The distributed Bragg reflectors (DBRs) consisting of alternating layers of ZnO and heavy doped amorphous silicon (a-Si) have been fabricated by magnetron sputtering. It is novel to find that the optical absorptions exist in the stopband of the DBRs, and that many discrete strong optical absorption peaks exist in the wavelength range of visible to near-infrared. The calculated results by FDTD show that the absorptions in the stopband mainly exist in the first a-Si layer, and that the light absorbed by other a-Si layers inside contributes to the two absorption peaks in near-infrared range. The strong absorptions ranged from visible to infrared open new possibilities to the enhancement of the performance of amorphous silicon solar cells.
In this work, the Stöber process was applied to produce uniform silica nanoparticles (SNPs) in the meso-scale size range. The novel aspect of this work was to control the produced silica particle size by only varying the volume of the solvent ethanol used, whilst fixing the other reaction conditions. Using this one-step Stöber-based solvent varying (SV) method, seven batches of SNPs with target diameters ranging from 70 to 400 nm were repeatedly reproduced, and the size distribution in terms of the polydispersity index (PDI) was well maintained (within 0.1). An exponential equation was used to fit the relationship between the particle diameter and ethanol volume. This equation allows the prediction of the amount of ethanol required in order to produce particles of any target diameter within this size range. In addition, it was found that the reaction was completed in approximately 2 h for all batches regardless of the volume of ethanol. Structurally coloured artificial opal photonic crystals (PCs) were fabricated from the prepared SNPs by self-assembly under gravity sedimentation.
New self-assembled material (Ru@SC) with ruthenium nanoparticles (Ru NPs) and 4-sulfocalix[4]arene (SC) is synthesized in water at room temperature. Ru@SC is characterized by thermal gravimetric analysis, FT-IR, powder x-ray diffraction, TEM and SEM analysis. The size of Ru nanoparticles in the self-assembly is approximately 5 nm. The self-assembled material Ru@SC shows an efficient catalytic reduction of toxic ‘brilliant yellow’ (BY) azo dye. The reduced amine products were successfully separated and confirmed by single-crystal XRD, NMR and UV-Vis spectroscopy. Ru@SC showed a better catalytic activity in comparison with commercial catalysts Ru/C (ruthenium on charcoal 5 %) and Pd/C (palladium on charcoal 5 and 10 %). The catalyst also showed a promising recyclability and heterogeneous nature as a catalyst for reduction of ‘BY’ azo dye.
An easy and rapid one-pot microwave-assisted soft-template synthesis method for the preparation of Pd-Ni nanoalloys confined in mesoporous carbon is reported. This approach allows the formation of mesoporous carbon and the growth of the particles at the same time, under short microwave irradiation (4 h) compared to the several days spent for the classical approach. In addition, the synthesis steps are diminished and no thermopolymerization step or reduction treatment being required. The influence of the Pd-Ni composition on the particle size and on the carbon characteristics was investigated. Pd-Ni solid solutions in the whole composition range could be obtained, and the metallic composition proved to have an important effect on the nanoparticle size but low influence on carbon textural properties. Small and uniformly distributed nanoparticles were confined in mesoporous carbon with uniform pore size distribution, and dependence between the nanoparticle size and the nanoalloy composition was observed, i.e., increase of the particle size with increasing the Ni content (from 5 to 14 nm). The magnetic properties of the materials showed a strong nanoparticle size and/or composition effect. The blocking temperature of Pd-Ni nanoalloys increases with the increase of Ni amount and therefore of particle size. The magnetization values are smaller than the bulk counterpart particularly for the Ni-rich compositions due to the formed graphitic shells surrounding the particles inducing a dead magnetic layer.
Graphical abstract PdNi nanoalloys confined in mesoporous carbon exhibiting magnetic properties dependent on thealloys composition and size were synthesized by a fast microwave approach
Layered zinc-based metal-organic framework ([Zn(4,4′-bpy)(tfbdc)(H2O)2], Zn-LMOF) nanosheets were synthesized by a facile hydrothermal method (4,4′-bpy = 4,4′-bipyridine, H2tfbdc = tetrafluoroterephthalic acid). The materials were characterized by IR spectrum, elemental analysis, thermogravimetric analysis, powder X-ray diffraction, transmission electron microscope (TEM), scanning electron microscope (SEM), and the Brunauer–Emmett–Teller (BET) surface. When the Zn-LMOF nanosheets with the thickness of about 24 ± 8 nm were used as an anode material of lithium-ion batteries, not only the Zn-LMOF electrode shows a high reversible capacity, retaining 623 mAh g?1 after 100 cycles at a current density of 50 mA g?1 but also exhibits an excellent cyclic stability and a higher rate performance.
Graphical abstract Zinc-based layered metal-organic framework ([Zn(4,4′-bpy)(tfbdc)(H2O)2], Zn-LMOF) nanosheets have been synthesized, displaying a high capacity as anode materials for lithium-ion batteries.
We report a novel method for formation of self-organized single-standing carbon nanotubes by customizing a plasma-based process. The growth of carbon nanotubes by plasma-enhanced chemical vapor deposition provides suitable grounds to utilize plasma–solid interactions for nanopatterning. The bulk plasma is utilized to fabricate carbon nanotubes on the prepatterned Ni catalyst which in turn can confine the plasma to the growth region. The plasma localization leads to a dielectrophoretic force exerted on Ni atoms and can be engineered in order to grow a specific pattern of self-organized single-standing carbon nanotubes. Numerical simulations based on the plasma localization and dielectrophoretic force confirmed the experimental results. This method provides a simple and cost-effective approach to obtain nanopatterned arrays of carbon nanotubes which can be used for fabrication of photonic and phononic crystals, self-gated field emission-based transistors and displays.
Carbon-based nanoparticles (NPs) such as fullerenes and nanotubes have been extensively studied for drug delivery in recent years. The permeation process of fullerene and its derivative molecules through membrane is essential to the utilization of fullerene-based drug delivery system, but the mechanism and the dynamics of permeation through cell membrane are still unclear. In this study, coarse-grained molecular dynamics simulations were performed to investigate the permeation process of functionalized fullerene molecules (ca. 0.72 nm) through the membrane. Our results show that single functionalized fullerene molecule in such nanoscale could permeate the lipid membrane in micro-second time scale. Pristine C60 molecules prefer to aggregate into several small clusters while C60OH15 molecules could aggregate into one big cluster to permeate through the lipid membrane. After permeation of C60 or its derivatives into membrane, all C60 and C60OH15 molecules disaggregated and monodispersed in the lipid membrane.
For safety and environmental risk assessments of nanomaterials (NMs) and to provide essential toxicity data, nano-specific toxicities, or excess toxicities, of ZnO, CuO, and Ag nanoparticles (NPs) (20, 20, and 30 nm, respectively) to Escherichia coli and Saccharomyces cerevisiae in short-term (6 h) and long-term (48 h) bioassays were quantified based on a toxic ratio. ZnO NPs exhibited no nano-specific toxicities, reflecting similar toxicities as ZnO bulk particles (BPs) (as well as zinc salt). However, CuO and Ag NPs yielded distinctly nano-specific toxicities when compared with their BPs. According to their nano-specific toxicities, the capability of these NPs in eliciting hazardous effects on humans and the environment was as follows: CuO > Ag > ZnO NPs. Moreover, long-term bioassays were more sensitive to nano-specific toxicity than short-term bioassays. Overall, nano-specific toxicity is a meaningful measurement to evaluate the environmental risk of NPs. The log Teparticle value is a useful parameter for quantifying NP nano-specific toxicity and enabling comparisons of international toxicological data. Furthermore, this value could be used to determine the environmental risk of NPs.
Nitrilimine cycloadditions to ethylenes, acetylenes, and activated nitriles have been exploited in the presence of catalytic amounts of oleic-acid-coated iron oxide nanoparticles (diameter?=?11.9?±?1.0 nm). The reactions were fully regioselective with monosubstituted ethylenes and ethyl cyanoformiate, while mixtures of cycloadducts were obtained in the presence of methyl propiolate. The intervention of iron oxide nanoparticles allowed carrying out the cycloadditions at milder conditions compared to the metal-free thermal processes. A labile intermediate has been proposed to explain this behavior.
Graphical abstract Nitrilimine cycloadditions to ethylenes, acetylenes, and activated nitriles have been exploited in the presence of catalytic amounts of oleic-acid-coated iron oxide nanoparticles.
The effect of interaction of low-index atomic planes, (100), (110), and (111) terminating CdSe platelet nanocrystals is examined using molecular dynamics (MD) simulations. Asymmetry of the environment of atoms at the end surface layers leads to anisotropic deformation of the cubic lattice and to a relative shift of Cd and Se sub-lattices. Interference of distortions of the crystal lattice originating at the terminal surfaces leads to changes of symmetry of the CdSe lattice in the whole sample volume. In the models, 2–3 nm thick, for all types of surfaces under examination, the initial cubic lattice symmetry gets lost in the whole sample volume.
The mesoporous biosilica with unique 3D hierarchy in/organic functional groups is attractive material in terms of interfacial phenomena, and its high biocompatibility accelerates development in biomedical devices. In addition, their benefits also play a fundamental role in antimicrobial assessment. We hypothesize that the Diadesmis gallica biosilica surface acts as a biotemplate for AgCl and Au nanoparticle (NP) biosynthesis. Moreover, it exhibits antibacterial action human pathogenic bacteria. Nanoparticle biosynthesis was performed via a pure environmental-friendly, static, bottom-up in vitro regime. Minimal inhibitory concentrations evaluated systems with bionanocomposites for antibacterial efficiency in temporal time-dose-dependency. TEM and XRD depicts a biosilica “local sphere” which affects formation, stabilization and encapsulation of crystalline Au (9–27 nm) and AgCl (3–51 nm) NPs in one simple step. FTIR analysis reveals various functional in/organic groups, including Si–OH and polyamides. While both metal-bionanoparticles have analogical spherical shape with determined aggregation, ICP-AES analysis determined more effective 5.29 wt% Au NP formation than 1 wt% AgCl NPs. MIC analysis confirms that bionanocomposite with AgCl by concentration 0.014 mg/mL has the most effective antibacterial system for gram-positive and gram-negative bacteria strains. Although dual effect of Au/AgCl NP bionanocomposite has almost analogical influence on gram-positive bacteria, the synergic-antagonistic effect is irrelevant in this instance.
The most important limitation for boron neutron capture therapy of cancer is the selective accumulation of boron compounds in tumor tissues in significant quantities. In this paper, we describe the possibility to use magnetic Ni/Fe nanotubes as carriers for boron delivery. Carborane derivatives containing 10 and 21 boron atoms per molecule were immobilized on Ni/Fe nanotubes by covalent and ionic interactions. Magnetic properties of NTs were investigated by Mössbauer spectroscopy. Structure, element, chemical composition, and morphology of obtained magnetic nanotubes were studied by XRD, SEM-EDA, and FTIR spectroscopy. Results indicate success immobilization of carborane derivatives on Ni/Fe nanotubes and great potential to use them as carriers for boron neutron cancer therapy of cancer.
Dendritic Pt–Cu nanoparticles were synthesized by a facile one-step method with the help of surfactant Brij58 at room temperature, and we also studied the effects of different Pt–Cu ratios on the morphology and size of nanoparticles. In addition, we further tuned the morphology of the Pt–Cu nanostructures by introducing bromide ions, eventually leading to the appearance of some tripod-like structures. Compared with dendritic Pt–Cu and commercial Pt black, these tripod-like Pt–Cu nanostructures exhibited higher electrocatalytic activity and CO tolerance for catalyzing methanol oxidation.
Addition reaction between C60 and ethylenediamine occurred at room temperature in an ambient condition. C60-ethylenediamine adduct particles were prepared by mixing toluene solutions of C60 and ethyelenediamine. Average diameter of the C60-ethylenediamine adduct particles was changed non-linearly according to the reaction time, which were observed using transmission electron microscopy. Early stage of the reaction, the diameter of the adduct particles was changed from about 250 to about 430 nm. Then, the size of the adduct particles was converged to about 300 nm. During this addition reaction, the crystalline sizes of adduct particles were constant about 2–3 nm, regardless of the sizes of the adduct particles, which were determined by X-ray diffraction measurement.
In this paper, the green synthesis of fluorescent carbon dots (CDs) via one-step hydrothermal treatment of cornstalk was investigated. This approach is facile, economical, and effective. The obtained CDs with an average diameter of 5.2 nm possess many excellent properties such as emitting blue fluorescence under UV light (365 nm), high monodispersity, good stability, excellent water dispersibility, and absolute quantum yield of 7.6%. Then, these CDs were used as sensing probes for the detection of Fe2+ and H2O2 with detection limits as low as 0.18 and 0.21 μM, respectively. This sensing platform shows advantages such as high selectivity, good precision, rapid operation, and avoiding the precipitation of iron oxyhydroxides.
A feasible in operation, labor-saving and low-cost one-step technology to fabricate fullerenol nanoparticles (FNPs) up to 10 g in laboratory was developed by improved alkaline-oxidation approach using moderately concentrated sodium hydroxide solution as the hydroxylation agent and o-dichlorobenzene as the solvent. This strategy paves the avenue for industrial-scale bulk production of FNPs. The resulted product, [C60(OH)22·8H2O]n, were characterized by various measurements including matrix-assisted laser desorption ionization time-of-flight mass spectrometry, high-resolution 1H nuclear magnetic resonance spectrometry, Fourier transform infrared spectroscopy, UV-Visible spectrophotometer, thermogravimetric analysis, differential scanning calorimetry, dynamic light scattering analysis, scanning electron microscopy, and electron spin resonance spectrometer. Radical scavenging assay in vitro confirmed the high efficiency of water-soluble [C60(OH)22·8H2O]n as a novel radical scavenger. Furthermore, [C60(OH)22·8H2O]n as an excellent candidate has the potential to serve as the plant defense stimulation agent in maize.
Bismuth ferrite, Fenton-like catalysts have been successfully synthesized via simple hydrothermal methods without any templates. Through changing the molar ratio of Bi/Fe, the two main phases BiFeO3 and Bi25FeO40 can be synthesized under different temperatures. Furthermore, different morphologies of the BiFeO3 phase can be adjusted by changing different concentrations of HNO3 and NaOH which were used to dissolve the reactants and adjust the pH values in the prepared process. When the concentration of HNO3/NaOH was 8/12 M, some uniform cylindrical bodies with equal height (1 μm) and width (0.6 μm) were obtained, which have not been reported before. The uniform structures exhibited better activities in the photoassisted Fenton-like oxidation process for the degradation of rhodamine B (RhB) under visible light irradiation (420 nm < λ < 800 nm). Through the detection of the degradation mechanism, it showed that the concerted effect of the catalysts and H2O2 can increase the generation of the charge carriers and accelerate the photogenerated charge transfer between the catalysts and dyes. The BiFeO3 samples also showed magnetic properties at room temperature, which may have potential applications in multiferroic or magnetoelectric sensors and devices.
Water dispersible boron nanoparticles have great potential as materials for boron neutron capture therapy of cancer and magnetic resonance imaging, if they are prepared on a large scale with uniform size and shape and hydrophilic modifiable surface. We report the first method to prepare spherical, monodisperse, water dispersible boron core silica shell nanoparticles (B@SiO2 NPs) suitable for aforementioned biomedical applications. In this method, 40 nm elemental boron nanoparticles, easily prepared by mechanical milling and carrying 10-undecenoic acid surface ligands, are hydrosilylated using triethoxysilane, followed by base-catalyzed hydrolysis of tetraethoxysilane, which forms a 10-nm silica shell around the boron core. This simple two-step process converts irregularly shaped hydrophobic boron particles into the spherically shaped uniform nanoparticles. The B@SiO2 NPs are dispersible in water and the silica shell surface can be modified with primary amines that allow for the attachment of a fluorophore and, potentially, of targeting moieties.
Catalytic systems designated for preferential oxidation of CO in the presence of H2 are prepared by ball milling of Cu and CeO2, a simple and cheap one-step process to synthesize such catalysts. It is found that after 60 min of milling, a mixture of 8 wt.% Cu–CeO2 powders exhibits CO conversion of 96% and CO selectivity of about 65% at 438 K. Two active oxygen states, which are not observed in case of pure CeO2, were detected in the nanocomposite lattice and attributed to the presence of Cu in surface sites as well as in subsurface bulk sites. Correspondingly, oxidation of CO to CO2 was found to occur in a two-stage process with Tmax ≈ 395/460 K, and oxidation of H2 to H2O likewise in a two-stage process with Tmax ≈ 465/490 K. The milled powder consists of CeO2 crystallites sized 8–10 nm agglomerated to somewhat larger aggregates, with Cu dispersed on the surface of the CeO2 crystallites, and to a lesser extent present as Cu2O.
Despite advancements in treatment of infectious diseases, opportunistic pathogens continue to pose a worldwide threat. Identifying a source of infection/inflammation is often challenging which highlights the need of improved diagnostic agents. Using a model of local S. aureus infection, here we evaluated the potential of betamethasone or dexamethasone loaded in poly (lactic acid) nanoparticles and radiolabeled with 99mTc to detect an infection/inflammation site in vivo. A betamethasone and dexamethasone nanoparticles (NPs) with 200 and 220 nm in size, respectively, were created with a 98% 99mTc radiolabeling efficiency. When injected in infected mice, betamethasone NPs presented a higher accumulation in the infected hind paw in comparison with dexamethasone NPs. Our results suggest that this nanosystem may be a valid nanoradiopharmaceutical for the detection of inflammation/infection foci in vivo.
