Synthesis of Colloidal Cobalt Nanoparticles with Controlled Size and Shapes

A method of producing high quality magnetic colloidal dispersions by the rapid pyrolysis of cobalt carbonyl in an inert atmosphere was employed to produce monodispersed, stabilized, defect-free -cobalt nanocrystals with spherical shapes and sizes ranging from 3 to 17 nm, as well as cubic and rod-like shaped particles. The size distribution and the shape of the nanocrystals were controlled by varying the surfactant composition (oleic acid, phosphonic oxides and acids), its concentration and the reaction temperature. These particles have been observed to produce 2D self-assemblies when evaporated at low rates in a controlled atmosphere. A combination of X-ray powder diffraction; transmission electron microscopy; and SQUID magnetometry has been used to characterize both the dispersed nanocrystals and the assembled superlattices.     

四苯基铁卟啉仿生催化丙烯环氧化合成环氧丙烷的研究

合成了四苯基铁卟啉并用于催化丙烯环氧化合成环氧丙烷,考察了共还原剂种类、催化剂浓度、共还原剂用量、反应时间、反应温度、反应压力对实验的影响。该反应适宜的条件为1.74×10~(-5)mol/L催化剂TPPFe~(Ⅲ)Cl;1.31×10~(-4)mol/L助催化剂3-吲哚乙酸;共还原剂丙烯醛,n(正丁醛)∶n(丙烯)=1∶1.2;溶剂二氯甲烷,n(二氯甲烷)∶n(丙烯)=15.45;反应温度98℃;反应压力1.65 MPa;反应时间1.8 h。在该条件下,丙烯的转化率为35.04%,环氧丙烷的收率和选择性分别达34.28%和97.83%。     

Hot-Wire Synthesis of Gold Nanoparticles

Gold nanoparticles were synthesized by a hot-wire generator at atmospheric pressure using a gold-platinum composite wire. At low gas flow velocities the nanoparticles were found to be agglomerates of partially sintered primary particles. By reducing the tube size via the insertion of a nozzle with a throat diameter of 3 mm, the hot-wire generator was found to produce small (<10 nm diameter) crystalline gold particles. Elemental and x-ray photoelectron spectroscopy analysis of the particles showed that they were composed of gold with no platinum impurity. Charging analysis of the “as-produced” nanoparticles showed that fewer than 10% of the particles were charged, but the charge fraction increased as the applied power increased, as did the ratio of negatively-to-positively-charged particles.     

Methanobactin-Mediated One-Step Synthesis of Gold Nanoparticles

Preparation of gold nanoparticles with a narrow size distribution has enormous importance in nanotechnology. Methanobactin (Mb) is a copper-binding small peptide that appears to function as an agent for copper sequestration and uptake in methanotrophs. Mb can also bind and catalytically reduce Au (III) to Au (0). In this study, we demonstrate a facile Mb-mediated one-step synthetic route to prepare monodispersed gold nanoparticles. Continuous reduction of Au (III) by Mb can be achieved by using hydroquinone as the reducing agent. The gold nanoparticles have been characterized by UV-visible spectroscopy. The formation and the surface plasmon resonance properties of the gold nanoparticles are highly dependent on the ratio of Au (III) to Mb in solution. X-ray photoelectron spectroscopy (XPS), fluorescence spectra and Fourier transform-infrared spectroscopy (FT-IR) spectra suggest that Mb molecules catalytically reduce Au (III) to Au (0) with the concomitant production of gold nanoparticles, and then, Mb statically adsorbed onto the surface of gold nanoparticles to form an Mb-gold nanoparticles assembly. This avoids secondary nucleation. The formed gold nanoparticles have been demonstrated to be monodispersed and uniform by transmission electron microscopy (TEM) images. Analysis of these particles shows an average size of 14.9 nm with a standard deviation of 1.1 nm. The gold nanoparticles are extremely stable and can resist aggregation, even after several months.     

Novel Two-Step Synthesis of Controlled Size and Shape Platinum Nanoparticles Encapsulated in Mesoporous Silica

Uniform shape and size platinum nanoparticles encapsulated in mesoporous silica (SBA-15) were prepared in the same solution by a novel two-step method. Platinum nanoparticles were prepared in aqueous solution of K₂PtCl₄, the reduction was carried out by bubbling hydrogen, the capping material was tri-block poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) copolymer. The mesoporous silica was synthesized using the same copolymer as template from tetraethyl orthosilicate by hydrolysis in acidic conditions. The Pt-nanoparticles-in-mesoporous-silica system was characterized by a combination of low-angle powder X-ray diffraction, transmission electron microscopy and N₂ porosimetry. The platinum nanoparticles are encapsulated in the mesopores and retained their size and morphology. It appears that this hybrid material should be a superior three-dimensional high-surface-area catalyst for selective platinum-catalyzed reactions.     

溶剂稳定的钯纳米颗粒的控制合成

以乙酸钯为前体、三缩四乙二醇为溶剂和还原剂,在不使用保护剂、适量无水乙酸钠存在下,60℃水浴加热4 min,乙酸钯还原得到溶剂稳定的粒径小、大小均一、分散性好的钯纳米颗粒,平均粒径为(3.51±0.49)nm。     

共沉淀法合成小粒径单分散Fe3O4纳米颗粒

研究以FeSO4·7H2O和FeCl3·6H2O为原料,NH3·H2O作为沉淀剂,采用共沉淀法制备纳米Fe3O4颗粒,利用IR（红外光谱）、XRD（X射线衍射）等表征手段对割得的纳米颗粒进行了表征。结果表明：制备的纳米Fe3O4粒子粒径较细,且粒径分布较窄。据此找出制备纳米Fe3O4粒子的最佳实验条件为：铁盐溶液浓度为0．5mol／L,沉淀剂溶液浓度为0．2mol／L,Fe^2＋：Fe^3＋：OH^-=1．00：1．00：6．00,反应温度为30℃。制备纳米Fe3O4粒子粒径在10-20mm,且分散性较好;通过XRD谱图可以得出产物为具有立方晶系的纳米Fe3O4粒子。     

Controlled Growth of Colloidal Gold Nanoparticles: Single-Crystalline versus Multiply-twinned Particles

Gold nanocrystals with well-defined shapes are becoming more crucial in application fields as diverse as catalysis, plasmonics, sensing, drug delivery, and therapeutics. To accomplish real applications on a large scale, a tight control over the size and geometry of the nanoparticles is essential. During the last decade, a new view has emerged: the planning of the properties of nanoparticles based on the control of their morphology. This rational design of particles with desired properties requires strategies to control the nucleation and growth processes. This review provides an overview of applications, properties, characterization, and procedures for the growth of nanoparticles with well-defined shapes, emphasizing the differences between the controlled growth of single-crystal and twinned gold nanoparticles.     

Biological Evaluation of Photodynamic Effect Mediated by Nanoparticles with Embedded Porphyrin Photosensitizer

Clinically approved photodynamic therapy (PDT) is a minimally invasive treatment procedure that uses three key components: photosensitization, a light source, and tissue oxygen. However, the photodynamic effect is limited by both the photophysical properties of photosensitizers as well as their low selectivity, leading to damage to adjacent normal tissue and/or inadequate biodistribution. Nanoparticles (NPs) represent a new option for PDT that can overcome most of the limitations of conventional photosensitizers and can also promote photosensitizer accumulation in target cells through enhanced permeation and retention effects. In this in vitro study, the photodynamic effect of TPP photosensitizers embedded in polystyrene nanoparticles was observed on the non-tumor NIH3T3 cell line and HeLa and G361 tumor cell lines. The efficacy was evaluated by viability assay, while reactive oxygen species production, changes in membrane mitochondrial potential, and morphological changes before and after treatment were imaged by atomic force microscopy. The tested nanoparticles with embedded TPP were found to become cytotoxic only after activation by blue light (414 nm) due to the production of reactive oxygen species. The photodynamic effect observed in this evaluation was significantly higher in both tumor lines than the effect observed in the non-tumor line, and the resulting phototoxicity depended on the concentration of photosensitizer and irradiation time.     

One Pot Synthesis of Large Gold Nanoparticles with Triple Functional Ferrocene Ligands

In biomedical, toxicological, and optoelectronic applications, the size of nanoparticles is one of the decisive factors. Therefore, synthesis of nanoparticles with controlled sizes is required. The current methods for synthesis of larger gold nanoparticles (GNPs, ~200 nm) are complex and tedious, producing nanoparticles with a lower yield and more irregular shapes. Using ferrocene as a primary reducing agent and stabilizer, sodium citrate as a dispersant, and sodium borohydride as an accessory reducing agent, GNPs of 200 nm were synthesized in a one pot reaction. Besides the roles of reducing agent and GNP stabilizer, ferrocene also served a role of quantitative marker for ligand loading, allowing an accurate determinate of surface ligands.     

四(3,4-二羟基苯基)卟啉化合物的合成试验研究

卟啉类试剂是一种高灵敏性的分析试剂,在分析化学、医学及生物化学等领域都有着极其广泛的用途,近年来一直得到广大科学研究者的关注。本文通过设计合成路线经过试验成功合成了3,4-二羟基苯基卟啉化合物,引入的羟基解决了普通卟啉化合物水溶性差的问题,同时分析探索了其合成路线和主要影响因素。     

一种新型稀土纳米粒子的可控合成

纳米粒子的粒径与其应用联系紧密,研究发现六方相稀土纳米晶的上转换效率比立方相高,为可控合成一定粒径、六方相的稀土纳米粒子,文章采用溶剂热法,以Na YF4为基质,掺入一定比例在稀土元素Yb及Er,并改变反应温度、稀土掺杂量等影响因素,得出在300℃条件下,合成分散性好的六方相稀土纳米粒子。为稀土纳米粒子的可控合成提供依据,同时对研究稀土纳米材料的应用提供参考。     

合成不同粒径大小的金纳米粒子的分析研究

金属纳米粒子中金纳米粒子作为其中最重要的一员,由于其具有独特的催化性能、光学性能、导电性能,使其在生物传感~([1])、催化、药物载体、基因芯片~([2])等众多领域有着广泛的应用。纳米金在各个应用中控制其特定形貌、尺寸大小、空间结构具有十分重要的意义,但又面临一定的合成挑战。本文针对合成不同粒径的纳米金采用了不同的合成方法,成功地合成出不同粒径大小的纳米金。     

以酸解TEOS为硅源合成可控孔径和粒径NaP分子筛

利用盐酸预处理TEOS得到的硅凝胶为硅源,铝酸钠为铝源,通过水热合成法制备了一种晶粒尺寸和孔径大小可控的NaP分子筛.利用不同时间酸解TEOS得到的硅凝胶合成NaP分子筛,但合成的样品杂晶较多且形貌不规整;采用正交试验,通过调节晶化时间、晶化温度、溶液pH值和水硅比,以达到样品提纯、形貌规整的目的.对样品进行SEM、XRD、N2物理吸附等表征,分析样品的形貌、结晶度和孔径分布等.并对样品进行铜离子吸附性能测试,得到NaP分子筛对Cu2+的有效去除率为98.9％.利用预先酸解TEOS得到的硅凝胶合成NaP分子筛的方法,为工业污水净化提供一定的理论依据及指导.     

凝胶网格控制合成纳米ZnO及其光催化活性

以明胶为反应介质,采用凝胶网格控制合成法制备了单分散球形纳米ZnO光催化剂.利用TG-DTA、XRD、TEM、BET、UV-Vis、HPLC等测试手段对制备过程、样品的结构和性能进行了研究,探讨了明胶浓度、煅烧温度对产物粒径和光催化活性的影响.结果表明:利用凝胶网格控制合成法不仅能够控制纳米微粒的形状和大小,而且可防止沉淀物相互聚集和团聚.以染料罗丹明B溶液为目标降解物,1 h的降解率为99.9%,最佳光催化剂的合成条件:13%明胶浓度、350℃煅烧2 h.     

天然产物绿色合成小尺寸纳米银及抗菌性

利用液相化学还原法,以硝酸银作前驱体,采用天然产物壳聚糖和葡萄糖分别作稳定剂和还原剂制备了小尺寸的球形纳米银(AgNPs)。运用紫外-可见分光光度计(UV-vis)、透射电子显微镜(TEM)和X射线衍射(XRD)技术对一系列AgNPs样品进行了表征,并考察了稳定剂、前驱体和还原剂的浓度、pH、反应温度和时间等制备条件对AgNPs成核或生长过程的影响。通过调节制备条件可调控AgNPs的尺寸分布,得到粒径分别为(3±1)nm、(6±2)nm和(9±3)nm分散均匀且稳定的AgNPs。采用OD600法对AgNPs的抗菌性进行了测试,结果表明,AgNPs对大肠杆菌(E.coil)和金黄色葡萄糖球菌(S.aureus)都有很好的抑制作用。     

Commercial Supported Gold Nanoparticles Catalyzed Alkyne Hydroamination and Indole Synthesis

Commercial gold nanoparticles supported on titanium dioxide (TiO₂) were found to be a highly efficient catalyst for alkyne hydroamination. Terminal alkynes could easily undergo intermolecular hydroamination with low catalyst loadings (0.2 mol% Au) under solvent‐free conditions. Indoles were efficiently synthesized using microwave heating through intramolecular hydroamination.