Synthesis and Characterization of Monodispersed Copper Colloids in Polar Solvents

The controllable synthesis of NiO/Ni/C nanosheets via pulsed plasma in ethylene glycol solution for oxygen evolution electrocatalysis

NiO-based composites exhibit high catalytic activity for the oxygen evolution reaction (OER). Herein, high-performance NiO/Ni/C nanosheet catalysts were obtained by liquid-phase pulsed plasma (LPP), which was generated between two nickel electrodes in ethylene glycol (EG) solution by a homemade high-voltage pulse power supply. Melted nickel nanodrops were ejected from nickel electrodes which were bombarded by the energetic plasma. Simultaneously, high-temperature nickel nanodrops promoted the decomposition of the organics which were converted in the EG solution by the catalysis of LPP and formed hierarchical porous carbon nanosheets. Due to the high surface energy of the hierarchical porous carbon nanosheets, the spherical particles of Ni/NiO were adsorbed on the surface to compose the NiO/Ni/C composites. The pore size distribution of the composites could be controlled with different EG concentrations. When the EG concentration was 10 vol% (EG30), the composites possessed a H2 + H2 + H3 type pore size distribution and maximum active site area, leading to an exceptional OER activity (289.2 mV overpotential at 10 mA cm^-2).

Emilia sonchifolia leaf extract-mediated green synthesis, characterization, in vitro biological activities, photocatalytic degradation and in vivo Danio rerio embryo toxicity of copper nanoparticles

The green-mediated synthesis of copper nanoparticles is of great interest in nanotechnology and is regarded as a low-cost and environmentally beneficial method. Herein, Emilia sonchifolia leaf extract was employed as a reducing and capping agent for the green production of copper nanoparticles. In this work, we focused on the in vivo and in vitro biological studies of copper nanoparticles, which were evaluated in zebrafish (Danio rerio) embryos. The biological effects from the in vitro studies of the copper nanoparticles included cytotoxicity (in human cells) and anti-diabetic, anti-inflammatory, and antibacterial activity. Furthermore, the effectiveness of the greenly produced copper nanoparticles for photocatalysis was also evaluated, and then SEM-EDX, FTIR, XRD, TGA and UV-vis spectroscopy were used to characterise the copper nanoparticles. The results of the toxicity test on zebrafish embryos demonstrated that the green-produced copper nanoparticles had a significantly low harmful effect. According to the results, the copper nanoparticles showed dose-dependent cytotoxicity against human keratinocytes (HaCaT) and human breast cancer cells (MCF-7), which was higher than that of the Emilia sonchifolia leaf extract. The green copper nanoparticles also demonstrated more potent anti-inflammatory, antibacterial and anti-diabetic properties. In the photocatalytic experiment, the produced copper nanoparticles successfully degraded the organic methylene blue dye. Thus, it can be concluded that copper nanoparticles can be employed for drug administration in both in vitro and in vivo settings in biomedical applications. Additionally, as catalysts, these copper nanoparticles can be employed for the removal of organic dyes.

Dual-site catalysts featuring platinum-group-metal atoms on copper shapes boost hydrocarbon formations in electrocatalytic CO2 reduction

Copper-based catalyst is uniquely positioned to catalyze the hydrocarbon formations through electrochemical CO₂ reduction. The catalyst design freedom is limited for alloying copper with H-affinitive elements represented by platinum group metals because the latter would easily drive the hydrogen evolution reaction to override CO₂ reduction. We report an adept design of anchoring atomically dispersed platinum group metal species on both polycrystalline and shape-controlled Cu catalysts, which now promote targeted CO₂ reduction reaction while frustrating the undesired hydrogen evolution reaction. Notably, alloys with similar metal formulations but comprising small platinum or palladium clusters would fail this objective. With an appreciable amount of CO-Pd₁ moieties on copper surfaces, facile CO^* hydrogenation to CHO^* or CO-CHO^* coupling is now viable as one of the main pathways on Cu(111) or Cu(100) to selectively produce CH₄ or C₂H₄ through Pd-Cu dual-site pathways. The work broadens copper alloying choices for CO₂ reduction in aqueous phases.

Hybrid materials based on chitosan functionalized with green synthesized copper nanoparticles: Physico-chemical and antimicrobial analysis

Recently, the development of materials with antimicrobial properties has become a challenge under scrutiny. The incorporation of copper nanoparticles (NpCu) into a chitosan matrix appears to represent a viable strategy to contain the particles and prevent their oxidation. Regarding the physical properties, the nanocomposite films (CHCu) showed a decrease in the elongation at break (5 %) and an increase in the tensile strength of 10 % concerning chitosan films (control). They also showed solubility values lower than 5 % while the swelling diminished by 50 %, on average. The dynamical mechanical analysis (DMA) of nanocomposites revealed two thermal events located at 113° and 178 °C, which matched the glass transitions of the CH-enriched phase and nanoparticles-enriched phase, respectively. In addition, the thermogravimetric analysis (TGA) detected a greater stability of the nanocomposites. Chitosan films and the NpCu-loaded nanocomposites demonstrated excellent antibacterial capacity against Gram-negative and Gram-positive bacteria, proved through diffusion disc, zeta potential, and ATR-FTIR techniques. Additionally, the penetration of individual NpCu particles into bacterial cells and the leakage of cell content were verified by TEM. The mechanism of the antibacterial activity of the nanocomposites involved the interaction of chitosan with the bacterial outer membrane or cell wall and the diffusion of the NpCu through the cells. These materials could be applied in diverse fields of biology, medicine, or food packaging.

Improved device efficiency and lifetime of perovskite light-emitting diodes by size-controlled polyvinylpyrrolidone-capped gold nanoparticles with dipole formation

Herein, an unprecedented report is presented on the incorporation of size-dependent gold nanoparticles (AuNPs) with polyvinylpyrrolidone (PVP) capping into a conventional hole transport layer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The hole transport layer blocks ion-diffusion/migration in methylammonium-lead-bromide (MAPbBr3)-based perovskite light-emitting diodes (PeLEDs) as a modified interlayer. The PVP-capped 90 nm AuNP device exhibited a seven-fold increase in efficiency (1.5%) as compared to the device without AuNPs (0.22%), where the device lifetime was also improved by 17-fold. This advancement is ascribed to the far-field scattering of AuNPs, modified work function and carrier trapping/detrapping. The improvement in device lifetime is attributed to PVP-capping of AuNPs which prevents indium diffusion into the perovskite layer and surface ion migration into PEDOT:PSS through the formation of induced electric dipole. The results also indicate that using large AuNPs (> 90 nm) reduces exciton recombination because of the trapping of excess charge carriers due to the large surface area.

Copper Nanoparticles as Growth Promoter, Antioxidant and Anti-Bacterial Agents in Poultry Nutrition: Prospects and Future Implications

Copper (Cu) is a vital trace mineral involved in many physiological functions of the body. In the poultry industry, copper sulfate is being used as a major source of Cu. Copper in the bulk form is less available in the body, and much of its amount excreted out with feces causing environmental pollution and economic loss. The application of nanotechnology offers promise to address these issues by making nanoparticles. Copper nanoparticles (Cu-NP) are relatively more bioavailable due to their small size and high surface to volume ratio. Although, there is limited research on the use of Cu-NP in the poultry industry. Some researchers have pointed out the importance of Cu-NP as an effective alternative of chemical, anti-bacterial agents, and growth promoters. The effect of Cu-NP depends on their size, dose rate and the synthesis method. Apart from there, high bioavailability Cu-NP exhibited positive effects on the immunity of the birds. However, some toxic effects of Cu-NP have also been reported. Further investigations are essentially required to provide mechanistic insights into the role of Cu-NP in the avian physiology and their toxicological properties. This review aims to highlight the potential effects of Cu-NP on growth, immune system, antioxidant status, nutrient digestibility, and feed conversion ratio in poultry. Moreover, we have also discussed the future implications of Cu-NP as a growth promoter and alternative anti-bacterial agents in the poultry industry.

Current status of plant metabolite-based fabrication of copper/copper oxide nanoparticles and their applications: a review

Since green mode of nanoparticles (NPs) synthesis is simple, advantageous and environment friendly relative to chemical and physical procedures, various plant species have been used to fabricate copper and copper oxide nanoparticles (Cu/CuO-NPs) owing to the presence of phytochemicals which often act as capping as well as stabilizing agent. These Cu/CuO-NPs are highly stable and used in the degradation of organic dyes like methylene blue and reduction of organic compounds such as phenols. They are also used as antibacterial, antioxidant and antifungal agent due to their cytotoxicity. They are also examined for agricultural crops growth and productivity. Cu-NPs increased the root and shoot growth of mung bean. In wheat plants, these particles reduced shoot growth; and enhanced the grain yield and stress tolerance through starch degradation. Similarly, CuO-NPs treated seedlings have shown reduced chlorophyll, carotenoid and sugar content, whereas proline and anthocyanins were increased in Brassica rapa seedlings. Overall, this review presents the recent understanding of plant-mediated Cu and CuO-NPs fabrication and their application in biomedicine, environmental remediation and agricultural practices. A comparison of the traditional/conventional method of fabrication of NPs with those of green protocols has also been made. Some misconception of copper chemistry has also been critically discussed in terms of oxidation and reduction reactions.

Chitosan capped copper oxide/copper nanoparticles encapsulated microbial resistant nanocomposite films

Chitosan (CH) capped inorganic nanomaterials have been considered as significant antibacterial materials in the clinical field. This work shows the synthesis of two new different antibacterial composite films as a result of the incorporation of CH capped copper oxide (CHCuO) and copper (CHCu) nanoparticles (NPs). Here, CHCuO and CHCu NPs were achieved by a facile chemical reduction of Cu²⁺ ions using sodium hydroxide and ascorbic acid. TEM analysis revealed the morphology as rod-type nanoflakes for CHCuO and a spherical shape for CHCu NPs with ~7 ± 2 nm size. Antimicrobial activity of the developed materials was studied by the inhibition zone method, against both gram-negative and gram-positive bacteria. The antimicrobial activity revealed that the CHCuO NPs and CHCuO-CH film showed a higher inhibition zone than the other nanomaterials. The results suggested that the synthesized materials can be used in wound dressing applications.

Biosynthesis of Silver Nanoparticles from Oropharyngeal Candida glabrata Isolates and Their Antimicrobial Activity against Clinical Strains of Bacteria and Fungi

The objective of the present study was one step extracellular biosynthesis of silver nanoparticles (AgNPs) using supernatant of Candida glabrata isolated from oropharyngeal mucosa of human immunodeficiency virus (HIV) patients and evaluation of their antibacterial and antifungal potential against human pathogenic bacteria and fungi. The mycosynthesized AgNPs were characterized by color visualization, ultraviolet-visible (UV) spectroscopy, fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The FTIR spectra revealed the binding and stabilization of nanoparticles with protein. The TEM analysis showed that nanoparticles were well dispersed and predominantly spherical in shape within the size range of 2⁻15 nm. The antibacterial and antifungal potential of AgNPs were characterized by determining minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC)/ minimum fungicidal concentration (MFC), and well diffusion methods. The MBC and MFC were found in the range of 62.5⁻250 μg/mL and 125⁻500 μg/mL, which revealed that bacterial strains were more susceptible to AgNPs than fungal strains. These differences in bactericidal and fungicidal concentrations of the AgNPs were due to the differences in the cell structure and organization of bacteria and yeast cells. The interaction of AgNPs with C. albicans analyzed by TEM showed the penetration of nanoparticles inside the Candida cells, which led the formation of "pits" and "pores" that result from the rupturing of the cell wall and membrane. Further, TEM analysis showed that Candida cells treated with AgNPs were highly deformed and the cells had shrunken to a greater extent because of their interaction with the fungal cell wall and membrane, which disrupted the structure of the cell membrane and inhibited the normal budding process due to the destruction and loss of membrane integrity and formation of pores that may led to the cell death.

Bismesitoylphosphinic Acid (BAPO-OH): A Ligand for Copper Complexes and Four-Electron Photoreductant for the Preparation of Copper Nanomaterials

Bismesitoylphosphinic acid, (HO)PO(COMes)₂ (BAPO-OH), is an efficient photoinitiator for free-radical polymerizations of olefins in aqueous phase. Described here are the structures of various copper(II) and copper(I) complexes with BAPO-OH as the ligand. The complex Cu^II (BAPO-O)₂ (H₂ O)₂ is photoactive, and under irradiation with UV light in aqueous phase, it serves as a source of metallic copper in high purity and yield (>80 %). Simultaneously, the radical polymerization of acrylates can be initiated and allows the preparation of nanoparticle/polymer nanocomposites in which the metallic Cu nanoparticles are protected against oxidation. The determination of the stoichiometry of the photoreductions suggests an almost quantitative conversion from Cu^II into Cu⁰ with half an equivalent of BAPO-OH, which serves as a four-electron photoreductant.

Novel synthesis and characterization of pristine Cu nanoparticles for the non-enzymatic glucose biosensor

Non enzymatic electrochemical glucose sensing was developed based on pristine Cu Nanopartilces (NPs)/Glassy Carbon Electrode (GCE) which can be accomplished by simple green method via ocimum tenuiflorum leaf extract. Then, the affect of leaf extract addition on improving Structural, Optical and electrochemical properties of pristine cu NPs was investigated. The synthesized Cu NPs were characterized with X-ray diffraction (X-ray), Uv-Visible spectroscopy (Uv-Vis), Fourier transformation infrared spectroscopy (FTIR), Particle size distribution (PSA), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) for structural optical and morphological studies respectively. The synthesized Cu NPs were coated over glassy carbon electrode (GCE) to study the electrochemical response of glucose by cyclic voltammetry and ampherometer. The results indicates that the modified biosensor shows a remarkable sensitivity (1065.21 μA mM^-1 cm^-2), rapid response time (<3s), wide linear range (1 to 7.2 mM), low detection limit (0.038 μM at S/N = 3). Therefore, the prepared Cu NPs by the Novel Bio-mediated route were exploited to construct a non-enzymatic glucose biosensor for sustainable clinical field applications.

Synthesis of Cu-Nanoparticle Hydrogel with Self-Healing and Photothermal Properties

Copper (Cu) nanoparticles possess unusual electrical, thermal, and optical properties. However, applications of these materials are often limited by their tendency to oxidize. We prepared Cu nanoparticles by a simple polyol method, with a good control over the particle size. The reaction required no inert atmosphere or surfactant agents. The as-prepared Cu nanoparticles showed good resistance to oxidation in solution. These Cu nanoparticles were then incorporated into a biocompatible polysaccharide hydrogel, which further stabilized the nanoparticles. The hybrid hydrogel exhibited a rapid self-healing ability. Because of the excellent photothermal conversion properties of the embedded Cu nanoparticles, the hybrid hydrogel showed rapid temperature elevation under laser irradiation. The hybrid hydrogel showed limited cytotoxicity; however, under laser irradiation the hydrogel displayed antibacterial properties owing to the heating effects. This study demonstrates that our hybrid hydrogel may have applications in biomedical fields and photothermal therapy.

Rational design of hierarchically-structured CuBi2O4 composites by deliberate manipulation of the nucleation and growth kinetics of CuBi2O4 for environmental applications

A versatile, eco-friendly synthesis scheme was developed to fabricate a series of hierarchically-structured CuBi2O4 composites for environmental applications. By simple tuning of the synthesis protocol (i.e. controlling the ethylene glycol to water ratio in the reaction matrix and employing different auxiliary metal precursors consisting of Cu(2+), Co(2+) or Fe(3+) species), deposition of various metal oxides on CuBi2O4 was achieved. The proposed one-pot synthesis protocol utilizes the fast nucleation and controlled growth kinetics of CuBi2O4 to deliberately immobilize the desired metal oxides on the surface of the CuBi2O4. The manipulation of the diffusion rate, mass transfer kinetics and atomic mobility of the metal precursors by controlling the viscosity and dielectric properties of the reaction matrix lead to the formation of different CuBi2O4 composites with the desired properties. The synergistic coupling effect between the CuBi2O4 and deposited metal oxide contributed to the superior performance of the novel CuBi2O4 composites. The CuBi2O4 composites demonstrate excellent potential for various environmental applications such as being a catalyst for generating sulfate radicals from peroxymonosulfate for organic pollutant removal in water and being a disinfectant. The proposed green synthesis protocol is simple and offers flexibility for fabricating hierarchically-structured CuBi2O4 composites with enhanced properties for targeted applications.

Antimicrobial electrospun silver-, copper- and zinc-doped polyvinylpyrrolidone nanofibers

The use of electrospun polyvinylpyrrolidone (PVP) nanofibers containing silver, copper, and zinc nanoparticles was studied to prepare antimicrobial mats using silver and copper nitrates and zinc acetate as precursors. Silver became reduced during electrospinning and formed nanoparticles of several tens of nanometers. Silver nanoparticles and the insoluble forms of copper and zinc were dispersed using low molecular weight PVP as capping agent. High molecular weight PVP formed uniform fibers with a narrow distribution of diameters around 500 nm. The fibers were converted into an insoluble network using ultraviolet irradiation crosslinking. The efficiency of metal-loaded mats against the bacteria Escherichia coli and Staphylococcus aureus was tested for different metal loadings by measuring the inhibition of colony forming units and the staining with fluorescent probes for metabolic viability and compromised membranes. The assays included the culture in contact with mats and the direct staining of surface attached microorganisms. The results indicated a strong inhibition for silver-loaded fibers and the absence of significant amounts of viable but non-culturable microorganisms. Copper and zinc-loaded mats also decreased the metabolic activity and cell viability, although in a lesser extent. Metal-loaded fibers allowed the slow release of the soluble forms of the three metals.

High-Concentration Synthesis of Sub-10-nm Copper Nanoparticles for Application to Conductive Nanoinks

A simple, high-concentration (up to 0.6 M Cu salt) synthesis of sub-10-nm copper nanoparticles (Cu NPs) was developed in ethylene glycol at room temperature under ambient air conditions using 1-amino-2-propanol (AmIP) as the stabilizer. Monodispersed AmIP-Cu NPs of 3.5 ± 1.0 nm were synthesized in a high yield of ∼90%. Thus, nearly 1 g of sub-10-nm Cu NP powder was obtained using a one-step synthesis for the first time. It is proposed that metallacyclic coordination stability of a five-membered ring type between the Cu and AmIP causes the high binding force of Am IP onto the Cu surface, resulting in the superior stability of the AmIP-Cu NPs in a solution. The purified powder of AmIP-Cu NPs can be redispersed in alcohol-based solvents up to high Cu contents of 45 wt % for the preparation of Cu nanoink. The resistivity of the conductive Cu film obtained from the Cu nanoink was 30 μΩ cm after thermal heating at 150 °C for 15 min under a nitrogen flow. The long-term resistance stability of the Cu film under an air atmosphere was also demonstrated.

Low-current field-assisted assembly of copper nanoparticles for current collectors

Current collectors are essential features of batteries and many other electronic devices being responsible for efficient charge transport to active electrode materials. Three-dimensional (3D), high surface area current collectors considerably improve the performance of cathodes and anodes in batteries, but their technological implementation is impeded by the complexity of their preparation, which needs to be simple, fast, and energy efficient. Here we demonstrate that field-stimulated assembly of ∼3 nm copper nanoparticles (NPs) enables the preparation of porous Cu NP films. The use of NP dispersions enables 30× reduction of the deposition current for making functional 3D coatings. In addition to high surface area, lattice-to-lattice connectivity in the self-assembly of NPs in 3D structures enables fast charge transport. The mesoscale dimensions of out-of-plane features and the spacing between them in Cu films made by field-stimulated self-assembly of NPs provides promising morphology for current collection in lithium ion batteries (LIBs). Half-cell electrochemical models based on self-assembled films show improved specific capacity, total capacity, and cycling performance compared to traditional flat and other 3D current collectors. While integration of active electrode material into the 3D topography of the current collector needs to be improved, this study indicates that self-assembled NP films represent a viable manufacturing approach for 3D electrodes.

Copper Nanoparticles: Synthetic Strategies, Properties and Multifunctional Application

Copper nanoparticles received much attention due to its high electrical conductivity, high melting point, low electrochemical migration behavior and low cost. Top down (physical methods) and bottom up (chemical and biological) approaches adopted for the synthesis of copper nanoparticles are reported. The property of copper nanoparticles mainly depends on the synthesis route and their process parameters. The influence of process parameters on the morphology, growth and yield of the nanoparticles by adopting various synthesis methods are discussed in detail. From the earlier reports, it is proved that electrochemical and chemical reduction method have received much higher attention due to their simple operation, low cost, faster reaction rate, high yield, environment friendly and low energy consumption. The characterization techniques, advantages and limitations of each synthesis methods are also discussed. The extensive applications of copper nanoparticles in various fields are also highlighted.

Green Synthesis of Novel Jasmine Bud-Shaped Copper Nanoparticles

Novel jasmine bud-shaped copper nanoparticles were synthesized by a green chemical reduction method using polyvinylpyrrolidone (PVP) as a capping agent, L-ascorbic acid (AA) as a reducing agent as well as antioxidant agent, isonicotinic acid hydrazide (INH) as a reducing agent, and water as a solvent at 60–70°C (pH-7) in the presence of air. The UV-Vis absorption maximum obtained is 573 nm. The crystal lattice (fcc) structure of Cu Nps was confirmed by X-ray diffraction (XRD). The novel jasmine bud shape was visualized in a transmission electron microscope (TEM). The height of single copper nanobud was 6.41 nm as measured by atomic force microscope (AFM). The average particle size 6.95 nm is obtained by XRD results. Antibacterial activity of the Cu nanobuds was evaluated by testing against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria.

Interference of CuO nanoparticles with metal homeostasis in hepatocytes under sub-toxic conditions

Copper oxide nanoparticles (CuO-NP) were studied for their toxicity and mechanism of action on hepatocytes (HepG2), in relation to Cu homeostasis disruption. Indeed, hepatocytes, in the liver, are responsible for the whole body Cu balance and should be a major line of defence in the case of exposure to CuO-NP. We investigated the early responses to sub-toxic doses of CuO-NP and compared them to equivalent doses of Cu added as salt to see if there is a specific nano-effect related to Cu homeostasis in hepatocytes. The expression of the genes encoding the Cu-ATPase ATP7B, metallothionein 1X, heme oxygenase 1, heat shock protein 70, superoxide dismutase 1, glutamate cysteine ligase modifier subunit, metal responsive element-binding transcription factor 1 and zinc transporter 1 was analyzed by qRT-PCR. These genes are known to be involved in response to Cu, Zn and/or oxidative stresses. Except for MTF1, ATP7B and SOD1, we clearly observed an up regulation of these genes expression in CuO-NP treated cells, as compared to CuCl2. In addition, ATP7B trafficking from the Golgi network to the bile canaliculus membrane was observed in WIF-B9 cells, showing a need for Cu detoxification. This shows an increase in the intracellular Cu concentration, probably due to Cu release from endosomal CuO-NP solubilisation. Our data show that CuO-NP enter hepatic cells, most probably by endocytosis, bypassing the cellular defence mechanism against Cu, thus acting as a Trojan horse. Altogether, this study suggests that sub-toxic CuO-NP treatments induce successively a Cu overload, a Cu-Zn exchange on metallothioneins and MTF1 regulation on both Cu and Zn homeostasis.

Copper-based conductive composites with tailored thermal expansion

We have devised a moderate temperature hot-pressing route for preparing metal-matrix composites which possess tunable thermal expansion coefficients in combination with high electrical and thermal conductivities. The composites are based on incorporating ZrW2O8, a material with a negative coefficient of thermal expansion (CTE), within a continuous copper matrix. The ZrW2O8 enables us to tune the CTE in a predictable manner, while the copper phase is responsible for the electrical and thermal conductivity properties. An important consideration in the processing of these materials is to avoid the decomposition of the ZrW2O8 phase. This is accomplished by using relatively mild hot-pressing conditions of 500 °C for 1 h at 40 MPa. To ensure that these conditions enable sintering of the copper, we developed a synthesis route for the preparation of Cu nanoparticles (NPs) based on the reduction of a common copper salt in aqueous solution in the presence of a size control agent. Upon hot pressing these nanoparticles at 500 °C, we are able to achieve 92-93% of the theoretical density of copper. The resulting materials exhibit a CTE which can be tuned between the value of pure copper (16.5 ppm/°C) and less than 1 ppm/°C. Thus, by adjusting the relative amount of the two components, the properties of the composite can be designed so that a material with high electrical conductivity and a CTE that matches the relatively low CTE values of semiconductor or thermoelectric materials can be achieved. This unique combination of electrical and thermal properties enables these Cu-based metal-matrix composites to be used as electrical contacts to a variety of semiconductor and thermoelectric devices which offer stable operation under thermal cycling conditions.

Molecular responses of mouse macrophages to copper and copper oxide nanoparticles inferred from proteomic analyses

The molecular responses of macrophages to copper-based nanoparticles have been investigated via a combination of proteomic and biochemical approaches, using the RAW264.7 cell line as a model. Both metallic copper and copper oxide nanoparticles have been tested, with copper ion and zirconium oxide nanoparticles used as controls. Proteomic analysis highlighted changes in proteins implicated in oxidative stress responses (superoxide dismutases and peroxiredoxins), glutathione biosynthesis, the actomyosin cytoskeleton, and mitochondrial proteins (especially oxidative phosphorylation complex subunits). Validation studies employing functional analyses showed that the increases in glutathione biosynthesis and in mitochondrial complexes observed in the proteomic screen were critical to cell survival upon stress with copper-based nanoparticles; pharmacological inhibition of these two pathways enhanced cell vulnerability to copper-based nanoparticles, but not to copper ions. Furthermore, functional analyses using primary macrophages derived from bone marrow showed a decrease in reduced glutathione levels, a decrease in the mitochondrial transmembrane potential, and inhibition of phagocytosis and of lipopolysaccharide-induced nitric oxide production. However, only a fraction of these effects could be obtained with copper ions. In conclusion, this study showed that macrophage functions are significantly altered by copper-based nanoparticles. Also highlighted are the cellular pathways modulated by cells for survival and the exemplified cross-toxicities that can occur between copper-based nanoparticles and pharmacological agents.

Microwave assisted rapid synthesis and biological evaluation of stable copper nanoparticles using T. arjuna bark extract

Terminalia arjuna (T. arjuna) bark extract is used to reduce Cu(2+)→Cu(0) under microwave irradiation. The formation of copper nanoparticles (CuNPs) is monitored by recording the UV-Vis absorption spectra for surface plasmon resonance (SPR) peak, ~535 nm. The intensity of SPR increased linearly with increasing temperature of the reaction mixture. The formation mechanism of CuNPs is supported by the observed marginal decrease in pH and an increase in solution potential (E) of the reaction mixture. X-ray diffraction (XRD) pattern of the CuNPs agrees with the reported data for Cu metal and the crystallite size is ~23 nm. Fourier transform infrared spectroscopy (FT-IR) and solid-state (13)C NMR shows the presence of plant residues on the CuNPs, i.e., in situ bio-capping is possible by this method. Thermo gravimetric (TG) analysis shows the thermal degradation of plant residue and the conversion of Cu to CuO. Field emission electron microscopic (FESEM) image shows uniform spherical particles obtained here. Elemental analysis by energy dispersive X-ray (EDX) analysis confirms the presence of Cu alone, as expected. The in vitro antimicrobial activity is found to be effective for CuNPs dried at RT when compared to CuNPs dried at 70 °C. In addition, CuNPs shows very good antioxidant property.