Metal-chelate Complex Research Articles

Structural and Biophysical Characterization of EppA

Ethylenediaminetetraacetate (EDTA) is an anthropogenic aminopolycarboxylate chelator whose widespread use, combined with its chemical stability, has led to its persistence in the environment as metal-chelate complexes. Being a ubiquitous environmental pollutant, finding a means by which we can clean up EDTA pollution in the environment is imperative. One way to remove EDTA is through bioremediation in which a unique microbial process is harnessed, such as the epp-emo pathway from Chelativorans sp. BNC1. Although the enzymatic pathway has been characterized, the biophysical mechanism of the associated ABC-type transporter is incomplete thus far. To these ends, we characterized the relationship between the structure and function of EppA, an EDTA-binding periplasmic protein. To obtain the molecular structure of EppA, single-crystal X-ray diffraction was used. Molecular docking was used to dock EDTA and chemically related chelators to the structure, showing that they bind with EppA's putative ligand-binding cleft. To confirm their binding experimentally, isothermal titration calorimetry was performed. EppA's high affinity for chemically similar chelators suggests that other proteins further down the catabolic pathway may be useful for degrading a wider range of chelators than previously thought or can otherwise be engineered to do so. This makes the epp-emo EDTA-degradation pathway of Chelativorans sp. BNC1 a powerful tool for combating pollution.

Chelator-assisted washing for the extraction of lead, copper, and zinc from contaminated soils: A remediation approach

Chelators have proven to be effective extractants in soil washing and represent a suitable remediation technology for potentially toxic elements (PTEs) from contaminated sites. In this paper, the extraction of lead (Pb), copper (Cu), and zinc (Zn) from contaminated real and reference soils using both biodegradable (EDDS and HIDS) and persistent (EDTA and DTPA) chelators was investigated. Different metal–chelator complex formation constants, pH, extraction temperature, and mechanochemical energy were tested. The PTEs were extracted at a relatively higher rate under acidic to neutral conditions (pH 5 and 7), with the greatest extraction being observed at pH 5. The metal extraction efficiencies of the chelators for the real sample at pH 5 were as follows: Pb – EDTA > DTPA > EDDS > HIDS; Cu – DTPA > EDTA > EDDS > HIDS; and Zn – DTPA > EDTA > HIDS > EDDS. The data suggested that EDDS was more effective than HIDS for Cu and Zn extraction in neutral to slightly alkaline solutions, as well as at raised temperature. Furthermore, EDTA washing using mechanochemical agitation was found to enhance the removal efficiency of Cu and Zn. Sequential chemical extraction showed that the apparent metal mobilities were reduced by soil washing. EDTA and DTPA appeared to offer greater potential than the biodegradable chelators in extracting metals from the relatively mobile carbonate- and Fe–Mn oxide-bound fractions. The residual fraction of Pb displayed considerable stability (≥70%), and was not entirely amenable under washing treatments, and hence could be considered non-bioavailable and non-toxic.

Chelated Chromium Electrolyte Enabling High-Voltage Aqueous Flow Batteries

Summary Widespread adoption of renewable energy is limited by the lack of low-cost long-duration energy storage. Redox flow batteries are an attractive option to provide this type of storage because their power and energy components can be scaled independently; however, systems commercialized to date have failed to realize this low-cost potential, primarily because of the cost and performance of the battery chemistry. Here, we resolve these challenges with a negative electrolyte comprised of earth-abundant chromium and an inexpensive chelating agent which operates at a more reducing potential than zinc while inhibiting hydrogen production. Utilizing this electrolyte, we report two of the highest voltage aqueous flow batteries, which have stably operated at room temperature and near neutral pH with high efficiency and high power density. These results demonstrate the ability of chelated metal complexes to prevent water coordination and establish a general method for inhibiting water splitting reactions at highly negative potentials.

Improving the Tribological Properties of Polyethylene Products by Modification with Metal Chelate Complexes

The results of studying the improvement of tribological properties of polyethylene products by modification with Nd and Al chelate complexes containing bulky tert-butyl groups in the ligand surrounding are given. The effect of additives on the coefficient of friction and wear of friction parts under static load is studied. The influence of coordination compounds on thermomechanical characteristics of polymers is studied. It is shown the treatment of polyethylene with Nd and Al complexes gives rise to a 1.2- to 1.5-fold decrease in the coefficient of friction and a 1.5- to 2-fold increase in the wear resistance.

Migration and decomplexation of metal-chelate complexes causing metal accumulation phenomenon after chelate-enhanced electrokinetic remediation.

This study investigates the migration and decomplexation effects of metal-ethylenediaminetetraacetic acid (EDTA) complexes during an electrokinetic (EK) remediation process and the resulting metal accumulation phenomena. Six EK tests with control of the electrolyte pH and using ion-exchange membranes were performed to treat Pb-EDTA and Cd-EDTA co-contaminated red soil. The obtained results showed that a portion of free metal cations could be decomplexed from the metal-EDTA complexes due to the low pH and electrochemical degradation at the anode. These cations went back into the soil by electromigration and accumulated in separate locations according to their hydrolysis ability and the distribution of soil pH in different sections. Totals of 61% Cd and 83% Pb were removed from the soil after a 7-day treatment under the condition of controlling the electrolyte pH at 10. The removal efficiencies of metals under the anion-exchange membrane-assisted treatment were higher than those of the cation-exchange membrane-assisted treatment. Based on the mechanisms of metal accumulation phenomena, the migration of decomplexed free metal cations back to the soil is limited by using an anion-exchange membrane or pre-precipitation with alkaline conditions was confirmed to effectively reduce the effect of metal accumulation.

The effect of metal-chelate complex in Cu2SnS3 thin film solar cells and their characteristics, photovoltaic performance, and defect analysis

Hybrid inks with a chelating agent were prepared and coated by a spin-coating method to form Cu2SnS3 (CTS) thin films. After the coating, a subsequent sulfurizing process via rapid thermal annealing was performed. During the sulfurization, the Cu and Sn precursors in the hybrid inks exist in complex forms with chelates and these complexes help to form the CTS thin films by controlling the reaction rate of the metal precursors. Additionally, even though the complexes with chelates were formed, the oxidation numbers of the metal precursors were affected by the ionization tendency of each metal in the hybrid inks to form the semiconducting CTS thin films. After obtaining the optimum sulfurizing condition by controlling the reaction pressure and temperature, the CTS thin films were characterized and CTS solar cells were fabricated under these conditions. The best conversion efficiency of the fabricated cells was 2.953% and the temperature-dependent photovoltaic performances were also examined to investigate the carrier transport mechanisms of the devices. According to admittance spectroscopy, the dominant defect energy level was determined as 0.09 eV above the valence band minimum, which accords with the copper vacancy (VCu) level. In addition, capacitance–voltage measurements and drive-level capacitance profiling were applied to demonstrate the carrier densities and defect behaviors.

Ni(II)-decorated porous titania microspheres as a stationary phase for column chromatography applications: Highly selective purification of hemoglobin from human blood

Titania (TiO2)-based monodisperse-porous stationary phase/sorbent was synthesized by decoration of Ni(II) ions onto TiO2 microspheres 4.2 µm in size, obtained by a staged-shape template hydrolysis and condensation protocol. Ni(II) ions were attached onto iminodiacetic acid-3-glycidoxypropyltrimethoxysilane (IDA-GPTMS) bound-titania microspheres by metal-chelate complex formation. The appropriate mean size, sufficiently high surface area and high porosity providing an appropriate column permeability make Ni(II)-decorated TiO2 microspheres a good sorbent/stationary phase for batch/continuous-column chromatography applications. Ni(II)-decorated TiO2 microspheres were investigated as a sorbent for purification of a typical histidine-rich protein, hemoglobin (Hb) via immobilized metal affinity chromatography (IMAC) in batch fashion, by including bovine serum albumin (BSA) as reference. The saturation capacities of batch adsorption runs performed with bovine Hb and BSA were determined as 137 ± 9 and 45 ± 3 mg/g, respectively. Human Hb with the purity of > 95% was recovered from whole blood by IMAC conducted in batch-fashion. Ni(II)-decorated microspheres were also evaluated as a stationary phase in a microfluidic-IMAC system, in which, human Hb was recovered from whole blood with a purity of 85%. The microfluidic-IMAC system constructed here, based on monodisperse-porous TiO2 microspheres, is a promising tool for genomics/proteomics applications involving isolation of valuable biomolecules from low-volume samples.

Ammonia ligand and transition metal salt complexation on naturally dyed textile surface: A reflectance spectroscopic investigation to understand coloration and fastness properties

Ammonia is a stronger ligand and can replace water molecules in a chelate metal complex as per spectrochemical series. This property of ammonia was utilized in this work for the coloration of wool in order to obtain some unusual effects. Different concentrations of ammonia solution was applied on Butea monosperma flower extract dyed wool previously premordanted with ferrous sulfate salt to evaluate the effect on colorimetric properties. A range of newer shades were produced on wool substrates which were characterized in terms of K/S, CIELa*b* values and fastness properties. The observed effects exhibited on wool and acceptable fastness properties of produced shades points out a promising approach for developing environmentally sustainable colorful textile materials and clothing. The chemical modification of wool before and after application of ammonia was also evaluated using Fourier transform infrared spectrometer analysis. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019

Janus multi-responsive superparamagnetic nanoparticles functionalized with two on-demand and independently cleavable ligands for Actinide separation

HypothesisNanoparticles functionalized with ligands which can on-demand and remotely be detached have recently attracted interest as stimuli-responsive materials. Research is now focused on multi-responsive systems, with applications in environmental science and biomedicine. The possibility to covalently couple two different ligands on a single nanoparticles, and to release them independently is investigated. This concept of nanoparticles functionalized with dual on-demand cleavable ligands is exploited in ground water decontamination and radionuclides separation. Efficient separation of contaminants in a single step is expected, simplifying partitioning process and decreasing generation of secondary waste by nuclear industry. ExperimentsSub−10 nm Janus superparamagnetic nanoparticles are functionalized by click-chemistry (thiol and Diels-Alder) with two different Actinide-specific chelators. The reversible covalent bonds allow to detach chelators independently by either pH- or thermo-stimulation. The nanoparticles decorated with diethylenetriamine-pentaacetic acid (DTPA) and [(2-furan-2-yl-2-hydroxy-ethylcarbamoyl)-methoxy]-acetic acid (FHECMAA) are incubated with UO22+ and La3+ (as substitute for Pu3+) at pH = 3 and 7 before chelator-metal complexes are released. Metal contents are measured to determine separation efficiency. FindingsChelators can be detached from Janus nanoparticles with perfect selectivity. The nanoparticles are highly efficient for extraction of metals in acidic medium and show good ability for separation of U and La at neutral pH.

Metallonanobelt: A Kinetically Stable Shape-Persistent Molecular Belt Prepared by Reversible Self-Assembly Processes.

A triptycene-based shape-persistent belt-shaped macrocycle, metallonanobelt, was synthesized by the self-assembly of 2,3,6,7-tetraaminotriptycene L and square planar Pd2+. The pentamer was selectively formed by the complexation of L with Pd2+ in the presence of the pillar[6]arene derivative P6 having triethylene glycol pendant as a template, whereas a mixture of a trimer, tetramer, and pentamer was obtained in the absence of the template. The pentamer was successfully isolated based on the solubility difference between the metallonanobelt and the template. It was also revealed that the isolated pentamer was remarkably stable in solutions such as acetonitrile or methanol thanks to the relatively inert planar chelate metal complex, [Pd( o-phenylenediamine)2] unit. Thus, we can handle the metallonanobelt almost as a static organic nanobelt that is synthesized covalently.

Enhanced Specificity and Sensitivity for the Determination of Nickel(II) by Square-wave Adsorptive Cathodic Stripping Voltammetry at Disposable Graphene-modified Pencil Graphite Electrodes

Chemical sensors relying on graphene-based materials have been widely used for electrochemical determination of metal ions and have demonstrated excellent signal amplification. This study reports an electrochemically reduced graphene oxide (ERGO)/mercury film (HgF) nanocomposite-modified pencil graphite electrode (PGE) prepared through successive electrochemical reduction of graphene oxide (GO) sheets and an in situ plated HgF. The ERGO-PG-HgFE, in combination with dimethylglyoxime (DMG) and square-wave adsorptive cathodic stripping voltammetry (SW-AdCSV), was evaluated for the determination of Ni2+ in tap and natural river water samples. A single-step electrode pre-concentration approach was employed for the in situ Hg-film electroplating, metal-chelate complex formation, and non-electrolytic adsorption at –0.7 V. The current response due to nickel-dimethylglyoxime [Ni(II)-DMG2] complex reduction was studied as a function of experimental paratmeters including the accumulation potential, accumulation time, rotation speed, frequency and amplitude, and carefully optimized for the determination of Ni2+ at low concentration levels (μg L−1) in pH 9.4 of 0.1 M NH3–NH4Cl buffer. The reduction peak currents were linear with the Ni2+ concentration between 2 and 16 μg L−1. The limits of detection and quantitation were 0.120 ± 0.002 µg L−1 and 0.401 ± 0.007 µg L−1 respectively, for the determination of Ni2+ at an accumulation time of 120 s. The ERGO-PG-HgFE further demonstrated a highly selective stripping response toward Ni2+ determination compared to Co2+. The electrode was found to be sufficiently sensitive to determine metal ions in water samples at 0.1 µg L−1, well below the World Health Organization standards.

Interactions of food waste compost with metals and metal-chelant complexes during soil remediation

Abstract For removing potentially toxic elements (PTEs) from field-contaminated soils, cost-effective soil remediation has been a worldwide concern. As one of the widely employed techniques, chelant-enhanced phytoremediation can remove PTEs with marginal impact on the soil properties, yet the newly formed metal-chelant complexes cannot be completely captured and extracted by the plants. This arouses concerns about downstream migration and secondary contamination of the metal-chelant complexes and free chelant. Organic amendments, such as food waste compost (FWC), may stabilize metals and/or metal-chelant complexes, improve soil properties and plant growth, and reduce waste volume. Therefore, FWC may provide a solution for the migration of metal-chelant complexes and free chelant. Two chelants were selected in this study: EDTA (ethylene-diaminetetraacetic-acid) and its biodegradable isomer EDDS ([S,S]-ethylenediaminedisuccinic acid). The interactions between FWC and metals, metal-EDTA/metal-EDDS complexes in a field-contaminated soil (mainly by Cu, Zn, and Pb) were investigated. Batch adsorption isotherms indicated a strong adsorption capacity of FWC for uncomplexed Cu, Zn, and Pb ions. Significant adsorption of Pb-EDDS (∼100%), Zn-EDDS (>77%), and Cu-EDTA (36–76%) complexes on the FWC was found at apparent equilibrium. The adsorption capacity of Cu-EDDS (32–38%), Pb-EDTA (∼20%), and Zn-EDTA (∼0%) complexes was limited. However, the co-existence of FWC and EDDS increased the mobilization of Cu and Zn, while the co-existence of FWC and EDTA reduced the available amounts of Cu and Pb in solution. Metal speciation calculation showed that nearly all extracted Cu, Zn, and Pb were complexed with chelants in the solution, while notable amount of dissolved Fe (but not Al and Ca) was associated with dissolved organic matter. In this study, FWC can be useful for minimizing the unintended leaching of Cu- and Pb-EDTA complexes in EDTA-enhanced phytoremediation, yet it might be less suitable for the case of EDDS. A novel integration of recycled waste can enhance the effectiveness of sustainable remediation of contaminated soils.

Combined application of EDDS and EDTA for removal of potentially toxic elements under multiple soil washing schemes

Chelant-enhanced soil washing, such as EDTA (ethylenediaminetetraacetic acid) and biodegradable EDDS ([S,S]-ethylene-diamine-disuccinic acid), has been widely studied, however, EDTA is persistent under natural conditions while EDDS has a low efficiency for Pb extraction. Therefore, we investigated the efficacy of mixed chelants (EDDS and EDTA mixture at 1:1 M ratio) for the removal of Cu, Zn, and Pb from a field-contaminated soil using various washing schemes (multi-pulse, step-gradient chelant, and continuous washing schemes). Speciation modelling of the target metals, mineral elements, and EDDS/EDTA was performed, while the leachability and bioaccessibility of residual metals in the treated soils were also assessed. Our results suggested that the combined use of EDDS and EDTA reached equivalent extraction efficiency of the target metals as EDTA, i.e., 50% reduction in the dosage of EDTA was made possible. This was accomplished by selective extraction of Cu by EDDS and Pb by EDTA, which was supported by the results of speciation calculation. Multi-pulse washing scheme with intermittent water rinsing steps removed entrapped metal-chelant complexes and free chelants, therefore reducing the leachability and bioaccessibility of residual metals in the treated soils. Step-gradient chelant washing with the maximum dosage of chelants in the first washing step only achieved marginal improvement but undesirably promoted Pb bioaccessibility. Continuous washing for 24 h enhanced metal extraction but promoted mineral dissolution, together with a large amount of uncomplexed chelants and increase in Cu leachability. Thus the combined use of EDDS and EDTA in multi-pulse washing is recommended for further studies.

Complexation behavior of SrII and geochemically-related elements (MgII, CaII, BaII, and YIII) with biodegradable aminopolycarboxylate chelators (GLDA and HIDS)

The complexation of SrII and geochemically-related elements (MgII, CaII, BaII, and YIII) with biodegradable aminopolycarboxylate chelators (DL-2-(2-carboxymethyl)nitrilotriacetic acid (GLDA) and 3-hydroxy-2,2′-iminodisuccinic acid (HIDS)) was evaluated with the objective of using in the chemical-induced washing remediation of radioactive solid waste. The stability constants (log10KML) for metal-chelator (ML) complexes between M (MgII, CaII, SrII, BaII, or YIII) and L (GLDA or HIDS) in the aqueous matrix was derived from experimental potentiometric data (M:L=1:1; ionic strength, I=0.10mol·dm−3; T=25±0.1°C). The formation of ML2− species was dominant in the systems with MgII, CaII, SrII, or BaII, while M(OH)L2− or M(OH)2L3− was the major species with YIII. The stability of YIII-L complexes was higher than that of MgII, CaII, SrII, or BaII, while the order for complexation strength of GLDA and HIDS was not similar with divalent ions: M-GLDA (log10KMg-L<log10KCa-L>log10KSr-L>log10KBa-L), M-HIDS (log10KMg-L>log10KCa-L>log10KSr-L>log10KBa-L). The conditional stability constants for the ML systems was also derived in terms of pH (2 to 12), and compared with that of EDTA and EDDS. The data trend indicated that the overall stability of the complexes of MgII, CaII, SrII, BaII, or YIII with GLDA or HIDS was better than the biodegradable chelator EDDS, which was frequently recommended as the alternative to EDTA.

Corrole Chelated Metal Complexes for HER and Oer

We have recently introduced corrole metal complexes (metallocorroles) as catalysts for various energy-relevant reactions. This includes those that are of prime importance for the electrochemical splitting of water into its elements, the hydrogen and oxygen evolution reactions. Tuning of the redox potentials, M(I)/M(II) for HER and M(III)/M(IV) for OER (M= Fe, Co, or Mn), is achieved via variations of substituents on the corrole ligand. These hypothesis-driven changes allow for the highly desired shifting of electrocatalytic onset potentials. On top of the already published results listed below, new approaches and novel catalysts will be disclosed. REFERENCES “Cobalt Corrole Catalyst for Efficient Hydrogen Evolution Reaction from H2O under Ambient Conditions: Reactivity, Spectroscopy and DFT Calculations”, Inorg. Chem. 2013, 52, 3381-3387. "The Cobalt Corrole Catalyzed Hydrogen Evolution Reaction: Surprising Electronic Effects and Characterization of Key Reaction Intermediates" Chem. Commun. 2014, 50, 2725-2727. "Metallocorroles as photocatalysts for driving endergonic reactions, exemplified by bromide to bromine conversion", Angew. Chem. 2015, 54, 12370 –12373. "Metallocorroles as Non-Precious Metal Catalysts for Oxygen Reduction", Angew. Chem. 2015 , 54, 14080 –14084. “Metallocorroles as Non-Precious Metal Electrocatalysts for Highly Efficient Oxygen Reduction in Alkaline Media" ChemCatChem 2016, 8, 2832-2837. “Metallocorroles as Electrocatalysts for the Oxygen Reduction Reaction (ORR)", Israel J. Chem. 2016, 56, 756– 762. “Dioxygen bound Cobalt Corroles”, Chem. Commun. 2017, in press.

Highly selective enrichment of phosphopeptides by titanium (IV) attached monodisperse-porous poly(vinylphosphonic acid-co-ethylene dimethacrylate) microspheres

A seeded polymerization protocol was developed for the synthesis of monodisperse-porous poly(vinylphosphonic acid-co-ethylene dimethacrylate), [poly(VPA-co-EDMA)] microspheres with superior porous properties. The protocol allowed the direct synthesis of phosphonic acid functionalized porous microspheres with the mean size of ∼4μm and the specific surface area of 420m2g−1 without applying any complicated post-derivatization protocol for the attachment of phosphonic acid group. The phosphonic acid content of poly(VPA-co-EDMA) microspheres was determined as 1.5mmol H2PO3g−1 microspheres. Ti(IV) ions were attached onto the microspheres via metal-chelate complex formation by phosphonate-groups and Ti(IV) carrying monodisperse-porous poly(vinylphosphonic acid-co-ethylene dimethacrylate), [Ti(IV)@poly(VPA-co-EDMA)] microspheres were obtained as a new sorbent for phosphopeptide enrichment via immobilized metal affinity chromatography. The phosphopeptides in the enriched samples were identified by matrix-assited laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Four different phosphopeptides were detected with extremely high intensity by the treatment of β-casein digest prepared with the concentration of 10 fmol/mL with Ti(IV)@poly(VPA-co-EDMA) microspheres. Highly selective enrichment of phosphopeptides was also successfully carried out even at trace amounts in a complex mixture of digested proteins (molar ratio of β-casein to BSA, 1:1000) and eight different phosphorylated peptides from BSA digest were successfully identified. Moreover, four highly intense signals of the phosphopeptides in human serum were observed with high S/N ratio and clear background after enrichment by using Ti(IV)@poly(VPA-co-EDMA) microspheres.

Molecular trail for the anticancer behavior of a novel copper carbohydrazone complex in BRCA1 mutated breast cancer.

Novel chelated metal complexes were synthesized from carbohydrazones to thiocarbohydrazones using metal-based drug designing platforms and their combination effect with Pb, a naphthaquinone were analyzed for anticancer activity in breast cancer cell lines. A panel of BRCA1 wild-type and mutated breast cancer cells: MCF-7 (BRCA1+ /ER+ ), MDA-MB-231 (BRCA1+ /ERα- ), HCC-1937 (BRCA1- /ERα- ), HCC1937/wt BRCA1, MX1 (BRCA1- /ERα- ), and MDA-MB-436 (BRCA1- /ERα- ) were screened for anti-cancer activity. Cu2 (HL)(HSO4 ) · H2 O]SO4 · 6 H2 O (CS2) is the most potent anticancer agent among the copper carbohydrazone and thiocarbohydrazone complexes analyzed in this study. It can be suggested that the presence of sulphate, as pharmacologically active centre, can induce cytotoxicity more effectively when compared to chlorine, bromine, perchlorate, and methanol. This is the first report demonstrating that CS2 can bind to DNA by hindering BamH1 activity and could induce DNA double strand breaks as evidenced by γ-H2AX expression. In addition to this, CS2 could also act as a Topo II inhibitor at a much lower concentration than etoposide and induce apoptosis, making it a potent anticancer agent. In combination with Pb, a potent ROS inducer, CS2 could induce synergistic anti-cancer activity in HR/ BRCA1 defective breast cancer cells. This is the first study reporting the mechanism involved in the induction of apoptosis for a metal chelated copper carbohydrazone complex and its combination effects with Pb in HR defective, BRCA1 mutated breast cancer cells.

The mechanism of d-metal ion sorption from aqueous media and chelating sites structures of modified heterocyclic biopolymers

Sorption of d-metal ions (Cu2+, Fe2+, and Ni2+) from aqueous media using modified heterocyclic biopolymers takes place with the participation of sorption sites, with the following acidic groups: α-hydroxycarboxylic (monobasic, bidentate), hydroxamic (monobasic, bidentate), and aldehyde bisulphite (dibasic) in the form of chelate metal complexes, whose structures were determined through the use of computational quantum chemistry on some modeled compounds. Ion exchange mechanism of the components of hetero-phase system in electroneutral, molecular form reflects the implementation of the general laws of thermodynamics: Gibbs’ phase rule, law of mass action, law of equivalent proportions, and law of conservation of charge at electroneutrality of phases. Sorbents functional groups act as sorption sites whose filling goes in accordance with their amount, denticity, basicity and ability of metal cations to complex formation and solvation. The amount and the nature of acid sorption sites of sorbents permits the comparison of their initial and maximum sorption abilities.

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

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.

Effect of EDTA, EDDS, NTA and citric acid on electrokinetic remediation of As, Cd, Cr, Cu, Ni, Pb and Zn contaminated dredged marine sediment.

In recent years, electrokinetic (EK) remediation method has been widely considered to remove metal pollutants from contaminated dredged sediments. Chelating agents are used as electrolyte solutions to increase metal mobility. This study aims to investigate heavy metal (HM) (As, Cd, Cr, Cu, Ni, Pb and Zn) mobility by assessing the effect of different chelating agents (ethylenediaminetetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), nitrilotriacetic acid (NTA) or citric acid (CA)) in enhancing EK remediation efficiency. The results show that, for the same concentration (0.1molL(-1)), EDTA is more suitable to enhance removal of Ni (52.8%), Pb (60.1%) and Zn (34.9%). EDDS provides effectiveness to increase Cu removal efficiency (52%), while EDTA and EDDS have a similar enhancement removal effect on As EK remediation (30.5∼31.3%). CA is more suitable to enhance Cd removal (40.2%). Similar Cr removal efficiency was provided by EK remediation tests (35.6∼43.5%). In the migration of metal-chelate complexes being directed towards the anode, metals are accumulated in the middle sections of the sediment matrix for the tests performed with EDTA, NTA and CA. But, low accumulation of metal contamination in the sediment was observed in the test using EDDS.