Hybrid composites containing Cu nanostructures (NSs), reduced graphene oxide (RGO), and polystyrene (PS) were produced for electromagnetic shielding application. First, Cu NSs including nanoparticles ...(NPs), nanorods (NRs), and nanowires (NWs) were prepared by a green method using eucalyptus bark extract from the reaction of copper(II) chloride in ethylene glycol (EG) at 186 °C. The FE-SEM images, XRD patterns, and Raman spectroscopy were used to characterize these NSs. The RGO/PS composite was prepared by introducing RGO to the PS matrix. The tensile test revealed that by adding 10% of RGO to the PS matrix, the tensile strength of the RGO/PS composite increased by 13.8%. The thermal properties of the RGO/PS composite indicated that with the uniform incorporation of RGO on the PS matrix, the thermal stability of the polymer composite was elevated to 350 °C and the Tg to 112 °C. Conductive polymer nanocomposites (PNCs) were prepared by adding Cu NSs to the RGO/PS composite. The results showed that these PNCs had electromagnetic interference (EMI) shielding; the shielding effectiveness of PNCs containing 10% RGO and 25% Cu NWs was 36.0 dB at 8.0 GHz and 29.5 dB at 12.0 GHz. The predominant mechanism of protection in the frequency range and percentages of the filler under study was of the reflection type.
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The Cu/RGO/PS polymer NCs have the ability of shielding against the interference of electromagnetic waves; so that the shielding effectiveness in the sample of polymer NCs containing 10 wt% of RGO and 25 wt% of Cu NWs were 36.0 dB at 8.0 GHz and 29.5 dB at 12.0 GHz.
•RGO & Cu NSs were prepared by a green method using eucalyptus bark extract.•Adding 10% RGO, the tensile strength of RGO/PS polymer composite increased by 13.8%.•Thermal stability and Tg of Cu/RGO/PS NCs increased to 350 and 112 °C, respectively.•Conductive polymer NCs was prepared by adding Cu NSs to RGO/PS polymer composite.•Shielding effectiveness of Cu/RGO/PS NCs were 36 dB at 8 GHz and 29.5 dB at 12.0 GHz.
For the efficient surface plasmon resonance (SPR)-based DNA assay researching, signal amplification tactics were absolutely necessary. In this work, a sensitive SPR-DNA sensor was developed by ...employing in situ synthesis of copper nanoparticles (CuNPs) templated by poly-T sequences DNA from terminal deoxynucleotidyl transferase (TdT)-mediated extension, and synergistically with nano-effect deposition as the mass relay. The objective of this strategy was manifold: firstly, tDNA hybridized with the optimal designed probes to active the TdT-mediated DNA extension onto the surface of SPR chip, resulted a long poly-T sequences ssDNA chain in dsDNA terminal onto surface of gold chip and characterized by SPR signal amplitudes. Secondly, copper ion (Cu2+) adsorbed into the skeleton of poly-T sequences DNA, with the aid of ascorbic acid (VC) to achieve the Cu2+ reduction, copper nanostructures (CuNPs) was synchronously generated onto the single nucleotide chain anchoring in dsDNA derivatives and the formation was featured by transmission electron micrographs (TEM) and electrochemistry. Lastly, dsDNA-complexed CuNPs (CuNPs@dsDNA) triggered the final signal amplification via real-time conversion of the additive catechol violet (CV) into oligomer or chelation precipitation by CuNPs-tagged reporters. With the proposed setups, a precise and replicable DNA sensing platform for specific target oligo was obtained with a detection limit down to 3.21 femtomolar, demonstrating a beneficial overlapping exploitation of nanomaterials and biochemical reaction as unique SPR infrastructure. Such triple-amplification strategic setups, the possibility of various methods abutment and biocompatibility weight reactor was amassed and adapted to more biological detection field.
•An ultrasensitive SPR sensor of femtomolar-level DNA detection was developed with triple-dual amplification.•CuNPs could be in situ synthesized with the templates of poly-T sequences in dsDNA origami individuals.•Catechol violet was selected as a real-time initiator for mass reply by labeled CuNPs@dsDNA.
Metallic copper and copper oxide thin films were fabricated on surface of glass slide substrates. Copper oxide thin films were prepared by a hydrothermal method using an α-phase layered hydroxide, ...copper hydroxide nitrate as a precursor. Morphology, thickness and crystallite size of the obtained copper oxide thin films changed by changing the time of hydrothermal treatment. Accordingly, the copper oxide thin films showed various water contact angles and optical band gaps. As, the optical band gap of the nanostructured copper oxide thin films increased with an increase in hydrothermal time from 1.85 to 2.95eV. Moreover, the water contact angles changed from 16.4 to 38.8° by changing the hydrothermal time. By a reductive hydrothermal-treatment route, the copper oxide thin film was reduced to metallic copper thin film without any particle growth.
SEM image of copper oxide thin film (inset shows its contact angle image of surface). Display omitted
•An α-phase layered hydroxide was used to produce copper oxide thin films.•Metallic copper thin film was also produced by a hydrothermal method.•Nano copper oxide thin films showed tunable band gap and wettability.
The intrinsic affinity of DNA molecules toward metallic ions can drive the specific formation of copper nanostructures within the nucleic acid helix structure in a sequence-dependent manner. The ...resultant nanostructures have interesting fluorescent and electrochemical properties, which are attractive for novel biosensing applications. However, the potential of using DNA-templated nano- structures for precision disease diagnosis remains unexplored. Particularly, DNA- templated nanostructures show high potential for the universal amplification-free detection of different RNA biomarker species. Because of their low cellular levels and differing species-dependent length and sequence features, simultaneous detection of different messenger RNAs, microRNAs, and long non-coding RNAs species with a single technique is challenging. Here, we report a contemporary technique for facile in situ assembly of DNA-templated copper nanoblocks （CuNBs） on various RNA species targets after hybridization-based magnetic isolation. Our approach circumvents the typical limitations associated with amplification and labeling procedures of current RNA assays. The synthesized CuNBs enabled amplification-free fM-level RNA detection with flexible fluorescence or electrochemical readouts. Furthermore, our nanosensing technique displays potential for clinical application, as demonstrated by non-invasive analysis of three diagnostic RNA biomarkers from a cohort of 10 prostate cancer patient urinary samples with 100%-concordance （quantitative reverse transcription- polymerase chain reaction （PCR） validation）. The good analytical performance and versatility of our method may be useful in both diagnostics and research fields.
Due to the low cost and plasmonic properties existence in the visible range of wavelengths, copper nanostructures are of great interest for Surface-enhanced Raman spectroscopy. In this paper we ...propose a method for synthesizing copper nanostructures by galvanic displacement into the pores of the ion-track SiO2/Si template. The copper deposit morphology grown in a limited volume of SiO2 pores on silicon is studied. The results of electron diffraction indicate that copper deposit contains oxides phases CuO and Cu2O. By using of x-ray photoelectron spectroscopy, chemical composition and elements bonds of SiO2(Cu)/Si system are studied in detail. The possibility of using such structures for Surface-enhanced Raman spectroscopy is discussed.
Abstract Hyperthermia is a cancer treatment strategy that involves raising the temperature of the afflicted tissues without disrupting the surrounding tissues. This study is focused on finite element ...analysis of copper, nanoellipsoids, nanorods, nanospheres and core-shells for potential hyperthermia application. The temperature of copper nanostructures was elevated using an external source to the desired temperature to destroy the cancerous cell. The COMSOL Multiphysics package was used to calculate how long it would take to achieve the desired temperature using different nanostructures of copper. Thermal sensitivity of the tested nanostructures was checked by putting them in a spherical domain of tissue. It was observed that copper nano-rod attained the highest temperature of 43.3 °C compared to other geometries. It was also found that these geometries attained thermal equilibrium just after 0.5 μ s. However, the copper nano-ellipsoid had a higher core volume, which is utilized to determine the thermal sensitivity of the nanostructures. Noble metal (Au) coating was first found to be better than PEG polymer coating for investigating core–shell structures. The Au coating on the surface of the copper core resulted in a gradual decrease in temperature with an increasing volume coverage ratio. These results conclude that copper nanostructures can be suitable candidates for hyperthermia.
In this study, null and one-dimensional nanoparticles and nanostructures of Ag and Ag-Cu were synthesized using polyol method. In order to prepare different nanostructures with the same synthesis ...route, thermodynamics and kinetic conditions of the system were manipulated. In the thermodynamics approach, the nanostructures with the minimum surface energy were obtained as the final product, while in kinetic approach, the nanostructures with the lower activation energy were formed. By using these appraoches, Ag and Ag-Cu spherical and cubical nanostructures were produced in the size range of 90-100 nm. Also, by manipulating the kinetic conditions of the system, silver nanowires with the diameters in the range of 100-200 nm and the length of several microns were obtained successfully. The effect of Cu ions (Cu2+) on aspect ratio of the synthesized silver nanowires by polyol method was evaluated.
Increasing heat dissipation requirements of small and miniature devices demands advanced cooling methods, such as application of immersion cooling via boiling heat transfer. In this study, ...functionalized copper surfaces for enhanced heat transfer are developed and evaluated. Samples are functionalized using a chemical oxidation treatment with subsequent hydrophobization of selected surfaces with a fluorinated silane. Pool boiling tests with water, water/1-butanol mixture with self-rewetting properties and a novel dielectric fluid with low GWP (Novec™ 649) are conducted to evaluate the boiling performance of individual surfaces. The results show that hydrophobized functionalized surfaces covered by microcavities with diameters between 40 nm and 2 µm exhibit increased heat transfer coefficient (HTC; enhancements up to 120%) and critical heat flux (CHF; enhancements up to 64%) values in comparison with the untreated reference surface, complemented by favorable fabrication repeatability. Positive surface stability is observed in contact with water, while both the self-rewetting fluids and Novec™ 649 gradually degrade the boiling performance and in some cases also the surface itself. The use of water/1-butanol mixtures in particular results in surface chemistry and morphology changes, as observed using SEM imaging and Raman spectroscopy. This seems to be neglected in the available literature and should be focused on in further studies.
Two alternative approaches to measuring the depth of nanoholes (nanopits) formed in metallic aluminum in the process of its high-voltage anodizing are proposed. The first approach consists of the ...electron microscopic study of a metallic layer section formed by cutting ions with the use of a sputtered protective platinum layer with immediate observation of an array of nanopits. The second (indirect) method consists of manufacturing copper replicas from a metallic aluminum layer with the further electrochemical measurement of the overall surface area of the copper electrode and the calculation of the height of the copper nanobristles. It is shown that both approaches lead to the same results.
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