Presence Of CuNPs Research Articles

Polyelectrolyte Platforms with Copper Nanoparticles as a Multifunctional System Aimed at Healing Process Support

(1) Purpose: The aim of the study was to develop a nanocomposite with copper nanoparticles constituting a bacteriostatic surface to maintain human lung cell function. (2) Methods: A polyelectrolyte layer coating that incorporated copper nanoparticles was designed. As a bacteriostatic factor, copper nanoparticles were applied as a colloidal solution of copper nanoparticles (ColloidCuNPs) and a solution of copper nanoparticles (CuNPs). The influence of the polyelectrolytes on selected Gram (+) and Gram (−) strains was examined. The function and morphology of the human adenocarcinoma A549 cell line, comprising human epithelial lung cells cultured in the presence of nanocomposite layer coatings, were evaluated. We applied fluorescence and scanning electron microscopies, as well as flow cytometry, for these studies. Furthermore, the layer coating material was characterized by atomic force microscopy (AFM) and energy dispersive X-ray analysis (EDX). (3) Results: It was observed that the polyelectrolytes polyethyleneimine (PEI) and poly-L-lysine (PLL) did not induce proliferation of the E. coli strain. However, they did induce the proliferation of the S. aureus strain. Due to the effectiveness of the CuNPs against the E. coli strain, CuNPs were selected for further research. The designed coatings of proper NPs shared the sustained function of human lung cells within 10 days of culture. The AFM and EDX characterization confirmed the presence of copper in the layer coating nanomaterial. The presence of CuNPs in polyethyleneimine-based nanocomposite deepened the bacteriostatic effect on E. coli compared with PEI alone. Meanwhile, incorporating CuNPs in PLL allowed A549 cell maintenance but did not exert a bacteriostatic influence on the examined strain. (4) Conclusions: The platform based on polyelectrolytes, incorporated with copper nanoparticles, that ensures the growth and appropriate morphology of the human lung epithelial cells, might be considered an element of a system for medical devices used to maintain the function of human lung cells.

Copper nanoparticles from acid ascorbic: Biosynthesis, characterization, in vitro safety profile and antimicrobial activity

Pressure injuries (PIs) are interruptions in the skin that cause great discomfort in bedridden patients and their treatment generates a lot of waste and equal discomfort, requiring alternative materials for their treatment. Thus, this work aims to synthesize and characterize copper nanoparticles (CuNPs) by the biosynthesis method from ascorbic acid for possible application in tissue engineering. CuNPs were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, zeta potential (ZP), Attenuated Total Reflection Fourier Transform Infrared (ATR-FT-IR) spectroscopy, Field Emission Gun Scanning Electron Microscopy (FEG-SEM) and Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDX). The safety profile was performed in vitro cytotoxicity MTT assay in the Vero cell line at different time intervals (24, 48 and 72 h). The antibacterial potential was evaluated by minimal inhibitory activity (MIC) against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 13883) and Klebsiella pneumoniae (ATCC 27853). The XRD diffractogram showed characteristic peaks of CuNPs with a cubic face structure representing metallic copper at 43.31° (111) plane with an average particle size of 43.6 nm. The micrograph of CuNPs showed heterogeneous clusters, with SBET = 8 ± 0.05 m2 g−1, Vp = 0.04 ± 0.02 cm³ g−1 and ZP = −29.63 ± 2.31 mV and H2-type hysteresis. EDX results indicated the presence of CuNPs and the effectiveness of the biosynthesis process. The safety profile showed that 12.5 μg mL−1 was the maximum concentration accepted by cells, and that the damage caused in Vero cells was due to the generation of reactive oxygen species after 72 h. Regarding antimicrobial activity, CuNPs show greater inhibition and selectivity for gram-negative bacteria, such as P. aeruginosa (0.625 mg mL−1), K. pneumoniae (0.156 mg mL−1) and E. coli (0.625 mg mL−1) due to the greater affinity of Cu+2 ions with the structure of the cell wall. Therefore, to highlight the potential of CuNPs synthesized from ascorbic acid by biosynthesis for a possible application in tissue engineering.

Evidence of Copper Nanoparticles and Poly I:C Modulating Cas9 Interaction and Cleavage of COR (Conserved Omicron RNA).

Conserved omicron RNA (COR) is a 40 base long 99.9% conserved sequence in SARS-CoV-2 Omicron variant, predicted to form a stable stem loop, the targeted cleavage of which can be an ideal next step in controlling the spread of variants. The Cas9 enzyme has been traditionally utilized for gene editing and DNA cleavage. Previously Cas9 has been shown to be capable of RNA editing under certain conditions. Here we investigated the ability of Cas9 to bind to single-stranded conserved omicron RNA (COR) and examined the effect of copper nanoparticles (Cu NPs) and/or polyinosinic-polycytidilic acid (poly I:C) on the RNA cleavage ability of Cas9. The interaction of the Cas9 enzyme and COR with Cu NPs was shown by dynamic light scattering (DLS) and zeta potential measurements and was confirmed by two-dimensional fluorescence difference spectroscopy (2-D FDS). The interaction with and enhanced cleavage of COR by Cas9 in the presence of Cu NPs and poly I:C was shown by agarose gel electrophoresis. These data suggest that Cas9-mediated RNA cleavage may be potentiated at the nanoscale level in the presence of nanoparticles and a secondary RNA component. Further explorations in vitro and in vivo may contribute to the development of a better cellular delivery platform for Cas9.

Novel green formulation of copper nanoparticles by Foeniculum vulgare: Chemical characterization and determination of cytotoxicity, anti-human lung cancer and antioxidant effects

The use of nanoparticles has increased significantly in domestic and industrial processes in recent years. These particles show special physical and chemical behavior due to their high surface-to-volume ratio, small size, and visual characteristics related to their size. Metal nanoparticles are widely used in the fields of biotechnology, bioassays, clinical diagnosis and treatment, food safety, and water and wastewater treatment. In the present study, copper nanoparticles were green-synthesized using the aqueous extract of Foeniculum vulgare leaf aqueous extract. The synthesized Cu NPs were characterized by analytical techniques including energy dispersive X-ray analysis (EDX), field emission scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD), ultraviolet–visible (UV–vis) spectroscopy, and fourier transform infrared spectroscopy (FTIR). The anti-human lung cancer activity of Cu NPs was evaluated using MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The nanoparticles were formed in a spherical shape in the range size of 33.62 to 74.81 nm. In the antioxidant test, the IC50 of Foeniculum vulgare, Cu NPs, and butylated hydroxytoluene (BHT) against 2,2-diphenylpicrylhydrazyl (DPPH) free radicals were 99, 42, and 26 µg/mL, respectively. In the cellular and molecular part of the recent study, the treated cells with Cu NPs were assessed by MTT assay for 48 h about the cytotoxicity and anti-human lung cancer properties on normal (human umbilical vein endothelial cells (HUVECs)) and lung cancer cell lines i.e., NCI-H2126, NCI-H1299, and NCI-H1437. The IC50 of Cu NPs were 108, 168, and 122 µg/mL against NCI-H2126, NCI-H1299, and NCI-H1437 cell lines, respectively. The viability of malignant lung cell line reduced dose-dependently in the presence of Cu NPs. The IC50 of Foeniculum vulgare leaf aqueous extract were 594, 781, and 610 µg/mL against NCI-H2126, NCI-H1299, and NCI-H1437 cell lines, respectively.

Biosynthesis of copper nanoparticles using symbiotic bacterium Xenorhabdus sp, isolated from entomopathogenic nematode and its antimicrobial and insecticidal activity against Spodoptera litura

The field bio-nanotechnology has provided insight in creation of biosynthetic nanomaterials. Nanoparticles synthesis by entomopathogenic microbes are considered as the novel methods and gained worldwide attention in the field of pest control. This study focused on the synthesis and characterization of CuNPs using Xenorhabdus sp, and their antimicrobial and larvicidal activities with potted plant experiments. 335 nm λmax at UV-Vis spec indicates the presence of CuNPs and functional groups such as alcohols and phenols were confirmed. SEM revealed the clustered shape. EDaX confirms the composition of copper. Crystalline nature were observed in XRD. TEM indicates the particles ranging from 5 to 20nm.The antimicrobial activity against E. coli, P. aeruginosa and Fusarium sp, shows higher zone of inhibition. Larvicidal activity of S. litura shows highest mortality. In potted plant experiment, less damage was observed in CuNPs. Our experiment concludes that, CuNPs synthesized, has highest insecticidal and antimicrobial activity, which can be used in biopesticides.

Anti-human lung adenocarcinoma, cytotoxicity, and antioxidant potentials of copper nanoparticles green-synthesized by Calendula officinalis

Calendula officinalis is known as a popular plant with various uses as pharmaceutical agent or food additive around the world. In this study, cooper nanoparticles were green synthesized using the aqueous extract of Calendula officinalis as the stabilizing, reducing, and capping agents. The formation of CuNPs@C. officinalis was screened using different chemical technique such as FT-IR spectroscopy, XRD, SEM, and Energy EDS. The antioxidant and anti-cancer activity of CuNPs@C. officinalis was studied using common assay including free radical scavenging and MTT assays. The results confirm the green synthesized of CuNPs@C. officinalis with aspherical morphology in the range size of 19.64 to 39.15 nm. In the antioxidant test, the IC50 of CuNPs@C. officinalis and BHT against DPPH free radicals were 193 and 154 µg/mL, respectively. In the cellular and molecular part of the recent study, the treated cells with CuNPs@C. officinalis were assessed by MTT assay for 24, 48, and 72 h about the cytotoxicity and anti-human lung adenocarcinoma properties on normal (HUVEC) and lung adenocarcinoma cell lines, i.e. lung moderately differentiated adenocarcinoma (LC-2/ad), lung poorly differentiated adenocarcinoma (PC-14), and lung well-differentiated bronchogenic adenocarcinoma (HLC-1). The IC50s of CuNPs@C. officinalis were 297, 328, and 514 µg/mL against PC-14, LC-2/ad, and HLC-1 cell lines, respectively. The viability of malignant lung cell line reduced dose-dependently in the presence of CuNPs@C. officinalis. It seems that the anti-human lung adenocarcinoma effect of recent nanoparticles is due to their antioxidant effects.

Enzyme-free colorimetric nanosensor for the rapid detection of lactic acid in food quality analysis

Lactic acid is an essential organic chemical in food, clinical, chemical, and bioprocessing industries. We are reporting for the first time, a rapid and facile enzyme-free colorimetric sensor for the detection of lactic acid (LA) in food samples using nitrophenol ( p -NP) added copper nanoparticles (CuNPs). The responses of p -NP (5 mmol/L) to lactic acid in the presence of CuNPs were reported by analysing the UV-VIS absorption spectra in an aqueous solution. CuNPs were synthesized by the chemical reduction method and were identified to be in the Cubic phase using XRD analysis. The sample characterization studies were performed using the SEM, UV for obtaining good optical and selective lactic acid-sensing properties. The sensing mechanism is due to the aggregation responses of CuNPs conjugated p -NP in the presence of lactic acid as seen in the UV-VIS absorption spectra shift studied in an aqueous solution. The absorption spectrum of p -NP exhibited one intense band at 402 nm in the presence of CuNPs. Although the addition of lactic acid may cause π –π* transitions led to a hypsochromic shift (blue shift) with a subtle decrease in the wavelength from 402 to 315 nm, the solution underwent from being colored (greenish-yellow) to colorless. The stoichiometric ratio of a binding event is explained using Job's plot. The naked eye colorimetric response of the sensor-enabled detection limit of lactic acid to 0.33 mM. The sensor studies were compared with standard LC-MS/MS revealing a good recovery (95%) in food samples. This method is facile and alternate to the current high-cost techniques and enzymatic sensors. Schematic illustration of colorimetric sensor- CuNPs assisted catalytic reduction of p -nitrophenol (colored) to p -aminophenol (colorless) with the exposure of lactic acid. • Nonenzymatic colorimetric nanosensor for lactic acid detection. • The visual detection of trace amounts of lactic acid as low as 0.33 mM. • Sensor is based on the catalytic activity of copper nanoparticles. • Application of developed sensor for real time food sample analysis.

SDS capped Cu nanorods: photosynthesis, stability, and their catalytic activity for trypan blue oxidative degradation

Sodium dodecyl sulfate (SDS) capped- Cu nanorods were prepared by using ascorbic acid under light limiting diode (LED) irradiation for the first time. The preliminary indications of CuNPs production were the appearance of yellow (Cu2O) and red-chocolate color (Cu0) in absence and presence of LED exposure at room temperature. The optical, spectroscopic and morphological properties of as-prepared NPs were characterized using UV–visible spectroscopy through the presence of a characteristic surface Plasmon resonance (SPR) band for Cu0 at 584 nm along with high absorbance at 800 nm for Cu2O. X-ray diffraction (XRD) shows that the red-chocolate color consist 90% metallic Cu0 and 9.7% Cu2O with face cubic center unit cell structure of CuNPs. Transmission electron microscope (TEM), energy dispersive X-ray (EDX), and scanning electron microscope (SEM) revealed that the CuNPs were nano-rods with an average length ranging from 300 to 350 nm. LED light assisted degradation of trypan blue (TB) was also investigated in presence of CuNPs and K2S2O8. The existence of sulfate radicals (SO4-•) and hydroxly radicals (HO•) generated during the degradation were identified by using different radical scavengers. Degradation follows first-order kinetics with respect to K2S2O8 concentrations. The oxidative dissolution of CuNPs was also observed along with the TB degradation. Based on the absorbance changes at 590 nm, the degradation and dissolution mechanisms were proposed and discussed.

New insights into mechanisms of copper nanoparticle toxicity in freshwater algae Chlamydomonas reinhardtii: Effects on the pathways of secondary metabolites

The effects of copper nanoparticles (Cu-NPs), including their stability in the medium, were studied with the green unicellular algae Chlamydomonas reinhardtii (CC-125). Cu-NPs were synthesized and characterized. Cu-NP particles were uniform, regular, and largely spherical, and they had smooth surfaces; the average size was estimated to be 137.4 ± 2.1 nm. Chlamydomonas cells were cultivated for 96 h under controlled conditions in the presence of Cu-NPs, according to OECD guidelines, and then subjected to toxicological bioassays. Based on scanning electron microscopy (SEM) observations, the effects of Cu-NPs resulted in part from the dissolution of nanoparticles (NPs) and the action of copper itself, which shows the importance of studying NP stability in the testing environment. In this assay, deleterious effects were enhanced by increasing Cu-NP concentrations (5, 10, 25, 50, and 100 mg/L). Concentrations higher than 25 mg/L exhibited extreme toxicity. We confirmed the known toxic effects of metal NPs, namely, growth inhibition, reduction of chlorophyll levels in cells, cell penetration and increased ROS production. Attention was also paid to select underexplored metabolites, which were studied with a LC-MS/MS system. Treatments caused changes in metabolites profiles, and levels of p-hydroxybenzaldehyde and protocatechuic acid were especially enhanced, suggesting their positive roles in the antioxidant defence response. Furthermore, a repeatable increase in suberic acid levels was observed for various stress conditions tested, and we expect that this was the result of lipid peroxidation.

Rainbow trout (Oncorhynchus mykiss) chemosensory detection of and reactions to copper nanoparticles and copper ions

Copper is known to interfere with fish olfaction. Although the chemosensory detection and olfactory toxicity of copper ions (Cu2+) has been heavily studied in fish, the olfactory-driven detection of copper nanoparticles (CuNPs)—a rapidly emerging contaminant to aquatic systems—remains largely unknown. This study aimed to investigate the olfactory response of rainbow trout to equitoxic concentrations of CuNPs or Cu2+ using electro-olfactography (EOG, a neurophysiological technique) and olfactory-mediated behavioural assay. In the first experiment, the concentration of contaminants known to impair olfaction by 20% over 24 h (EOG-based 24-h IC20s of 220 and 3.5 μg/L for CuNPs and Cu2+, respectively) were tested as olfactory stimuli using both neurophysiological and behavioural assays. In the second experiment, to determine whether the presence of CuNPs or Cu2+ can affect the ability of fish to perceive a social cue (taurocholic acid (TCA)), fish were acutely exposed to one form of Cu-contaminants (approximately 15 min). Following exposure, olfactory sensitivity was measured by EOG and olfactory-mediated behaviour within a choice maze was recorded in the presence of TCA. Results of neurophysiological and behavioural experiments demonstrate that rainbow trout can detect and avoid the IC20 of CuNPs. The IC20 of Cu2+ was below the olfactory detection threshold of rainbow trout, as such, fish did not avoid Cu2+. The high sensitivity of behavioural endpoints revealed a lack of aversion response to TCA in CuNP-exposed fish, despite this change not being present utilizing EOG. The reduced response to TCA during the brief exposure to CuNPs may be a result of either olfactory fatigue or blockage of olfactory sensory neurons (OSNs) by CuNPs. The observed behavioural interference caused by CuNP exposure may indicate that CuNPs have the ability to interfere with other behaviours potentially affecting fitness and survival. Our findings also revealed the differential response of OSNs to CuNPs and Cu2+.

Electropolymerization of chitosan in the presence of CuNPs on the surface of a copper electrode: an advanced nanocomposite for the determination of mefenamic acid and indomethacin in human plasma samples and prevention of drug poisoning

An innovative method was introduced for the electro-polymerization of chitosan on the surface of a copper electrode.

Thiol stabilized copper nanoparticles exert antimicrobial properties by preventing cell division in Escherichia coli

The uses of metallic nanoparticles have gained importance as one of the therapeutic options to treat infections. Here, we synthesized stable copper nanoparticles (CuNPs) using Thiosalicylic acid and assessed their antimicrobial activities against various Gram-negative bacteria. The synthesized CuNPs had absorption maxima of 570 nM with a size range of 5-11 nM and face-centred cubic (Fcc) crystal structure. The bacterial cells in their planktonic and sessile forms were susceptible to CuNPs. The nanoparticles did not show any cytotoxicity to murine macrophages (RAW264.7) below 60 µg/mL. However, the expression of oxidative stress defence gene ahpC revealed the possibility of ROS generation upon treatment with CuNPs. Interestingly, the cell division proteins like, FtsZ and FtsI were destabilized in the presence of CuNPs which in turn inhibited bacterial cell division. In conclusion, it may be stated that the synthesized CuNPs can kill bacteria by arresting cell division and/or by ROS generation.

Efficient alternative of antimicrobial nanocomposites based on cellulose acetate/Cu-NPs

ABSTRACTThe current research presents an efficient, cheap, and safe antimicrobial material for widespread use based on copper nanoparticles (Cu-NPs) loaded on cellulose acetate (CA) matrix. A reduction process of CuSO4·5H2O has been performed to prepare Cu-NPs. The nanosized copper particles included oxidized Cu (15–20 nm). Two different loads of Cu-NPs were used in this study, 2% and 6% mol.%. The presence of Cu-NPs incorporated with CA films slightly affected the tensile index of the films, where low and high-loaded Cu-NPs enhanced the tensile index by small values ranged from 0.640 to 0.650 and 0.667, respectively. A study on the antibacterial activity of these nanocomposites was carried out for Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. It has been found that CA containing Cu-NPs (2%) exhibited the highest antimicrobial activity against all test microbes including S. aeureus (21 mm), P. aeruginosa (18 mm), C. albicans (19 mm), and Aspergillus niger (15 mm). Results also revealed that CA film with 6% exhibited lower activity than film with 2% Cu-NPs. The morphological properties of CA/Cu-NPs films were characterized by scanning electron microscopy and transmission electron microscope in addition to X-ray diffraction. Low-loaded Cu-NPs showed homogenous distribution through CA matrix while, the high-loaded Cu-NPs were agglomerated through CA matrix. Thermal properties illustrated the enhancement of thermal stability of the film with increasing the loaded Cu-NPs.

Formation of copper nanoparticles in LTL nanosized zeolite: spectroscopic characterization.

The state of copper species stabilized in nanosized LTL zeolite subjected to various post-synthesis treatments was unveiled by a range of spectroscopic techniques. FTIR and UV-Vis studies demonstrated that the reduction process of copper in the LTL nanosized zeolite leads to the formation of different species including Cu2+, Cu+ and Cu nanoparticles (Cu NPs). The adsorption of probe molecules (NO and CO) was used to selectively monitor the copper species in the LTL nanosized zeolite upon oxidation and reduction post-synthesis treatments. Both the Cu2+ and Cu+ species were probed by NO and CO, respectively. The amount of Cu+ in the LTL zeolite nanocrystals was about 43% as determined by FTIR, while the amount of Cu NPs was about 55% determined by the UV-Vis spectroscopic characterization. These results were complemented by EPR, 29Si and 63Cu MAS NMR spectroscopic data. The EPR spectroscopy was further applied to monitor the effective reduction of the Cu2+ species and their re-oxidation, while the 63Cu MAS NMR verified the presence of Cu NPs in the LTL nanosized zeolite crystals.

Investigating nanohybrid material based on 3D CNTs@Cu nanoparticle composite and imprinted polymer for highly selective detection of chloramphenicol

Nanotechnology holds great promise for the fabrication of versatile materials that can be used as sensor platforms for the highly selective detection of analytes. In this research article we report a new nanohybrid material, where 3D imprinted nanostructures are constructed. First, copper nanoparticles are deposited on carbon nanotubes and then a hybrid structure is formed by coating molecularly imprinted polymer on 3D CNTs@Cu NPs; and a layer by layer assembly is achieved. SEM and AFM revealed the presence of Cu NPs (100–500nm) anchored along the whole length of CNTs, topped with imprinted layer. This material was applied to fabricate an electrochemical sensor to monitor a model veterinary drug, chloramphenicol. The high electron transfer ability and conductivity of the prepared material produced sensitive response, whereas, molecular imprinting produces selectivity towards drug detection. The sensor responses were found concentration dependent and the detection limit was calculated to be 10μM (S/N=3). Finally, we showed how changing the polymer composition, the extent of cross linking, and sensor layer thickness greatly affects the number of binding sites for the recognition of drug. This work paves the way to build variants of 3D imprinted materials for the detection of other kinds of biomolecules and antibiotics.

In vitro effects of copper nanoparticles on plant pathogens, beneficial microbes and crop plants

Copper-based chemicals are effectively used as antimicrobials in agriculture. However, with respect to its nanoparticulate form there has been limited number of studies. In this investigation, in vitro tests on effect of copper nanoparticles (CuNPs) against plant pathogenic fungi, oomycete, bacteria, beneficial microbes Trichoderma harzianum and Rhizobium spp., and wheat seeds were conducted. Integration of CuNPs with non-nano copper like copper oxychloride (CoC) at 50 mg/L concentration each recorded 76% growth inhibition of the oomycete Phytophthora cinnamomi in vitro compared to the control. CuNPs also showed synergistic inhibitory effect with CoC on mycelial growth and sporulation of A. alternata. Pseudomonas syringae was inhibited at 200 mg/L of CuNPs. CuNPs were not significantly biocidal against Rhizobium spp. and Trichoderma harzianum compared to CoC. Evaluation of the effect of CuNP on wheat revealed that rate of germination of wheat seeds was higher in presence of CuNPs and CoC compared to control. Germination vigor index, root length, shoot dry weight and seed metabolic efficiency of wheat were negatively affected. At low concentration, CuNPs promoted the growth of the plant pathogenic fungi Botrytis fabae, Fusarium oxysporum f.sp. ciceris, F.oxysporum f.sp. melonis, Alternaria alternate and P. syringae, and sporulation of T. harzianum. Synergistic effect of CuNPs and CoC in inhibiting P. cinnamomi offers a possibility of developing new fungicide formulation for better control of the oomycetes. Non-biocidal effect of CuNPs against beneficial microbes indicates its potential use in the agri-ecosystem.

Metal-loaded polyol-montmorillonite with improved affinity towards hydrogen

Metal-organoclays (MOC) were prepared through incorporation of Boltorn polyol dendrimer H30 in Na+-exchanged montmorillonite (NaMt), followed by in-situ dispersion of Cu0 and Pd0 nanoparticles (CuNPs and PdNPs). The organoclays displayed high CO2 retention capacity (CRC) of 3.6–11.1 μmol/g, but metal incorporation induced a significant increase of hydrogen uptake up to 51.8–508.2 micmol/g at the expense of the CRC. Thermal programmed desorption and FT-IR investigations revealed strong interactions with CO2 before metal incorporation. These interactions markedly depleted in the presence of CuNPs and PdNPs. This was regarded as a precise indicator of the appreciable metal stabilization within the organic entanglement, due to enhancements of HO:Cu0 and HO:Pd0 interactions at the expense of HO:CO2 carbonate-like association. The CO2 and H2 retention capacities (CRC and HRC, respectively) were found to strongly correlate to the number of OH groups of the dendritic moiety incorporated. Hydrogen retention appears to involve mainly physical interactions as supported by easy gas release between 20 °C and 75 °C or even at room temperature under vacuum. This demonstrates unequivocally the reversible capture of hydrogen. The increase of the hydrogen uptake with increasing contact time provides evidence of the occurrence of diffusion phenomena. This was not observed with CO2 before metal incorporation, suggesting a structure compaction that improves metal stabilization. This opens new prospects for hydrogen storage via truly reversible capture on low cost clay materials and biodegradable hyperbranched macromolecules deriving from plants.

Copper nanoparticles advance electron mobility of graphene-like boron nitride for enhanced aerobic oxidative desulfurization

Recently, graphene-like boron nitride (g-BN), has been developed a new application, as a catalyst for aerobic catalysis, which gives it a passport to catalytic field. However, its way to be a high-active one is blocked by its insulation property. In this work, copper nanoparticles (Cu NPs) with nano-size and low resistivity, are confined through g-BN (Cu NPs/g-BN) to boost electron mobility by a simple one-pot pathway. Experiments show that Cu NPs/g-BN hosts a better performance in aerobic oxidation of aromatic sulfur compounds with a catalytic activity of >97%. Cyclic voltammetry (CV) curves give a testimony that the presence of Cu NPs for raised electron mobility is a key element to the high catalytic activity. Besides, the catalyst can be recycled for 10 times without significant decrease in aerobic catalytic activity, which is found to be related with the idiosyncratic oxidation-resisting property of Cu NPs. Experiments find that the extraordinary oxidation-resisting property of Cu NPs mainly relates to the existence of g-BN, which can keep Cu NPs away from being oxidized. This work provides another sight for enlargement of application of g-BN for aerobic catalysis and a new strategy for preservation of NPs.

Doping graphene thin films with metallic nanoparticles: Experiment and theory

Precise doping of graphene at nanoscale resolution is vital for a number of applications in nanoelectronics and sustainable energy. Although large metallic contacts are presumed to move the Fermi level of graphene above or below the Dirac point, little has been done to study these effects when graphene is in contact with nanoscale metallic objects of specific sizes and concentrations and to investigate if such phenomena are associated with some forms of doping as in conventional semiconductors. As a case study we determine here the local effect of copper nanoparticles (Cu-NPs) on the Fermi energy of graphene domains in large-area graphene thin films. Tight-binding calculations corroborate our Kelvin-probe force microscopy experiments indicating that the Fermi level shifts in the presence of Cu-NPs (corresponding to 0.2 eV at 20% graphene area coverage by Cu) which break the electron-hole symmetry of graphene due to its weak Van der Waals interactions with Cu even in the absence of chemical bonding and charge transfer, in contrast to previous predictions for large and flat metallic contacts.

In situ formation of copper nanoparticles in a p(NIPAM-VAA-AAm) terpolymer microgel that retains the swelling behavior of microgels

Abstract Copper nanoparticles (CuNPs) are formed inside a microgel assembly by an in situ reduction method, confirmed by changes observed in the absorption spectra of CuNPs at different pH values. The presence of CuNPs has been also confirmed by X-ray diffraction (XRD) studies. The terpolymer microgel p(N-isopropylacrylamide-vinyl acetic acid-acrylamide) (p[NIPAM-VAA-AAm]), which is reported for the first time, was synthesized by free radical emulsion polymerization of a temperature-sensitive NIPAM monomer, pH sensitive VAA monomer and a hydrophilic AAm monomer. The effect of temperature below and above the pKa of VAA and the effect of pH at 20°C in the absence and presence of CuNPs on the hydrodynamic radius of microgel was studied. Size of microgel particles is a function of temperature due to the presence of NIPAM, and a function of pH due to the presence of VAA. The presence of CuNPs has little or no effect on the size of microgels by varying pH, which allows these gels to retain their properties with added benefits of CuNPs for possible drug delivery applications.