聚乙烯吡咯烷酮碱性水溶液中金纳米花的简易合成

以聚乙烯吡咯烷酮(PVP)兼作保护剂和还原剂在碱性水溶液中直接还原HAuCl₄制备出了60-80 nm的三维(3D)金纳米花. 产物的透射电子显微镜(TEM)和扫描电子显微镜(SEM)图像显示, 金纳米花表面布满10-15 nm左右的纳米触角, X射线衍射(XRD)表征揭示产物为金的面心立方晶体, 选区电子衍射(SAED)花样说明金纳米花为多晶结构. 金纳米花的生长经历了三个关键步骤, 即初级纳米晶聚集成多脚状纳米粒子, 随后在合适的PVP/HAuCl₄浓度比及NaOH浓度下, 多脚状纳米粒子进一步聚集形成疏松的花状粒子, 最终经过Ostwald熟化形成致密的花状产物. 一定HAuCl₄浓度下PVP/HAuCl₄浓度比和NaOH浓度对产物的形貌影响显著, 因此通过同时调控合适的PVP/HAuCl₄浓度比和NaOH浓度, 就能得到适应各种应用需求的尺度可控和纳米触角形貌可控的金纳米花.     

Hydrogen peroxide electroreduction on composite PEDOT films with included gold nanoparticles

Composite PEDOT/Au films were obtained by chemical deposition of dispersed gold nanoparticles into PEDOT (poly-3,4-ethylenedioxythiophene) conducting polymer matrix. Morphology of the obtained gold-containing films was studied by SEM and TEM methods. To study the kinetics of the hydrogen peroxide electroreduction that proceeds on glassy carbon electrodes modified with such films, we used phosphate buffer solutions containing addenda of hydrogen peroxide species. It was observed that the electroreduction process takes place on both the gold clusters?? surface and the film surface free of metal inclusions. The rate of the process is higher in the first case and rises with increasing the gold content in modifying films, but in the limit of large gold contents it is limited only by diffusion of hydrogen peroxide species in the bathing solution. A simple theory of such parallel electroreduction is proposed, which appears to allow for quantitative treatment of the obtained results.     

New approach to fabricate nanoporous gold film

A simple preparation of ultrathin nanoporous gold film was described. Copper and gold were used to fabricate Cu-Au alloy film sthrough vacuum deposition. The formation of nanoporous gold films from the alloy films involved thermal process and chemical etch by hydrochloric acid or by nitric acid. The free-standing nanoporous gold films have been analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS) and surface-enhanced Raman scattering (SERS). It was noted that the nanoporous gold film etched by hydrochloric acid is uniform with a cover of fog-like moieties.     

Fabrication of dendritic gold nanoparticles by use of an ionic polymer template

A facile method for the fabrication of dendritic gold nanoparticles (NPs) by use of an ionic polymer template has been developed. In situ generation of an imidazolium-based (cationic) polymer, poly[1-methyl-3-(4-vinylbenzyl)imidazolium], with AuCl4- counteranions is achieved by addition of HAuCl4 into a solution containing poly[1-methyl-3-(4-vinylbenzyl)imidazolium chloride]. Subsequent reduction with NaBH4 in water or in a mixture of ethanol and water affords various NPs depending on the conditions, including large dendritic gold NPs that have been analyzed by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED). The structures of the dendritic gold NPs were found to depend on the ethanol concentration. Scanning electron microscopy (SEM) images of the ionic polymer reveal that the solvent used to deposit the polymer strongly influences its structure and may be correlated to the structure of the resulting NPs.     

Human Serum Albumin Nanotubes with Esterase Activity

A nanocylindrical wall structure was obtained by layer‐by‐layer (LbL) assembly of poly‐L ‐arginine (PLA) and human serum albumin (HSA) and characterized by scanning electron microscopy (SEM), scanning force microscopy (SFM), and cryogenic transmission electron microscopy (cryo‐TEM). SEM and SFM measurements of a lyophilized powder of (PLA/HSA)₃ nanotubes yielded images of round, chimney‐like architectures with approximately 100 nm wall thickness. Cryo‐TEM images of the hydrated sample revealed that the tube walls are composed of densely packed HSA molecules. Moreover, when small‐angle X‐ray scattering was used to characterize the individual PLA and HSA components in aqueous solutions, maximum diameters of approximately 28 nm and 8 nm were obtained, respectively. These values indicate the minimum thickness of wall layers consisting of PLA and HSA. It can also be concluded from SEM as well as from cryo‐TEM images that the protein cylinders are considerably swollen in the presence of water. Furthermore, HSA retains esterase activity if assembled in nanotubes, as indicated by measurements of para‐nitrophenyl acetate hydrolysis under semi‐physiological conditions (pH 7.4, 22 °C). The enzyme activity parameters (Michaelis constant, K_m, and catalytic constant, k_cat) were comparable to those of free HSA.     

Hydrogen peroxide electroreduction on composite PEDOT films with included gold nanoparticles

Composite PEDOT/Au films were obtained by chemical deposition of dispersed gold nanoparticles into PEDOT (poly-3,4-ethylenedioxythiophene) conducting polymer matrix. Morphology of the obtained gold-containing films was studied by SEM and TEM methods. To study the kinetics of the hydrogen peroxide electroreduction that proceeds on glassy carbon electrodes modified with such films, we used phosphate buffer solutions containing addenda of hydrogen peroxide species. It was observed that the electroreduction process takes place on both the gold clusters’ surface and the film surface free of metal inclusions. The rate of the process is higher in the first case and rises with increasing the gold content in modifying films, but in the limit of large gold contents it is limited only by diffusion of hydrogen peroxide species in the bathing solution. A simple theory of such parallel electroreduction is proposed, which appears to allow for quantitative treatment of the obtained results.

     

固载型光化学传感器的形貌及结构对检测Hg2+性能的影响

采用氨丙基三乙氧基硅烷(APTES)、异氰酸酯基三乙氧基硅烷(Tri)及纳米金颗粒作为连接体,纯硅中孔分子筛HMS作为无机载体,以分子改造后的染料罗丹明B(RhB)作为有机分子,制得3种固载型光化学传感器,用于检测水中的Hg2+.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、N2物理吸附和傅里叶变换红外光谱(FTIR)对材料进行表征,并利用荧光光谱检测水溶液中的Hg2+.结果表明,3种连接体均成功地将有机分子RhB固载到HMS上,所制备的固载型光化学传感器均能够检测水溶液中的Hg2+.研究发现,固载后样品的表面形貌及孔道结构对其检测能力产生影响,具有完好表面形貌及孔道结构的样品RhB-Au-HMS对于Hg2+的检测能力最强,内部孔道坍塌的样品RhB-APTES-HMS对于Hg2+的检测能力最弱.     

Gold 3D Brush Nanoelectrode Ensembles with Enlarged Active Area for the Direct Voltammetry of Daunorubicin

3D gold brush nanoelectrode ensembles (BNEEs) consisted of gold nanowires 100 nm in diameter and 300 nm in length were fabricated by combining the technologies of template synthesis and controlled chemical etching of the membrane. The structure and morphology of the BNEEs was imaged by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The real active areas of BNEEs were found to be different when characterized by different redox species. The direct redox of daunorubicin (DNR) at the gold BNEEs exhibited absorption‐controlled characteristics and high current activity. BNEEs are reliable and effective in DNR detection.     

Synthesis of single-crystal gold nanosheets of large size in ionic liquids

Large-size single-crystal gold nanosheets have been successfully prepared by microwave heating of HAuCl(4) in ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, without any additional template agent. Transmission electron microscopy (TEM), electron diffraction (ED), scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) were used to characterize the resultant gold nanosheets. It was demonstrated that the ionic liquid could act as template agent for the formation of gold nanosheets. The present synthesis route is very simple and fast. It can be expected that the method can be extended to the fabrication of other metal nanosheets in ionic liquids.     

Synthesis and plasmonic properties of silver and gold nanoshells on polystyrene cores of different size and of gold–silver core–shell nanostructures

Simple methods of preparing silver and gold nanoshells on the surfaces of monodispersed polystyrene microspheres of different sizes as well as of silver nanoshells on free-standing gold nanoparticles are presented. The plasmon resonance absorption spectra of these materials are presented and compared to predictions of extended Mie scattering theory. Both silver and gold nanoshells were grown on polystyrene microspheres with diameters ranging from 188 to 543 nm. The commercially available, initially carboxylate-terminated polystyrene spheres were reacted with 2-aminoethanethiol hydrochloride (AET) to yield thiol-terminated microspheres to which gold nanoparticles were then attached. Reduction of silver nitrate or gold hydroxide onto these gold-decorated microspheres resulted in increasing coverage of silver or gold on the polystyrene core. The nanoshells were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and UV–vis spectroscopy. By varying the core size of the polystyrene particles and the amount of metal (silver or gold) reduced onto them, the surface plasmon resonance of the nanoshell could be tuned across the visible and the near-infrared regions of the electromagnetic spectrum. Necklace-like chain aggregate structures of gold core–silver shell nanoparticles were formed by reducing silver nitrate onto free citrate-gold nanoparticles. The plasmon resonance absorption of these nanoparticles could also be systematically tuned across the visible spectrum.     

Fabrication of hollow silica microspheres utilizing a hydrothermal approach

Hollow silica microspheres(HSMSs) have been successfully fabricated via a facile hydrothermal route using D-glucose as the sacrificial template and sodium silicate powder as the silica precursor.The resulting silica hollow particles were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),and infrared spectroscopy(IR).The surface area was determined using the BET method.SEM and TEM images exhibited micro-sized silica hollow particles with a size of ~1.5μm.     

Application of scanning electrochemical microscopy and scanning electron microscopy for the characterization of carbon-spray modified electrodes

Different gold surfaces modified by carbon-spray have been investigated by scanning electron microscopy (SEM) and scanning electrochemical microscopy (SECM). A transformation of the SECM image to a distance-location profile is proposed which assists the correlation of both images. The structures found in the transformed SECM images of carbon-spray layers on gold substrates can be explained by the topographic features visible in the SEM pictures. Tempering the carbon spray results in an increased density of electrochemically reactive carbon particles which could be confirmed by cyclic voltammetric investigations. Gold minigrids modified with carbon spray expose some areas of especially large currents which could not be predicted from their SEM images. This effect may result from particles located at the edge of a wire intersection having relatively large active surfaces per particle. They contribute significantly to the total current of the minigrid.     

A new preparation method of gold nanoparticles by intra-reduction of sodium gold（I） sulfite

In this study, well-dispersed gold nanoparticles were prepared by using intra-molecular reduction of sodium gold sulfite, without using additional reductants and chloride free. The technical parameters including transformation temperature, pH, and concentration were optimized by the single-factor method as 90 C, pH 1, and 0.01 mmol/L [Na3Au（SO3）2], respectively. The resultant colloidal transmission electron microscopy images （TEM） and UV-vis absorption spectrophotometer spectra were acquired to check their properties, and the results show this kind of colloidal gold is controlled to 6 nm in sizes and has good stability in solution.     

Y_2O_2S:Eu~(3+)空心微球的制备与性能

以单分散的碳球为硬模板,采用均匀共沉淀法合成了Y_2O_2S:Eu~(3+)心微球.通过XRD、SEM、TEM、荧光光谱对其进行表征.X射线衍射测试表明所制备的Y_2O_2S:Eu~(3+)空心微球为单相,六方晶.扫描电子显微镜(SEM)和透射电子显微镜(TEM)测试表明所制备的Y_2O_2S:Eu~(3+)空心微球粒径小,分布均匀.激发和发射光谱测试表明Eu~(3+)离子能有效地掺入硫氧化钇基质中,并具有良好的发光性能.     

Selective-precursor reducing route to cobalt nanocrystals and ferromagnetic property

Cobalt nanocrystals were prepared by controlled chemical route at mild condition through selective-precursor reducing synthesis. Nanorod bundles and three-dimensional (3D) dendritic nanocrystal networks of Co were prepared by selecting different precursors. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) technologies. Field-emission scanning electron microscopy (FE-SEM), SEM, and TEM images indicate the nanorod bundles mainly consist of nanorods with the diameter of 70 nm. In 3D dendritic nanocrystal networks there are numerous secondary and sub-secondary branches were grown at right angles on each main stem. Room temperature magnetic measure of the Co samples demonstrates much enhanced ferromagnetic property, which might be attributed to their organization of specific shape. The possible formation mechanism of the cobalt nanocrystals with different morphologies was also discussed.     

Synthesis and characterization of positively charged,alumina‐coated silica/polystyrene hybrid nanoparticles via pickering miniemulsion polymerization

Positively charged, raspberry‐like hybrid nanoparticles, consisting of a polystyrene core and an alumina‐coated silica shell were successfully prepared in a surfactant free system via the radical copolymerization of styrene (St) and different comonomers (acrylic acid, methacrylic acid, and acrylamide) by using a cationic silica sol as the sole emulsifier in Pickering miniemulsion polymerization. The influence of different parameters like pH of the dispersion, comonomer content, and the amount and size of silica nanoparticles on the colloidal stability of the systems, prepared with different comonomers, was examined. The particles' morphology was observed via high‐resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The removal of free silica particles via centrifugation was proved by TEM and SEM, and the content of free and adsorbed silica was quantified via thermogravimetric analysis (TGA). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Lamellar metal-organic complex and its rod-like nanoparticles prepared with ultrasonic technique

Metal-organic complex (H3NCH2CH2NH2)3[MoO2(OC6H4O)2] with a lamellar morphology has been syn- thesized. Its crystal structure was confirmed by single-crystal X-ray diffraction. The morphology of the crystal was observed by scanning electron microscopy (SEM). The metal-organic nanoparticles have been prepared by using an ultrasonic method. The morphology of the as-prepared nanoparticles was observed by transmission electron microscopy (TEM). The possible formation mechanism has also been proposed.     

Preparation and Characterization of NiO Nanoparticles Via Solid-State Thermal Decomposition of Nickel(II) Schiff Base Complexes [Ni(salophen)] and [Ni(Me-salophen)]

This study focuses on the preparation and characterization of nickel oxide nanoparticles from nickel(II) Schiff base complexes as new precursors. At first nickel(II) complexes [Ni(salophen)] and [Ni(Me-salophen)] were synthesized and characterized by elemental analyses and FT-IR spectroscopy. Then NiO nanoparticles were prepared by solid-state thermal decomposition at 550 ºC for 3.5 h. The FT-IR spectrum confirmed the composition of products. The crystalline structures and morphology of products were studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD results revealed that the obtained products were nickel oxide. SEM and TEM images demonstrated that the NiO nanoparticles have uniform shape with size between 35 and 70 nm.     

Influence of different substrates on ZnO nanorod arrays properties

Zinc Oxide (ZnO) nanorod arrays were grown on different substrates by hydrothermal method. The crystallinity of ZnO nanorod was regularly investigated by X-ray diffraction (XRD). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine morphology of the ZnO nanorods. The results indicate that the nanorods grow along [002] orientation. SEM and TEM images and XRD patterns show that the growth of ZnO nanorods on graphene/Quartz substrate is better than the other substrates due to the number and size of the nanorods which are highly affected through the properties of ZnO seed layers and it has lower defects than the other substrates. PL spectra ZnO would have a higher concentration of oxygen vacancy.     

Detection of protein coatings on nanoparticles surfaces by ToF‐SIMS and advanced electron microscopy

In this study, time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and advanced electron microscopy (scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and transmission electron microscopy (TEM)) were applied to detect and analyse different nano‐scaled protein coatings on gold nanoparticles (NP). The NP were coated with collagen type I and fibronectin as well as different combinations of these proteins. These two main proteins in human cell organization and tissue formation were identified with the aid of ToF‐SIMS by typical amino acid mass peak detection. In addition, the protein‐coated particles were investigated by TEM and SEM to get information about the protein structure, the protein layer thickness on the particle surfaces and the reaction of NP in different protein solutions. In this study, a differentiation of diverse protein induced particle agglomeration was proven. The investigations of this study were part of the Specific Targeted Research Project CellNanoTox (project no. NMP4‐CT‐2006‐032731) funded by the European Commission under the 6th EU Framework Programme for Research and Technological Development. Copyright © 2013 John Wiley & Sons, Ltd.