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Abstract Background The amyloid β-peptide is a ubiquitous peptide, which is prone to aggregate forming soluble toxic oligomers and insoluble less-toxic aggregates. The intrinsic and external/environmental factors that determine Aβ aggregation in vivo are poorly understood, as well as the cellular meaning of this process itself. Genetic data as well as cell biological and biochemical evidence strongly support the hypothesis that Aβ is a major player in the onset and development of Alzheimer's disease. In addition, it is also known that Aβ is involved in Inclusion Body Myositis, a common myopathy of the elderly in which the peptide accumulates intracellularly. Results In the present work, we found that intracellular Aβ aggregation in muscle cells of Caenorhabditis elegans overexpressing Aβ peptide is affected by two single amino acid substitutions, E22G (Arctic) and V18A (NIC). Both variations show decrease intracellular amyloidogenesis compared to wild type Aβ. We show that intracellular amyloid aggregation of wild type Aβ is accelerated by Cu2+ and diminished by copper chelators. Moreover, we demonstrate through toxicity and behavioral assays that Aβ-transgenic worms display a higher tolerance to Cu2+ toxic effects and that this resistance may be linked to the formation of amyloid aggregates. Conclusion Our data show that intracellular Aβ amyloid aggregates may trap excess of free Cu2+ buffering its cytotoxic effects and that accelerated intracellular Aβ aggregation may be part of a cell protective mechanism.

The interaction of the ethyl xanthate (EX) anion with a copper electrode in a borate buffer solution, pH 9.2, is investigated by cyclic voltammetry (CV), electrochemical quartz crystal microbalance (EQCM), electrochemical impedance spectroscopy (EIS), and measurements of contact angle (CA) under controlled potential. The EQCM study shows that in the electrodesorption process the departure of each ethyl xanthate species from the copper electrode is accompanied with the simultaneous entry of four to five water molecules.

Electrodic surfaces of natural chalcopyrite and natural pyrite minerals are studied by cyclic voltammetry, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy including microanalysis. At high oxidation states, both minerals showed a pseudoinductive loop in the equivalent circuit, which was due to the active electrodissolution of the minerals, which takes place through a surface film previously formed.

An electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry (CV) in an alkaline solution (0-5 M Na2B4O7) containing selonie ion were used to study the electroformation of Cu-Ce phases. The results and atomic force microscopy (AFM) experiences supported that the growth of the Cu-Se films occurs through a layer-by layer mechanism.

Thin films of copper(I) oxide (Cu2O) were electrodeposited on fluorine-doped tin oxide predeposited glass substrates, by reduction of Cu2+ from Cu(II) acetate acid aqueous solutions. The Cu2O was potentiostatically grown at a potential value of −0.450 V (vs. SMSE) at 70 °C. The Cu2O thin films were characterized by means of scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), optical transmission, electrochemical impedance spectroscopy, and photoelectrochemical experiments. Through these techniques, it was possible to establish the cubic Cu2O phase with a high crystallinity and a strong preferential growth along the [200] and [220] directions. Cu2O thin films show oxygen vacancies with formation of a nonstoichiometric compound with the presence of Cu(0) in the crystal lattice as determined by XPS analysis. In addition, Cu2O was used as the photoanode for the I− oxidation reaction when the system was illuminated ( Φ0 = 50.0 mW cm−2). The films exhibited a clear n-type semiconductor behavior, which was in agreement with the Mott-Schottky results. This behavior was explained by considering the nonstoichiometry of the oxide. [ABSTRACT FROM AUTHOR]

Photoelectrochemical response of electrodeposited hematite (-Fe2O3) thin films, whose surface has been modified by a catalytic cobalt layer, has been studied. Structural and morphological characteristics of the resulting nanostructured hematite films have been studied by X-ray diffraction and scanning electron microscopy techniques. Surface characterization of the Co-modified hematite films has been carried out by X-ray photoelectron spectroscopy in order to study the chemical nature of Co onto these films. The hematite films exhibited an n-type behavior, and a donor carrier concentration, ND = 3 × 1017 and 1018 cm-3 for the un-modified and Co-modified ones, respectively. The photoelectrochemical performance of the un-modified and Co-modified electrochemically grown hematite thin films has been explored using a liquid-junction in a photoelectrochemical system in a 0.1 M NaOH electrolytic solution, under monochromatic illumination of wavelengths over the range 350-600 nm. Significant performance gaining can be seen upon Co-modification throughout the illumination wavelengths. Cobalt modification enhances the IPCE by a factor of 1.1-2.0 (370-450 nm range), and by a factor of 2.0 (at 350 nm). With an IPCE of 46% at 370 nm at 1.43 V vs. RHE, this electrode is much more efficient in water photo-oxidation than the best published Fe2O3 single-crystal specimen. [ABSTRACT FROM AUTHOR]

The photoelectrochemical response of electrodeposited hematite (α-Fe2O3) thin films, whose surface has been sensitized by the adsorption of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP). was studied. The α-Fe2O3 thin films were obtained by the annealing of an electrodeposited β-FeOOH precursor layer. The structural and morphological characteristics of the resulting hematite films were studied by X-ray diffraction, scanning electron microscopy, and atomic force microscopy techniques. The semiconducting characteristics of unmodified and sensitized TCPP hematite films were determined by electrochemical impedance measurements and by Mott-Schottky analysis. The hematite films exhibited an n-type behavior and a donor carrier concentration (ND = 3 x 1017 cm3) for both unmodified and TCPP-sensitized ones. However, it was observed that the presence of TCPP shifts the energy of the surface states to higher values. The photoelectrochemical response of the unmodified and sensitized α-Fe2O3 electrodes was followed by means of photovoltammetry and photocurrent-time transient techniques in a 0.1 M NaOH + 0.1 M KI solution under 25 mW/cm2 white light illumination. The results showed that the photocurrent response exhibited by the TCPP-sensitized hematite films was 70% higher than the unmodified ones. [ABSTRACT FROM AUTHOR]