Synthesis of anisotropic gold nanoparticles in a water-soluble polymer

Anisotropic gold nanoparticles have been synthesized by a UV irradiation technique through the interaction of HAuCl₄ and a stabilizing agent, poly (vinyl pyrrolidone) (PVP). The effect of irradiation time on the size and shape of gold nanoparticles was investigated by UV-visible spectroscopy and Transmission Electron Microscopy (TEM). The absorption spectra of all samples show a broad band with the characteristic surface plasmon resonance (SPR) peak visible at around 530 nm. The presence of an additional low intensity absorption peak at a longer wavelength suggests the presence of non-spherical nanoparticles. The TEM measurements show evidence of particle shapes such as spheres, hexagons, decahedrons and truncated triangles as the reaction proceeded from 5 min to 24 h. The variation in particle shape is probably due to the effect of the reduced gold to PVP ratio as the reaction proceeds.     

水溶性LaF3：Eu荧光纳米粒子的合成及表征

以稀土氯化物、NaF和柠檬酸钠为反应原料,水浴加热合成水溶性LaF3: Eu荧光纳米粒子,考察了反应温度、溶液pH值和反应原料配比等对合成粒子荧光性能的影响,给出了最佳反应条件.红外光谱实验证明,合成粒子表面包覆了柠檬酸根.XRD测试表明,合成粒子是单一相LaF3晶体,掺杂Eu3 替代La3 进入LaF3晶格,晶粒径为8.3nm.TEM实验表明,合成粒子粒度分布较均匀.该合成方法简便易行,合成粒子的水溶液荧光强度较高且荧光强度稳定,有望将其和生物分子连接,进行生物分子的检测.     

Synthesis and optical properties of TiO2 nanoparticles

Ultrafine TiO₂ particles have been synthesized successfully by a facile gas flame combustion method. The synthesized sample is characterized by X-ray diffraction (XRD), transmission electron micrograph (TEM), Fourier transform infrared (FTIR), and photoluminescence (PL) spectroscopy. The as-prepared TiO₂ nanoparticles appear to be a single anatase crystalline phase and the diameter is about 9 nm. Besides a sharp emission at 398 nm originating from the radiative annihilation of excitions, a weak broad band at about 434 nm from the defect-related emission is also discussed.     

Synthesis and enhanced electrochemical properties of pod-shaped gold/silica nanoparticles

Pod-shaped gold/silica nanoparticles (PGSNPs) were prepared using perfluorooctanoic acid (PFOA) and cetyltrimethylammonium bromide (CTAB) as cotemplates. The PGSNPs were utilized to explore a novel biosensor through coupling myoglobin (Mb) with chitosan (Chi). Compared with Mb-Chi-PSNPs (pod-shaped silica nanoparticles)/GC modified electrode, Mb-Chi-PGSNPs/GC electrode exhibited a pair of much stronger redox peaks at − 0.28 V (vs. Ag/AgCl). Moreover, facilitated direct electron transfer of the metalloenzymes with smaller peak-to-peak separation (ΔEp) of about 46 mV was acquired on the PGSNPs-based enzyme electrode. The PGSNPs-based biosensor demonstrated significant electrocatalytic activity for the reduction of hydrogen peroxide with a wide linear range (1-540 µM) and high sensitivity (661 mA cm^− 2 M^− 1). Together, the Mb-Chi-PGSNPs film is one of ideal candidate materials for direct electrochemistry of redox proteins, and may find potential applications in biomedical, food, and environmental analysis and detection.     

Synthesis and properties of hollow silica nanoparticles

Hollow nanoparticles of silicon dioxide (SiO₂) have been obtained using Cu/SiO₂ core-shell nanoparticles as precursors. An original technique based on heating the precursor nanoparticles to T = 400°C followed by a nanochemical reaction of copper oxide separation from hollow silica particles has been proposed and implemented for the first time. The obtained hollow SiO₂ nanoparticles have been studied by transmission electron microscopy. Mechanisms involved in the formation of hollow silica nanoparticles are discussed.     

Synthesis and antibacterial properties of silver nanoparticles

Nanometer sized silver particles were synthesized by inert gas condensation and co-condensation techniques. Both techniques are based on the evaporation of a metal into an inert atmosphere with the subsequent cooling for the nucleation and growth of the nanoparticles. The antibacterial efficiency of the nanoparticles was investigated by introducing the particles into a media containing Escherichia coli. The antibacterial investigations were performed in solution and on petri dishes. The silver nanoparticles were found to exhibit antibacterial effects at low concentrations. The antibacterial properties were related to the total surface area of the nanoparticles. Smaller particles with a larger surface to volume ratio provided a more efficient means for antibacterial activity. The nanoparticles were found to be completely cytotoxic to E. coli for surface concentrations as low as 8 microg of Ag/cm2.     

Synthesis and optical properties of erbium-doped BaF2 nanoparticles

Erbium-doped BaF₂ nanoparticles were prepared using the ultrasonic surge method. The particles were characterized by X-ray diffraction, transmission electron microscope, photoluminescence and absorption. The results show that when Er³⁺ ions were introduced into the BaF₂ lattice, cubic fluorite-type Ba_1−xEr_xF_2+x solid solution, x = 0.42 was formed. Furthermore, the crystalline phase of Ba_1−xEr_xF_2+x solid solution was largely influenced by the annealing temperature.     

Synthesis and photoluminescence properties of hydrophilic ZnS nanoparticles

ZnS nanoparticles with an average diameter of 10 nm were synthesized by a solvothermal method under easily controlled and mild conditions. A composite surfactant for the preparation of ZnS nanoparticles was reported in order to improve the hydrophilicity. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize ZnS nanoparticles. The selected area electron diffraction (SAED) pattern indicated that ZnS was of high crystalline. The photoluminescence (PL) properties and water solubility of ZnS were investigated too. The photoluminescence characteristics indicated that ZnS nanoparticles exhibited a strong luminescent at 450 nm. Results of the contact angle demonstrated that the hydrophilicity has been improved greatly.     

Synthesis and microwave absorption properties of magnetite nanoparticles

Nanoparticles of Fe3O4 with various sizes were synthesized from FeCl3 x 6H2O, FeCl2 x 4H2O and NaOH by coprecipitation process. The crystal structure, morphology, particle size and magnetic property of the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). It was found that the molar ratio of ferrous to ferric played an important role in the formation of Fe3O4 nanoparticles. The particle mean diameter swelled from approximately 10 to approximately 20 nm with the molar ratio range from 1:2 to 6:1. The saturation magnetization and the coercivity increased correspondingly. The complex permittivity epsilon(r) and permeability mu(r) of the Fe3O4 mixture with paraffin were measured using vector network analysis. Values of epsilon(r), and mu(r) were used to determine the reflection loss at various sample thicknesses, based on a model of microwave absorbing layer backed by a metal plate. The minimal reflection loss or the dip shifts to a lower frequency region with increasing thickness. When the thickness is 5 mm, the minimal reflection loss of Fe3O4 synthesized with the molar ratio of 6:1 and paraffin wax composites reaches -35.1 dB at 5.2 GHz and -30.2 dB at 17.6 GHz, respectively. The minimal reflection loss is attributed to the thickness of the absorber approximates an odd number multiple of a quarter of the propagation wavelength.     

Synthesis and properties of amorphous SiO2 nanoparticles

We have studied the synthesis of amorphous silica nanoparticles through fluorination processing of quartz sand. The results demonstrate that synthesis conditions influence the physicochemical properties of the resultant amorphous silica. We have obtained silica-containing powders 17 to 89 nm in average particle size and 92 to 508 m²/g in specific surface area.     

Synthesis and electrochromic properties of a highly water-soluble hyperbranched polymer viologen

A highly water-soluble hyperbranched polymer with viologen units (HB-1) was synthesized for application to electrochromic (EC) display. Electrochemical and spectroscopic properties of HB-1 were evaluated by absorption spectra and cyclic voltammetry. They were compared with those of a low molecular weight viologen molecule (1). We fabricated a simple EC window by a thin (300-500 nm) solid film of HB-1 and an electrolyte solution to demonstrate the EC behavior. By successively applying opposite bias voltages to it, reversible color changes between colorless and purple were observed with good contrast, whereas blue color was observed for 1 upon reduction. The colored state in HB-1 was ascribed to the generation of radical cation dimer species of viologen units due to high local concentrations in HB-1. When the bias was turned off after achieving the colored state, no fading was observed in the EC window. This result indicates that the radical cation dimer species of HB-1 in solid films were stable against disproportionation or reaction with oxygen even though no active protection was made in this EC window. Since the present EC device has such a memory effect, bias voltage is needed in writing and erasing processes alone, which is very useful in practical applications.     

锰锌铁氧体纳米粒子的制备和磁性能研究

以金属离子的硫酸盐溶液和氨水溶液为原料,采用水热法制备了粒径为6～16nm的锰锌铁氧体纳米粒子.采用XRD、TEM、TGA和VSM等方法对产物以及产物的磁性能进行了表征.结果表明,锰锌铁氧体(Mn1-xZnxFe2O4)的居里温度随着锌的相对含量x的增加而单调的降低.锰锌铁氧体的磁化强度先随着锌的相对含量x的增加而增大,当锌的相对含量＞0.6时,磁化强度随着锌的相对含量x的增加而减小.测量了锰锌铁氧体磁流体的饱和磁化强度,计算了锰锌铁氧体(Mn0.4Zn0.6Fe2O4)纳米粒子的磁矩,其值为1.01×10-19A·m2.     

多响应性聚合物微球的制备与光学性质研究

通过分散聚合法合成了形态规则、平均粒径在370nm左右、粒径分布均匀的聚（N-异丙基丙烯酰胺甜丙烯酸（P（NIAM-co-AAc））交联型聚合物微球．在，此基础上选择不同浓度的Tb（Ⅲ）离子与P（NIPAM-co-AAc）微球进行复配，制备了P（NIPAM-co-AAc）-Yb（Ⅲ）的复配微球．通过紫外光谱和荧光光谱对复配微球的表征发现：该复配微球具有温敏性和pH响应性：P（NIPAM-CO-AAc）微球和Tb（Ⅲ）之间发生了有效的能量传递，明显增强了Yb（Ⅲ）的特征荧光发射．     

Synthesis and magnetic properties of shuriken-like nickel nanoparticles

Shuriken-like nickel nanoparticles were successfully synthesized by a thermal decomposition method at 200 °C with Nickel(II) acetylacetonate (Ni(acac)₂) as the precursor and oleylamine (OAm) as the solvent and reductant, respectively. The phase structures, morphologies and sizes, and magnetic properties of the as-synthesized nickel products were characterized in detail by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). Some key reaction parameters, such as the reaction time, reaction temperature and surfactants, have important influence on the morphology of the final products. XRD pattern indicated that the products are well-crystallized face-centered cubic (fcc) nickel phase. SEM images demonstrated that the nickel nanoparticles are shuriken-like morphology with average size around 150 nm. The mechanism of shuriken-like Ni nanoparticles (NPs) is proposed. The magnetic hysteresis loops of shuriken-like and spherical nickel products illustrated the ferromagnetic nature at 300 K, indicating its potential applications in magnetic storage.     

Synthesis of water-soluble urethane acrylate anionomers and their ultra-violet coating properties

Water-soluble and ultraviolet (UV)-curable urethane acrylate anionomers containing dimethylolpropionic acid (DMPA) were synthesized with varying molecular weight of soft segment and degree of neutralization. The ion group incorporated was confirmed by ¹H-NMR and ¹³C-NMR spectra. In viscosity measurements, the enhancement of viscosity was achieved with increasing of ionic strength or pH of the solution. However, when the molecular weight of soft segment was high, the viscosity little changed for given parameters. This indicates that the strong hydrophobic interaction caused by the long soft segment made the anionomer chain aggregate. The UV coating properties of urethane acrylate anionomer films were depended on the molecular weight of soft segment and the degree of neutralization. For the films of high ion content and low molecular weight of soft segment, the tensile strength had a tendency toward increasing, on the contrary, for the films of low ion content and high molecular weight of soft segment, the tensile strength displayed reverse tendency. However, compared with general urethane acrylate films, overall coating properties were significantly improved. This was believed that the ionic groups acted as reinforcing filler by means of the phase separation from the crosslinked urethane acrylate network.     

Cytotoxicity and photocytotoxicity of structure-defined water-soluble C60/micelle supramolecular nanoparticles

Well-defined, water-soluble C(60)/micelle hierarchical colloids with varied amounts of C(60) sitting on the surface of micellar cores were prepared via the self-assembly of PS-b-PDMA block copolymer micelles and C(60). The composites can generate a significant amount of reactive oxygen upon irradiation with red light. Cell studies showed that the colloids were either strongly associated with, or internalized by, the cells after 2 h incubation, but did not show obvious toxicity in the dark. In contrast, efficient cell killing was observed when the colloid-incubated cells were exposed to red light. This indicates that the supramolecular colloids are promising as photosensitizers for photodynamic cancer therapy.     

Barium hexaferrite nanoparticles: Synthesis and magnetic properties

Carbon combustion synthesis is applied to rapid and energy efficient fabrication of crystalline barium hexaferrite nanoparticles with the average particle size of 50-100 nm. In this method, the exothermic oxidation of carbon nanoparticles with an average size of 5 nm with a surface area of 80 m²/g generates a self-propagating thermal wave with maximum temperatures of up to 1000 °C. The thermal front rapidly propagates through the mixture of solid reactants converting it to the hexagonal barium ferrite. Carbon is not incorporated in the product and is emitted from the reaction zone as a gaseous CO₂. The activation energy for carbon combustion synthesis of BaFe₁₂O₁₉ was estimated to be 98 kJ/mol. A complete conversion to hexagonal barium ferrite is obtained for carbon concentration exceeding 11 wt.%. The magnetic properties H_c∼3000 Oe and M_s∼50.3 emu/g of the compact sintered ferrites compare well with those produced by other synthesis methods.     

CdS/ZnO核壳结构纳米微粒的合成及其发射光谱研究

采用单分子前驱体热分解的方法合成了单分散CdS纳米晶,以CdS纳米晶作为核,在CTAB辅助下,对其表面进行修饰,荧光光谱表明CdS/ZnO核壳结构被成功合成。考查了温度对包覆的影响,结果表明,随着温度的升高晶体结晶越好,包覆越来越完全,ZnO包覆在CdS纳米晶的表面而掩盖了CdS纳米晶的缺陷,使得缺陷发光减弱而带隙发光增强。     

Luminescent stability of water-soluble PbS nanoparticles

Thiol-capped PbS semiconductor nanoparticles (NPs) stabilized with a mixture of 1-thioglycerol/dithioglycerol (TGL/DTG) were colloidally prepared at room temperature. UV–vis spectroscopy and photoluminescence (PL) spectra showed an obvious red-shift in both the absorption shoulder and PL peak with the increase of DTG/Pb molar ratio. Room temperature photoluminescence quantum efficiency (PLQE) of freshly prepared PbS NPs (7–11%) remained higher than 5% upon aging for 3 weeks when the NPs were stored in an ice-bath in the dark, and higher than 5% for at least 5 weeks when additional DTG ligand was introduced into the nanoparticle solution every 2 weeks. The combination of reasonable room temperature quantum efficiency and strong, stable luminescence covering the 1.3 μm telecommunication window make these NPs promising materials in optical devices and telecommunications.

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Synthesis and properties of a water-soluble ionic conjugated polymer with carboxylic acids

A new water-soluble ionic conjugated polymer, poly[N-(carboxymethyl)-2-ethynylpyridinium bromide], was prepared by the activated polymerization of 2-ethynylpyridine by using bromoacetic acid. This polymerization proceeded well in mild reaction conditions without any additional initiator or catalyst. The polymer structure was characterized by various instrumental methods to have a conjugated polymer backbone system with the designed functional groups. The photoluminescence spectrum of polymer showed that the PL peak is located at 603 nm corresponding to the photon energy of 2.06 eV. The cyclovoltammograms of polymer exhibited the irreversible electrochemical behaviors between the oxidation and reduction peaks. The oxidation current density of polymer versus the scan rates is approximately linear relationship in the range of 30 mV/sec-150 mV/sec. It was found that the kinetics of the redox process of polymer is almost controlled by the reactant diffusion process from the oxidation current density of polymer versus the scan rates.