Synthesis of aqueous CdTe quantum dots embedded silica nanoparticles and their applications as fluorescence probes

This paper presents the synthesis of aqueous CdTe QDs embedded silica nanoparticles by reverse microemulsion method and their applications as fluorescence probes in bioassay and cell imaging. With the aim of embedding more CdTe QDs in silica spheres, we use poly(dimethyldiallyl ammonium chloride) to balance the electrostatic repulsion between CdTe QDs and silica intermediates. By modifying the surface of CdTe/SiO₂ composite nanoparticles with amino and methylphosphonate groups, biologically functionalized and monodisperse CdTe/SiO₂ composite nanoparticles can be obtained. In this work, CdTe/SiO₂ composite nanoparticles are conjugated with biotin-labeled mouse IgG via covalent binding. The biotin-labeled mouse IgG on the CdTe/SiO₂ composite nanoparticles surface can recognize FITC-labeled avidin and avidin on the surface of polystyrene microspheres by protein-protein binding. Finally, the CdTe/SiO₂ composite nanoparticles with secondary antibody are used to label the MG63 osteosarcoma cell with primary antibody successfully, which demonstrates that the application of CdTe/SiO₂ composite nanoparticles as fluorescent probes in bioassay and fluorescence imaging is feasible.     

微乳法合成Pt/C、PtIr/C催化剂及其电化学性能表征

以碳纳米粉(XC-72R)作为载体,采用三种不同方法合成Pt/C负载型催化剂。利用X射线衍射(XRD)、透射电镜(TEM)、循环伏安法(CV)、恒电位测试(Potentiostatic)以及线性极化分析（Potentiodynamic polarization）等手段进行催化剂表征,结果表明,微乳法制得的负载型催化剂,活性组分的颗粒尺寸为5～10nm,且均匀地分散在载体表面,其电化学性能良好。而微乳法进一步制备的含不同比例的负载型的PtIr/C催化剂,其中以Pt85Ir15表现出更为较好的电化学综合性能。     

The Formation of Middle-Phase Microemulsions of Polar Oils

Middle-phase microemulsions exhibit the unique properties of an ultra-low interfacial tension and a bicontinuous structure formed from the water and oil components. New developments exploiting these properties are described. In designing such systems, it is important that the spontaneous transition of the oil droplets from Winsor II through Winsor III to the Winsor I state is brought about by diffusion or chemical reaction. The selection of the hydrophobic and lipophilic surfactants is critical when low-energy emulsification systems for highly polar oils are being developed.     

Monodisperse Co,Zn-Ferrite nanocrystals: Controlled synthesis,characterization and magnetic properties

Co_xZn_yFe_3−x−yO₄ ferrite (x=1 to 0; y=0 to1) nanocrystals have been synthesized by reverse microemulsion method. The nanocrystals are then comprehensively characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Field emission transmission electron microscopy (FETEM), and magnetic properties were measured by using Vibrating sample magnetometer. X-ray analysis showed that all the crystals were cubic spinel. The lattice constant increased with the increase in Zn substitution. FETEM reveals that particle size varies in the range from 3 to 6 nm. As the concentration of Zn increases the magnetic behavior varies from ferromagnetic at y=0 and 0.2 to superparamagnetic to paramagnetic at y=1. The Curie temperature decreases with increasing concentration of Zn.     

费托合成反应中纳米铁催化剂上La和Ba助剂的协同效应(英文)

Effect of promoters such as Barium and Lanthanum has been investigated on the conventional nanostructured iron catalyst in Fischer-Tropsch synthesis (FTS). The nanosized iron-based catalysts were prepared by a microemulsion method with the general formulation of 100Fe/4Cu, 100Fe/4Cu/2La, 100Fe/4Cu/ 1La/1Ba, and 100Fe/4Cu/2Ba. The phase, structure, and morphology of the catalysts were characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy, temperature-programmed desorption of CO2, and temperature- programmed reduction. The results indicated that the addition of promoters could improve the activity of Fe catalysts for FTS and WGS (water-gas shift reaction) and lower the gas fraction at the outlet. In addition, both Ba- and La-promoted Fe catalysts exhibit the highest activity due to the synergetic effect.     

The influence of composition and structure of water-in-oil microemulsions on activities of Iraqi Turnip peroxidase

The activity of the enzyme Iraqi Turnip peroxidase (ITP) is studied in a reverse microemulsion composed of chloroform, aqueous buffer, sodium dodecylsulfate (SDS) and alcohols of the homologous series 1-propanol to 1-hexanol through the measurements of absorbancy of the product of oxidation at the wavelength of 470 nm in the course of reactions. The ITP catalyzed reaction is the oxidation of guaiacol by hydrogen peroxide. Maximum enzyme activity was obtained at ω₀ (molar ratio of water to surfactant) = 8. It was found that the oxidation reaction obeyed Michaelis–Menten kinetics in the investigated concentration rang (0.08–0.8 mM) of the substrate, and the Michaelis constant K_m and maximal reaction rate V_m were determined. The enzyme inhibition caused by the alcohols in microemulsions is a consequence of both the solubility of the alcohols in the buffer and the flexibility of the interfacial film.     

Microelectrode Electrochemistry in Microemulsion Systems

Abstract

In this paper, we demonstrate the microelectrode electrochemistry of a simple electroactive probe (ferrocene) in SDS/n‐C₄H₉OH/H₂O microemulsion systems. The oxidation of ferrocene within the microemulsion environment was carried out at a Pt microelectrode using a three‐electrode assembly with a Pt wire acting as an auxiliary electrode and an Ag wire as the pseudo‐reference electrode. Excellent Nernstian electrochemical responses were observed. The well‐defined reversible electrochemical responses facilitated the measurement of the self‐diffusion coefficient of microemulsion droplets and introduced the possibility of probing the structural changes of microemulsion systems.     

Highly concentrated emulsified microemulsions as solvent-free plant protection formulations

Effective plant protection agents are readily available and well implemented in industry. However, delivery to the plant and application on the leaf are processes that still need to be optimized. Up to now plant protection formulations represent either emulsion or suspension concentrates that often contain environmentally harmful organic solvents and/or adjuvants. Emulsified microemulsions are hierarchically organized systems comprising emulsion droplets that confine a water-in-oil microemulsion. In the present contribution we show that emulsified microemulsions prepared from environmentally friendly components can be loaded with the plant-protection agent Fenpropimorph® up to 48 wt.% without organic solvent. The emulsion itself is highly concentrated, containing 60 wt.% of dispersed phase, and can be readily diluted with water for spraying in farming applications. Small-angle X-ray measurements reveal the existence of a water-in-Fenpropimorph® microemulsion confined inside the emulsion droplets. Dynamic light scattering shows that the emulsions prepared are monomodal, comprising droplet radii in the hundred nanometer range.     

水包油型微乳液相色谱分离激素类药物的影响因素

采用水包油型微乳液相色谱(MELC)分离了6种激素类药物(醋酸可的松、泼尼松龙、己烯雌酚、炔雌醇、醋酸氟轻松及黄体酮)。考察了微乳流动相的组成成分(包括表面活性剂的浓度、油相种类、有机添加剂种类)及固定相孔径等对分离的影响。实验得到的最佳分离条件: 色谱柱为Venusil ASB C18 (T)(粒径5 μm,孔径30 nm,250 mm×4.6 mm),微乳流动相为30 g/L十二烷基硫酸钠(SDS)-0.8%正辛烷-6.6%正丁醇,流速为0.8 mL/min,检测波长为254 nm,柱温为35 ℃。该方法可用于甾体药物及其制剂的分离鉴别以及快速测定。     

Microemulsion polymerization of styrene stabilized by sodium dodecyl sulfate and short‐chain alcohols

Styrene microemulsion polymerizations with different short‐chain alcohols [n‐C_iH_2i+1OH (C_iOH), where i = 4, 5, or 6] as the cosurfactant were investigated. Sodium dodecyl sulfate and sodium persulfate (SPS) were used as the surfactant and initiator, respectively. The desorption of free radicals out of latex particles played an important role in the polymerization kinetics. An Arrhenius expression for the radical desorption rate coefficient was obtained from the polymerizations at temperatures of 50–70 °C. The polymerization kinetics were not very sensitive to the alkyl chain length of alcohols compared with the temperature effect. The maximal polymerization rate in decreasing order was C₆OH > C₄OH > C₅OH. This was related to the differences in the water solubility of C_iOH and the structure of the oil–water interface. The feasibility of using a water‐insoluble dye to study the particle nucleation mechanisms was also evaluated. The parameters chosen for the study of the particle nucleation mechanisms include the cosurfactant type (C_iOH), the SPS concentration, and the initiator type (oil‐soluble 2,2′‐azobisisobutyronitrile versus water‐soluble SPS). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3199–3210, 2001