Parallel patterning of nanoparticles via electrodynamic focusing of charged aerosols

The development of nanodevices that exploit the unique properties of nanoparticles will require high-speed methods for patterning surfaces with nanoparticles over large areas and with high resolution. Moreover, the technique will need to work with both conducting and non-conducting surfaces. Here we report an ion-induced parallel-focusing approach that satisfies all requirements. Charged monodisperse aerosol nanoparticles are deposited onto a surface patterned with a photoresist while ions of the same polarity are introduced into the deposition chamber in the presence of an applied electric field. The ions accumulate on the photoresist, modifying the applied field to produce nanoscopic electrostatic lenses that focus the nanoparticles onto the exposed parts of the surface. We have demonstrated that the technique could produce high-resolution patterns at high speed on both conducting (p-type silicon) and non-conducting (silica) surfaces. Moreover, the feature sizes in the nanoparticle patterns were significantly smaller than those in the original photoresist pattern.     

Grafting of polymers from clay nanoparticles via high-dose gamma-ray irradiation

In this work, the prepared mixture of low concentration of ethyl acrylate (EA) monomers and organophilic montmorillonite (OMMT) particles in methanol solution was exposed to gamma-ray (γ-ray) irradiation. It was found that EA monomers first polymerized at relatively low radiation dose (< 10 kGy), then the polymerized PEA chains can graft onto the OMMT particles when the radiation dose increases above 185 kGy. Electron spin resonance (ESR) tests verified that a large amount of radicals could be created on PEA chains and the OMMT particles at high radiation dose. When the radicals on the PEA chains combined with the radicals on the surface of silicate layers of OMMT particles, the grafting reaction took place. Furthermore, Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD) results all confirmed the presence of PEA grafting on the surface of the stacking silicate layers of OMMT particles.     

直流电弧放电法合成In2O3纳米粒子

电弧放电法因能在瞬间产生高温使原料气化而成为一种高效的纳米材料制备方法。以金属In为原料,在无催化剂的条件下,采用直流电弧放电法直接合成了In2O3纳米粒子。XRD、SEM和TEM结果表明所制备的In2O3纳米粒子为立方结构,形貌为结晶良好的八面体,平均粒径为60～120nm。纳米粒子之间以点接触和面接触相连。     

Preparation of size-controlled tungsten oxide nanoparticles and evaluation of their adsorption performance

The present study investigated the effects of particle size on the adsorption performance of tungsten oxide nanoparticles. Nanoparticles 18-73 nm in diameter were prepared by evaporation of bulk tungsten oxide particles using a flame spray process. Annealing plasma-made tungsten oxide nanoparticles produced particles with diameters of 7-19 nm. The mechanism of nanoparticle formation for each synthetic route was examined. The low-cost, solid-fed flame process readily produced highly crystalline tungsten oxide nanoparticles with controllable size and a remarkably high adsorption capability. These nanoparticles are comparable to those prepared using the more expensive plasma process.     

Improvement of medical applicability of hydroxyapatite/graphene oxide nanocomposites via additional yttrium oxide nanoparticles

Hydroxyapatite is one of the most studied bioactive materials in the biomedical field. However, Hydroxyapatite’s low mechanical strength and low fracture toughness represent a limitation in its applications as a load-bearing biomaterial. Yttrium oxide and graphene oxide (GO) have previously been shown to enhance these mechanical characterization of hydroxyapatite (HAP) when combined in binary nanocomposites. In this study, a novel ternary nanocomposite hydroxyapatite/yttrium oxide/graphene oxide has been developed and its characteristics have been compared to the nanoparticles and binary nanocomposites of its components. The compositions of the prepared materials have been confirmed. The typical morphologies of the three components of the nanocomposites have been shown by scanning and transmission electron microscopes with HAP nanoparticles. The average roughness has decreased from 11.4 nm in the nanoparticles of the pure HAP to 7.9 nm in the ternary nanocomposite. All prepared nanocomposites have shown an acceptable slight decrease in cell viability with 96.9 ± 3.5% cell viability in the composite. The ternary nanocomposite has also shown a higher antibacterial activity compared to its individual constituents, with a zone of inhibition of 12.9 ± 1.1 mm and 12.5 ± 0.9 mm against E. coli and S. aureus, respectively, compared to no inhibition in the case of pure Hydroxyapatite.     

Synthesis and characterization of tin oxide nanoparticles via the Co-precipitation method

The present study illustrates the characteristics and co-precipitation method for synthesis of tin oxide nanoparticles. The tin oxide nanoparticles were produced using tin chloride, Triton X-100 and ammonia precipitators. Structure, size and surface morphology of the tin oxide was studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results show sphere shaped tin oxide nanoparticles without chlorine contamination. The crystallite size determined by the Scherrer formula is about 23 nm. Lattice parameters calculated by Nelson-Riley equation show high quality of crystallization.     

Formation of silver nanoparticles in low-alkali borosilicate glass via silver oxide intermediates

A successful procedure has been worked out for the subsequent colouration of low-alkali borosilicate glass that comprises silver doping by silver/sodium ion exchange below the glass transformation temperature followed by thermal processing well above, at 750 °C. The particle formation process as studied by electron microscopy and optical spectroscopy revealed the formation of silver nanoparticles proceeding via silver oxide intermediates. The intermediate nanoparticles are supposed to result from a phase separation within the silver ion-doped glass. Their formation and succeeding transformation to silver nanoparticles upon thermal processing is accompanied by characteristic absorption peaks in the visible range which gradually convert to the surface plasmon resonance of spherical silver nanoparticles. The optical density of the silver-based colouration achieved this way assumes values comparable to those usually obtained with soda lime silicate glass.     

Three-dimensional assembly of nanoparticles from charged aerosols

The capability of assembling nanoparticles into a desired ordered pattern is a key to realize novel devices which are based not only on the unique properties of nanoparticles but also on the arrangements of nanoparticles. While two-dimensional arrays of nanoparticles have been successfully demonstrated by various techniques, a controlled way of building ordered arrays of three-dimensional (3D) nanoparticle structures remains challenging. We report that a variety of 3D nanoparticle structures can be formed in a controlled way based on the ion-induced focusing, electrical scaffold, and antenna effects from charged aerosols. Particle trajectory calculations successfully predict the whole process of 3D assembly. New surface enhanced Raman scattering substrates based on our 3D assembly were constructed as an example showing the viability of the present approach. This report extends the current capability of positioning nanoparticles on surface to another spatial dimension, which can serve as the foundation of future optical, magnetic, and electronic devices taking the advantage of multidimensions.     

Synthesis of monodisperse iron oxide and iron/iron oxide core/shell nanoparticles via iron-oleylamine complex

Monodisperse magnetic nanoparticles are of great scientific and technical interests. This paper reports a single-step synthesis of monodisperse magnetite nanoparticles with particle size of 8 nm. Iron/maghaemite core/shell nanoparticles with particle size of 11 nm were obtained by reducing the concentration of oleylamine. TEM and in-situ FTIR results suggested that iron-oleylamine intermediate was generated in-situ and decomposed at higher temperature. Oleylamine was also found on the surface of nanoparticles, indicating its role as capping agent which provided steric protection of as-synthesized nanoparticles from agglomeration. Both magnetite and iron/maghaemite core/shell nanoparticles were superparamagnetic at room temperature with a blocking temperature at 80 K and 67 K, respectively.     

烷基铵在低层电荷蒙脱石上的等温吸附

蒙脱石/烷基铵复合物是一种高附加值的矿物复合材料,复合物中烷基铵的吸附量与其凝胶性能密切相关。以山东某低层电荷的膨润土为原料,在提纯、钠化的基础上,系统研究了80℃恒温条件下十八烷基三甲基铵(OTC)、十六烷基三甲基铵(CTAC)及十四烷基三甲基铵(TTAC)在蒙脱石上的等温吸附特性。研究结果表明,在80℃恒温交换体系中,当烷基铵的用量较高时,3种烷基铵在蒙脱石上均呈现超量吸附,且饱和吸附量都随着碳链长度的增加而增加。3种烷基铵在蒙脱石上的等温吸附特性均与Modified Lang-muir模型拟合较好,吸附数据曲线与Modified Lang-muir模型拟合度分别为0.992、0.986和0.979,相应的蒙脱石对烷基铵饱和吸附量分别是2.101、2.042和1.760mmol/g,与实验数据吻合较好。     

Integration of zinc oxide nanoparticles into transparent poly(butanediolmonoacrylate) via photopolymerisation

A new method for the preparation of transparent ZnO/PBDMA nanocomposites (PBDMA = poly(butanediolmonoacrylate)) is reported. Zinc oxide nanocrystals (4-10 nm) were synthesized in ethanol and then transferred into butanediolmonoacrylate (BDMA) to obtain a transparent and stable colloidal suspension. No further growth or aggregation of the particles could be observed, after dispersing the particles in the monomer. Effective size control in the range of 6-10 nm and concentrations up to 10 wt% zinc oxide were demonstrated for these systems. The particles and suspensions were characterized by transmission electron microscopy, X-ray diffraction, UV-VIS spectroscopy and dynamic light scattering. The addition of trimethylolpropane triacrylate (TMPTA) and a photoinitiator to the ZnO/BDMA suspension lead to a UV-curable liquid. Photoinduced polymerization was used to produce transparent nanocomposites containing the nanoparticles. The material exhibits a strong UV absorption below 360 nm, a high transmission (90%) in the visible spectral range and a green photoluminescence.     

Immobilization of functional oxide nanoparticles on silicon surfaces via Si-C bonded polymer brushes

A method for immobilizing and mediating the spatial distribution of functional oxide (such as SiO2 and Fe3O4) nanoparticles (NPs) on (100)-oriented single crystal silicon surface, via Si-C bonded poly(3-(trimethoxysilyl)propyl methacrylate) (P(TMSPM)) brushes from surface-initiated atom transfer radical polymerization (ATRP) of (3-(trimethoxysilyl)propyl methacrylate) (TMSPM), was described. The ATRP initiator was covalently immobilized via UV-induced hydrosilylation of 4-vinylbenzyl chloride (VBC) with the hydrogen-terminated Si(100) surface (Si-H surface). The surface-immobilized Fe3O4 NPs retained their superparamagnetic characteristics and their magnetization intensity could be mediated by adjusting the thickness of the P(TMSPM) brushes.     

Synthesis of neodymium hydroxide nanotubes and nanorods by soft chemical process

A facile soft chemical approach using cetyltrimethylammonium bromide (CTAB) as template is successfully designed for synthesis of neodymium hydroxide nanotubes. These nanotubes have an average outer diameter around 20 nm, inner diameter around 2 nm, and length ranging from 100 to 120 nm, high BET surface area of 495.71 m(2) g(-1). We also find that neodymium hydroxide nanorods would be obtained when CTAB absented in reaction system. The Nd(OH)3 nanorods might act as precursors that are converted into Nd2O3 nanorods through dehydration at 550 degrees C. The nanorods could exhibit upconversion emission characteristic under excitation of 591 nm at room temperature.     

Microstructure and hemocompatibility of neodymium doped zinc oxide thin films

By the radio frequency magnetron sputtering, both un-doped and neodymium (Nd) doped ZnO thin films were grown on Si (100) substrates. The microstructure of the films has preferred c-axis growth orientation confirmed by the X-ray diffraction spectra. The crystallite size of ZnO crystallite decreases with the increasing of Nd concentration. We show that the hemocompatibility can be improved by a suitable Nd doping in the ZnO thin films. It is verified by both calculations on surface energy and interfacial tension of the sample, and experiments on the wettability, the proteins adsorption, and the platelets adhesion.     

Generation of charged nanoparticles in point ion sources

The conditions of formation of a dispersed phase in a point source of indium and tin ions have been studied. Charged droplets are generated in a threshold manner at a certain value of the ion beam current. This is accompanied by the excitation of ion current oscillations at a frequency of 15–20 MHz as a result of the capillary instability of the conducting liquid surface in a strong electric field. The dimensions of emitted nanoparticles determined using an electron microscope are continuously distributed in a range of 2–20 nm, and their average specific charge amounts to 5 × 10⁴ C/kg. Such charged nanodroplets can be used to create various surface quantum structures. The possibility of obtaining nanoparticles of semiconductor materials using a modified source with a porous electrode is discussed.     

Preparation and magnetic properties of fibrous gamma iron oxide nanoparticles via a nonaqueous medium

Fibrous shape γ-Fe₂O₃ nanoparticles (the length of ∼850 nm; the width of ∼5 nm) have been prepared using lauryl alcohol as a nonaqueous medium. The resultant products were investigated by IR, TG–DTA, XRD, TEM and magnetization measurements. For the preparation of pure γ-Fe₂O₃ nanoparticles, the suitable condition of the molar ratio of lauryl alcohol to iron nitrate is determined to be 1 : 2 and the appropriate temperature is in the range of 300–400 °C. The magnetization measurements reveal that the obtained γ-Fe₂O₃ particles possess better magnetic properties for application in magnetic recording. It can be concluded that lauryl alcohol plays an important role not only in controlling the dimension, shape of the products, but also in helping the increase of magnetic properties.     

Regio-specific adsorption of cytochrome c on negatively charged surfaces

Studies are reported on the identification of the chromatographic contact domain of equine cytochrome c during its interaction with negatively charged sorbents. A negatively charged resin was designed that would simultaneously adsorb the protein electrostatically and covalently bind it through amide bond formation to succinate groups coupled to the support in an ester linkage. Protein immobilization occurred through lysine residues participating in electrostatic adsorbed cytochrome c to the resin surface. After covalent bond formation in the interface between the protein and the sorbent, ester linkages coupling succinate groups to the support were hydrolyzed, and the protein was released. Lysine residues on the protein that had participated in covalent capture were labeled with succinate residues. The tagged protein was then tryptic-mapped and the peptides were examined by matrix-assisted laser desorption ionization mass spectrometry to determine the position of the amino acids that had been tagged. Comparing the tagged sites with the X-ray crystallographic structure of cytochrome c, it was concluded that a single face of the protein dominated the adsorption process and the 3-D structure of the protein remained largely undisturbed during adsorption.     

Cerium oxide nanoparticles via gel-combustion for electrochemical investigation of pantoprazole in the presence of epinephrine

Journal of Materials Science: Materials in Electronics - In this work, cerium oxide nanoparticles (CeO2NPs) were prepared by naturally available Aloe-Vera (AV) gel as fuel via gel-combustion...     

Strong adsorption of chlorotetracycline on magnetite nanoparticles

In this work, environmentally friendly magnetite nanoparticles (Fe₃O₄ MNPs) were used to adsorb chlorotetracycline (CTC) from aqueous media. Fe₃O₄ MNPs exhibit ultrahigh adsorption ability to this widely used antibiotic. The adsorption behavior of CTC on Fe₃O₄ MNPs fitted the pseudo-second-order kinetics model, and the adsorption equilibrium was achieved within 10 h. The maximum Langmuir adsorption capacity of CTC on Fe₃O₄ (476 mg g⁻¹) was obtained at pH 6.5. Thermodynamic parameters calculated from the adsorption data at different temperature showed that the adsorption reaction was endothermic and spontaneous. Low concentration of NaCl and foreign divalent cations hardly affected the adsorption. Negative effect of coexisting humic acid (HA) on CTC adsorption was also observed when the concentration of HA was lower than 20 mg L⁻¹. But high concentration of HA (>20 mg L⁻¹) increased the CTC adsorption on Fe₃O₄ MNPs. The matrix effect of several environmental water samples on CTC adsorption was not evident. Fe₃O₄ MNPs were regenerated by treatment with H₂O₂ or calcination at 400 °C in N₂ atmosphere after separation from water solution by an external magnet. This research provided a high efficient and reusable adsorbent to remove CTC selectively from aqueous media.