From α-Keto Acids to Nitrile Oxides Enabled by Copper Nitrate: A Facile Access to Fused Isoxazolines

α-Keto acids were unprecedentedly employed as novel precursors of nitrile oxides on treatment with copper nitrate, which reacted with maleimides via [3+2] dipolar cycloaddition leading to pharmacologically interesting fused isoxazolines....

Wet chemical development of CuO/GO nanocomposites: its augmented antimicrobial, antioxidant, and anticancerous activity

This study employed a bottom-up technique to synthesize copper oxide (CuO) nanoparticles over hydrophilic graphene oxide (GO) nanosheets. The CuO/GO nanocomposite has been prepared using two selected precursors of copper nitrate and citric acid with an intermittent mixing of GO solutions. The synthesized Nanocomposites were characterized using different biophysical techniques like FT-IR, NMR, FE-SEM, and HR-TEM analyses. FT-IR analyses confirm the nanocomposites’ successful formation, which is evident from the functional groups of C=C, C-O, and Cu-C stretching vibrations. Morphological analyses reveal the depositions of CuO nanoparticles over the planar rough GO sheets, which has been elucidated from the FE-SEM and HR-TEM analyses supported by respective EDAX analyses. The antimicrobial activities have been evident from the surface roughness and damages seen from the FE-SEM analyses. The CuO/GO sheets were tested against Gram-positive (e.g., Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa). It is evident that the intrinsic antibacterial activity of CuO/GO sheets, when combined in equal proportions, elicited a robust antibacterial activity when tested over Gram –ve representative bacteria Escherichia coli. The antioxidant behaviour of synthesized CuO/GO nanocomposite was evaluated by scavenging the free radicals of DPPH and ABTS. Moreover, the cytotoxic activity was also studied against epidermoid carcinoma cell line A-431. A brief mathematical formulation has been proposed in this study to uncover the possibilities of using the nanocomposites as potential drug candidates in theranostic applications in disease treatment and diagnosis. This study would help uncover the electronic properties that play in the nano-scaled system at the material-bio interface, which would aid in designing a sensitive nano-electromechanical device bearing both the therapeutic and diagnostic attributes heralding a new horizon in the health care systems.

Study of the Effect of Nitrate and Sulfate Solutions on the Properties of Copper Nanopowder Synthesized by Electrochemical Method

The electrochemical method is efficient, cost effective, and environmentally friendly process. Copper nanopowder has been known, as a nontoxic, inexpensive, highly conductive, excellent microbial agent, catalytic, and sensors applicable. Copper nanopowder was prepared by an electrochemical method under various conditions. The effect of type and concentration of electrolyte solution, and the sample treated with thiourea and ascorbic acid on the size and purity of copper nanopowder was investigated. Two different salts copper: sulfate and nitrate aqueous solutions (CuSO4.5H2O), Cu(NO3)2.5H2O were used to produce copper nanopowder. The synthesized copper nanopowder was identified using X-ray diffraction (XRD), the scanning electron microscope (SEM), and Energy Dispersive Spectrum (EDS). The results of XRD patterns revealed a high degree of crystallinity, monophasic nature, and pure copper powder with no impurities or oxides observed for both electrolyte solutions after treated with 2 percent of ascorbic acid. It was confirmed that particle size at room temperature was as small as 25nm when the copper nitrate is used as an electrolyte solution compared to copper sulfate (41nm).

Effect of Ca2+ Replacement with Cu2+ Ions in Brushite on the Phase Composition and Crystal Structure

The gradual replacement of Ca2+ with Cu2+ ions in brushite (CaHPO4·2H2O) has been extensively studied and discussed. The approach adopted in this work has not been systematically explored in previous studies. This novel approach may prove beneficial for the production of Ca1−xCuxHPO4·nH2O materials with desired properties suitable for medical applications. Solutions of sodium dihydrogen orthophosphate dihydrate, NaH2PO4·2H2O, calcium nitrate tetrahydrate, Ca(NO3)2·4H2O, copper nitrate trihydrate, Cu(NO3)2·3H2O, ammonium hydroxide solution, and diluted HCl were used for the preparation of these materials. At low Cu/Ca molar ratios (up to 0.25) in the starting solution, biphasic phosphate minerals were formed: brushite and sampleite. When the Cu/Ca molar ratio increases gradually from 0.67 to 1.5, sampleite-like mineral precipitates. Powdered XRD (X-ray diffraction), thermogravimetric (TG) analysis, and SEM (scanning electron microscopy) techniques were employed for the study of the microstructure of the produced materials for different degrees of Ca replacement with Mg. It is found that the Cu/Ca ratio in the starting solution can be adjusted to obtain materials with tailored composition. Thus, a new method of sampleite-like synthesis as a rare mineral is introduced in this study. Both phosphate minerals brushite and sampleite-like minerals are attractive as precursors of bioceramics and biocements. The search for such products that may decrease the possibility of post prosthetic or implant infection can be crucial in preventing devastating post-surgical complications.

Development of a Nanocluster-Based Platform for Determination of Sofosbuvir

Background: Sofosbuvir is a potent direct-acting antivirus agent that has been listed as a promising medicine for the treatment of all genotypes of hepatitis C virus. As antiviral drugs could be metabolized to their associated compounds and toxicologically and pharmacologically interfere with the parent drugs, identifying the therapeutic range of drugs would be notable. Methods: In the current study, copper nanoclusters (Cu NCs) are synthesized during the reduction of copper nitrate with hydrazine hydrate in a protected media and used as a nanoprobe for the determination of sofosbuvir in plasma samples. Herein, synchronous fluorescence spectroscopy (SFS) is used for monitoring of fluorescence variation of nanoprobe owing to the excessive benefits compared with the traditional fluorescence. Results: SFS peak of Cu NCs has appeared at 355 nm with ∆λ=80 nm which is decreased in the presence of sofosbuvir. To optimize the reaction factors, a response surface methodology is used and in the optimized conditions, a linear concentration-response plot is obtained in a range of 0.05-6.0 µg mL−1 with a limit of detection of 0.0147 µg mL−1. Conclusion: The developed method also reveals good repeatability and selectivity for sofosbuvir in plasma samples.

M(II)Al4 Type Layered Double Hydroxides—Preparation Using Mechanochemical Route, Structural Characterization and Catalytic Application

The synthesis of the copper-poor and aluminum-rich layered double hydroxides (LDHs) of the CuAl4 type was optimized in detail in this work, by applying an intense mechanochemical treatment to activate the gibbsite starting reagent. The phase-pure forms of these LDHs were prepared for the first time; using copper nitrate and perchlorate salts during the syntheses turned out to be the key to avoiding the formation of copper hydroxide sideproducts. Based on the use of the optimized syntheses parameters, the preparation of layered triple and multiple hydroxides was also attempted using Ni(II), Co(II), Zn(II) and even Mg(II) ions. These studies let us identify the relative positions of the incorporating cations in the well-known selectivity series as Ni2+ >> Cu2+ >> Zn2+ > Co2+ >> Mg2+. The solids formed were characterized by using powder X-ray diffractometry, UV–Vis diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. The catalytic potential of the samples was investigated in carbon monoxide oxidation reactions at atmospheric pressure, supported by an in situ diffuse reflectance infrared spectroscopy probe. All solids proved to be active and the combination of the nickel and cobalt incorporation (which resulted in a NiCoAl8 layered triple hydroxide) brought outstanding benefits regarding low-temperature oxidation and increased carbon monoxide conversion values.

Microstructural and Corrosion Properties of Burnished 6060 Aluminum Alloy

A process for producing a black oxide coating on aluminum alloy was investigated in the present work. The blackening process is widely used in industrial applications, but it was not deeply studied for aluminum alloys. The aim of this work is to study the black coating obtained on AA6060 surfaces employing two different solutions, both containing potassium permanganate, copper nitrate and nitric acid. The first solution carried out the coloring treatment at 50 °C, whereas the second one was done at room temperature. Different immersion times were investigated. The morphology of the coating was investigated by means of optical and electron microscopy to evaluate the color of the layer and the presence of defects, porosities, and cracks. X-ray diffraction analysis was performed to evaluate the protective layer composition. The corrosion properties were studied with potentiodynamic polarization tests and electrochemical impedance spectroscopy tests. The results showed that the blackening process performed at room temperature, besides the clear advantages in term of costs and safety, obtained more uniform coatings with increased corrosion performance in comparison with the ones obtained at higher temperatures.