Interaction of copper nanoparticles with liposomes

The reduction of copper(II) ions in an aqueous dispersion of positively charged liposomes results in the formation of stable sols of a complex of copper nanoparticles with the surface of liposomes. The mean size (7 nm) and the narrow size distribution of metal nanoparticles are similar to those observed in the case of metal sol formation in polymer solutions. The labile character of bonds between nanoparticles and liposomes makes the latter able to compete with a linear polymer (poly-N-vinylpyrrolidone) in binding to nanoparticles. This ability is manifested in the independence of an almost even distribution of nanoparticles between these competitors from the sol preparation mode in a system including both poly(N-vinylpyrrolidone) macromolecules and liposomes. The evenness of the distribution indicates an approximately identical stability of complexes of copper nanoparticles with both competitors. The replacement of liposomes with poly(N-vinylpyrrolidone) macromolecules in the protective shields of nanoparticles is accompanied by the detachment of the nanoparticles from the surface, thereby allowing the measurement of their size and size distribution in the case where such measurements are impossible because of a high density of nanoparticles on the liposome surface.     

超声膜扩散法制备纳米银粒子

采用超声膜扩散(Ultrasound-assisted reaction method, UAMR)的方法, 以NaBH4还原溶液中的银离子, 在聚乙烯吡咯烷酮(PVP)为稳定剂的条件下, 制备出了平均粒度为4.7 nm的银纳米粒子. 与超声滴加法(Ultrasound-assisted dropping reaction method, UADR)相比, 超声膜扩散法制备出来的银纳米粒子的粒径小, 且尺寸分布较窄.     

微乳液和均匀沉淀耦合法制备CeO2纳米粒子

用W/O微乳液和草酸二甲酯均匀沉淀耦合法制备出单分散性好并具有较窄粒度分布的CeO2纳米粒子,测试了其形貌、粒径及粒径分布和晶体结构等特征.实验结果表明,表面活性剂的种类和反应物的相对初始浓度对产物平均粒径具有规律性的影响;随着焙烧温度升高,产物的平均粒径明显增大.     

Investigation of the formation of CuInS2 nanoparticles by the oleylamine route: comparison of microwave-assisted and conventional syntheses

The formation of copper indium disulfide nanoparticles via the oleylamine route using copper iodide, indium chloride, and elemental sulfur has been investigated by applying conventional thermal heating as well as microwave irradiation. Oleylamine thereby acts as a capping ligand as well as a solvent. In an initial set of experiments, the onset of the reaction was determined to be around 115 °C by an in situ X-ray study using Synchrotron radiation. Using comparatively low synthesis temperatures of 120 °C, it is already possible to obtain nanoparticles of 2-4 nm with both heating methods but with irregular shape and size distribution. By applying higher temperatures of 220 °C, more crystalline and larger nanoparticles were obtained with slight differences in crystallite size and size distribution depending on the synthesis route. The size of the nanoparticles is in the range of 3-10 nm depending on the heating time. Using microwave irradiation, it is possible to obtain nanoparticles in only 90 s of total synthesis time. Control experiments to probe a nonthermal microwave effect were carried out ensuring an identical experimental setup, including the heating profile, the stirring rate, and the volume and concentration of the solutions. These experiments clearly demonstrate that for the preparation of CuInS(2) nanoparticles described herein no differences between conventional and microwave heating could be observed when performed at the same temperature. The nanoparticles obtained by microwave and thermal methods have the same crystal phase, primary crystallite size, shape, and size distribution. In addition, they show no significant differences concerning their optical properties.     

Small-sized silver nanoparticles for studies of biological effects

The influence of the hydration extent, AOT and silver ion concentration on average particle size and size distribution in micellar solution of silver nanoparticles obtained by biochemical synthesis was investigated. Formation and stability of nanoparticles were controlled by measurements of optical absorption spectra. Particle sizes were determined by transmission electron microscopy. Combinations of varied parameters have been found, making it possible to prepare three micellar solutions of spherical silver nanoparticles with a different average size in the range 4.6–10.5 nm and narrow size distribution (the standard deviation does not exceed 2.5 nm). For the water dispersions prepared from such solutions by the specially developed procedure, possible applications for studies of size effects in the biological action of nanoparticles are also discussed.     

Sonochemical synthesis of cerium oxide nanoparticles-effect of additives and quantum size effect

Cerium oxide (CeO(2)) nanoparticles were prepared sonochemically, by using cerium nitrate and azodicarbonamide as starting materials, and ethylenediamine or tetraalkylammonium hydroxide as additives. The additives have a strong effect on the particle size and particle size distribution. CeO(2) nanoparticles with small particle size and narrow particle size distribution are obtained with the addition of additives; while highly agglomerated CeO(2) nanoparticles are obtained in the absence of additives. Monodispersed CeO(2) nanoparticles with a mean particle size of ca. 3.3 nm are obtained when tetramethylammonium hydroxide (TMAOH) is used as the additive and the molar ratio of cerium nitrate/azodicarbonamine/TMAOH is 1/1/1. Blue shifts of the absorption peak and the absorption edges of the products are observed in the UV-Vis absorption spectra as a result of the quantum size effect. The samples have been characterized using powder XRD, TEM, DLS, and absorption spectra.     

Synthesis of highly stable silver nanoparticles by photoreduction and their size fractionation by phase transfer method

In this report we demonstrate a green chemical approach for the synthesis of stable silver nanoparticles in aqueous medium using tyrosine as an efficient photoreducing agent. A narrow size distribution of silver nanoparticles can be achieved by this simple photoirradiation method without using any additional stabilizing agents or surfactants. Two different irradiation sources have been explored resulting in a different particle size distribution pattern in each case. Further, we show that starting from a polydisperse tyrosine synthesized silver nanoparticles sample, it is also possible to fractionate them into different size ranges. The size fractionation was achieved by a 2 stage phase transfer method employing different organic solvents. The nanoparticles synthesized were characterized using UV-vis spectroscopy, Transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques.     

Size evolution of gold nanoparticles in a millifluidic reactor

The size evolution of gold nanoparticles in a millifluidic reactor is investigated using spatially resolved transmission electron microscopy (TEM). The experimental data is supported by numerical simulations, carried out to study the residence-time distribution (RTD) of tracers that have the same properties as Au ions. Size and size distribution of the particles within the channels are influenced by the mixing zones as well as the RTD. However, the Au nanoparticles obtained show a broader size distribution even at the shortest investigated residence time of 3.53 s, indicating that in addition to surface growth reaction kinetics also plays an important role. The comparison of time resolved particle growth within the millifluidic channel with flask-based reactions reveals that the particle size can be controlled better within millifluidic channels. Overall, the results indicate potential opportunities to utilize easy to fabricate millifluidic reactors for the synthesis of nanoparticles, as well as as for carrying out time resolved kinetic studies.     

Kinetics of nucleation and growth of metal nanoparticles in the presence of surfactants

Numerical simulation has been performed for the process of nucleation and growth of nanoparticles in the presence of surfactants. Surfactant molecules are adsorbed on the surface of nanoparticles and decelerate their growth in supersaturated solutions. It has been assumed that nanoparticles are completely blocked after a certain degree of surface coverage is achieved, and they cease to grow. It has been demonstrated that, at low concentrations, surfactants influence the average size and the width of the size distribution of nanoparticles; i.e., the average particle size decreases and the distribution becomes narrower with the growth of surfactant concentration. At high concentrations, the effect of surfactants is more dramatic; namely, the particle size distribution becomes bimodal. At high surfactant concentrations, the periodic supply of a precursor, which serves as a source of monomers (metal atoms), may result in the formation of polymodal ensembles of the nanoparticles.     

粒径可控阳离子型聚苯乙烯纳米粒子的制备及表征

在采用阳离子型双子（gemini）表面活性剂作为乳化剂,不使用任何助乳化剂的条件下,通过改进微乳液聚合工艺制备了窄分布粒径可控的阳离子型聚苯乙烯（PS）纳米乳液。 改进微乳液聚合的主要特点是：大部分苯乙烯以预乳液的形式恒速滴入引发聚合的微乳液中,使用具有高乳化性能的gemini表面活性剂作为乳化剂能明显降低乳胶粒粒径。 实验结果表明,少量阳离子单体三甲基烯丙基氯化铵作为共聚单体能够明显减小Z均粒径、降低粒度分布,乳化剂用量、引发剂用量和反应温度均能影响制备乳胶粒的粒径及其粒度分布。 乳化剂和引发剂用量分别为苯乙烯质量的5%~10%和1.0%~1.5%、反应温度为70~75 ℃时,能够制备粒径小分布窄的阳离子型聚苯乙烯纳米粒子。 Z均粒径与苯乙烯质量之间的线性关系表明,Z均粒径可以通过苯乙烯用量来控制。 不同聚合工艺下制备的聚合物粒度分布曲线表明,改进微乳液聚合工艺（半连续预乳化工艺）在制备窄分布的聚合物纳米粒子方面具有很强的优越性。     

Preparation and characterization of silver nanoparticles by chemical reduction method

Silver nanoparticles were prepared by the reduction of AgNO(3) with aniline in dilute aqueous solutions containing cetyltrimethlyammonium bromide, CTAB. Nanoparticles growth was assessed by UV-vis spectroscopy and the average particle size and the size distribution were determined from transmission electron microscopy, TEM. As the reaction proceeds, a typical plasmon absorption band at 390-450nm appears for the silver nanoparticles and the intensities increase with the time. Effects of [aniline], [CTAB] and [Ag(+)] on the particle formation rate were analyzed. The apparent rate constants for the formation of silver nanoparticles first increased until it reached a maximum then decreased with [aniline]. TEM photographs indicate that the silver sol consist of well dispersed agglomerates of spherical shape nanoparticles with particle size range from 10 to 30nm. Aniline concentrations have no significant effect on the shape, size and the size distribution of Ag-nanoparticles. Aniline acts as a reducing as well as adsorbing agent in the preparation of roughly spherical, agglomerated and face-centered-cubic silver nanoparticles.     

异质哑铃型纳米颗粒合成中的关键因素(英文)

哑铃型纳米颗粒由一种包含强相互作用的异质结构成,它两端是不同物质的纳米颗粒.这两种不同功能的纳米颗粒紧密相连,形成一种哑铃形的外观.这种结构的纳米颗粒在电子、磁性、光学及催化等方面有着不同于单一组分纳米颗粒的独特性质,因此受到人们广泛关注.哑铃型纳米颗粒的这些独特性质是由两种物质交界面处的电子转移引起的,得益于较强的界面相互作用,两种物质都可以通过界面处的电子转移得到改良,使得这种结构的催化剂在较低温度下催化氧化有机废气时活性很高.以CO氧化反应为例,Au纳米颗粒通常情况下对该反应没有催化活性,但是被负载到金属氧化物上面以后,却表现出了很高的催化活性.这正是氧化物载体与Au纳米颗粒之间电子传输的结果.通常在核壳结构中,核心物质以及两种物质的交界面都被外壳所包裹,而哑铃型结构当中的两种物质的功能面以及它们之间活泼的交界面均可以充分地暴露在反应物中,从而极大提升了其催化效果.这种独特的结构优势也在疾病诊断与治疗中的多功能探针上得到了广泛应用.由于哑铃型结构的两种物质的纳米颗粒相对位置是固定的,当用作催化剂时可以发挥出很好的抗烧结性能,还可使这两种物质更协调地均匀分布.因此哑铃型结构催化剂不仅催化活性更高,而且在较高温度下具有较高的稳定性.哑铃型结构可以看作是独立纳米颗粒与核壳型纳米颗粒之间的一种中间状态,它通常是由一种物质的纳米颗粒在另一种种子颗粒上面经过外延生长得到的.这与核壳结构纳米颗粒的合成很相似,但是必须准确地控制成核过程,使得成核可以各向异性地发生在种子颗粒的某一个晶面上.而在核壳结构的合成中,这一成核过程是均匀分布的.所以在制备哑铃型结构纳米颗粒时,很重要的就是要促进非均质成核,同时抑制均相成核.由于哑铃型纳米颗粒的特殊结构,在制备时想要准确控制上述成核条件是非常困难的,所以到目前为止,仅有很少种类的物质可以被制成哑铃型结构,比如Au(Ag,Pt,Pd)-Fe3O4(Co3O4),Au-PbS(PbSe),FePt-CdS和Cu-Ag等,这些物质中大多数都是由贵金属纳米颗粒和磁性纳米粒子组成的.哑铃型纳米颗粒由于受限于物质种类,它在催化氧化方面的应用也被局限在了很少一部分气体上,如CO.而通过其它很多种催化剂已经可以在较低温度(甚至零下数摄氏度)下实现CO催化氧化.因此,哑铃型结构的优势在CO催化氧化中并不能得到很好利用和体现,而用于甲烷等一些在较低温度下更难氧化的气体的催化氧化尚未见报道.这正是由合成多种多样的哑铃型纳米颗粒的巨大困难所致.因此,找到合成哑铃型纳米颗粒的困难所在以及合成过程中的一些重要影响因素非常有意义,这将帮助我们使用更多的物质合成出一些新的哑铃型纳米颗粒,进而利用其高催化活性,使得更多难以氧化的气体在较低温度下被氧化.本文总结了合成哑铃型纳米颗粒时的多种影响因素,并介绍了相关的一些合成方法.种子颗粒的尺寸以及两种颗粒之间的尺寸比例可以影响制备过程中外延生长的可控性,颗粒尺寸以及两种颗粒的尺寸差别越小,反应越容易控制.反应温度和反应时间需要根据反应物的性质进行精确控制才可以得到合适的尺寸以及较好的粒径分布.而两种不同的物质最终能不能形成哑铃型结构则是由很多种因素决定的,比如反应溶剂的极性、两种物质之间的晶格错配度以及反应中所用乳化剂的含量.除此之外,合适的前驱体、氧化还原剂以及操作环境等都可以影响哑铃型纳米颗粒的合成结果     

Size-controlled synthesis of SnO2 nanoparticles using reverse microemulsion method

Tin oxide nanoparticles were prepared using an ionic surfactant (sodium dodecyl sulfate) and tin (IV) chloride as an inorganic precursor via the reverse microemulsion method. The size of the nanoparticles is controlled by variation of water-to-surfactant ratio. Eliminating of surfactant in prepared nanoparticles was confirmed by the infrared spectroscopy after sequential calcinations. Transmission electron microscopy, surface area, pore volume, average pore diameter, pore size distribution and X-ray diffraction results were used for evaluation of size distribution, shape and structure of prepared SnO₂ nanoparticles. Transmission electron micrographs confirmed that the obtained materials are spherical nanoparticles. The X-ray diffraction results show the crystalline phases of all samples are SnO₂ with tetragonal structured crystal. In addition, the X-ray diffraction and transmission electron microscopy data showed that the size of SnO₂ nanoparticles decreased with decreasing the water-to-surfactant ratio.     

电泳技术在纳米颗粒分离中的应用

合成纳米颗粒常在尺寸和形状方面具有广泛分布.在很多实验中,需要利用一定大小及形状的纳米颗粒的独特物理化学性质,因此,简便快速的纳米颗粒分离技术越来越受到诸多科学领域的重视.电泳技术以其高分辨率,被广泛用于多种生物大分子如核酸、蛋白质等的分离纯化.纳米颗粒在尺寸上与生物体中的蛋白复合物、细胞器和微生物等十分接近,考虑到带电纳米颗粒与生物分子在电场中的运动行为的相似性,运用电泳技术进行纳米颗粒的鉴定、分离和纯化是一种新的思路,并取得了良好的实验结果.本文主要介绍了琼脂糖凝胶电泳、毛细管电泳以及其他一些电泳技术在纳米颗粒分离中的研究进展.     

表面修饰Ag_2S纳米微粒的制备及其量子尺寸效应研究

采用同阳离子共沉淀法制备了DDP修饰的Ag2 S纳米微粒 ,其紫外—可见吸收光谱和荧光光谱表明DDP修饰的Ag2 S纳米微粒具有显著的量子尺寸效应 ,粒子尺寸分布较窄 ,粒子表面存在多种表面态能级。     

Optimization of dye-doped silica nanoparticles prepared using a reverse microemulsion method

Fluorescent labeling based on silica nanoparticles facilitates unique applications in bioanalysis and bioseparation. Dye-doped silica nanoparticles have significant advantages over single-dye labeling in signal amplification, photostability and surface modification for various biological applications. We have studied the formation of tris(2,2'-bipyridyl)dichlororuthenium(II) (Ru(bpy)) dye-doped silica nanoparticles by ammonia-catalyzed hydrolysis of tetraethyl orthosilicate (TEOS) in water-in-oil microemulsion. The fluorescence spectra, particle size, and size distribution of Ru(bpy) dye-doped silica nanoparticles were examined as a function of reactant concentrations (TEOS and ammonium hydroxide), nature of surfactant molecules, and molar ratios of water to surfactant (R) and cosurfactant to surfactant (p). The particle size and fluorescence spectra were dependent upon the type of microemulsion system chosen. The particle size was found to decrease with an increase in concentration of ammonium hydroxide and increase in water to surfactant molar ratio (R) and cosurfactant to surfactant molar ratio (p). This optimization study of the preparation of dye-doped silica nanoparticles provides a fundamental knowledge of the synthesis and optical properties of Ru(bpy) dye-doped silica nanoparticles. With this information, these nanoparticles can be easily manipulated, with regard to particle size and size distribution, and bioconjugated as needed for bioanalysis and bioseparation applications.     

硫化镉钠米微粒在聚合物网络中的组装

硫化镉钠米微粒在聚合物网络中的组装黄金满，杨毅，杨柏，刘式墉，沈家骢（吉林大学分子光谱与分子结构重点实验室、集成光电子国家重点实验室，长春，１３００２３）关键词组装，纳米微粒，离子交换，透射电子显微镜，电子衍射由于纳米半导体微粒的物理和化学性质介于分...     

反应条件对聚苯乙烯复合硫化铅纳米微粒粒度及分布的影响

用新的方法将ＰｂＳ纳米微粒复合在聚苯乙烯光学塑料中，并利用吸收光谱、小角Ｘ－光散射和透射电镜等方法研究了不同反应条件对复合的硫化铅（ＰｂＳ）纳米微粒粒度及分布的影响．结果表明，在一定范围内Ｈ２Ｓ的量和初始含铅聚合物浓度对纳米微粒的粒度影响很小，但对其粒度分布影响较大；当Ｈ２Ｓ与Ｐｂ２＋的摩尔比及初始含铅聚合物浓度均较大时，纳米微粒的粒度分布变宽．实验结果表明复合于聚苯乙烯中的ＰｂＳ的粒度分布是由溶液中反应决定的，本体聚合反应时对ＰｂＳ微粒的粒度分布影响很小．因此控制适当反应条件，可以得到粒度分布均一、分散均匀且透明性好的ＰｂＳ纳米微粒复合有机光学材料．     

One-step one-phase synthesis of monodisperse noble-metallic nanoparticles and their colloidal crystals

A variety of metallic nanoparticles with a narrow size distribution have been synthesized in a facile one-phase method in which amine-borane complexes are applied as reducing agents. It is particularly striking that large colloidal crystals with sizes up to tens of micrometers can directly form from the reaction mixtures without any further treatment. By using the synthetic route described, large-scale syntheses of both mono- and alloyed metallic nanoparticles with a narrow size distribution can be easily achieved.     

Nanoparticle precipitation in reverse microemulsions: particle formation dynamics and tailoring of particle size distributions

In this work, a detailed experimental analysis of the nanoparticle formation dynamics and the formation mechanism in a reverse microemulsion system is given. The precipitation of barium sulfate nanoparticles inside microemulsion droplets is investigated at the molecular scale with respect to the evolution of the particle size distribution and the particle morphology by an extensive transmission electron microscope (TEM) analysis. Different mixing procedures (feeding strategies) of two reactants, barium chloride and potassium sulfate, are evaluated concerning their ability for a tailored particle design under consideration of the complete particle size distribution (modality and polydispersity). It is shown that improved knowledge about the particle formation mechanisms, the dynamics, and the influence of the colloidal microemulsion structure could be used for a tailored design of particles,for example, controlled synthesis of nanoparticles with a bimodal particle size distribution by the application of a sophisticated feeding strategy.