Aqueous Synthesis of Water-Soluble Citrate-Modified Cadmium Selenide/Cadmium Sulfide/Zinc Sulfide Quantum Dots

Water-soluble cadmium selenide/cadmium sulfide/zinc sulfide core/shell/shell quantum dots were synthesized in aqueous solution using trisodium citrate as modifier. The crystal structure, morphology, component, and spectral properties of cadmium selenide/cadmium sulfide/zinc sulfide core/shell/shell quantum dots were characterized by X-ray power diffraction, transmission electron microscope, energy dispersive X-ray analysis, infrared spectrum, ultraviolet–visible absorption spectrum, and fluorescence spectrum. The results show that the spherical citrate-modified cadmium selenide/cadmium sulfide/zinc sulfide core/shell/shell quantum dots with diameter around 3.6 nm belong to the cubic zinc blende structure. The citrate-modified cadmium selenide/cadmium sulfide/zinc sulfide core/shell/shell quantum dots show a narrow, symmetric, and strong fluorescence emission spectrum band with narrow full width at half maximum of 53 nm, and the fluorescence quantum yield can reach up to 37.3%. The high-quality citrate-modified cadmium selenide/cadmium sulfide/zinc sulfide core/shell/shell quantum dots with good fluorescence properties have potential for application in biological fluorescence analysis.     

Aqueous Synthesis of Water-Soluble L-Cysteine-Modified Cadmium Sulfide Doped with Silver Ion/Zinc Sulfide Nanocrystals

The water-soluble silver ion-doped cadmium sulfide nanocrystals were synthesized by a co-precipitation technique in aqueous solution using L-cysteine as surface modifier, and then L-cysteine-modified cadmium sulfide doped with silver ion/zinc sulfide core/shell nanocrystals were prepared by zinc sulfide epitaxial coated on surface of silver ion-doped cadmium sulfide nanocrystals. The crystal structure, morphology, and spectral properties of cadmium sulfide doped with silver ion/zinc sulfide nanocrystals were characterized by X-ray power diffraction, transmission electron microscope, infrared spectrum, and photoluminescence spectrum. The results show that the photoluminescence quantum yield of cadmium sulfide doped with silver ion/zinc sulfide nanocrystals is improved greatly after doped with silver ion and coated with zinc sulfide shell. The cysteine modified on the surface of cadmium sulfide doped with silver ion/zinc sulfide nanocrystals renders the nanocrystals water-soluble and biocompatible.     

Investigation of Novel Quantum Dots/Proteins/Cellulose Bioconjugate Using NSOM and Fluorescence

We investigated the engineered bioconjugate of cadmium selenide core/zinc sulfide shell, (CdSe)ZnS, quantum dots (QDs) with genetically modified proteins using fluorescence spectroscopy, near-field scanning optical microscopy (NSOM) and spectroscopy (NSOS). The protein polymer was allowed to self-assemble to the bacterial microcrystalline cellulose surface through the cellulosic binding domain. Results from the sample containing the QDs/protein/cellulose assemblies suggest that QDs were arrayed along the cellulose surface. The spectroscopic change of spectroscopic properties of the QDs upon bioconjugation, indicating the interaction among the immobilized QDs and between the constructed protein and QDs.     

单核/双壳结构CdSe/CdS/ZnS纳米晶的合成与发光性质

以巯基乙酸为稳定剂,在水溶液中合成了单核/双壳结构的CdSe/CdS/ZnS纳米晶。在内核CdSe和外壳ZnS之间的内壳CdS作为晶格匹配调节层,能够很好的改善核/壳界面处的性能,而且,最外层ZnS能够最大程度地使激子受限。用TEM和XPS对纳米晶进行了表征,并且用光致发光光谱和吸收光谱对不同核壳结构的纳米晶的发光性能进行了比较,结果表明单核/双壳结构的纳米晶具有更加优异的发光特性。     

Growth and Physical Properties of CdS/TiO_2 Bilayer by Plasma-Based Method

The titanium oxide(TiO_2) nanotubes have attracted attention for their use in dye-sensitized solar cells as photoanode. In this study semiconducting cadmium sulfide(CdS) nanoparticles are grown on top opened TiO_2 nanotubes arrays by radio-frequency magnetron sputtering. X-ray diffraction, scanning electron microscopy,transmission electron microscopy and diffuse reflection spectra are used to study structural, morphological and optical properties of the CdS/TiO_2 bilayer.     

Inhibition effects of protein-conjugated amorphous zinc sulfide nanoparticles on tumor cells growth

In this article, a facile and environmentally friendly method was applied to fabricate BSA-conjugated amorphous zinc sulfide (ZnS) nanoparticles using bovine serum albumin (BSA) as the matrix. Transmission electron microscopy analysis indicated that the stable and well-dispersed nanoparticles with the diameter of 15.9 ± 2.1 nm were successfully prepared. The energy dispersive X-ray, X-ray powder diffraction, Fourier transform infrared spectrograph, high resolution transmission electron microscope, and selected area electron diffraction measurements showed that the obtained nanoparticles had the amorphous structure and the coordination occurred between zinc sulfide surfaces and BSA in the nanoparticles. In addition, the inhibition effects of BSA-conjugated amorphous zinc sulfide nanoparticles on tumor cells growth were described in detail by cell viability analysis, optical and electron microscopy methods. The results showed that BSA-conjugated amorphous zinc sulfide nanoparticles could inhibit the metabolism and proliferation of human hepatocellular carcinoma cells, and the inhibition was dose dependent. The half maximal inhibitory concentration (IC50) was 0.36 mg/mL. Overall, this study suggested that BSA-conjugated amorphous zinc sulfide nanoparticles had the application potential as cytostatic agents and BSA in the nanoparticles could provide the modifiable site for the nanoparticles to improve their bioactivity or to endow them with the target function.     

Core/shell structured ZnO/SiO2 nanoparticles: Preparation, characterization and photocatalytic property

ZnO nanoparticles were prepared by a simple chemical synthesis route. Subsequently, SiO₂ layers were successfully coated onto the surface of ZnO nanoparticles to modify the photocatalytic activity in acidic or alkaline solutions. The obtained particles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectrometry (EDS) and zeta potential. It was found that ultrafine core/shell structured ZnO/SiO₂ nanoparticles were successfully obtained. The photocatalytic performance of ZnO/SiO₂ core/shell structured nanoparticles in Rhodamine B aqueous solution at varied pH value were also investigated. Compared with uncoated ZnO nanoparticles, core/shell structured ZnO/SiO₂ nanoparticles with thinner SiO₂ shell possess improved stability and relatively better photocatalytic activity in acidic or alkaline solutions, which would broaden its potential application in pollutant treatment.     

银/二氧化钛核壳纳米颗粒对碲化镉纳米晶的荧光增强研究

利用新合成的复合纳米结构银/二氧化钛核壳纳米颗粒,研究了金属银纳米颗粒对碲化镉纳米晶层荧光的增强情况.结果表明,这种新型复合金属纳米结构能极大地增强发光纳米晶层的荧光强度.银/二氧化钛核壳纳米颗粒是以水合肼、硝酸银和四异丙氧基钛为原材料,利用胶体化学法在水溶液中合成.透射电子显微镜图片表明这种新合成的银/二氧化钛纳米材料基本上呈球形,有较为明显的核壳结构,中间黑色的核是银纳米颗粒,外层颜色较浅部分是二氧化钛壳层.另外,包裹二氧化钛壳层后,银纳米颗粒的表面等离子吸收带从409 nm红移至430 nm,也证实了这种新型核壳纳米材料的形成.将此合成方法得到的银/二氧化钛纳米颗粒和碲化镉纳米晶用旋转涂覆方法进行直接组合后,得到了银纳米颗粒对碲化镉纳米晶荧光的明显增强,并对其增强的物理过程进行了讨论.这种能够增强荧光团发光的新型复合银纳米结构将在发光器件、荧光成像、生物探测等方面具有一定的应用价值.     

Synthesis and coating methods of biocompatible iron oxide/gold nanoparticle and nanocomposite for biomedical applications

This detailed review presents an overview of current research on the synthesis, surface modification, and applications of Iron oxide (Fe₃O₄) nanoparticles and iron oxide/gold (Fe₃O₄/Au) nanocomposites. The different synthesis techniques of Fe₃O₄ with various basic organic and inorganic modifications are presented. The applicability and role of inorganic and organic coating on iron oxide/gold core/shell schemes were explored. The trade-off between choices for surface functionalization related to specific applications such as imaging contrast agent, drug delivery carrier and therapeutic device using iron oxide/gold core/shell was also elaborated. The versatility of combining iron oxide/ and gold as nanocomposite as the choice for biomedical application is demonstrated in MRI, CT scan, drug delivery, biosensors, and hyperthermia application.     

液相激光烧蚀合成ZnO及Zn/ZnO纳米颗粒及其光致发光性能

利用532 nm脉冲激光对沉浸在去离子水及十二烷基硫酸钠(SDS)水溶液中的金属锌靶进行液相激光烧蚀,合成了ZnO纳米颗粒和Zn/ZnO核壳结构的纳米粒子. 应用X射线衍射仪,透射电子显微镜,紫外可见光分光光度计和荧光光度计表征产物的微观结构和光学性能,并探讨其形成机理. 结果表明:在去离子水中分别烧蚀2 h和4 h生成的ZnO纳米粒子的平均粒径分别为43 nm和19 nm. 激光的长时间作用可以使纳米粒子粒径减小. 在0.005 mol/L的SDS水溶液中合成了Zn/ZnO核壳结构的纳米粒子,这是由于S 关键词： 脉冲激光烧蚀 ZnO纳米粒子 核壳结构 光致发光     

Tuning Carbon Content and Morphology of FeCo/Graphitic Carbon Core–Shell Nanoparticles using a Salt‐Matrix‐Assisted CVD Process

Large‐scale and tunable synthesis of FeCo/graphitic carbon (FeCo/GC) core–shell nanoparticles as a promising material for multipurpose biomedical applications is reported. The high‐quality graphitic structure of the carbon shells is demonstrated through high‐resolution transmission electron microscopy (HRTEM), X‐ray diffraction (XRD), and Raman spectroscopy. A saturation magnetization of 80.2 emu g^?1 is reached for the pure FeCo/GC core–shell nanoparticles. A decrease in the saturation magnetization of the samples is observed with an increase in their carbon content with different carbon morphologies evolved in the process. It is also shown how hybrid nanostructures, including mixtures of the FeCo/GC nanoparticles and multi‐walled carbon nanotubes (MWNTs) or carbon nanorods (CNRs), can be obtained only by manipulation of the carbon‐bearing gas flow rate.     

Morphological control of Ni/NiO core/shell nanoparticles and production of hollow NiO nanostructures

Chemical synthesis coupled with a microwave irradiation process allowed for the control of size (6–40 nm), shape, and shell thickness of Ni/NiO core/shell nanoparticles. In this unique synthetic route, the size of Ni nanoparticles (NiNPs) was strongly influenced by the nickel salt-to-stabilizer ratio and the amount of the stabilizer. Interestingly, it was observed that the shape of the nanoparticles was altered by varying the reaction time, where longer reaction times resulted in annealing effects and rupture of the stabilizer micelle leading to distinct shapes of Ni/NiO core/shell nanostructures. Product cooling rate was another important parameter identified in this study that not only affected the shape, but also the crystal structure of the core/shell nanoparticles. In addition, a simple and cost-effective method of microwave irradiation of NiNPs led to the formation of distinctly shaped hollow NiO nanoparticles. These high surface area core/shell nanoparticles with well-controlled morphologies are important and can lead to significant advancement in the design of improved fuel cells, electrochromic display devices, and catalysis systems.     

Synthesis and analysis of ZnO and CdSe nanoparticles

Zinc oxide and cadmium selenide particles in the nanometer size regime have been synthesized using chemical routes. The particles were capped using thioglycerol in case of ZnO and 2-mercaptoethanol in case of CdSe to achieve the stability and avoid the coalescence. Zinc oxide nanoparticles were doped with europium to study their optical properties. A variety of techniques like UV-Vis absorption spectroscopy, X-ray diffraction (XRD), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) were used to carry out structural and spectroscopic characterizations of the nanoparticles.     

Formation and strain distribution of Ni/NiO core/shell magnetic nanoparticles fabricated by pulsed laser deposition

Nucleation and growth lead to substantial strain in nanoparticles embedded in a host matrix.The distribution of strain field plays an important role in the physical properties of nanoparticles.Magnetic Ni/NiO core/shell nanoparticles embedded in the amorphous Al2O3 matrix were fabricated by pulsed laser deposition.The results from a high-resolution transmission electron microscope also revealed that the core/shell nanoparticles consist of a single crystal Ni core with a faced-centered cubic structure(Space ...     

Engineered inorganic core/shell nanoparticles

It has been for a long time recognized that nanoparticles are of great scientific interest as they are effectively a bridge between bulk materials and atomic structures. At first, size effects occurring in single elements have been studied. More recently, progress in chemical and physical synthesis routes permitted the preparation of more complex structures. Such structures take advantages of new adjustable parameters including stoichiometry, chemical ordering, shape and segregation opening new fields with tailored materials for biology, mechanics, optics magnetism, chemistry catalysis, solar cells and microelectronics. Among them, core/shell structures are a particular class of nanoparticles made with an inorganic core and one or several inorganic shell layer(s). In earlier work, the shell was merely used as a protective coating for the core. More recently, it has been shown that it is possible to tune the physical properties in a larger range than that of each material taken separately. The goal of the present review is to discuss the basic properties of the different types of core/shell nanoparticles including a large variety of heterostructures. We restrict ourselves on all inorganic (on inorganic/inorganic) core/shell structures. In the light of recent developments, the applications of inorganic core/shell particles are found in many fields including biology, chemistry, physics and engineering. In addition to a representative overview of the properties, general concepts based on solid state physics are considered for material selection and for identifying criteria linking the core/shell structure and its resulting properties. Chemical and physical routes for the synthesis and specific methods for the study of core/shell nanoparticle are briefly discussed.     

小粒径同质/异质壳层结构NaGdF_4:3%Nd~(3+)纳米颗粒的近红外发光特性

采用共沉淀法制备了粒径小于5 nm的六方相NaGdF_4:3%Nd~(3+)纳米颗粒.纳米颗粒表面缺陷会使发光中心产生严重的淬灭,对其表面包覆适当厚度的壳层可以有效地减少发光淬灭,提高发光性能.对NaGdF_4:3%Nd~(3+)核心纳米颗粒分别进行同质和异质包覆并且通过调节核壳比制备了不同壳层厚度的NaGdF_4:3%Nd~(3+)@NaGdF_4和NaGdF_4:3%Nd~(3+)@Na YF4纳米颗粒,研究了不同的壳层厚度对核心纳米颗粒发光的影响,并对两种不同核壳结构纳米颗粒的发光性能进行了对比.在808 nm近红外光激发下,NaGdF_4:3%Nd~(3+)纳米颗粒发射出位于约866,893,1060 nm的近红外发射.与核心纳米颗粒相比,核壳结构的纳米颗粒的荧光强度增强,荧光寿命增长,并且随着壳厚的增加,荧光强度出现先增强后减弱、荧光寿命逐步增长的趋势.与相同条件下同质包覆的NaGdF_4:3%Nd~(3+)@NaGdF_4纳米颗粒相比,异质包覆的NaGdF_4:3%Nd~(3+)@NaYF_4纳米颗粒光谱荧光强度增强,寿命增长.     

High UV-shielding Performance of Zinc Oxide/High-Density Polyethylene Nanocomposites

Zinc oxide/high-density polyethylene nanocomposites with high-UV-shielding efficiency were reported. Zinc oxide nanoparticles were synthesized by the homogeneous precipitation method and calcination of the precursor at different temperatures. Zinc oxide/high-density polyethylene nanocomposites were subsequently prepared from high-density polyethylene and as-prepared zinc oxide nanoparticles via melt mixing process. The structural properties of the as-prepared zinc oxide nanoparticles and nanocomposites were studied in detail using X-ray diffractometer, Fourier transform infrared spectrometer, thermogravimetry, differential scanning calorimeter, ultrasonic pulse echo technique, scanning electron microscopy, and transmission electron microscope. The optical properties of the obtained nanocomposites were shown to depend on zinc oxide particle size and content. The nanocomposite containing zinc oxide nanoparticles with an average particle size of 25.22 nm after calcination at 350°C was found to have the most optimal optical properties, namely high-visible light transparency and high-UV light shielding efficiency, which are desirable for many important applications.     

Electron microscopic study of thin CdS films

The results obtained by investigating the surface morphology and optical properties of thin CdS films formed on transparent glass and glass/indium-tin oxide (ITO) substrates via the chemical and electro-chemical methods are presented. Thin cadmium sulfide films are employed as optical windows in thin-film polycrystalline solar cells. Closely packed cadmium sulfide nanoparticles are observed on the conducting oxide (ITO) surface by means of atomic-force microscopy. Large particles (150–300 nm) comprise smaller particles with sizes of 20–30 nm. Thin CdS layers are characterized by a relatively high level of transmission (～60%) in the long-wavelength spectral region (520–600 nm).     

Metal Nanoparticle Coating of Oxide Nanospheres for Core‐Shell Structures

A low‐temperature route for coating oxide nanospheres with metal nanoparticles to achieve core‐shell structures is introduced. First results indicating a dense coverage of silica nanospheres of about 300 nm size with regularly arranged Ag and Au nanoparticles deposited by a modified incipient wetness impregnation procedure are presented. This synthesis works completely without external reducing agents or media, adhesive aids or functionalizing agents. Metal particles of only a few nanometers in size may serve as seeds for continuous metal coating of the oxide spheres by complementary processes. Structural characterization of the materials by transmission electron microscopy reveals a nearly spherical shape of the metal particles, the structure of which ranges from single crystalline to single twinned and multiply twinned configurations.     

Synthesis of CdSe/CdS with a simple non-TOP-based route

A convenient and non-TOP-based route for the synthesis of core-shell CdSe/CdS quantum dots (QDs) is developed for the first time. Simple reagents, such as cadmium oxide, selenium powder, sodium sulfide, paraffin and oleic acid with obvious advantages are used to replace organometallics. This simple route allows the preparation of a series of core-shell CdSe/CdS QDs emitting in a wide wavelength range (from 510 to 615 nm). After passivation of CdSe by CdS shell using sodium sulfide as the source of sulfur at 80 °C, the quantum yields (QYs) are improved from 15-30% to 35-50% and remained stable at least for 4 months. A narrow bandwidth (FWHM<50 nm) indicates that the as-prepared QDs have uniform size distribution, desirable dispersibility and good fluorescence properties. The whole procedure can be carried out either open to air or under nitrogen atmosphere, which is simpler, greener and cheaper as compared with TOP-based route.