Response Of Cu Research Articles

A highly selective fluorescent chemosensor based on thio-β-enaminone analog with a turn-on response for Cu(II) in aqueous media

Novel chemosensor, 1,1,2-trimethyl-1H-benzo[e]indoline based thio-β-enaminone (TBE) was developed with excellent sensitivity and selectivity for Cu2+ ions. In comparison with different cations (Na+, Mg2+, Al3+, K+, Ca2+, Mn2+, Co2+, Ni2+, Zn2+, Cd2+, Ba2+, La3+, Hg2+, Pb2+), TBE gave pronounced 20-fold fluorescence enhancement for Cu2+ ions, which remained unaffected in presence of other interfering metal ions. The ratiometric binding of TBE–Cu2+ complex determined from Job's plot gave 1:1 interaction, which was confirmed by ESI-MS. Binding of Cu2+ ions to TBE was studied over the wide pH range and the result demonstrated maximum fluorescence enhancement in the pH range of 3.0–10. The binding association constant (Ka) value determined from Benesi–Hildebrand equation was 1.10×104M−1. The high detection limit in micromolar range (8.2×10−7M) for Cu2+ ions makes TBE a suitable candidate for the development of a potential probe. Applicability of TBE to detect Cu2+ ions in human serum and tap water has been demonstrated.

Facile and quantitative electrochemical detection of yeast cell apoptosis

An electrochemical method based on square wave anodic stripping voltammetry (SWASV) was developed to detect the apoptosis of yeast cells conveniently and quantitatively through the high affinity between Cu2+ and phosphatidylserine (PS) translocated from the inner to the outer plasma membrane of the apoptotic cells. The combination of negatively charged PS and Cu2+ could decrease the electrochemical response of Cu2+ on the electrode. The results showed that the apoptotic rates of cells could be detected quantitatively through the variations of peak currents of Cu2+ by SWASV, and agreed well with those obtained through traditional flow cytometry detection. This work thus may provide a novel, simple, immediate and accurate detection method for cell apoptosis.

Naked eye sensing of toxic metal ions in aqueous medium using thiophene‐based ligands and its application in living cells

Thiophene-based diimine (R1) and monoimine (R2) were synthesized in a single step, and their cation binding affinity was tested using colorimetric and UV-vis spectral studies. R1 selectively shows a colorimetric turn-on response for Pb(2+), Hg(2+) ions and colorimetric turn-off with Sn(2+) ions, and R2 shows visual response for Cu(2+) and Hg(2+) over other examined metal ions in aqueous medium. R1 forms 1:1 complex with Pb(2+), Hg(2+), and Sn(2+) and exhibits fluorescence quenching, whereas R2 shows 2:1 complex with Hg(2+), Cu(2+) and shows fluorescence enhancement. The structural and electronic properties of the sensors and their metal complexes were also investigated using Density Functional Theory calculations. R2 was also successfully demonstrated as a fluorescent probe for detecting Cu(2+) ions in living cells.

Mechanism of electrochemically polymerised acid chrome blue K and its application in copper ion detection

The possible mechanism of electrochemically polymerised acid chrome blue K (poly(ACBK)) was first investigated by in-situ electron spin resonance (ESR) spectroelectrochemistry, attenuated total reflection (ATR)-FTIR spectroscopy, theoretical calculation and electrochemical method in detail. Then an anodic stripping voltammetric method for the determination of copper was established by using a glassy carbon electrode modified with poly(ACBK) (poly(ACBK)/GCE). After an accumulation time of 100 s at −0.45 V (vs SCE), a linear response for Cu2+ was obtained in the range from 2.0 × 10−8–1.0 × 10−5 molL−1 with the detection limit of 7.0 × 10−9 molL−1 (S/N = 3). Finally, this proposed electrochemical method was successfully applied to determine the copper contents in water and food samples with satisfactory results.

Chemically modified multiwalled carbon nanotube carbon paste electrode for copper determination

A new Cu2+ carbon paste electrode based on incorporation of new CPE via chemically modified multiwalled carbon nanotube (CMMWCNT) on the graphite matrices has been constructed. The surface of MWCNT was modified by performing a coupled reaction between trimethoxysilylpropylethilendiamine (TMSPEDA) and 2-hydroxybenzaldehyde (2-HBA). This new material was characterized with different techniques such as FT-IR, SEM and BET analysis. The influence of variables including sodium tetraphenylborate (NaTPB), graphite powder, Nujol, amount of MWCNT–SPAEIMP and Ag nano particles loaded on AC on the electrode response was studied and optimized. At optimum values of variables set as carbon powder, carrier, NaTPB and Nujol, the response of Cu2+ selective electrodes in the absence and presence of Ag-NP-AC was linear in a concentration range of 5.0×10−6–1.0×10−1 and 5.0×10−7–1.0×10−1 molL−1 with slope 29.93 and 29.11mV and with detection limit of 3.2×10−6 and 2.5×10−7. The good performance of electrode viz. reasonable wide pH range (2.0–5.5), fast response time (<15s) and adequate life time (2months) in addition to low RSD (<4%) shows the utility of the proposed electrodes for Cu2+ ion content quantification in various situations. The moderate selectivity coefficient evaluated by the separation solution method (SSM) and fixed interference method (FIM) indicates efficiently the discriminating ability of proposed electrode for copper ion evaluation.

A new way of synthesis nanohybrid cation-exchanger applicable for membrane electrode

A novel polymeric composite namely, PANI-PW/Ag (silver doped polyaniline phosphotungstate) was expediently obtained by sol-gel method. PANI-PW/Ag was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, UV–vis spectrophotometry, scanning electron microscopy, and thermogravimertic analysis. On the basis of ion exchange capacity and distribution studies, PANI-PW/Ag, highly selective and sensitive to Cu(II), was used for the preparation of ion selective membrane for Cu(II). The electrode exhibits good potentiometric response for Cu(II) over a wide concentration range (1.0 × 10−1−5.0 × 10−6 mol) with Nernstian slope of 27.8 mV per decade. Response time of the electrode is 9 s and it could be used for a period of 3 month and exhibits good selectivity toward Cu2+ in comparison to alkali, alkaline earth, transition, and heavy metal ions, with no interference caused by other heavy metals. POLYM. COMPOS., 35:1436–1443, 2014. © 2013 Society of Plastics Engineers

A bifunctional, colorimetric and fluorescent probe for recognition of Cu2+ and Hg2+ and its application in molecular logic gate

A bifunctional probe 1 with iminocoumarin scaffold demonstrated different responses for Cu2+ and Hg2+. In fluorescence mode of probe 1, the intensity at 528 nm was quenched severely upon the addition of Cu2+ or Hg2+. Meanwhile, a new fluorescence band at 574 nm appeared in the case of Hg2+. In its UV-Vis absorption mode, significant hypochromic shift for Cu2+ and bathochromic shift for Hg2+ occurred, which are in agreement with the observation of distinct color changes. In addition, probe 1 can be used for the construction of a molecular logic gate with NOR and INHIBIT logic functions.

Recyclable sensitive fluorimetric detection of specific metal ions using a functionalized PEG-PS resin with a fluorescent peptide sensor

Previously, we synthesized a fluorescent peptide sensor consisting of heptapeptide for Cu(II) and Zn(II) ions, respectively. The peptide sensor detected Cu(II) ions by turn off response and Zn(II) ions by turn on response among 13 metal ions in aqueous solutions. In the present study, we prepared a functionalized resin by immobilization of the fluorescent peptide sensor into PEG-PS resin beads and investigated the sensing ability for the metal ions in aqueous solutions. The functionalized resin was easily used for detecting heavy metal ions in aqueous solutions using spectrofluorometer with stirrer. The functionalized resin with the peptide sensor showed a selective response to Cu(II) and Zn(II) ions among 13 metal ions in aqueous solutions. The functionalized resin with the peptide sensor, showed a turn off response to Cu(II) and a turn on response to Zn(II) ions in aqueous solutions. The resin showed a very sensitive response to Cu(II) and Zn(II) ions; about 1 equiv of the metal ions was enough to saturate the fluorescent change of the resin. Furthermore, the recycle of the resin bead for detecting metal ions was demonstrated by simply washing of the resin with EDTA solution and fluorescent response for Cu(II) ions.

On the role of Icosahedral-like clusters in the solidification and the mechanical response of Cu–Zr metallic glasses by Molecular Dynamics simulations and Density Functional Theory computations

Cu–Zr Metallic glasses (MG) are considered to be composed of Icosahedral-like (ICO) clusters that may be distorted, truncated and/or interconnected. Aiming in gaining insight on the role of these units in the solidification-glass formation processes, as well as under mechanical solicitation, we performed detailed analysis of the electronic density of states, based on the Density Functional Theory, of the basic ICO-like clusters that were extracted from Cu65Zr35 equilibrium Molecular Dynamics (MD) configurations at various temperatures within the range from 2000 K to 300 K. In line with previous studies, we found that the d valence electrons of the Zr shell atoms occupy states close to the Fermi level, while s–s and d–s electronic hybridizations of the Cu-core/Cu-shell with the Cu shell atoms, respectively, occur at lower energy states and account for the deformation of the clusters, which is exclusively accomplished by these Cu–Cu distortions. Moreover, we found that upon quenching the mean atomic distances of the ICOs are decreasing due to shortening of the Cu-core/shell – Cu shell bonds, resulting in shifts of the corresponding states towards lower energies. Interestingly, it came out that the temperature dependence of these energies is linear, exhibiting slope changes at the melting and glass transition points. We applied the same analysis on ICOs extracted from Cu50Zr50 MD configurations under tensile solicitation from where we deduced the alterations that are caused in the electronic densities of states. These results could be of use for the understanding of the bonding characteristics of Cu–Zr model MGs and the mechanisms for the accommodation of the mechanical deformation.

Microstructure and properties of Cu–2.8Ni–0.6Si alloy

The phase transformation behavior and heat treatment response of Cu–2.8Ni–0.6Si (wt%) alloy subjected to different heat treatments were studied by X-ray diffraction, transmission electron microscopy observation, and measurement of hardness and electrical conductivity. The variation of hardness and electrical conductivity of the alloy was measured as a function of aging time. On aging at the temperature below T R (500–550 °C) in Cu–2.8Ni–0.6Si alloy, the transformation undergoes spinodal decomposition, DO22 ordering, and δ-Ni2Si phase. On aging at the temperature above T R (500–550 °C), the transformation products were precipitations of δ-Ni2Si. The free energy versus composition curves were employed to explain the microstructure observations.

Dielectric properties investigation of Cu2O/ZnO heterojunction thin films by electrodeposition

► Bottom-up self-assembly Cu 2 O/ZnO heterojunction was fabricated by electrochemical deposition on indium tin oxide (ITO) flexible substrate (polyethylene terephthalate-PET). ► The dielectric response of Cu 2 O/ZnO heterojunction thin films had been investigated. ► The universal dielectric response was used to investigate the hopping behavior in Cu 2 O/ZnO heterojunction. Structures and morphologies of the Cu 2 O/ZnO heterojunction electrodeposited on indium tin oxide (ITO) flexible substrate (polyethylene terephthalate-PET) were investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM), high resolution transmission electron microscopy (HRTEM), respectively. The dielectric response of bottom-up self-assembly Cu 2 O/ZnO heterojunction was investigated. The low frequency dielectric dispersion (LFDD) was observed. The universal dielectric response (UDR) was used to investigate the frequency dependence of dielectric response for Cu 2 O/ZnO heterojunction, which was attributed to the long range and the short range hopping charge carriers at the low frequency and the high frequency region, respectively.

Structural, photoelectrical characterization of Cu(InAl)Se2 thin films and the fabrication of Cu(InAl)Se2 based solar cells

Films of Cu(InAl)Se2 were deposited onto glass substrates by SILAR (successive ionic layer adsorption and reaction) method. All the deposited films were found to be polycrystalline in nature exhibiting the chalcopyrite structure with the crystallite orientation along (112), (220/204) and (116/312) directions. The photocurrent was found to increase with increase in film thickness and also with increase of light intensity. Photocurrent spectra showed a peak related to the band-to-band transition. The spectral response of Cu(InAl)Se2 thin films was studied by allowing the radiation to pass through a series of interference filters in the wavelength range 300 to 1200 nm. Films of higher thickness exhibited higher photosensitivity while lower thickness films exhibited moderate photosensitivity. Cu(InAl)Se2-based solar cells with different types of buffer layers such as CdS, CdS:Cu, CdS:In were fabricated. The current and voltage were measured using an optical power meter and an electrometer and the fabricated solar cells were illuminated using 100 mW/cm2 white light under AM1 conditions.

Analysis of procalcitonin and CRP concentrations in serum of patients with chronic spontaneous urticaria

BackgroundOur previous findings showed the importance of analysing the peripheral markers of acute phase response (APR) activation, C-reactive protein (CRP) and IL-6 in the context of urticaria activity and severity. However, these biomarkers do not reliably differentiate between APR to infectious and the disease severity.AimIn order to investigate a possible association between the immune-inflammatory activation markers CRP and procalcitonin (PCT).MethodsSerum PCT and CRP concentrations were measured in patients with CU of varying severity as well as in healthy subjects.ResultsSerum PCT and CRP concentrations were significantly increased in more severe CU patients when compared to healthy controls and mild CU, and within the CU population there was a significant correlation between concentrations of PCT and CRP. Serum PCT concentrations remained within normal ranges in most CU patients and were only slightly elevated in some severe CU cases.ConclusionsPCT serum concentration may be only slightly elevated in some cases of severe CU. Upregulation of PCT synthesis accompanied by parallel changes in CRP concentration reflects a low-grade systemic inflammatory response in CU. PCT should be considered as a better marker than CRP to distinguish between APR to infection and an active non-specific urticarial inflammation.

A “Turn-On” Fluorescent Chemosensor Based on Peptidase for Detecting Copper(II)

A new fluorescent chemosensor for Cu(II) ions was designed and synthesized on the basis of the sequence-specific cleavage of the peptide bond by the peptidase (metal or metal complexes). In the chemosensor system, the substrate was labeled with a FAM fluorophore (6-carboxyfluorescein) at the N-terminal and with a Dabcyl quencher 4-(4'-dimethylaminophenylazo)benzoic acid at the ε-N of C-terminal Lys. In the presence of Cu(II), the substrate strand is cleaved, and the release of the cleaved fragment results in a significant fluorescence increase. The design was aided by the FRET study that showed a "turn-on" response for Cu(II) in an aqueous medium. Under optimum conditions, the novel chemosensor described here had a linear response range for Cu(II) from 1.0 × 10(-8) to 1.0 × 10(-6) mol dm(-3) with a detection limit of 1.0 × 10(-8) mol dm(-3).

Magnetic response of Cu (25 wt.%)-316 grade stainless steel processed by ball milling

Powder blend comprising Cu (25wt.%) and 316-stainless steel (75wt.%) has been subjected to ball milling upto 70h followed by isothermal annealing at the temperature range of 350–750°C for 1h to investigate the evolution of microstructure and magnetic properties. The ball milling of the powder blends after 10h has resulted in partitioning of the austenite stabilizing elements such as Ni from 316-stainless steel to elemental Cu leading to the transformation of the Bravais lattice of the Fe-rich phase from fcc (γ) to bcc (α). During further ball milling of the powder mixture upto 20h, the α-Fe has dissolved completely in Cu, leading to the formation of partial amorphous phase after 70h of milling. The amorphous phase of the alloy has been found to stable after annealing at 350°C and super paramagnetic in nature. Annealing of the alloy at higher temperatures has resulted in precipitation of nanocrystalline bcc-Fe in the Cu evolving ferromagnetic properties. Annealing at 750°C has resulted in collapse of the hysteresis loop due to the diminished exchange interaction as the result of grain coarsening of the α-Fe and Cu.

Physiological response of Cu and Cu mine tailing remediation of Paulownia fortunei (Seem) Hemsl

The physiological responses and Cu accumulation of Paulownia fortunei (Seem) Hemsl. were studied under 15.7-157 μmol L(-1) Cu treatments in liquid culture for 14 days; the impacts of Cu concentration in the seedlings were evaluated under Cu mine tailing culture with acetic acid and EDTA treatment for 60 days. Results showed that the concentrations of Chl-a, Chl-b and Carotenoids significantly increased (p < 0.05) at 15.7-78.7 μmol L(-1)Cu treatment and significantly decreased at 157 μmol L(-1) treatment after 14 days of Cu exposure. The activities of superoxide dismutase (SOD) and catalase (CAT) significantly increased as Cu levels were enhanced and the activities of both SOD and CAT under 157 μmol L(-1) Cu stress were 2.9 and 1.9 times higher than that of control, respectively. The concentrations of proline and soluble sugars in the leaves of P. fortunei significantly increased as the Cu concentrations were elevated. Cu concentrations in roots, stems and leaves of P. fortunei increased significantly as Cu levels increased and reached 1911, 101 and 93 μg g(-1) dry weights (DW) at 157 μmol L(-1) Cu treatment, respectively. The seedlings of P. fortunei cultivated in Cu tailing experienced unsuccessful growth and loss of leaves in all treatments due to poor nutrition of the Cu tailing. The dry weight of P. fortunei increased under all the treatments of acetic acid after 60 days exposure. However, dry weight significantly decreased under both levels of EDTA. The Cu concentrations increased significantly in roots and decreased in leaves when each was treated with both concentrations of acetic acid. The Cu concentrations in the roots, stems and leaves increased significantly, and the concentrations of Cu in the stems and leaves under the treatment of 2 μmol L(-1) EDTA reached 189.5 and 763.1 μg g(-1) DW, respectively. The result indicated that SOD, CAT, proline and soluble sugars played an important role in coping with the oxidative stress of copper. Acetic acid could promote growth and EDTA at the experimental levels, which could also enhance Cu absorption and translocation into the stems and leaves of P. fortune. Furthermore, acetic acid and EDTA could be rationally utilized in Cu-contaminated soil.

Involvement of oxidative stress-induced ERK/JNK activation in the Cu 2+/pyrrolidine dithiocarbamate complex-triggered mitochondria-regulated apoptosis in pancreatic β-cells

Oxidative stress was demonstrated to promote the progression of diabetes mellitus (DM). It has been suggested that copper may play a specific role in the progression and pathogenesis of DM. Pyrrolidine dithiocarbamate (PDTC), a widely apply to the medicine, was known to be capable of enhancing copper accumulation. In this study, we investigated the effect of submicromolar-concentration Cu 2+/PDTC complex on pancreatic β-cell damage and evaluated the role of oxidative stress in this effect. CuCl 2 (0.01–300 μM) did not affect the cell viability in β-cell line RIN-m5F cells. However, combination of CuCl 2 (0.5 μM) and PDTC (0.3 μM) markedly reduced RIN-m5F cell viability. Cu 2+/PDTC complex could also increase the LPO and decrease the intracellular reduced GSH levels, and display several features of apoptosis signals including: increase in sub-G1 cell population, annexin-V binding, and caspase-3 activity, mitochondrial dysfunctions, and the activation of PARP and caspase cascades, which accompanied with the marked increase the intracellular Cu 2+ levels. These apoptotic-related responses of Cu 2+/PDTC complex-induced could be effectively prevented by antioxidant N-acetylcysteine (NAC). Furthermore, Cu 2+/PDTC complex was capable of increasing the phosphorylations of ERK1/2 and JNK, and its upstream kinase MEK1/2 and MKK4, which could be reversed by NAC. Transfection with ERK2- and JNK-specific si-RNA and specific inhibitors SP600125 and PD98059 could inhibit ERK1/2 and JNK activation and attenuate MMP loss and caspase-3 activity induced by the Cu 2+/PDTC complex. Taken together, these results are the first report to demonstrate that the Cu 2+/PDTC complex triggers a mitochondria-regulated apoptosis via an oxidative stress-induced ERK/JNK activation-related pathway in pancreatic β-cells.

Quasicontinuum study the influence of misfit dislocation interactions on nanoindentation

Multiscale simulations using the quasicontinuum (QC) method with the embedded-atom method (EAM) potential are performed to examine the mechanical response of Cu–Ag bilayer film during nanoindentation tests. An attempt is made, from the viewpoint of collective interaction among misfit dislocations on the interface, to account for the strengthening and weakening mechanisms of interface on Cu–Ag bilayer film. The details of misfit dislocation nucleation, motion and collective interaction on Cu/Ag and Ag/Cu interfaces are discussed systematically, respectively. The investigation shows that the property and performance of Cu–Ag bilayer film mainly depend on the mechanical property of upper film. Both the strengthening and weakening effects are closely related to the collective interaction among misfit dislocations on the interface. Due to the pinning effect of interface on misfit dislocation, both the local interface migration and the voids can be observed at the core region of misfit dislocations. For nanoindentation on Cu/Ag bilayer film, the plastic deformation is localized chiefly in the lower Ag substrate and the void will disappear with the redistribution of misfit dislocations, which indicate that there are distinct protective and strengthening effects of the upper Cu film on the lower Ag substrate. While, for nanoindentation on Ag/Cu bilayer film, both the upper Ag film and the lower Cu substrate experience plastic deformation and the voids will not disappear, which imply that there are an obvious weakening effect of the upper Ag film on the lower Cu substrate. In addition, the multiscale simulation results are consistent with the experimental results.

Impact of the electrodeposition chemistry used for TSV filling on the microstructural and thermo-mechanical response of Cu

In this study, the role of electrodeposition chemistry on thermo-mechanical behavior of different Cu-films is examined. For this study, three different Cu electrodeposition chemistries were analyzed using Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS), Focused Ion Beam (FIB), Laser Scanning method, Electron Backscattered Diffraction, and the Nano-indentation techniques. It is found that the level of impurity in Cu-films, resulting from the used electrodeposition additives, has a significant impact on their microstructural and thermo-mechanical behavior. Cu-films having high impurity content showed residual stress levels that are three times higher than the less impure Cu-films. This implies that the use of such impure electrodeposition chemistry for the filling of TSVs will result in high residual stresses in the Cu–TSV, thus inducing higher stresses in Si, which could be a reliability concern. Therefore, the choice of the used electrodeposition chemistry for the filling of TSVs should not be limited only to the achievement of a void free Cu–TSV, as consideration ought to be given to their thermo-mechanical response.

Fluorescent gold clusters as nanosensors for copper ions in live cells

This paper reports the use of fluorescent gold nanoclusters synthesized using bovine serum albumin (Au-BSA) for the sensing of copper ions in live cells. The fluorescence of the clusters was found to be quenched by Cu(2+) enabling its detection in cells. The selectivity of the nanosensor was demonstrated in the presence of several cations excluding Hg(2+). We did not study the effect of Hg(2+) since it was reported earlier. The present study suggests that Cu(2+) induced fluorescence quenching is due to its binding to BSA rather than the fluorescence quenching by metal-metal interaction as in the case of Hg(2+). The Au-BSA showed excellent selectivity to Cu(2+) at various pH conditions. The 'turn off' of fluorescence can be retrieved by a Cu(2+) chelator glycine. Our results showed that gold clusters can be used as a 'turn off' sensor for copper and a 'turn on' sensor for glycine. Under the experimental conditions, the probe showed a response for Cu(2+) over a range of 100 μM to 5 mM with a detection limit of 50 μM. The role of Cu(2+) in the misfolding and disassembly of Prion Protein (PrP) leading to various maladies is well ascertained. The methodology we reported here seems to be useful in supplementing other techniques in predicting disease conditions involving Cu(2+).