Enhancement of Raman Scattering of 1,4-Benzenedithiol by CdS Nanoparticles Assembled on a Silver Surface

CAS nanoparticles were assembled on the smooth surface of a piece of silver by using 1,4-benzenedithiol as coupling molecules. The SEM and resonance Raman spectroscopic characterizations demonstrate that the nanosized structure of CdS was still preserved upon assembly, and a two-dimensional structure of CdS nanoparticles was formed on the substrate surface. The FT-Raman spectra indicate that 1,4-benzenedithiol was coupled between CAS nanoparticles and the silver surface with a tilted orientation. The Raman scattering of 1,4-benzenedithiol was substantially enhanced by the assembled CdS nanoparticles, probably due to the alteration of the polarizability of 1,4-benzenedithiol and the electromagnetic interaction between the dipoles of the CdS particle with its image in the metal substrate.     

Synthesis of GoldMag particles with assembled structure and their applications in immunoassay

Micrometer-sized Fe3O4 particles and nano-sized gold particles were first synthesized by methods of self-aggregation of surface-chemically modified Fe3O4 nanoparticles and citrate reduction of the Au3 to Au0, respectively. Interaction between these two types of particles resulted in the assembly of nano-sized gold particles on the surface of the micrometer-sized Fe3O4 particles, forming an assembled structure with the Fe3O4 core particles around which are attached nano-sized gold parti- cles. The Fe3O4/Au structure is named GoldMag particles with assembled structure. The synthetic process, structure, and magnetic property of the GoldMag particles were analyzed. GoldMag particles with assembled structure have an irregular shape, rough surface with a diameter of 2―3 μm. These particles exhibit the superparamagnetic property with saturated magnetization of 41 A·m2/kg. In a single step, antibodies could be readily immobilized onto the surface of the particles with a high binding capacity. The GoldMag particles can be used as a novel carrier in immunoassays. The maximum quantity of human IgG immobilized onto GoldMag particles was 330 μg/mg. In order to validate the quality of the GoldMag particles as immunoassay carriers, an immunoassay system was used. The relative amount of immobilized human IgG was measured by HRP-labeled anti human IgG. The coefficient of variation within parallel samples of each group was below 6% and the coefficient of variation of means between five groups carried out separately was below 7%. Based on the sandwich method, the Hepatitis B surface antigen (HBsAg) and interleukin-8 (IL-8) were also analyzed by qualitative and quantitative detection, respectively. The result indicated that the GoldMag particles with assembled structure were an ideal carrier in immunoassay.     

功能化荧光素掺杂二氧化硅纳米粒子用于免疫层析试验

A simple but effective approach was developed to synthesize amino functionalized fluorescein isothiocyanate-doped silica nanoparticles based upon polycondensation of tetraethoxysilane. Organic dye molecule (fluorescein isothiocyanate) coupled with a silane coupling agent, 3-aminopropyltriethoxysilane, was incorporated into silica sphere through controlled hydrolysis and polymerization of tetraethoxysilane. The dye was connected with silica sphere through 3-aminopropyltriethoxysilane, which avoided the leakage of the dye. The cohydrolysis and polymerization of tetraethoxysilane and 3-aminopropyltriethoxysilane outside the surface of the silica sphere formed another thin silica shell with the functionalized amino groups on the surface. With amino groups on the surface, the nanoparticle surface was affluent in positive charges. The amino-functionalized nanoparticles were linked with mouse monoclonal antibody against hepatitis B virus surface antigen through electrostatic interaction to form fluorescence probes, which were tested by immunochromatographic assay using immunochromatography test strip. It was indicated that the fluorescence probe was suitable for immunoassay.     

Chemical interactions between silver nanoparticles and thiols: a comparison of mercaptohexanol against cysteine

The interaction between citrate capped silver nanoparticles and two different thiols, mercaptohexanol(MH) and cysteine, was investigated. The thiols interacted with silver nanoparticles in a significantly contrasting manner. With MH, a sparingly soluble silver(I) thiolate complex AgSRm(Rm = –(CH2)6OH) was formed on the silver nanoparticle surface. Cyclic voltammograms and UV-vis spectra were used to infer that the AgSRm complex on the nanoparticle surface undergoes a phase transition to give a mixture of AgSRm and Ag2S-like complexes. In contrast, when silver nanoparticles were exposed to cysteine, the citrate capping agent on the silver nanoparticles was replaced by cysteine to give cysteine capped nanoparticles. As cysteine capped nanoparticles form, the electrochemical data displayed a decrease in oxidative peak charge but the UV-vis spectra showed a constant signal. Therefore, cysteine capped nanoparticles were suggested to have either inactivated the silver surface or else promoted detachment from the electrode surface.     

Effect of catalyst confinement and pore size on Fischer-Tropsch synthesis over cobalt supported on carbon nanotubes

This paper studies the impact of structure of cobalt catalysts supported on carbon nanotubes(CNT) on the activity and product selectivity of Fischer-Tropsch synthesis(FTS) reaction.Three types of CNT with average pore sizes of 5,11,and 17 nm were used as the supports.The catalysts were prepared by selectively impregnating cobalt nanoparticles either inside or outside CNT.The TPR results indicated that the catalyst with Co particles inside CNT was easier to be reduced than those outside CNT,and the reducibility of cobalt oxide particles inside the CNT decreased with the cobalt oxide particle size increasing.The activity of the catalyst with Co inside CNT was higher than that of catalysts with Co particles outside CNT.Smaller CNT pore size also appears to enhance the catalyst reduction and FTS activity due to the little interaction between cobalt oxide with carbon and the enhanced electron shift on the non-planar carbon tube surface.     

Synthesis and Characterization of CdSe Nanocrystals Capped by CdS

CdSe semiconductor nanocrystals capped by CdS were synthesized in the aqueous solution with 2-mercaptoethanol as the stabilizer. The CdS capping with a higher band-gap than that of the core crystallite has successfully eliminated the surface traps. Optical absorption and fluorescence emission spectra were used to probe the effect of CdS passivation on the electronic structure of the nanocrystals. The composite CdSe/CdS nanocrystals exhibit strong, narrow(FWHM≤40 nm) and stable band-edge photoluminescence. X-ray powder diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy were used to analyze the composite nanocrystals and determine their average size, size distribution, shape, internal structure and elemental composition.     

High immobilization of antibacterial moieties onto monodisperse microspheres by dispersion polymerization using bicationic viologen surfmer

In order to achieve monodisperse particles with high content of antibacterial groups covalently bonded on surface, a bicationic viologen,N-hexyl-N’-(4-vinylbenzyl)-4,4’-bipyridinium bromide chloride(HW) was devised as a surfmer in dispersion polymerization of styrene(St) using a mixture of methanol(or ethylene glycol) and water as media.Effects of content of HW,its addition profile and composition of reaction media on particles size and incorporation of HW moieties were mainly investigated.The attachment of silver and gold nanoparticles on particle surface under UV irradiation ascertained the surface-bonded HW segments.SEM,TEM observations and XPS,zata potential measurements indicated that increase of initial HW contents and addition of HW(when polymerization had been performed for 3 h) led to grown particles and enhanced immobilization of HW moieties.Using a mixture of ethylene glycol and water as reaction media, small particles(520-142 nm) with highly attached HW moieties were prepared.Furthermore,antibacterial efficacy of the resultant particles against S.aureus was assayed,and particles with more HW moieties anchored on surface demonstrated greater efficiency of antibacterial activity.     

Effect of Preparation Methods of Bi2O3 Nanoparticles on their Photocatalytic Activity

Bi2O3 nanoparticles were prepared by means of ammonia precipitation, polyol mediated methods and microemulsion chemical method. The structure and properties of the as-prepared nanoparticles, having been submitted to a heat-treatment test at 750℃, were characterized by means of XRD. BET, XPS and UV-Vis absorption techniques. The photocatalytic oxidation reactions of benzene, toluene and xylene were used as the model reaction to measure the photocatalytic activity of Bi2O3 nanoparticles, respectively. The results show that the crystallite size of Bi2O3 prepared with different methods and calcined at 750℃ were 50. 6, 38.5 and 31.5 nm, respectively. The photocatalytic activity of Bi2O3 nanoparticles prepared with the microemulsion chemical method was higher than that of the particles prepared with the polyol mediated method; and that of the particles prepared with the micromulsion chemical method was the highest among the three. The degradation rates of the three pollutants xylene, toluene and benzene decreased in sequence.     

磷化镓纳米粒子的固氮

Under mild ambient conditions gallium phosphide （GAP） nanoparticles were employed to carry out the reduction of nitrogen. By using Nessler＇s reagent ammonia was detected in the slurry where the aggregated GAP particles were suspended in water and bubbled by pure nitrogen. Dependence of the concentration of ammonia upon bubbring time, velocity of the flow of nitrogen, and dosage of GAP particles was investigated. In comparison with the original GAP nanoparticles, the Raman scattering of the GAP particles undergoing the process of nitrogen fixation reveals that two sharp lines at 138 and 182 cm^-1, respectively, emerged from the broad continuum around 100-200 cm^-1. These two lines might be assigned to the translational motions of ammonia adsorbed on the surface of the GAP particles. An assessment of the infrared spectra of the two GAP particles led to the conclusion that the environment of the two H2O molecules was not identical. Analysis of the electron spin resonance results showed that the structure defect, gallium self-interstitial, was not involved in the nitrogen fixation of the GAP nanoparticles.     

Preparation and evaluation of Fe3O4-core@Ag-shell nanoeggs for the development of fingerprints

The surface of individual, relatively dispersed Fe3O4 nanospheres is coated with a thiol-terminated silane, then the thiol on the Fe3O4 particles’ surfaces treats with nano-Ag colloidal solution to form Ag-modified Fe3O4 nanoparticles. Eventually, a solid shell of Ag is capped onto the Ag-modified Fe3O4 nanoparticles by reducing aliquots of AgNO3 solution using NaBH4 as a reducing agent. The as-prepared Fe3O4 -core@Ag-shell nanoeggs, which are uniform in size, highly monodisperse, stable against aggregation and have high magnetization, were depended on thin shell of the attached nano-Ag, the size of Fe3O4 nanoparticles, the volume of thiol-terminated silane as well as the ultrasonication. The Fe3O4 -core@Ag-shell nanoeggs are proposed to detect fingermarks on different surface, with which the fingermarks can be viewed directly, due to the clear ridge detail.     

Semiconductor nanoparticle/polystyrene latex composite materials

Cadmium sulfide and cadmium selenide/cadmium sulfide core/shell nanoparticles stabilized with poly(cysteine acrylamide) have been bound to polystyrene (PS) latexes by three methods. First, anionic 5 nm diameter CdS particles were electrostatically attached to 130 nm surfactant-free cationic PS latexes to form stable dispersions when the amount of CdS particles was less than 10% of the amount required to form a monolayer on the surface of the PS particles or when the amount of CdS particles exceeded the amount required to form a monolayer on the PS particles. Transmission electron microscopy (TEM) showed nanoparticles on the surface of the latex particles. Fluorescence spectra showed unchanged emission from the nanoparticles. Second, anionic, surfactant-free PS latexes were synthesized in the presence of CdS and CdSe/CdS nanoparticles. TEM showed monodisperse latex particles with trapped nanoparticles. Third, surfactant-stabilized latexes were synthesized by copolymerization of styrene with vinylbenzyl(trimethyl)ammonium chloride electrostatically bound to the CdSe/CdS nanoparticle surface. Brownian motion of the submicroscopic composite particles in water was detected by fluorescence microscopy.     

CdS/TiO2复合纳米微粒的原位合成及性质研究

采用一种新方法,在TiO₂表面原位合成CdS纳米微粒,并用红外光谱跟踪了CdS/TiO₂复合纳米微粒的形成过程.紫外吸收光谱研究表明TiO₂对CdS纳米微粒的形成有很好的稳定作用,荧光光谱研究结果表明,这种纳米异质结构有着良好的电荷分离.     

水溶性CdSe/CdS量子点的合成及其与牛血清蛋白的共轭作用

用巯基乙酸(TGA)作为稳定剂，合成了水溶性的CdSe和核壳结构的CdSe/CdS半导体量子点。吸收光谱和荧光光谱研究表明，核壳结构的CdSe/CdS半导体量子点比单一的CdSe量子点具有更优异的发光特性。用TEM、电子衍射(ED)和XPS分别表征了CdSe和CdSe/CdS纳米微粒的结构、形貌及分散性。红外光谱和核磁共振谱证实了巯基乙酸分子中的硫原子和氧原子与纳米微粒表面的金属离子发生了配位作用。在pH值为7.4的条件下，将合成的CdSe和CdSe/CdS量子点直接与牛血清白蛋白(BSA)相互作用。实验发现，两种量子点均对BSA的荧光产生较强的静态猝灭作用；而BSA对两种量子点的荧光则具有显著的荧光增敏作用，存在BSA时CdSe/CdS量子点的荧光增强是不存在BSA时体系荧光强度的3倍。     

Synthesis of CdS nanoparticles in colloidal state and its possible interaction with tyrosine

The basic objective is to develop a simpler method of preparation of the colloidal CdS nanoparticles with greater stability and to study interaction with tyrosine molecules. Average size of the particles in the colloid is found to be about 3 nm as probed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. Effect of both sulfide enriched CdS as well as Cd(2+) enriched CdS on tyrosine is investigated both through absorbance and emission spectroscopy. Quenching of tyrosine emission followed Stern-Volmer relation and was found to be independent of temperature, indicating possible static quenching. However, Forster transfer between tyrosine and CdS can be suspected to mimic static quenching in addition to the charge transfer complexes. In the presence of Cd(2+) enriched CdS nanoparticles, the emission of tyrosine in phosphate buffer shows typical spectral broadening and a long wavelength increase in fluorescence emission. This may be attributed to the sensitized emission of CdS itself.     

A Simple Approach to Fabricate CdS-SiO2 Hybrid Microspheres by Producing CdS Nanoparticles on the Surface of Thiolated SiO2 Microspheres

IntroductionSemiconductor nanoparticles show a quantum sizeeffect and have attracted much attention because oftheir unique photochemical and photophysical proper-ties[1—4].In recent years,quantumdots of CdS and in-organic nanoparticles hybrid composites …     

Cds纳米微粒的聚四氟乙烯多孔膜法制备及其表面修饰

硫化镉;Cds纳米微粒的聚四氟乙烯多孔膜法制备及其表面修饰;纳米粒;多孔膜;表面修饰;聚四氟乙烯     

水热法合成CdS/ZnO核壳结构纳米微粒

以半胱氨酸镉配合物为前驱体,采用水热法合成CdS纳米微粒,并以ZnO对其进行表面修饰,形成具有核／壳结构的CdS／ZnO半导体纳米微粒,CdS纳米微粒表面经ZnO修饰后,其带边发射大大增强,透射电镜显示,110℃下反应4h所得的CdS／ZnO颗粒尺寸约为20nm,电子衍射表明其结构为六方相。     

Preparation and electrorheological characteristic of CdS/Polystyrene composite particles

Cadmium sulfide/polystyrene (CdS/PS) hybrid particles were synthesized and their physical characteristics including electrorheology were examined. Monodisperse CdS/PS nanocomposite particles with diameters of 2 μm were obtained via dispersion polymerization. To form cadmium sulfide nanoparticles onto the PS surface, 2-(dimethylamino)ethyl methacrylate was used as a functional monomer for coordinating with Cd²⁺ ions. Finally, cadmium sulfide nanoparticles with size < 10 nm were formed with the release of S²⁻ ions from thioacetamide. The morphology of the as-prepared CdS/PS nanocomposite particles clearly showed that the CdS particles are present on the surface of the PS. The optical properties were also studied. In addition, their electrorheological characteristics were confirmed by using optical microscopy with applied electrical field. Recently, dielectric properties of CdS nanoparticles were already reported; however, electrorheological characteristics of CdS/PS nanocomposite particles were investigated for the first time.     

Synthesis of a hybrid material from CdS nanoparticles and carbon nanotubes

A method for synthesis of a hybrid material from CdS nanoparticles and carbon nanotubes (CNT) by the precipitation of CdS nanoparticles on the CNT surface from an aqueous solution containing the Cd^II salt, thiourea, and ammonia was developed. The dependences of the size of particles formed on the CNT on the temperature of the solution and the duration of precipitation were observed. The degree of imperfection of the CNT surface exerts a substantial effect on the density of the precipitated CdS particles.     

Effect of the Spherical Silica Surface on the Photoluminescence of the Loaded CdS Nanoparticles

CdS nanoparticles were formed on the surface of silica microspheres by the improved layer‐by‐layer self‐assembled technique. High‐resolution electron microscope (HRTEM) image and energy dispersive x‐ray analysis (EDX) confirmed formation of a quasi‐continuous CdS nanoparticles film on the silica microspheres. The results of UV‐vis and fluorescence spectra display that the spherical silica surface has a great effect on the photoluminescence of the loaded CdS nanoparticles. In contrast to the CdS nanoparticles powder, the composite can exhibit the emission ascribed to the band gap transition when the CdS nanoparticles film is relatively thick. This phenomenon is probably due to an enhancement of the crystallinity of CdS nanoparticles induced by the silica spheres.