Bacterial synthesis of copper/copper oxide nanoparticles

A bacterial mediated synthesis of copper/copper oxide nanoparticle composite is reported. A Gram-negative bacterium belonging to the genus Serratia was isolated from the midgut of Stibara sp., an insect of the Cerambycidae family of beetles found in the Northwestern Ghats of India. This is a unique bacterium that is quite specific for the synthesis of copper oxide nanoparticles as several other strains isolated from the same insect and common Indian mosquitoes did not result in nanoparticle formation. By following the reaction systematically, we could delineate that the nanoparticle formation occurs intracellularly. However, the process results in the killing of bacterial cells. Subsequently the nanoparticles leak out as the cell wall disintegrates. The nanoparticles formed are thoroughly characterized by UV-Vis, TEM, XRD, XPS and FTIR studies.     

Synthesis of copper and copper(I) oxide nanoparticles by thermal decomposition of a new precursor

The present investigation reports, the novel synthesis of nanoparticles Cu and Cu₂O using thermal decomposition and its physicochemical characterization. The nanoparticles copper powder have been prepared using [Bis(salicylidiminato)copper(II)], [Cu(sal)₂], as precursor. Cu nanoparticles are initially formed and subsequently oxidized to form Cu₂O. Transmission electron microscopy (TEM) analysis demonstrated nanoparticles Cu₂O with an average diameter of about 10 nm. As-prepared copper nano-particles were characterized by X-ray diffraction measurements (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), and Fourier transform infra-red spectroscopy (FTIR). XRD analysis revealed broad pattern for fcc crystal structure of copper metal and cubic cuprite structure for Cu₂O. Optical absorption measured by UV–visible spectroscopy was used to monitor oxidation course of Cu → Cu₂O and to determine the band-gap energy about 2.4 eV for Cu₂O nanoshells.     

Temperature dependent rheological property of copper oxide nanoparticles suspension (nanofluid)

A nanofluid is the dispersion of metallic solid particles of nanometer size in a base fluid such as water or ethylene glycol. The presence of these nanoparticles affects the physical properties of a nanofluid via various factors including shear stress, particle loading, and temperature. In this paper the rheological behavior of copper oxide (CuO) nanoparticles of 29 nm average diameter dispersed in deionized (DI) water is investigated over a range of volumetric solids concentrations of 5 to 15% and various temperatures varying from 278-323 degrees K. These experiments showed that these nanofluids exhibited time-independent pseudoplastic and shear-thinning behavior. The suspension viscosities of nanofluids decrease exponentially with respect to the shear rate. Suspension viscosity follows the correlation in the form ln(mus) = A(1/T)-B, where constants A and B are the functions of volumetric concentrations. The calculated viscosities from the developed correlations and experimental values were found to be within +/- 10% of their values.     

Zinc oxide nanoparticles: A study of defect level blue-green emission

Systematic investigation of the structural, morphological and optical properties of hexylamine capped zinc oxide (ZnO) nanoparticles is presented. Optical properties indicate the presence of sufficient amount of surface defects. These defects in highly dispersed ZnO nanoparticles have been studied by annealing the nanoparticles in air at various temperatures and recording the photoluminescence spectra. The annealing temperature was found to strongly influence the UV band edge emission and the blue-green defect level emission (DLE). At low annealing temperatures an increase in UV emission with temperatures is observed and this emission is proposed to be a result of desorption of surface adsorbed water and hydroxyl groups. The DLE of the synthesized sample is likely due to the presence of oxygen vacancies on the surface resulting in green emission.     

Tight-binding molecular-dynamics study of a copper oxide Cu4O

The empirical tight-binding molecular dynamic simulations of Cu₄O are performed. It is shown that the atomic and electronic structure can be calculated reasonably with this kind of TB model and repulsive potentials used in this paper. The calculated structures are in good agreement with the results obtained by atomic resolution electron microscope.     

Potentiating effect of ecofriendly synthesis of copper oxide nanoparticles using brown alga: antimicrobial and anticancer activities

This study reports the in vitro antimicrobial and anticancer activities of biologically synthesized copper nanoparticles. The antimicrobial activity of green synthesized copper oxide nanoparticles was assessed by well diffusion method. The anticancer activity of brown algae-mediated copper oxide nanoparticles was determined by MTT assay against the cell line (MCF-7). Maximum activity was observed with Pseudomonas aeruginosa and Aspergillus niger. Effective growth inhibition of cells was observed to be more than 93% in antibacterial activity. Thus, the results of the present study indicates that biologically synthesized copper nanoparticles can be used for several diseases, however, it necessitates clinical studies to ascertain their potential as antimicrobial and anticancer agents.     

Copper/copper oxide nanoparticles synthesis using Stachys lavandulifolia and its antibacterial activity

Nanoparticles of copper/cuprous oxide (Cu/Cu₂ O) were successfully synthesised by a green chemistry route. The synthesis process was carried out using an extract of Stachys lavandulifolia as both reducing and capping agents with a facile procedure. The nanoparticles were characterised by different techniques including X‐ray diffraction, indicating that the synthesised sample comprised both copper and cuprous oxide entity. The nanoparticles had a mean size of 80 nm and represented an impressive bactericidal effect on Pseudomonas aeruginosa.Inspec keywords: copper, copper compounds, nanoparticles, nanofabrication, nanomedicine, antibacterial activity, X‐ray diffractionOther keywords: nanoparticles synthesis, Stachys lavandulifolia, antibacterial activity, green chemistry route, reducing agents, capping agents, X‐ray diffraction, bactericidal effect, Pseudomonas aeruginosa, Cu‐Cu₂ O     

Antibacterial magnetic nanoparticles for therapeutics: a review

Along with the extensive range of exotic nanoparticle (NPs) applications, investigation of magnetic NPs (MNPs) in vitro has ushered modern antibacterial studies into an increasingly attractive research area. A great number of microorganisms exist in the size scales from nanometre to micrometre regions. The enormous potential of engineered MNPs in therapeutic procedures against various drug‐resistant bacteria has declined the menace of fatal bacterial infections. Many biocompatible MNPs have been introduced that possess remarkable impacts on various bacterial strains. Conventional synthesis methods such as co‐precipitation or hydrothermal techniques have been widely adopted in the production of MNPs. The MNPs for antibacterial applications are mainly required to be superparamagnetic, recyclable and biocompatible. To implement novel strategies in developing new generation antimicrobial magnetic nanomaterials, it is essential to obtain a comprehensive preview of recent achievements in synthesis, proposed antibacterial mechanisms and characterisation techniques of these nanomaterials. This review highlights notable aspects of antibacterial activity in engineered MNPs and nanocomposites including their particle properties (size, shape and saturation magnetisation), antibacterial mechanisms, synthesis methods, testing methods, surface modifications and minimum inhibitory concentrations.Inspec keywords: nanocomposites, magnetic particles, biomedical materials, antibacterial activity, nanofabrication, nanoparticles, drugs, precipitation (physical chemistry), reviews, nanomagnetics, superparamagnetism, nanomedicineOther keywords: drug‐resistant bacteria, fatal bacterial infections, bacterial strains, conventional synthesis methods, antibacterial applications, antibacterial activity, exotic nanoparticle applications, antibacterial mechanisms, antimicrobial magnetic nanomaterials, antibacterial MNP, biocompatible MNP, in vivo magnetic nanoparticle, review, hydrothermal techniques, superparamagnetism, nanocomposites, surface modifications     

Copper oxide nanowires: a review of growth

Cuprous oxide (Cu(2)O) and cupric oxide (CuO) nanowires have started playing important roles in energy conversion devices and optoelectronic devices. Although the desired advanced properties have been demonstrated, these materials cannot yet be produced in large-bulk quantities in order to bridge the technological transfer gap for wider use. In this respect, the quest for the most efficient synthesis process which yields not only large quantities but also high quality and advanced material properties continues. This paper gives an extensive review of copper oxide nanowire (NW) synthesis by all methods and routes by which various researchers have obtained their nanomaterial. These methods are critically overviewed, evaluated and compared. Methods of copper oxide NW growth include wet-chemical methods based on pure solution growth, electrochemical and hydrothermal routes as well as thermal and plasma oxidation methods. In terms of advanced nanowire synthesis, the fast thermal method or direct plasma oxidation as well as the combined hybrid wet-chemical method in which copper hydroxide NWs are produced and sequentially transformed by plasma oxidation which produces Cu(2)O NWs are seen as the most promising methods to explore in the near future. These methods not only yield large quantities of NWs, but produce high quality material with advanced properties.     

Influence of copper nanoparticles on copper requiring enzyme

This study describes the influence of copper nanoparticles (CNPs) on activity and kinetic properties of a Cu²⁺ requiring sorghum oxalate oxidase (OxO). CNPs were synthesised by citrate-induced reduction of CuCl₂ and their size (range 13–58?nm) was determined by transmission electron microscopy. The CNPs were characterised by scanning electron microscopy and X-ray diffraction studies. These CNPs enhanced OxO activity by 30%. Thermal and storage stability were increased, while Km value for oxalate decreased in the presence of CNPs. CNPs protected OxO against chelation by diethyldithiocarbamate, a Cu²⁺ specific chelator. The analytic use of OxO in the presence of CNP for determination of oxalate in food stuff is demonstrated.     

Toxicity and biocompatibility of carbon nanoparticles

A review is presented of the literature data concerning the effects induced by carbon nanoparticles on the biological environment and the importance of these effects in human and animal health. The discovery in 1985 of fullerenes, a novel carbon allotrope with a polygonal structure made up solely by 60 carbon atoms, and in 1991 of carbon nanotubes, thin carbon filaments (1-3 microm in length and 1-3 nm in diameter) with extraordinary mechanical properties, opened a wide field of activity in carbon research. During the last few years, practical applications of fullerenes as biological as well as pharmacological agents have been investigated. Various fullerene-based compounds were tested for biological activity, including antiviral, antioxidant, and chemiotactic activities. Nanotubes consist of carbon atoms arranged spirally to form concentric cylinders, that are perfect crystals and thinner than graphite whiskers. They are stronger than steel but very flexible and lightweight and transfer heat better than any other known material. These characteristics make them suitable for various potential applications such as super strong cables and tips for scanning probe microscopes, as well as biomedical devices for drug delivery, medical diagnostic, and therapeutic applications. The effects induced by these nanostructures on rat lung tissues, as well as on human skin and human macrophage and keratinocyte cells are presented.     

Low-macroscopic field emission properties of wide bandgap copper aluminium oxide nanoparticles for low-power panel applications

Field emission properties of CuAlO(2) nanoparticles are reported for the first time, with a low turn-on field of approximately 2 V μm(-1) and field enhancement factor around 230. The field emission process follows the standard Fowler-Nordheim tunnelling of cold electron emission. The emission mechanism is found to be a combination of low electron affinity, internal nanostructure and large field enhancement at the low-dimensional emitter tips of the nanoparticles. The field emission properties are comparable to the conventional carbon-based field emitters, and thus can become alternative candidate for field emission devices for low-power panel applications.     

Synthesis of copper ferrite nanoparticles

Pseudospherical copper ferrite particles 20 to 90 nm in average size were prepared by an aerosol method through condensation of iron and copper vapors in an inert-gas flow, followed by the oxidation of the resulting two-phase powder under heterogeneous combustion conditions to an almost single-phase product. The nanoparticles were characterized by scanning electron microscopy, X-ray diffraction, BET measurements, and vibrating-sample magnetometry. Analysis of the X-ray diffraction data and the behavior of the magnetization of reaction intermediates and final synthesis products in the range 400–1100 K made it possible to propose models for the nanostructure of the particles and establish the likely sequence of the observed phase transformations.     

Nephron ultrastructural alterations induced by zinc oxide nanoparticles: an electron microscopic study

Due to their unique properties, zinc oxide nanoparticles (ZnO NPs) are invested in many industries, commercial products, and nanomedicine with potential risk for human health and the environment. The present study aims to focus on alterations that might be induced by ZnO NPs in the nephron ultrastructure. Male Wister Albino rats were subjected to ZnO NPs at a daily dose of 2 mg/kg for 21 days. Kidney biopsies were processed to transmission electron microscopy (TEM) and ultrastructural pathology examinations. Exposure to ZnO NPs‐induced ultrastructural alterations in the proximal convoluted tubules (PCTs) and to lesser extent in the distal ones (DCTs), while the loops of Henle were almost not affected. The glomeruli demonstrated dilatation, partial mesangial cells loss, matrix ballooning, slits filtration widening, and basement membrane thickening. Moreover, PCT revealed cytoplasmic necrosis, vacuolation, erosion, and disorganisation of the apical microvilli together with mitochondrial swelling and cristae destruction. The nuclei of the renal cells exhibited nuclear deformity, heterochromatin accumulation, and apoptotic activities. The findings indicate that ZnO nanomaterial have the potential to affect the nephron ultrastructure suggesting alteration in the kidney functions. More work is needed for better understanding the toxicity and pathogenesis of ZnO oxide nanomaterial.Inspec keywords: electron microscopy, zinc compounds, transmission electron microscopy, nanomedicine, biochemistry, diseases, cellular biophysics, biomembranes, kidney, nanofabrication, molecular biophysics, nanoparticles, II‐VI semiconductors, biomedical optical imagingOther keywords: electron microscopic study, unique properties, zinc oxide nanoparticles, ZnO NPs, nephron ultrastructure, Male Wister Albino rats, ultrastructural pathology examinations, NPs‐induced ultrastructural alterations, partial mesangial cells loss, ZnO nonmaterial, ZnO oxide nonmaterial, nephron ultrastructural alterations, kidney biopsies, time 21.0 d, ZnO     

The role of catalyst support on activity of copper oxide nanoparticles for reduction of 4-nitrophenol

Developing a facile and efficient method is an important approach for promising commercial catalytic applications. Toxic organic pollutants in waste waters are becoming a worldwide problem that threatens life on earth and prevents essential elements to sustain living organisms. Herein, the effect of catalyst support on the activity of copper oxide (CuO) nanoparticles for catalytic reduction of 4-nitrophenol (4-NP) in presence of sodium borohydride (NaBH₄)-aqueous medium was discussed. A simple and conventional wet impregnation method was used for the deposition of CuO nanoparticles on several metal oxides (Al₂O₃, SiO₂, MgO, CaO, ZnO, ZrO₂). The prepared catalysts were characterized via using techniques such as X-ray diffraction (XRD), nitrogen sorption, inductively coupled plasma-optical emission spectrometry (ICP-OES), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The effect of support material on the catalytic performance of CuO nanoparticles for the reduction of 4-NP was evaluated and the performance order of support was ZrO₂ > Al₂O₃ > SiO₂ > CaO > MgO > ZnO. CuO/ZrO₂ catalyst exhibited excellent catalytic activity and the pseudo-first-order rate constant was determined as 15.97 · 10⁻³ s⁻¹. Considering the simple preparation process and the efficient catalytic reduction of 4-NP of CuO/ZrO₂, this study opens up a marvelous chance to this material for practical application of waste water treatment.     

Application of ion implantation for synthesis of copper nanoparticles in a zinc oxide matrix for obtaining new nonlinear optical materials

We have obtained a layered composite material by implantation of single crystal zinc oxide (ZnO) substrates with 160-keV Cu⁺ ions to a dose of 10¹⁶ or 10¹⁷ cm⁻². The composite was studied by linear optical absorption spectroscopy; the nonlinear optical characteristics were determined by means of Z-scanning at a laser radiation wavelength of 532 nm. The appearance of the optical plasmon resonance bands in the spectra indicated that ion implantation to the higher dose provides for the formation of copper nanoparticles in a subsurface layer of ZnO. The new nonlinear optical material comprising metal nanoparticles in a ZnO matrix exhibits the phenomenon of self-defocusing and possesses a high nonlinear absorption coefficient (β=2.07×10⁻³ cm/W).     

Synthesis of cuprous oxide nanoparticles by mechanochemical oxidation of copper in high planetary energy ball mill

Nanoparticles cuprous oxide with an average mean crystallite size of about 11 nm was synthesized through solid state oxidation of Cu powder using a high energy planetary ball mill in oxygen atmosphere. The structural and morphological changes during process were analyzed using XRD and TEM techniques. It was found that the Johnson–Mehl–Avrami model appropriately explained the kinetics of mechanochemical synthesis of Cu₂O nanoparticles. According to the value of the Avrami exponent, the interface controlled growth was the conversion mechanisms involved during the mechanochemical oxidation of Cu powder.     

Structural,optical, and dielectric characteristics of copper oxide nanoparticles loaded CMC/PEO matrix

Journal of Materials Science - Polymer nanocomposite films were prepared using the casting method through filling a polymer mixture of carboxymethyl cellulose (CMC) and polyethylene oxide (PEO)...