Copper-citrate Complex Research Articles

Cu2+-Citrate-Chitosan Complex Nanoparticles for the Chemodynamic Therapy of Lung Cancer.

Lung cancer poses a significant threat to human health. Surgical intervention is the preferred treatment modality for lung cancer, but a large number of patients are deprived of the opportunity for surgery for various reasons and are compelled to undergo radiotherapy and chemotherapy, which entail systemic adverse reactions. In recent years, with the advancement of nanomedicine, chemodynamic therapy (CDT) based on free radicals has been extensively investigated. In this study, we fabricated copper-citrate-chitosan composite nanoparticles (CuCC NPs) by encapsulating copper-citrate complexes with natural chitosan polymers, resulting in a substantial reduction in the biotoxicity of copper ions. The CuCC NPs selectively accumulated in tumor tissues through the enhanced permeability and retention effect (EPR) and gradually degraded within the acidic and glutathione (GSH)-rich microenvironment of the tumor, thereby releasing the loaded copper ions. Through CDT, the copper ions converted the overexpressed hydrogen peroxide (H2O2) in the tumor tissue into hydroxyl radicals (•OH), leading to the eradication of tumor cells. In animal experiments, CuCC NPs exhibited remarkable efficacy in CDT. Further histopathological and hematological analyses demonstrated that CuCC NPs could induce substantial apoptosis in tumor tissues while maintaining an extremely high level of safety.

Selective Chelating Resin for Copper Removal and Recovery in Aqueous Acidic Solution Generated from Synthetic Copper-Citrate Complexes from Bioleaching of E-waste

This research focused on batch experiment using a new generation of chelating resins via an ion exchange process to describe the metabolic adsorption and desorption capacity onto iminodiacetic acid/Chelex 100, bis-pyridylmethyl amine/Dowex m4195, and aminomethyl phosphonic/Lewatit TP260 functional groups in bioleaching. The results showed that Dowex m4195 had the highest performance of adsorption capacity for copper removal in both H+-form and Na+-form. Results for Lewatit TP260 and Chelex 100 revealed lower adsorption performance than results for Dowex m4195. The investigation of desorption from chelating resins was carried out, and it was found that 2 M ammonium hydroxide concentration provided the best desorption capacity of about 64.86% for the H+-form Dowex m4195 followed by 52.55% with 2 M sulfuric acid. Lewatit with 2 M hydrochloric acid gave the best desorption performance in Na+-form while Chelex 100 using hydrochloric at 1 M and 2 M provided similar results in terms of the H+-form and Na+-form. As aspects of the selective chelating resins for copper (II) ions in aqueous acidic solution generated from synthetic copper-citrate complexes from bioleaching of e-waste were considered, H+-form Dowex m4195 was a good performer in adsorption using ammonium hydroxide for the desorption. However, chelating resins used were subsequently reused for more than five cycles with an acidic and basic solution. It can be concluded from these results that selective chelating resins could be used as an alternative for the treatment of copper (II) ions contained in e-waste or application to other divalent metals in wastewater for sustainable water and adsorbent reuse as circular economy.

Insights into enhanced electrokinetic remediation of copper-contaminated soil using a novel conductive membrane based on nanoparticles.

Electrokinetic remediation is a process in which a direct electric current is applied across a section of contaminated soil to remove metals. To improve the electrokinetic remediation in this study, a conductive membrane was fabricated via in situ chemical polymerization employing pyrrole and copper oxide nanoparticles. The fabricated membrane was placed in an electric field as part of the electrode structure. A physical model was constructed and filled with copper-contaminated kaolinite in the concentration of 200mg/kg. To control the pH, 0.1M citric acid and 0.01M potassium chloride were used as the electrolyte solutions. Experimental parameters such as voltage, current, pH, EC, drained flow, and copper concentration were measured. The results showed that the minimum surface resistivity of the fabricated membrane under a maximum pressure of 8.2kPa was 2.55 kΩ/m2. The experimental results demonstrated that the use of citric acid as an electrolyte was more useful to desorb the copper due to the formation of the copper-citrate complex. When employing the fabricated membrane, the copper removal increased from 13% (in CT-2) to 63% (in GM-2), while the removal of copper using potassium chloride electrolyte increased from 42% (in CT-1) to 52% (in GM-1). The highest power consumption was obtained in experiments using citric acid. Due to the higher removal efficiency of copper in GM-2, the energy utilization efficiency (β) increased and reached 29.9 near β value of GM-1 with the lowest power consumption.

Copper supported on acid-activated vermiculite as an efficient and recyclable catalyst for the Biginelli reaction: a green approach

AbstractThe synthesis of copper citrate complex supported on acid-activated vermiculite was investigated with a view to preparing an efficient, mild, robust and recyclable catalyst for the Biginelli reaction. The new catalyst was characterized by X-ray fluorescence (XRF), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). Copper citrate supported over activated vermiculite (AAVrm-Cu2) showed good catalytic activity in the synthesis of 3,4-dihydropyrimidinones. The catalyst can be separated easily from the reaction mixture by filtration and retains its catalytic activity for up to five cycles of reaction with no apparent decrease in yield.

Shape-controlled preparation of Cu2O crystals and their growth mechanism

A facile solution-phase method is presented via reducing the copper-citrate complex solution with glucose to synthesis Cu2O crystals with different shapes from cubes, truncated octahedral, and finally to octahedral by adjusting the reaction conditions including Polyvinyl Pyrrolidone (PVP) concentration, reaction time, reaction temperature and so on. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) have been applied to analyze the properties of the crystals with various architectures. The comparison shows that the growth mechanism is possibly based on the variation of the ratio (R) of the Cu2O crystal growth rates along the {100} and {111} direction.

Hollow TiO2 nanocages with rubik-like structure for high-performance photocatalysts

Hollow TiO2 nanocages with rubik-like structure were synthesized via a combined hydrolysis/hydrothermal method. Firstly, highly uniform Cu2O nanocubes covered by TiO2 layer were prepared by hydrothermal hydrolysis of (NH4)2TiF6 following by reducing copper-citrate complex with ascorbic acid. The Cu2O core templates could be easily removed in dilute HCl solution to form a hollow rubik-like structure. The obtained TiO2 nanocages show promising efficiency in the photocatalytic degradation of phenol pollutions.

Electrodeposition of copper into trenches from a citrate plating bath

The electrodeposition of copper from a citrate solution has been investigated as a function of pH of the plating bath, and applied to the filling of 500 nm trenches. Speciation diagrams of copper in aqueous citrate solution were used to select four deposition baths with different dominant copper-citrate complexes, which was corroborated using UV–vis spectrophotometry. The electrochemical properties of the plating baths were determined in order to relate the deposition kinetics to the morphology of deposits in trenches. SEM images illustrate that the plating bath at pH 3.1, where only mild inhibition of the deposition kinetics is observed, is capable of adequately filling the trenches.

Investigation of photoelectrocatalytic activity of Cu 2O nanoparticles for p-nitrophenol using rotating ring-disk electrode and application for electrocatalytic determination

A cuprous oxide (Cu 2O) nanoparticles modified Pt rotating ring-disk electrode (RRDE) was successfully fabricated, and the electrocatalytic determination of p-nitrophenol (PNP) using this electrode was developed. Cu 2O nanoparticles were obtained by reducing the copper–citrate complex with hydrazine hydrate (N 2H 4·H 2O) in a template-free process. The hydrodynamic differential pulse voltammetry (HDPV) technique was applied for in situ monitor the photoelectrochemical behavior of PNP under visible light using nano-Cu 2O modified Pt RRDE as working electrode. PNP undergoes photoelectrocatalytic degradation on nano-Cu 2O modified disk to give electroactive p-hydroxylamino phenol species which is compulsive transported and can only be detected at ring electrode at around 0.05 V with oxidation signal. The effects of illumination time, applied bias potential, rotation rates and pH of the reaction medium have been discussed. Under optimized conditions for electrocatalytic determination, the anodic current is linear with PNP concentration in the range of 1.0 × 10 −5 to 1.0 × 10 −3 M, with a detection limit of 1.0 × 10 −7 M and good precision (RSD = 2.8%, n = 10). The detection limit could be improved to 1.0 × 10 −8 M by given illumination time. The proposed nano-Cu 2O modified RRDE can be potentially applied for electrochemical detection of p-nitrophenol. And it also indicated that modified RRDE technique is a promising way for photoelecrocatalytic degradation and mechanism analysis of organic pollutants.

DIRECTING THE BRANCHING GROWTH OF CUPROUS OXIDE BY OH- IONS

The effect of OH - ions on the branching growth of cuprous oxide microcrystals was systematically studied by a reduction route, where copper-citrate complexes were reduced by glucose under alkaline conditions. Different copper salts including Cu ( NO 3)2, CuCl 2, CuSO 4, and Cu ( Ac )2 were used in this work. The results indicate that the Cu 2 O branching growth habit is closely correlated to the concentration of OH - ions, which plays an important role in directing the diffusion-limited branching growth of Cu 2 O and influencing the reduction power of glucose. A variety of Cu 2 O branching patterns including 6-pod, 8-pod and 24-pod branches, have been achieved without using template and surfactant. The current method can provide a good platform for studying the growth mechanism of microcrystal branching patterns.

Morphology Evolution of Cu2O from Octahedra to Hollow Structures

Octahedral Cu2O crystals with all edge length about I pill were synthesized by reducing it copper-citrate complex With glucose. The morphology and Structure Of Cu2O particles were greatly affected by the concentration of glucose, reaction temperature, and time. When the concert tralion of glucose increased from 0.6 to 1.6 M, the morphology of Cu2O Could be changed from octahedral single crystals to spherical polycrystals. When the reaction time was prolonged from 6 to 36 11, solid Cu2O Octahedra could be changed to it mixture of hollow Cu2O octahedra and irregular Cu particles. After removing Cu particles. pure Cu2O hollow Octahedra could be obtained. The formation mechanism Of hollow Cu2O octahedra was discussed. Similarly, hollow Cu2O spheres could also be obtained using this method. The prepared hollow Octahedra[ Cu2O Particles exhibited higher pholoocatalytic activity for photodegradation of p-nitrophenol aqueous Solution under visible-light illumination thim other Cu2O particles with different morphologies (hollow spheres, solid octahedra, and solid spheres).

Adsorption of copper–citrate complexes on chitosan: Equilibrium modeling

The effects of complexes on the adsorption of copper from citrate solutions using chitosan were investigated. Various copper to citrate ratios and solution pHs were used to determine the copper adsorption capacity on the chitosan and a mathematical model was developed to simulate the copper adsorption process. According to the model, the three parameters influencing the copper adsorption capacity are the fraction of protonated amine groups ( RNH 3 + ) , the fraction of anionic copper–citrate complexes (CuL − and CuL 2 4 - ), and the fraction of anionic citrate complexes (HL 2−, H 2L −, and L 3−). The copper adsorption capacities onto chitosan at varying copper–citrate ratios and solution pHs can be predicted by the mathematical model. With such a model to facilitate understand the copper adsorption mechanisms at varying copper–citrate ratios and solution pHs, the copper adsorption efficiency can be increased by the adjustment of the copper–citrate ratio and solution pH.

Morphology Control of Copper Growth on TiN and TaN Diffusion Barriers in Seedless Copper Electrodeposition

Growth behavior of copper on and diffusion barriers according to the compositional change of copper-citrate complex baths was studied in seedless copper electrochemical deposition. The peak potentials of cyclic voltammograms in the forward potential sweep were dependent on the concentration ratio of and in the baths. For the bath of , when one-step deposition of copper was performed at a peak potential for competitive reduction of both and ions, the 3D island growth of copper including lamella-like structure was shown. A peak for reduction and a peak for reduction existed separately for the bath of . Two-step deposition of copper in this bath gave birth to the 3D island plus layer-by-layer growth of copper. Interfacial adhesion between copper and was measured as 12 and , respectively, for both deposition conditions. The electrical resistivity of copper films grown by two-step deposition was lower than that by one-step deposition for the same thickness.

Quantitative Measurement of Interfacial Adhesion Between Seedless Electrodeposited Copper and Tantalum-Based Diffusion Barriers for Microelectronics

Seedless electrochemical deposition (ECD) can generate good adhesion of copper on TaN and Ta diffusion barriers using a saturated KOH solution and a copper-citrate complex electrolyte. The interfacial fracture energy of the Cu/TaN or Ta interface was quantitatively measured by four-point bending method. The load increased linearly with interfacial crack growth due to the plasticity of ductile copper and the elastic bending of the Si substrate. The delamination energy was proportional to the thickness of seedless ECD copper, which was in the range of 180-980 nm. The delamination energy in the steady state, G ss , of 5-24 J m -2 was attained.

Preparation and electrochemical performances of cubic shape Cu 2O as anode material for lithium ion batteries

Cubic and star-shaped crystalline Cu 2O particles were synthesized by reducing the copper citrate complex solution with glucose. The microstructure and morphology of the Cu 2O were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the Cu 2O as anode materials for lithium ion batteries were measured by galvanostatic charge–discharge tests. The as-synthesized Cu 2O particles were 1–2 μm with narrow distribution and the shape of Cu 2O particles had an effect on the electrochemical properties. The cubic Cu 2O particles delivered a higher reversible discharge capacity (390 mAh g −1) than the star-shaped Cu 2O, and also exhibited good cyclability. The star-shaped Cu 2O particles presented poor cyclability due to pulverization and deterioration after cycling, but the morphology of the cubic Cu 2O particles was stable even after 50 cycles.

Multiple Bath Usage for Adhesion Enhancement of Directly Electrodeposited Copper on TaN

Copper films were directly electrodeposited on a TaN diffusion barrier from specially designed electrolytes that contribute to good adhesion between copper and TaN. A very stable oxide film formed on the TaN surface when TaN was exposed in air. The tantalum oxide layer was removed by applying an anodic potential in a saturated KOH solution. The TaN surface in oxide free condition serves as an energetically favorable platform for highly adherent copper deposition in a copper-citrate complex solution. Careful selection of electrochemical parameters such as chemical composition, current, applying voltage, and time led to quality copper deposits on TaN with strong adhesion.

Electrodialytic remediation of copper mine tailings: Comparing different operational conditions

This work compares and evaluates sixteen electrodialytic laboratory remediation experiments on copper mine tailings. Different parameters were analyzed, such as remediation time, voltage drop, addition of desorbing agents, and the use of pulsed electrical fields. The results show that electric current could remove copper from watery tailings slowly. With addition of sulphuric acid, the process was improved due to a pH decrease from 6.7 to around 4, and the copper by this reason was released in the solution. Moreover, with citric acid addition the process was further improved due to a formation of copper citrate complexes. Using pulsed electric fields the remediation process with sulphuric acid addition was also improved by a decrease in the polarization cell. Main results: considering remediation with watery tailing as the base line, for three weeks experiments no copper removal was observed, adding sulphuric acid total copper removal reached 39%. Adding citric acid, total copper removal was improved in terms of remediation time: after 5 h experiment copper removal was 16% instead of 9% obtained after 72 h with sulphuric acid addition. Using pulsed electric fields total copper removal was also improved: for 72 h experiment the total copper removal was doubled (from 9% to 19%) compared to DC electric fields.

Electrodialytic Remediation of Copper Mine Tailings: Sulphuric and Citric Acid Addition

Decades of mining activities in Chile have generated large amounts of solid waste, which have been deposited in mine tailing impoundments. These impoundments cause concern due to dam failures or natural leaching to groundwater and rivers. This work shows the laboratory results of 11 electrodialytic remediation experiments on copper mine tailings with the addition of sulphuric and citric acid. Comparing this to electrodialytic remediation with watery tailing, both acids enhanced the process. However, with citric acid addition the process was further enhanced because besides the pH decrease a formation of copper citrate complexes occurred. The maximum copper removal reached in the anode side of the remediation cell was 53% with sulphuric acid in 504 h and 35% with citric acid in only 40 h, both experiments at 20 V treating approximately 1.7 kg mine tailing on dry basis.

Complexation Chemistry in Copper Plating from Citrate Baths

An experimental and theoretical study of the influence of solution chemistry on the electrodeposition of copper from complexing citrate baths is proposed and discussed. The behavior of the system is described in terms of the relative distribution of various copper-citrate complexes, combined with a model mechanism for electrodeposition kinetics involving an adsorbed blocking intermediate. Studies of partial-current polarization curves for copper deposition over a wide range of solution pH and free citrate concentration substantiate the mechanism and offer convincing evidence for the significant role of solution chemistry in the electroreduction process. In addition to the copper system, the mechanism proposed offers a framework that may be useful for the study of other metals and alloys electrodeposited from complexing baths containing citrate or citrate-like molecules. © 2004 The Electrochemical Society. All rights reserved.

Lipid Peroxidation in the Presence of Albumin, Inhibitory and Prooxidative Effects

Oxidative modifications of LDL are involved in atherogenesis. Previously we have developed a simple assay to evaluate the susceptibility of lipids to copper-induced peroxidation in the relatively natural milieu of unfractionated serum in the presence of excess citrate. Based on our previous results we have proposed that the inducer of peroxidation in our optimized assay is a copper-citrate complex. Recent investigations indicate that under certain conditions a copper-albumin complex may induce peroxidation of ascorbate. Two different complexes may be formed in albumin-containing systems (e.g. serum) namely 1:1 and 2:1 copper-albumin complexes. The aim of the present work was to evaluate the possibility that at least one of these complexes may be responsible for the induction of peroxidation of lipids in lipidic systems containing copper and albumin, including our optimized assay. Towards this end, we have investigated the dependence of copper-induced peroxidation on the concentration of added albumin in lipidic systems in the absence and presence of citrate. In all the systems investigated in this study (PLPC liposomes, LDL, HDL and mixtures of HDL and LDL) we found that at low concentrations of free copper (e.g. in the presence of excess citrate) the 2:1 copper-albumin complex is redox-active and that this complex is the major contributor to the initiation of lipid peroxidation in these systems and in our optimized assay. The possible relevance of the induction of peroxidation in vivo by the latter complex has yet to be studied. <footnote id="fn1"><no>*</no>This work was performed in partial fulfillment of the requirements for a Ph.D. degree of Dorit Samocha-Bonet, Sackler Faculty of Medicine, Tel-Aviv University, Israel. </footnote>

Copper sorption by chitosan in the presence of citrate ions: influence of metal speciation on sorption mechanism and uptake capacities

The presence of organic ligands in a solution containing metal ions modifies metal speciation, which in turn changes the sorption mechanism, optimum pH range and maximum sorption capacity. The present work investigates the sorption of copper by chitosan in the presence of citrate at different metal/ligand ratios. Copper uptake in acidic solution takes place through electrostatic attraction between the protonated amine groups of chitosan and anionic copper-citrate complexes (mainly Cu(OH)L 2− but also a small fraction of CuL −). Sorption was negligible below pH 3 due to competition from dissociated anionic ligand and counter ions brought about by dissociation of the acid used for pH control. Actually, copper sorption begins to be significant when the fraction of anionic copper-complexes exceeds that of anionic copper-free ligand. So sorption capacity strongly increases up to pH 4.5–5.5. Above pH 5.5, the progressive decrease of amine protonation leads to a linear decrease in sorption capacity. An excess of ligand leads to an increase in the fraction of free dissociated (anionic) ligand that may compete for electrostatic attraction on protonated amine groups and therefore leads to a decrease in sorption capacities.