (1,8-NAD) into the polyvinylpyrrolidone (PVP) side (f-PVP) via electrospinning method. The obtained m-PAN/f-PVP Janus NFM exhibited excellent magnetic performance and high fluorescent properties due to the unique structure. Compared with the m-PAN/f-PVP composite NFM, the Janus NFM showed higher fluorescent performance because the fluorescent molecules were isolated from the magnetic nanoparticles. In addition, the Janus NFM not only maintain the good self-supporting state in water but also realize a directional movement attracted by a magnet. The unique structure of Janus nanofiber is of great importance and demonstrates great potential applications.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. Biomedical Applications of Gold Nanoparticles Functionalized Using Hetero-Bifunctional Poly(ethylene glycol) Spacer

    National Research Council Canada - National Science Library

    Fu, Wei; Shenoy, Dinesh; Li, Jane; Crasto, Curtis; Jones, Graham; Dimarzio, Charles; Sridhar, Srinivas; Amiji, Mansoor

    2005-01-01

    To increase the targeting potential, circulation time, and the flexibility of surface-attached biomedically-relevant ligands on gold nanoparticles, hetero-bifunctional poly(ethylene glycol) (PEG, MW 1,500...

  20. 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.

  1. 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)

  2. Synthesis of deuterium-labeled analogs of the lipid hydroperoxide-derived bifunctional electrophile 4-oxo-2(E)-nonenal

    OpenAIRE

    Arora, Jasbir S.; Oe, Tomoyuki; Blair, Ian A.

    2011-01-01

    Lipid hydroperoxides undergo homolytic decomposition into the bifunctional 4-hydroxy-2(E)-nonenal and 4-oxo-2(E)-nonenal (ONE). These bifunctional electrophiles are highly reactive and can readily modify intracellular molecules including glutathione (GSH), deoxyribonucleic acid (DNA) and proteins. Lipid hydroperoxide-derived bifunctional electrophiles are thought to contribute to the pathogenesis of a number of diseases. ONE is an α,β-unsaturated aldehyde that can react in multiple ways and w...

  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. Mechanish of dTTP Inhibition of the Bifunctional dCTP Deaminase:dUTPase Encoded by Mycobacterium tuberculosis

    DEFF Research Database (Denmark)

    Helt, Signe Smedegaard; Thymark, Majbritt; Harris, Pernille

    2008-01-01

    Recombinant deoxycytidine triphosphate (dCTP) deaminase from Mycobacterium tuberculosis was produced in Escherichia coli and purified. The enzyme proved to be a bifunctional dCTP deaminase:deoxyuridine triphosphatase. As such, the M. tuberculosis enzyme is the second bifunctional enzyme to be cha......Recombinant deoxycytidine triphosphate (dCTP) deaminase from Mycobacterium tuberculosis was produced in Escherichia coli and purified. The enzyme proved to be a bifunctional dCTP deaminase:deoxyuridine triphosphatase. As such, the M. tuberculosis enzyme is the second bifunctional enzyme...

  5. 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)

  6. 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.

  7. 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 ...

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  13. 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

  14. 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

  15. Chapter 19. Design and evaluation of potential 99mTc radiopharmaceuticals based on the Tc-Carbonyl, 4 + 1 mixed ligand chelate system and Tc-nitrido approaches

    International Nuclear Information System (INIS)

    Giglio, J.; Muslera, A.; Leon, E.; Paolino, A.; Leon, A.; Rey, A.; Incerti, M.; Fernandez, R.; Manta, E.; Brugnini, A.; Chabalgoity, A.

    2007-01-01

    The aim of the work was to explore the possibilities of the novel labelling strategies in the development of 99m Tc labelled small biomolecules. Different steps required to fulfil this objective were undertaken: organic synthesis of glucose derivatives, optimization of labelling and in vitro and in vivo evaluation of Rd peptides and anne xin 13 derivatives using either the Hyonic bifunctional ligand, the Tc-tricarbonyl, the 4 + 1 mixed ligand or the Tc(V)-nitri do approaches. Glucose-O-hexyl bromide, glucose- O-butylbromide and glucose-O-butylamine were successfully synthesized, opening the possibility of introducing different chelators according to the desired labelling procedure. c(RGDyK) derivatives bearing different chelators were labelled with 99m Tc using novel approaches and evaluated both in vitro and in vivo in order to compare the effect of the chelator and labelling method on the physicochemical and biological behaviour. Annexin 13 peptides were also labelled using the HYNIC and Tc(I)-tricarbonyl approaches. A primary evaluation in normal animals and in a model of cardiac apoptosis is also presented. Cooperation with other participants was crucial to develop this work. (author)

  16. 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.

  17. Single flexible nanofiber to achieve simultaneous photoluminescence-electrical conductivity bifunctionality.

    Science.gov (United States)

    Sheng, Shujuan; Ma, Qianli; Dong, Xiangting; Lv, Nan; Wang, Jinxian; Yu, Wensheng; Liu, Guixia

    2015-02-01

    In order to develop new-type multifunctional composite nanofibers, Eu(BA)3 phen/PANI/PVP bifunctional composite nanofibers with simultaneous photoluminescence and electrical conductivity have been successfully fabricated via electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of Eu(BA)3 phen and polyaniline (PANI). X-Ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), fluorescence spectroscopy and a Hall effect measurement system are used to characterize the morphology and properties of the composite nanofibers. The results indicate that the bifunctional composite nanofibers simultaneously possess excellent photoluminescence and electrical conductivity. Fluorescence emission peaks of Eu(3+) ions are observed in the Eu(BA)3 phen/PANI/PVP photoluminescence-electrical conductivity bifunctional composite nanofibers. The electrical conductivity reaches up to the order of 10(-3)  S/cm. The luminescent intensity and electrical conductivity of the composite nanofibers can be tuned by adjusting the amounts of Eu(BA)3 phen and PANI. The obtained photoluminescence-electrical conductivity bifunctional composite nanofibers are expected to possess many potential applications in areas such as microwave absorption, molecular electronics, biomedicine and future nanomechanics. More importantly, the design concept and construction technique are of universal significance to fabricate other bifunctional one-dimensional naonomaterials. Copyright © 2014 John Wiley & Sons, Ltd.

  18. Bioinspired Bifunctional Membrane for Efficient Clean Water Generation.

    Science.gov (United States)

    Liu, Yang; Lou, Jinwei; Ni, Mengtian; Song, Chengyi; Wu, Jianbo; Dasgupta, Neil P; Tao, Peng; Shang, Wen; Deng, Tao

    2016-01-13

    Solving the problems of water pollution and water shortage is an urgent need for the sustainable development of modern society. Different approaches, including distillation, filtration, and photocatalytic degradation, have been developed for the purification of contaminated water and the generation of clean water. In this study, we explored a new approach that uses solar light for both water purification and clean water generation. A bifunctional membrane consisting of a top layer of TiO2 nanoparticles (NPs), a middle layer of Au NPs, and a bottom layer of anodized aluminum oxide (AAO) was designed and fabricated through multiple filtration processes. Such a design enables both TiO2 NP-based photocatalytic function and Au NP-based solar-driven plasmonic evaporation. With the integration of these two functions into a single membrane, both the purification of contaminated water through photocatalytic degradation and the generation of clean water through evaporation were demonstrated using simulated solar illumination. Such a demonstration should also help open up a new strategy for maximizing solar energy conversion and utilization.

  19. From Food Waste to Efficient Bifunctional Nonprecious Electrocatalyst.

    Science.gov (United States)

    Hof, Ferdinand; Boni, Alessandro; Valenti, Giovanni; Huang, Kai; Paolucci, Francesco; Pénicaud, Alain

    2017-11-02

    Synergy between graphitic nanocarbon, obtainable from food waste through cracking of biomethane, and iron oxide nanoparticles provides access to efficient bifunctional electro catalysts. Dissolution of potassium-intercalated graphitic nanocarbons yields graphenide solutions with calibrated, small lateral size-reduced graphenes that are used subsequently as reducing agents of iron metal salts. This results in the strong binding of small size (2-5 nm) nanoparticles on the carbon framework homogeneously within the composite material, accessibility of the catalytic centers, and good conductivity provided by the underlying carbon framework. The iron oxide nanocarbon electrocatalyst performances are highlighted by the overall overpotential of approximately 1 V needed to reach the benchmark threshold of 10 mA cm -2 for the oxygen reduction reaction and the particular activity towards oxygen evolution reaction (η≈0.4 V at 10 mA cm -2 ), comparable to that of the precious RuO 2 and IrO 2 catalysts. This iron oxide/nanocarbon electrocatalyst is versatile, remarkably active, stable, and truly sustainable. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. A conserved regulatory mechanism in bifunctional biotin protein ligases.

    Science.gov (United States)

    Wang, Jingheng; Beckett, Dorothy

    2017-08-01

    Class II bifunctional biotin protein ligases (BirA), which catalyze post-translational biotinylation and repress transcription initiation, are broadly distributed in eubacteria and archaea. However, it is unclear if these proteins all share the same molecular mechanism of transcription regulation. In Escherichia coli the corepressor biotinoyl-5'-AMP (bio-5'-AMP), which is also the intermediate in biotin transfer, promotes operator binding and resulting transcription repression by enhancing BirA dimerization. Like E. coli BirA (EcBirA), Staphylococcus aureus, and Bacillus subtilis BirA (Sa and BsBirA) repress transcription in vivo in a biotin-dependent manner. In this work, sedimentation equilibrium measurements were performed to investigate the molecular basis of this biotin-responsive transcription regulation. The results reveal that, as observed for EcBirA, Sa, and BsBirA dimerization reactions are significantly enhanced by bio-5'-AMP binding. Thus, the molecular mechanism of the Biotin Regulatory System is conserved in the biotin repressors from these three organisms. © 2017 The Protein Society.

  1. Bifunctional avidin with covalently modifiable ligand binding site.

    Directory of Open Access Journals (Sweden)

    Jenni Leppiniemi

    Full Text Available The extensive use of avidin and streptavidin in life sciences originates from the extraordinary tight biotin-binding affinity of these tetrameric proteins. Numerous studies have been performed to modify the biotin-binding affinity of (streptavidin to improve the existing applications. Even so, (streptavidin greatly favours its natural ligand, biotin. Here we engineered the biotin-binding pocket of avidin with a single point mutation S16C and thus introduced a chemically active thiol group, which could be covalently coupled with thiol-reactive molecules. This approach was applied to the previously reported bivalent dual chain avidin by modifying one binding site while preserving the other one intact. Maleimide was then coupled to the modified binding site resulting in a decrease in biotin affinity. Furthermore, we showed that this thiol could be covalently coupled to other maleimide derivatives, for instance fluorescent labels, allowing intratetrameric FRET. The bifunctional avidins described here provide improved and novel tools for applications such as the biofunctionalization of surfaces.

  2. A comparative study of thermodynamics in synergistic extraction of hexavalent plutonium by HTTA and HPMBP using mono- and bi-functional neutral donors

    International Nuclear Information System (INIS)

    Lohithakshan, K.V.; Mithapara, P.D.; Pai, S.A.; Aggarwal, S.K.

    1996-01-01

    Synergistic extraction of hexavalent plutonium was studied from HNO 3 medium (0.05 M) with HTTA and various neutral donors viz. DPSO, TBP, TOPO (monofunctional) and DBDECMP, DHDECMP, CMPO (bifunctional) using benzene as a diluent. Thermodynamic parameters (Δ G, Δ H, Δ S) were evaluated at 298 K from the experiments performed at four fixed temperatures in 288 to 318 K range. These were compared with the corresponding values reported earlier for Pu(VI) + HPMBP + neutral donor system. The net negative enthalpy changes with HTTA were observed to be low as compared to those with HPMBP. The net entropy changes were found to be either negligibly small (in cases of DPSO, TBP, DBDECMP, DHDECMP) or positive (in cases of CMPO, TOPO) with HTTA in comparison to large negative values with HPMBP. These results were interpreted in terms of different organic phase adduct formation reaction mechanisms i.e. substitution in HTTA vs. addition in HPMBP. Further, the lower net enthalpy changes with HTTA were explained due to a part of the energy used in release of water molecules bonded to plutonium in the plutonium chelate. (orig.)

  3. 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

  4. 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.

  5. Polymer-Supported Reagents: The Role of Bifunctionality in the Design of Ion-Selective Complexants

    Energy Technology Data Exchange (ETDEWEB)

    Alexandratos, S. D.

    2001-06-01

    The importance of multi-functionality in the preparation of ion-selective polymers is evident from the structure of enzymes where specific metal ions are bound through cooperative interactions among different amino acids. In synthetic polymers, ionic selectivity is enhanced when a chemical reaction is superimposed on an ion-exchange process. The concept of reactive ion exchange has been extended through the synthesis of crosslinked polymers whose metal ion selectivity is a function of reduction, coordination or precipitation reactions as determined by various covalently bound ligands. Development of three classes of dual mechanism bifunctional polymers, a new series of bifunctional diphosphonate polymers, and novel bifunctional ion-selective polymers with enhanced ionic accessibility has been accomplished.

  6. 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.

  7. Bifunctional Pt-Si Alloys for Small Organic Molecule Electro-oxidation

    DEFF Research Database (Denmark)

    Permyakova, Anastasia Aleksandrovna; Suntivich, Jin; Han, Binghong

    Designing highly active catalysts for electro-oxidation of small organic molecules can help to reduce the anodic overpotential for more efficient utilization of hydrocarbon fuels. The challenge in developing more active electrocatalysts for electro-oxidation reactions is to satisfy the stringent...... bifunctional requirement, which demands both adsorption and water oxidation sites. In this contribution, we explore the possibility of using Pt-Si alloys to fulfill this bifunctional requirement. Silicon, a highly oxophillic element, is alloyed into Pt as a site for water oxidation, while Pt serves as a CO...

  8. Janus nanobelts: fabrication, structure and enhanced magnetic-fluorescent bifunctional performance

    Science.gov (United States)

    Ma, Qianli; Yu, Wensheng; Dong, Xiangting; Wang, Jinxian; Liu, Guixia

    2014-02-01

    A new nanostructure of magnetic-fluorescent bifunctional Janus nanobelts with Fe3O4/PMMA as one half and Tb(BA)3phen/PMMA as the other half has been successfully fabricated by a specially designed parallel spinneret electrospinning technology. The morphology and properties of the final products were investigated in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), biological microscopy (BM), vibrating sample magnetometry (VSM) and fluorescence spectroscopy. The results revealed that the [Fe3O4/PMMA]//[Tb(BA)3phen/PMMA] magnetic-fluorescent bifunctional Janus nanobelts possess superior magnetic and fluorescent properties due to their special nanostructure. Compared with Fe3O4/Tb(BA)3phen/PMMA composite nanobelts, the magnetic-fluorescent bifunctional Janus nanobelts provided better performance. The new magnetic-fluorescent bifunctional Janus nanobelts have potential applications in novel nano-bio-label materials, drug target delivery materials and future nanodevices due to their excellent magnetic-fluorescent properties, flexibility and insolubility. Moreover, the construction technique for the Janus nanobelts is of universal significance for the fabrication of other multifunctional Janus nanobelts.A new nanostructure of magnetic-fluorescent bifunctional Janus nanobelts with Fe3O4/PMMA as one half and Tb(BA)3phen/PMMA as the other half has been successfully fabricated by a specially designed parallel spinneret electrospinning technology. The morphology and properties of the final products were investigated in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), biological microscopy (BM), vibrating sample magnetometry (VSM) and fluorescence spectroscopy. The results revealed that the [Fe3O4/PMMA]//[Tb(BA)3phen/PMMA] magnetic-fluorescent bifunctional Janus nanobelts possess superior magnetic and fluorescent properties due to their special

  9. 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.

  10. 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.

  11. 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.

  12. Reaction Current Phenomenon in Bifunctional Catalytic Metal-Semiconductor Nanostructures

    Science.gov (United States)

    Hashemian, Mohammad Amin

    Energy transfer processes accompany every elementary step of catalytic chemical processes on material surface including molecular adsorption and dissociation on atoms, interactions between intermediates, and desorption of reaction products from the catalyst surface. Therefore, detailed understanding of these processes on the molecular level is of great fundamental and practical interest in energy-related applications of nanomaterials. Two main mechanisms of energy transfer from adsorbed particles to a surface are known: (i) adiabatic via excitation of quantized lattice vibrations (phonons) and (ii) non-adiabatic via electronic excitations (electron/hole pairs). Electronic excitations play a key role in nanocatalysis, and it was recently shown that they can be efficiently detected and studied using Schottky-type catalytic nanostructures in the form of measureable electrical currents (chemicurrents) in an external electrical circuit. These nanostructures typically contain an electrically continuous nanocathode layers made of a catalytic metal deposited on a semiconductor substrate. The goal of this research is to study the direct observations of hot electron currents (chemicurrents) in catalytic Schottky structures, using a continuous mesh-like Pt nanofilm grown onto a mesoporous TiO2 substrate. Such devices showed qualitatively different and more diverse signal properties, compared to the earlier devices using smooth substrates, which could only be explained on the basis of bifunctionality. In particular, it was necessary to suggest that different stages of the reaction are occurring on both phases of the catalytic structure. Analysis of the signal behavior also led to discovery of a formerly unknown (very slow) mode of the oxyhydrogen reaction on the Pt/TiO2(por) system occurring at room temperature. This slow mode was producing surprisingly large stationary chemicurrents in the range 10--50 microA/cm2. Results of the chemicurrent measurements for the bifunctional

  13. Physical properties of bifunctional BST/LSMO nanocomposites

    Science.gov (United States)

    Beltran-Huarac, Juan; Martinez, Ricardo; Morell, Gerardo

    2014-02-01

    We report the fabrication of bifunctional nanocomposites consisting of ferroelectric Ba0.7Sr0.3TiO3 (BST) and ferromagnetic La0.67Sr0.33MnO3 (LSMO) at different concentrations via a high-temperature solid state route. The structural, dielectric, electrical, magnetodielectric (MD), magnetoelectric (ME) and magnetic properties of BST/LSMO nanocomposites were systematically investigated over a wide range of temperatures and frequencies. The X-Ray Diffraction analyses reveal the nanocrystalline nature of the heterostructures, wherein both perovskite phases co-exist. No parasitic phases were observed. The study of the dielectric properties shows that the nanocomposites exhibit relaxor ferroelectric character, with ferroelectric-paraelectric phase transition temperatures around 287-292 K that do not follow the Curie-Weiss law. The electrical measurements indicate that ac conductivities of the nanocomposites follow the Jonscher's universal power law, with activation energies of 0.42-0.63 eV based on Arrhenius-type behavior at high temperatures. The nanocomposites exhibit well-defined ferromagnetic hysteresis loops at room temperature (RT). The MD and ME measurements at RT indicate that BST/LSMO exhibits a nonlinear ME effect at low frequencies, with a threshold near 0.5 T. The magnetocapacitance (MCp) measurements evidence a quadratic dependence on magnetic field, further confirming the multiferroic nature of BST/LSMO. The order of MCp was found to be ˜7% per Tesla. The analysis of the MCp measurements indicates that one of the BST/LSMO compositions studied can be considered as a new multiferroic compound.

  14. 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)

  15. 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)

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Liquid phase in situ hydrodeoxygenation of biomass-derived phenolic compounds to hydrocarbons over bifunctional catalysts

    Science.gov (United States)

    Junfeng Feng; Chung-yun Hse; Zhongzhi Yang; Kui Wang; Jianchun Jiang; Junming Xu

    2017-01-01

    The objective of this study was to find an effective method for converting renewable biomass-derived phenolic compounds into hydrocarbons bio-fuel via in situ catalytic hydrodeoxygenation. The in situ hydrodeoxygenation of biomass-derived phenolic compounds was carried out in methanol-water solvent over bifunctional catalysts of Raney Ni and HZSM-5 or H-Beta. In the in...

  2. Bifunctional catalysts for the direct production of liquid fuels from syngas

    NARCIS (Netherlands)

    Sartipi, S.

    2014-01-01

    Design and development of catalyst formulations that maximize the direct production of liquid fuels by combining Fischer-Tropsch synthesis (FTS), hydrocarbon cracking, and isomerization into one single catalyst particle (bifunctional FTS catalyst) have been investigated in this thesis. To achieve

  3. Boosting Bifunctional Oxygen Electrocatalysis with 3D Graphene Aerogel-Supported Ni/MnO Particles.

    Science.gov (United States)

    Fu, Gengtao; Yan, Xiaoxiao; Chen, Yifan; Xu, Lin; Sun, Dongmei; Lee, Jong-Min; Tang, Yawen

    2018-02-01

    Electrocatalysts for oxygen-reduction and oxygen-evolution reactions (ORR and OER) are crucial for metal-air batteries, where more costly Pt- and Ir/Ru-based materials are the benchmark catalysts for ORR and OER, respectively. Herein, for the first time Ni is combined with MnO species, and a 3D porous graphene aerogel-supported Ni/MnO (Ni-MnO/rGO aerogel) bifunctional catalyst is prepared via a facile and scalable hydrogel route. The synthetic strategy depends on the formation of a graphene oxide (GO) crosslinked poly(vinyl alcohol) hydrogel that allows for the efficient capture of highly active Ni/MnO particles after pyrolysis. Remarkably, the resulting Ni-MnO/rGO aerogels exhibit superior bifunctional catalytic performance for both ORR and OER in an alkaline electrolyte, which can compete with the previously reported bifunctional electrocatalysts. The MnO mainly contributes to the high activity for the ORR, while metallic Ni is responsible for the excellent OER activity. Moreover, such bifunctional catalyst can endow the homemade Zn-air battery with better power density, specific capacity, and cycling stability than mixed Pt/C + RuO 2 catalysts, demonstrating its potential feasibility in practical application of rechargeable metal-air batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. High surface area carbon for bifunctional air electrodes applied in zinc-air batteries

    Energy Technology Data Exchange (ETDEWEB)

    Arai, H. [on leave from NTT Laboratories (Japan); Mueller, S.; Haas, O. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Bifunctional air electrodes with high surface area carbon substrates showed low reduction overpotential, thus are promising for enhancing the energy efficiency and power capability of zinc-air batteries. The improved performance is attributed to lower overpotential due to diffusion of the reaction intermediate, namely the peroxide ion. (author) 1 fig., 2 refs.

  5. D-bifunctional protein deficiency associated with drug resistant infantile spasms

    NARCIS (Netherlands)

    Buoni, Sabrina; Zannolli, Raffaella; Waterham, Hans; Wanders, Ronald; Fois, Alberto

    2007-01-01

    Peroxisomal disorders appear with a frequency of about 1:5000 in newborns. Peroxisomal D-bifunctional protein (D-BP), encoded by the HSD17B4 gene (gene ID: 3294; locus tag: HGNC:5213, chromosome 5q2; official symbol: HSD17B4; name: hydroxysteroid (17-beta) dehydrogenase; gene type: protein coding)

  6. Synthesis, characterization and use of ATRP bifunctional initiator with trichloromethyl end-groups

    Czech Academy of Sciences Publication Activity Database

    Toman, Luděk; Janata, Miroslav; Spěváček, Jiří; Masař, Bohumil; Vlček, Petr; Látalová, Petra

    2002-01-01

    Roč. 43, č. 2 (2002), s. 18-19 ISSN 0032-3934 R&D Projects: GA ČR GA203/01/0513 Institutional research plan: CEZ:AV0Z4050913 Keywords : bifunctional initiator * ATRP polymerization * trichloromethyl end-groups Subject RIV: CD - Macromolecular Chemistry

  7. Oxidations of amines with molecular oxygen using bifunctional gold–titania catalysts

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; Egeblad, Kresten; Mentzel, Uffe Vie

    2008-01-01

    Over the past decades it has become clear that supported gold nanoparticles are surprisingly active and selective catalysts for several green oxidation reactions of oxygen-containing hydrocarbons using molecular oxygen as the stoichiometric oxidant. We here report that bifunctional gold...

  8. Nanosheet Supported Single-Metal Atom Bifunctional Catalyst for Overall Water Splitting.

    Science.gov (United States)

    Ling, Chongyi; Shi, Li; Ouyang, Yixin; Zeng, Xiao Cheng; Wang, Jinlan

    2017-08-09

    Nanosheet supported single-atom catalysts (SACs) can make full use of metal atoms and yet entail high selectivity and activity, and bifunctional catalysts can enable higher performance while lowering the cost than two separate unifunctional catalysts. Supported single-atom bifunctional catalysts are therefore of great economic interest and scientific importance. Here, on the basis of first-principles computations, we report a design of the first single-atom bifunctional eletrocatalyst, namely, isolated nickel atom supported on β 12 boron monolayer (Ni 1 /β 12 -BM), to achieve overall water splitting. This nanosheet supported SAC exhibits remarkable electrocatalytic performance with the computed overpotential for oxygen/hydrogen evolution reaction being just 0.40/0.06 V. The ab initio molecular dynamics simulation shows that the SAC can survive up to 800 K elevated temperature, while enacting a high energy barrier of 1.68 eV to prevent isolated Ni atoms from clustering. A viable experimental route for the synthesis of Ni 1 /β 12 -BM SAC is demonstrated from computer simulation. The desired nanosheet supported single-atom bifunctional catalysts not only show great potential for achieving overall water splitting but also offer cost-effective opportunities for advancing clean energy technology.

  9. Synthesis, characterization and performance of bifunctional catalysts for the synthesis of menthol from citronellal

    NARCIS (Netherlands)

    ten Dam, J.; Ramanathan, A; Djanashvili, K.; Kapteijn, F.; Hanefeld, U.

    2017-01-01

    The synthesis of a series of bifunctional catalysts (1 wt% Pt/W-TUD-1 (Technische Universiteit Delft-1) and 1 wt% Pt/WO3/TUD-1) with different tungsten loadings (5-30 wt% WO3) is described. They were characterized using ICP-OES, INAA, N2 physisorption, XRD and

  10. Metagenomic Analysis of Apple Orchard Soil Reveals Antibiotic Resistance Genes Encoding Predicted Bifunctional Proteins▿

    Science.gov (United States)

    Donato, Justin J.; Moe, Luke A.; Converse, Brandon J.; Smart, Keith D.; Berklein, Flora C.; McManus, Patricia S.; Handelsman, Jo

    2010-01-01

    To gain insight into the diversity and origins of antibiotic resistance genes, we identified resistance genes in the soil in an apple orchard using functional metagenomics, which involves inserting large fragments of foreign DNA into Escherichia coli and assaying the resulting clones for expressed functions. Among 13 antibiotic-resistant clones, we found two genes that encode bifunctional proteins. One predicted bifunctional protein confers resistance to ceftazidime and contains a natural fusion between a predicted transcriptional regulator and a β-lactamase. Sequence analysis of the entire metagenomic clone encoding the predicted bifunctional β-lactamase revealed a gene potentially involved in chloramphenicol resistance as well as a predicted transposase. A second clone that encodes a predicted bifunctional protein confers resistance to kanamycin and contains an aminoglycoside acetyltransferase domain fused to a second acetyltransferase domain that, based on nucleotide sequence, was predicted not to be involved in antibiotic resistance. This is the first report of a transcriptional regulator fused to a β-lactamase and of an aminoglycoside acetyltransferase fused to an acetyltransferase not involved in antibiotic resistance. PMID:20453147

  11. Microwave assisted bi-functional activation of -bromo-tert-alcohols

    Indian Academy of Sciences (India)

    unsaturated ketones in good yield is reported. The reaction of substrates with DMSO in 1:1 ratio (w/v) is promoted by ZnS in a solvent-free condition. A concurrent bi-functional activation of trans-vicinal bromo- and hydroxyl groups with ZnS is ...

  12. Highly Enantioselective Three-Component Direct Mannich Reactions of Unfunctionalized Ketones Catalyzed by Bifunctional Organocatalysts

    Science.gov (United States)

    Guo, Qunsheng; Zhao, John Cong-Gui

    2013-01-01

    A highly stereoselective three-component direct Mannich reaction between aromatic aldehydes, p-toluenesulfonamide, and unfunctionalized ketones was achieved through an enolate mechanism for the first time with a bifunctional quinidine thiourea catalyst. The corresponding N-tosylated β-aminoketones were obtained in high yields and excellent diastereo- and enantioselectivities (up to >99:1 dr and >99% ee). PMID:23343472

  13. Direct catalytic transformation of carbohydrates into 5-ethoxymethylfurfural with acid–base bifunctional hybrid nanospheres

    International Nuclear Information System (INIS)

    Li, Hu; Govind, Khokarale Santosh; Kotni, Ramakrishna; Shunmugavel, Saravanamurugan; Riisager, Anders; Yang, Song

    2014-01-01

    Graphical abstract: Catalytic conversion of carbohydrates into HMF and EMF in ethanol/DMSO with acid–base bifunctional hybrid nanospheres prepared from self-assembly of corresponding basic amino acids and HPA. - Highlights: • Acid–base bifunctional nanospheres were efficient for production of EMF from sugars. • Synthesis of EMF in a high yield of 76.6% was realized from fructose. • Fructose based biopolymers could also be converted into EMF with good yields. • Ethyl glucopyranoside was produced in good yields from glucose in ethanol. - Abstract: A series of acid–base bifunctional hybrid nanospheres prepared from the self-assembly of basic amino acids and phosphotungstic acid (HPA) with different molar ratios were employed as efficient and recyclable catalysts for synthesis of liquid biofuel 5-ethoxymethylfurfural (EMF) from various carbohydrates. A high EMF yield of 76.6%, 58.5%, 42.4%, and 36.5% could be achieved, when fructose, inulin, sorbose, and sucrose were used as starting materials, respectively. Although, the acid–base bifunctional nanocatalysts were inert for synthesis of EMF from glucose based carbohydrates, ethyl glucopyranoside in good yields could be obtained from glucose in ethanol. Moreover, the nanocatalyst functionalized with acid and basic sites was able to be reused several times with no significant loss in catalytic activity

  14. Efficacy of a novel chelator BPCBG for removing uranium and protecting against uranium-induced renal cell damage in rats and HK-2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Yizhong; Wang, Dan [Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China); Li, Zhiming [Department of Chemistry, Fudan University, Shanghai 200433 (China); Hu, Yuxing; Xu, Aihong [Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China); Wang, Quanrui [Department of Chemistry, Fudan University, Shanghai 200433 (China); Shao, Chunlin [Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China); Chen, Honghong, E-mail: hhchen@shmu.edu.cn [Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China)

    2013-05-15

    Chelation therapy is a known effective method to increase the excretion of U(VI) from the body. Until now, no any uranium chelator has been approved for emergency medical use worldwide. The present study aimed to evaluate the efficacy of new ligand BPCBG containing two catechol groups and two aminocarboxylic acid groups in decorporation of U(VI) and protection against acute U(VI) nephrotoxicity in rats, and further explored the detoxification mechanism of BPCBG for U(VI)-induced nephrotoxicity in HK-2 cells with comparison to DTPA-CaNa{sub 3}. Chelating agents were administered at various times before or after injections of U(VI) in rats. The U(VI) levels in urine, kidneys and femurs were measured 24 h after U(VI) injections. Histopathological changes in the kidney and serum urea and creatinine and urine protein were examined. After treatment of U(VI)-exposed HK-2 cells with chelating agent, the intracellular U(VI) contents, formation of micronuclei, lactate dehydrogenase (LDH) activity and production of reactive oxygen species (ROS) were assessed. It was found that prompt, advanced or delayed injections of BPCBG effectively increased 24 h-urinary U(VI) excretion and decreased the levels of U(VI) in kidney and bone. Meanwhile, BPCBG injection obviously reduced the severity of the U(VI)-induced histological alterations in the kidney, which was in parallel with the amelioration noted in serum indicators, urea and creatinine, and urine protein of U(VI) nephrotoxicity. In U(VI)-exposed HK-2 cells, immediate and delayed treatment with BPCBG significantly decreased the formation of micronuclei and LDH release by inhibiting the cellular U(VI) intake, promoting the intracellular U(VI) release and inhibiting the production of intracellular ROS. Our data suggest that BPCBG is a novel bi-functional U(VI) decorporation agent with a better efficacy than DTPA-CaNa{sub 3}. - Highlights: ► BPCBG accelerated the urine U(VI) excretion and reduced the tissues U(VI) in rats.

  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. 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)

  17. 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

  18. 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.

  19. 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 ...

  20. 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)

  1. 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.

  2. 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.

  3. 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.

  4. 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 ...

  5. 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.

  6. 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.

  7. 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...

  8. 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 ...

  9. 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 ...

  10. 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.

  11. 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)

  12. A Metal-Amino Acid Complex-Derived Bifunctional Oxygen Electrocatalyst for Rechargeable Zinc-Air Batteries.

    Science.gov (United States)

    Ding, Yanjun; Niu, Yuchen; Yang, Jia; Ma, Liang; Liu, Jianguo; Xiong, Yujie; Xu, Hangxun

    2016-10-01

    Bifunctional oxygen electrocatalyst: A metal-amino acid complex is developed to prepare high-performance mesoporous carbon electrocatalyst for both oxygen reduction and oxygen evolution reactions. Such prepared catalyst can be used to assemble rechargeable zinc-air batteries with excellent durability. This work represents a new route toward low-cost, highly active, and durable bifunctional electrocatalysts for cutting-edge energy conversion devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 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.

  14. 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

  15. 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...

  16. 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.

  17. 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

  18. Bifunctional fluorescent probes for detection of amyloid aggregates and reactive oxygen species

    Science.gov (United States)

    Needham, Lisa-Maria; Weber, Judith; Fyfe, James W. B.; Kabia, Omaru M.; Do, Dung T.; Klimont, Ewa; Zhang, Yu; Rodrigues, Margarida; Dobson, Christopher M.; Ghandi, Sonia; Bohndiek, Sarah E.; Snaddon, Thomas N.; Lee, Steven F.

    2018-02-01

    Protein aggregation into amyloid deposits and oxidative stress are key features of many neurodegenerative disorders including Parkinson's and Alzheimer's disease. We report here the creation of four highly sensitive bifunctional fluorescent probes, capable of H2O2 and/or amyloid aggregate detection. These bifunctional sensors use a benzothiazole core for amyloid localization and boronic ester oxidation to specifically detect H2O2. We characterized the optical properties of these probes using both bulk fluorescence measurements and single-aggregate fluorescence imaging, and quantify changes in their fluorescence properties upon addition of amyloid aggregates of α-synuclein and pathophysiological H2O2 concentrations. Our results indicate these new probes will be useful to detect and monitor neurodegenerative disease.

  19. Sorption of Pu(IV) from nitric acid by bifunctional anion-exchange resins

    International Nuclear Information System (INIS)

    Bartsch, R.A.; Zhang, Z.Y.; Elshani, S.; Zhao, W.; Jarvinen, G.D.; Barr, M.E.; Marsh, S.F.; Chamberlin, R.M.

    1999-01-01

    Anion exchange is attractive for separating plutonium because the Pu(IV) nitrate complex is very strongly sorbed and few other metal ions form competing anionic nitrate complexes. The major disadvantage of this process has been the unusually slow rate at which the Pu(IV) nitrate complex is sorbed by the resin. The paper summarizes the concept of bifunctional anion-exchange resins, proposed mechanism for Pu(IV) sorption, synthesis of the alkylating agent, calculation of K d values from Pu(IV) sorption results, and conclusions from the study of Pu(IV) sorption from 7M nitric acid by macroporous anion-exchange resins including level of crosslinking, level of alkylation, length of spacer, and bifunctional vs. monofunctional anion-exchange resins

  20. First-Principles Study of Structure Property Relationships of Monolayer (Hydroxy)Oxide-Metal Bifunctional Electrocatalysts

    DEFF Research Database (Denmark)

    Zeng, Zhenhua; Kubal, Joseph; Greeley, Jeffrey Philip

    2015-01-01

    In the present study, on the basis of detailed density functional theory (DFT) calculations, and using Ni hydroxy(oxide) films on Pt(111) and Au(111) electrodes as model systems, we describe a detailed structural and electrocatalytic analysis of hydrogen evolution (HER) at three-phase boundaries...... of information that is inaccessible by purely experimental means, and these structures, in turn, strongly suggest that a bifunctional reaction mechanism for alkaline HER will be operative at the interface between the films, the metal substrates, and the surrounding aqueous medium. This bifunctionality produces...... important changes in the calculated barriers of key elementary reaction steps, including water activation and dissociation, as compared to traditional monofunctional Pt surfaces. The successful identification of the structures of thin metal films and three-phase boundary catalysts is not only an important...

  1. Preparations of bifunctional polymeric beads simultaneously incorporated with fluorescent quantum dots and magnetic nanocrystals

    International Nuclear Information System (INIS)

    Tu Chifeng; Yang Yunhua; Gao Mingyuan

    2008-01-01

    Bifunctional polystyrene beads simultaneously incorporated with fluorescent CdTe quantum dots (Q-dots) and superparamagnetic Fe 3 O 4 nanocrystals were prepared by a modified mini-emulsion polymerization method, in which polymerizable surfactants were used as both phase transfer agent for aqueous colloidal nanoparticles and emulsifier. In addition, silica coating was also introduced to Fe 3 O 4 nanocrystals for regulating the internal structure of the composite beads. Transmission electron microscopy, confocal fluorescence microscopy and conventional spectroscopy were used to characterize the composite beads, as well as the polymerizable surfactant-coated CdTe Q-dots and silica-coated Fe 3 O 4 nanoparticles. Different mixing methods were also attempted in order to vary the size of the resultant bifunctional beads

  2. First-Principles Study of Structure Property Relationships of Monolayer (Hydroxy)Oxide-Metal Bifunctional Electrocatalysts

    DEFF Research Database (Denmark)

    Zeng, Zhenhua; Kubal, Joseph; Greeley, Jeffrey Philip

    2015-01-01

    under alkaline electrochemical conditions. We demonstrate that the structure and oxidation state of the films can be systematically tuned by changing the applied electrode potential and/or the nature of substrates. Structural features determined from the theoretical calculations provide a wealth...... of information that is inaccessible by purely experimental means, and these structures, in turn, strongly suggest that a bifunctional reaction mechanism for alkaline HER will be operative at the interface between the films, the metal substrates, and the surrounding aqueous medium. This bifunctionality produces...... important changes in the calculated barriers of key elementary reaction steps, including water activation and dissociation, as compared to traditional monofunctional Pt surfaces. The successful identification of the structures of thin metal films and three-phase boundary catalysts is not only an important...

  3. Tethering metal ions to photocatalyst particulate surfaces by bifunctional molecular linkers for efficient hydrogen evolution

    KAUST Repository

    Yu, Weili

    2014-08-19

    A simple and versatile method for the preparation of photocatalyst particulates modified with effective cocatalysts is presented; the method involves the sequential soaking of photocatalyst particulates in solutions containing bifunctional organic linkers and metal ions. The modification of the particulate surfaces is a universal and reproducible method because the molecular linkers utilize strong covalent bonds, which in turn result in modified monolayer with a small but controlled quantity of metals. The photocatalysis results indicated that the CdS with likely photochemically reduced Pd and Ni, which were initially immobilized via ethanedithiol (EDT) as a linker, were highly efficient for photocatalytic hydrogen evolution from Na2S-Na2SO3-containing aqueous solutions. The method developed in this study opens a new synthesis route for the preparation of effective photocatalysts with various combinations of bifunctional linkers, metals, and photocatalyst particulate materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Direct catalytic transformation of carbohydrates into 5-ethoxymethylfurfural with acid–base bifunctional hybrid nanospheres

    DEFF Research Database (Denmark)

    Li, Hu; Khokarale, Santosh Govind; Kotni, Ramakrishna

    2014-01-01

    A series of acid–base bifunctional hybrid nanospheres prepared from the self-assembly of basic amino acids and phosphotungstic acid (HPA) with different molar ratios were employed as efficient and recyclable catalysts for synthesis of liquid biofuel 5-ethoxymethylfurfural (EMF) from various carbo...... glucopyranoside in good yields could be obtained from glucose in ethanol. Moreover, the nanocatalyst functionalized with acid and basic sites was able to be reused several times with no significant loss in catalytic activity...

  10. Radiation Induced Crosslinking of Polyethylene in the Presence of Bifunctional Vinyl Monomers

    DEFF Research Database (Denmark)

    Joshi, M. S.; Singer, Klaus Albert Julius; Silverman, J.

    1977-01-01

    Several reports have been published showing that the radiation induced grafting of bifunctional vinyl monomers to low density polyethylene results in a product with an unusually high density of crosslinks. The same grafting reactions are shown to reduce the incipient gel dose by more than a factor...... of fifty. This paper is concerned with the apparent crosslinking produced by the radiation grafting of two monomers to polyethylene: acrylic acid and acrylonitrile....

  11. 3D Ordered Mesoporous Bifunctional Oxygen Catalyst for Electrically Rechargeable Zinc-Air Batteries.

    Science.gov (United States)

    Park, Moon Gyu; Lee, Dong Un; Seo, Min Ho; Cano, Zachary Paul; Chen, Zhongwei

    2016-05-01

    To enhance energy efficiency and durability, a highly active and durable 3D ordered mesoporous cobalt oxide framework has been developed for rechargeable zinc-air batteries. The bifunctional air electrode consisting of 3DOM Co3 O4 having high active surface area and robust structure, results in superior charge and discharge battery voltages, and durable performance for electrically rechargeable zinc-air batteries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Bifunctional bridging linker-assisted synthesis and characterization of TiO{sub 2}/Au nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Žunič, Vojka, E-mail: vojka.zunic@ijs.si, E-mail: vojka13@gmail.com; Kurtjak, Mario; Suvorov, Danilo [Jožef Stefan Institute, Advanced Materials Department (Slovenia)

    2016-11-15

    Using a simple organic bifunctional bridging linker, titanium dioxide (TiO{sub 2}) nanoparticles were coupled with the Au nanoparticles to form TiO{sub 2}/Au nanocomposites with a variety of Au loadings. This organic bifunctional linker, meso-2,3-dimercaptosuccinic acid, contains two types of functional groups: (i) the carboxyl group, which enables binding to the TiO{sub 2}, and (ii) the thiol group, which enables binding to the Au. In addition, the organic bifunctional linker acts as a stabilizing agent to prevent the agglomeration and growth of the Au particles, resulting in the formation of highly dispersed Au nanoparticles. To form the TiO{sub 2}/Au nanocomposites in a simple way, we deliberately applied a synthetic method that simultaneously ensures: (i) the capping of the Au nanoparticles and (ii) the binding of different amounts of Au to the TiO{sub 2}. The TiO{sub 2}/Au nanocomposites formed with this method show enhanced UV and Vis photocatalytic activities when compared to the pure TiO{sub 2} nanopowders.Graphical Abstract.

  13. Bifunctional Perovskite Oxide Catalysts for Oxygen Reduction and Evolution in Alkaline Media.

    Science.gov (United States)

    Gupta, Shiva; Kellogg, William; Xu, Hui; Liu, Xien; Cho, Jaephil; Wu, Gang

    2016-01-01

    Oxygen electrocatalysis, namely of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), governs the performance of numerous electrochemical energy systems such as reversible fuel cells, metal-air batteries, and water electrolyzers. However, the sluggish kinetics of these two reactions and their dependency on expensive noble metal catalysts (e.g, Pt or Ir) prohibit the sustainable commercialization of these highly innovative and in-demand technologies. Bifunctional perovskite oxides have emerged as a new class of highly efficient non-precious metal catalysts (NPMC) for oxygen electrocatalysis in alkaline media. In this review, we discuss the state-of-the-art understanding of bifunctional properties of perovskites with regards to their OER/ORR activity in alkaline media and review the associated reaction mechanisms on the oxides surface and the related activity descriptors developed in the recent literature. We also summarize the present strategies to modify their electronic structure and to further improve their performance for the ORR/OER through highlighting the new concepts relating to the role of surface redox chemistry and oxygen deficiency of perovskite oxides for the ORR/OER activity. In addition, we provide a brief account of recently developed advanced perovskite-nanocarbon hybrid bifunctional catalysts with much improved performances. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Collagen/chitosan based two-compartment and bi-functional dermal scaffolds for skin regeneration

    International Nuclear Information System (INIS)

    Wang, Feng; Wang, Mingbo; She, Zhending; Fan, Kunwu; Xu, Cheng; Chu, Bin; Chen, Changsheng; Shi, Shengjun; Tan, Rongwei

    2015-01-01

    Inspired from the sophisticated bilayer structures of natural dermis, here, we reported collagen/chitosan based two-compartment and bi-functional dermal scaffolds. Two functions refer to mediating rapid angiogenesis based on recombinant human vascular endothelial growth factor (rhVEGF) and antibacterial from gentamicin, which were encapsulated in PLGA microspheres. The gentamicin and rhVEGF encapsulated PLGA microspheres were further combined with collagen/chitosan mixtures in low (lower layer) and high (upper layer) concentrations, and molded to generate the two-compartment and bi-functional scaffolds. Based on morphology and pore structure analyses, it was found that the scaffold has a distinct double layered porous and connective structure with PLGA microspheres encapsulated. Statistical analysis indicated that the pores in the upper layer and in the lower layer have great variations in diameter, indicative of a two-compartment structure. The release profiles of gentamicin and rhVEGF exceeded 28 and 49 days, respectively. In vitro culture of mouse fibroblasts showed that the scaffold can facilitate cell adhesion and proliferation. Moreover, the scaffold can obviously inhibit proliferation of Staphylococcus aureus and Serratia marcescens, exhibiting its unique antibacterial effect. The two-compartment and bi-functional dermal scaffolds can be a promising candidate for skin regeneration. - Highlights: • The dermal scaffold is inspired from the bilayer structures of natural dermis. • The dermal scaffold has two-compartment structures. • The dermal scaffold containing VEGF and gentamicin encapsulated PLGA microspheres • The dermal scaffold can facilitate cell adhesion and proliferation

  15. Development of Cobalt Hydroxide as a Bifunctional Catalyst for Oxygen Electrocatalysis in Alkaline Solution.

    Science.gov (United States)

    Zhan, Yi; Du, Guojun; Yang, Shiliu; Xu, Chaohe; Lu, Meihua; Liu, Zhaolin; Lee, Jim Yang

    2015-06-17

    Co(OH)2 in the form of hexagonal nanoplates synthesized by a simple hydrothermal reaction has shown even greater activity than cobalt oxides (CoO and Co3O4) in oxygen reduction and oxygen evolution reactions (ORR and OER) under alkaline conditions. The bifunctionality for oxygen electrocatalysis as shown by the OER-ORR potential difference (ΔE) could be reduced to as low as 0.87 V, comparable to the state-of-the-art non-noble bifunctional catalysts, when the Co(OH)2 nanoplates were compounded with nitrogen-doped reduced graphene oxide (N-rGO). The good performance was attributed to the nanosizing of Co(OH)2 and the synergistic interaction between Co(OH)2 and N-rGO. A zinc-air cell assembled with a Co(OH)2-air electrode also showed a performance comparable to that of the state-of-the-art zinc-air cells. The combination of bifunctional activity and operational stability establishes Co(OH)2 as an effective low-cost alternative to the platinum group metal catalysts.

  16. Collagen/chitosan based two-compartment and bi-functional dermal scaffolds for skin regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Feng [Department of Plastic Surgery and Burns, Shenzhen Second People' s Hospital, Shenzhen 518035 (China); Wang, Mingbo [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); She, Zhending [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Shenzhen Lando Biomaterials Co., Ltd., Shenzhen 518057 (China); Fan, Kunwu; Xu, Cheng [Department of Plastic Surgery and Burns, Shenzhen Second People' s Hospital, Shenzhen 518035 (China); Chu, Bin; Chen, Changsheng [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Shi, Shengjun, E-mail: shengjunshi@yahoo.com [The Burns Department of Zhujiang Hospital, Southern Medical University, Guangzhou 510280 (China); Tan, Rongwei, E-mail: tanrw@landobiom.com [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Shenzhen Lando Biomaterials Co., Ltd., Shenzhen 518057 (China)

    2015-07-01

    Inspired from the sophisticated bilayer structures of natural dermis, here, we reported collagen/chitosan based two-compartment and bi-functional dermal scaffolds. Two functions refer to mediating rapid angiogenesis based on recombinant human vascular endothelial growth factor (rhVEGF) and antibacterial from gentamicin, which were encapsulated in PLGA microspheres. The gentamicin and rhVEGF encapsulated PLGA microspheres were further combined with collagen/chitosan mixtures in low (lower layer) and high (upper layer) concentrations, and molded to generate the two-compartment and bi-functional scaffolds. Based on morphology and pore structure analyses, it was found that the scaffold has a distinct double layered porous and connective structure with PLGA microspheres encapsulated. Statistical analysis indicated that the pores in the upper layer and in the lower layer have great variations in diameter, indicative of a two-compartment structure. The release profiles of gentamicin and rhVEGF exceeded 28 and 49 days, respectively. In vitro culture of mouse fibroblasts showed that the scaffold can facilitate cell adhesion and proliferation. Moreover, the scaffold can obviously inhibit proliferation of Staphylococcus aureus and Serratia marcescens, exhibiting its unique antibacterial effect. The two-compartment and bi-functional dermal scaffolds can be a promising candidate for skin regeneration. - Highlights: • The dermal scaffold is inspired from the bilayer structures of natural dermis. • The dermal scaffold has two-compartment structures. • The dermal scaffold containing VEGF and gentamicin encapsulated PLGA microspheres • The dermal scaffold can facilitate cell adhesion and proliferation.

  17. 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...

  18. Preparation and characteristics of Fe3O4-YVO4:Eu3+ bifunctional magnetic-luminescent nanocomposites

    International Nuclear Information System (INIS)

    Peng Hongxia; Liu Guixia; Dong Xiangting; Wang Jinxian; Xu Jia; Yu Wensheng

    2011-01-01

    Graphical abstract: Highlights: → Bifunctional magnetic-luminescent nanocomposites with Fe 3 O 4 nanoparticles as the core and YVO 4 :Eu 3+ as the shell. → A cubic spinel structrue of Fe 3 O 4 core and a tetragonal phase of YVO 4 shell were obtained. → The nanocomposites displayed a strong red emission and superparamagnetic behavior at room temperature. - Abstract: A facile direct precipitation method has been developed for the synthesis of bifunctional magnetic-luminescent nanocomposites with Fe 3 O 4 nanoparticles as the core and YVO 4 :Eu 3+ as the shell. Transmission electron microscopy (TEM) images revealed that the obtained bifunctional nanocomposites had a core-shell structure and a spherical morphology. The average size was ∼150 nm, and the thickness of the shell was ∼15 nm. The X-ray diffraction (XRD) patterns showed that a cubic spinel structure of Fe 3 O 4 core and a tetragonal phase of YVO 4 shell were obtained. Fourier transform infrared (FT-IR) spectra confirmed that the YVO 4 :Eu 3+ had been successfully deposited on the surface of Fe 3 O 4 nanoparticles. Photoluminescence (PL) spectra indicated that the nanocomposites displayed a strong red characteristic emission of Eu 3+ . Magnetic measurements showed that the obtained bifunctional nanocomposites exhibited superparamagnetic behavior at room temperature. Therefore, the bifunctional nanocomposites are expected to develop many potential applications in biomedical fields.

  19. 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...

  20. 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...

  1. Unusual non-bifunctional mechanism for Co-PNP complex catalyzed transfer hydrogenation governed by the electronic configuration of metal center.

    Science.gov (United States)

    Hou, Cheng; Jiang, Jingxing; Li, Yinwu; Zhang, Zhihan; Zhao, Cunyuan; Ke, Zhuofeng

    2015-10-07

    The mimic of hydrogenases has unleashed a myriad of bifunctional catalysts, which are widely used in the catalytic hydrogenation of polar multiple bonds. With respect to ancillary ligands, the bifunctional mechanism is generally considered to proceed via the metal-ligand cooperation transition state. Inspired by the interesting study conducted by Hanson et al. (Chem Commun., 2013, 49, 10151), we present a computational study of a distinctive example, where a Co(II)-PNP catalyst with an ancillary ligand exhibits efficient transfer hydrogenation through a non-bifunctional mechanism. Both the bifunctional and non-bifunctional mechanisms are discussed. The calculated results, which are based on a full model of the catalyst, suggest that the inner-sphere non-bifunctional mechanism is more favorable (by ∼11 kcal mol(-1)) than the outer-sphere bifunctional mechanism, which is in agreement with the experimental observations. The origin of this mechanistic preference of the Co(II)-PNP catalyst can be attributed to its preference for the square planar geometry. A traditional bifunctional mechanism is less plausible for Co(II)-PNP due to the high distortion energy caused by the change in electronic configuration with the varied ligand field. Considering previous studies that focus on the development of ligands more often, this computational study indicates that the catalytic hydrogenation mechanism is controlled not only by the structure of the ligand but also by the electronic configuration of the metal center.

  2. 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.

  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. 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 .'

  5. Nanostructured Perovskite LaCo1-xMnxO3 as Bifunctional Catalysts for Rechargeable Metal-Air Batteries

    Science.gov (United States)

    Ge, Xiaoming; Li, Bing; Wuu, Delvin; Sumboja, Afriyanti; An, Tao; Hor, T. S. Andy; Zong, Yun; Liu, Zhaolin

    2015-09-01

    Bifunctional catalyst that is active for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the most important components of rechargeable metal-air batteries. Nanostructured perovskite bifunctional catalysts comprising La, Co and Mn(LaCo1-xMnxO3, LCMO) are synthesized by hydrothermal methods. The morphology, structure and electrochemical activity of the perovskite bifunctional catalysts are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and rotating disk electrode (RDE) techniques. Nanorod, nanodisc and nanoparticle are typical morphologies of LCMO. The electrocatalytic activity of LCMO is significantly improved by the addition of conductive materials such as carbon nanotube. To demonstrate the practical utilization, LCMO in the composition of LaCo0.8Mn0.2O3(LCMO82) is used as air cathode catalysts for rechargeable zinc-air batteries. The battery prototype can sustain 470 h or 40 discharge-charge cycles equivalent.

  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. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. [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.

  13. Further Characterization of the Bifunctional HIV Entry Inhibitor sCD4-FIT45

    Directory of Open Access Journals (Sweden)

    Alexander Falkenhagen

    2017-06-01

    Full Text Available HIV entry into target cells is a highly sequential and time-sensitive process. In recent years, potent HIV Env-targeting antibodies, such as VRC01, have been identified. However, antibodies bind only to a single epitope, and mutations that confer resistance to antibody-mediated inhibition of HIV entry have been detected. In contrast, HIV cannot escape from binding to soluble CD4 (sCD4 without a fitness disadvantage. sCD4 has the unique ability to induce conformational changes within the HIV envelope glycoproteins (Env that allow fusion inhibitors to bind. We have previously linked sCD4 to the fusion inhibitor FIT45 (sCD4-FIT45 and examined delivery of the bifunctional entry inhibitor via gene therapy. Here, we extend our studies and analyze the ability of sCD4-FIT45 to inhibit HIV Env-mediated cell fusion and HIV entry of several primary isolates. sCD4-FIT45 inhibited both cell fusion and HIV entry with remarkable antiviral activity. The mean 50% inhibitory concentrations (IC50 for sCD4-FIT45 were <0.2 μg/mL in both assays. Importantly, inhibition by sCD4-FIT45 was more potent than by VRC01, sCD4, or the previously described bifunctional protein sCD4-scFv17b. In contrast to sCD4, sCD4-FIT45 as well as VRC01 and sCD4-scFv17b did not mediate cell fusion between HIV Env+ and CD4−CCR5+ cells. The results presented here provide further evidence for the testing of sCD4-FIT45 and development of bifunctional proteins based on the sCD4-fusion inhibitor architecture.

  14. Further Characterization of the Bifunctional HIV Entry Inhibitor sCD4-FIT45.

    Science.gov (United States)

    Falkenhagen, Alexander; Joshi, Sadhna

    2017-06-16

    HIV entry into target cells is a highly sequential and time-sensitive process. In recent years, potent HIV Env-targeting antibodies, such as VRC01, have been identified. However, antibodies bind only to a single epitope, and mutations that confer resistance to antibody-mediated inhibition of HIV entry have been detected. In contrast, HIV cannot escape from binding to soluble CD4 (sCD4) without a fitness disadvantage. sCD4 has the unique ability to induce conformational changes within the HIV envelope glycoproteins (Env) that allow fusion inhibitors to bind. We have previously linked sCD4 to the fusion inhibitor FI T45 (sCD4-FI T45 ) and examined delivery of the bifunctional entry inhibitor via gene therapy. Here, we extend our studies and analyze the ability of sCD4-FI T45 to inhibit HIV Env-mediated cell fusion and HIV entry of several primary isolates. sCD4-FI T45 inhibited both cell fusion and HIV entry with remarkable antiviral activity. The mean 50% inhibitory concentrations (IC 50 ) for sCD4-FI T45 were <0.2 μg/mL in both assays. Importantly, inhibition by sCD4-FI T45 was more potent than by VRC01, sCD4, or the previously described bifunctional protein sCD4-scFv 17b . In contrast to sCD4, sCD4-FI T45 as well as VRC01 and sCD4-scFv 17b did not mediate cell fusion between HIV Env + and CD4 - CCR5 + cells. The results presented here provide further evidence for the testing of sCD4-FI T45 and development of bifunctional proteins based on the sCD4-fusion inhibitor architecture. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  15. Neurodegeneration in D-bifunctional protein deficiency: diagnostic clues and natural history using serial magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Aneal [University of Calgary, Department of Medical Genetics and Pediatrics, Alberta Children' s Hospital, Calgary, AB (Canada); Wei, Xing-Chang [University of Calgary, Department of Radiology, Alberta Children' s Hospital, Calgary, AB (Canada); Snyder, Floyd F. [Alberta Children' s Hospital, Biochemical Genetics Laboratory, Calgary, AB (Canada); Mah, Jean K. [University of Calgary, Division of Neurology, Department of Pediatrics, Calgary, AB (Canada); Waterham, Hans; Wanders, Ronald J.A. [University of Amsterdam, Academic Medical Center, Lab Genetic Metabolic Diseases, Amsterdam (Netherlands)

    2010-12-15

    We report serial neurodegenerative changes on neuroimaging in a rare peroxisomal disease called D-bifunctional protein deficiency. The pattern of posterior to anterior demyelination with white matter disease resembles X-linked adrenoleukodystrophy. We feel this case is important to (1) highlight that D-bifunctional protein deficiency should be considered in cases where the neuroimaging resembles X-linked adrenoleukodystrophy, (2) to show different stages of progression to help identify this disease using neuroimaging in children, and (3) to show that neuroimaging suggesting a leukodystrophy can warrant peroxisomal beta-oxidation studies in skin fibroblasts even when plasma very long chain fatty acids are normal. (orig.)

  16. Conversion of microalgal oil to biodiesel using bi-functional heterogenous catalysts MCS

    International Nuclear Information System (INIS)

    Nguyen Dang Toan; Nguyen Khanh Dieu Hong

    2015-01-01

    Biodiesel was synthesized from microalgal oil typed Botryococcus using a bi-functional heterogeneous catalyst mesoporous calcium containing silicate (MCS). The microalgal oil owned a very large amount of free fatty acid. The conditions for the reactions were controlled such as temperature, time, catalyst dosage, methanol/oil molar ratio and agitation speed. The results revealed that the optimum conditions should be temperature of 63 o C, reaction of 24 hours, catalyst dosage of 5 %wt, methanol/oil molar ratio of 45/1 and stirring speed of 450 rpm. The conversion of the reactions was 95.3 %. (author)

  17. Bifunctional groups grafted polyethersulfone magnetic beads for selective sequestration of plutonium

    International Nuclear Information System (INIS)

    Paul, Sumana; Aggarwal, S.K.; Pandey, A.K.

    2014-01-01

    The present study involves synthesis of polyethersulfone (PES) beads grafted with two different monomers viz. 2-hydroxyethylmethacrylate phosphoric acid ester (HEMP) and 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS) by photo-induced free radical polymerization method. The selection of bifunctional polymer was based on our previous studies, which indicated its efficacy for selective preconcentration of Pu from 3-4 mol L -1 HNO 3 . The HEMP-co-AMPS grafted PES beads were used for selective extraction of plutonium from dissolver solution

  18. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong

    2016-04-10

    tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  19. Basic evaluation of 67Ga labeled digoxin derivative as a metal-labeled bifunctional radiopharmaceutical

    International Nuclear Information System (INIS)

    Fujibayashi, Yasuhisa; Konishi, Junji; Takemura, Yasutaka; Taniuchi, Hideyuki; Iijima, Naoko; Yokoyama, Akira.

    1993-01-01

    To develop metal-labeled digoxin radiopharmaceuticals with affinity with anti-digoxin antibody as well as Na + , K + -ATPase, a digoxin derivative conjugated with deferoxamine was synthesized. The derivative had a high binding affinity with 67 Ga at deferoxamine introduced to the terminal sugar ring of digoxin. The 67 Ga labeled digoxin derivative showed enough in vitro binding affinity and selectivity to anti-digoxin antibody as well as Na + , K + -ATPase. The 67 Ga labeled digoxin derivative is considered to be a potential metal-labeled bifunctional radiopharmaceutical for digoxin RIA as well as myocardial Na + , K + -ATPase imaging. (author)

  20. Modifying the size and shape of monodisperse bifunctional alkaline-earth fluoride nanocrystals through lanthanide doping.

    Science.gov (United States)

    Chen, Daqin; Yu, Yunlong; Huang, Feng; Huang, Ping; Yang, Anping; Wang, Yuansheng

    2010-07-28

    In this communication, a simple route for modifying the uneven size and shape of alkaline-earth fluoride nanophases to monodisperse ultrasmall nanospheres through lanthanide doping is offered. These nanospheres are found to exhibit bifunctionality, i.e., tunable upconversion emissions as well as proper paramagnetism, making them potentially applicable in the biological field. The synthesis strategy, which involves doping of an impurity with a different valence than the cation in the nanophase, might be useful for controlling the solution growth of some technologically important nanomaterials.

  1. 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.

  2. 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.

  3. 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

  4. 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 ...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Orderly Layered Zr-Benzylphosphonate Nanohybrids for Efficient Acid-Base-Mediated Bifunctional/Cascade Catalysis.

    Science.gov (United States)

    Li, Hu; Fang, Zhen; He, Jian; Yang, Song

    2017-02-22

    The development of functional metal-organic materials that are robust and active for bifunctional/cascade catalysis is of great significance. Herein, a series of mesoporous and orderly layered nanohybrids were synthesized for the first time through simple and template-free assembly of ortho-, meta-, or para-xylylenediphosphonates (o-, p-, or m-PhP) containing zirconium. It was found that m-PhPZr nanoparticles (20-50 nm) with mesopores centered at 7.9 nm and high Lewis acid-base site ratio (1:0.7) showed excellent performance under mild conditions (as low as 82 °C) in transfer hydrogenation of carbonyl compounds, including bioaldehydes and alcohols, with near quantitative yields and little Zr leaching. Isotopic labeling studies indicated the occurrence of direct hydrogen transfer rather than metal hydride route by bifunctional catalysis. Lewis acidic (Zr) and basic (PO 3 ) centers of the heterogeneous catalyst were further revealed to play a synergistic role in one-pot cascade transformations, for example, of ethyl levulinate to γ-valerolactone and glucose to 5-hydroxymethylfurfural. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Conversion of cellulose into isosorbide over bifunctional ruthenium nanoparticles supported on niobium phosphate.

    Science.gov (United States)

    Sun, Peng; Long, Xiangdong; He, Hao; Xia, Chungu; Li, Fuwei

    2013-11-01

    Considerable effort has been applied to the development of new processes and catalysts for cellulose conversion to valuable platform chemicals. Isosorbide is among the most interesting products as it can be applied as a monomer and building block for the future replacement of fossil resource-based products. A sustainable method of isosorbide production from cellulose is presented in this work. The strategy relies on a bifunctional Ru catalyst supported on mesoporous niobium phosphate in a H2 atmosphere under pressure without further addition of any soluble acid. Over 50 % yield of isosorbide with almost 100 % cellulose conversion can be obtained in 1 h. The large surface area, pore size, and strong acidity of mesoporous niobium phosphate promote the hydrolysis of cellulose and dehydration of sorbitol; additionally, the appropriate size of the supported Ru nanoparticles avoids unnecessary hydrogenolysis of sorbitol. Under a cellulose/catalyst mass ratio of 43.3, the present bifunctional catalyst could be stably used up to six times, with its mesoporous structure well preserved and without detectable Ru leaching into the reaction solution. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Porous NiFe-Oxide Nanocubes as Bifunctional Electrocatalysts for Efficient Water-Splitting.

    Science.gov (United States)

    Kumar, Ashwani; Bhattacharyya, Sayan

    2017-12-06

    Electrocatalytic water-splitting, a combination of oxygen and hydrogen evolution reactions (OER and HER), is highly attractive in clean energy technologies, especially for high-purity hydrogen production, whereas developing stable, earth-abundant, bifunctional catalysts has continued to pose major challenges. Herein, a mesoporous NiFe-oxide nanocube (NiFe-NC) system is developed from a NiFe Prussian blue analog metal-organic framework as an efficient bifunctional catalyst for overall water-splitting. The NiFe-NCs with ∼200 nm side length have a Ni/Fe molar ratio of 3:2 and is a composite of NiO and α/γ-Fe 2 O 3 . The NCs demonstrate overpotentials of 271 and 197 mV for OER and HER, respectively, in 1 M KOH at 10 mA cm -2 , which outperform those of 339 and 347 mV for the spherical NiFe-oxide nanoparticles having a similar composition. The electrolyzer constructed using NiFe-NCs requires an impressive cell voltage of 1.67 V to deliver a current density of 10 mA cm -2 . Along with a mesoporous structure with a broad pore size distribution, the NiFe-NCs demonstrate the qualities of a desired corrosion-resistant water-splitting catalyst with long-term stability. The exposure of active sites at the edges and vertices of the NCs was validated to play a crucial role in their overall catalytic performance.

  18. Strongly Coupled Molybdenum Carbide on Carbon Sheets as a Bifunctional Electrocatalyst for Overall Water Splitting.

    Science.gov (United States)

    Wang, Hao; Cao, Yingjie; Sun, Cheng; Zou, Guifu; Huang, Jianwen; Kuai, Xiaoxiao; Zhao, Jianqing; Gao, Lijun

    2017-09-22

    High-performance and affordable electrocatalysts from earth-abundant elements are desirably pursued for water splitting involving hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Here, a bifunctional electrocatalyst of highly crystalline Mo 2 C nanoparticles supported on carbon sheets (Mo 2 C/CS) was designed toward overall water splitting. Owing to the highly active catalytic nature of Mo 2 C nanoparticles, the high surface area of carbon sheets and efficient charge transfer in the strongly coupled composite, the designed catalysts show excellent bifunctional behavior with an onset potential of -60 mV for HER and an overpotential of 320 mV to achieve a current density of 10 mA cm -2 for OER in 1 m KOH while maintaining robust stability. Moreover, the electrolysis cell using the catalyst only requires a low cell voltage of 1.73 V to achieve a current density of 10 mA cm -2 and maintains the activity for more than 100 h when employing the Mo 2 C/CS catalyst as both anode and cathode electrodes. Such high performance makes Mo 2 C/CS a promising electrocatalyst for practical hydrogen production from water splitting. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Proteolytic and partial sequencing studies of the bifunctional dihydrofolate reductase-thymidylate synthase from Daucus carota.

    Science.gov (United States)

    Cella, R; Carbonera, D; Orsi, R; Ferri, G; Iadarola, P

    1991-06-01

    The bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) of Daucus carota has been further characterized as regards molecular weight, amino acid composition, protease digestion and microsequencing of proteolytic peptides. Data reported in this paper demonstrate that the carrot protein has a calculated Mr of 124,000 thus indicating that, contrarily to what has previously been suggested, it occurs as a dimer of identical subunits. Results of partial amino acid microsequencing show the presence of sequences highly homologous with those of the active sites of both DHFR and TS from other organisms confirming, at the structural level, the bifunctional nature of the carrot protein. As in the case of Leishmania tropica DHFR-TS, incubation of the carrot protein with V8 protease led to a rapid loss of TS activity while retaining that of DHFR. However the pattern of proteolysis did not allow to establish whether the sequence of domains is DHFR-TS as in Leishmania, or vice versa. Low homology of other amino acid sequences, as judged by computer analysis, and absence of common epitopes indicate an apparent divergence between carrot and leishmanian proteins.

  20. Bifunctional metal-free catalysis of mesoporous noble carbons for oxygen reduction and evolution reactions.

    Science.gov (United States)

    Sakaushi, Ken; Fellinger, Tim-Patrick; Antonietti, Markus

    2015-04-13

    Electrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key reactions in lithium-oxygen batteries (LOBs) being a promising candidate to store renewable energies due to their high specific energy. However current development on LOBs is suffering from unsuitable catalysts. In particular, carbon-based catalysts were found to perform poorly in this system. Here, we show that metal-free mesoporous nitrogen-doped carbons (meso-NdCs) offer highly promising performances in both ORR and OER; they act as bifunctional catalysts, and can be synthesized by a very simple method. The efficient electrocatalytic activity of ORR and OER was used in a LOB cell during discharge and charge, respectively, and the present system showed a lower overpotential comparable to metal-based catalysts in LOB system. Thus, we demonstrate that meso-NdCs act as a new and affordable candidate for the efficient bifunctional oxygen catalysis, therefore can be applied to many energy-related applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Unprecedented Activity of Bifunctional Electrocatalyst for High Power Density Aqueous Zinc-Air Batteries.

    Science.gov (United States)

    Wang, Mengfan; Qian, Tao; Liu, Sisi; Zhou, Jinqiu; Yan, Chenglin

    2017-06-28

    The development of nonprecious metal catalysts with desirable bifunctional activities to supersede noble metal catalysts is of vital importance for high performance aqueous zinc-air batteries. Here, an unprecedented activity of bifunctional electrocatalyst is reported by in situ growth of nitrogen-enriched carbon nanotubes with transition metal composite. The resultant catalyst delivers surprisingly high OER (potential@10 mA cm -2 of 1.58 V) and ORR (onset potential of 0.97 V, half-wave potential of 0.86 V) performance. The overall oxygen electrode activity (overvoltage between ORR and OER) of the catalyst is as low as 0.72 V. In aqueous Zn-air battery tests, primary batteries demonstrate high maximum power density and two-electrode rechargeable batteries also exhibit good cycle performance. The unprecedented electrocatalyst opens up new avenues for developing highly active nitrogen-doped carbon nanotube-supported electrocatalysts and offers prospects for the next generation of fuel cells, metal-air batteries, and photocatalysis applications.

  2. Bifunctional silica nanospheres with 3-aminopropyl and phenyl groups. Synthesis approach and prospects of their applications

    Science.gov (United States)

    Kotsyuda, Sofiya S.; Tomina, Veronika V.; Zub, Yuriy L.; Furtat, Iryna M.; Lebed, Anastasia P.; Vaclavikova, Miroslava; Melnyk, Inna V.

    2017-10-01

    Spherical silica particles with bifunctional (tbnd Si(CH2)3NH2/tbnd SiC6H5) surface layers were synthesized by the Stöber method using ternary alkoxysilanes systems. The influence of the synthesis conditions, such as temperature and stirring time on the process of nanoparticles formation was studied. The presence of introduced functional groups was confirmed by FTIR. The composition of the surface layers examined by elemental analysis and acid-base titration was shown to be independent from the synthesis temperature. However, the size of the obtained particles depends on the synthesis temperature and, according to photon cross-correlation spectroscopy, can be varied from 50 to 846 nm. The variation of electric charges of N-functional groups was disclosed in obtained nanospheres and attributed to different surface location of these groups and their surrounding with other groups. The sorption of Cu(II) ions by functionalized silicas depends on the concentration of amino groups, which correlates with the isoelectric point values (determined to vary from 8.26 to 9.21). Bifunctional nanoparticles adsorb 99.0 mg/g of methylene blue, compared with 48.0 mg/g by silica sample with only amino groups. The nanospheres, both with and without adsorbed Cu2+, demonstrate reasonable antibacterial activity against S. aureus ATCC 25923, depending on particle concentration in water suspension.

  3. A bifunctional spin label reports the structural topology of phospholamban in magnetically-aligned bicelles

    Science.gov (United States)

    McCaffrey, Jesse E.; James, Zachary M.; Svensson, Bengt; Binder, Benjamin P.; Thomas, David D.

    2016-01-01

    We have applied a bifunctional spin label and EPR spectroscopy to determine membrane protein structural topology in magnetically-aligned bicelles, using monomeric phospholamban (PLB) as a model system. Bicelles are a powerful tool for studying membrane proteins by NMR and EPR spectroscopies, where magnetic alignment yields topological constraints by resolving the anisotropic spectral properties of nuclear and electron spins. However, EPR bicelle studies are often hindered by the rotational mobility of monofunctional Cys-linked spin labels, which obscures their orientation relative to the protein backbone. The rigid and stereospecific TOAC label provides high orientational sensitivity but must be introduced via solid-phase peptide synthesis, precluding its use in large proteins. Here we show that a bifunctional methanethiosulfonate spin label attaches rigidly and stereospecifically to Cys residues at i and i + 4 positions along PLB's transmembrane helix, thus providing orientational resolution similar to that of TOAC, while being applicable to larger membrane proteins for which synthesis is impractical. Computational modeling and comparison with NMR data shows that these EPR experiments provide accurate information about helix tilt relative to the membrane normal, thus establishing a robust method for determining structural topology in large membrane proteins with a substantial advantage in sensitivity over NMR.

  4. Synthesis and characterization of ZnS@Fe3O4 fluorescent-magnetic bifunctional nanospheres

    Science.gov (United States)

    Koc, Kenan; Karakus, Baris; Rajar, Kausar; Alveroglu, Esra

    2017-10-01

    Herein, we synthesized and characterized fluorescent and super paramagnetic ZnS@Fe3O4 nanospheres. First, (3-mercaptopropyl) trimethoxysilane (MPS) capped ZnS quantum dots (QDs) and SiO2 coated Fe3O4 nanoparticles were synthesized separately by using solution growth and co-precipitation techniques. After synthesis and characterization of these two nanoparticles, they were conglutinated together in a nano sized sphere. The QDs were attached to the surface of the Fe3O4 nanoparticles by Sisbnd Osbnd Si bonds and so Sisbnd Osbnd Si bonds created a SiO2 network around the nanoparticles during the formation of the ZnS@Fe3O4 nanospheres. The synthesized MPS capped ZnS fluorescent QDs, SiO2 coated magnetite super paramagnetic nanoparticles and ZnS@Fe3O4 fluorescent-magnetic bifunctional nanospheres were characterized by using UV-Vis Absorption Spectroscopy, Fluorescence Spectroscopy, X-ray analysis, Vibrating Sample Magnetometer analysis, Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy, Scanning Electron Microscope and Energy-dispersive X-ray spectroscopy. ZnS@Fe3O4 bifunctional nanospheres were shown to retain the magnetic properties of magnetite, while exhibiting the luminescent optical properties of ZnS nanoparticles. The combination of fluorescent and magnetic behaviors of nano composites make them useful for potential applications in the field of bio-medical and environmental.

  5. Cell Growth on ("Janus") Density Gradients of Bifunctional Zeolite L Crystals.

    Science.gov (United States)

    Kehr, Nermin Seda; Motealleh, Andisheh; Schäfer, Andreas H

    2016-12-28

    Nanoparticle density gradients on surfaces have attracted interest as two-dimensional material surfaces that can mimic the complex nano-/microstructure of the native extracellular matrix, including its chemical and physical gradients, and can therefore be used to systematically study cell-material interactions. In this respect, we report the preparation of density gradients made of bifunctional zeolite L crystals on glass surfaces and the effects of the density gradient and biopolymer functionalization of zeolite L crystals on cell adhesion. We also describe how we created "Janus" density gradient surfaces by gradually depositing two different types of zeolite L crystals that were functionalized and loaded with different chemical groups and guest molecules onto the two distinct sides of the same glass substrate. Our results show that more cells adhered on the density gradient of biopolymer-coated zeolites than on uncoated ones. The number of adhered cells increased up to a certain surface coverage of the glass by the zeolite L crystals, but then it decreased beyond the zeolite density at which a higher surface coverage decreased fibroblast cell adhesion and spreading. Additionally, cell experiments showed that cells gradually internalized the guest-molecule-loaded zeolite L crystals from the underlying density gradient containing bifunctional zeolite L crystals.

  6. Synthesis and characterization of new bifunctional nanocomposites possessing upconversion and oxygen-sensing properties

    International Nuclear Information System (INIS)

    Liu Lina; Li Bin; Qin Ruifei; Zhao Haifeng; Ren Xinguang; Su Zhongmin

    2010-01-01

    A new type of bifunctional nanocomposites for biomedical applications, upconversion NaY F 4 :Y b 3+ , Tm 3+ nanoparticles coated with Ru(II) complex chemically doped SiO 2 , has been developed by combining the useful functions of upconversion and oxygen-sensing properties into one nanoparticle. NaY F 4 :Y b 3+ , Tm 3+ nanoparticles were successfully coated with an Ru(II) complex doped SiO 2 shell with a thickness of ∼ 30 nm, and the surface of the SiO 2 was functionalized with amines. The obtained nanocomposites exhibited bright blue upconversion emission, and the luminescent emission intensity of the Ru(II) complex in the nanocomposites was sensitive to oxygen. Compared with the simple mixture of Ru(II) complex and SiO 2 , the core-shell nanocomposites showed better linearity between emission intensity of Ru(II) complex and oxygen concentrations. These bifunctional nanocomposites may find applications in biochemical and biomedical fields, such as biolabels and optical oxygen sensors, which can measure the oxygen concentrations in biological fluids.

  7. 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)

  8. 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.

  9. 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.

  10. 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.

  11. Iminodiacetic acid as bifunctional linker for dimerization of cyclic RGD peptides

    International Nuclear Information System (INIS)

    Xu, Dong; Zhao, Zuo-Quan; Chen, Shu-Ting; Yang, Yong; Fang, Wei; Liu, Shuang

    2017-01-01

    Introduction: In this study, I2P-RGD 2 was used as the example to illustrate a novel approach for dimerization of cyclic RGD peptides. The main objective of this study was to explore the impact of bifunctional linkers (glutamic acid vs. iminodiacetic acid) on tumor-targeting capability and excretion kinetics of the 99m Tc-labeled dimeric cyclic RGD peptides. Methods: HYNIC-I2P-RGD 2 was prepared by reacting I2P-RGD 2 with HYNIC-OSu in the presence of diisopropylethylamine, and was evaluated for its α v β 3 binding affinity against 125 I-echistatin bound to U87MG glioma cells. 99m Tc-I2P-RGD 2 was prepared with high specific activity (~185 GBq/μmol). The athymic nude mice bearing U87MG glioma xenografts were used to evaluate its biodistribution properties and image quality in comparison with those of 99m Tc-3P-RGD 2 . Results: The IC 50 value for HYNIC-I2P-RGD 2 was determined to be 39 ± 6 nM, which was very close to that (IC 50 = 33 ± 5 nM) of HYNIC-3P-RGD 2 . Replacing glutamic acid with iminodiacetic acid had little impact on α v β 3 binding affinity of cyclic RGD peptides. 99m Tc-I2P-RGD 2 and 99m Tc-3P-RGD 2 shared similar tumor uptake values over the 2 h period, and its α v β 3 -specificity was demonstrated by a blocking experiment. The uptake of 99m Tc-I2P-RGD 2 was significantly lower than 99m Tc-3P-RGD 2 in the liver and kidneys. The U87MG glioma tumors were visualized by SPECT with excellent contrast using both 99m Tc-I2P-RGD 2 and 99m Tc-3P-RGD 2 . Conclusion: Iminodiacetic acid is an excellent bifunctional linker for dimerization of cyclic RGD peptides. Bifunctional linkers have significant impact on the excretion kinetics of 99m Tc radiotracers. Because of its lower liver uptake and better tumor/liver ratios, 99m Tc-I2P-RGD 2 may have advantages over 99m Tc-3P-RGD 2 for diagnosis of tumors in chest region. -- Graphical abstract: This report presents novel approach for dimerization of cyclic RGD peptides using iminodiacetic acid as a

  12. Complexation and biodistribution study of 111In complexes of bifunctional phosphinic acid analogues of H4DOTA

    Czech Academy of Sciences Publication Activity Database

    Forsterová, Michaela; Zimová, Jana; Petrík, M.; Lázníček, M.; Lázníčková, A.; Hermann, P.; Melichar, František

    2007-01-01

    Roč. 2, č. 337 (2007), s. 34-34 ISSN 1619-7070 R&D Projects: GA AV ČR 1QS100480501 Institutional research plan: CEZ:AV0Z10480505 Keywords : bifunctional H4DOTA ligands * phosphinic acid analogues, * complexation of 111In Subject RIV: FR - Pharmacology ; Medidal Chemistry

  13. Opportunities and challenges in the electrocatalysis of CO2 and CO reduction using bifunctional surfaces

    DEFF Research Database (Denmark)

    Jovanov, Zarko; Hansen, Heine A.; Varela Gasque, Ana Sofia

    2016-01-01

    "bifunctional" catalysts using Au-Cd based alloys inspired by theoretical modelling. Density functional theory calculations suggest more favourable thermodynamics for CO2 reduction to CO and methanol on mixed Au-Cd sites on Au3Cd relative to similar values on Au. We use various tools to test the bulk...

  14. Production of medium-chain, a, omega-bifunctional monomers from fatty acids and n-alkanes

    NARCIS (Netherlands)

    Nuland, Youri M.

    2017-01-01

    In chapter 1, we give an introduction to bifunctional monomers that play an important role in the chemical industry. Briefly, the conventional production processes of α,ω-dicarboxylic acids and α,ω-diols are discussed. Strategies for more sustainable

  15. A bifunctional curcumin analogue for two-photon imaging and inhibiting crosslinking of amyloid beta in Alzheimer's disease.

    Science.gov (United States)

    Zhang, Xueli; Tian, Yanli; Yuan, Peng; Li, Yuyan; Yaseen, Mohammad A; Grutzendler, Jaime; Moore, Anna; Ran, Chongzhao

    2014-10-09

    In this report, we designed a highly bright bifunctional curcumin analogue CRANAD-28. In vivo two-photon imaging suggested that CRANAD-28 could penetrate the blood brain barrier (BBB) and label plaques and cerebral amyloid angiopathies (CAAs). We also demonstrated that this imaging probe could inhibit the crosslinking of amyloid beta induced either by copper or by natural conditions.

  16. Catalysis engineering of bifunctional solids for the one-step synthesis of liquid fuels from syngas : A review

    NARCIS (Netherlands)

    Sartipi, S.; Makkee, M.; Kapteijn, F.; Gascon, J.

    2014-01-01

    The combination of acidic zeolites and Fischer–Tropsch synthesis (FTS) catalysts for one-step production of liquid fuels from syngas is critically reviewed. Bifunctional systems are classified by the proximity between FTS and acid functionalities on three levels: reactor, catalyst particle, and

  17. Typical cMRI Pattern as Diagnostic Clue for D-Bifunctional Protein Deficiency Without Apparent Biochemical Abnormalities in Plasma

    NARCIS (Netherlands)

    Grønborg, Sabine; Krätzner, Ralph; Spiegler, Juliane; Ferdinandusse, Sacha; Wanders, Ronald J. A.; Waterham, Hans R.; Gärtner, Jutta

    2010-01-01

    D-bifunctional protein deficiency (DBPD) is an autosomal recessive disease caused by a defect in peroxisomal beta-oxidation. The majority of patients suffer from a severe neurological disease with neonatal hypotonia and seizures and die within the first 2 years of life. Few patients show milder

  18. Bifunctional ferrocene-based squaramide-phosphine as an organocatalyst for highly enantioselective intramolecular Morita-Baylis-Hillman reaction.

    Science.gov (United States)

    Zhang, Xiaorui; Ma, Pengfei; Zhang, Dongxu; Lei, Yang; Zhang, Shengyong; Jiang, Ru; Chen, Weiping

    2014-04-21

    This work demonstrates that, in accord with metal catalysis, ferrocene could be an excellent scaffold for organocatalysts. The simple and easily accessible bifunctional ferrocene-based squaramide-phosphine shows high enantioselectivity in the intramolecular Morita-Baylis-Hillman reaction of 7-aryl-7-oxo-5-heptenals, giving a variety of 2-aroyl-2-cyclohexenols in up to 96% ee.

  19. Facile synthesis of 4-vinyl- and 4-fluorovinyl-1,2,3-triazoles via bifunctional “click-olefination” reagents

    Science.gov (United States)

    Kumar, Rakesh; Pradhan, Padmanava; Zajc, Barbara

    2011-01-01

    Modular synthesis of vinyl and fluorovinyl triazoles can be achieved from bifunctional propargyl and fluoropropargyl sulfones by Cu-catalyzed azide-alkyne ligation and Julia-Kocienski olefination. Competitive click reactions of the protio and fluoropropargyl sulfones show higher reactivity of the latter, and a preliminary DFT analysis was performed. PMID:21336351

  20. Asymmetric additions of thioglycolates and N-Boc aldimines catalyzed by a bifunctional tertiary-amine squaramide.

    Science.gov (United States)

    Feng, Bo-Xu; Wang, Bin; Li, Xin

    2016-10-21

    A highly enantioselective asymmetric addition reaction of thioglycolates and N-Boc aldimines was promoted by a bifunctional tertiary-amine squaramide catalyst. As a result, a number of chiral N,S-acetal derivatives were efficiently synthesized with good enantioselectivities.

  1. Bifunctional ferromagnetic Eu-Gd-Bi-codoped hybrid organo-silica red emitting phosphors synthesized by a modified Pechini sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Abo-Naf, S.M., E-mail: sm.abo-naf@nrc.sci.eg [Glass Research Department, National Research Centre (NRC), El-Buhouth Str., Dokki, 12622 Cairo (Egypt); Abdel-Hameed, S.A.M.; Marzouk, M.A. [Glass Research Department, National Research Centre (NRC), El-Buhouth Str., Dokki, 12622 Cairo (Egypt); Hamdy, Y.M. [Spectroscopy Department, National Research Centre (NRC), El-Buhouth Str., Dokki, 12622 Cairo (Egypt)

    2017-06-15

    Red phosphor, composed of Eu-Gd-Bi-codoped hybrid organo-silica glass, has been synthesized via a modified Pechini sol-gel process. The synthesized hybrid glass was analyzed with powder X-ray diffraction (XRD), differential thermal analysis coupled with thermogravimetry (DTA-TG) and Fourier transform infrared (FTIR) spectroscopy. XRD and DTA-TG confirmed its amorphous structure up to 1000 °C. Magnetic behavior of the produced phosphor was investigated using vibrating specimen magnetometer (VSM) and the obtained results revealed its unsaturated ferromagnetic behavior. Photoluminescence (PL) properties of the obtained phosphor have been investigated under near-UV excitation at 395 nm. The influence of calcination temperature on the PL intensity and its decay behavior as well as on the ferromagnetic characteristics has been studied to determine the optimal reaction temperature of the phosphor. The PL emission spectra show the characteristic emission bands of Eu{sup 3+} ions in the wavelength range from 580 to 700 nm. These emission spectra have been dominated by the electric dipole {sup 5}D{sub 0}→{sup 7}F{sub 2} transition of the Eu{sup 3+} peaked at 610–620 nm producing the red light emission of the phosphors. It was found that the phosphor performance, expressed by its PL intensity and life time, could be significantly improved by increasing of the heat treatment temperature up to 900 °C. Also, calcination at 900 °C for 6 h greatly increased both of the magnetization and retentivity, while decreased the coercivity value. The organic phenomenon of metal citrate-ethylene glycol chelation and its degradation by calcination were well followed by FTIR spectroscopy. The obtained results are promising and could afford a basis for designing of efficient red phosphors for displays, lighting and bifunctional biosensors for biomedical applications. - Highlights: • Eu-Gd-Bi-codoped hybrid organo-silica phosphor was synthesized by sol-gel method. • Inorganic Eu

  2. 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

  3. 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)

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

    Science.gov (United States)

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

    2016-02-01

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

  5. 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.

  6. The structure of Haemophilus influenzae prephenate dehydrogenase suggests unique features of bifunctional TyrA enzymes

    International Nuclear Information System (INIS)

    Chiu, Hsiu-Ju; Abdubek, Polat; Astakhova, Tamara; Axelrod, Herbert L.; Carlton, Dennis; Clayton, Thomas; Das, Debanu; Deller, Marc C.; Duan, Lian; Feuerhelm, Julie; Grant, Joanna C.; Grzechnik, Anna; 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; Miller, Mitchell D.; Morse, Andrew T.; Nigoghossian, Edward; Okach, Linda; Reyes, Ron; Tien, Henry J.; Trame, Christine B.; 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 prephenate dehydrogenase component of the bifunctional H. influenzae TyrA reveals unique structural differences between bifunctional and monofunctional TyrA enzymes. Chorismate mutase/prephenate dehydrogenase from Haemophilus influenzae Rd KW20 is a bifunctional enzyme that catalyzes the rearrangement of chorismate to prephenate and the NAD(P) + -dependent oxidative decarboxylation of prephenate to 4-hydroxyphenylpyruvate in tyrosine biosynthesis. The crystal structure of the prephenate dehydrogenase component (HinfPDH) of the TyrA protein from H. influenzae Rd KW20 in complex with the inhibitor tyrosine and cofactor NAD + has been determined to 2.0 Å resolution. HinfPDH is a dimeric enzyme, with each monomer consisting of an N-terminal α/β dinucleotide-binding domain and a C-terminal α-helical dimerization domain. The structure reveals key active-site residues at the domain interface, including His200, Arg297 and Ser179 that are involved in catalysis and/or ligand binding and are highly conserved in TyrA proteins from all three kingdoms of life. Tyrosine is bound directly at the catalytic site, suggesting that it is a competitive inhibitor of HinfPDH. Comparisons with its structural homologues reveal important differences around the active site, including the absence of an α–β motif in HinfPDH that is present in other TyrA proteins, such as Synechocystis sp. arogenate dehydrogenase. Residues from this motif are involved in discrimination between NADP + and NAD + . The loop between β5 and β6 in the N-terminal domain is much shorter in HinfPDH and an extra helix is present at the C-terminus. Furthermore, HinfPDH adopts a more closed conformation compared with TyrA proteins that do not have tyrosine bound. This conformational change brings the substrate, cofactor and active-site residues into close proximity for catalysis. An ionic network consisting of Arg297 (a key residue for tyrosine binding), a water molecule, Asp206 (from

  7. Oxygen electrode bifunctional electrocatalyst NiCo2O4 spinel

    Science.gov (United States)

    Fielder, William L.; Singer, Joseph

    1988-01-01

    A significant increase in energy density may be possible if a two-unit alkaline regenerative H2-O2 fuel cell is replaced with a single-unit system that uses passive means for H2O transfer and thermal control. For this single-unit system, new electrocatalysts for the O2 electrode will be required which are not only bifunctionally active but also chemically and electrochemically stable between the voltage range of about 0.7 and 1.5 V. NiCo2O4 spinel is reported to have certain characteristics that make it useful for a study of electrode fabrication techniques. High surface area NiCo2O4 powder was fabricated into unsupported, bifunctional, PTFE-bonded, porous gas fuel cell electrodes by commercial sources using varying PTFE contents and sintering temperatures. The object of this study is to measure the bifunctional activities of these electrodes and to observe what performance differences might result from different commercial electrode fabricators. O2 evolution and O2 reduction data were obtained at 80 C (31 percent KOH). An irreversible reaction (i.e., aging) occurred during O2 evolution at potentials greater than about 1.5 V. Anodic Tafel slopes of 0.06 and 0.12 V/decade were obtained for the aged electrodes. Within the range of 15 to 25 percent, the PTFE content was not a critical parameter for optimizing the electrode for O2 evolution activity. Sintering temperatures between 300 and 340 C may be adequate but heating at 275 C may not be sufficient to properly sinter the PTFE-NiCo2O4 mixture. Electrode disintegration was observed during O2 reduction. Transport of O2 to the NiCo2O4 surface became prohibitive at greater than about -0.02 A/sq cm. Cathodic Tafel slopes of -0.6 and -0.12 V/decade were assumed for the O2 reduction process. A PTFE content of 25 percent (or greater) appears to be preferable for sintering the PTFE-NiCo2O4 mixture.

  8. 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

  9. 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...

  10. 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.

  11. 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)

  12. Eggplant-derived microporous carbon sheets: towards mass production of efficient bifunctional oxygen electrocatalysts at low cost for rechargeable Zn-air batteries.

    Science.gov (United States)

    Li, Bing; Geng, Dongsheng; Lee, Xinjing Shannon; Ge, Xiaoming; Chai, Jianwei; Wang, Zhijuan; Zhang, Jie; Liu, Zhaolin; Hor, T S Andy; Zong, Yun

    2015-05-25

    We report 2D microporous carbon sheets with high surface area, derived from eggplant via simple carbonization and KOH activation, as low cost yet efficient bifunctional catalysts for high performance rechargeable zinc-air batteries.

  13. 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.

  14. Synthesis of acrylic and allylic bifunctional cross-linking monomers derived from PET waste

    International Nuclear Information System (INIS)

    Cruz-Aguilar, A; Herrera-González, A M; Vázquez-García, R A; Coreño, J; Navarro-Rodríguez, D

    2013-01-01

    An acrylic and two novel allylic monomers synthesized from bis (hydroxyethyl) terephthalate, BHET, are reported. This was obtained by glycolysis of post-consumer PET with boiling ethylene glycol. The bifunctional monomer bis(2-(acryloyloxy)ethyl) terephthalate was obtained from acryloyl chloride, while the allylic monomers 2-(((allyloxi)carbonyl)oxy) ethyl (2-hydroxyethyl) terephthalate and bis(2-(((allyloxi)carbonyl)oxy)ethyl) terephthalate, from allyl chloroformate. Cross-linking was studied in bulk polymerization using two different thermal initiators. Monomers were analyzed by means of 1 H NMR and the cross-linked polymers by infrared spectroscopy. Gel content higher than 90% was obtained for the acrylic monomer. In the case of the mixture of the allylic monomers, the cross-linked polymer was 80 % using BPO initiator, being this mixture 24 times less reactive than the acrylic monomer.

  15. Crystal structure of human leukotriene A(4) hydrolase, a bifunctional enzyme in inflammation.

    Science.gov (United States)

    Thunnissen, M M; Nordlund, P; Haeggström, J Z

    2001-02-01

    Leukotriene (LT) A(4) hydrolase/aminopeptidase (LTA4H) is a bifunctional zinc enzyme that catalyzes the biosynthesis of LTB4, a potent lipid chemoattractant involved in inflammation, immune responses, host defense against infection, and PAF-induced shock. The high resolution crystal structure of LTA4H in complex with the competitive inhibitor bestatin reveals a protein folded into three domains that together create a deep cleft harboring the catalytic Zn(2+) site. A bent and narrow pocket, shaped to accommodate the substrate LTA(4), constitutes a highly confined binding region that can be targeted in the design of specific anti-inflammatory agents. Moreover, the structure of the catalytic domain is very similar to that of thermolysin and provides detailed insight into mechanisms of catalysis, in particular the chemical strategy for the unique epoxide hydrolase reaction that generates LTB(4).

  16. Dyes as bifunctional markers of DNA hybridization on surfaces and mutation detection.

    Science.gov (United States)

    García-Mendiola, Tania; Cerro, María Ramos; López-Moreno, José María; Pariente, Félix; Lorenzo, Encarnación

    2016-10-01

    The interaction of small molecules with DNA has found diagnostic and therapeutic applications. In this work, we propose the use of two different dyes, in particular Azure A and Safranine, as bifunctional markers of on-surface DNA hybridization and potent tools for screening of specific gene mutations directly in real DNA PCR amplicons extracted from blood cells. By combining spectroscopic and electrochemical methods we demonstrate that both dyes can interact with single and double stranded DNA to a different extent, allowing reliable hybridization detection. From these data, we have also elucidated the nature of the interaction. We conclude that the binding mode is fundamentally intercalative with an electrostatic component. The dye fluorescence allows their use as nucleic acid stains for the detection of on-surfaces DNA hybridization. Its redox activity is exploited in the development of selective electrochemical DNA biosensors. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. New Tailor-Made Alkyl-Aldehyde Bifunctional Supports for Lipase Immobilization

    Directory of Open Access Journals (Sweden)

    Robson Carlos Alnoch

    2016-11-01

    Full Text Available Immobilized and stabilized lipases are important biocatalytic tools. In this paper, different tailor-made bifunctional supports were prepared for the immobilization of a new metagenomic lipase (LipC12. The new supports contained hydrophobic groups (different alkyl groups to promote interfacial adsorption of the lipase and aldehyde groups to react covalently with the amino groups of side chains of the adsorbed lipase. The best catalyst was 3.5-fold more active and 5000-fold more stable than the soluble enzyme. It was successfully used in the regioselective deacetylation of peracetylated d-glucal. The PEGylated immobilized lipase showed high regioselectivity, producing high yields of the C-3 monodeacetylated product at pH 5.0 and 4 °C.

  18. Synthesis of Bifunctional Azobenzene Glycoconjugates for Cysteine-Based Photosensitive Cross-Linking with Bioactive Peptides.

    Science.gov (United States)

    Müller, Anne; Kobarg, Hauke; Chandrasekaran, Vijayanand; Gronow, Joana; Sönnichsen, Frank D; Lindhorst, Thisbe K

    2015-09-21

    Azobenzene linker molecules can be utilized to control peptide/protein function when they are ligated to appropriately spaced amino acid side chains of the peptide. This is because the photochemical E/Z isomerization of the azobenzene N=N double bond allows to switch peptide conformation between folded and unfolded. In this context, we have introduced carbohydrate-functionalized azobenzene derivatives in order to advance the biocompatible properties of azobenzene peptide linkers. Chloroacetamide-functionalized and O-allylated carbohydrate derivatives were synthesized and conjugated with azobenzene to achieve new bifunctional cross-linkers, in order to allow ligation to cysteine side chains by nucleophilic substitution or thiol-ene reaction, respectively. The photochromic properties of the new linker glycoconjugates were determined and first ligation reactions performed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Bioinspired design of a hybrid bifunctional enzymatic/organic electrocatalyst for site selective alcohol oxidation.

    Science.gov (United States)

    Lancaster, Louis; Hickey, David P; Sigman, Matthew S; Minteer, Shelley D; Wheeldon, Ian

    2018-01-11

    This work combines the thermostable alcohol dehydrogenase D (AdhD) from Pyrococcus furiosus and the organic electrocatalyst TEMPO to create a bifunctional catalyst that selectively oxidizes primary and secondary alcohols. The active sites function independently, can be switched on by changing reaction conditions, and can selectively oxidize a mixture of 1- and 2-butanol. The NAD + -dependent enzyme catalyses the secondary alcohol oxidation at a rate 3-fold faster than the primary alcohol, while the covalently attached 4-glycidyl-TEMPO oxidizes 1-butanol and has negligible activity toward 2-butanol. This hybrid catalytic approach has potential value for selective alcohol oxidations as well as other electrochemical and enzymatic multistep processes in energy conversion and chemical synthesis.

  20. Bifunctional Hydrogels Containing the Laminin Motif IKVAV Promote Neurogenesis

    Directory of Open Access Journals (Sweden)

    Aleeza Farrukh

    2017-11-01

    Full Text Available Engineering of biomaterials with specific biological properties has gained momentum as a means to control stem cell behavior. Here, we address the effect of bifunctionalized hydrogels comprising polylysine (PL and a 19-mer peptide containing the laminin motif IKVAV (IKVAV on embryonic and adult neuronal progenitor cells under different stiffness regimes. Neuronal differentiation of embryonic and adult neural progenitors was accelerated by adjusting the gel stiffness to 2 kPa and 20 kPa, respectively. While gels containing IKVAV or PL alone failed to support long-term cell adhesion, in bifunctional gels, IKVAV synergized with PL to promote differentiation and formation of focal adhesions containing β1-integrin in embryonic cortical neurons. Furthermore, in adult neural stem cell culture, bifunctionalized gels promoted neurogenesis via the expansion of neurogenic clones. These data highlight the potential of synthetic matrices to steer stem and progenitor cell behavior via defined mechano-adhesive properties.

  1. Boehmite-An Efficient and Recyclable Acid-Base Bifunctional Catalyst for Aldol Condensation Reaction.

    Science.gov (United States)

    Reshma, P C Rajan; Vikneshvaran, Sekar; Velmathi, Sivan

    2018-06-01

    In this work boehmite was used as an acid-base bifunctional catalyst for aldol condensation reactions of aromatic aldehydes and ketones. The catalyst was prepared by simple sol-gel method using Al(NO3)3·9H2O and NH4OH as precursors. The catalyst has been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), UV-visible spectroscopy (DRS), BET surface area analyses. Boehmite is successfully applied as catalyst for the condensation reaction between 4-nitrobenzaldehyde and acetone as a model substrate giving α, β-unsaturated ketones without any side product. The scope of the reaction is extended for various substituted aldehydes. A probable mechanism has been suggested to explain the cooperative behavior of the acidic and basic sites. The catalyst is environmentally friendly and easily recovered from the reaction mixture. Also the catalyst is reusable up to 3 catalytic cycles.

  2. Development of tartaric esters as bifunctional additives of methanol-gasoline.

    Science.gov (United States)

    Zhang, Jie; Yang, Changchun; Tang, Ying; Zhou, Rui; Wang, Xiaoli; Xu, Lianghong

    2014-01-01

    Methanol has become an alternative fuel for gasoline, which is facing a rapidly rising world demand with a limited oil supply. Methanol-gasoline has been used in China, but phase stability and vapor lock still need to be resolved in methanol-gasoline applications. In this paper, a series of tartaric esters were synthesized and used as phase stabilizers and saturation vapor pressure depressors for methanol-gasoline. The results showed that the phase stabilities of tartaric esters for methanol-gasoline depend on the length of the alkoxy group. Several tartaric esters were found to be effective in various gasoline-methanol blends, and the tartaric esters display high capacity to depress the saturation vapor pressure of methanol-gasoline. According to the results, it can be concluded that the tartaric esters have great potential to be bifunctional gasoline-methanol additives.

  3. Bi-functional biobased packing of the cassava starch, glycerol, licuri nanocellulose and red propolis.

    Directory of Open Access Journals (Sweden)

    Samantha Serra Costa

    Full Text Available The aim of this study was to characterize and determine the bi-functional efficacy of active packaging films produced with starch (4% and glycerol (1.0%, reinforced with cellulose nanocrystals (0-1% and activated with alcoholic extracts of red propolis (0.4 to 1.0%. The cellulose nanocrystals used in this study were extracted from licuri leaves. The films were characterized using moisture, water-activity analyses and water vapor-permeability tests and were tested regarding their total phenolic compounds and mechanical properties. The antimicrobial and antioxidant efficacy of the films were evaluated by monitoring the use of the active films for packaging cheese curds and butter, respectively. The cellulose nanocrystals increased the mechanical strength of the films and reduced the water permeability and water activity. The active film had an antimicrobial effect on coagulase-positive staphylococci in cheese curds and reduced the oxidation of butter during storage.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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

  11. Dimerization and Bifunctionality Confer Robustness to the Isocitrate Dehydrogenase Regulatory System in Escherichia coli*

    Science.gov (United States)

    Dexter, Joseph P.; Gunawardena, Jeremy

    2013-01-01

    An important goal of systems biology is to develop quantitative models that explain how specific molecular features give rise to systems-level properties. Metabolic and regulatory pathways that contain multifunctional proteins are especially interesting to study from this perspective because they have frequently been observed to exhibit robustness: the ability for a system to perform its proper function even as levels of its components change. In this study, we use extensive biochemical data and algebraic modeling to develop and analyze a model that shows how robust behavior arises in the isocitrate dehydrogenase (IDH) regulatory system of Escherichia coli, which was shown in 1985 to experimentally exhibit robustness. E. coli IDH is regulated by reversible phosphorylation catalyzed by the bifunctional isocitrate dehydrogenase kinase/phosphatase (IDHKP), and the level of IDH activity determines whether carbon flux is directed through the glyoxylate bypass (for growth on two-carbon substrates) or the full tricarboxylic acid cycle. Our model, which incorporates recent structural data on IDHKP, identifies several specific biochemical features of the system (including homodimerization of IDH and bifunctionality of IDHKP) that provide a potential explanation for robustness. Using algebraic techniques, we derive an invariant that summarizes the steady-state relationship between the phospho-forms of IDH. We use the invariant in combination with kinetic data on IDHKP to calculate IDH activity at a range of total IDH levels and find that our model predicts robustness. Our work unifies much of the known biochemistry of the IDH regulatory system into a single quantitative framework and highlights the importance of constructing biochemically realistic models in systems biology. PMID:23192354

  12. Preparation and Characterization of Silica-Coated Magnetic–Fluorescent Bifunctional Microspheres

    Directory of Open Access Journals (Sweden)

    Xiao Qi

    2009-01-01

    Full Text Available Abstract Bifunctional magnetic–fluorescent composite nanoparticles (MPQDs with Fe3O4MPs and Mn:ZnS/ZnS core–shell quantum dots (QDs encapsulated in silica spheres were synthesized through reverse microemulsion method and characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, vibration sample magnetometer, and photoluminescence (PL spectra. Our strategy could offer the following features: (1 the formation of Mn:ZnS/ZnS core/shell QDs resulted in enhancement of the PL intensity with respect to that of bare Mn:ZnS nanocrystals due to the effective elimination of the surface defects; (2 the magnetic nanoparticles were coated with silica, in order to reduce any detrimental effects on the QD PL by the magnetic cores; and (3 both Fe3O4MPs and Mn:ZnS/ZnS core–shell QDs were encapsulated in silica spheres, and the obtained MPQDs became water soluble. The experimental conditions for the silica coating on the surface of Fe3O4nanoparticles, such as the ratio of water to surfactant (R, the amount of ammonia, and the amount of tetraethoxysilane, on the photoluminescence properties of MPQDs were studied. It was found that the silica coating on the surface of Fe3O4could effectively suppress the interaction between the Fe3O4and the QDs under the most optimal parameters, and the emission intensity of MPQDs showed a maximum. The bifunctional MPQDs prepared under the most optimal parameters have a typical diameter of 35 nm and a saturation magnetization of 4.35 emu/g at room temperature and exhibit strong photoluminescence intensity.

  13. Arabidopsis RIBA Proteins: Two out of Three Isoforms Have Lost Their Bifunctional Activity in Riboflavin Biosynthesis

    Science.gov (United States)

    Hiltunen, Hanna-Maija; Illarionov, Boris; Hedtke, Boris; Fischer, Markus; Grimm, Bernhard

    2012-01-01

    Riboflavin serves as a precursor for flavocoenzymes (FMN and FAD) and is essential for all living organisms. The two committed enzymatic steps of riboflavin biosynthesis are performed in plants by bifunctional RIBA enzymes comprised of GTP cyclohydrolase II (GCHII) and 3,4-dihydroxy-2-butanone-4-phosphate synthase (DHBPS). Angiosperms share a small RIBA gene family consisting of three members. A reduction of AtRIBA1 expression in the Arabidopsis rfd1mutant and in RIBA1 antisense lines is not complemented by the simultaneously expressed isoforms AtRIBA2 and AtRIBA3. The intensity of the bleaching leaf phenotype of RIBA1 deficient plants correlates with the inactivation of AtRIBA1 expression, while no significant effects on the mRNA abundance of AtRIBA2 and AtRIBA3 were observed. We examined reasons why both isoforms fail to sufficiently compensate for a lack of RIBA1 expression. All three RIBA isoforms are shown to be translocated into chloroplasts as GFP fusion proteins. Interestingly, both AtRIBA2 and AtRIBA3 have amino acid exchanges in conserved peptides domains that have been found to be essential for the two enzymatic functions. In vitro activity assays of GCHII and DHBPS with all of the three purified recombinant AtRIBA proteins and complementation of E. coli ribA and ribB mutants lacking DHBPS and GCHII expression, respectively, confirmed the loss of bifunctionality for AtRIBA2 and AtRIBA3. Phylogenetic analyses imply that the monofunctional, bipartite RIBA3 proteins, which have lost DHBPS activity, evolved early in tracheophyte evolution. PMID:23203051

  14. Gently reduced graphene oxide incorporated into cobalt oxalate rods as bifunctional oxygen electrocatalyst

    International Nuclear Information System (INIS)

    Phihusut, Doungkamon; Ocon, Joey D.; Jeong, Beomgyun; Kim, Jin Won; Lee, Jae Kwang; Lee, Jaeyoung

    2014-01-01

    Graphical abstract: - Abstract: Water-oxygen electrochemistry is at the heart of key renewable energy technologies (fuel cells, electrolyzers, and metal-air batteries) due to the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Although much effort has been devoted to the development of improved bifunctional electrocatalysts, an inexpensive, highly active oxygen electrocatalyst, however, remains to be a challenge. In this paper, we present a facile and robust method to create gently reduced graphene oxide incorporated into cobalt oxalate microstructures (CoC 2 O 4 /gRGO) and demonstrate its excellent and stable electrocatalytic activity in both OER and ORR, arising from the inherent properties of the components and their physicochemical interaction. Our synthesis technique also explores a single pot method to partially reduce graphene oxide and form CoC 2 O 4 structures while maintaining the solution processability of reduced graphene oxide. While the OER activity of CoC 2 O 4 /gRGO is exclusively due to CoC 2 O 4 , which transformed into OER-active Co species, the combination with gRGO significantly improves OER stability. On the other hand, CoC 2 O 4 /gRGO exhibits synergistic effect towards ORR, via a quasi-four-electron pathway, leading to a slightly higher ORR limiting current than Pt/C. Remarkably, gRGO offers dual functionality, contributing to ORR activity via the N-functional groups and also enhancing OER stability through the gRGO coating around CoC 2 O 4 structures. Our results suggest a new class of metal-carbon composite that has the potential to be alternative bifunctional catalysts for regenerative fuel cells and metal-air batteries

  15. 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 ...

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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...

  4. 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...

  5. 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

  6. 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.)

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. A bifunctional endoglucanase/endoxylanase from Cellulomonas flavigena with potential use in industrial processes at different pH.

    Science.gov (United States)

    Pérez-Avalos, Odilia; Sánchez-Herrera, Leticia M; Salgado, Luis M; Ponce-Noyola, Teresa

    2008-07-01

    Cellulomonas flavigena CDBB-531 was found to secrete a bifunctional cellulase/xylanase with a molecular mass of 49 kDa and pI 4.3. This enzyme was active on Remazol brilliant blue-carboxymethylcellulose (RBB-CMC) and Remazol brilliant blue-xylan (RBB-X). Based on thin-layer chromatographic analysis of the degradation products, the cellulase activity produced glucose, cellobiose, cellotriose, and cellotetraose from CMC as the substrate. When xylan from birchwood was used, end products were xylose, arabinose, and xylobiose. The bifunctional enzyme showed a pH optimum of 6 for cellulase activity and 9 for xylanase activity, which pointed out that this enzyme had separate sites for each activity. In both cases, the apparent optimum temperature was 50 degrees C. The predicted amino acid sequence of purified protein showed similarity with the catalytic domain of several glycosyl hydrolases of family 10.

  14. Purification, crystallization and preliminary X-ray crystallographic analysis of rice bifunctional α-amylase/subtilisin inhibitor from Oryza sativa

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yi-Hung [Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076,Taiwan (China); Peng, Wen-Yan [Institute of Bioinformatics and Structural Biology, National Tsing-Hua University, Hsinchu 30013,Taiwan (China); Huang, Yen-Chieh [Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076,Taiwan (China); Guan, Hong-Hsiang; Hsieh, Ying-Cheng [Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076,Taiwan (China); Institute of Bioinformatics and Structural Biology, National Tsing-Hua University, Hsinchu 30013,Taiwan (China); Liu, Ming-Yih [Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076,Taiwan (China); Chang, Tschining [Department of Hospitality Management, Nan Jeon Institute of Technology, Yen-Shui, Tainan 73746,Taiwan (China); Chen, Chun-Jung, E-mail: cjchen@nsrrc.org.tw [Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076,Taiwan (China); Department of Physics, National Tsing-Hua University, Hsinchu 30013,Taiwan (China)

    2006-08-01

    The crystallization of rice α-amylase/subtilisin bifunctional inhibitor is reported. Rice bifunctional α-amylase/subtilisin inhibitor (RASI) can inhibit both α-amylase from larvae of the red flour beetle (Tribolium castaneum) and subtilisin from Bacillus subtilis. The synthesis of RASI is up-regulated during the late milky stage in developing seeds. The 8.9 kDa molecular-weight RASI from rice has been crystallized using the hanging-drop vapour-diffusion method. According to 1.81 Å resolution X-ray diffraction data from rice RASI crystals, the crystal belongs to space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 79.99, b = 62.95, c = 66.70 Å. Preliminary analysis indicates two RASI molecules in an asymmetric unit with a solvent content of 44%.

  15. Crystallization and preliminary X-ray analysis of a bifunctional catalase-phenol oxidase from Scytalidium thermophilum

    International Nuclear Information System (INIS)

    Sutay Kocabas, Didem; Pearson, Arwen R.; Phillips, Simon E. V.; Bakir, Ufuk; Ogel, Zumrut B.; McPherson, Michael J.; Trinh, Chi H.

    2009-01-01

    The bifunctional enzyme catalase-phenol oxidase from S. thermophilum was crystallized by the hanging-drop vapour-diffusion method in space group P2 1 and diffraction data were collected to 2.8 Å resolution. Catalase-phenol oxidase from Scytalidium thermophilum is a bifunctional enzyme: its major activity is the catalase-mediated decomposition of hydrogen peroxide, but it also catalyzes phenol oxidation. To understand the structural basis of this dual functionality, the enzyme, which has been shown to be a tetramer in solution, has been purified by anion-exchange and gel-filtration chromatography and has been crystallized using the hanging-drop vapour-diffusion technique. Streak-seeding was used to obtain larger crystals suitable for X-ray analysis. Diffraction data were collected to 2.8 Å resolution at the Daresbury Synchrotron Radiation Source. The crystals belonged to space group P2 1 and contained one tetramer per asymmetric unit

  16. Nitrogen-Doped Graphene on Transition Metal Substrates as Efficient Bifunctional Catalysts for Oxygen Reduction and Oxygen Evolution Reactions.

    Science.gov (United States)

    Zhou, Si; Liu, Nanshu; Wang, Zhiyu; Zhao, Jijun

    2017-07-12

    Composites of transition metal and carbon-based materials are promising bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), and are widely used in rechargeable metal-air batteries. However, the mechanism of their enhanced bicatalytic activities remains elusive. Herein, we construct N-doped graphene supported by Co(111) and Fe(110) substrates as bifunctional catalysts for ORR and OER in alkaline media. First-principles calculations show that these heterostructures possess a large number of active sites for ORR and OER with overpotentials comparable to those of noble metal benchmark catalysts. The catalytic activity is modulated by the coupling strength between graphene and the metal substrates, as well as the charge distribution in the graphitic sheet, which is delicately mediated by N dopants. These theoretical results uncover the key parameters that govern the bicatalytic properties of hybrid materials and help prescribe the principles for designing multifunctional electrocatalysts of high performance.

  17. Hydrophilic cobalt sulfide nanosheets as a bifunctional catalyst for oxygen and hydrogen evolution in electrolysis of alkaline aqueous solution.

    Science.gov (United States)

    Zhu, Mingchao; Zhang, Zhongyi; Zhang, Hu; Zhang, Hui; Zhang, Xiaodong; Zhang, Lixue; Wang, Shicai

    2018-01-01

    Hydrophilic medium and precursors were used to synthesize a hydrophilic electro-catalyst for overall water splitting. The cobalt sulfide (Co 3 S 4 ) catalyst exhibits a layered nanosheet structure with a hydrophilic surface, which can facilitate the diffusion of aqueous substrates into the electrode pores and towards the active sites. The Co 3 S 4 catalyst shows excellent bifunctional catalytic activity for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline solution. The assembled water electrolyzer based on Co 3 S 4 exhibits better performance and stability than that of Pt/C-RuO 2 catalyst. Thereforce the hydrophilic Co 3 S 4 is a highly promising bifunctional catalyst for the overall water splitting reaction. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Functionalization of nanoparticle titanium dioxide with different bifunctional organic molecules and trimers of transition compounds for obtaining new materials

    International Nuclear Information System (INIS)

    Rivera Martinez, Maria Cinthya

    2012-01-01

    Functionalization of titanium dioxide in nanoporous anatase phase is investigated for obtaining new nanomaterials. Functionalizations were performed using two heating methods: the conventional of refluxing heating method and microwave irradiation with bifunctional organic molecules is used to study how to anchor molecules and the change in the wettability of the material. Besides, reactions with organic molecules were performed as the derived from nanoproxene. The growth layer by layer is performed using the bifunctional molecules previous for the immobilization of cobalt trimers. Functionalized molecules were characterized by infrared spectroscopy, X-ray diffraction, contact angle, scanning electron microscopy, x-ray elemental analysis, plasma atomic emission spectroscopy coupled inductively, x-ray photoelectron spectroscopy and thermogravimetric analysis. This type of functionalizations on nanoporous titanium dioxide could potentially improve optical sensitivity and activity of this nanomaterial in the visible region. (author) [es

  19. Post-modified acid-base bifunctional MIL-101(Cr) for one-pot deacetalization-Knoevenagel reaction

    Energy Technology Data Exchange (ETDEWEB)

    Mu, Manman [Tianjin University, School of Science (China); Yan, Xilong; Li, Yang; Chen, Ligong, E-mail: lgchen@tju.edu.cn [Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) (China)

    2017-04-15

    A novel and convenient approach for the construction of the bifunctional MIL-101 material bearing sulfonic acid and amino groups was established via the post-synthetic modification. This material possesses high BET surface area (1446 m{sup 2}/g) and large pore volume (0.77 cm{sup 3}/g). Significantly, this material could serve as a bifunctional heterogeneous catalyst and was initially employed for one-pot deacetalization-Knoevenagel reaction, exhibiting excellent catalytic performance (yield 99.74%). More importantly, it can be easily recovered and reused at least three times. Finally, our proposed catalytic mechanism indicated that amino and the sulfonic acid groups played a synergistic effect on this one-pot deacetalization-Knoevenagel reaction.

  20. 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)

  1. 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.

  2. Development of a Sono-Assembled, Bifunctional Soy Peptide Nanoparticle for Cellular Delivery of Hydrophobic Active Cargoes

    DEFF Research Database (Denmark)

    Zhang, Yuanhong; Zhao, Mouming; Ning, Zhengxiang

    2018-01-01

    Soy proteins are prone to aggregate upon proteolysis, hindering their sustainable development in food processing. Here, a continuous work on the large insoluble peptide aggregates was carried out, aiming to develop a new type of soy peptide-based nanoparticle (SPN) for active cargo delivery. Sono...... in protecting glutamate-induced toxicity in PC12 cells, where the matrix SPN can simultaneously reduce lipid peroxidation and elevate antioxidant enzymes levels, innovatively demonstrating its bifunctionality during cellular delivery....

  3. L-Threonine-derived novel bifunctional phosphine-sulfonamide catalyst-promoted enantioselective aza-morita-Baylis-Hillman reaction

    KAUST Repository

    Zhong, Fangrui

    2011-03-18

    A series of novel bifunctional phosphine-sulfonamide organic catalysts were designed and readily prepared from natural amino acids, and they were utilized to promote enantioselective aza-Morita-Baylis-Hillman (MBH) reactions. l-Threonine-derived phosphine-sulfonamide 9b was found to be the most efficient catalyst, affording the desired aza-MBH adducts in high yields and with excellent enantioselectivities. © 2011 American Chemical Society.

  4. Catalysis engineering of bifunctional solids for the one-step synthesis of liquid fuels from syngas: A review

    OpenAIRE

    Sartipi, S.; Makkee, M.; Kapteijn, F.; Gascon, J.

    2014-01-01

    The combination of acidic zeolites and Fischer–Tropsch synthesis (FTS) catalysts for one-step production of liquid fuels from syngas is critically reviewed. Bifunctional systems are classified by the proximity between FTS and acid functionalities on three levels: reactor, catalyst particle, and active phase. A thorough analysis of the published literature on this topic reveals that efficiency in the production of liquid fuels correlates well with the proximity of FTS and acid sites. Moreover,...

  5. Adenosine-5?-phosphosulfate ? a multifaceted modulator of bifunctional 3?-phospho-adenosine-5?-phosphosulfate synthases and related enzymes

    OpenAIRE

    Mueller, Jonathan W; Shafqat, Naeem

    2013-01-01

    All sulfation reactions rely on active sulfate in the form of 3?-phospho-adenosine-5?-phosphosulfate (PAPS). In fungi, bacteria, and plants, the enzymes responsible for PAPS synthesis, ATP sulfurylase and adenosine-5?-phosphosulfate (APS) kinase, reside on separate polypeptide chains. In metazoans, however, bifunctional PAPS synthases catalyze the consecutive steps of sulfate activation by converting sulfate to PAPS via the intermediate APS. This intricate molecule and the related nucleotides...

  6. Engineering a trifunctional proline utilization A chimaera by fusing a DNA-binding domain to a bifunctional PutA.

    Science.gov (United States)

    Arentson, Benjamin W; Hayes, Erin L; Zhu, Weidong; Singh, Harkewal; Tanner, John J; Becker, Donald F

    2016-12-01

    Proline utilization A (PutA) is a bifunctional flavoenzyme with proline dehydrogenase (PRODH) and Δ 1 -pyrroline-5-carboxylate (P5C) dehydrogenase (P5CDH) domains that catalyses the two-step oxidation of proline to glutamate. Trifunctional PutAs also have an N-terminal ribbon-helix-helix (RHH) DNA-binding domain and moonlight as autogenous transcriptional repressors of the put regulon. A unique property of trifunctional PutA is the ability to switch functions from DNA-bound repressor to membrane-associated enzyme in response to cellular nutritional needs and proline availability. In the present study, we attempt to construct a trifunctional PutA by fusing the RHH domain of Escherichia coli PutA (EcRHH) to the bifunctional Rhodobacter capsulatus PutA (RcPutA) in order to explore the modular design of functional switching in trifunctional PutAs. The EcRHH-RcPutA chimaera retains the catalytic properties of RcPutA while acquiring the oligomeric state, quaternary structure and DNA-binding properties of EcPutA. Furthermore, the EcRHH-RcPutA chimaera exhibits proline-induced lipid association, which is a fundamental characteristic of functional switching. Unexpectedly, RcPutA lipid binding is also activated by proline, which shows for the first time that bifunctional PutAs exhibit a limited form of functional switching. Altogether, these results suggest that the C-terminal domain (CTD), which is conserved by trifunctional PutAs and certain bifunctional PutAs, is essential for functional switching in trifunctional PutAs. © 2016 The Author(s).

  7. Highly active and durable core-corona structured bifunctional catalyst for rechargeable metal-air battery application.

    Science.gov (United States)

    Chen, Zhu; Yu, Aiping; Higgins, Drew; Li, Hui; Wang, Haijiang; Chen, Zhongwei

    2012-04-11

    A new class of core-corona structured bifunctional catalyst (CCBC) consisting of lanthanum nickelate centers supporting nitrogen-doped carbon nanotubes (NCNT) has been developed for rechargeable metal-air battery application. The nanostructured design of the catalyst allows the core and corona to catalyze the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), respectively. These materials displayed exemplary OER and ORR activity through half-cell testing, comparable to state of the art commercial lanthanum nickelate (LaNiO(3)) and carbon-supported platinum (Pt/C), with added bifunctional capabilities allowing metal-air battery rechargeability. LaNiO(3) and Pt/C are currently the most accepted benchmark electrocatalyst materials for the OER and ORR, respectively; thus with comparable activity toward both of these reactions, CCBC are presented as a novel, inexpensive catalyst component for the cathode of rechargeable metal-air batteries. Moreover, after full-range degradation testing (FDT) CCBC retained excellent activity, retaining 3 and 13 times greater ORR and OER current upon comparison to state of the art Pt/C. Zinc-air battery performances of CCBC is in good agreement with the half-cell experiments with this bifunctional electrocatalyst displaying high activity and stability during battery discharge, charge, and cycling processes. Owing to its outstanding performance toward both the OER and ORR, comparable with the highest performing commercial catalysts to date for each of the respective reaction, coupled with high stability and rechargeability, CCBC is presented as a novel class of bifunctional catalyst material that is very applicable to future generation rechargeable metal-air batteries. © 2012 American Chemical Society

  8. Synergistic bifunctional catalyst design based on perovskite oxide nanoparticles and intertwined carbon nanotubes for rechargeable zinc-air battery applications.

    Science.gov (United States)

    Lee, Dong Un; Park, Hey Woong; Park, Moon Gyu; Ismayilov, Vugar; Chen, Zhongwei

    2015-01-14

    Advanced morphology of intertwined core-corona structured bifunctional catalyst (IT-CCBC) is introduced where perovskite lanthanum nickel oxide nanoparticles (LaNiO3 NP) are encapsulated by high surface area network of nitrogen-doped carbon nanotubes (NCNT) to produce highly active and durable bifunctional catalyst for rechargeable metal-air battery applications. The unique composite morphology of IT-CCBC not only enhances the charge transport property by providing rapid electron-conduction pathway but also facilitates in diffusion of hydroxyl and oxygen reactants through the highly porous framework. Confirmed by electrochemical half-cell testing, IT-CCBC in fact exhibits very strong synergy between LaNiO3 NP and NCNT demonstrating bifunctionality with significantly improved catalytic activities of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Furthermore, when compared to the state-of-art catalysts, IT-CCBC outperforms Pt/C and Ir/C in terms of ORR and OER, respectively, and shows improved electrochemical stability compared to them after cycle degradation testing. The practicality of the catalyst is corroborated by testing in a realistic rechargeable zinc-air battery utilizing atmospheric air in ambient conditions, where IT-CCBC demonstrates superior charge and discharge voltages and long-term cycle stability with virtually no battery voltage fading. These improved electrochemical properties of the catalyst are attributed to the nanosized dimensions of LaNiO3 NP controlled by simple hydrothermal technique, which enables prolific growth of and encapsulation by highly porous NCNT network. The excellent electrochemical results presented in this study highlight IT-CCBC as highly efficient and commercially viable bifunctional catalyst for rechargeable metal-air battery applications.

  9. ZIF-67 incorporated with carbon derived from pomelo peels: A highly efficient bifunctional catalyst for oxygen reduction/evolution reactions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao; Yin, Feng-Xiang; Chen, Biao-Hua; He, Xiao-Bo; Lv, Peng-Liang; Ye, Cai-Yun; Liu, Di-Jia

    2017-05-01

    Developing carbon catalyst materials using natural, abundant and renewable resources as precursors plays an increasingly important role in clean energy generation and environmental protection. In this work, N-doped pomelo-peel-derived carbon (NPC) materials were prepared using a widely available food waste-pomelo peels and melamine. The synthetic NPC exhibits well-defined porosities and a highly doped-N content (e.g. 6.38 at% for NPC-2), therefore affords excellent oxygen reduction reaction (ORR) catalytic activities in alkaline electrolytes. NPC was further integrated with ZIF-67 to form ZIF-67@NPC hybrids through solvothermal reactions. The hybrid catalysts show substantially enhanced ORR catalytic activities comparable to that of commercial 20 wa Pt/C. Furthermore, the catalysts also exhibit excellent oxygen evolution reaction (OER) catalytic activities. Among all prepared ZIF-67@NPC hybrids, the optimal composition with ZIF-67 to NPC ratio of 2:1 exhibits the best ORR and OER bifunctional catalytic performance and the smallest Delta E (E-OER@10 mA cm(-2)-E-ORR@-1 mA cm(-2)) value of 0.79 V. The catalyst also demonstrated desirable 4-electron transfer pathways and superior catalytic stabilities. The Co-N-4 in ZIF-67, electrochemical active surface area, and the strong interactions between ZIF-67 and NPC are attributed as the main contributors to the bifunctional catalytic activities. These factors act synergistically, resulting in substantially enhanced bifunctional catalytic activities and stabilities; consequently, this hybrid catalyst is among the best of the reported bifunctional electrocatalysts and is promising for use in metal-air batteries and fuel cells. (C) 2016 Elsevier B.V. All rights reserved.

  10. 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

  11. A fundamental trade-off in covalent switching and its circumvention by enzyme bifunctionality in glucose homeostasis.

    Science.gov (United States)

    Dasgupta, Tathagata; Croll, David H; Owen, Jeremy A; Vander Heiden, Matthew G; Locasale, Jason W; Alon, Uri; Cantley, Lewis C; Gunawardena, Jeremy

    2014-05-09

    Covalent modification provides a mechanism for modulating molecular state and regulating physiology. A cycle of competing enzymes that add and remove a single modification can act as a molecular switch between "on" and "off" and has been widely studied as a core motif in systems biology. Here, we exploit the recently developed "linear framework" for time scale separation to determine the general principles of such switches. These methods are not limited to Michaelis-Menten assumptions, and our conclusions hold for enzymes whose mechanisms may be arbitrarily complicated. We show that switching efficiency improves with increasing irreversibility of the enzymes and that the on/off transition occurs when the ratio of enzyme levels reaches a value that depends only on the rate constants. Fluctuations in enzyme levels, which habitually occur due to cellular heterogeneity, can cause flipping back and forth between on and off, leading to incoherent mosaic behavior in tissues, that worsens as switching becomes sharper. This trade-off can be circumvented if enzyme levels are correlated. In particular, if the competing catalytic domains are on the same protein but do not influence each other, the resulting bifunctional enzyme can switch sharply while remaining coherent. In the mammalian liver, the switch between glycolysis and gluconeogenesis is regulated by the bifunctional 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2). We suggest that bifunctionality of PFK-2/FBPase-2 complements the metabolic zonation of the liver by ensuring coherent switching in response to insulin and glucagon.

  12. Nanocarbon/oxide composite catalysts for bifunctional oxygen reduction and evolution in reversible alkaline fuel cells: A mini review

    Science.gov (United States)

    Chen, Mengjie; Wang, Lei; Yang, Haipeng; Zhao, Shuai; Xu, Hui; Wu, Gang

    2018-01-01

    A reversible fuel cell (RFC), which integrates a fuel cell with an electrolyzer, is similar to a rechargeable battery. This technology lies on high-performance bifunctional catalysts for the oxygen reduction reaction (ORR) in the fuel cell mode and the oxygen evolution reaction (OER) in the electrolyzer mode. Current catalysts are platinum group metals (PGM) such as Pt and Ir, which are expensive and scarce. Therefore, it is highly desirable to develop PGM-free catalysts for large-scale application of RFCs. In this mini review, we discussed the most promising nanocarbon/oxide composite catalysts for ORR/OER bifunctional catalysis in alkaline media, which is mainly based on our recent progress. Starting with the effectiveness of selected oxides and nanocarbons in terms of their activity and stability, we outlined synthetic methods and the resulting structures and morphologies of catalysts to provide a correlation between synthesis, structure, and property. A special emphasis is put on understanding of the possible synergistic effect between oxide and nanocarbon for enhanced performance. Finally, a few nanocomposite catalysts are discussed as typical examples to elucidate the rules of designing highly active and durable bifunctional catalysts for RFC applications.

  13. Synthesis of deuterium-labeled analogs of the lipid hydroperoxide-derived bifunctional electrophile 4-oxo-2(E)-nonenal.

    Science.gov (United States)

    Arora, Jasbir S; Oe, Tomoyuki; Blair, Ian A

    2011-05-15

    Lipid hydroperoxides undergo homolytic decomposition into the bifunctional 4-hydroxy-2( E )-nonenal and 4-oxo-2( E )-nonenal (ONE). These bifunctional electrophiles are highly reactive and can readily modify intracellular molecules including glutathione (GSH), deoxyribonucleic acid (DNA) and proteins. Lipid hydroperoxide-derived bifunctional electrophiles are thought to contribute to the pathogenesis of a number of diseases. ONE is an α , β -unsaturated aldehyde that can react in multiple ways and with glutathione, proteins and DNA. Heavy isotope-labeled analogs of ONE are not readily available for conducting mechanistic studies or for use as internal standards in mass spectrometry (MS)-based assays. An efficient onestep cost-effective method has been developed for the preparation of C-9 deuterium-labeled ONE. In addition, a method for specific deuterium labeling of ONE at C-2, C-3 or both C-2 and C-3 has been developed. This latter method involved the selective reduction of an intermediate alkyne either by lithium aluminum hydride or lithium aluminum deuteride and quenching with water or deuterium oxide. The availability of these heavy isotope analogs will be useful as internal standards for quantitative studies employing MS and for conducting mechanistic studies of complex interactions between ONE and DNA bases as well as between ONE and proximal amino acid residues in peptides and proteins.

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. The Mycobacterium tuberculosis Rv2540c DNA sequence encodes a bifunctional chorismate synthase

    Directory of Open Access Journals (Sweden)

    Santos Diógenes S

    2008-04-01

    Full Text Available Abstract Background The emergence of multi- and extensively-drug resistant Mycobacterium tuberculosis strains has created an urgent need for new agents to treat tuberculosis (TB. The enzymes of shikimate pathway are attractive targets to the development of antitubercular agents because it is essential for M. tuberculosis and is absent from humans. Chorismate synthase (CS is the seventh enzyme of this route and catalyzes the NADH- and FMN-dependent synthesis of chorismate, a precursor of aromatic amino acids, naphthoquinones, menaquinones, and mycobactins. Although the M. tuberculosis Rv2540c (aroF sequence has been annotated to encode a chorismate synthase, there has been no report on its correct assignment and functional characterization of its protein product. Results In the present work, we describe DNA amplification of aroF-encoded CS from M. tuberculosis (MtCS, molecular cloning, protein expression, and purification to homogeneity. N-terminal amino acid sequencing, mass spectrometry and gel filtration chromatography were employed to determine identity, subunit molecular weight and oligomeric state in solution of homogeneous recombinant MtCS. The bifunctionality of MtCS was determined by measurements of both chorismate synthase and NADH:FMN oxidoreductase activities. The flavin reductase activity was characterized, showing the existence of a complex between FMNox and MtCS. FMNox and NADH equilibrium binding was measured. Primary deuterium, solvent and multiple kinetic isotope effects are described and suggest distinct steps for hydride and proton transfers, with the former being more rate-limiting. Conclusion This is the first report showing that a bacterial CS is bifunctional. Primary deuterium kinetic isotope effects show that C4-proS hydrogen is being transferred during the reduction of FMNox by NADH and that hydride transfer contributes significantly to the rate-limiting step of FMN reduction reaction. Solvent kinetic isotope effects and

  19. 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.

  20. 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...

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Bifunctional recombinant fusion enzyme between maltooligosyltrehalose synthase and maltooligosyltrehalose trehalohydrolase of thermophilic microorganism Metallosphaera hakonensis.

    Science.gov (United States)

    Seo, Ju-Seok; An, Ju Hee; Cheong, Jong-Joo; Choi, Yang Do; Kim, Chung Ho

    2008-09-01

    MhMTS and MhMTH are trehalose (alpha-D-glucopyranosyl- [1,1]-alpha-D-glucopyranose) biosynthesis genes of the thermophilic microorganism Metallosphaera hakonensis, and encode a maltooligosyltrehalose synthase (MhMTS) and a maltooligosyltrehalose trehalohydrolase (MhMTH), respectively. In this study, the two genes were fused inframe in a recombinant DNA, and expressed in Escherichia coli to produce a bifunctional fusion enzyme, MhMTSH. Similar to the two-step reactions with MhMTS and MhMTH, the fusion enzyme catalyzed the sequential reactions on maltopentaose, maltotriosyltrehalose formation, and following hydrolysis, producing trehalose and maltotriose. Optimum conditions for the fusion enzyme-catalyzed trehalose synthesis were around 70 degrees and pH 5.0-6.0. The MhMTSH fusion enzyme exhibited a high degree of thermostability, retaining 80% of the activity when pre-incubated at 70 degrees for 48 h. The stability was gradually abolished by incubating the fusion enzyme at above 80 degrees . The MhMTSH fusion enzyme was active on various sizes of maltooligosaccharides, extending its substrate specificity to soluble starch, the most abundant natural source of trehalose production.

  11. A bifunctional electrolyte additive for separator wetting and dendrite suppression in lithium metal batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Hao; Xie, Yong; Xiang, Hongfa; Shi, Pengcheng; Liang, Xin; Xu, Wu

    2018-04-01

    Reformulation of electrolyte systems and improvement of separator wettability are vital to electrochemical performances of rechargeable lithium (Li) metal batteries, especially for suppressing Li dendrites. In this work we report a bifunctional electrolyte additive that improves separator wettability and suppresses Li dendrite growth in LMBs. A triblock polyether (Pluronic P123) was introduced as an additive into a commonly used carbonate-based electrolyte. It was found that addition of 0.2~1% (by weight) P123 into the electrolyte could effectively enhance the wettability of polyethylene separator. More importantly, the adsorption of P123 on Li metal surface can act as an artificial solid electrolyte interphase layer and contribute to suppress the growth of Li dendrites. A smooth and dendritic-free morphology can be achieved in the electrolyte with 0.2% P123. The Li||Li symmetric cells with the 0.2% P123 containing electrolyte exhibit a relatively stable cycling stability at high current densities of 1.0 and 3.0 mA cm-2.

  12. Bifunctional polyacrylonitrile fiber-mediated conversion of sucrose to 5-hydroxymethylfurfural in mixed-aqueous systems.

    Science.gov (United States)

    Shi, Xian-Lei; Zhang, Min; Lin, Huikun; Tao, Minli; Li, Yongdan; Zhang, Wenqin

    2015-03-01

    A highly efficient catalytic system composed of a bifunctional polyacrylonitrile fiber (PANF-PA[BnBr]) and a metal chloride was employed to produce 5-hydroxymethylfurfural (HMF) from sucrose in mixed-aqueous systems. The promoter of PANF-PA[BnBr] incorporates protonic acid groups that promote the hydrolysis of the glycosidic bond to convert sucrose into glucose and fructose, and then catalyzes fructose dehydration to HMF, while the ammonium moiety may promote synergetically with the metal chloride the isomerization of glucose to fructose and transfer HMF from the aqueous to the organic phase. The detailed characterization by elemental analysis, FTIR spectroscopy, and SEM confirmed the rangeability of the fiber promoter during the modification and utilization processes. Excellent results in terms of high yield (72.8%) of HMF, superior recyclability (6 cycles) of the process, and effective scale-up and simple separation procedures of the catalytic system were obtained. Moreover, the prominent features (high strength, good flexibility, etc.) of the fibers are very attractive for fix-bed reactor. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Bifunctional separator as a polysulfide mediator for highly stable Li-S batteries

    KAUST Repository

    Abbas, Syed Ali

    2016-05-24

    The shuttling process involving lithium polysulfides is one of the major factors responsible for the degradation in capacity of lithium–sulfur batteries (LSBs). Herein, we demonstrate a novel and simple strategy—using a bifunctional separator, prepared by spraying poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on pristine separator—to obtain long-cycle LSBs. The negatively charged SO3– groups present in PSS act as an electrostatic shield for soluble lithium polysulfides through mutual coulombic repulsion, whereas PEDOT provides chemical interactions with insoluble polysulfides (Li2S, Li2S2). The dual shielding effect can provide an efficient protection from the shuttling phenomenon by confining lithium polysulfides to the cathode side of the battery. Moreover, coating with PEDOT:PSS transforms the surface of the separator from hydrophobic to hydrophilic, thereby improving the electrochemical performance. We observed an ultralow decay of 0.0364% per cycle when we ran the battery for 1000 cycles at 0.25 C—far superior to that of the pristine separator and one of the lowest recorded values reported at a low current density. We examined the versatility of our separator by preparing a flexible battery that functioned well under various stress conditions; it displayed flawless performance. Accordingly, this economical and simple strategy appears to be an ideal platform for commercialization of LSBs.

  14. A self-cleaning Li-S battery enabled by a bifunctional redox mediator

    Science.gov (United States)

    Ren, Y. X.; Zhao, T. S.; Liu, M.; Zeng, Y. K.; Jiang, H. R.

    2017-09-01

    The polysulfide shuttle effect and lithium dendrite growth in lithium-sulfur (Li-S) batteries can repeatedly breach the anodic solid electrolyte interphase (SEI) over cycling. As a result, irreversible short-chain sulfide side products (Li2Sx, x = 1, 2) keep depositing on the Li anode, leading to the active material loss, increasing the Li+ transport resistance, and thereby reducing the cycle life. In this work, indium iodide (InI3) is investigated as a bifunctional electrolyte additive for Li-S batteries to protect the Li anode and decompose the side products spontaneously. On the one hand, Indium (In) is electrodeposited onto the Li anode prior to Li plating during the initial charging process, forming a chemically and mechanically stable SEI to prevent the Li anode from reacting with soluble polysulfide species to form Li2Sx (x = 1, 2) side products. On the other hand, by adequately overcharging the battery, the triiodide/iodide redox mediator is capable of chemically transforming side products deposited on the Li anode and separator into soluble polysulfides, which can be recycled by the cathode. It is shown that the battery with the InI3 additive exhibits a prolonged cycle life, and is capable of retrieving its capacity by a facile overcharging process.

  15. Direct conversion of CO2 into liquid fuels with high selectivity over a bifunctional catalyst

    Science.gov (United States)

    Gao, Peng; Li, Shenggang; Bu, Xianni; Dang, Shanshan; Liu, Ziyu; Wang, Hui; Zhong, Liangshu; Qiu, Minghuang; Yang, Chengguang; Cai, Jun; Wei, Wei; Sun, Yuhan

    2017-10-01

    Although considerable progress has been made in carbon dioxide (CO2) hydrogenation to various C1 chemicals, it is still a great challenge to synthesize value-added products with two or more carbons, such as gasoline, directly from CO2 because of the extreme inertness of CO2 and a high C-C coupling barrier. Here we present a bifunctional catalyst composed of reducible indium oxides (In2O3) and zeolites that yields a high selectivity to gasoline-range hydrocarbons (78.6%) with a very low methane selectivity (1%). The oxygen vacancies on the In2O3 surfaces activate CO2 and hydrogen to form methanol, and C-C coupling subsequently occurs inside zeolite pores to produce gasoline-range hydrocarbons with a high octane number. The proximity of these two components plays a crucial role in suppressing the undesired reverse water gas shift reaction and giving a high selectivity for gasoline-range hydrocarbons. Moreover, the pellet catalyst exhibits a much better performance during an industry-relevant test, which suggests promising prospects for industrial applications.

  16. Bifunctional monomer magnetic imprinted nanomaterials for selective separation of tetracyclines directly from milk samples.

    Science.gov (United States)

    Xu, Yuan; Tang, Yuhai; Zhao, Yayun; Gao, Ruixia; Zhang, Junjie; Fu, Delai; Li, Zhaolun; Li, Hecheng; Tang, Xiaoshuang

    2018-04-01

    Novel magnetic molecularly imprinted nanomaterials (DA + BSA-MMIPs) were prepared adopting bovine serum albumin (BSA) and dopamine as bifunctional monomers for the first time. Besides the role of assistant functional monomer, BSA can exclude the proteins with like charges and promote low molecular weight tetracyclines to be adsorbed. Thus, the DA + BSA-MMIPs could fulfil the selective separation of tetracyclines directly from milk samples. The characteristics, polymerization conditions, and adsorption performances of the resultant nanomaterials were investigated in detail. In addition of uniform imprinting layers, stable crystalline phase, and good magnetism of the DA + BSA-MMIPs, they have rapid binding kinetic, high adsorption capacity, and favorable reusability. The imprinted nanomaterials were coupled with HPLC to selectively extract and determine trace tetracyclines from untreated milk samples. The recoveries of tetracyclines are in the range of 84.1-95.8% with relative standard deviations of less than 6.7%. The developed method is especially suitable for the selective enrichment and detection of target compounds directly from a complex sample with proteins. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Designing calcium phosphate-based bifunctional nanocapsules with bone-targeting properties

    Energy Technology Data Exchange (ETDEWEB)

    Khung, Yit-Lung; Bastari, Kelsen; Cho, Xing Ling; Yee, Wu Aik; Loo, Say Chye Joachim, E-mail: joachimloo@ntu.edu.sg [Nanyang Technological University, School of Materials Science and Engineering (Singapore)

    2012-06-15

    Using sodium dodecyl sulphate micelles as template, hollow-cored calcium phosphate nanocapsules were produced. The surfaces of the nanocapsule were subsequently silanised by a polyethylene glycol (PEG)-based silane with an N-hydroxysuccinimide ester end groups which permits for further attachment with bisphosphonates (BP). Characterisations of these nanocapsules were investigated using Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy, Fourier Transform Infra-Red Spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Dynamic Light Scattering. To further validate the bone-targeting potential, dentine discs were incubated with these functionalised nanocapsules. FESEM analysis showed that these surface-modified nanocapsules would bind strongly to dentine surfaces compared to non-functionalised nanocapsules. We envisage that respective components would give this construct a bifunctional attribute, whereby (1) the shell of the calcium phosphate nanocapsule would serve as biocompatible coating aiding in gradual osteoconduction, while (2) surface BP moieties, acting as targeting ligands, would provide the bone-targeting potential of these calcium phosphate nanocapsules.

  18. Crystal structure of the bifunctional proline utilization A flavoenzyme from Bradyrhizobium japonicum

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Dhiraj; Schuermann, Jonathan P.; White, Tommi A.; Krishnan, Navasona; Sanyal, Nikhilesh; Hura, Greg L.; Tan, Anmin; Henzl, Michael T.; Becker, Donald F.; Tanner, John J. (UNL); (LBNL); (UMC)

    2010-04-26

    The bifunctional proline catabolic flavoenzyme, proline utilization A (PutA), catalyzes the oxidation of proline to glutamate via the sequential activities of FAD-dependent proline dehydrogenase (PRODH) and NAD{sup +}-dependent {Delta}{sup 1}-pyrroline-5-carboxylate dehydrogenase (P5CDH) domains. Although structures for some of the domains of PutA are known, a structure for the full-length protein has not previously been solved. Here we report the 2.1 {angstrom} resolution crystal structure of PutA from Bradyrhizobium japonicum, along with data from small-angle x-ray scattering, analytical ultracentrifugation, and steady-state and rapid-reaction kinetics. PutA forms a ring-shaped tetramer in solution having a diameter of 150 {angstrom}. Within each protomer, the PRODH and P5CDH active sites face each other at a distance of 41 {angstrom} and are connected by a large, irregularly shaped cavity. Kinetics measurements show that glutamate production occurs without a lag phase, suggesting that the intermediate, {Delta}{sup 1}-pyrroline-5-carboxylate, is preferably transferred to the P5CDH domain rather than released into the bulk medium. The structural and kinetic data imply that the cavity serves both as a microscopic vessel for the hydrolysis of {Delta}{sup 1}-pyrroline-5-carboxylate to glutamate semialdehyde and a protected conduit for the transport of glutamate semialdehyde to the P5CDH active site.

  19. Cobalt Phosphide Hollow Polyhedron as Efficient Bifunctional Electrocatalysts for the Evolution Reaction of Hydrogen and Oxygen.

    Science.gov (United States)

    Liu, Mengjia; Li, Jinghong

    2016-01-27

    The development of efficient and low-cost hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts for renewable-energy conversion techniques is highly desired. A kind of hollow polyhedral cobalt phosphide (CoP hollow polyhedron) is developed as efficient bifunctional electrocatalysts for HER and OER templated by Co-centered metal-organic frameworks. The as-prepared CoP hollow polyhedron, which have large specific surface area and high porosity providing rich catalytic active sites, show excellent electrocatalytic performances for both HER and OER in acidic and alkaline media, respectively, with onset overpotentials of 35 and 300 mV, Tafel slopes of 59 and 57 mV dec(-1), and a current density of 10 mA cm(-2) at overpotentials of 159 and 400 mV for HER and OER, respectively, which are remarkably superior to those of particulate CoP (CoP particles) and comparable to those of commercial noble-metal catalysts. In addition, the CoP hollow polyhedron also show good durability after long-term operations.

  20. Activating the Bifunctionality of a Perovskite Oxide toward Oxygen Reduction and Oxygen Evolution Reactions.

    Science.gov (United States)

    Lyu, Yu-Qi; Ciucci, Francesco

    2017-10-18

    This article presents a facile and effective approach to activate the bifunctionality of calcium-manganese perovskites toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). We substituted Nb into the Mn site of CaMnO 3 (CMO) and treated the material with H 2 . The as-obtained CaMn 0.75 Nb 0.25 O 3-δ (H 2 -CMNO) displays the same structure as that of CMO, and compared to that of CMO, H 2 -CMNO exhibits significantly improved OER performance, including a lower overpotential, a reduced Tafel slope, a higher mass activity, and enhanced stability. In addition, the ORR performance of H 2 -CMNO is also greatly enhanced, relative to CMO, with a higher ORR activity and a more efficient electron-transfer pathway. H 2 -CMNO shows an even higher activity-per-catalyst cost and superior stability than that of state-of-the-art materials, such as IrO 2 and Pt/C. This great enhancement in ORR and OER activity of H 2 -CMNO is attributed to several factors, including phase stabilization, optimized e g filling, better OH - adsorption, and improved electrical conductivity.

  1. Three crystal forms of the bifunctional enzyme proline utilization A (PutA) from Bradyrhizobium japonicum

    International Nuclear Information System (INIS)

    Schuermann, Jonathan P.; White, Tommi A.; Srivastava, Dhiraj; Karr, Dale B.; Tanner, John J.

    2008-01-01

    The first diffraction-quality crystals of a PutA protein are reported. One of the three crystal forms described here exhibits pseudo-merohedral twinning. Removal of the N-terminal histidine tag aided the crystallization of another form. Proline utilization A proteins (PutAs) are large (1000–1300 residues) membrane-associated bifunctional flavoenzymes that catalyze the two-step oxidation of proline to glutamate by the sequential action of proline dehydrogenase and Δ 1 -pyrroline-5-carboxylate dehydrogenase domains. Here, the first successful crystallization efforts for a PutA protein are described. Three crystal forms of PutA from Bradyrhizobium japonicum are reported: apparent tetragonal, hexagonal and centered monoclinic. The apparent tetragonal and hexagonal crystals were grown in the presence of PEG 3350 and sodium formate near pH 7. The apparent tetragonal form diffracted to 2.7 Å resolution and exhibited pseudo-merohedral twinning such that the true space group is P2 1 2 1 2 1 with four molecules in the asymmetric unit. The hexagonal form diffracted to 2.3 Å resolution and belonged to space group P6 2 22 with one molecule in the asymmetric unit. Centered monoclinic crystals were grown in ammonium sulfate, diffracted to 2.3 Å resolution and had two molecules in the asymmetric unit. Removing the histidine tag was important in order to obtain the C2 crystal form

  2. Three crystal forms of the bifunctional enzyme proline utilization A (PutA) from Bradyrhizobium japonicum.

    Science.gov (United States)

    Schuermann, Jonathan P; White, Tommi A; Srivastava, Dhiraj; Karr, Dale B; Tanner, John J

    2008-10-01

    Proline utilization A proteins (PutAs) are large (1000-1300 residues) membrane-associated bifunctional flavoenzymes that catalyze the two-step oxidation of proline to glutamate by the sequential action of proline dehydrogenase and Delta(1)-pyrroline-5-carboxylate dehydrogenase domains. Here, the first successful crystallization efforts for a PutA protein are described. Three crystal forms of PutA from Bradyrhizobium japonicum are reported: apparent tetragonal, hexagonal and centered monoclinic. The apparent tetragonal and hexagonal crystals were grown in the presence of PEG 3350 and sodium formate near pH 7. The apparent tetragonal form diffracted to 2.7 A resolution and exhibited pseudo-merohedral twinning such that the true space group is P2(1)2(1)2(1) with four molecules in the asymmetric unit. The hexagonal form diffracted to 2.3 A resolution and belonged to space group P6(2)22 with one molecule in the asymmetric unit. Centered monoclinic crystals were grown in ammonium sulfate, diffracted to 2.3 A resolution and had two molecules in the asymmetric unit. Removing the histidine tag was important in order to obtain the C2 crystal form.

  3. Highly Active and Durable Nanocrystal-Decorated Bifunctional Electrocatalyst for Rechargeable Zinc-Air Batteries.

    Science.gov (United States)

    Lee, Dong Un; Park, Moon Gyu; Park, Hey Woong; Seo, Min Ho; Wang, Xiaolei; Chen, Zhongwei

    2015-09-21

    A highly active and durable bifunctional electrocatalyst that consists of cobalt oxide nanocrystals (Co3 O4 NC) decorated on the surface of N-doped carbon nanotubes (N-CNT) is introduced as effective electrode material for electrically rechargeable zinc-air batteries. This active hybrid catalyst is synthesized by a facile surfactant-assisted method to produce Co3 O4 NC that are then decorated on the surface of N-CNT through hydrophobic attraction. Confirmed by half-cell testing, Co3 O4 NC/N-CNT demonstrates superior oxygen reduction and oxygen evolution catalytic activities and has a superior electrochemical stability compared to Pt/C and Ir/C. Furthermore, rechargeable zinc-air battery testing of Co3 O4 NC/N-CNT reveals superior galvanodynamic charge and discharge voltages with a significantly extended cycle life of over 100 h, which suggests its potential as a replacement for precious-metal-based catalysts for electric vehicles and grid energy storage applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Subunit topography of RNA polymerase from Escherichia coli. A cross-linking study with bifunctional reagents.

    Science.gov (United States)

    Hillel, Z; Wu, C W

    1977-07-26

    The quaternary structures of Escherichia coli DNA-dependent RNA polymerase holenzyme (alpha 2 beta beta' sigma) and core enzyme (alpha 2 beta beta') have been investigated by chemical cross-linking with a cleavable bifunctional reagent, methyl 4-mercaptobutyrimidate, and noncleavable reagents, dimethyl suberimidate and N,N'-(1,4-phenylene)bismaleimide. A model of the subunit organization deduced from cross-linked subunit neighbors identified by dodecyl sulfate-polyacrylamide gel electrophoresis indicates that the large beta and beta' subunits constitute the backbone of both core and holoenzyme, while sigma and two alpha subunits interact with this structure along the contact domain of beta and beta' subunits. In holoenzyme, sigma subunit is in the vicinity of at least one alpha subunit. The two alpha subunits are close to each other in holoenzyme, core enzyme, and the isolated alpha 2 beta complex. Cross-linking of the "premature" core and holoenzyme intermediates in the in vitro reconstitution of active enzyme from isolated subunits suggests that these species are composed of subunit complexes of molecular weight lower than that of native core and holoenzyme, respectively. The structural information obtained for RNA polymerase and its subcomplexes has important implications for the enzyme-promoter recognition as well as the mechanism of subunit assembly of the enzyme.

  5. A new bifunctional hybrid nanostructure as an active platform for photothermal therapy and MR imaging.

    Science.gov (United States)

    Khafaji, Mona; Vossoughi, Manouchehr; Hormozi-Nezhad, M Reza; Dinarvand, Rassoul; Börrnert, Felix; Irajizad, Azam

    2016-06-14

    As a bi-functional cancer treatment agent, a new hybrid nanostructure is presented which can be used for photothermal therapy by exposure to one order of magnitude lower laser powers compared to similar nanostructures in addition to substantial enhancment in magnetic resonance imaging (MRI) contrast. This gold-iron oxide hybrid nanostructure (GIHN) is synthesized by a cost-effective and high yield water-based approach. The GIHN is sheilded by PEG. Therefore, it shows high hemo and biocompatibility and more than six month stability. Alongside earlier nanostructures, the heat generation rate of GIHN is compareable with surfactnat-capped gold nanorods (GNRs). Two reasons are behind this enhancement: Firstly the distance between GNRs and SPIONs is adjusted in a way that the surface plasmon resonance of the new nanostructure is similar to bare GNRs and secondly the fraction of GNRs is raised in the hybrid nanostructure. GIHN is then applied as a photothermal agent using laser irradiation with power as low as 0.5 W.cm(-2) and only 32% of human breast adenocarcinoma cells could survive. The GIHN also acts as a dose-dependent transvers relaxation time (T2) MRI contrast agent. The results show that the GINH can be considered as a good candidate for multimodal photothermal therapy and MRI.

  6. Hypoxia targeted bifunctional suicide gene expression enhances radiotherapy in vitro and in vivo

    International Nuclear Information System (INIS)

    Sun, Xiaorong; Xing, Ligang; Deng, Xuelong; Hsiao, Hung Tsung; Manami, Akiko; Koutcher, Jason A.; Clifton Ling, C.; Li, Gloria C.

    2012-01-01

    Purpose: To investigate whether hypoxia targeted bifunctional suicide gene expression-cytosine deaminase (CD) and uracil phosphoribosyltransferase (UPRT) with 5-FC treatments can enhance radiotherapy. Materials and methods: Stable transfectants of R3327-AT cells were established which express a triple-fusion-gene: CD, UPRT and monomoric DsRed (mDsRed) controlled by a hypoxia inducible promoter. Hypoxia-induced expression/function of CDUPRTmDsRed was verified by western blot, flow cytometry, fluorescent microscopy, and cytotoxicity assay of 5-FU and 5-FC. Tumor-bearing mice were treated with 5-FC and local radiation. Tumor volume was monitored and compared with those treated with 5-FC or radiation alone. In addition, the CDUPRTmDsRed distribution in hypoxic regions of tumor sections was visualized with fluorescent microscopy. Results: Hypoxic induction of CDUPRTmDsRed protein correlated with increased sensitivity to 5-FC and 5-FU. Significant radiosensitization effects were detected after 5-FC treatments under hypoxic conditions. In the tumor xenografts, the distribution of CDUPRTmDsRed expression visualized with fluorescence microscopy was co-localized with the hypoxia marker pimonidazole positive staining cells. Furthermore, administration of 5-FC to mice in combination with local irradiation resulted in significant tumor regression, as in comparison with 5-FC or radiation treatments alone. Conclusions: Our data suggest that the hypoxia-inducible CDUPRT/5-FC gene therapy strategy has the ability to specifically target hypoxic cancer cells and significantly improve the tumor control in combination with radiotherapy.

  7. Bifunctional Anti-Non-Amyloid Component α-Synuclein Nanobodies Are Protective In Situ.

    Directory of Open Access Journals (Sweden)

    David C Butler

    Full Text Available Misfolding, abnormal accumulation, and secretion of α-Synuclein (α-Syn are closely associated with synucleinopathies, including Parkinson's disease (PD. VH14 is a human single domain intrabody selected against the non-amyloid component (NAC hydrophobic interaction region of α-Syn, which is critical for initial aggregation. Using neuronal cell lines, we show that as a bifunctional nanobody fused to a proteasome targeting signal, VH14PEST can counteract heterologous proteostatic effects of mutant α-Syn on mutant huntingtin Exon1 and protect against α-Syn toxicity using propidium iodide or Annexin V readouts. We compared this anti-NAC candidate to NbSyn87, which binds to the C-terminus of α-Syn. NbSyn87PEST degrades α-Syn as well or better than VH14PEST. However, while both candidates reduced toxicity, VH14PEST appears more effective in both proteostatic stress and toxicity assays. These results show that the approach of reducing intracellular monomeric targets with novel antibody engineering technology should allow in vivo modulation of proteostatic pathologies.

  8. "Click" chemistry mildly stabilizes bifunctional gold nanoparticles for sensing and catalysis.

    Science.gov (United States)

    Li, Na; Zhao, Pengxiang; Liu, Na; Echeverria, María; Moya, Sergio; Salmon, Lionel; Ruiz, Jaime; Astruc, Didier

    2014-07-01

    A large family of bifunctional 1,2,3-triazole derivatives that contain both a polyethylene glycol (PEG) chain and another functional fragment (e.g., a polymer, dendron, alcohol, carboxylic acid, allyl, fluorescence dye, redox-robust metal complex, or a β-cyclodextrin unit) has been synthesized by facile "click" chemistry and mildly coordinated to nanogold particles, thus providing stable water-soluble gold nanoparticles (AuNPs) in the size range 3.0-11.2 nm with various properties and applications. In particular, the sensing properties of these AuNPs are illustrated through the detection of an analogue of a warfare agent (i.e., sulfur mustard) by means of a fluorescence "turn-on" assay, and the catalytic activity of the smallest triazole-AuNPs (core of 3.0 nm) is excellent for the reduction of 4-nitrophenol in water. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Flexible control of cellular encapsulation, permeability, and release in a droplet-templated bifunctional copolymer scaffold.

    Science.gov (United States)

    Chen, Qiushui; Chen, Dong; Wu, Jing; Lin, Jin-Ming

    2016-11-01

    Designing cell-compatible, bio-degradable, and stimuli-responsive hydrogels is very important for biomedical applications in cellular delivery and micro-scale tissue engineering. Here, we report achieving flexible control of cellular microencapsulation, permeability, and release by rationally designing a diblock copolymer, alginate-conjugated poly(N-isopropylacrylamide) (Alg-co-PNiPAM). We use the microfluidic technique to fabricate the bifunctional copolymers into thousands of mono-disperse droplet-templated hydrogel microparticles for controlled encapsulation and triggered release of mammalian cells. In particular, the grafting PNiPAM groups in the synthetic cell-laden microgels produce lots of nano-aggregates into hydrogel networks at elevated temperature, thereafter enhancing the permeability of microparticle scaffolds. Importantly, the hydrogel scaffolds are readily fabricated via on-chip quick gelation by triggered release of Ca 2+ from the Ca-EDTA complex; it is also quite exciting that very mild release of microencapsulated cells is achieved via controlled degradation of hydrogel scaffolds through a simple strategy of competitive affinity of Ca 2+ from the Ca-Alginate complex. This finding suggests that we are able to control cellular encapsulation and release through ion-induced gelation and degradation of the hydrogel scaffolds. Subsequently, we demonstrate a high viability of microencapsulated cells in the microgel scaffolds.

  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. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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.

  1. REVIEW ARTICLE:Future of Lead Chelation – Distribution and Treatment

    Directory of Open Access Journals (Sweden)

    Venkatesh Thuppil

    2012-01-01

    Full Text Available Lead is the major environmental toxin resulting in the ill health and deleterious effect on almost all organs in the human body in a slow and effective manner. The best treatment for lead poisoning is chelation therapy which is next only to prevention. The authors describe the disruption of homeostasis of the human body by lead in various tissues like blood, bones, liver, kidneys and brain; and the ability of lead to enter the cell using calcium channels and calcium receptors like Ca++ dependant K+ ion channels, transient receptor potential channels, T-tubules, calmodulin receptors, inositol trisphosphate receptors and ryanodine receptors. We report a few novel chelating agents like ionophores, decadentate ligands, picolinate ligands, octadentate ligand, allicin, thiamine, that show good potential for being used in chelation therapy. Future of leadpoisoning is a challenge to all and it needs to be meticulously studies to have an economic and health approach.

  2. 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.

  3. Molecular and biochemical characterization of the Fe(III) chelate reductase gene family in Arabidopsis thaliana.

    Science.gov (United States)

    Wu, Huilan; Li, Lihua; Du, Juan; Yuan, Youxi; Cheng, Xudong; Ling, Hong-Qing

    2005-09-01

    Iron chelate reductase is required for iron acquisition from soil and for metabolism in plants. In the genome of Arabidopsis thaliana there are eight genes classified into the iron chelate reductase gene family (AtFROs) based on sequence homology with AtFRO2 (a ferric chelate reductase in Arabidopsis). They are localized on chromosome 1 (three AtFROs) and chromosome 5 (five AtFROs) of Arabidopsis and show a high level of amino acid sequence similarity to each other. An assay for ferric chelate reductase activity revealed that AtFRO2, AtFRO3, AtFRO4, AtFRO5, AtFRO7 and AtFRO8 conferred significantly increased iron reduction activity compared with the control when expressed in yeast cells, indicating that the six AtFROs encode iron chelate reductases functioning in iron homeostasis in Arabidopsis. AtFRO2 displayed the highest iron reduction activity among the AtFROs investigated, further demonstrating that AtFRO2 is a major iron reductase gene in Arabidopsis. AtFRO2 and AtFRO3 were mainly expressed in roots of Arabidopsis, AtFRO5 and AtFRO6 in shoots and flowers, and AtFRO7 in cotyledons and trichomes, whereas the transcription of AtFRO8 was specific for leaf veins. Considering the tissue-specific expression profiles of AtFRO genes, we suggest that AtFRO2 and AtFRO3 are two Fe(III) chelate reductases mainly functioning in iron acquisition and metabolism in Arabidopsis roots, while AtFRO5, AtFRO6, AtFRO7 and AtFRO8 are required for iron homeostasis in different tissues of shoots.

  4. 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

  5. Adsorption of hazardous ions from radioactive waste on chelating cloth filter

    International Nuclear Information System (INIS)

    Sohsah, M.A.; Othman, S.H.; Elanadouli, B.E.

    2005-01-01

    A cloth filter was synthesized by grafting of acrylonitrile/methacrylic acid (80/20) onto cotton cloth using radiation-induced technique followed by amidoximation reaction. The fate of the adsorbed uranium ions from radioactive waste on chelating cloth filter was investigated. The adsorption ability of chelating cloth filter was increased with increasing the ph value from ph 6 to ph 10. The predominant composition of the resulted complex was determined. The chemical adsorption mechanism was confirmed by examining the relationships between the adsorbed amount of the radionuclide and the contact time

  6. IRON CHELATING AND ANTIRADICAL ACTIVITY OF KAYU MANIK LEAVES (Trema orientalis

    Directory of Open Access Journals (Sweden)

    Salprima Yudha S.

    2011-11-01

    Full Text Available A methanol soluble fraction extracted from Kayu Manik leaves (Trema orientalis from Seluma, Bengkulu, exhibited an antiradical activity 69.73% (scavenging activity of the stable 1,1-diphenyl-2-picryl hydrazyl (DPPH free radical that was almost similar to that of 1 mM ascorbic acid. On the other hand, the iron chelating activity was 40.74%. We believe that it would be useful to take the results as an alternative for processing industries and can be observed as a good source of new agent for iron chelator.

  7. Hepatobiliary delivery of polyaminopolycarboxylate chelates: Synthesis and characterization of a cholic acid conjugate of EDTA and biodistribution and imaging studies with its indium-111 chelate

    Energy Technology Data Exchange (ETDEWEB)

    Betebenner, D.A.; Carney, P.L.; Zimmer, A.M.; Kazikiewicz, J.M.; Bruecher, E.S.; Sherry, A.D.; Johnson, D.K. (Abbott Laboratories, Abbott Park, Illinois (USA))

    1991-03-01

    A conjugate in which the steroid nucleus of cholic acid was linked to EDTA via an 11-atom spacer was obtained by reacting the succinimidyl ester of cholic acid with the amine formed by reaction of a benzyl isothiocyanate derivative of EDTA with N-(tert-butoxycarbonyl)ethylenediamine and subsequent deprotection. Potentiometric titration studies with model complexes showed that the EDTA moiety retained the ability to form 1:1 chelates of high thermodynamic stability, although formation constants were some 3-4 log K units lower for complexes of the conjugate than for the analogous chelates with underivatized EDTA. A complex formed between the cholic acid-EDTA conjugate and 111InIII was clearly rapidly into the liver when injected iv into mice, with subsequent excretion from the liver into the gastrointestinal tract being complete within 1 h of injection. Radioscintigraphic imaging studies conducted in a rabbit given the 111In-labeled conjugate also showed early liver uptake followed by rapid clearance from the liver into the intestine, with good visualization of the gallbladder in images obtained at 20-25 min postinjection. It is concluded that conjugation to cholic acid provides a useful means for the hepatobiliary delivery of EDTA chelates that otherwise exhibit predominantly extracellular distribution and renal clearance.

  8. Characterization of radionuclide-chelating agent complexes found in low-level radioactive decontamination waste. Literature review

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R.J.; Felmy, A.R.; Cantrell, K.J.; Krupka, K.M.; Campbell, J.A.; Bolton, H. Jr.; Fredrickson, J.K. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-03-01

    The US Nuclear Regulatory Commission is responsible for regulating the safe land disposal of low-level radioactive wastes that may contain organic chelating agents. Such agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), picolinic acid, oxalic acid, and citric acid, and can form radionuclide-chelate complexes that may enhance the migration of radionuclides from disposal sites. Data from the available literature indicate that chelates can leach from solidified decontamination wastes in moderate concentration (1--100 ppm) and can potentially complex certain radionuclides in the leachates. In general it appears that both EDTA and DTPA have the potential to mobilize radionuclides from waste disposal sites because such chelates can leach in moderate concentration, form strong radionuclide-chelate complexes, and can be recalcitrant to biodegradation. It also appears that oxalic acid and citric acid will not greatly enhance the mobility of radionuclides from waste disposal sites because these chelates do not appear to leach in high concentration, tend to form relatively weak radionuclide-chelate complexes, and can be readily biodegraded. In the case of picolinic acid, insufficient data are available on adsorption, complexation of key radionuclides (such as the actinides), and biodegradation to make definitive predictions, although the available data indicate that picolinic acid can chelate certain radionuclides in the leachates.

  9. Characterization of radionuclide-chelating agent complexes found in low-level radioactive decontamination waste. Literature review

    International Nuclear Information System (INIS)

    Serne, R.J.; Felmy, A.R.; Cantrell, K.J.; Krupka, K.M.; Campbell, J.A.; Bolton, H. Jr.; Fredrickson, J.K.

    1996-03-01

    The US Nuclear Regulatory Commission is responsible for regulating the safe land disposal of low-level radioactive wastes that may contain organic chelating agents. Such agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), picolinic acid, oxalic acid, and citric acid, and can form radionuclide-chelate complexes that may enhance the migration of radionuclides from disposal sites. Data from the available literature indicate that chelates can leach from solidified decontamination wastes in moderate concentration (1--100 ppm) and can potentially complex certain radionuclides in the leachates. In general it appears that both EDTA and DTPA have the potential to mobilize radionuclides from waste disposal sites because such chelates can leach in moderate concentration, form strong radionuclide-chelate complexes, and can be recalcitrant to biodegradation. It also appears that oxalic acid and citric acid will not greatly enhance the mobility of radionuclides from waste disposal sites because these chelates do not appear to leach in high concentration, tend to form relatively weak radionuclide-chelate complexes, and can be readily biodegraded. In the case of picolinic acid, insufficient data are available on adsorption, complexation of key radionuclides (such as the actinides), and biodegradation to make definitive predictions, although the available data indicate that picolinic acid can chelate certain radionuclides in the leachates

  10. Synergistic Activities of an Efflux Pump Inhibitor and Iron Chelators against Pseudomonas aeruginosa Growth and Biofilm Formation

    DEFF Research Database (Denmark)

    Liu, Yang; Yang, Liang; Molin, Søren

    2010-01-01

    The efflux pump inhibitor phenyl-arginine-beta-naphthylamide (PA beta N) was paired with iron chelators 2,2'-dipyridyl, acetohydroxamic acid, and EDTA to assess synergistic activities against Pseudomonas aeruginosa growth and biofilm formation. All of the tested iron chelators synergistically...

  11. 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.

  12. Ascorbic acid as a bifunctional hydrogen bond donor for the synthesis of cyclic carbonates from CO2 under ambient conditions

    KAUST Repository

    Arayachukiat, Sunatda

    2017-07-14

    Readily available ascorbic acid was discovered as an environmentally benign hydrogen bond donor (HBD) for the synthe-sis of cyclic organic carbonates from CO2 and epoxides in the presence of nucleophilic co-catalysts. The ascorbic acid/TBAI (TBAI: tetrabutylammonium iodide) binary system could be applied for the cycloaddition of CO2 to various epoxides under ambient or mild conditions. DFT calculations and catalysis experiments revealed an intriguing bifunctional mechanism in the step of CO2 insertion involving different hydroxyl moieties (enediol, ethyldiol) of the ascorbic acid scaffold.

  13. Enantioselective Alkylation of 2-Oxindoles Catalyzed by a Bifunctional Phase-Transfer Catalyst: Synthesis of (-)-Debromoflustramine B.

    Science.gov (United States)

    Craig, Ryan; Sorrentino, Emiliano; Connon, Stephen J

    2018-03-26

    A new bifunctional phase-transfer catalyst that employs hydrogen bonding as a control element was developed to promote efficient enantioselective S N 2 reactions for the construction all-carbon quaternary stereocenters in high yield and excellent enantioselectivity (up to 97 % ee) utilizing the alkylation of a malleable oxindole substrate. The utility of the methodology was demonstrated through a concise and highly enantioselective synthesis of (-)-debromoflustramine B. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Phenyl-N,N-dibutylcarbamoylmethyl sulfoxide as a new bifunctional extractant for extraction of uranium(VI) in toluene

    International Nuclear Information System (INIS)

    Han Jing-Tian; Sun Guo-Xin; Shao Hua; Bao Bo-Rong; Chen Shu-Feng

    1999-01-01

    A new bifunctional extractant named phenyl-N,N-dibutylcarbamoylmethyl sulfoxide (PCMSO) is synthesized and characterized in order to investigate its selectivity and capability in the extraction from acidic nitrate media in nuclear reprocessing. The extraction of uranium(VI) with PCMSO in toluene has been studied at various concentrations of nitric acid, extractant and salting-out agent (LiNO 3 ). The mechanism of extraction is discussed in the light of the results obtained. The extracted species has also been investigated using FT-IR spectrometry. The related thermodynamic functions were calculated. The IR spectral study was also made of the extracted species. (author)

  15. Stable expression of a bifunctional diterpene synthase in the chloroplast of Chlamydomonas reinhardtii

    DEFF Research Database (Denmark)

    Zedler, Julie Annemarie Zita; Gangl, Doris; Hamberger, Björn Robert

    2015-01-01

    the generation of transgenic lines without the use of antibiotic-resistance genes. Here, we have expressed a bifunctional diterpene synthase in C. reinhardtii chloroplasts. Homoplasmic transformants were obtained with the expressed enzyme accounting for 3.7 % of total soluble protein. The enzyme was purified...... to homogeneity and expression was shown to have a small but reproducible effect on growth rate at the end of log phase growth. These results demonstrate that large recombinant enzymes can be synthesised in the algal chloroplast, and serve to underline its potential as a platform for the biosynthesis of novel...

  16. Engineering a trifunctional proline utilization A chimaera by fusing a DNA-binding domain to a bifunctional PutA

    OpenAIRE

    Arentson, Benjamin?W.; Hayes, Erin?L.; Zhu, Weidong; Singh, Harkewal; Tanner, John?J.; Becker, Donald?F.

    2016-01-01

    Proline utilization A (PutA) is a bifunctional flavoenzyme with proline dehydrogenase (PRODH) and ?1-pyrroline-5-carboxylate (P5C) dehydrogenase (P5CDH) domains that catalyses the two-step oxidation of proline to glutamate. Trifunctional PutAs also have an N-terminal ribbon?helix?helix (RHH) DNA-binding domain and moonlight as autogenous transcriptional repressors of the put regulon. A unique property of trifunctional PutA is the ability to switch functions from DNA-bound repressor to membran...

  17. Recyclable Bifunctional Polystyrene and Silica Gel-Supported Organocatalyst for the Coupling of CO2 with Epoxides.

    Science.gov (United States)

    Kohrt, Christina; Werner, Thomas

    2015-06-22

    A bifunctional ammonium salt covalently bound to a polystyrene or silica support proved to be an efficient and recyclable catalyst for the solvent-free synthesis of cyclic carbonates from epoxides and CO2 . The catalyst can be easily recovered by simple filtration after the reaction and reused in up to 13 consecutive runs with retention of high activity and selectivity even at 90 °C. The scope and limitations of the reaction has been evaluated in terms of reaction conditions and substrate scope. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Modification of bifunctional epoxy resin using CO{sub 2} fixation process and nanoclay

    Energy Technology Data Exchange (ETDEWEB)

    Khoshkish, Morteza; Bouhendi, Hosein, E-mail: H.boohendi@ippi.ac.ir; Vafayan, Mehdi

    2014-10-15

    A bifunctional epoxy resin was modified by using a CO{sub 2} fixation solution process in the presence of tetra n-butyl ammonium bromide (TBAB) as catalyst and the modified treated resin was treated by cloisite 30B as nano additive. The Unmodified epoxy resin (UME), CO{sub 2} fixated modified epoxy resin (CFME), and CFME/clay nano composite (CFMEN), were cured by diethylenetriamine (DETA). A cycloaliphatic compound as a reactive diluent was used to control the viscosity of high viscose CFME. The exfoliation of organoclay in UME and CFME was investigated by X-ray diffraction and activation energy was computed using the advanced integral isoconversional method. The activation energy dependency demonstrated that the mechanism of UME curing did not change in the presence of nanoclay. In contrast, the CO{sub 2} fixation results showed a significant change in the activation energy dependency. The Thermal stability parameters include the initial degradation temperature (IDT), the temperature at the maximum rate of weight loss (T{sub max}), and the decomposition activation energy (E{sub d}) were determined by thermal gravimetry analysis. Dynamic mechanical thermal analysis measurements showed that the presence of organoclay in CFME increases the T{sub g} of nano composite in contrast to UME. The fracture roughness of UME, CFME and CFNE were determined by scanning electron microscope. The exfoliated UME/1%clay nanocomposite was confirmed by TEM image. - Highlights: • A new epoxy resin was synthesized using CO{sub 2} fixation reaction. • The synthesized epoxy resin was modified by an organo nano-clay. • CO{sub 2} fixation noticeably changed the curing mechanism. • CO{sub 2} fixation reaction consumes CO{sub 2} which is a harmful greenhouse gas.

  19. Photocatalytic isotopic exchange between cyclopentane and deuterium over a bifunctional Pt/TiO2 catalyst

    International Nuclear Information System (INIS)

    Courbon, H.; Herrmann, J.M.; Pichat, P.

    1981-01-01

    Cyclopentane-deuterium isotopic exchange (CDIE) was performed at -10 0 C with a C 5 H 10 /D 2 ratio of approx. =6.4% over an illuminated (300 to 410 nm) 0.5 wt% Pt/anatase catalyst. A selectivity in C 5 H 9 D of approx. =90% was found with a total quantum yield of approx. =1.8%. The photocatalytic nature of CDIE under these conditions was established from these results: (i) no CDIE in the absence of photons of wavelengths shorter than the absorption edge of anatase or when TiO 2 was replaced by SiO 2 , whereas the CDIE observed at higher temperatures (from 0 0 C) without uv light mainly produced multiply exchanged cyclopentane, (ii) a linear CDIE rate-illumination time relationship was found, and (iii) an experiment carried out with the same catalyst sample showed that it was capable of exchanging, in successive runs, without decrease in activity, an amount of C 5 H 10 78 times greater than that corresponding to a photoinduced stoichiometric surface reaction. By contrast, CDIE over pure TiO 2 was limited and was only observed for hydroxylated specimens pretreated in D 2 at 300 0 C. It is concluded that (i) CDIE occurred on anatase between weakly adsorbed C 5 H 10 and OD - ions activated by the trapping of photoproduced positive holes, and (ii) Pt, besides attracting the support-free electrons which decreased the recombination of electron-hole pairs, regenerated the titania OD - ions after their isotopic exchange, which involved D 2 dissociative adsorption on the metal and subsequent migration of D atoms to the oxide. This constitutes an example of bifunctional heterogeneous photocatalysis

  20. Enhancing Cooperativity in Bifunctional Acid–Pd Catalysts with Carboxylic Acid-Functionalized Organic Monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Coan, Patrick D. [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States; Ellis, Lucas D. [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States; Griffin, Michael B. [National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States; Schwartz, Daniel K. [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States; Medlin, J. Will [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States

    2018-03-01

    Cooperative catalysts containing a combination of noble metal hydrogenation sites and Bronsted acid sites are critical for many reactions, including the deoxygenation (DO) of biomass-derived oxygenates in the upgrading of pyrolysis oil. One route toward the design of cooperative catalysts is to tether two different catalytically active functions so that they are in close proximity while avoiding undesirable interactions that can block active sites. Here, we deposited carboxylic acid (CA)-functionalized organophosphonate monolayers onto Al2O3-supported Pd nanoparticle catalysts to prepare bifunctional catalysts containing both Bronsted acid and metal sites. Modification with phosphonic acids (PAs) improved activity and selectivity for gas-phase DO reactions, but the degree of improvement was highly sensitive to both the presence and positioning of the CA group, suggesting a significant contribution from both the PA and CA sites. Short spacer lengths of 1-2 methylene groups between the phosphonate head and CA tail were found to yield the best DO rates and selectivities, whereas longer chains performed similarly to self-assembled monolayers having alkyl tails. Results from a combination of density functional theory and Fourier transform infrared spectroscopy suggested that the enhanced catalyst performance on the optimally positioned CAs was due to the generation of strong acid sites on the Al2O3 support adjacent to the metal. Furthermore, the high activity of these sites was found to result from a hydrogen-bonded cyclic structure involving cooperativity between the phosphonate head group and CA tail function. More broadly, these results indicate that functional groups tethered to supports via organic ligands can influence catalytic chemistry on metal nanoparticles.

  1. Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin-Derived Model Phenolics.

    Science.gov (United States)

    Anderson, Eric; Crisci, Anthony; Murugappan, Karthick; Román-Leshkov, Yuriy

    2017-05-22

    Reductive catalytic fractionation of biomass has recently emerged as a powerful lignin extraction and depolymerization method to produce monomeric aromatic oxygenates in high yields. Here, bifunctional molybdenum-based polyoxometalates supported on titania (POM/TiO 2 ) are shown to promote tandem hydrodeoxygenation (HDO) and alkylation reactions, converting lignin-derived oxygenated aromatics into alkylated benzenes and alkylated phenols in high yields. In particular, anisole and 4-propylguaiacol were used as model compounds for this gas-phase study using a packed-bed flow reactor. For anisole, 30 % selectivity for alkylated aromatic compounds (54 % C-alkylation of the methoxy groups by methyl balance) with an overall 72 % selectivity for HDO at 82 % anisole conversion was observed over H 3 PMo 12 O 40 /TiO 2 at 7 h on stream. Under similar conditions, 4-propylguaiacol was mainly converted into 4-propylphenol and alkylated 4-propylphenols with a selectivity to alkylated 4-propylphenols of 42 % (77 % C-alkylation) with a total HDO selectivity to 4-propylbenzene and alkylated 4-propylbenzenes of 4 % at 92 % conversion (7 h on stream). Higher catalyst loadings pushed the 4-propylguaiacol conversion to 100 % and resulted in a higher selectivity to propylbenzene of 41 %, alkylated aromatics of 21 % and alkylated phenols of 17 % (51 % C-alkylation). The reactivity studies coupled with catalyst characterization revealed that Lewis acid sites act synergistically with neighboring Brønsted acid sites to simultaneously promote alkylation and hydrodeoxygenation activity. A reaction mechanism is proposed involving activation of the ether bond on a Lewis acid site, followed by methyl transfer and C-alkylation. Mo-based POMs represent a versatile catalytic platform to simultaneously upgrade lignin-derived oxygenated aromatics into alkylated arenes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Spectrophotometric method for determination of bifunctional macrocyclic ligands in macrocyclic ligand-protein conjugates

    International Nuclear Information System (INIS)

    Dadachova, E.; Chappell, L.L.; Brechbiel, M.W.

    1999-01-01

    A simple spectrophotometric assay for determination of bifunctional polyazacarboxylate-macrocyclic ligands of different sizes that are conjugated to proteins has been developed for: 12-membered macrocycle DOTA (2-[4-nitrobenzyl]-1, 4, 7, 10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) and analogs, the 15-membered PEPA macrocycle (2-[4-nitrobenzyl]-1,4,7,10,13-pentaazacyclopentadecane-N,N',N'',N''',N'''' -pentaacetic acid), and the large 18-membered macrocycle HEHA (1,4,7,10,13,16-hexaazacyclooctadecane-N,N',N'',N''',N''''-hexaacetic acid). The method is based on titration of the blue-colored 1:1 Pb(II)-Arsenazo III (AAIII) complex with the polyazacarboxylate macrocyclic ligand in the concentration range of 0-2.5 μM, wherein color change occurring upon transchelation of the Pb(II) from the AAIII to the polyazamacrocyclic ligand is monitored at 656 nm. The assay is performed at ambient temperature within 20 min without any interfering interaction between the protein and Pb(II)-AA(III) complex. Thus, this method also provides a ligand-to-protein ratio (L/P ratio) that reflects the effective number of ligands per protein molecule available to radiolabeling. The method is not suitable for 14-membered TETA macrocycle (2-[4-nitrobenzyl]-1, 4, 8, 11-tetraazacyclotetradecane N,N',N'',N'''-tetraacetic acid) because of low stability constant of Pb(II)-TETA complex. The method is rapid, simple and may be customized for other polyazacarboxylate macrocyclic ligands

  3. A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions

    Science.gov (United States)

    Zhang, Jintao; Zhao, Zhenghang; Xia, Zhenhai; Dai, Liming

    2015-05-01

    The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out with noble metals (such as Pt) and metal oxides (such as RuO2 and MnO2) as catalysts, respectively. However, these metal-based catalysts often suffer from multiple disadvantages, including high cost, low selectivity, poor stability and detrimental environmental effects. Here, we describe a mesoporous carbon foam co-doped with nitrogen and phosphorus that has a large surface area of ˜1,663 m2 g-1 and good electrocatalytic properties for both ORR and OER. This material was fabricated using a scalable, one-step process involving the pyrolysis of a polyaniline aerogel synthesized in the presence of phytic acid. We then tested the suitability of this N,P-doped carbon foam as an air electrode for primary and rechargeable Zn-air batteries. Primary batteries demonstrated an open-circuit potential of 1.48 V, a specific capacity of 735 mAh gZn-1 (corresponding to an energy density of 835 Wh kgZn-1), a peak power density of 55 mW cm-2, and stable operation for 240 h after mechanical recharging. Two-electrode rechargeable batteries could be cycled stably for 180 cycles at 2 mA cm-2. We also examine the activity of our carbon foam for both OER and ORR independently, in a three-electrode configuration, and discuss ways in which the Zn-air battery can be further improved. Finally, our density functional theory calculations reveal that the N,P co-doping and graphene edge effects are essential for the bifunctional electrocatalytic activity of our material.

  4. Novel configuration of bifunctional air electrodes for rechargeable zinc-air batteries

    Science.gov (United States)

    Li, Po-Chieh; Chien, Yu-Ju; Hu, Chi-Chang

    2016-05-01

    A novel configuration of two electrodes containing electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) pressed into a bifunctional air electrode is designed for rechargeable Zn-air batteries. MOC/25BC carbon paper (MOC consisting of α-MnO2 and XC-72 carbon black) and Fe0.1Ni0.9Co2O4/Ti mesh on this air electrode mainly serve as the cathode for the ORR and the anode for the OER, respectively. The morphology and physicochemical properties of Fe0.1Ni0.9Co2O4 are investigated through scanning electron microscopy, inductively coupled plasma-mass spectrometry, and X-ray diffraction. Electrochemical studies comprise linear sweep voltammetry, rotating ring-disk electrode voltammetry, and the full-cell charge-discharge-cycling test. The discharge peak power density of the Zn-air battery with the unique air electrode reaches 88.8 mW cm-2 at 133.6 mA cm-2 and 0.66 V in an alkaline electrolyte under an ambient atmosphere. After 100 charge-discharge cycles at 10 mA cm-2, an increase of 0.3 V between charge and discharge cell voltages is observed. The deep charge-discharge curve (10 h in each step) indicates that the cell voltages of discharge (1.3 V) and charge (1.97 V) remain constant throughout the process. The performance of the proposed rechargeable Zn-air battery is superior to that of most other similar batteries reported in recent studies.

  5. Facile preparation of Ag-Cu bifunctional electrocatalysts for zinc-air batteries

    International Nuclear Information System (INIS)

    Jin, Yachao; Chen, Fuyi

    2015-01-01

    Highlights: • Ag-Cu dendrites are observed for the first time to exhibit high catalytic activity for oxygen reduction reaction. • Ag-Cu dendrites are directly synthesized through galvanic displacement on the current collector layer made of Ni foams. • A bifunctional air cathode is fabricated using Ag-Cu dendrites as a carbon-free, binder-free catalyst layer. • Both the primary and rechargeable zinc–air batteries fabricated by Ag-Cu catalysts exhibit excellent performance. - ABSTRACT: An inexpensive, facile galvanic displacement reaction for the direct growth of silver–copper (Ag-Cu) catalysts on nickel foams is developed for the first time. The resulting Ag-Cu catalysts exhibit dendritic morphologies. Ag and Cu atoms are in their metallic state while the presence of CuO and Cu 2 O are limited on the surface of catalyst. The catalysts demonstrate high catalytic activity for oxygen reduction reaction (ORR) in alkaline solution, as evaluated by both linear scanning voltammetry and rotating disk electrode polarization measurements. The ORR catalysed by Ag-Cu catalyst in alkaline solution proceeds through a four-electron pathway. An air cathode is fabricated using Ag-Cu catalyst as a carbon-free, binder-free catalyst layer. Using this Ag-Cu catalyst based air cathode, both the primary and rechargeable zinc-air batteries show excellent battery performance. The specific capacity of the primary zinc-air battery is 572 mAh g −1 . Especially, the rechargeable zinc-air battery shows high round-trip efficiency, appealing stability at a long charge-discharge cycle period

  6. Characterization of a bifunctional glyoxylate cycle enzyme, malate synthase/isocitrate lyase, of Euglena gracilis.

    Science.gov (United States)

    Nakazawa, Masami; Nishimura, Masaaki; Inoue, Kengo; Ueda, Mitsuhiro; Inui, Hiroshi; Nakano, Yoshihisa; Miyatake, Kazutaka

    2011-01-01

    The glyoxylate cycle is a modified form of the tricarboxylic acid cycle, which enables organisms to synthesize carbohydrates from C2 compounds. In the protozoan Euglena gracilis, the key enzyme activities of the glyoxylate cycle, isocitrate lyase (ICL) and malate synthase (MS), are conferred by a single bifunctional protein named glyoxylate cycle enzyme (Euglena gracilis glyoxylate cycle enzyme [EgGCE]). We analyzed the enzymatic properties of recombinant EgGCE to determine the functions of its different domains. The 62-kDa N-terminal domain of EgGCE was sufficient to provide the MS activity as expected from an analysis of the deduced amino acid sequence. In contrast, expression of the 67-kDa C-terminal domain of EgGCE failed to yield ICL activity even though this domain was structurally similar to ICL family enzymes. Analyses of truncation mutants suggested that the N-terminal residues of EgGCE are critical for both the ICL and MS activities. The ICL activity of EgGCE increased in the presence of micro-molar concentrations of acetyl-coenzyme A (CoA). Acetyl-CoA also increased the activity in a mutant type EgGCE with a mutation at the acetyl-CoA binding site in the MS domain of EgGCE. This suggests that acetyl-CoA regulates the ICL reaction by binding to a site other than the catalytic center of the MS reaction. © 2011 The Author(s). Journal of Eukaryotic Microbiology© 2011 International Society of Protistologists.

  7. Crystal structure of two new bifunctional nonsubstrate type thrombin inhibitors complexed with human alpha-thrombin.

    Science.gov (United States)

    Féthière, J; Tsuda, Y; Coulombe, R; Konishi, Y; Cygler, M

    1996-06-01

    The crystal structures of two new thrombin inhibitors, P498 and P500, complexed with human alpha-thrombin have been determined at 2.0 A resolution and refined to crystallographic R-factors of 0.170 and 0.169, respectively. These compounds, with picomolar binding constants, belong to a family of potent bifunctional inhibitors that bind thrombin at two remote sites: the active site and the fibrinogen recognition exosite (FRE). The inhibitors incorporate a nonsubstrate type active site binding fragment: Dansyl-Arg-(D)Pipecolic acid (Dns-Arg-(D)Pip), reminiscent of the active-site directed inhibitors MD-805 and MQPA, rendering them resistant to thrombin-induced hydrolysis. The FRE binding fragment of these inhibitors corresponds to the hirudin55-65 sequence. They differ in the chemical nature of the nonpeptidyl linker bridging these two functional activities. In both cases, the active site binding fragment is well defined in the electron density. The DnsH1, ArgH2, and (D)PipH3 groups occupy the S3, S1, and S2 subsites of thrombin, respectively, in a way similar to that observed in the thrombin-MQPA complexes. Binding in the active site of thrombin is characterized by numerous van der Waals contacts and ring-ring system interactions. Unlike in the substrate-like inhibitors, ArgH2 enters the S1 specificity pocket from the P2 position and adopts a bent conformation to make an hydrogen bond to the carboxylate of Asp189. In this noncanonical position, its carbonyl points away from the oxyanion hole, which is now occupied by well-ordered solvent molecules. The linkers fit in the groove extending from the active site to the FRE. The C-terminal fragments of both inhibitors bind in the same way as analogous FRE binding elements in previously described complexes.

  8. Molecular Evolution and Functional Characterization of a Bifunctional Decarboxylase Involved in Lycopodium Alkaloid Biosynthesis1[OPEN

    Science.gov (United States)

    Bunsupa, Somnuk; Hanada, Kousuke; Maruyama, Akira; Aoyagi, Kaori; Komatsu, Kana; Ueno, Hideki; Yamashita, Madoka; Sasaki, Ryosuke; Oikawa, Akira; Yamazaki, Mami

    2016-01-01

    Lycopodium alkaloids (LAs) are derived from lysine (Lys) and are found mainly in Huperziaceae and Lycopodiaceae. LAs are potentially useful against Alzheimer’s disease, schizophrenia, and myasthenia gravis. Here, we cloned the bifunctional lysine/ornithine decarboxylase (L/ODC), the first gene involved in LA biosynthesis, from the LA-producing plants Lycopodium clavatum and Huperzia serrata. We describe the in vitro and in vivo functional characterization of the L. clavatum L/ODC (LcL/ODC). The recombinant LcL/ODC preferentially catalyzed the decarboxylation of l-Lys over l-ornithine (l-Orn) by about 5 times. Transient expression of LcL/ODC fused with the amino or carboxyl terminus of green fluorescent protein, in onion (Allium cepa) epidermal cells and Nicotiana benthamiana leaves, showed LcL/ODC localization in the cytosol. Transgenic tobacco (Nicotiana tabacum) hairy roots and Arabidopsis (Arabidopsis thaliana) plants expressing LcL/ODC enhanced the production of a Lys-derived alkaloid, anabasine, and cadaverine, respectively, thus, confirming the function of LcL/ODC in plants. In addition, we present an example of the convergent evolution of plant Lys decarboxylase that resulted in the production of Lys-derived alkaloids in Leguminosae (legumes) and Lycopodiaceae (clubmosses). This convergent evolution event probably occurred via the promiscuous functions of the ancestral Orn decarboxylase, which is an enzyme involved in the primary metabolism of polyamine. The positive selection sites were detected by statistical analyses using phylogenetic trees and were confirmed by site-directed mutagenesis, suggesting the importance of those sites in granting the promiscuous function to Lys decarboxylase while retaining the ancestral Orn decarboxylase function. This study contributes to a better understanding of LA biosynthesis and the molecular evolution of plant Lys decarboxylase. PMID:27303024

  9. Modification of bifunctional epoxy resin using CO2 fixation process and nanoclay

    International Nuclear Information System (INIS)

    Khoshkish, Morteza; Bouhendi, Hosein; Vafayan, Mehdi

    2014-01-01

    A bifunctional epoxy resin was modified by using a CO 2 fixation solution process in the presence of tetra n-butyl ammonium bromide (TBAB) as catalyst and the modified treated resin was treated by cloisite 30B as nano additive. The Unmodified epoxy resin (UME), CO 2 fixated modified epoxy resin (CFME), and CFME/clay nano composite (CFMEN), were cured by diethylenetriamine (DETA). A cycloaliphatic compound as a reactive diluent was used to control the viscosity of high viscose CFME. The exfoliation of organoclay in UME and CFME was investigated by X-ray diffraction and activation energy was computed using the advanced integral isoconversional method. The activation energy dependency demonstrated that the mechanism of UME curing did not change in the presence of nanoclay. In contrast, the CO 2 fixation results showed a significant change in the activation energy dependency. The Thermal stability parameters include the initial degradation temperature (IDT), the temperature at the maximum rate of weight loss (T max ), and the decomposition activation energy (E d ) were determined by thermal gravimetry analysis. Dynamic mechanical thermal analysis measurements showed that the presence of organoclay in CFME increases the T g of nano composite in contrast to UME. The fracture roughness of UME, CFME and CFNE were determined by scanning electron microscope. The exfoliated UME/1%clay nanocomposite was confirmed by TEM image. - Highlights: • A new epoxy resin was synthesized using CO 2 fixation reaction. • The synthesized epoxy resin was modified by an organo nano-clay. • CO 2 fixation noticeably changed the curing mechanism. • CO 2 fixation reaction consumes CO 2 which is a harmful greenhouse gas

  10. 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 ...

  11. Use of organometallic chelates in broiler diet: effect on the performance and bone structure. Preliminary results

    Directory of Open Access Journals (Sweden)

    Biagina Chiofalo

    2010-01-01

    Full Text Available On 26,000 Ross 508 broiler chickens (two groups of 13,000 per pen the effect of dietary substitution with in organic trace minerals or organometallic chelates on performances and bones tructure c trace minerals or organometallic chelates on performances and bone structure was studied. Treatments consisted of a commercial diet integrated with 0.5% of a vitamin-mineral premix containing inorganic trace minerals (CTR or organometallic chelates (MHA using Methionine Hydroxy Analog. Production performance was measured during the 52 d trial period and bone structure was evalu- ated at the slaughter (52 d. Significant (P=0.038 higher values were observed in the finishing period (41 to 52 d for the body weight of the treated group (3560 g vs. 3358 g. The same trend was observed for the ADG (MHA 87.6 g/d vs. CTR 71 g/d; P<0.05. Concerning ash percentage significant higher values were observed in the CTR group for femur (49.01% vs. 51.45%; P<0.01 and tibia (53.87% vs. 49.79%; P<0.001; femur showed also higher values for bone radiopacity (MHA 0.21 px vs. CTR 0.26 px; P=0.035. MHA group showed significant higher value for morphometric measures of the femur and tibia. Results suggest that organometallic chelates can be included in the diet without compromising broiler performance.

  12. 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...

  13. C,N-Chelated Organotin(IV) Azides: Synthesis, Structure and Use within the Click Chemistry.

    Czech Academy of Sciences Publication Activity Database

    Švec, P.; Bartoš, K.; Růžičková, Z.; Cuřínová, Petra; Dušek, L.; Turek, J.; de Proft, F.; Růžička, A.

    2016-01-01

    Roč. 40, č. 7 (2016), s. 5808-5817 ISSN 1144-0546 Grant - others:FWO(BE) 12T6615N Institutional support: RVO:67985858 Keywords : organotin(IV) azides * click chemistry * chelation Subject RIV: CC - Organic Chemistry Impact factor: 3.269, year: 2016

  14. 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

  15. Molecular characterization of whey protein hydrolysate fractions with ferrous chelating and enhanced iron solubility capabilities.

    Science.gov (United States)

    O'Loughlin, Ian B; Kelly, Phil M; Murray, Brian A; FitzGerald, Richard J; Brodkorb, Andre

    2015-03-18

    The ferrous (Fe2+) chelating capabilities of WPI hydrolysate fractions produced via cascade membrane filtration were investigated, specifically 1 kDa permeate (P) and 30 kDa retentate (R) fractions. The 1 kDa-P possessed a Fe2+ chelating capability at 1 g L(-1) equivalent to 84.4 μM EDTA (for 30 kDa-R the value was 8.7 μM EDTA). Fourier transformed infrared (FTIR) spectroscopy was utilized to investigate the structural characteristics of hydrolysates and molecular interactions with Fe2+. Solid-phase extraction was employed to enrich for chelating activity; the most potent chelating fraction was enriched in histidine and lysine. The solubility of ferrous sulfate solutions (10 mM) over a range of pH values was significantly (Piron solubility was improved by 72% in the presence of the 1 kDa-P fraction following simulated gastrointestinal digestion (SGID) compared to control FeSO4·7H2O solutions.

  16. Luminescent solutions and films of new europium complexes with chelating ligands

    Science.gov (United States)

    Kharcheva, Anastasia V.; Ivanov, Alexey V.; Borisova, Nataliya E.; Kaminskaya, Tatiana P.; Patsaeva, Svetlana V.; Popov, Vladimir V.; Yuzhakov, Viktor I.

    2015-03-01

    The development of new complexes of rare earth elements (REE) with chelating organic ligands opens up the possibility of purposeful alteration in the composition and structure of the complexes, and therefore tuning their optical properties. New ligands possessing two pyridine rings in their structure were synthesized to improve coordination properties and photophysical characteristics of REE compounds. Complexes of trivalent europium with novel chelating ligands were investigated using luminescence and absorption spectroscopy, as well as atomic force microscopy. Luminescence properties of new compounds were studied both for solutions and films deposited on the solid support. All complexes exhibit the characteristic red luminescence of Eu (III) ion with the absolute lumenescence quantum yield in polar acetonitrile solution varying from 0.21 to 1.45 % and emission lifetime ranged from 0.1 to 1 ms. Excitation spectra of Eu coordination complexes correspond with absorption bands of chelating ligand. The energy levels of the triplet state of the new ligands were determined from the phosphorescence at 77 K of the corresponding Gd (III) complexes. The morphology of films of europium complexes with different substituents in the organic ligands was investigated by atomic force microscopy (AFM). It strongly depends both on the type of substituent in the organic ligand, and the rotation speed of the spin-coater. New europium complexes with chelating ligands containing additional pyridine fragments represent outstanding candidates for phosphors with improved luminescence properties.

  17. Modeling the effect of succimer (DMSA; dimercaptosuccinic acid) chelation therapy in patients poisoned by lead

    NARCIS (Netherlands)

    van Eijkeren, Jan C H; Olie, J. Daniël N; Bradberry, Sally M; Vale, J Allister; de Vries, Irma|info:eu-repo/dai/nl/41398625X; Clewell, Harvey J.; Meulenbelt, Jan; Hunault, Claudine C|info:eu-repo/dai/nl/297757849

    CONTEXT: Kinetic models could assist clinicians potentially in managing cases of lead poisoning. Several models exist that can simulate lead kinetics but none of them can predict the effect of chelation in lead poisoning. Our aim was to devise a model to predict the effect of succimer

  18. Subcritical wet air oxidation of organic solvents and chelating agents of the nuclear fuel

    International Nuclear Information System (INIS)

    Bachir, Souley

    1999-01-01

    This document deals with the environment control, more specially organic solvents and chelating agents destruction, employed in the nuclear industry. This work details the subcritical wet air oxidation process. Another part of the document deals with the possible coupling between this process and the biodegradation technic in the framework of the sewage sludges treatment. (A.L.B.)

  19. Design and Application of Latent Olefin Metathesis Catalysts Featuring S-Chelating Alkylidene Ligands

    Science.gov (United States)

    Szadkowska, Anna; Grela, Karol

    This review article is devoted to recent advances in the design and application of so-called “dormant” or “latent” ruthenium olefin metathesis catalysts bearing S-chelating alkylidene ligands. Selected ruthenium complexes containing S-donor ligands, which possess controllable initiation behaviour are presented. Applications of these complexes in olefin metathesis are described.

  20. Chelation of lead by dimercaptopropane sulfonate and a possible diagnostic use.

    Science.gov (United States)

    Twarog, T; Cherian, M G

    1984-03-15

    The mobilization of lead (Pb) from Pb-exposed rats was examined following administration of dimercaptopropane sulfonate (DMPS). A dose-response study showed that the highest dose of DMPS (200 mumol/kg, ip) removed Pb from kidneys, liver, and bone, while the lower doses (25 and 50 mumol/kg) chelated Pb only from the kidneys. In experiments where DMPS was repeatedly injected to Pb-exposed rats, the maximum urinary excretion of Pb was observed within 24 hr after the first injection, with little effect in subsequent injections. Discontinuation of DMPS after the first injection (at a dose of 50 mumol DMPS/kg) caused renal Pb levels to increase until further injection of DMPS, several days later, which again mobilized Pb only from the kidneys. A single oral administration of 150 mumol DMPS/kg (a dose adjusted for specific chelation from the kidney) to rats, previously exposed to different doses of Pb resulted in a significant decrease of renal Pb in groups injected with more than 0.5 mg Pb/kg. A linear relationship was observed between renal Pb burden and urinary Pb excretion following chelation (r = 0.94, p less than 0.01). Thus, the specific removal of Pb from the kidney by DMPS treatment suggests a potential use of DMPS, a relatively nontoxic drug, for the estimation of renal Pb burden and also for treatment of Pb poisoning. Unlike other chelating agents, DMPS can be administered orally.

  1. 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 ...

  2. Chelating agents improve enzymatic solubilization of pectinaceous co-processing streams

    DEFF Research Database (Denmark)

    Ravn, Helle Christine; Meyer, Anne S.

    2014-01-01

    solubilization yields. The effect of the chelating agents correlated to their dissociation constants (pKa values) and calcium binding constants and citric acid and EDTA exerted highest effects. Maximum polysaccharide yield was obtained for FiberBind 400 where the enzymatic treatment in presence of citric acid...

  3. Iron chelation with deferasirox in a patient with de-novo ferroportin mutation.

    Science.gov (United States)

    Unal, Sule; Piperno, Alberto; Gumruk, Fatma

    2015-04-01

    Ferroportin disease is a rare type of autosomal dominantly inherited hemochromatosis caused with mutations in the ferroportin gene (SLC40A1). The patients characteristically have hyperferritinemia but normal transferin saturations. Herein, we present a 15-year-old female whose chief complaint was persistent nausea for the last one year. Extensive work-up including brain imaging revealed nothing to explain the etiology of nausea. The serum ferritin level of 1474ng/mL was suggestive for hemochromatosis syndromes and the molecular testing revealed de-novo c.485_487delTTG (P.Val162del) ferroportin gene mutation. Mild hepatic iron loading, in addition to the cumbersome nausea were accepted as indications for chelation treatment in this particular patient and deferasirox was initiated (10mg/kg/day) since family did not consent for phlebotomy. Deferasirox was stopped by the 9th month of initiation, since nausea subsided and hepatic iron content was normalized, in order to prevent over chelation. There are no well-established guidelines for the chelation of patients with hereditary hemochromatosis syndromes. However, lifelong monitorization for iron loading and re-initiation of chelation when necessary was planned in our patient. Copyright © 2015 Elsevier GmbH. All rights reserved.

  4. 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.

  5. Determination of proteins by a reverse biuret method combined with the copper-bathocuproine chelate reaction.

    Science.gov (United States)

    Matsushita, M; Irino, T; Komoda, T; Sakagishi, Y

    1993-07-16

    A method of protein determination has been developed which combines the biuret reaction and the copper(I)-bathocuproine chelate reaction. Protein in the specimen forms a Cu(2+)-protein chelate complex (biuret reaction) during the first step. Excess Cu2+ is reduced to Cu+ by ascrobic acid, allowing the Cu+ to form a Cu(+)-bathocuproine chelate complex during the second step. The amount of Cu(+)-bathocuproine chelate complex formed is inversely proportional to the protein concentration. The sensitivity (epsilon = 1.4 x 10(6) 1.mol-1.cm-1 against human albumin) of this method was higher than that of the original Lowry (9.8 x 10(5)), pyrogallol red (1.0 x 10(6)) and commercially available Coomassie Brilliant Blue G.250 methods (6.7 x 10(5)). The color intensities of human gamma-globulin, human globulin (fractions IV-1 and IV-4), bovine albumin, egg albumin and horse gamma-globulin against human albumin (100%) ranged from 92 to 101%. The results obtained with the present method (y) correlated well with those determined by the biuret method (r = 0.998, y = 0.98 chi - 0.002, x = 1.31, y = 1.29 g/l) in 30 diluted sera. These results confirm that this assay is similar in sensitivity to the original Lowry method, is rapid and has similar reactivity to each of the various proteins in biological fluids.

  6. 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.

  7. 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.

  8. 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.

  9. Searching for new aluminium chelating agents: a family of hydroxypyrone ligands.

    Science.gov (United States)

    Toso, Leonardo; Crisponi, Guido; Nurchi, Valeria M; Crespo-Alonso, Miriam; Lachowicz, Joanna I; Mansoori, Delara; Arca, Massimiliano; Santos, M Amélia; Marques, Sérgio M; Gano, Lurdes; Niclós-Gutíerrez, Juan; González-Pérez, Josefa M; Domínguez-Martín, Alicia; Choquesillo-Lazarte, Duane; Szewczuk, Zbigniew

    2014-01-01

    Attention is devoted to the role of chelating agents in the treatment of aluminium related diseases. In fact, in spite of the efforts that have drastically reduced the occurrence of aluminium dialysis diseases, they so far constitute a cause of great medical concern. The use of chelating agents for iron and aluminium in different clinical applications has found increasing attention in the last thirty years. With the aim of designing new chelators, we synthesized a series of kojic acid derivatives containing two kojic units joined by different linkers. A huge advantage of these molecules is that they are cheap and easy to produce. Previous works on complex formation equilibria of a first group of these ligands with iron and aluminium highlighted extremely good pMe values and gave evidence of the ability to scavenge iron from inside cells. On these bases a second set of bis-kojic ligands, whose linkers between the kojic chelating moieties are differentiated both in terms of type and size, has been designed, synthesized and characterized. The aluminium(III) complex formation equilibria studied by potentiometry, electrospray ionization mass spectroscopy (ESI-MS), quantum-mechanical calculations and (1)H NMR spectroscopy are here described and discussed, and the structural characterization of one of these new ligands is presented. The in vivo studies show that these new bis-kojic derivatives induce faster clearance from main organs as compared with the monomeric analog. © 2013.

  10. Chelating extractants of improved selectivity. Progress report for period November 1, 1977--July 31 1978

    International Nuclear Information System (INIS)

    Freiser, H.

    1978-08-01

    During the current contract period, the high susceptibility of lanthanide chelate stability to steric hindrance was confirmed. The increase in coordination number of lanthanides from lanthanum to ytterbium as evidenced from extraction equilibria serves to increase their separability. 8-Quinolinol immobilized on silica can separate lanthanide ions

  11. f-Element Ion Chelation in Highly Basic Media - Final Report

    International Nuclear Information System (INIS)

    Paine, R.T.

    2000-01-01

    A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelator s for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

  12. f-Element Ion Chelation in Highly Basic Media - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Paine, R.T.

    2000-12-12

    A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelator s for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

  13. 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).

  14. 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

  15. Sequence diversity and enzyme activity of ferric-chelate reductase LeFRO1 in tomato.

    Science.gov (United States)

    Kong, Danyu; Chen, Chunlin; Wu, Huilan; Li, Ye; Li, Junming; Ling, Hong-Qing

    2013-11-20

    Ferric-chelate reductase which functions in the reduction of ferric to ferrous iron on root surface is a critical protein for iron homeostasis in strategy I plants. LeFRO1 is a major ferric-chelate reductase involved in iron uptake in tomato. To identify the natural variations of LeFRO1 and to assess their effect on the ferric-chelate reductase activity, we cloned the coding sequences of LeFRO1 from 16 tomato varieties collected from different regions, and detected three types of LeFRO1 (LeFRO1(MM), LeFRO1(Ailsa) and LeFRO1(Monita)) with five amino acid variations at the positions 21, 24, 112, 195 and 582. Enzyme activity assay revealed that the three types of LeFRO1 possessed different ferric-chelate reductase activity (LeFRO1(Ailsa) > LeFRO1(MM) > LeFRO1(Monita)). The 112th amino acid residue Ala of LeFRO1 is critical for maintaining the high activity of ferric-chelate reductase, because modification of this amino acid resulted in a significant reduction of enzyme activity. Further, we showed that the combination of the amino acid residue Ile at the site 24 with Lys at the site 582 played a positive role in the enzyme activity of LeFRO1. In conclusion, the findings are helpful to understand the natural adaptation mechanisms of plants to iron-limiting stress, and may provide new knowledge to select and manipulate LeFRO1 for improving the iron deficiency tolerance in tomato. Copyright © 2013. Published by Elsevier Ltd.

  16. 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.

  17. 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.

  18. 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.

  19. Characterization of amorphous yttria layers deposited by aqueous solutions of Y-chelate alkoxides complex

    Science.gov (United States)

    Kim, Young-Soon; Lee, Yu-Ri; Kim, Byeong-Joo; Lee, Jae-Hun; Moon, Seung-Hyun; Lee, Hunju

    2015-01-01

    Crack-free amorphous yttria layers were deposited by dip coating in solutions of different Y-chelate alkoxides complex. Three Y-chelate solutions of different concentrations were prepared using yttrium acetate tetrahydrate, yttrium stearic acid as Y source materials. PEG, diethanolamine were used as chelating agents, while ethanol, methanol and tetradecane were used as solvent. Three different combinations of chelating and solvents were used to prepare solutions for Y2O3 dip coating on SUS, electropolished and non-electropolished Hastelloy C-276 substrates. The thickness of the films was varied by changing the number of dipping cycles. At an optimized condition, the substrate surface roughness (rms) value was reduced from ∼50 nm to ∼1 nm over a 10 × 10 μm2 area. After Y2O3 deposition, MgO was deposited using ion-beam assisted deposition (IBAD), then LaMnO3 (LMO) was deposited using sputtering and GdBCO was deposited using reactive co-evaporation by deposition and reaction (RCE-DR). Detailed X-ray study indicates that LMO/MgO/Y2O3 and GdBCO/LMO/MgO/Y2O3 stack films have good out-of-plane and in-plane textures with strong c-axis alignment. The critical current (Ic) of GdBCO/LMO/MgO/Y2O3 multilayer structure varied from 190 to 420 A/cm with different solutions, when measured at 77 K. These results demonstrated that amorphous yttria can be easily deposited by dip coating using Y-chelates complex as a diffusion barrier and nucleation layer.

  20. 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.

  1. Preparation of highly hydrophobic cotton fabrics by modification with bifunctional silsesquioxanes in the sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Przybylak, Marcin, E-mail: marcin.przybylak@ppnt.poznan.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland); Maciejewski, Hieronim, E-mail: maciejm@amu.edu.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland); Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań (Poland); Dutkiewicz, Agnieszka, E-mail: agdut@interia.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland)

    2016-11-30

    Highlights: • Fabric hydrophobization process using bifunctional silsesquioxanes was studied. • Superhydrophobic fabric was produced using fluorofunctional silsesquioxanes. • Surface of modified fabrics was analyzed using different techniques. - Abstract: The surface modification of cotton fabrics was carried out using two types of bifunctional fluorinated silsesquioxanes with different ratios of functional groups. The modification was performed either by one- or two-step process. Two methods, the sol-gel and the dip coating method were used in different configurations. The heat treatment and the washing process were applied after modification. The wettability of cotton fabric was evaluated by measuring water contact angles (WCA). Changes in the surface morphology were examined by scanning electron microscopy (SEM, SEM-LFD) and atomic force microscopy (AFM). Moreover, the modified fabrics were subjected to analysis of elemental composition of the applied coatings using SEM-EDS techniques. Highly hydrophobic textiles were obtained in all cases studied and one of the modifications resulted in imparting superhydrophobic properties. Most of impregnated textiles remained hydrophobic even after multiple washing process which shows that the studied modification is durable.

  2. Preparation of highly hydrophobic cotton fabrics by modification with bifunctional silsesquioxanes in the sol-gel process

    International Nuclear Information System (INIS)

    Przybylak, Marcin; Maciejewski, Hieronim; Dutkiewicz, Agnieszka

    2016-01-01

    Highlights: • Fabric hydrophobization process using bifunctional silsesquioxanes was studied. • Superhydrophobic fabric was produced using fluorofunctional silsesquioxanes. • Surface of modified fabrics was analyzed using different techniques. - Abstract: The surface modification of cotton fabrics was carried out using two types of bifunctional fluorinated silsesquioxanes with different ratios of functional groups. The modification was performed either by one- or two-step process. Two methods, the sol-gel and the dip coating method were used in different configurations. The heat treatment and the washing process were applied after modification. The wettability of cotton fabric was evaluated by measuring water contact angles (WCA). Changes in the surface morphology were examined by scanning electron microscopy (SEM, SEM-LFD) and atomic force microscopy (AFM). Moreover, the modified fabrics were subjected to analysis of elemental composition of the applied coatings using SEM-EDS techniques. Highly hydrophobic textiles were obtained in all cases studied and one of the modifications resulted in imparting superhydrophobic properties. Most of impregnated textiles remained hydrophobic even after multiple washing process which shows that the studied modification is durable.

  3. Synthesis and Characterization of Bifunctional Organic-Glasses Based on Diphenylhydrazone and Barbituric Acid Derivative for Photorefractive Application

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ki Hong [KIST, Seoul (Korea, Republic of); Lee, Sang Ho; Choi, Chil Sung; Kim, Nak Joong [Hanyang University, Seoul (Korea, Republic of); Choi, Dong Hoon [Kyunghee University, Youngin (Korea, Republic of)

    2003-12-15

    A series of amorphous molecules that possess both photoconductive and electro-optic properties was synthesized in order to investigate photorefractive properties of bifunctional organic-glasses. Diethylaminobenzaldehyde- diphenylhydrazone was covalently attached to 5-(4-diethylamino-benzylidene)-1,3-dimethylpyrimidine- 2,4,6-trione through a flexible alkyl chain (3, 4, 5, 6 and 10 carbons) containing two ether linkages. The longer linkage not only lowered the glass transition temperature (Tg) of the molecules, but also allowed faster orientation of the chromophore. To examine the photorefractive properties, a 50 μm-thick film was prepared from the mixture of a bifunctional molecule, butyl benzyl phthalate, and C{sup 60}. The photoconductivity of this composite was as high as 8.01 x 10{sup -12} S/cm at 60 V/μm, and the maximum diffraction efficiency (ηmax) of 50 μm-thick film was about 5% at 80 V/μm.

  4. Bifunctional cis-Abienol Synthase from Abies balsamea Discovered by Transcriptome Sequencing and Its Implications for Diterpenoid Fragrance Production*

    Science.gov (United States)

    Zerbe, Philipp; Chiang, Angela; Yuen, Macaire; Hamberger, Björn; Hamberger, Britta; Draper, Jason A.; Britton, Robert; Bohlmann, Jörg

    2012-01-01

    The labdanoid diterpene alcohol cis-abienol is a major component of the aromatic oleoresin of balsam fir (Abies balsamea) and serves as a valuable bioproduct material for the fragrance industry. Using high-throughput 454 transcriptome sequencing and metabolite profiling of balsam fir bark tissue, we identified candidate diterpene synthase sequences for full-length cDNA cloning and functional characterization. We discovered a bifunctional class I/II cis-abienol synthase (AbCAS), along with the paralogous levopimaradiene/abietadiene synthase and isopimaradiene synthase, all of which are members of the gymnosperm-specific TPS-d subfamily. The AbCAS-catalyzed formation of cis-abienol proceeds via cyclization and hydroxylation at carbon C-8 of a postulated carbocation intermediate in the class II active site, followed by cleavage of the diphosphate group and termination of the reaction sequence without further cyclization in the class I active site. This reaction mechanism is distinct from that of synthases of the isopimaradiene- or levopimaradiene/abietadiene synthase type, which employ deprotonation reactions in the class II active site and secondary cyclizations in the class I active site, leading to tricyclic diterpenes. Comparative homology modeling suggested the active site residues Asp-348, Leu-617, Phe-696, and Gly-723 as potentially important for the specificity of AbCAS. As a class I/II bifunctional enzyme, AbCAS is a promising target for metabolic engineering of cis-abienol production. PMID:22337889

  5. A novel bifunctional hybrid with marine bacterium alkaline phosphatase and Far Eastern holothurian mannan-binding lectin activities.

    Directory of Open Access Journals (Sweden)

    Larissa Balabanova

    Full Text Available A fusion between the genes encoding the marine bacterium Cobetia marina alkaline phosphatase (CmAP and Far Eastern holothurian Apostichopus japonicus mannan-binding C-type lectin (MBL-AJ was performed. Expression of the fusion gene in E. coli cells resulted in yield of soluble recombinant chimeric protein CmAP/MBL-AJ with the high alkaline phosphatase activity and specificity of the lectin MBL-AJ. The bifunctional hybrid CmAP/MBL-AJ was produced as a dimer with the molecular mass of 200 kDa. The CmAP/MBL-AJ dimer model showed the two-subunit lectin part that is associated with two molecules of alkaline phosphatase functioning independently from each other. The highly active CmAP label genetically linked to MBL-AJ has advantaged the lectin-binding assay in its sensitivity and time. The double substitution A156N/F159K in the lectin domain of CmAP/MBL-AJ has enhanced its lectin activity by 25 ± 5%. The bifunctional hybrid holothurian's lectin could be promising tool for developing non-invasive methods for biological markers assessment, particularly for improving the MBL-AJ-based method for early detection of a malignant condition in cervical specimens.

  6. MOF-Derived Ultrathin Cobalt Phosphide Nanosheets as Efficient Bifunctional Hydrogen Evolution Reaction and Oxygen Evolution Reaction Electrocatalysts

    Directory of Open Access Journals (Sweden)

    Hong Li

    2018-02-01

    Full Text Available The development of a highly efficient and stable bifunctional electrocatalyst for water splitting is still a challenging issue in obtaining clean and sustainable chemical fuels. Herein, a novel bifunctional catalyst consisting of 2D transition-metal phosphide nanosheets with abundant reactive sites templated by Co-centered metal−organic framework nanosheets, denoted as CoP-NS/C, has been developed through a facile one-step low-temperature phosphidation process. The as-prepared CoP-NS/C has large specific surface area and ultrathin nanosheets morphology providing rich catalytic active sites. It shows excellent electrocatalytic performances for hydrogen evolution reaction (HER and oxygen evolution reaction (OER in acidic and alkaline media, with the Tafel slopes of 59 and 64 mV/dec and a current density of 10 mA/cm2 at the overpotentials of 140 and 292 mV, respectively, which are remarkably superior to those of CoP/C, CoP particles, and comparable to those of commercial noble-metal catalysts. In addition, the CoP-NS/C also shows good durability after a long-term test.

  7. MOF-Derived Ultrathin Cobalt Phosphide Nanosheets as Efficient Bifunctional Hydrogen Evolution Reaction and Oxygen Evolution Reaction Electrocatalysts.

    Science.gov (United States)

    Li, Hong; Ke, Fei; Zhu, Junfa

    2018-02-07

    The development of a highly efficient and stable bifunctional electrocatalyst for water splitting is still a challenging issue in obtaining clean and sustainable chemical fuels. Herein, a novel bifunctional catalyst consisting of 2D transition-metal phosphide nanosheets with abundant reactive sites templated by Co-centered metal-organic framework nanosheets, denoted as CoP-NS/C, has been developed through a facile one-step low-temperature phosphidation process. The as-prepared CoP-NS/C has large specific surface area and ultrathin nanosheets morphology providing rich catalytic active sites. It shows excellent electrocatalytic performances for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in acidic and alkaline media, with the Tafel slopes of 59 and 64 mV/dec and a current density of 10 mA/cm² at the overpotentials of 140 and 292 mV, respectively, which are remarkably superior to those of CoP/C, CoP particles, and comparable to those of commercial noble-metal catalysts. In addition, the CoP-NS/C also shows good durability after a long-term test.

  8. Evaluation of complexing properties of chelating agents for the bismuth-213; Evaluation des proprietes complexantes d`agents chelatants pour le bismuth-213

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, A.K.; Gestin, J.F.; Chatal, J.F.; Cherel, M.; Leboterff, J.; Faivre-Chauvet, A. [INSERM U463, Nantes (France)

    1997-12-31

    The bismuth-213 is an alpha- and beta-emitting radioelement of very short physical half-life (45 min) obtained by means of a ({sup 225}Ac-{sup 213}Bi) generator. Given its radiotoxicity, this element presents an interest in radioimmunotherapy (RIT). At present, the DTPA derivatives alone are used in radiolabelling of antibodies for RIT. This study presents the complexing properties of other chelates potentially usable to this goal. Four original chelating agents were synthesized in order to choose the families giving the best results in complexing the {sup 213}Bi: the tri-ethylene-tetra-amino-hexa-carboxylic acid (HETA), the 1, 4, 7, 10-tetra-aza-cyclo-dodecane-1, 4, 7, 10-tetraacetic- 1- Gly-L-p-nitro Phe-amide (DOTA-pept), the 1, 4, 8, 11-tetrakis [(S)-2 hydroxy-propyl]-1, 4, 8, 11-tetra-aza-cyclo-tetra-decane (THEOH), and the ethylenediamine di-acetate di-acetamide-bis-thiophenol (EDTA-TH). Given the physical characteristics of {sup 213}Bi and the goal of our research, the studies of complexation were conducted by C.C.M. on silica, in highly diluted solution, with fixed chelates-{sup 213}Bi incubation time (15 min), and variable temperature and concentrations. Analysis of the results have been done by means of a phosphor-imager by measuring the number of pixels associated to every chromatographic spot. The obtained results show that the poly-aza poly-carboxylic derivatives and poly-aza di-thio dicarboxylic derivatives are the only able ones to complex rapidly and quantitatively the {sup 213}Bi

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

    Science.gov (United States)

    DeAlba-Montero, I; Guajardo-Pacheco, Jesús; Morales-Sánchez, Elpidio; Araujo-Martínez, Rene; Loredo-Becerra, G M; Martínez-Castañón, Gabriel-Alejandro; Ruiz, Facundo; Compeán 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 M100-S25 January 2015). In the antibacterial activity assays copper ions and copper-EDTA chelates were included as references, so that copper-amino acids chelates can be particularly suitable for acting as an antibacterial agent, so they are excellent candidates for specific applications. Additionally, to confirm the antimicrobial mechanism on bacterial cells, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) was carried out. A significant enhanced antimicrobial activity and a specific strain were found for copper chelates over E. faecalis . Its results would eventually lead to better utilization of copper-amino acids chelate for specific application where copper nanoparticles can be not used.

  10. Iron Chelators and Antioxidants Regenerate Neuritic Tree and Nigrostriatal Fibers of MPP+/MPTP-Lesioned Dopaminergic Neurons.

    Directory of Open Access Journals (Sweden)

    Pabla Aguirre

    Full Text Available Neuronal death in Parkinson's disease (PD is often preceded by axodendritic tree retraction and loss of neuronal functionality. The presence of non-functional but live neurons opens therapeutic possibilities to recover functionality before clinical symptoms develop. Considering that iron accumulation and oxidative damage are conditions commonly found in PD, we tested the possible neuritogenic effects of iron chelators and antioxidant agents. We used three commercial chelators: DFO, deferiprone and 2.2'-dypyridyl, and three 8-hydroxyquinoline-based iron chelators: M30, 7MH and 7DH, and we evaluated their effects in vitro using a mesencephalic cell culture treated with the Parkinsonian toxin MPP+ and in vivo using the MPTP mouse model. All chelators tested promoted the emergence of new tyrosine hydroxylase (TH-positive processes, increased axodendritic tree length and protected cells against lipoperoxidation. Chelator treatment resulted in the generation of processes containing the presynaptic marker synaptophysin. The antioxidants N-acetylcysteine and dymetylthiourea also enhanced axodendritic tree recovery in vitro, an indication that reducing oxidative tone fosters neuritogenesis in MPP+-damaged neurons. Oral administration to mice of the M30 chelator for 14 days after MPTP treatment resulted in increased TH- and GIRK2-positive nigra cells and nigrostriatal fibers. Our results support a role for oral iron chelators as good candidates for the early treatment of PD, at stages of the disease where there is axodendritic tree retraction without neuronal death.

  11. Genetic evidence that induction of root Fe(III) chelate reductase activity is necessary for iron uptake under iron deficiency.

    Science.gov (United States)

    Yi, Y; Guerinot, M L

    1996-11-01

    Reduction of Fe(III) to Fe(II) by Fe(III) chelate reductase is thought to be an obligatory step in iron uptake as well as the primary factor in making iron available for absorption by all plants except grasses. Fe(III) chelate reductase has also been suggested to play a more general role in the regulation of cation absorption. In order to experimentally address the importance of Fe(III) chelate reductase activity in the mineral nutrition of plants, three Arabidopsis thaliana mutans (frd1-1, frd1-2 and frd1-3), that do not show induction of Fe(III) chelate reductase activity under iron-deficient growth conditions, have been isolated and characterized. These mutants are still capable of acidifying the rhizosphere under iron-deficiency and accumulate more Zn and Mn in their shoots relative to wild-type plants regardless of iron status. frd1 mutants do not translocate radiolabeled iron to the shoots when roots are presented with a tightly chelated form of Fe(III). These results: (1) confirm that iron must be reduced before it can be transported, (2) show that Fe(III) reduction can be uncoupled from proton release, the other major iron-deficiency response, and (3) demonstrate that Fe(III) chelate reductase activity per se is not necessarily responsible for accumulation of cations previously observed in pea and tomato mutants with constitutively high levels of Fe(III) chelate reductase activity.

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

    Directory of Open Access Journals (Sweden)

    Gloria Miller

    2008-12-01

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

  13. Steam reforming of acetic acid as a biomass derived oxygenate: Bifunctional pathway for hydrogen formation over Pt/ZrO2 catalysts.

    NARCIS (Netherlands)

    Takanabe, K.; Aika, Ken-ichi; Inazu, Koji; Baba, Toshihide; Seshan, Kulathuiyer; Lefferts, Leonardus

    2006-01-01

    Mechanistic studies on steam reforming of acetic acid over Pt/ZrO2 catalysts were performed as extension of our previous work [K. Takanabe, K. Aika, K. Seshan, L. Lefferts, J. Catal. 227 (2004) 101]. An overall picture of the bifunctional mechanism is established for steam reforming of acetic acid,

  14. Effects of thiourea and ammonium bicarbonate on the formation and stability of bifunctional cisplatin-DNA adducts : consequences for the accurate quantification of adducts in (cellular) DNA

    NARCIS (Netherlands)

    Fichtinger-Schepman, A.M.J.; Dijk-Knijnenburg, H.C.M. van; Dijt, F.J.; Velde-Visser, S.D. van der; Berends, F.; Baan, R.A.

    1995-01-01

    Cisplatin reacts with DNA by forming mainly bifunctional adducts via reactive monofunctional intermediates. When freshly platinated DNA was postincubated with thiourea (10 mM, at 23 or 37°C) for periods of up to 24 h, followed by determination of mono- and diadducts, a rapid initial decrease was

  15. Enantioselective Michael Addition of 3-Aryl-Substituted Oxindoles to Methyl Vinyl Ketone Catalyzed by a Binaphthyl-Modified Bifunctional Organocatalyst

    Directory of Open Access Journals (Sweden)

    Saet Byeol Woo

    2012-06-01

    Full Text Available The enantioselective conjugate addition reaction of 3-aryl-substituted oxindoles with methyl vinyl ketone promoted by binaphthyl-modified bifunctional organocatalysts was investigated. The corresponding Michael adducts, containing a quaternary center at the C3-position of the oxindoles, were generally obtained in high yields with excellent enantioselectivities (up to 91% ee.

  16. Parameter design and experimental study of a bifunctional isolator for optical payload protection and stabilization

    Science.gov (United States)

    Wang, Guang-yuan; Guan, Xin; Cao, Dong-jing; Tang, Shao-fan; Chen, Xiang; Liang, Lu; Zheng, Gang-tie

    2017-11-01

    With the raise of resolution, optical payloads are becoming increasingly sensitive to satellite jitter. An approach where the entire spacecraft is pointed with great accuracy requires sophisticated and expensive bus design. In an effort to lower the overall cost of space missions that require highly stable line-of-sight pointing, a method of separating the bus and the payload with low frequency isolators is proposed. This isolation system can block the transmission of disturbance and allow relatively large bus motion. However, if the isolator is linear then there is a trade-off between isolation and static deflection as the launch and the on-orbit stage have difference requirements on the isolation frequency. Otherwise, an extra locking system should be appended to protect the payload before getting into orbit, as the STABLE isolation system[1] and the MIM isolation system[2] did. To overcome this limitation, an alternative approach is to design a nonlinear isolator with high-static stiffness during launch and low dynamic stiffness on orbit. Several specially designed nonlinear isolators have achieved low dynamic stiffness with large static load capacity. Virgin[3] considered a structure made from a highly deformed elastic element to achieve a softening spring. Platus[4] exploited the buckling of beams under axial load in a specific configuration to achieve a negative stiffness in combination with a positive stiffness, and hence low-dynamic stiffness. Others have achieved the same by connecting linear springs with positive stiffness in parallel with elements of negative stiffness[5] [7]. In the present study, a bifunctional isolator has been developed for optical payloads. The isolator have good performance both during launch and on orbit because of its specially designed nonlinear stiffness and damping. The isolator works in a linear part with low stiffness and small damping ratio under the micro-vibration and microgravity on orbit. The transmissibility

  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. 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

  19. 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

  20. In vitro antimicrobial activity of hydroxypyridinone hexadentate-based dendrimeric chelators alone and in combination with norfloxacin.

    Science.gov (United States)

    Zhou, Ying-Jun; Zhang, Ming-Xia; Hider, Robert C; Zhou, Tao

    2014-06-01

    The antimicrobial activity of one 3-hydroxypyridin-4-one (HPO) hexadentate (1) and three HPO hexadentate-based dendrimeric chelators (2-4) was evaluated. They were found to exhibit marked inhibitory effect on the growth of two Gram-positive bacteria and two Gram-negative bacteria. The combination treatment of dendrimeric chelator 2 with norfloxacin against Staphyloccocus aureus and Escherichia coli showed a dramatic synergistic bactericidal effect. As the dendrimeric chelator has a large molecular weight, its combination with norfloxacin may find application in the treatment of external infections. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  1. Lanthanide chelate complementation and hydrolysis enhanced luminescent chelate in real-time reverse transcription polymerase chain reaction assays for KLK3 transcripts.

    Science.gov (United States)

    Alinezhad, Saeid; Väänänen, Riina-Minna; Lehmusvuori, Ari; Karhunen, Ulla; Soukka, Tero; Kähkönen, Esa; Taimen, Pekka; Alanen, Kalle; Pettersson, Kim

    2014-01-01

    The requirement for high-performance reporter probes in real-time detection of polymerase chain reaction (PCR) has led to the use of time-resolved fluorometry of lanthanide chelates. The aim of this study was to investigate the applicability of the principle of lanthanide chelate complementation (LCC) in comparison with a method based on hydrolysis enhancement and quenching of intact probes. A real-time reverse transcription (RT) PCR assay for kallikrein-related peptidase 3 (KLK3, model analyte) was developed by using the LCC detection method. Both detection methods were tested with a standard series of purified PCR products, 20 prostatic tissues, 20 healthy and prostate cancer patient blood samples, and female blood samples spiked with LNCaP cells. The same limit of detection was obtained with both methods, and two cycles earlier detection with the LCC method was observed. KLK3 messenger RNA (mRNA) was detected in all tissue samples and in 1 of 20 blood samples identically with both methods. The background was 30 times lower, and the signal-to-background (S/B) ratio was 3 times higher, when compared with the reference method. Use of the new reporter method provided similar sensitivity and specificity as the reference method. The lower background, the improved S/B ratio, and the possibility of melting curve analysis and single nucleotide polymorphism (SNP) detection could be advantages for this new reporter probe. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Copper-chelating azides for efficient click conjugation reactions in complex media.

    Science.gov (United States)

    Bevilacqua, Valentina; King, Mathias; Chaumontet, Manon; Nothisen, Marc; Gabillet, Sandra; Buisson, David; Puente, Céline; Wagner, Alain; Taran, Frédéric

    2014-06-02

    The concept of chelation-assisted copper catalysis was employed for the development of new azides that display unprecedented reactivity in the copper(I)-catalyzed azide-alkyne [3+2] cycloaddition (CuAAC) reaction. Azides that bear strong copper-chelating moieties were synthesized; these functional groups allow the formation of azide copper complexes that react almost instantaneously with alkynes under diluted conditions. Efficient ligation occurred at low concentration and in complex media with only one equivalent of copper, which improves the biocompatibility of the CuAAC reaction. Furthermore, such a click reaction allowed the localization of a bioactive compound inside living cells by fluorescence measurements. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Solution-processed Al-chelated gelatin for highly transparent non-volatile memory applications

    International Nuclear Information System (INIS)

    Chang, Yu-Chi; Wang, Yeong-Her

    2015-01-01

    Using the biomaterial of Al-chelated gelatin (ACG) prepared by sol-gel method in the ITO/ACG/ITO structure, a highly transparent resistive random access memory (RRAM) was obtained. The transmittance of the fabricated device is approximately 83% at 550 nm while that of Al/gelatin/ITO is opaque. As to the ITO/gelatin/ITO RRAM, no resistive switching behavior can be seen. The ITO/ACG/ITO RRAM shows high ON/OFF current ratio (>10 5 ), low operation voltage, good uniformity, and retention characteristics at room temperature and 85 °C. The mechanism of the ACG-based memory devices is presented. The enhancement of these electrical properties can be attributed to the chelate effect of Al ions with gelatin. Results show that transparent ACG-based memory devices possess the potential for next-generation resistive memories and bio-electronic applications

  4. Fusaric acid induces a notochord malformation in zebrafish via copper chelation.

    Science.gov (United States)

    Yin, Emily S; Rakhmankulova, Malika; Kucera, Kaury; de Sena Filho, Jose Guedes; Portero, Carolina E; Narváez-Trujillo, Alexandra; Holley, Scott A; Strobel, Scott A

    2015-08-01

    Over a thousand extracts were tested for phenotypic effects in developing zebrafish embryos to identify bioactive molecules produced by endophytic fungi. One extract isolated from Fusarium sp., a widely distributed fungal genus found in soil and often associated with plants, induced an undulated notochord in developing zebrafish embryos. The active compound was isolated and identified as fusaric acid. Previous literature has shown this phenotype to be associated with copper chelation from the active site of lysyl oxidase, but the ability of fusaric acid to bind copper ions has not been well described. Isothermal titration calorimetry revealed that fusaric acid is a modest copper chelator with a binding constant of 4.4 × 10(5) M(-1). These results shed light on the toxicity of fusaric acid and the potential teratogenic effects of consuming plants infected with Fusarium sp.

  5. 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.

  6. The Structural Basis of Action of Vanadyl (VO2+) Chelates in Cells.

    Science.gov (United States)

    Makinen, Marvin W; Salehitazangi, Marzieh

    2014-11-01

    Much emphasis has been given to vanadium compounds as potential therapeutic reagents for the treatment of diabetes mellitus. Thus far, no vanadium compound has proven efficacious for long-term treatment of this disease in humans. Therefore, in review of the research literature, our goal has been to identify properties of vanadium compounds that are likely to favor physiological and biochemical compatibility for further development as therapeutic reagents. We have, therefore, limited our review to those vanadium compounds that have been used in both in vivo experiments with small, laboratory animals and in in vitro studies with primary or cultured cell systems and for which pharmacokinetic and pharmacodynamics results have been reported, including vanadium tissue content, vanadium and ligand lifetime in the bloodstream, structure in solution, and interaction with serum transport proteins. Only vanadyl (VO 2+ ) chelates fulfill these requirements despite the large variety of vanadium compounds of different oxidation states, ligand structure, and coordination geometry synthesized as potential therapeutic agents. Extensive review of research results obtained with use of organic VO 2+ -chelates shows that the vanadyl chelate bis (acetylacetonato)oxidovanadium(IV) [hereafter abbreviated as VO(acac) 2 ], exhibits the greatest capacity to enhance insulin receptor kinase activity in cells compared to other organic VO 2+ -chelates, is associated with a dose-dependent capacity to lower plasma glucose in diabetic laboratory animals, and exhibits a sufficiently long lifetime in the blood stream to allow correlation of its dose-dependent action with blood vanadium content. The properties underlying this behavior appear to be its high stability and capacity to remain intact upon binding to serum albumin. We relate the capacity to remain intact upon binding to serum albumin to the requirement to undergo transcytosis through the vascular endothelium to gain access to target tissues

  7. Randomised controlled trials of iron chelators for the treatment of cardiac siderosis in thalassaemia major

    Directory of Open Access Journals (Sweden)

    Arun John Baksi

    2014-09-01

    Full Text Available In conditions requiring repeated blood transfusion or where iron metabolism is abnormal, heart failure may result from accumulation of iron in the heart (cardiac siderosis. Death due to heart failure from cardiac iron overload has accounted for considerable early mortality in β-thalassemia major. The ability to detect iron loading in the heart by cardiovascular magnetic resonance using T2* sequences has created an opportunity to intervene in the natural history of such conditions. However, effective and well tolerated therapy is required to remove iron from the heart. There are currently 3 approved commercially available iron chelators: deferoxamine, deferiprone and deferasirox. We review the high quality randomised controlled trials in this area for iron chelation therapy in the management of cardiac siderosis.

  8. On a mechanism of NPP steam generator cleaning using chelating agents

    International Nuclear Information System (INIS)

    Zverev, V.A.; Margulova, T.Kh.

    1984-01-01

    The experience of steam generator cleaning at the Novovoronezh NPP by means of chelating agents is briefly described. The cleaning process was carried out with the NPP being operative. Examination of surfaces after shutdown shows an essenial decrease in the surface fouling. The heat exchange surface of the steam generator is made of 08Kh18N10T austenitic stainless steel, and the reactor vessel-of pealitic steel. In-operation cleaning in the presence of two different steels consists in hematite removal from the 08Kh18N10T steel with the ferrum chelating agent formation and thermal decomposition of the latter in water and on the vessel pearlitic steel surface with the magnetite layer formation on it

  9. 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.

  10. 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

  11. Lutetium-177 and iodine-131 loaded chelating polymer microparticles intended for radioembolization of liver malignancies

    Czech Academy of Sciences Publication Activity Database

    Hrubý, Martin; Škodová, Michaela; Macková, Hana; Skopal, Jan; Tomeš, Marek; Kropáček, Martin; Zimová, Jana; Kučka, Jan

    2011-01-01

    Roč. 71, č. 12 (2011), s. 1155-1159 ISSN 1381-5148 R&D Projects: GA ČR GPP207/10/P054; GA MŠk 1M0505 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z10480505 Keywords : macroporous chelating beads * radioembolization * quinoline-8-ol Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.479, year: 2011

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2018-05-01

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

  13. 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.

  14. 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...

  15. Vanadium(IV) and -(V) Complexes with O,N-Chelating Aminophenolate and Pyridylalkoxide,

    NARCIS (Netherlands)

    Koten, G. van; Hagen, H.; Bezemer, C.; Boersma, J.; Kooijman, H.; Lutz, M.H.; Spek, A.L.

    2000-01-01

    Two different monoanionic O,N-chelating ligand systems, i.e., [OC6H2(CH2NMe2)-2-Me2-4,6]- (1) and [OCMe2([2]-Py)]- (2), have been applied in the synthesis of vanadium(V) complexes. The tertiary amine functionality in 1 caused reduction of the vanadium nucleus to the 4+ oxidation state with either

  16. Chelating polymeric beads as potential therapeutics for Wilson’s disease

    Czech Academy of Sciences Publication Activity Database

    Mattová, J.; Poučková, P.; Kučka, Jan; Škodová, Michaela; Vetrík, Miroslav; Štěpánek, Petr; Urbánek, P.; Petřík, M.; Nový, Z.; Hrubý, Martin

    2014-01-01

    Roč. 62, 1 October (2014), s. 1-7 ISSN 0928-0987 R&D Projects: GA ČR GAP304/12/0950; GA ČR GA13-08336S; GA MPO FR-TI4/625 Institutional support: RVO:61389013 Keywords : Wilson’s disease * polymer beads * chelators Subject RIV: CA - Inorganic Chemistry Impact factor: 3.350, year: 2014

  17. Switch from antagonist to agonist after addition of a DOTA chelator to a somatostatin analog

    International Nuclear Information System (INIS)

    Reubi, Jean Claude; Cescato, Renzo; Waser, Beatrice; Erchegyi, Judit; Rivier, Jean E.

    2010-01-01

    Peptide receptor targeting has become an increasingly attractive method to target tumors diagnostically and radiotherapeutically. Peptides linked to a variety of chelators have been developed for this purpose. They have, however, rarely been tested for their agonistic or antagonistic properties. We report here on a somatostatin antagonist that switched to an agonist upon coupling to a DOTA chelator. Two novel somatostatin analogs, 406-040-15 and its DOTA-coupled counterpart 406-051-20, with and without cold Indium labeling, were tested for their somatostatin receptor subtypes 1-5 (sst 1 -sst 5 ) binding affinity using receptor autoradiography. Moreover, they were tested functionally for their ability to affect sst 2 and sst 3 internalization in vitro in HEK293 cells stably expressing the human sst 2 or sst 3 receptor, using an immunofluorescence microscopy-based internalization assay. All three compounds were characterized as pan-somatostatin analogs having a high affinity for all five sst. In the sst 2 internalization assay, all three compounds showed an identical behavior, namely, a weak agonistic effect complemented by a weak antagonistic effect, compatible with the behavior of a partial agonist. Conversely, in the sst 3 internalization assay, 406-040-15 was a full antagonist whereas its DOTA-coupled counterpart, 406-051-20, with and without Indium labeling, switched to a full agonist. Adding the DOTA chelator to the somatostatin analog 406-040-15 triggers a switch at sst 3 receptor from an antagonist to an agonist. This indicates that potential radioligands for tumor targeting should always be tested functionally before further development, in particular if a chelator is added. (orig.)

  18. Characterization of FRO1, a Pea Ferric-Chelate Reductase Involved in Root Iron Acquisition1

    Science.gov (United States)

    Waters, Brian M.; Blevins, Dale G.; Eide, David J.

    2002-01-01

    To acquire iron, many plant species reduce soil Fe(III) to Fe(II) by Fe(III)-chelate reductases embedded in the plasma membrane of root epidermal cells. The reduced product is then taken up by Fe(II) transporter proteins. These activities are induced under Fe deficiency. We describe here the FRO1 gene from pea (Pisum sativum), which encodes an Fe(III)-chelate reductase. Consistent with this proposed role, FRO1 shows similarity to other oxidoreductase proteins, and expression of FRO1 in yeast conferred increased Fe(III)-chelate reductase activity. Furthermore, FRO1 mRNA levels in plants correlated with Fe(III)-chelate reductase activity. Sites of FRO1 expression in roots, leaves, and nodules were determined. FRO1 mRNA was detected throughout the root, but was most abundant in the outer epidermal cells. Expression was detected in mesophyll cells in leaves. In root nodules, mRNA was detected in the infection zone and nitrogen-fixing region. These results indicate that FRO1 acts in root Fe uptake and they suggest a role in Fe distribution throughout the plant. Characterization of FRO1 has also provided new insights into the regulation of Fe uptake. FRO1 expression and reductase activity was detected only in Fe-deficient roots of Sparkle, whereas both were constitutive in brz and dgl, two mutants with incorrectly regulated Fe accumulation. In contrast, FRO1 expression was responsive to Fe status in shoots of all three plant lines. These results indicate differential regulation of FRO1 in roots and shoots, and improper FRO1 regulation in response to a shoot-derived signal of iron status in the roots of the brz and dgl mutants. PMID:12011340

  19. Characterization of FRO1, a pea ferric-chelate reductase involved in root iron acquisition.

    Science.gov (United States)

    Waters, Brian M; Blevins, Dale G; Eide, David J

    2002-05-01

    To acquire iron, many plant species reduce soil Fe(III) to Fe(II) by Fe(III)-chelate reductases embedded in the plasma membrane of root epidermal cells. The reduced product is then taken up by Fe(II) transporter proteins. These activities are induced under Fe deficiency. We describe here the FRO1 gene from pea (Pisum sativum), which encodes an Fe(III)-chelate reductase. Consistent with this proposed role, FRO1 shows similarity to other oxidoreductase proteins, and expression of FRO1 in yeast conferred increased Fe(III)-chelate reductase activity. Furthermore, FRO1 mRNA levels in plants correlated with Fe(III)-chelate reductase activity. Sites of FRO1 expression in roots, leaves, and nodules were determined. FRO1 mRNA was detected throughout the root, but was most abundant in the outer epidermal cells. Expression was detected in mesophyll cells in leaves. In root nodules, mRNA was detected in the infection zone and nitrogen-fixing region. These results indicate that FRO1 acts in root Fe uptake and they suggest a role in Fe distribution throughout the plant. Characterization of FRO1 has also provided new insights into the regulation of Fe uptake. FRO1 expression and reductase activity was detected only in Fe-deficient roots of Sparkle, whereas both were constitutive in brz and dgl, two mutants with incorrectly regulated Fe accumulation. In contrast, FRO1 expression was responsive to Fe status in shoots of all three plant lines. These results indicate differential regulation of FRO1 in roots and shoots, and improper FRO1 regulation in response to a shoot-derived signal of iron status in the roots of the brz and dgl mutants.

  20. Flavonoids function as antioxidants: by scavenging reactive oxygen species or by chelating iron?

    Energy Technology Data Exchange (ETDEWEB)

    Wuguo Deng; Xingwang Fang; Jilan Wu [Peking Univ., Technical Physics Dept., Beijing (China)

    1997-09-01

    Flavonoids have been reported to exhibit strong antioxidative activity. In the present work, a systematic mechanistic study has been performed on five flavonoids (baicalin, hesperidin, naringin, quercetin and rutin) selected according to their structural characteristics. The experimental results reveal that flavonoids function as antioxidant mainly by chelating iron ions and by scavenging peroxyl radicals whereas their OH radical scavenging effect is much less important. (author).

  1. 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.

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

    OpenAIRE

    Engström, B

    1984-01-01

    The gastrointestinal absorption, transport, tissue deposition and excretion of cadmium was studied in adult male mice given a single oral LD50 dose of 109Cd-labeled CdCl2 alone or in combination with nitrilotriacetic acid (NTA), sodium tripolyphosphate (STPP) or ethylenediaminetetraacetic acid (EDTA). Blood, intestinal mucosa, liver and kidneys were analyzed for 109Cd at different times after exposure and the influence of the chelating agents on Cd binding to metallothionein and other tissue ...

  3. Safety and Outcomes of Open-Label Deferasirox Iron Chelation Therapy for Mucormycosis▿

    OpenAIRE

    Spellberg, Brad; Andes, David; Perez, Mario; Anglim, Anne; Bonilla, Hector; Mathisen, Glenn E.; Walsh, Thomas J.; Ibrahim, Ashraf S.

    2009-01-01

    We sought to describe the safety profile of open-label, adjunctive deferasirox iron chelation therapy in eight patients with biopsy-proven mucormycosis. Deferasirox was administered for an average of 14 days (range, 7 to 21) at 5 to 20 mg/kg of body weight/day. The only adverse effects attributable to deferasirox were rashes in two patients. Deferasirox treatment was not associated with changes in renal or liver function, complete blood count, or transplant immunosuppressive levels. Thus, def...

  4. CoMo/ZrO2 Hydrodesulfurization Catalysts Prepared by Chelating Agent Assisted Spreading

    Czech Academy of Sciences Publication Activity Database

    Kaluža, Luděk; Zdražil, Miroslav; Vít, Zdeněk; Gulková, Daniela

    2012-01-01

    Roč. 42, SI (2012), s. 261-266 E-ISSN 1877-7058. [International Congress of Chemical and Process Engineering CHISA 2012 and 15th Conference PRES 2012 /20./. Prague, 25.08.2012-29.08.2012] R&D Projects: GA ČR GAP106/11/0902 Institutional support: RVO:67985858 Keywords : chelating agent * catalyst preparation * ZrO2 supported catalyst s Subject RIV: CF - Physical ; Theoretical Chemistry

  5. Solution mining dawsonite from hydrocarbon containing formations with a chelating agent

    Science.gov (United States)

    Vinegar, Harold J [Bellaire, TX

    2009-07-07

    A method for treating an oil shale formation comprising dawsonite includes providing heat from one or more heaters to the formation to heat the formation. Hydrocarbon fluids are produced from the formation. At least some dawsonite in the formation is decomposed with the provided heat. A chelating agent is provided to the formation to dissolve at least some dawsonite decomposition products. The dissolved dawsonite decomposition products are produced from the formation.

  6. Preclinical evaluation of somatostatin analogs bearing two macrocyclic chelators for high specific activity labeling with radiometals

    International Nuclear Information System (INIS)

    Storch, D.; Schmitt, J.S.; Waldherr, C.; Maecke, H.R.; Waser, B.; Reubi, J.C.

    2007-01-01

    Radiometallated analogues of the regulatory peptide somatostatin are of interest in the in vivo localization and targeted radiotherapy of somatostatin receptor-overexpressing tumors. An important aspect of their use in vivo is a fast and efficient labeling (complexation) protocol for radiometals along with a high specific activity. We describe in this manuscript synthetic methods for the coupling of two chelators (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid = DOTA) to the bioactive peptide [Tyr 3 ,Thr 8 ]-octreotide (TATE) in order to increase the specific activity (radioactivity in Bq per mole peptide). The full chelator-linker-peptide conjugate was assembled on solid support using standard Fmoc chemistry. Two DOTA-chelators were linked to the peptide using lysine or N,N'-bis(3-aminopropyl)-glycine (Apg); in addition, pentasarcosine (Sar 5 ) was used as a spacer between the chelators and the peptide to probe its influence on biology and pharmacology. Complexation rates with In 3+ and Y 3+ salts and the corresponding radiometals were high, the bis-DOTA-derivatives showed higher complexation rates and gave higher specific activity than DOTA-TATE. Pharmacological and biological data of the complexed molecules did not show significant differences if compared to the parent peptide [ 111/nat In-DOTA]-TATE except for [( 111/nat In-DOTA) 2 -Apg]-TATE which showed a lower binding affinity and rate of internalization into tumor cells. The biodistribution of [( 111/nat In-DOTA)-Lys( 111/nat In-DOTA)]-TATE in the rat tumor model (AR4-2J) showed a high and specific (as shown by a blocking experiment) tracer uptake in somatostatin receptor-positive tissue but a lower tumor uptake compared to [ 111/nat In-DOTA]-TATE. (orig.)

  7. Development of bifunctional microencapsulated phase change materials with crystalline titanium dioxide shell for latent-heat storage and photocatalytic effectiveness

    International Nuclear Information System (INIS)

    Chai, Luxiao; Wang, Xiaodong; Wu, Dezhen

    2015-01-01

    Highlights: • We designed and synthesized a sort of bifunctional PCMs-based microcapsules. • These microcapsules have an n-eicosane core and a crystalline TiO 2 shell. • Such a crystalline TiO 2 shell exhibited a good photocatalytic activity. • The microcapsules showed good performance in energy storage and sterilization. - Abstract: A sort of novel bifunctional microencapsulated phase change material (PCM) was designed by encapsulating n-eicosane into a crystalline titanium dioxide (TiO 2 ) shell and, then, was successfully synthesized through in-situ polycondensation in the sol–gel process using tetrabutyl titanate as a titania precursor. The resultant microcapsule samples were characterized by Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy to determine their chemical compositions and structures. Furthermore, the crystallinity of the TiO 2 shell was verified by powder X-ray diffraction patterns. It was confirmed that the fluorinions could induce the phase transition from the amorphous TiO 2 to the brookite-form crystals during the sol–gel process, thus resulting in a crystalline TiO 2 shell for the microencapsulated n-eicosane. The scanning and transmission electron microscopy investigations indicated that all of the resultant microcapsules presented a perfect spherical shape with a uniform particle size of 1.5–2 μm, and they also exhibited a well-defined core–shell structure as well as a smooth and compact shell. The crystalline TiO 2 shell made the resultant microcapsules a photocatalytic activity, and therefore, these microcapsules demonstrated a good photocatalytic effect for the chemical degradation and an antimicrobial function for some of the Gram-negative bacteria. Most of all, all of the microencapsulated n-eicosane samples indicated good phase-change performance and high thermal reliability for latent-heat storage and release, and moreover, they achieved a high

  8. New method for studying the efficiency of chelating agents of the polyamine acid series for internal decontamination

    International Nuclear Information System (INIS)

    Lafuma, J.; Nenot, J.C.; Morin, M.

    1968-01-01

    We followed the biological fate of a complex formed on one side with either a rare earth (cerium-144) or a transuranium element (plutonium-239), and on the other side with a chelating agent of the polyamino acid series (EDTA, BAETA, DTPA, TTHA). This method allowed to study: 1 - the in vivo stability of the various complexes and to compare them; 2 - the stability of the complexes as a function of the isotope - chelating agent weight relationships; 3 - the metabolism of the chelating agents resulting in stable complexes, i. e. DTPA and TTHA mainly. This simple method brought out the higher efficiency, of DTPA in chelating rare earths and plutonium and for therapeutic purposes. (authors) [fr

  9. Ascorbate status modulates reticuloendothelial iron stores and response to deferasirox iron chelation in ascorbate-deficient rats

    DEFF Research Database (Denmark)

    Brewer, Casey; Otto-Duessel, Maya; Lykkesfeldt, Jens

    2012-01-01

    that vitamin C supplementation would improve the availability of transfusional iron to DFX treatment by promoting iron's redox cycling, increasing its soluble ferrous form and promoting its release from reticuloendothelial cells. Osteogenic dystrophy rats (n = 54) were given iron dextran injections for 10......Iron chelation is essential to patients on chronic blood transfusions to prevent toxicity from iron overload and remove excess iron. Deferasirox (DFX) is the most commonly used iron chelator in the United States; however, some patients are relatively refractory to DFX therapy. We postulated...... weeks. Cardiac and liver iron levels were measured after iron loading (n = 18), 12 weeks of sham chelation (n = 18), and 12 weeks of DFX chelation (n = 18) at 75 mg/kg/day. Ascorbate supplementation of 150 ppm, 900 ppm, and 2250 ppm was used in the chow to mimic a broad range of ascorbate status; plasma...

  10. Spectral and magnetic investigations of lanthanide chelate compounds with Schiff bases coordinated via nitrogen and oxygen atoms

    International Nuclear Information System (INIS)

    Gupta, S.P.; Sharma, K.G.

    1982-01-01

    Nine-coordination lanthanide chelate of the type [LnL 3 ] and [LnL' 3 ] where Ln--Pr 3 , Nd 3 , Sm 3 , Ho 3 , Er 3 ; LH=O-(N-α-furfurylidenemino) etbanesulfonic acid (HFES)-LL'H=O-(N-α- furfurylidenemino) benzenesulfonic acid (HFBS) are synthesized by means of ligand reaction with Ln(NO 3 ) 3 . The chelates prepared are singled out in a solid state and are characterized using the element analysis, magnetic and spectral data, as well as the method of electric conductivity. At room temperature magnetic momenta of the chelates are characteristic of trivalent lanthanide ions. Electron spectra consist of absorption bands of f-f transitions and they are interpreted in the framework of LSI model. For the chelates prepared a polymeric structure with coordination number 9 is suggested in which lanthanide ions are bonded through oxygen and nitrogen atoms of schiff base [ru

  11. Nanogel-DFO conjugates as a model to investigate pharmacokinetics, biodistribution, and iron chelation in vivo.

    Science.gov (United States)

    Wang, Yan; Liu, Zhi; Lin, Tien-Min; Chanana, Shaurya; Xiong, May P

    2018-03-01

    Deferoxamine (DFO) to treat iron overload (IO) has been limited by toxicity issues and short circulation times and it would be desirable to prolong circulation to improve non-transferrin bound iron (NTBI) chelation. In addition, DFO is currently unable to efficiently target the large pool of iron in the liver and spleen. Nanogel-Deferoxamine conjugates (NG-DFO) can prove useful as a model to investigate the pharmacokinetic (PK) properties and biodistribution (BD) behavior of iron-chelating macromolecules and their overall effect on serum ferritin levels. NG-DFO reduced the cytotoxicity of DFO and significantly reduced cellular ferritin levels in IO macrophages in vitro. PK/BD studies in normal rats revealed that NG-DFO displayed prolonged circulation and preferential accumulation into the liver and spleen. IO mice treated with NG1-DFO presented significantly lower levels of serum ferritin compared to DFO. Total renal and fecal elimination data point to the need to balance prolonged circulation with controlled degradation to accelerate clearance of iron-chelating macromolecules. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Chelation of Thallium (III) in Rats Using Combined Deferasirox and Deferiprone Therapy

    Science.gov (United States)

    Salehi, Samie; Saljooghi, Amir Sh.; Badiee, Somayeh; Moqadam, Mojtaba Mashmool

    2017-01-01

    Thallium and its compounds are a class of highly toxic chemicals that cause wide-ranging symptoms such as gastrointestinal disturbances; polyneuritis; encephalopathy; tachycardia; skin eruptions; hepatic, renal, cardiac, and neurological toxicities; and have mutagenic and genotoxic effects. The present research aimed to evaluate the efficacy of the chelating agents deferasirox (DFX) and deferiprone (L1) in reducing serum and tissue thallium levels after the administration of thallium (III), according to two different dosing regimens, to several groups of Wistar rats for 60 days. It was hypothesized that the two chelators might be more efficient as a combined therapy than as monotherapies in removing thallium (III) from the rats’ organs. The chelators were administered orally as either single or combined therapies for a period of 14 days. Serum and tissue thallium (III) and iron concentrations were determined by flame atomic absorption spectroscopy. Serum and tissue thallium (III) levels were significantly reduced by combined therapy with DFX and L1. Additionally, iron concentrations returned to normal levels and symptoms of toxicity decreased. PMID:29071014

  13. Is aceruloplasminemia treatable? Combining iron chelation and fresh-frozen plasma treatment.

    Science.gov (United States)

    Poli, L; Alberici, A; Buzzi, P; Marchina, E; Lanari, A; Arosio, C; Ciccone, A; Semeraro, F; Gasparotti, R; Padovani, A; Borroni, Barbara

    2017-02-01

    We report the case of a patient with hereditary ceruloplasmin deficiency due to a novel gene mutation in ceruloplasmin gene (CP), treated with fresh frozen plasma (FFP) and iron chelation therapy. A 59-year-old man with a past history of diabetes was admitted to our department due to progressive gait difficulties and cognitive impairment. Neurological examination revealed a moderate cognitive decline, with mild extrapyramidal symptoms, ataxia, and myoclonus. Brain T2-weighted MR imaging showed bilateral basal ganglia hypointensity with diffuse iron deposition. Increased serum ferritin, low serum copper concentration, undetectable ceruloplasmin, and normal urinary copper excretion were found. The genetic analysis of the CP (OMIM #604290) reported compound heterozygosity for two mutations, namely c.848G > A and c.2689_2690delCT. Treatment with FFP (500 mL i.v./once a week) and administration of iron chelator (Deferoxamine 1000 mg i.v/die for 5 days, followed by Deferiprone 500 mg/die per os) were undertaken. At the 6-month follow-up, clinical improvement of gait instability, trunk ataxia, and myoclonus was observed; brain MRI scan showed no further progression of basal ganglia T2 hypointensity. This case report suggests that the early initiation of combined treatment with FFP and iron chelation may be useful to reduce the accumulation of iron in the central nervous system and to improve the neurological symptoms.

  14. A Powerful Mitochondria-Targeted Iron Chelator Affords High Photoprotection against Solar Ultraviolet A Radiation.

    Science.gov (United States)

    Reelfs, Olivier; Abbate, Vincenzo; Hider, Robert C; Pourzand, Charareh

    2016-08-01

    Mitochondria are the principal destination for labile iron, making these organelles particularly susceptible to oxidative damage on exposure to ultraviolet A (UVA, 320-400 nm), the oxidizing component of sunlight. The labile iron-mediated oxidative damage caused by UVA to mitochondria leads to necrotic cell death via adenosine triphosphate depletion. Therefore, targeted removal of mitochondrial labile iron via highly specific tools from these organelles may be an effective approach to protect the skin cells against the harmful effects of UVA. In this work, we designed a mitochondria-targeted hexadentate (tricatechol-based) iron chelator linked to mitochondria-homing SS-like peptides. The photoprotective potential of this compound against UVA-induced oxidative damage and cell death was evaluated in cultured primary skin fibroblasts. Our results show that this compound provides unprecedented protection against UVA-induced mitochondrial damage, adenosine triphosphate depletion, and the ensuing necrotic cell death in skin fibroblasts, and this effect is fully related to its potent iron-chelating property in the organelle. This mitochondria-targeted iron chelator has therefore promising potential for skin photoprotection against the deleterious effects of the UVA component of sunlight. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  15. Gd (III) chelates adsorbed on TiO2 nanoparticles - promising MRI contrast agent

    International Nuclear Information System (INIS)

    Rehor, Ivan; Lukes, Ivan; Peters, Joop A.; Jirak, Daniel

    2009-01-01

    Full text: The project deals with a new contrast agent (CA) for magnetic resonance imaging (MRI). The CA consists of two main parts - diamagnetic core (TiO 2 nanoparticle) and Gd (III) chelates grafted on its surface. The presence of the nanoparticle core is responsible for significant increase of r1 millimolar relaxivity (which corresponds to the efficiency of the CA) due to the slowing down the rotation of the complex in solution. It also affects the biodistribution characteristics of the CA - the ability to penetrate through cell membranes is well known for nanoparticles, making them useful for cell labeling. The structure of the chelate is derived from DOTA ligand, whose Gd (III) complexes are commercially used as MRI CA in human medicine. The connection of the complex to the surface is realized via penylphosphonate, which is attached to the pendant arm of the ligand. Strong interaction of the phosphonate with the TiO 2 surface results in the full surface coverage. The complexation and MRI properties of Gd chelate were studied and exhibit analogy to the complexes of DOTA, The millimolar relaxivity (r1) of the Gd (III) complex significantly increases upon adsorption on the TiO 2 nanoparticles. PVA was added to the colloidal solutions of CA to stabilize them under biological conditions and such stabilized CA was utilized for MRI visualization of rat pancreatic islets (P1). The labeled islets were detected on MR images as hyperintense area and therefore our CA seems to be promising material for cellular MRI

  16. 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.

  17. 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.

  18. 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.

  19. Luminescent solutions and powders of new samarium complexes with N,N',O,O'-chelating ligands

    Science.gov (United States)

    Kharcheva, Anastasia V.; Nikolskiy, Kirill S.; Borisova, Nataliya E.; Ivanov, Alexey V.; Reshetova, Marina D.; Yuzhakov, Viktor I.; Patsaeva, Svetlana V.

    2016-04-01

    Imaging techniques in biology and medicine are crucial tools to obtain information on structural and functional properties of living cells and organisms. To fulfill the requirements associated with application of these techniques it appears necessary to design markers with specific characteristics. Luminescent complexes of trivalent lanthanide ions with chelating ligands are of increasing importance in biomedical applications because of their millisecond luminescence lifetime, narrow emission band, high signal-to-noise ratio and minimal photodamage to biological samples. In order to extend the available emission wavelength range the luminescent samarium chelates are highly desirable. In this study the ligands with diamides of 2,2'-bipyridin-6,6'-dicarboxylic acid were used to improve photophysical characteristics of samarium complexes. We report the luminescence characteristics of samarium complexes with novel ligands. All complexes exhibited the characteristic emission of Sm (III) ion with the lines at 565, 597, 605, 645 and 654 nm, the intensity strongly depended on the ligand. Absorption and luminescence excitation spectra of Sm (III) complexes showed main peaks in the UV range demonstrating lanthanide coordination to the ligand. The absolute lumenescence quantum yield was measured for solutions in acetonitrile with excitation at 350 nm. The largest luminescence quantum yield was found for the samarium complex Bipy 6MePy Sm (3%) being much higher that for samarium complexes reported in the literature earlier. These results prove as well that samarium chelates are potential markers for multiparametric imaging techniques.

  20. Mutational reconstructed ferric chelate reductase confers enhanced tolerance in rice to iron deficiency in calcareous soil.

    Science.gov (United States)

    Ishimaru, Yasuhiro; Kim, Suyeon; Tsukamoto, Takashi; Oki, Hiroyuki; Kobayashi, Takanori; Watanabe, Satoshi; Matsuhashi, Shinpei; Takahashi, Michiko; Nakanishi, Hiromi; Mori, Satoshi; Nishizawa, Naoko K

    2007-05-01

    Iron (Fe) deficiency is a worldwide agricultural problem on calcareous soils with low-Fe availability due to high soil pH. Rice plants use a well documented phytosiderophore-based system (Strategy II) to take up Fe from the soil and also possess a direct Fe2+ transport system. Rice plants are extremely susceptible to low-Fe supply, however, because of low phytosiderophore secretion and low Fe3+ reduction activity. A yeast Fe3+ chelate-reductase gene refre1/372, selected for better performance at high pH, was fused to the promoter of the Fe-regulated transporter, OsIRT1, and introduced into rice plants. The transgene was expressed in response to a low-Fe nutritional status in roots of transformants. Transgenic rice plants expressing the refre1/372 gene showed higher Fe3+ chelate-reductase activity and a higher Fe-uptake rate than vector controls under Fe-deficient conditions. Consequently, transgenic rice plants exhibited an enhanced tolerance to low-Fe availability and 7.9x the grain yield of nontransformed plants in calcareous soils. This report shows that enhancing the Fe3+ chelate-reductase activity of rice plants that normally have low endogenous levels confers resistance to Fe deficiency.