纳米ZnO的制备

本文研究了以Zn (No3 ) 2 、尿素为原料 ,加入表面活性剂改性制备纳米氧化锌粉体的方法。实验讨论了Zn (NO3 ) 2 浓度、尿素浓度、pH值、焙烧温度对纳米氧化锌粒径的影响。用扫瞄电镜和粒度分析仪确定纳米氧化锌的形貌和粒径     

Green synthesised zinc oxide nanostructures through Periploca aphylla extract shows tremendous antibacterial potential against multidrug resistant pathogens

To grapple with multidrug resistant bacterial infections, implementations of antibacterial nanomedicines have gained prime attention of the researchers across the globe. Nowadays, zinc oxide (ZnO) at nano‐scale has emerged as a promising antibacterial therapeutic agent. Keeping this in view, ZnO nanostructures (ZnO‐NS) have been synthesised through reduction by P. aphylla aqueous extract without the utilisation of any acid or base. Structural examinations via scanning electron microscopy (SEM) and X‐ray diffraction have revealed pure phase morphology with highly homogenised average particle size of 18 nm. SEM findings were further supplemented by transmission electron microscopy examinations. The characteristic Zn–O peak has been observed around 363 nm using ultra‐violet–visible spectroscopy. Fourier‐transform infrared spectroscopy examination has also confirmed the formation of ZnO‐NS through detection of Zn–O bond vibration frequencies. To check the superior antibacterial activity of ZnO‐NS, the authors'' team has performed disc diffusion assay and colony forming unit testing against multidrug resistant E. coli, S. marcescens and E. cloacae. Furthermore, protein kinase inhibition assay and cytotoxicity examinations have revealed that green fabricated ZnO‐NS are non‐hazardous, economical, environmental friendly and possess tremendous potential to treat lethal infections caused by multidrug resistant pathogens.Inspec keywords: nanomedicine, zinc compounds, II‐VI semiconductors, wide band gap semiconductors, nanoparticles, scanning electron microscopy, X‐ray diffraction, antibacterial activity, transmission electron microscopy, particle size, Fourier transform infrared spectra, ultraviolet spectra, visible spectra, enzymes, biochemistry, molecular biophysics, microorganisms, drugs, toxicology, bonds (chemical), semiconductor growth, nanofabrication, vibrational modesOther keywords: green synthesised zinc oxide nanostructures, Periploca aphylla extract, antibacterial potential, multidrug resistant pathogens, multidrug resistant bacterial infections, antibacterial nanomedicines, P. aphylla aqueous extract, structural examinations, scanning electron microscopy, X‐ray diffraction, pure phase morphology, homogenised average particle size, SEM, transmission electron microscopy, Fourier‐transform infrared spectroscopy, bond vibration frequency, antibacterial activity, disc diffusion assay, colony forming unit testing, S. marcescens, E. cloacae, E. coli, ultraviolet‐visible spectroscopy, protein kinase inhibition assay, cytotoxicity, lethal infections, ZnO     

Electronic properties of polyvinylpyrrolidone at the zinc oxide nanoparticle surface

We investigated the electrical effects of polyvinylpyrrolidone (PVP), used as a dispersion agent in zinc oxide (ZnO) nanodispersions. We found PVP reduces the high surface conductivity and atmospheric sensitivity. Compared with polymer free ZnO thin films, the nanoparticulate layers with PVP exhibit a smaller density of thermally active charge carriers, a reduced density of trap states, and a Fermi level shift toward the valence band, yielding improved performance, vanishing hysteresis characteristics and reduced atmospheric sensitivity in thin film transistors (TFT). In addition, we discuss the attachment of PVP to the ZnO surface.     

Enhanced ultraviolet sensitivity of zinc oxide nanoparticle photoconductors by surface passivation

Zinc oxide nanoparticles were created by a top-down wet-chemical etching process and then coated with polyvinyl-alcohol (PVA), exhibiting sizes ranging from 10 to 120 nm with an average size approximately 80 nm. The PVA layer provides surface passivation of zinc oxide nanoparticles. As a result of PVA coating, enhancement in ultraviolet emission and suppression of parasitic green emission is observed. Photoconductors fabricated using the PVA coated zinc oxide nanoparticles exhibited a ratio of ultraviolet photo-generated current to dark current as high as 4.5 × 10⁴, 5 times better than that of the devices fabricated using uncoated ZnO nanoparticles.     

Hollow iron oxide nanoparticles as multidrug resistant drug delivery and imaging vehicles

Magnetic nanoparticles have been used as drug delivery vehicles against a number of cancer cells. Most of these theranostic formulations have used solid iron oxide nanoparticles (SIONPs) loaded with chemotherapeutics as nano-carrier formulation for both magnetic resonance imaging (MRI) and cancer therapy. In this study, we applied the dopamine-plus-human serum albumin (HSA) method to modify hollow iron oxide nanoparticles (HIONPs) and encapsuated doxorubicin (DOX) within the hollow porous structure of the nano-carrier. The new delivery system can load more drug than solid iron oxide nanoparticles of the same core size using the same coating strategy. The HIONPs-DOX formulation also has a pH-dependent drug release behaviour. Compared with free DOX, the HIONPs-DOX were more effectively uptaken by the multidrug resistant OVCAR8-ADR cells and consequently more potent in killing drug resistant cancer cells. MRI phantom and cell studies also showed that the HIONPs-DOX can decrease the T ₂ MRI signal intensity and can be used as a MRI contrast agent while acting as a drug delivery vehicle. For the first time, the dual application of chemo drug transport and MR imaging using the HIONPs-DOX formulation was achieved against both DOX-sensitive and DOX-resistant cancer cells.      

Preparation of surface modified zinc oxide nanoparticle with high capacity dye removal ability

In this paper, the surface modification of zinc oxide nanoparticle (ZON) by amine functionalization was studied to prepare high capacity adsorbent. Dye removal ability of amine-functionalized zinc oxide nanoparticle (AFZON) and zinc oxide nanoparticle (ZON) was also investigated. The physical characteristics of AFZON were studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Acid Blue 25 (AB25), Direct Red 23 (DR23) and Direct Red 31 (DR31) were used as model compounds. The effect of operational parameters such as dye concentration, adsorbent dosage, pH and salt on dye removal was evaluated. The isotherm and kinetic of dye adsorption were studied. The maximum dye adsorption capacity (Q₀) was 20 mg/g AB25, 12 mg/g DR23 and 15 mg/g DR31 for ZON and 1250 mg/g AB25, 1000 mg/g DR23 and 1429 mg/g DR31 for AFZON. It was found that dye adsorption followed Langmuir isotherm. Adsorption kinetic of dyes was found to conform to pseudo-second order kinetics. Dye desorption tests (adsorbent regeneration) showed that the maximum dye release of 90% AB25, 86% for DR23 and 90% for DR31 were achieved in aqueous solution at pH 12. Based on the data of the present investigation, it can be concluded that the AFZON being an adsorbent with high dye adsorption capacity might be a suitable alternative to remove dyes from colored aqueous solutions.     

Silver-modified iron oxide nanoparticle impregnated fiberglass for disinfection of bacteria and viruses in water

Recent work has shown that a new material system composed of iron oxide (Fe₂O₃) nanoparticles loaded onto a fiberglass support displays excellent antiviral properties against the model virus, MS2 phage, but is ineffective against bacteria, specifically Escherichia coli (E. coli). To increase the antibacterial properties and still maintain antiviral activity, silver (Ag) nanoparticles were added to this system through an aqueous hydrothermal reduction process with 0.25 M silver nitrate (AgNO₃). A 0.05 mg/mL loading of the new Ag modified oligodynamic nanoparticle impregnated fiberglass system consisting of Fe₂O₃ (9.1 wt.%) and Ag (0.1 wt.%)/g-fiber, displayed robust antibacterial activity by achieving a 2 log removal of 10⁶ CFU/mL E. coli in 1 min. The inactivation rate of the Ag-modified Fe₂O₃ impregnated fiberglass (FG-Fe₂O₃/Ag) system was comparable to previously reported Ag nanoparticle impregnated fiberglass. The FG-Fe₂O₃/Ag displayed excellent dynamic performance, effectively eliminating 10⁶E. coli CFU/mL with no bacterial breakthrough up to 250 bed volumes.     

Honokiol–camptothecin loaded graphene oxide nanoparticle towards combinatorial anti‐cancer drug delivery

Honokiol (HK) is a natural product isolated from the bark, cones, seeds and leaves of plants belonging to the genus Magnolia. It possesses anti‐cancer activity which can efficiently impede the growth and bring about apoptosis of a diversity of cancer cells. The major concerns of using HK are its poor solubility and lack of targeted drug delivery. In this study, a combinatorial drug is prepared by combining HK and camptothecin (CPT). Both CPT and HK belong to the Magnolian genus and induce apoptosis by cell cycle arrest at the S‐phase and G1 phase, respectively. The combinatorial drug thus synthesised was loaded onto a chitosan functionalised graphene oxide nanoparticles, predecorated with folic acid for site‐specific drug delivery. The CPT drug‐loaded nanocarrier was characterised by X‐ray diffractometer, scanning electron microscope, transmission electron microscope, UV–vis spectroscopy and fluorescence spectroscopy, atomic force microscopy. The antioxidant properties, haemolytic activity and anti‐inflammatory activities were analysed. The cellular toxicity was analysed by 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐Diphenyltetrazolium Bromide (MTT assay) and Sulforhodamine B (SRB) assay against breast cancer (MCF‐7) cell lines.Inspec keywords: nanofabrication, cancer, nanoparticles, atomic force microscopy, graphene, scanning electron microscopy, cellular biophysics, toxicology, transmission electron microscopy, drug delivery systems, nanomedicine, tumours, solubilityOther keywords: targeted drug delivery, combinatorial drug, Magnolian genus, apoptosis, cell cycle, chitosan functionalised graphene oxide nanoparticles, site‐specific drug delivery, CPT drug‐loaded nanocarrier, transmission electron microscope, fluorescence spectroscopy, haemolytic activity, antiinflammatory activities, breast cancer cell lines, honokiol–camptothecin loaded graphene oxide nanoparticle, combinatorial anti‐cancer drug delivery, natural product, genus Magnolia, anticancer activity, cancer cells     

A study on electrodeposited zinc oxide nanostructures

Zinc oxide (ZnO) nanostructures prepared by electrochemical deposition method from aqueous zinc nitrate solution at 65 °C onto fluorine doped tin oxide coated glass substrates were investigated. Characterization of ZnO nanostructures was realized using conventional electrochemical techniques, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Cyclic voltammetry experiments were performed to elucidate the electrodic processes that occurred when potentials were applied and the optimum potential for electrodeposition were determined. From the Mott-Schottky measurements, the flat-band potential and the donor density for the ZnO nanostructure are determined. From single-step potential experiment in the potential ranges from ?1.1 to ?1.4 V, the formation of ZnO nuclei in the early deposition stages was proceeded according to the three dimensional (3D) instantaneous nucleation followed by diffusion-limited growth rather than a progressive one. SEM images demonstrated that the morphology of ZnO nanostructures depend greatly on the potential depositions. XRD studies revealed that the deposited films were polycrystalline in nature with wurtzite phase.     

纳米ZnO材料的一种简单制备方法

采用简单的水浴加热法,在较低的温度下(90℃),以氯化锌(ZnCl2)溶液和氢氧化钠(NaOH)溶液为原料,仅通过简单的磁力搅拌制得了直径在80～120nm间的纳米ZnO花状产物,并应用SEM、XRD、TEM和PL分析手段,对样品的形貌结构和光致发光性能进行了表征,并对其生长机理进行了讨论。     

Photo‐induced Leishmania DNA degradation by silver‐doped zinc oxide nanoparticle: an in‐vitro approach

Recently, the authors reported newly synthesised polyethylene glycol (PEG)ylated silver (9%)‐doped zinc oxide nanoparticle (doped semiconductor nanoparticle (DSN)) which has high potency for killing Leishmania tropica by producing reactive oxygen species on exposure to sunlight. The current report is focused on Leishmania DNA interaction and damage caused by the DSN. Here, we showed that the damage to Leishmania DNA was indirect, as the DSN was unable to interact with the DNA in intact Leishmania cell, indicating the incapability of PEGylated DSN to cross the nucleus barrier. The DNA damage was the result of high production of singlet oxygen on exposure to sunlight. The DNA damage was successfully prevented by singlet oxygen scavenger (sodium azide) confirming involvement of the highly energetic singlet oxygen in the DNA degradation process.Inspec keywords: silver, zinc compounds, nanoparticles, nanomedicine, DNA, microorganisms, cellular biophysics, biomedical engineeringOther keywords: photo‐induced Leishmania DNA degradation, PEGylated silver‐doped zinc oxide nanoparticle, Leishmania tropica, reactive oxygen species, sunlight, Leishmania DNA interaction, Leishmania cell, DNA damage, singlet oxygen scavenger, sodium azide, DNA degradation process, ZnO:Ag     

Carrier transport in polycrystalline transparent conductive oxides: A comparative study of zinc oxide and indium oxide

Highly doped indium-tin oxide films exhibit resistivities ρ as low as  1.2 × 10^− 4 Ω cm, while for ZnO films resistivities in the range of 2 to 4 × 10^− 4 Ω cm are reported. This difference is unexpected, if ionized impurity scattering would be dominant for carrier concentrations above 10²⁰ cm^− 3. By comparing the dependences of the effective Hall mobility on the carrier concentration of ZnO and ITO it is found that grain barriers limit the carrier mobility in ZnO for carrier concentrations as high as 2 × 10²⁰ cm^− 3, independently, if the films were grown on amorphous or single crystalline substrates. Depending on the deposition method, grain barrier trap densities between 10¹² and 3 × 10¹³ cm^− 2 were estimated for ZnO layers. Also, crystallographic defects seem to reduce the mobility for highly doped ZnO films. On the other hand, for ITO films such an influence of the grain barriers was not observed down to carrier concentrations of about 10¹⁸ cm^− 3. Thus the grain barrier trap densities of ZnO and ITO are significantly different, which seems to be connected with the defect chemistry of the two oxides and especially with the piezoelectricity of zinc oxide.     

一种制备ZnO纳米颗粒的新方法

提出了一种制备ZnO纳米颗粒的新方法。在金属钠的液氨溶液中还原硝酸锌,所形成的金属Zn自然氧化而制得ZnO颗粒。为了研究表面修饰对产物形貌、粒径和性能的影响,制备了十二烷基磺酸钠（SDS）修饰的ZnO纳米颗粒。采用X射线粉末衍射仪（XRD）、透射电子显微镜（TEM）、傅立叶变换红外光谱仪（FT-IR）、热重及差热分析仪（TG-DTA）等手段对产物进行了表征。结果表明采用该方法可制得具有六方纤锌矿结构的ZnO颗粒,未修饰ZnO颗粒团聚较为严重;修饰的ZnO纳米颗粒呈棒状,分散较好。红外和热分析表明SDS修饰在了ZnO纳米颗粒表面。测试了所制备ZnO颗粒的紫外可见吸收（UV-Vis）和光致发光（PL）谱,均出现了ZnO的特征谱带。提出的方法也适用于制备其它金属或氧化物纳米材料。     

Self-assembled iron oxide nanoparticle multilayer: x-ray and polarized neutron reflectivity

We have investigated the structure and magnetism of self-assembled, 20 nm diameter iron oxide nanoparticles covered by an oleic acid shell for scrutinizing their structural and magnetic correlations. The nanoparticles were spin-coated on an Si substrate as a single monolayer and as a stack of 5 ML forming a multilayer. X-ray scattering (reflectivity and grazing incidence small-angle scattering) confirms high in-plane hexagonal correlation and a good layering property of the nanoparticles. Using polarized neutron reflectivity we have also determined the long range magnetic correlations parallel and perpendicular to the layers in addition to the structural ones. In a field of 5 kOe we determine a magnetization value of about 80% of the saturation value. At remanence the global magnetization is close to zero. However, polarized neutron reflectivity reveals the existence of regions in which magnetic moments of nanoparticles are well aligned, while losing order over longer distances. These findings confirm that in the nanoparticle assembly the magnetic dipole-dipole interaction is rather strong, dominating the collective magnetic properties at room temperature.     

A silicon nanoparticle/reduced graphene oxide composite anode with excellent nanoparticle dispersion to improve lithium ion battery performance

Composite anodes of Si nanoparticles (SiNPs) and reduced graphene oxide (RGO) sheets with highly dispersed SiNPs were synthesized to investigate the performance-related improvements that particle dispersion can impart. Three composites with varying degrees of particle dispersions were prepared using different ultrasonication, and a combination of ultrasonication and surfactant. With more dispersed SiNPs, the capacity retention and rate performance as evaluated by galvanostatic cycling using increasing current density rates (500–2500 mA/g) also improved compared with anodes that have poor particle dispersion. These results demonstrate that better nanoparticle dispersion (small clusters to mono-dispersed particles) between the stable and the highly conducting RGO layers, allows the carbonaceous matrix material to complement the SiNP-Li⁺ electrochemistry by becoming highly involved in the charge–discharge reaction mechanisms as indicated by chronopotentiometry and cyclic voltammetry (CV). Particle dispersion improvement was confirmed to be a key component in a composite anode design to maximize Si for high-performance lithium ion battery (LIB) application.     

Cytotoxicity of zinc oxide nanoparticles: importance of microenvironment

While ZnO particles are widely used in many fields, including personal care products, the high toxicity of ZnO nanoparticles has been reported and aroused great health concerns. In this study, the cytotoxicity of ZnO nanoparticles was evaluated and, in particular, the role of microenvironment in their toxicity was investigated. Our results show that ZnO nanoparticles are highly toxic to NIH/3T3 cells, inducing viability loss, membrane leakage and morphology changes. The microenviroment, here the CO2 atmosphere under cell culture condition, promoted the solubilization of ZnO nanoparticles. Then the released Zn from ZnO nanoparticles induces the cytotoxicity. The importance of microenvironment on the ZnO nanotoxicity is presented and the implications to future nanotoxicology studies are discussed.     

A high-resolution transmission electron microscope study of a zinc oxide varistor

Investigations were made of varistor microstructure, the morphology of Bi₂O₃ at multiple ZnO grain junctions, Bi₂O₃/ZnO grain boundaries and ZnO/ZnO grain boundaries (especially whether Bi₂O₃ is present or not at the ZnO/ZnO grain boundary) by means of high-resolution transmission electron microscopy and X-ray microanalysis in the scanning transmission electron microscope. Bi₂O₃ at multiple ZnO grain junctions consists of small particles of 0.1m in diameter, and they are vitrified to some extent. It is suggested that bismuth ions dissolve into ZnO grains over a 30 nm range from a Bi₂O₃/ZnO grain boundary; however, there is no bismuth at ZnO/ZnO grain boundaries.     

Zinc oxide nanostructures: epitaxially growing from hexagonal zinc nanostructures

The epitaxial growth of ZnO nanosheets and nanoneedles from a Zn/ZnO core/shell structure is verified by an experiment in which the ZnO nanoneedles and nanosheets are synthesized in air within an ultra-low temperature range from?250 to 400?°C by thermal oxidation of Zn films made up of hexagonal nanodiscs or nanoprisms. The hexagonal Zn structures are oxidized to form a Zn/ZnO core/shell structure with an epitaxial relationship; ZnO nanoneedles and nanosheets are found to grow epitaxially from the ZnO shell, along sixfold symmetric [Formula: see text] directions, showing the same lattice orientation as the Zn core. The stability difference among different facets of hexagonal Zn crystal structures plays a key role in the formation of ZnO nanosheets, nanoneedles and the Zn/ZnO core/shell structure, as well as ZnO hollow structures. A vapor-solid mechanism is suggested to explain the epitaxial growth process of the ZnO products. Photoluminescence properties of the ZnO nanostructures are also explored.