Strong Chelating Ability Research Articles

Structural characterization, antioxidant and hepatoprotective activities of polysaccharides from Sophorae tonkinensis Radix

In current study we present two polysaccharides, STRP1 and STRP2, purified from Sophorae tonkinensis Radix via column chromatography. Structural analyses indicated that STRP1 and STRP2 were consisted of mannose, rhamnose, glucuronic acid, glucose, galactose and arabinose in a similar molar ratio with main backbones of (1 → 3)-linked-α-d-Gal and (1 → 4)-linked-α-d-Glc, while average molecular weights were 1.30 × 104 and 1.98 × 105 Da, respectively. We observed a strong chelating ability on ferrous ions; substantial radical scavenging activities on DPPH, hydroxyl and superoxide anion radicals in vitro; and significant attenuation on acetaminophen-induced hepatic oxidative damage in mice for STRP1 and STRP2. The promising data on these polysaccharides showcase the need to further develop novel natural antioxidant and liver-protecting drugs.

Effect of Chelating Agent and Ammonium Dodecyl Sulfate on the Interfacial Behavior of Copper CMP for GLSI

Multi-layered copper wiring chemical mechanical planarization (CMP) of Giant Large Scale Integrated circuit (GLSI) is one of the key processes for the improvement of microelectronic technique. During copper interconnection CMP, high removal rate (RR) and lower surface roughness for copper film are required. Slurry is one of the key factors to achieve highly effective planarization for copper film, and is also one of the research hotspots. In this work CMP and electrochemical behavior of copper with the synergistic effect of chelating agent and Ammonium Dodecyl Sulfate (ADS) using a new type alkalescent slurry was investigated. The slurry was composed of colloidal silica, FAOII chelating agent, surfactant (ADS) and hydrogen peroxide. The Potentiodynamic polarization plots revealed that FAOII chelating agent had strong chelating ability to improve copper removal rate, which was verified by polishing experiments. When FAOII concentration increasing from 0 to 5wt%, copper RR dramatically increased from 377Å/min to 5523Å/min. [CuR(NH2)2]2 + as one of the key generated products relating to RR improvement was verified by XPS. Meanwhile, with the addition of ADS, the static etch rate decreased from 1080Å/min to 442Å/min, and the surface roughness decreased from 4.81nm to 2.69nm, which indicated that ADS acted as a surfactant and an inhibitor simultaneously. From the result it can be seen that high and controllable removal rate and low surface roughness can be achieved by adjusting the concentration of FAOII chelating agent and anionic surfactant ADS. Slurry is stabilized till 48 hours. Such simple and component adjustable alkalescent slurry has certain guiding significance to practical production.

A Green Route to Copper Loaded Silica Nanoparticles Using Hyperbranched Poly(Ethylene Imine) as a Biomimetic Template: Application in Heterogeneous Catalysis

Copper containing silica nanostructures are easily produced through a low cost versatile approach by means of hyperbranched polyethyleneimine (PEI), a water soluble dendritic polymer. This dendritic molecule enables the formation of hybrid organic/inorganic silica nanoparticles in buffered aqueous media, at room temperature and neutral pH, through a biomimetic silicification process. Furthermore, the derived hybrid organic/inorganic materials dispersed in water can be easily loaded with various copper amounts, due to the presence of PEI, which, despite having been integrated in the silica network, retains its strong copper chelating ability. Following calcination, the obtained copper loaded nanopowders are characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), N2 adsorption, Temperature programmed reduction (TPR) and UV-Vis diffuse reflectance (UV-Vis-DR) techniques and evaluated for automotive exhaust purification under simulated conditions at the stoichiometric point. Effective control over final materials’ pore structural and morphological characteristics is provided by employing different buffer solutions, i.e., tris(hydroxymethyl)aminomethane (Tris) or phosphate buffer. It was found that the enhancement of the nanopowders textural features, obtained in the presence of Tris buffer, had a great impact on the material’s catalytic behavior, improving significantly its activity towards pollutants oxidation.

Removal of low concentration CH3SH with regenerable Cu-doped mesoporous silica

Mercaptans are highly volatile compounds responsible for disagreeable odors and very low olfactory threshold, especially for CH3SH (0.4 ppvb). To the best knowledge of us, approach for controlling low-concentrated odors (i.e. 1–10 ppm) is scarcely reported. In this research, Cu-doped mesoporous silica was synthesized for removal of low-concentrated CH3SH. The as-prepared samples show considerably thermal and mechanical stability and could be thermal-regenerated. Copper loading ratio and humidity have significant impacts on eliminating odors. According to XRD, TEM, BET, NMR and EPR, we deduce that surface groups on CuO nanoparticles and the SiOCu group are highly possibly transformed into a hydrated complex which is much more effective in capturing CH3SH with its empty Cu-3d orbit. Although CH3SH has to compete with water for absorption sites, it is always the “winner” owing to the strong chelating ability between SH group and Cu (Ⅱ).

Palladium Nanoparticles Supported by Carboxylate-Functionalized Porous Organic Polymers for Additive-Free Hydrogen Generation from Formic Acid

Facile hydrogen generation from formic acid (FA) is a promising way of hydrogen storage and release in the fuel-cell-based hydrogen economy; the development of efficient heterogeneous catalyst systems for ultrapure H2 generation from FA in the absence of additives remains a major challenge. Herein, we present a prefunctionalized porous organic polymer (POP) containing 2,6-bis(1,2,3-triazol-4-yl)pyridyl (BTP) units and carboxylate groups. The terdentate BTP and hydrophilic carboxylate are homogeneously incorporated into the host framework of the POP. BTP units with strong chelating ability can effectively stabilize palladium nanoparticles for heterogeneous dehydrogenation of FA, whereas carboxylate not only increases polarity and dispersibility of the catalytic system in aqueous solutions but also functions as basic sites to facilitate the O–H bond dissociation. The catalytic system shows high catalytic activity, excellent stability and superior recyclability in H2 generation from aqueous FA without any ad...

Removal of heavy metal ions by magnetic chitosan nanoparticles prepared continuously via high-gravity reactive precipitation method

This study aimed to provide a continuous method for the preparation of magnetic Fe3O4/Chitosan nanoparticles (Fe3O4/CS NPs) that can be applied to efficient removal of heavy metal ions from aqueous solution. Using a novel impinging stream-rotating packed bed, the continuous preparation of Fe3O4/CS NPs reached a theoretical production rate of 3.43kg/h. The as-prepared Fe3O4/CS NPs were quasi-spherical with average diameter of about 18nm and saturation magnetization of 33.5emu/g. Owing to the strong metal chelating ability of chitosan, the Fe3O4/CS NPs exhibited better adsorption capacity and faster adsorption rates for Pb(II) and Cd(II) than those of pure Fe3O4. The maximum adsorption capacities of Fe3O4/CS NPs for Pb(II) and Cd(II) were 79.24 and 36.42mgg−1, respectively. In addition, the Fe3O4/CS NPs shown excellent reusability after five adsorption-desorption cycles. All the above results provided a potential method for continuously preparing recyclable adsorbent with a wide prospect of application in wastewater treatment.

Significant enhancement on ferrous/persulfate oxidation with epigallocatechin-3-gallate: Simultaneous chelating and reducing

A kind of green tea extract, epigallocatechin-3-gallate (EGCG) was introduced into Fe2+ activated persulfate (Fe2+/PS) system to enhance the degradation efficiency of atrazine. The involvement of EGCG improved atrazine degradation significantly in the pH range of 2.0–7.0, which could be interpreted by the strong reducing and chelating ability of EGCG. EGCG showed a better performance than hydroxylamine and ascorbic acid in modified Fe2+/PS systems, as the presence of EGCG could not only accelerate the transformation of Fe3+ to Fe2+, but prevent the formation of iron precipitation. Batch experiments were conducted and atrazine degradation depended upon the dosage of EGCG, persulfate, Fe2+, and other water quality parameters including initial pH, co-existing anions and natural organic matters. Radical quenching test and electron paramagnetic resonance (EPR) analysis were also performed and results showed that two kinds of radicals (sulfate radicals and hydroxyl radical) were verified to exist and play a significant role on atrazine degradation in the Fe2+/EGCG/PS system. Moreover, possible intermediates of atrazine were identified by HPLC/MS/MS and degradation pathways of atrazine and EGCG were proposed. This study aims to provide a comprehensive understanding on the potential application of EGCG to enhance degradation of refractory organics in water.

Crystal structure of PvdO from Pseudomonas aeruginosa

Pyoverdine I (PVDI) is a water-soluble fluorescein siderophore with strong iron chelating ability from the gram-negative pathogen Pseudomonas aeruginosa PAO1. Compared to common siderophores, PVDI is a relatively large compound whose synthesis requires a group of enzymes with different catalytic activities. In addition to four nonribosomal peptide synthetases (NRPS) which are responsible for the production of the peptide backbone of PVDI, several additional enzymes are associated with the modification of the side chains. PvdO is one of these enzymes and participates in PVDI precursor maturation in the periplasm. We determined the crystal structure of PvdO at 1.24 Å resolution. The PvdO structure shares a common fold with some FGly-generating enzymes (FGE) and is stabilized by Ca2+. However, the catalytic residues in FGE are not observed in PvdO, indicating PvdO adopts a unique catalytic mechanism.

Preparation and evaluation of multidentate ligand-bonded silica chromatographic medium

Iminodisuccinic acid (IDS), a green environment-friendly multidentate chelating agent, was used as a ligand to synthesize IDS-Silica stationary phase under the optimized conditions. The binding capacity of IDS on the stationary phase was measured by potentiometric titration. The chromatographic properties and metal chelating property on IDS-Silica column were investigated. Three standard protein mixtures were separated successfully with IDS-Silica column. The results showed that the IDS-Silica column displayed a typical cation exchange property. The binding characteristics of six different metal ions on IDS-Silica stationary phase were examined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The results validated that the variation of binding capacities of metal ions on the stationary phase were consistent with the chelating stability order of the IDS-Silica column for metal ions. Compared with the other silica columns bonded with the three different aminocarboxyl ligands, the bonding amounts of Cu2+ on IDS-Silica column was the largest, which indicated that IDS had stronger chelating ability for metal ions. This characteristic lays the foundation for IDS as a good chromatographic packing used in the field of immobilized metal affinity chromatography (IMAC), thus probably provides an effective solution to reduce the leaking problem of metal ion from IMAC column during protein elution with one competitive agent.

Antimicrobial and antifouling nanocomposite hydrogels containing polythioether dendron: high-loading silver nanoparticles and controlled particle release

A series of nanocomposite (NC) hydrogels containing dendritic polythioether segments were successfully prepared by free radical copolymerization. Due to the multiple thioether functional groups and the strong chelating ability of the thioether groups with metal elements, these hydrogels showed excellent absorption towards Ag nanoparticles. The size of the Ag nanoparticles (AgNPs) embedded in the hydrogel matrix can be regulated by tuning the content of dendritic segments in the polymer matrix. Small-sized AgNPs were formed with increasing of the content of polythioether dendrons. Besides, the Ag release kinetics was investigated. The hydrogels containing dendrons showed higher AgNPs loading and displayed enhanced retention of nanoparticles as compared with the pristine poly-N-isopropyl acrylamide (PNIPAM) hydrogel. Furthermore, these NC hydrogels, especially those containing dendritic segments, showed much better antimicrobial performance for Escherichia coli and anti-algae performance. These NC hydrogels have promising applications in marine antifouling coating and interfaces of biomaterials.

ChemInform Abstract: Recent Progress in Rhodium‐Catalyzed Hydroaminomethylation

AbstractReview: [52 refs.

Highly selective and sensitive determination of copper ion based on a visual fluorescence method

A novel ratiometric fluorescence sensor for rapid and on-site visual detection of Cu2+ was designed and synthesized by integrating yellow-emission rhodamine fluorophore (RL) and red-emission CdTe@SiO2 QDs. The as-prepared nanohybrid fluorescence sensor shows dual-emissions at 537nm and 654nm under a single excitation at 500nm in the presence of Cu2+. Owing to the strong chelating ability of RL toward Cu2+, the yellow fluorescence of RL could be selectively enhanced while the red fluorescence of CdTe QDs is almost unchanged, leading to an obvious fluorescence color change from red to yellow, which could be used for visual and ratiometric detection of Cu2+. This nanohybrid sensor exhibits excellent selectivity, sensitivity and anti-interference to Cu2+ detection and the detection limit is as low as 8.4nM. Additionally, a simple device test strip for rapid and on-site detection of Cu2+ has been designed by immobilizing the RL-CdTe@SiO2 QDs on a common filter paper. This simple and effective paper-based sensor has a visual detection limit of 0.5μM, showing its promising application for on-site and rapid sensing of Cu2+ in pollution water.

Research on the synthesis and scale inhibition performance of a new terpolymer scale inhibitor.

A new terpolymer named β-CD-MA-SSS was produced using free-radical polymerization of β-cyclodextrin (β-CD), maleic-anhydride (MA) and sodium-styrene-sulfonate (SSS) as monomers, with potassium persulfate (KPS) as initiator. Its performance as a scale inhibitor to prevent deposition of calcium carbonate (CaCO3) has been investigated. Experimental results demonstrated that β-CD-MA-SSS performed excellent scale inhibition and exhibited a high conversion rate under the following conditions: initiator consisting of 6%, molar ratio of reaction monomers SSS:MA = 0.8:1, MA:β-CD = 6:1, reaction temperature of 80 °C, reaction time of 6 h, and dropping time of 40 min when MA was dosed as a substrate, and SSS and KPS were dosed as dropping reactants simultaneously. Use of a Fourier transform infrared spectrometer for this inhibitor showed that the polymerization reaction had taken place with the reaction monomers under the above specified conditions. Scanning electron microscopy indicated that the β-CD-MA-SSS had a strong chelating ability for calcium (Ca(2+)) and a good dispersion ability for calcium carbonate (CaCO3).

Comparison of anti-browning ability and characteristics of the fractionated Maillard reaction products with different polarities

The Maillard reaction products (MRPs) prepared from aqueous equimolar glucose with 1 M cysteine model solution when heated at 110 °C for 1 h was previously recognized as strong browning inhibitors for banana fruit. This study investigated further the anti-browning ability of the fractionated fractions with different polarity using solvent extraction following a ultra-filtration with 3.5 ku MWCO membrane and characteristized antioxidant activity including DPPH• scavenging ability and reducing power, chelating copper activity, inhibitory ability and the inhibitory constants of banana PPO. Extracts with different polarity were obtained by methanol, ethanol, n-butanol and isopropanol, which were designated as MRP(MeOH),MRP(EtOH),MRP(n-BuOH) and MRP(IPA), respectively. Application of the Lineweaver-Burk plotting showed that all MRPs were mixed-type 1 inhibitors whose Kis was larger than corresponding Ki, with Ki values ranging between 0.297 and 0.035 mg/mL MRPs. MRP(EtOH) showed the strongest anti-browning ability from the visual observation, further evidenced by its lowest Ki and IC50 in terms of the inhibition of PPO activity and DPPH• scavenging ability, with a different anti-browning mechanism vs. Na2S2O5. The strong copper chelating ability of the MRPs may account for the antioxidant ability and PPO activity inhibition to an extent. The effective anti-browning components from MRPs in glucose-cysteine model could be enriched by the combination of ultrafitration with ethanol extraction. And the extract may be applicable in food system.

Chelating properties of salicylhydroxamic acid-functionalized polystyrene resins and its application to efficient removal of heavy metal ions from aqueous solutions

Salicylhydroxamic acid(SHA) was covalently bound onto crosslinked polystyrene spheres(CPSs) via the Friedel-Crafts alkylation reaction between chloromethylated CPSs and SHA in the presence of SnCl4 as the Lewis acid catalyst. The resulted SHA-CPSs possessed very strong chelating ability for heavy metal ions. In particular, the saturated adsorption amount of SHA-CPSs for Cu2+ ions could reach as high as 34.2 mg/g at 318 K. The chelating capability of SHA-CPSs towards heavy metal ions was pH and temperature dependent. SHA-CPSs also showed selective metal coordination with the chelating capacity decreasing in the order of Cu2+ >Zn2+>>Pb2+. The adsorption isotherms conformed well to the Langmuir model, and the adsorption process was found to be entropy-driven and endothermic. Besides, SHA-CPSs possessed the excellent reusability.

Neuropharmacological evaluation of selected Jordanian traditional herbal medicines

Numerous medicinal plants have been described in traditional medicine for treatment of dementias, including Alzheimer’s disease (AD). In this study, some of these plants were evaluated in three different types of pharmacological bioassays related to AD pathology to explore the possible mechanisms underpinning their traditional use. Six selected plants were extracted with ethanol and screened in vitro for acetylcholinesterase (AChE) and cycloxygenase-1 (COX-1) enzyme inhibitory activities; in addition, a range of anti-oxidant activities were evaluated. Of the tested plant extracts, Aloysia citrodora and Peganum harmala root and seeds showed inhibitory effect on AChE (IC50 68, 100 and 93 μg/ml,) respectively).. Moreover, A. citrodora appeared to interact reversibly with the enzyme, while P. harmala appeared to show irreversible inhibition. Asphodelus microcarpus, Inula viscosa and A. citrodora displayed COX-1 enzyme inhibitory activity (IC50 34.9, 3.4 and 3.2 μg/ml respectively). DPPH radical scavenging activity was demonstrated by all tested plants. Two extracts in particular (Arbutus andrachne and A. microcarpus) exhibited potent nitric oxide (NO) scavenging activity (IC50 4.5 and 5.0 ug/ml respectively). Four extracts A. citriodora, P. harmala (Root) and (seed) and A. microcarpus exhibited strong metal chelating ability (IC50 4.5, 6.2, 6.5 and 6.7 μg/ml,) respectively). The modest reversible interaction of A. citrodora with AChE, COX-1inhibitory and antioxidant activity, and strong metal chelating ability make this plant a promising candidate for future development in the treatment of AD, either as a whole extract or as individual bioactive constituents. A. andrachne and A. microcarpus extracts should be further evaluated since they exhibited promising NO scavenging activities. Key words: Anti-acetylcholinesterase, anti-inflammatory, anti-oxidant, metal chelating ability, Jordanian medicinal plants, Alzheimer’s disease.

Study on recognition and separation of rare earth ions at picometre scale by using efficient ion-surface imprinted polymer materials

The graft-polymerization of hydroxyethyl methylacrylate (HEMA) on micro-sized silica gel particles was first conducted by initiating of a surface-initiating system, which was constituted by the bonded amino groups on the modified silica gel particles and persulfate in the solution, obtaining the grafted particles PHEMA/SiO2 with a high grafting degree of 40g/100g. Subsequently, 8-hydroxyquinoline as a ligand with strong chelating ability for metal ions was bonded on the side chains of the grafted macromolecule PHEMA through the substitution reaction between 5-chloromethyl-8-hydroxyquinoline (CHQ) and the hydroxyl group of the grafted macromolecule PHEMA, preparing the functional grafted particles HQ-PHEMA/SiO2. On the basis of examining the chelating adsorption property of HQ-PHEMA/SiO2 particles for Pr3+ ion, the Pr3+ ion surface-imprinting was carried out by using the effective surface-imprinting technique of “pre-grafting and post-crosslinking/imprinting” established by our group. During the surface-imprinting process, Pr3+ ion was used as a template ion, and 2,2′-dichlorodiethyl ether was used crosslinked, resulting in the Pr3+ ion surface-imprinted material IIP-HQP/SiO2. The recognition and binding characters of IIP-HQP/SiO2 towards Pr3+ ion were investigated in-depth with La3+ and Ce3+ ions as two contrast ions. The experimental results show that the IIP-HQP/SiO2 particles possess special recognition selectivity and high binding ability for Pr3+ ion. The binding capacity of IIP-HQP/SiO2 for Pr3+ ion reaches 0.13mmol/g, and relative to La3+ and Ce3+ ions, the selectivity coefficients of IIP-HQP/SiO2 for Pr3+ ion are 5.22 and 5.12, respectively. La, Ce and Pr are three neighbouring rare earth elements, and the ion radius differences between La3+, Ce3+ and Pr3+ ions are only in a range of 2–5pm. Obviously, in this investigation, the mutual separation of La3+, Ce3+ and Pr3+ ions at picometre scale is realized successfully by using the ion surface-imprinted polymer material with high performance.

Application of a macromolecular chelating agent in chemical mechanical polishing of copper film under the condition of low pressure and low abrasive concentration

The mechanism of the FA/O chelating agent in the process of chemical mechanical polishing (CMP) is introduced. CMP is carried on a Φ300 mm copper film. The higher polishing rate and lower surface roughness are acquired due to the action of an FA/O chelating agent with an extremely strong chelating ability under the condition of low pressure and low abrasive concentration during the CMP process. According to the results of several kinds of additive interaction curves when the pressure is 13.78 kPa, flow rate is 150 mL/min, and the rotating speed is 55/60 rpm, it can be demonstrated that the FA/O chelating agent plays important role during the CMP process.

Phytic titanium nanomaterialsfor enzyme sensor of hydrogen peroxide

Due to the strong chelating ability between phosphates groups in phytate and metal ions,we synthesized a new porous nanomaterials-titaniumphytate by the method of microware. Then,we tried to employ the nanoporous film of titaniumphytate as a substrate for making the horseradish peroxidase(HRP) based biosensor by drop-coating method and investigate theelectrochemical behavior of enzyme. The UV-vis absorption spectroscopy and electrochemical results showed that this kind of material has a great biological affinity and it can prevent damage to biological activity of enzyme during immobilization. The as-prepared biosensor realized direct electron transfer between the immobilized HRP and glassy carbon electrode and displayed good bioelectrocatalytic ability toward the reduction of H2O2with a linear response to H2O2over a concentration range from 6. 67 × 10-7to 4. 73 × 10-5 mol·L-1,and a detection limit of 4 × 10-7mol·L-1at a signal-to-noise ratio( S / N) = 3. The Michaelis – Menten constant Kapp Mwas estimated to be 0. 036 mmol·L-1. The as prepared biosensor exhibited good reproducibility and stability.

Citrate-Induced Aggregation of Conjugated Polyelectrolytes for Al3+-Ion-Sensing Assays

This work shows the sodium citrate induced efficient interpolymer π-stacking aggregation of the planar cationic conjugated polyelectrolyte poly[{9,9-bis[6'-(N,N-trimethylamino)hexyl]-2,7-fluorenyleneethynylene}-alt-co-(1,4-phenylene)] dibromide (PFE) in aqueous solution, which results in the self-quenching of fluorescence. Using the citrate-induced aggregation properties of PFE and the strong chelation ability of citrate with aluminum ions (Al(3+)), a sensitive and selective Al(3+)-ion detection assay in aqueous solution was developed through monitoring of the fluorescence recovery of PFE. The fluorescence intensity recovery of PFE depends on the concentration of Al(3+) ions, and linear fluorescence recovery was observed in the range of 0.5-9 μM. The limit of detection of this assay is 0.37 μM. Its simplicity and rapidity mean this assay shows promise for the real-time detection of Al(3+).