Stabilized Copper Nanoparticles Research Articles

Novel short Agave americana based biocomposite and nanobiocomposites for automotive applications

Short fibers of Agave Americana (AA) was extracted from its plant leaf, was chemically treated with Ac2O, HCOOH, H2O2, KMnO4 and NaOH, and then characterized by Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), thermo-gravimetric/differential thermo-gravimetric (TGA/DTG), and field emission-scanning electron microscopy (FE-SEM). PVA stabilized copper nanoparticles from chemical reduction method was characterized using field emission-scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDAX), powder X-ray diffraction (PXRD), Dynamic light scattering analysis (DLS), UV–visible absorption spectroscopy, Fourier Transform infrared (FT-IR) spectroscopy and Thermogravimetric analysis/differential thermogravimetry (TGA/DTG). Bio-composites (AA + Polyester Resin (PE) and hybrid nano bio-composites (AA + Polyester Resin (PE) + Cu) were prepared from the untreated and treated AA fibers and further characterized. The synergistic effect of chemical treatment on morphological (SEM), thermal (TGA/DTG), mechanical properties (flexural, tensile, impact and compressive strength) followed by % water absorption were examined. The average surface roughness values (Ra) of chemical treated fiber was identified to be in decreasing manner along with compression strength of biocomposite in the order of untreated (10.74 μm, 44.01 MPa) > NaOH (8.55 μm, 45.07 MPa) > HCOOH (3.49 μm, 24.10 MPa) Ac2O (3.24 μm, 22.10 MPa) > H2O2 (2.51um, 17.9 MPa) > KMnO4 (1.52 μm, 15.1 MPa) treated fibers. Subsequently, the addition of 2s@PVA led to reverse the order namely, the compressive strength of the bionanocomposites were Untreated (10.74 μm, 9.0 MPa) < NaOH (8.55 μm, 0.1 MPa) < HCOOH (3.49 μm, 3.6 MPa) < Ac2O (3.24 μm, 7.6 MPa) < H2O2 (2.51um, 13.3 MPa) < KMnO4 (1.52 μm, 44.1 MPa) treated fibers. Similarly, the biocomposite where the fibres were treated with NaOH, HCOOH were more rough and had, good interconnection between fiber/PE matrix along with enhanced mechanical properties. On addition of nanobiocomposite, only KMnO4 treated fiber composite possed significant mechanical properties. Therefore, mixing CuNPs@PVA with KMnO4 treated fibers led to significant boost to the mechanical properties and minimised the % water absorption properties when compared to the untreated AA/PE biocomposites. The KMnO4 treatment of the AA fiber and addition of copper nanoparticles caused the enhancement of thermal properties, tensile strength and flexural strength. But, these nanobiocomposites were observed to have low impact strength; while, H2O2 treated nanobiocomposites had highest impact strength. The chemical treatment of the AA fiber with NaOH, Ac2O and KMnO4 developed the water resistance of the respective biocomposites. All the nanobiocomposites with chemically treated AA fibers (except Ac2O) were found to have high water resistance. So, they can be used in automotive industry for non-structural applications.

Sustainable Finished Leather Preservation

Part 1 of the current paper described the green synthesis of myrobalan capped copper nanoparticles for the preservation of the finished leather. In Part II of the current study, Copper Nanoparticles (CuNPs) were synthesized using green synthesis with wattle (tannin) extract as a reducing agent. Green synthesis is the preferred approach for the synthesis of metal nanoparticles due to its eco-friendly and cost-effectiveness for the preservation of finished leather. To improve the antibacterial qualities of leather with different types of finishes, the resin finished leather was coated with synthesized wattle copper nanoparticles (W-CuNPs). The chemical constituents of wattle induce the reduction of Cu2+ ions to CuNPs with the capping process and also remain as a stabilizing agent for the capping process. The formation of W-CuNPs was confirmed by UV-Spectroscopy at an absorbance of 467 nm. The identified functional groups such as -OH, C=C, and C-N were analyzed by Fourier transform infrared spectrum (FT-IR) which are responsible for the reduction and stabilization of copper nanoparticles. The spherical shape of the nanoparticles was ascertained by Scanning Electron Microscope (SEM), whereas Energy dispersive X-ray (EDX) studies confirmed the presence of copper with 65%. The average particle size of W-CuNPs was found to be 96 nm. The zeta potential value of -24 mv affirmed the stability of the W-CuNPs. The maximum zone of inhibition was 12 mm against Gram-positive (Bacillus subtilis) and 11 mm against Gram-negative (Serratia marcescens) bacteria on W-CuNPs coated finished leather, which exhibits strong antimicrobial activity. Hence, CuNPs synthesized by wattle extract have the potential to preserve the finished leather and its products as an antibacterial agent.

NHC stabilized copper nanoparticles via reduction of a copper NHC complex.

The bottom-up synthesis of plasmonic NHC@CuNPs from common starting reagents, via the formation of the synthetically accessible NHC-Cu(I)-Br complex and its reduction by NH3·BH3 is reported. The resulting NHC@CuNPs have been characterized in detail by XPS, TEM and NMR spectroscopy. The stability of NHC@CuNPs was investigated under both inert and ambient conditions using UV-Vis analysis. While the NHC@CuNPs are stable under inert conditions for an extended period of time, the NPs oxidize under air to form CuxO with concomitant release of the stabilizing NHC ligand.

Green adeptness in the synthesis and stabilization of copper nanoparticles using aqueous root extract of Schrebera swietenioides Roxb, and its catalytic application

The discovery of various advanced materials that are applicable in remediation of environment pollutants was rapidly advancing because of their applications in wide range. Green synthesized Nano particles (NPs) were currently gaining attention in photodegradation of dyes and metals due to its ecofriendly, cost effective and simple production. Hence this study intended to synthesize and characterize the nano sized copper particles using aqueous root extract of Schrebera swietenioides Roxb., as green reducing agent. The synthesized NPs were characterized and proved that the NPs were aggregates with spherical shape to undefined shapes with an average particle size of 32±4 nm and contain 82.5 % of copper metal in the particles. Further, the synthesized NPs were applied for the removal of Sudan red (III) dye, Azure A dye and Lead metal. The findings proved that the NPs had potential degradation efficacy on the degradation of Sudan dye, Azure A dye and Lead metal. The NPs were durable and could be reusable with high degradation efficacy after three cycles of study for both dyes and metal in the study. Therefore, the green synthesized Cu NPs are potential candidates for photocatalytic applications. Keywords: Copper nano particles, Photo catalytic activity, Azure A dye, Lead metal degradation.

Green synthesis, characterization, and application of copper nanoparticles obtained from printed circuit boards to degrade mining surfactant by Fenton process

The disposal of solid waste containing toxic metals in the composition is a problem of environmental and human contamination. The amount of waste as printed circuit boards has been increasing year by year. New processes that aim at recycling and subsequent application implementing a circular economy of this waste have been gaining importance. This study proposes the printed circuit boards characterization for the copper recycling by acid leaching in two steps, green synthesis of copper nanoparticles using ascorbic acid (vitamin C), and later application of nanoparticles into surfactant degradation through the Fenton-like process. Acid leaching proved a possible methodology for recycling copper, obtaining over 90% recovery. The printed circuit boards show to be a copper secondary source with a weight percentage of about 26 and recovery of 97% in two leaching stages. The synthesis of CuNPs was inferred through UV–Vis with absorption peak in 585 nm and modification of the coloration over time of solutions to dark brown. The syntheses were performed at 70 °C, 80 °C, and 90 °C and in 0.17, 0.5, 0.83, 1, 2, and 3 h, and the stability of copper nanoparticles was verified in 168, 720, and 960 h after syntheses. Stable nanoparticles were produced with different diameters, and they were applied as a catalyst in the Fenton reaction to degrade an amine-based surfactant used in the mining industry. The total carbon degradation found was 57%. It was possible to observe that the recycling of printed circuit boards is strategic to obtain copper from a secondary source, and the synthesis of copper nanoparticles could be used as a product to applicate in the circular economy using the Fenton process.

Spectrophotometric and fluorometric detection of DNA/BSA interaction, antimicrobial, anticancer, antioxidant and catalytic activities of biologically active methoxy substituted pyrimidine-ligand capped copper nanoparticles

New Schiff base ligand (DPMN) was synthesized from the condensation of 2-hydroxy-5-nitrobenzaldehyde and 2-amino-4,6-dimethoxypyrimidine which was confirmed by spectroscopic and analytical methods. Solid air stable copper nanoparticles (DPMN-CuNPs) were synthesized from its copper chloride salt and it is stabilized by the prepared Schiff base ligand by phase transfer assisted synthesis which is a modified Brust-Schiffrin technique. The formation of ligand stabilized copper nanoparticles was confirmed by UV–Visible and FT-IR spectroscopic techniques. The size, surface morphology and quality of DPMN-CuNPs were analyzed by SEM and TEM techniques. Antioxidant activities of DPMN and DPMN-CuNPs with DPPH, SOD, peroxide and nitrous oxide were analyzed by electronic absorption spectroscopy. DNA interaction between DPMN and DPMN-CuNPs with CT-DNA was carried out using electronic absorption, fluorescence, viscometric measurements and cyclic voltammetric techniques. Interaction between BSA and the synthesized compounds analyzed by electronic absorption spectroscopy, Antimicrobial studies confirmed that the synthesized DPMN-CuNPs possess significant biological activities than DPMN. Anticancer results suggest that prepared DPMN-CuNPs have significant anticancer activity against different cancer cell lines and least toxic effect against the normal (NHDF) cell line. Other than the positive response in biological evaluation, our DPMN-CuNPs possess good catalytic activity in methyl orange reduction, methylene blue degradation and nitro phenol reduction.

Preparation and study of the physicochemical characteristics of multilayer polymer composites based on poly(ethyleneimine)-stabilized copper nanoparticles and poly(sodium 2-acrylamide-2-methyl-1-propanesulfonate)

Multilayer films were synthesized from a complex of branched polyethyleneimine (PEI) with copper nanoparticles (PEI-CuNPs) and sodium poly-2-acrylamide-2-methyl-1-propanesulfonate (PAMPSNa), applied layer-by-layer (LbL) on a solid support in an acidic medium. Protonation of the amino groups of PEI in an acidic medium increases the positive charge of the PEI-CuNPs system to +43.5 mV and promotes the formation of an interpolyelectrolyte complex between the positively charged PEI-CuNPs and the highly charged anionic polyelectrolyte PAMPS, the ζ-potential of which was -141 mV. AFM images and SEM micrographs showed a uniform distribution of spherical copper nanoparticles in the homogeneous structure of the multilayer film. The optical characteristics and hydrodynamic dimensions of PEI-CuNPs indicate the formation of PEI-CuNPs nanoparticles with sizes of 60-300 nm, with an average size of up to 100 nm. Copper nanoparticles distributed uniformly in a multilayer PEI-CuNPs/PAMPS film may be of interest for applications in the field of membrane catalysis, biochips, sensor membranes, and controlled drug delivery.

A zero-background fluorescent aptasensor for ultrasensitive detection of pesticides based on magnetic three-dimensional DNA walker and poly(T) -templated copper nanoparticles

A zero-background fluorescent aptasensor for the ultrasensitive detection of pesticides has been successfully constructed, using poly(T) stabilized copper nanoparticles (CuNPs) as a fluorescent signal and three-dimensional (3-D) DNA walker as a signal amplifier. To fabricate the aptasensor, one strand of dsDNA and one strand of ssDNA are immobilized onto magnetic Fe2O3 beads. The dsDNA is hybridized by the target aptamer contained DNA (Apt-1) and the partial complementary DNA which named as WS since it acts as a walking strand (WS) in DNA walker. Upon the specific binding between omethoate with Apt-1, WS becomes a free walking ssDNA strand. With the aid of nicking endonuclease, the 3-D DNA walker can produce a great quantity of poly(T) DNA during the WS walking. When the supernatant is added into ascorbic acid (AA) and Cu2+, poly(T) templated CuNPs forms and strong fluorescence generates. The developed aptasensor has a zero-background, and can ultrasensitively detect omethoate in the linear range of 0–200 nM with the detection limit of 0.22 nM. This zero-background aptasensor provides a facile strategy for pesticides determination in the fields of food safety and environmental monitoring.

Facile microwave-mediated green synthesis of non-toxic copper nanoparticles using Citrus sinensis aqueous fruit extract and their antibacterial potentials

This study focuses on the utilization of orange (Citrus sinensis) fruit extract for microwave mediated green synthesis of copper nanoparticles for the first time. After completion of the synthesis cycles, the presence of a maximum peak at the wavelength of 560 nm by UV–vis spectroscopy indicated the formation of CuNPs. FTIR spectrum identified the functional biomolecules of the orange juice extract, responsible for the bioreduction, stabilization of copper nanoparticles. Scanning Electron Microscopy (SEM) indicated the presence of globular shaped nano-sized copper particles with smooth surfaces whereas Energy Dispersive X-ray Spectrometry (EDX) confirmed the presence of copper, carbon and oxygen atoms with the amount of 77.68%, 17.55% and 4.77%, respectively. Transmission Electron Microscopy (TEM) illustrated that the CuNPs are morphologically round in shape with the distribution range of 6.93 nm–20.70 nm in diameter. X-ray diffraction (XRD) analysis revealed the presence of face-centered cubic crystalline structures of copper nanoparticle, and Zeta potential analysis confirmed their high stability by showing the strong negative potential value (−25.60 mV). Moreover, these biosynthesized copper nanoparticles displayed their efficiency in controlling the growth of the bacteria, i.e., Escherichia coli and Staphylococcus aureus. The results revealed their non-cytotoxic nature on the L929 mouse fibroblast cell line through XTT cell viability assay. All these studies indicated that CuNPs synthesized by orange extract have the potential to serve as a green nanomaterial for biomedical applications.

Sophie Carenco

Sophie Carenco

Synthesis of methoxy substituted pyrimidine derivative imine stabilized copper nanoparticles in organic phase and its biological evaluation

Methoxy substituted pyrimidine derivative Schiff base ligand (DMPMM) and its stabilized copper nanoparticles (DMPMM-CuNPs) were synthesized by modified Brust-Schiffrin technique. The formations of DMPMM and DMPMM-CuNPs were proved by UV–Visible and FT-IR spectroscopic studies. The size, surface morphology and the quality of DMPMM and its MNPs were analyzed by Scanning Electron Microscopy (SEM) technique. Transmission Electron Microscopy (TEM) result shows that DMPMM-CuNPs has approximately 3 to 5 nm size. Electrochemical performance of the DMPMM-CuNPs was analyzed by cyclic voltammetric method. DNA binding studies of the DMPMM and DMPMM-CuNPs with CT-DNA were inspected by four different methods such as UV–Visible, emission spectroscopy, cyclic voltammetry and viscometric measurements. Spectroscopic, voltammetric, viscometric and denaturation (Thermal and sono-chemical) studies results recommend the synthesized compounds have good DNA binding ability. The four different antioxidant scavenging studies results shows that DMPMM and DMPMM-CuNPs have significant antioxidant activity. Antimicrobial studies of the DMPMM and DMPMM-CuNPs were studied by well diffusion method. Anticancer studies results evidenced that the synthesized DMPMM-CuNPs have good selectivity to interact with human cancer cells and normal cell correspondingly. DMPMM-CuNPs destroy the normal cell line at higher concentration (84.3 μg/mL). This observation decides that the synthesized DMPMM-CuNPs has good anticancer activity. • Solid and stable copper nanoparticles were successfully prepared. • The size of the prepared copper nanoparticles was approximately 3 to 5 nm. • Prepared copper nanoparticles were soluble in most of the organic solvents. • Copper nanoparticles have good biological properties especially in anticancer studies.

Bio-Synthesis of copper nanoparticles (CuNPs) using Garlic extract to investigate antibacterial activity

Bio-synthesis of metal nanoparticles (CuNPs) is regarded as one of the recently developed, economic and environmentally benign method. In the present investigation, Copper nanoparticles were synthesized reacting garlic (Allium sativum) extract with Copper Sulphate (CuSO4∙5H2O) solution over magnetic stirrer at 80 °C for 1 hour. So-prepared CuNPs were studied by observing the color change at various time intervals. Further, the nanoparticles were characterized using UV-Visible spectroscopy, Energy Dispersive X-ray spectroscopy (EDX) and Fourier Transform Infrared spectroscopy (FTIR). The results of UV-Vis spectroscopy clearly showed presence of absorption peak at 595 nm which confirmed the formation of copper nanoparticles. Likewise, the EDX spectrum depicts the presence of optical band at 8 eV which is the characteristic peak of Copper consisting of 38.747 % by weight and FTIR spectra revealed presence of various phytochemicals possessing characteristic functional groups such as carbonyl and phenolic at the surface of CuNPs. Thus, natural products available in the garlic extract help in reduction and stabilization of Copper nanoparticles. The antibacterial activity of Copper nanoparticles was investigated against Gram +ve (Staphylococcus aureus) and Gram –ve bacteria (Escherichia coli) using Agarwell diffusion method. The results of antibacterial test showed that CuNPs were found to be much sensitive towards Gram –ve bacteria compared to gram +ve bacteria.&#x0D; BIBECHANA 17 (2020) 12-18&#x0D; &#x0D;

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.

Utilization of Nanosized Carbamoylethyl Cellulose in Preparation of Copper Nanoparticles

Currently, much attention is paid to the development of efficient green materials derived from renewable resources characterized by biodegradability and non-toxicity to neither human nor environment. In this study, nano-carbamoylethyl cellulose (NCEC) with D.S. of 0.8 and size of ca 37nm was harnessed for preparation and stabilization of copper nanoparticles (CuNPs). To achieve the goal, NCEC acted as stabilizing agent during the synthesis of CuNPs. Indeed, CuNPs were produced in spherical shape with small sizes in range of 25 nm as signified by UV-vis spectroscopy and TEM. Nevertheless, the colloidal solutions of CuNPs at different concentrations exhibited extremely high stability.

Synthesis of graphene quantum dots stabilized CuNPs and their applications in CuAAC reaction and 4-nitrophenol reduction

Here we report the synthesis of graphene quantum dots (GQDs) stabilized copper nanoparticles in neat water. Construction of six CuNPs 1–6 nanocomposites are accomplished by mixing GQDs and NaBH4, and followed by the addition of different amounts of copper sulfate at 0 ℃ in water, respectively. Among them, CuNP-3, with the size of 2.6 nm, exhibits excellent catalytic performance in the CuAAC reaction over than other CuNPs. Moreover, the CuNP-3 has also been successfully applied for the reduction of 4-nitrophenol with excellent catalytic activity.

Microwave Assisted Synthesis and Carboxymethyl Cellulose Stabilized Copper Nanoparticles on Bacterial Cellulose Nanofibers Support for Pollutants Degradation

Bacterial cellulose (BC), a green biopolymer synthesized by certain bacteria, has been widely used for supporting different metal or their oxide nanoparticles which were utilized for different purposes. In this article, we report on using BC as a support for transition metal nanoparticles for catalysis purpose of organic pollutants. BC was synthesized using Gluconacetobacter xylinum. Then the copper (Cu) nanoparticles were synthesized by a quick procedure of microwave heating of the CuSO4 and hydrazine mixed aqueous solution in the presence of carboxymethyl cellulose (CMC). Typically, 10 μL suspension of the CMC stabilized Cu nanoparticles was coated on the BC nanofibers (CMC-Cu-BC) and further used for the catalytic reductions of methylene blue, 4-nitrophenol and in their mixed solution by sodium borohydride. All the samples were also characterized by X-ray diffraction, thermogravimetric analysis, and field emission scanning electron microscope. Our finding suggests that supported Cu nanoparticles catalyst performance was slower than its suspension. However, the ease of separation of the supported CMC-Cu-BC was appealing to be used.

Direct Synthesis of N‐Heterocyclic Carbene‐Stabilized Copper Nanoparticles from an N‐Heterocyclic Carbene–Borane

N-Heterocyclic carbene (NHC)-stabilized copper nanoparticles (NPs) were synthesized from an NHC-borane adduct and mesitylcopper(I) under thermal conditions (refluxing toluene for 2.5 h). NPs with a size distribution of 11.6±1.8 nm were obtained. The interaction between Cu NPs and NHC ligands was probed by X-ray photoelectron spectroscopy, which showed covalent binding of the NHC to the surface of the NPs. Mechanistic studies suggested that NHC-borane plays two roles: contributing to the reduction of [CuMes]2 to release Cu0 species and providing NHC ligands to stabilize the copper NPs.

Vitamin B1 Sensor at Neutral pH and Improvement by Cucurbit[7]uril

Abstract Thiamine deficiency is an important issue for many diseases and thus a facile method of detection is clinically important to improve the health of humans. For that purpose, we have developed a new thiamine sensor using starch stabilized copper nanoparticles (CSNP) at neutral pH and also improved the sensitivity of the sensor using cucurbit[7]uril (CB[7]) through host-guest chemistry. Often thiamine is not detected directly, but through the oxidation of thiamine to thiochrome (TC); TC is a fluorescent emitting molecule, through which thiamine has been measured indirectly. Here, we have demonstrated a new approach for a thiamine sensor, based on the formation of TC by the addition of hydrogen peroxide and CSNP. Unlike the other reported thiamine sensors, our method works advantageously at physiological pH conditions (pH 7, 27 °C). Furthermore, addition of CB[7] to TC, increased the sensitivity of the sensor approximately one order magnitude, through encapsulation; which can be reversed upon addition of a stronger competitive guest such as adamantylamine to confirm the encapsulation of TC. Thus, this new thiamine sensor not only performed well under physiological pH conditions, but also improved the fluorescence of TC, when encapsulated by CB[7].

The Influence of Polyelectrolytes on the Properties of Ultramicron and Nanosized Powders of Copper

This paper describes the results of studies on the synthesis and functionalization of the surface of nanoscale and ultradispersed copper powders in the production process. The principles of deagglomeration and specific problems for Nanoparticles are considered. The paper presents data on stabilization of copper nanoparticles in the process of obtaining, highlights the problems that require a good understanding, namely the study of the behavior of different types of ultra and nanoscale copper powders in the processes related to production of polymeric composite materials.

Nitrogen-doped graphene stabilized copper nanoparticles for Huisgen [3+2] cycloaddition "click" chemistry.

Nitrogen-doped reduced graphene oxide (NRGO) stabilized copper nanoparticles are designed to assist Cu(i)-catalyzed Huisgen [3+2] cycloaddition "click" chemistry (CuAAC). This study demonstrates a robust route for the synthesis of vastly dispersed heterogeneous catalysts (NRGO/Cu2O), achieving CuAAC at low temperature without any external additive (oxidizing/reducing agent) with high stability and recyclability. Underlying mechanisms are analysed using DFT calculations, confirming the experimental results.