Cupric Ions (cupric + ion)

Distribution by Scientific Domains


Selected Abstracts


Improved Voltammetric Response of L -Tyrosine on Multiwalled Carbon Nanotubes-Ionic Liquid Composite Coated Glassy Electrodes in the Presence of Cupric Ion

ELECTROANALYSIS, Issue 19 2008
Liqin Liu
Abstract L -Tyrosine can exhibit a small anodic peak on multiwalled carbon nanotubes (MWCNTs) coated glassy carbon electrodes (GCE). At pH,5.5 its peak potential is 0.70,V (vs. SCE). When an ionic liquid (i.e., 1-octyl-3-methylimidazolium hexafluorophosphate, [omim][PF6]) is introduced on the MWCNT coat, the peak becomes bigger. Furthermore, in the presence of Cu2+ ion the anodic peak of L -tyrosine increases further due to the formation of Cu2+ - L -tyrosine complex, while the peak potential keeps unchanged. Therefore, a sensitive voltammetry based on the oxidation of Cu2+ - L -tyrosine complex on MWCNTs-[omim][PF6] composite coated electrode is developed for L -tyrosine. Under the optimized conditions, the anodic peak current is linear to L -tyrosine concentration in the range of 1×10,8,5×10,6 M, and the detection limit is 8×10,9 M. The modified electrode shows good reproducibility and stability. In addition, the voltammetric behavior of other amino acids is explored. It is found that among them tryptophan (Trp) and histidine (His) can also produce sensitive anodic peak under same experimental conditions, and their detection limits are 4×10,9 M and 4×10,6 M, respectively. [source]


Cupric ion enhanced molecular imprinting of bovine serum albumin in hydrogel

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 19 2009
Sheng-Hua Li
Abstract A novel molecularly imprinted hydrogel for bovine serum albumin (BSA) was prepared using cupric ion as the bridge between the template BSA and the functional monomer 4-vinylpyridine. N-Isopropylacrylamide (NIPA) was used as an assistant monomer to provide the stimuli-responsibility of the polymer. The adsorption conditions of BSA on the BSA-Cu(II)-imprinted hydrogel were optimized considering the influences of pH, temperature, and salt concentration. The proteins bound on the imprinted hydrogel can be easily recovered under mild conditions by using 10 mmol/L ethylene diamine tetraacetic acid (EDTA) (pH 7.0) containing 150 mmol/L NaCl as the eluting solution. The imprinting effect and adsorption capacity of the polymer were found to be significantly improved compared to the hydrogel prepared in the absence of cupric ion. The results demonstrated the advantages of using a template-metal ion-monomer coordination system to strengthen the interaction between the protein and monomer. The effects of different metals ions including Zn(II), Ni(II), Co(II), Cd(II), and Al(III) on the recognition ability of the BSA-Cu(II)-imprinted hydrogel were also investigated. The polymer showed high selectivity toward both the template protein and the cupric ion. [source]


Long-lasting contractile action and the inhibitory action of cupric ions on ileal longitudinal muscle

AUTONOMIC & AUTACOID PHARMACOLOGY, Issue 4 2004
K. Miyazaki
Summary 1 Cupric ions (Cu2+), at concentrations above 0.03 mm, induced a progressive increase in the tonic contraction of guinea-pig ileal longitudinal muscle. Maximal contraction of 0.1 mm Cu2+ attained a level above that of the 60-mm K+ -induced tonic response, within 20 min of application. The tension induced by Cu2+ persisted for more than several hours. Tetrodotoxin (3 × 10,6 m) had no effect on the contraction induced by 0.1 mm Cu2+. 2 After incubation in a Ca2+ -free medium, the ileal response to 0.1 mm Cu2+ was lost. Nifedipine, a L-type Ca2+ channel blocker, dose-dependently inhibited contractions induced by Cu2+. 3 As the duration of the first application of 0.1 mm Cu2+ increased above 30 min, after washing with normal medium, the contractile response to a second application of 0.1 mm Cu2+ decreased gradually. After 150 min of the first application of 0.1 mm Cu2+, a second application of Cu2+ could not evoke any contraction. 4 After the application of 0.1 mm Cu2+ for 150 min, when muscles were washed with a medium containing 1 mm EDTA, the response to 0.1 mm Cu2+ returned to a greater extent in the normal Ca2+ medium. 5 In conclusion, Cu2+ (0.1 mm) induced a maximal ileal tension above that of the K-induced tonic response within 20 min. The ileal contraction to Cu2+ persisted for more than several hours and depended on extracellular Ca2+ concentrations. It is possible that a part of Cu2+, bound to a EDTA-inaccessible site, also has a tension inhibitory effect. [source]


The effects of copper on the microbial community of a coral reef sponge

ENVIRONMENTAL MICROBIOLOGY, Issue 1 2001
Nicole S. Webster
Marine sponges often harbour communities of symbiotic microorganisms that fulfil necessary functions for the well-being of their hosts. Microbial communities associated with the sponge Rhopaloeides odorabile were used as bioindicators for sublethal cupric ion (Cu2+) stress. A combined strategy incorporating molecular, cultivation and electron microscopy techniques was adopted to monitor changes in microbial diversity. The total density of sponge-associated bacteria and counts of the predominant cultivated symbiont (,-proteobacterium strain NW001) were significantly reduced in response to Cu2+ concentrations of 1.7 µg l,1 and above after 14 days of exposure. The number of operational taxonomic units (OTUs) detected by restriction fragment length polymorphism (RFLP) decreased by 64% in sponges exposed to 223 µg l,1 Cu2+ for 48 h and by 46% in sponges exposed to 19.4 µg l,1 Cu2+ for 14 days. Electron microscopy was used to identify 17 predominant bacterial morphotypes, composing 47% of the total observed cells in control sponges. A reduction in the proportion of these morphotypes to 25% of observed cells was evident in sponges exposed to a Cu2+ concentration of 19.4 µg l,1. Although the abundance of most morphotypes decreased under Cu2+ stress, three morphotypes were not reduced in numbers and a single morphotype actually increased in abundance. Bacterial numbers, as detected using fluorescence in situ hybridization (FISH), decreased significantly after 48 h exposure to 19.4 µg l,1 Cu2+. Archaea, which are normally prolific in R. odorabile, were not detected after exposure to a Cu2+ concentration of 19.4 µg l,1 for 14 days, indicating that many of the microorganisms associated with R. odorabile are sensitive to free copper. Sponges exposed to a Cu2+ concentration of 223 µg l,1 became highly necrosed after 48 h and accumulated 142 ± 18 mg kg,1 copper, whereas sponges exposed to 19.4 µg l,1 Cu2+ accumulated 306 ± 15 mg kg,1 copper after 14 days without apoptosis or mortality. Not only do sponges have potential for monitoring elevated concentrations of heavy metals but also examining changes in their microbial symbionts is a novel and sensitive bioindicator for the assessment of pollution on important microbial communities. [source]


Cupric ion enhanced molecular imprinting of bovine serum albumin in hydrogel

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 19 2009
Sheng-Hua Li
Abstract A novel molecularly imprinted hydrogel for bovine serum albumin (BSA) was prepared using cupric ion as the bridge between the template BSA and the functional monomer 4-vinylpyridine. N-Isopropylacrylamide (NIPA) was used as an assistant monomer to provide the stimuli-responsibility of the polymer. The adsorption conditions of BSA on the BSA-Cu(II)-imprinted hydrogel were optimized considering the influences of pH, temperature, and salt concentration. The proteins bound on the imprinted hydrogel can be easily recovered under mild conditions by using 10 mmol/L ethylene diamine tetraacetic acid (EDTA) (pH 7.0) containing 150 mmol/L NaCl as the eluting solution. The imprinting effect and adsorption capacity of the polymer were found to be significantly improved compared to the hydrogel prepared in the absence of cupric ion. The results demonstrated the advantages of using a template-metal ion-monomer coordination system to strengthen the interaction between the protein and monomer. The effects of different metals ions including Zn(II), Ni(II), Co(II), Cd(II), and Al(III) on the recognition ability of the BSA-Cu(II)-imprinted hydrogel were also investigated. The polymer showed high selectivity toward both the template protein and the cupric ion. [source]


Structural Evolution and Copper-Ion Release Behavior of Cu-pHEMA Hybrids Synthesized In Situ,

ADVANCED ENGINEERING MATERIALS, Issue 11 2009
Yen-Yu Liu
Abstract A novel Cu-pHEMA hybrid was successfully prepared by in situ photopolymerization of 2-hydroxyethyl methacrylate (HEMA) monomer in the presence of Cu(II) copper ions, following an in situ chemical reduction. Experimental observations indicate that intermolecular interactions such as the coupling force and hydrogen bonding between the Cu and the hydroxyl groups further stabilize the hybrid structure to a considerable extent. Localization of the metallic copper particles within the pHEMA network structure as a result of those intermolecular interactions gives rise to the formation of discretely distributed nanocrystallites with particle sizes ranging from 5 to 25,nm in diameter. A crystallographic change of the Cu nanophase from an amorphous-like to a crystalline structure is observed as the H2O:HEMA molar ratio increases, upon synthesis, accompanied with an increase in the particle size. A relatively slow and sustained release of the Cu (in the form of cupric ions) from the hybrids was measured for a time period of about 10 days, which also illustrates a Cu(II)-induced proliferation of the endothelial cells over a relatively small range of release rate of the Cu from the hybrids. Such a new type of Cu-loaded hybrid hydrogel is expected to be compatible and may be considered as a candidate biomaterial for biomedical/therapeutic uses. [source]


Removal of cupric ions from acidic sulfate solution using reticulated vitreous carbon rotating cylinder electrodes

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2004
Gavin W Reade
Abstract The potentiostatic deposition of copper from acid sulfate solutions (0.50 mol dm,3 Na2SO4 at pH 2 and 298 K) was studied at four porosity grades (10, 30, 60 and 100 pores per linear inch, ppi) of reticulated vitreous carbon (RVC) rotating cylinder electrode (RCE). The rate of removal of cupric ions from a 200 cm3 volume of electrolyte was examined as a function of the grade of RVC foam, the electrode potential and the initial cupric ion concentration. For the 100 ppi material, the product of the mass transport coefficient and the electroactive area per unit volume of electrode (kmAe) was equal to 0.28 s,1 at a potential of ,500 mV vs SCE for an initial cupric ion concentration of 0.85 mmol dm,3 and a constant rotation speed of 1500 rev min,1. Under the experimental conditions, an initial dissolved copper concentration of 63.5 ppm could be reduced to <0.1 ppm in approximately 60 min using a 100 ppi RVC RCE. SEM studies showed some non-uniform deposition of metal due to heterogeneous nucleation of copper together with the development of rough deposits. Copyright © 2004 Society of Chemical Industry [source]


Investigation of a CuII,Poly(, -Glutamic Acid) Complex in Aqueous Solution and its Insulin-Mimetic Activity

MACROMOLECULAR BIOSCIENCE, Issue 4 2007
Subarna Karmaker
Abstract The complexation between cupric ions (CuII) and poly(, -glutamic acid) (, -PGA) in aqueous solutions (pH 3,11) has been studied by UV-visible absorption and electron spin resonance (ESR) techniques. Formation of the CuII - , -PGA complex is confirmed by the observation of the blue shift of the absorption band in the visible region, anisotropic line shapes in the ESR spectrum at room temperature, and a computer simulation of the visible absorption spectrum of the complex. The structure of the CuII - , -PGA complex, depending on the pH, has been determined. The in vitro insulin-mimetic activity of the CuII - , -PGA complex is examined by determining both inhibition of free fatty acid release and glucose uptake in isolated rat adipocytes treated with epinephrine, in which the concentration of the CuII - , -PGA complex for 50% inhibition of free fatty acid release is very similar to that of CuSO4. However, it is significantly lower than that of a previously reported insulin-mimetic bis(3-hydroxypicolinato)copper(II), [Cu(3hpic)2], complex. [source]


Cholinergic responses of ileal longitudinal muscle under short-lasting exposure to cupric ions

AUTONOMIC & AUTACOID PHARMACOLOGY, Issue 1 2008
Ch. Nachev
Summary 1 The effect of short-term exposure to cupric ions (Cu2+) on electric field-stimulated (EFS) or agonist-induced contractions of guinea-pig isolated ileum was studied. 2 EFS elicited tetrodotoxin- and atropine-sensitive contractions that were concentration dependently inhibited by Cu2+ (IC50 = 14.7 ± 4.2 ,m). Maximal inhibition (90.4 ± 3.1% of baseline contractions) was attained with 30 ,m Cu2+. 3 Carbachol induced concentration-dependent contractions (EC50 = 0.021 ± 0.004 ,m) that were inhibited by 0.3 ,m atropine to a non-competitive manner (decreased maximal response, EC50 value = 0.26 ± 0.04 ,m, Ke = 0.026 ,m). Cu2+ (15 ,m) potentiated contractions induced by carbachol, such that the maximum response was increased by 30.3 ± 10.4%. 4 Histamine induced concentration-dependent contractions of the longitudinal muscle (EC50 = 0.11 ± 0.03 ,m). Dyphenhydramine (0.1 ,m) decreased the maximum response to histamine and shifted the curve to the right (EC50 value = 4.71 ± 0.35 ,m, Ke = 0.0024 ,m). Cu2+ (15 ,m) caused a rightward shift of the histamine concentration,response curve (EC50 = 0.61 ± 0.1 ,m) without changing the maximum response. Serotonin induced concentration-dependent contractions at concentrations higher than 10 nM (EC50 value of 0.34 ± 0.12 ,m) were not significantly affected by 15 ,m Cu2+. 5 Our results suggest that in ileal longitudinal muscle, Cu2+ inhibits cholinergic neurotransmission but also facilitates postsynaptic muscarinic receptor responses. [source]


Long-lasting contractile action and the inhibitory action of cupric ions on ileal longitudinal muscle

AUTONOMIC & AUTACOID PHARMACOLOGY, Issue 4 2004
K. Miyazaki
Summary 1 Cupric ions (Cu2+), at concentrations above 0.03 mm, induced a progressive increase in the tonic contraction of guinea-pig ileal longitudinal muscle. Maximal contraction of 0.1 mm Cu2+ attained a level above that of the 60-mm K+ -induced tonic response, within 20 min of application. The tension induced by Cu2+ persisted for more than several hours. Tetrodotoxin (3 × 10,6 m) had no effect on the contraction induced by 0.1 mm Cu2+. 2 After incubation in a Ca2+ -free medium, the ileal response to 0.1 mm Cu2+ was lost. Nifedipine, a L-type Ca2+ channel blocker, dose-dependently inhibited contractions induced by Cu2+. 3 As the duration of the first application of 0.1 mm Cu2+ increased above 30 min, after washing with normal medium, the contractile response to a second application of 0.1 mm Cu2+ decreased gradually. After 150 min of the first application of 0.1 mm Cu2+, a second application of Cu2+ could not evoke any contraction. 4 After the application of 0.1 mm Cu2+ for 150 min, when muscles were washed with a medium containing 1 mm EDTA, the response to 0.1 mm Cu2+ returned to a greater extent in the normal Ca2+ medium. 5 In conclusion, Cu2+ (0.1 mm) induced a maximal ileal tension above that of the K-induced tonic response within 20 min. The ileal contraction to Cu2+ persisted for more than several hours and depended on extracellular Ca2+ concentrations. It is possible that a part of Cu2+, bound to a EDTA-inaccessible site, also has a tension inhibitory effect. [source]


A Cascade FRET-Mediated Ratiometric Sensor for Cu2+Ions Based on Dual Fluorescent Ligand-Coated Polymer Nanoparticles

CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2009
Michel Frigoli Dr.
Abstract Core-shell type dual fluorescent nanoparticles (NPs) in the 16,nm diameter range with a selective ligand (cyclam) attached to the surface and two fluorophores,9,10-diphenyl-anthracene (donor, D) and pyrromethene PM,567 (acceptor, A),embedded within the polymer core were synthesized and their fluorescent and copper-sensing properties were studied and compared to single D -doped and A -doped NPs. The acceptor (A) and donor (D) dyes were chosen to allow two sequential Förster resonance energy transfer (FRET) processes from D to A and from the encapsulated dyes to copper complexes that form at the surface and act as quenchers. NPs with different D/A loads were readily obtained by two consecutive entrapments of the dyes. Dual NPs present tunable fluorescence emission that is dependent on the doping ratio. FRET from D to A results in sensitized emission from A upon excitation of D, with FRET efficiencies reaching 80,% at high acceptor loads. A 9-fold amplification of the signal of A is observed at high D -to- A ratios. Single- and dual-dye-doped NPs were used to detect the presence of cupric ions in water by using the quenching of fluorescence as a transduction signal. In accordance with the spectral overlaps and the values of the critical distance (R0) of D, and A,copper complex pairs, the acceptor is much more sensitive than the donor. In dual fluorescent NPs, the sensitized emission of A is efficiently attenuated whereas the remaining emission of D is much less affected, allowing the detection of copper in a ratiometric manner upon excitation at a single (D) wavelength. Dual-dye-doped NPs with the highest acceptor loads (23,A -per-NP) were found to be the most sensitive for the detection of copper over a wide range of concentrations (20,nM to 8.5,,M). Owing to its great convenience and modularity, the cascade FRET strategy based on dual fluorescent NPs holds great promise for the design of various sensing nanodevices. [source]