Acid Copper Research Articles

The Cu(II) Reductase RclA Protects Escherichia coli against the Combination of Hypochlorous Acid and Intracellular Copper.

Enterobacteria, including Escherichia coli, bloom to high levels in the gut during inflammation and strongly contribute to the pathology of inflammatory bowel diseases. To survive in the inflamed gut, E. coli must tolerate high levels of antimicrobial compounds produced by the immune system, including toxic metals like copper and reactive chlorine oxidants such as hypochlorous acid (HOCl). Here, we show that extracellular copper is a potent detoxifier of HOCl and that the widely conserved bacterial HOCl resistance enzyme RclA, which catalyzes the reduction of copper(II) to copper(I), specifically protects E. coli against damage caused by the combination of HOCl and intracellular copper. E. coli lacking RclA was highly sensitive to HOCl when grown in the presence of copper and was defective in colonizing an animal host. Our results indicate that there is unexpected complexity in the interactions between antimicrobial toxins produced by innate immune cells and that bacterial copper status is a key determinant of HOCl resistance and suggest an important and previously unsuspected role for copper redox reactions during inflammation.IMPORTANCE During infection and inflammation, the innate immune system uses antimicrobial compounds to control bacterial populations. These include toxic metals, like copper, and reactive oxidants, including hypochlorous acid (HOCl). We have now found that RclA, a copper(II) reductase strongly induced by HOCl in proinflammatory Escherichia coli and found in many bacteria inhabiting epithelial surfaces, is required for bacteria to resist killing by the combination of intracellular copper and HOCl and plays an important role in colonization of an animal host. This finding indicates that copper redox chemistry plays a critical and previously underappreciated role in bacterial interactions with the innate immune system.

Spectrofluorimetric determination of Cr(VI) and Cr(III) by quenching effect of Cr(III) based on the Cu-CDs with peroxidase-mimicking activity.

The study presents a spectrofluorimetric method for the determination of Cr(III) based on 2,3-diaminophenazine (DAP) as fluorescent nano sensor. With the peroxidase-mimicking activity of copper-doped carbon dots (Cu-CDs), colorless o-phenylenediamine (OPD) was oxidized to fluorescent DAP in the presence of H2O2 via generation of hydroxyl radicals. The Cr(III) was found to decrease the fluorescent intensity of the Cu-CDs-mediated OPD oxidation system. Cr(VI) species were reduced to Cr(III) by employing 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) as the reductant, and a novel spectrofluorimetric method for the highly sensitive detection of speciation Cr(VI) and Cr(III) was developed. The Cu-CDs nanozyme was prepared from ethylenediaminetetraacetic acid copper disodium salt (Na2[Cu (EDTA)]) by one-step pyrolysis method. Under optimal conditions, the fluorescence intensity of DAP is linearly proportional to the Cr(III) ion concentration in the range of 5×10-6 to 1.5×10-4molL-1 and the detection limit is 1.2×10-7molL-1. The method has a good anti-interference performance against some metal ions, such as, Hg2+, Co2+, Cu2+, Mg2+, Ba2+, K+, Mn2+, Ni2+, Al3+, and Fe3+. The proposed method was successfully applied in the determination of Cr(VI) and Cr(III) in water samples.

A Multicentre, Randomised Clinical Trial to Compare a Topical Nitrizinc® Complex Solution Versus Cryotherapy for the Treatment of Anogenital Warts.

IntroductionAnogenital warts (AGW) are a relevant clinical issue in the field of sexually transmitted disease, and to date no treatment provides a satisfactory clearance rate. Treatment can be both medical and surgical, and be provided by a healthcare provider or by the patient. Cryotherapy (CRYO) is among the most common treatments for AGW. Nitrizinc® Complex solution (NZCS) is a solution containing organic acids, nitric acid and zinc and copper salts that is applied topically to warts, producing mummification of the damaged tissue. It is considered to be an effective and well-tolerated treatment for genital and common warts. The aim of our study was to compare NZCS to CRYO in the treatment of AGW.MethodsWe performed a prospective, multicentre, single-blind, randomised, superiority clinical study involving 120 patients, aged 18–55 years, diagnosed with a first episode of AGW, with each patient having from three to ten AGW. The patients were treated either with NZCS or CRYO for a maximum of four treatments. Primary endpoints were: (1) comparison of the clinical efficacy of CRYO and NZCS, based on response to treatment (clearance of AGW) within four treatment sessions; and (2) tolerability, assessed via a short questionnaire at the end of each treatment session. Secondary endpoints were: (1) number of treatments needed for clearance; and (2) recurrence at 1 and 3e months after confirmed clearance. The results were analysed on an intention-to-treat basis.ResultsA complete response was achieved in 89.7% of the NZCS group and in 75.4% of the CRYO group (p = 0.0443). NZCS was found to be better tolerated. There was no difference between the NZCS and CRYO treatment arms in the number of sessions needed to clear the lesions. Recurrence occurred after 1 month in 18.4% of the NZCS group and 38.1% of the CRYO group (p = 0.0356), and after 3 months in 25 and 40.6% of these groups, respectively (p = 0.1479).ConclusionsNitrizinc® Complex solution can be considered to be as effective as CRYO for the treatment of small (< 5 mm) external AGW, with a better tolerability profile and lower rate of recurrence.Trial RegistrationISRCTN identifier, ISRCTN36102369.

Effect of the Surface Morphology of TiO2 Nanotubes on Photocatalytic Efficacy Using Electron-Transfer-Based Assays and Antimicrobial Tests

The application of titanium oxide nanotubes for the removal of contaminants from freshwater is a rapidly growing scientific interest, especially when it comes to water conservation strategies. In this study we employed four different titanium oxide nanotube surfaces, prepared by a two-electrode anodic oxidation. Two of the surfaces were synthesised in aqueous media, while the other two surfaces were synthesised in ethylene glycol. One of the arrays synthesised in the organic medium was impregnated with silver nanoparticles, while the remaining surfaces were not. The chemical reactivity of the various surfaces was assessed using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as free electron sensitive probe molecules, in parallel with tannic acid degradation and copper ion reducing capacity. The potential antimicrobial activity of the surfaces was assessed against a panel of microorganisms composed of yeast, fungi, Gram-positive and Gram-negative bacteria. Field emission scanning electron microscopy revealed that surfaces produced in the aqueous medium had a smaller tube length and a smaller tube diameter. It was noted that one of the materials using sodium sulfate as the supporting electrolyte had the most irregular nanostructure morphology with tubes growing to the side rather than vertically. The structural variation of the surfaces directly reflected both the chemical and biological activity, with the nanotubes formed in ethylene glycol showing the fastest rates in the stabilization of DPPH and ABTS radicals, the fastest tannic acid decomposition under various pH conditions and the fastest metal reducing activity. Furthermore, the surface containing silver and its bare counterpart showed the most effective antimicrobial activity, removing approximately 82% of Gram-negative bacteria, 50% of Gram-positive bacteria, 70% of yeast and 40% of fungi, with Gram-negative bacteria being the most susceptible to these surfaces.

Bee pollen extract as an eco-friendly corrosion inhibitor for pure copper in hydrochloric acid

Herein, bee pollen extract (BPE) was assessed for its performance as a green inhibitor of copper corrosion in acidic media. Gas chromatography mass spectrometry was used to identify the major components of BPE. Multiscale testing techniques, i.e. weight assessment, potentiodynamic polarisation tests, and electrochemical impedance spectroscopy, were employed to explore the corrosion properties of pure copper specimens in 1 M HCl with 0–7 g/L BPE. The adsorption of BPE on the copper surface fitted a Langmuir-type isotherm. BPE behaves as a mixed-type inhibitor that effectively decreases the corrosion of pure copper metal surfaces in 1 M HCl. Increasing the concentration of BPE increases its inhibition efficiency; at 7 g/L BPE, a high inhibition efficiency of 94.5% was attained. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy were employed to analyse the copper surface. The inhibitive properties of BPE on pure copper corrosion are attributed to the adsorption of antioxidants and phenolic compounds on the copper surface. This study provides insight into the efficiency of BPE as a potential corrosion inhibitor of copper in acidic environments.

NOx speciation from copper dissolution in nitric acid/water solutions using FTIR spectroscopy

The speciation of NO2, NO, and N2O gases formed from the dissolution of copper in nitric acid is measured and characterized using Fourier-transform infrared (FTIR) spectroscopy. This study describes analysis of the gas phase species formed and ingrowths of their concentrations as a function of time. Acid concentrations range from 14 to 4 M and the NO2, NO, and N2O are analyzed using FTIR between 1585 and 2209 wavenumbers. The concentrations of the gases range from 0 to 230 ppm and change over time and as a function of acid concentration.

The photoresponsivity of monolayer molybdenum disulfide grown by chemical vapor deposition with different seeding promoters

The performance of photodetectors based on monolayer transition-metal dichalcogenides (TMDCs) varies greatly, even for the same type of devices made of the same material. Here, we compared the performance of phototransistors based on monolayer MoS2 grown by chemical vapor deposition (CVD) with different seeding promoters of perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt (PTAS), copper phthalocyanine (CuPc), and crystal violet, respectively. The device based on MoS2 grown with PTAS has the highest photoresponsivity. This work implies the selection of seeding promoters during the CVD growth of monolayer TMDCs will affect the photodetectors characteristics, which is very important to their applications in optoelectronics.

Low pH in simulated acid rain promotes the toxicity of copper on the physiological performance in Sargassum horneri

In order to investigate the interactive effects of simulated acid rain and copper (Cu) on macroalgae, Sargassum horneri was cultured under pH of 8.2, 5.6, 4.5 and Cu concentrations of 0, 25, 100 μg L-1. Under the medium concentration of Cu, moderate pH mitigated the toxicity of Cu on S. horneri, while the low pH and high Cu concentration reduced the contents of chlorophyll (Chl) a and carotenoids. Furthermore, pH had no interaction with Cu on maximal Chl fluorescence or electron transport efficiency, while effective PSII quantum yield, maximum electron transport rate, and saturating irradiance were obviously affected by pH and Cu, and the interactive effects were significant. Additionally, with the increasing Cu concentration and decreasing pH, nonphotochemical quenching and regulated energy dissipation dropped sharply, while nonregulated energy dissipation increased. Therefore, the high concentration of Cu and low pH had synergistic effects on the photosynthetic performance and growth of S. horneri.

2-(2-chlorophenyl)-1H-Benzimidazole as a New Corrosion Inhibitor for Copper in Sulfuric Acid

2-(2-chlorophenyl)-1H-Benzimidazole as a New Corrosion Inhibitor for Copper in Sulfuric Acid

Optimization of nanofiltration for treatment of acid mine drainage and copper recovery by solvent extraction

The high levels of metals and sulfate ions in acid mine drainage (AMD) constitutes a severe risk to the environment. Our study evaluated at pilot-scale the operational conditions of actual AMD nanofiltration (NF) to recover water and subsequent recovery of copper from the concentrated retentate solution by a solvent extraction (SX) process. NF showed a high copper concentration capacity (0.6 to 2.4 g/L) and good total rejection of species (~82%). While NF treatment allowed a high water recovery of 80%, the polarization resistance could limit its performance. A 1.1 g/L copper retentate solution was selected for use in the SX study to prevent membrane fouling in a possible in-series process (NF-SX). Equilibrium isotherms and McCabe-Thiele diagrams obtained using LIX 84-IC as the extractant indicated that using two countercurrent extraction stages and one stripping stage, it could be recovered 97% of the copper. The use of antiscalants and CaSO4 precipitates formed during NF had a negligible effect on the copper extraction yield by SX. The combined NF-SX results showed that a high recovery of water and copper from AMD is possible. This technology can have an impact on the reduction of freshwater consumption and wastewater treatment costs of mining, and its development is the subject of further research work.

Oxygen-assisted Cathodic Deposition of Copper-Carboxylate Metal–Organic Framework Films

Reductive deposition is an attractive strategy to prepare films of metal–organic frameworks (MOFs), but to cathodically deposit the intergrown dense films of MOFs containing readily reduced metal ions (e.g., Cu2+) without the plating of the corresponding metals still remains a significant challenge. Here, we report the cathodic deposition of metallic copper-free films of two copper-carboxylate MOFs (HKUST-1 and MOF-14). Our strategy relies on the utilization of O2 as probase to electrochemically trigger the crystallization of MOFs. Systematical cyclic voltammetry studies indicate that the favorable synergistic catalytic effects of the acidic copper ions and benzene-1,3,5-tricarboxylic acid ligands on the O2 reduction can positively shift the deposition potential of HKUST-1 significantly to +0.05 V (vs Ag/AgCl), avoiding effectively the plating of metallic copper and facilitating greatly the control over the crystallization kinetics of MOFs. By the further optimization of experimental conditions relevant to reaction temperature, supporting electrolyte, O2 concentration, and working potential, the intergrown dense MOF films with tunable thicknesses were deposited successfully on several commonly used electrodes including the highly oriented pyrolytic graphite, carbon fiber, carbon cloth, and fluorine-doped tin oxide.

Acetic Acid and Ammonium Persulfate Pre-Treated Copper Foil for the Improvement of Graphene Quality, Sensitivity and Specificity of Hall Effect Label-Free DNA Hybridization Detection.

The capability of graphene-based biosensors used to detect biomolecules, such as DNA and cancer marker, is enormously affected by the quality of graphene. In this work, high quality and cleanness graphene were obtained by CVD based on acetic acid (AA) and ammonium persulfate (AP) pretreated copper foil substrate. Hall effect devices were made by three kinds of graphene which were fabricated by CVD using no-treated copper foil, AA pre-treated copper foil and AP pre-treated copper foil. Hall effect devices made of AA pre-treated copper foil CVD graphene and AP pre-treated copper foil CVD graphene can both enhance the sensitivity of graphene-based biosensors for DNA recognition, but the AA pre-treated copper foil CVD graphene improves more (≈4 times). This may be related to the secondary oxidation of AP pre-treated copper foil in the air due to the strong corrosion of ammonium persulfate, which leads to the quality decrease of graphene comparing to acetic acid. Our research provides an efficient method to improve the sensitivity of graphene-based biosensors for DNA recognition and investigates an effect of copper foil oxidation on the growth graphene.

Contrasting soil fungal communities at different habitats in a revegetated copper mine wasteland

Little is known about the responses of soil fungal communities to revegetation of mine wastelands, representing a major gap in the knowledge needed to improve the performances of revegetation schemes for mine wastelands. To shed some light on this matter, we reestablished 4000 m2 of vegetation on an extremely acidic (pH 2.5) copper mine tailings pond and collected soil samples from three different types of habitats: amended layer of the reclaimed tailings (ALRT), unamended layer of the reclaimed tailings (ULRT), and unreclaimed tailings (UT). Soil fungal communities in the 120 samples collected in two consecutive years were characterized via high-throughput sequencing. The fungal diversities at ALRTand ULRT were found to be significantly higher than those at UT. Ascomycota whose relative abundance ranged from 74.5% to 98.4% was the most predominant phylum across all habitats, exhibiting the lowest predominance at ALRT. Two acidophilic fungal genera, Acidomyces and Acidiella, dominated UT with relative abundances being as high as 37.8% and 15.2%, respectively. In contrast, three genera with plant growth-promoting species (Talaromyces, Trichoderma and Penicillium) were abundant at ULRT and ALRT. Remarkably, their relative abundances at ULRT could be up to 29.0%, 26.9% and 9.7%, respectively. The three types of habitats differed considerably in the overall soil fungal community composition at species level, which became more pronounced as time progressed. The abovementioned differences between habitats in soil fungal community features were related to the reduced availability of soil copper and zinc. These results improved our understanding of fungal ecology of mine wastelands.

Electrochemical Investigation of Tetrazolium Violet as a Novel Copper Corrosion Inhibitor in an Acid Environment.

Tetrazolium violet (TZV) is an important pharmaceutical intermediate for the preparation of various medicines, taking into account microbiological studies and TZV as a new inhibitor of heterocyclic compound. The corrosion inhibiting action of TZV for copper in 0.5 M H2SO4 solutions was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy. The corroded copper surfaces were evaluated by scanning electron microscopy. Thereafter, the thermodynamics of TZV adsorption onto copper was computed and evaluated. As a result, the target TZV compound shows great corrosion inhibition performance to protect copper in sulfuric acid. Thermodynamic test results reveal that the Langmuir, Dhar–Flory–Huggins, and Bockris–Swinkels isotherm models provide a better description for the adsorption process of TZV on the metal surface. The calculated values of ΔGads0 indicate a spontaneous adsorption process of TZV on the copper surface accompanied by two kinds of interactions, physical adsorption and chemisorption.

Glycoprotein Mimics with Tunable Functionalization through Global Amino Acid Substitution and Copper Click Chemistry.

Glycoproteins and their mimics are challenging to produce because of their large number of polysaccharide side chains that form a densely grafted protein-polysaccharide brush architecture. Herein a new approach to protein bioconjugate synthesis is demonstrated that can approach the functionalization densities of natural glycoproteins through oligosaccharide grafting. Global amino acid substitution is used to replace the methionine residues in a methionine-enriched elastin-like polypeptide with homopropargylglycine (HPG); the substitution was found to replace 93% of the 41 methionines in the protein sequence as well as broaden and increase the thermoresponsive transition. A series of saccharides were conjugated to the recombinant protein backbones through copper(I)-catalyzed alkyne-azide cycloaddition to determine reactivity trends, with 83-100% glycosylation of HPGs. Only an acetyl-protected sialyllactose moiety showed a lower level of 42% HPG glycosylation that is attributed to steric hindrance. The recombinant glycoproteins reproduced the key biofunctional properties of their natural counterparts such as viral inhibition and lectin binding.

Novel fabrication of a hierarchical structured surface with improved corrosion inhibition by using hydrothermal synthesis and ultraprecision machining

Hydrophobic surfaces are effective on corrosion resistance as the contact with corrosive medium is reduced. In this study, a novel route integrating hydrothermal synthesis with ultraprecision machining (UPM) is reported to prepare a hierarchical cuprous oxide-stearic acid (Cu2O-STA) copper surface. Electrochemical methods were utilized to characterize the corrosion resistance performance. The results indicated that Cu2O-STA surfaces showed good corrosion resistance properties. The enhancement on the properties achieved via introducing UPM fabricated microgrooves was also revealed, by comparing the electrochemical behaviors of Cu2O-STA modified flat samples with the hierarchical surfaces based on Cu2O-STA modified microgrooves.

Temperature-dependent inhibition of PEG in acid copper plating: Theoretical analysis and experiment evidence

Polyethylene glycol (PEG) is widely used in copper plating as an inhibitor. The PEG-Cu+-Cl structure is recognized as the dominant factor in the inhibition mechanism of PEG. In this work, we investigated the influence of temperature on the PEG-Cl inhibition system. Molecular dynamic (MD) simulations based on Density Functional Theory (DFT) were employed to examine the influence of temperature on the adsorption of Cl− on copper surface and the structure of PEG-Cu+-Cl. According to the MD results, it is assumed that there is a negative correlation between the inhibition effect of PEG and the working temperature. The results of corresponding electrochemical measurements are in good agreement with this assumption and the surface morphology analysis of plated copper films confirms this correlation.

Effect of Sodium Dodecyl Sulfate on Mechanical Properties and Electrical Conductivity of Nanotwinned Copper

A compound additive, gelatin (G) + sodium dodecyl sulfate (SDS), was firstly proposed to synthesize nanotwinned Cu with enhanced mechanical properties and electrical conductivity by direct current (DC) electrodeposition. The effect of compound additive in acid copper plating electrolyte on microstructure, nanoindentation hardness, tensile properties and electrical conductivity of electrodeposited copper was investigated. The optimum conditions of DC electrodeposition and deposition rate of electrodeposited copper were evaluated. The results show that the formation of nanotwins and the refinement of grains were enhanced after adding the 20 mg/L SDS + 15 mg/L G of compound additive, in return, which has a positive contribution to the enhanced mechanical properties and electrical conductivity. Tensile strength, hardness and the elongation to failure of electrodeposited Cu were 490 MPa, 1.79 GPa and 7.1%, respectively. The electrical conductivity was 97.4% IACS at room temperature. The enhancement mechanism of tensile properties and electrical conductivity was explained in view of high density of nanotwins.

An Investigation on Anti-Corrosion Properties of Electroplated Copper-Graphene Nano-Composite Films

In this report, graphene sheets used as reinforcements for improvement of anti-corrosion properties have been synthesized by electrochemical intercalation and exfoliation process. The (001) and (002) plane of graphene sheets at a 2θ angle of 13.2 and 26.13 confirmed by X-ray diffraction pattern. High-resolution TEM confirms 8-12 layers of graphene present in the final products. The as-received graphene sheets have been used as reinforcement with copper matrix to synthesize Cu-Gr nanocomposite by electrodeposition method. The results and investigations of Cu-Gr composite thin films deposited from the bath containing 0.1g/L and 0.5g/L graphene concentrations with acidic copper sulfate solution have been compared. The surface morphology and roughness of composites were studied by SEM, AFM and surface profiler. The presence of graphene in Cu-Gr nanocomposite confirmed by EDS analysis. It was observed that the reinforcement particle has increased the mechanical properties of Cu-Gr composite (by 30%) with the addition to the copper matrix. The corrosion resistance of sample was studied by Tafel extrapolation method in standard borate buffer solution. For nanocomposites of 0.5g/L graphene, the values of Tafel constants are, βa=177.37 mv, βc=138.51 mv, Icorr = 9.3165×10-7Amp/cm2, Ecorr = -0.051 volts and corrosion rate 0.01028 mm/a as comparison to the corrosion rate of pure electroplated copper of a value of 0.029 mm/a. The corrosion rate of 0.5g/L Cu-Gr composite was found to be decreased by 2.7 times as compared to pure copper thin films. The structure of the films before and after corrosion was also analyzed to co-relate the electrochemical and structural relationship.

Numerical Simulation of Copper Deposition in the Hull Cell Based on Butler-Volmer Kinetics

In industry plating baths are often characterized by visual evaluation of a Hull cell deposition. In an academic approach, kinetic parameters are determined with cyclic voltammetry to obtain a deeper understanding of reaction mechanisms. In this paper we combine both approaches and show how via numerical simulations based on the boundary element method kinetic parameters can be extracted from Hull cell experiments. This combined method enables a better understanding of industrial electroplating processes without losing important information about coating and visual appearance. The validation is done in an acidic copper system using the kinetic parameters obtained from cyclic voltammetry for simulating the current density distribution and the cell voltage of a Hull cell deposition, followed by a comparison with experimental data. As an additional insight obtained from this study, the presence of O2 lowers the anodic transfer coefficient, while Cl– ions in the electrolyte increase the exchange current density.