Acute toxicity of ferric oxide and zinc oxide nanoparticles in rats

We investigated the toxic effects of inhalation exposure to ferric oxide (Fe2O3) and zinc oxide (ZnO) nanoparticles in rats. Male Wistar rats were consecutively treated with Fe22O3 at 8.5 mg/kg body weight and ZnO nanoparticles at 2.5 mg/kg body weight, twice daily for 3 days. Content of Fe2O3 and ZnO in tissues, biochemical parameters in serum, and hispathological examinations were analyzed at 12 h and 36 h after the 3 day treatment. In the Fe2O3-treated group, iron (Fe) content in liver and lung tissues was significantly increased at 36 h. In the ZnO-treated group, zinc (Zn) content in liver tissues was significantly increased at 12 h and further increased at 36 h. The levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total protein (TP), creatine kinase (CK), and lactate dehydrogenase (LDH) in both nanoparticle-exposed groups were significantly decreased compared to the unexposed controls. Histopathological examination showed that both types of nanoparticles caused severe damage in liver and lung tissues. Although this damage progressed in both liver and lung throughout the postexposure period, no significant elevation of serum enzyme activities was observed in response to either nanoparticle type.     

Synthesis of zinc and zinc oxide nanoparticles from zinc electrode using plasma in liquid

Nanoparticles are synthesized efficiently from zinc electrode by microwave plasma in liquid. The nanoparticles synthesized from alcohol resulted in pure zinc particles in the shape of spheres or hexagonal cylinders with a production rate of 3.3 g/h, and energy consumption of 267 J/mg for 1 mg. Whereas the nanoparticles synthesized in pure water are composed of Zn and ZnO. The Zn reacts with water through heat or the passage of time to become ZnO, releasing hydrogen gas. An upper disk placed 1 mm away from the electrode along with the bubbles generated simultaneously with the plasma ignition plays a key role in the synthesis of nanoparticles.     

Optical and electrical properties of aluminum-doped zinc oxide nanoparticles

Aluminum-doped zinc oxide nanopowders were prepared using a surfactant assisted complex sol–gel method, and were characterized using inductively coupled plasma, X-ray diffraction, scanning electron microscopy/energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and UV–Vis spectroscopy. Al was effectively doped into the ZnO matrix with concentrations up to 6.00 atomic ratio percents (at.%). X-ray diffraction results revealed that all of the nanoparticles had a pure hexagonal wurtzite structure free of any impurities when annealing temperature was below 1273 K. The optical band gap of the nanopowders, which was affected by the Al-doping concentration, reached a maximum of 3.43 eV when ZnO was doped with 4.00 at.% Al. The effect of post-annealing temperature and vacuum conditions on the resistivities of the Al-doped ZnO nanoparticles was also investigated. And the lowest volume resistivity (1.2 Ω cm) was achieved by annealing the Al-doped ZnO nanoparticles in a vacuum at 1173 K for 2 h.     

Formation of zinc oxide nanoparticles by mechanochemical reaction

Abstract

The synthesis of zinc oxide (ZnO) nanocrystallites by mechanochemical reaction of ZnCl₂ and Na₂CO₃ with NaCl as diluent and following thermal treatment was investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Calcination of the as milled powder at 600°C in air and removal of NaCl through washing formed ZnO nanocrystallites with an average crystal size of ~ 21 nm, which increased with increasing thermal treatment temperature. Milling time and NaCl/ZnCl₂ molar ratio exerted prominent effects on the crystal size of the ZnO nanoparticles. The mechanism of nanocrystallite growth is discussed.     

Chemical vapor synthesis of size-selected zinc oxide nanoparticles

ZnO can be regarded as one of the most important metal oxide semiconductors for future applications. Similar to silicon in microelectronics, it is not only important to obtain nanoscale building blocks of ZnO, but also extraordinary purity has to be ensured. A new gas-phase approach to obtain size-selected, nanocrystalline ZnO particles is presented. The tetrameric alkyl-alkoxy zinc compound [CH(3)ZnOCH(CH(3))(2)](4) is chemically transformed into ZnO, and the mechanism of gas-phase transformation is studied in detail. Furthermore, the morphological genesis of particles via gas-phase sintering is investigated, and for the first time a detailed model of the gas-phase sintering processes of ZnO is presented. Various analytical techniques (powder XRD, TEM/energy-dispersive X-ray spectroscopy, magic-angle spinning NMR spectroscopy, FTIR spectroscopy, etc.) are used to investigate the structure and purity of the samples. In particular, the defect structure of the ZnO was studied by photoluminescence spectroscopy.     

Synthesis and anti-ultraviolet properties of monodisperse BSA-conjugated zinc oxide nanoparticles

A three-step process was designed to fabricate bovine serum albumin (BSA)-conjugated zinc oxide nanoparticles (BZnOs) by using BSA as the structure directing agent. The morphology and crystal phase of BZnOs were characterized by transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). The composition and BSA content of BZnOs were measured by Fourier transform infrared spectrograph (FTIR) and thermogravimetry (TG) analysis. The ultraviolet-visible absorption property and ultraviolet blocking effects of BZnOs were also studied. The results indicated that the monodisperse BZnOs with 20.5 ± 3.5 nm in diameter had better anti-ultraviolet activities and exhibited the potential as the sunscreen.     

Controllable preparation and sterilization activity of zinc aluminium oxide nanoparticles

The zinc aluminium oxide (ZAO) NPs with homogeneous dispersion and crystal stability were prepared through synergistic reaction with ultrasonic-microwave and different dispersants. The products were characterized by X-ray diffraction analysis, transmission electron microscopy and UV–vis absorption spectra. The ZAO NPs of 45, 30, 25 and 20 nm in diameter could be controllably obtained under the same reaction conditions. These ZAO NPs were high crystalline and with wurtzite crystal structure. Specially, the sterilization activity of ZAO NPs was investigated firstly. Our bacteriological study showed the enhanced sterilization activity of ZAO NPs compared with ZnO NPs. This demonstrated that the bactericidal efficacy of ZAO NPs increases with decreasing particle size.     

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.     

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。     

Functional finishing in cotton fabrics using zinc oxide nanoparticles

Nanotechnology, according to the National Nanotechnology Initiative (NNI), is defined as utilization of structure with at least one dimension of nanometer size for the construction of materials, devices or systems with novel or significantly improved properties due to their nano-size. The nanostructures are capable of enhancing the physical properties of conventional textiles, in areas such as anti-microbial properties, water repellence, soil-resistance, anti-static, anti-infrared and flame-retardant properties, dyeability, colour fastness and strength of textile materials. In the present work, zinc oxide nanoparticles were prepared by wet chemical method using zinc nitrate and sodium hydroxide as precursors and soluble starch as stabilizing agent. These nanoparticles, which have an average size of 40 nm, were coated on the bleached cotton fabrics (plain weave, 30 s count) using acrylic binder and functional properties of coated fabrics were studied. On an average of 75%, UV blocking was recorded for the cotton fabrics treated with 2% ZnO nanoparticles. Air permeability of the nano-ZnO coated fabrics was significantly higher than the control, hence the increased breathability. In case of nano-ZnO coated fabric, due to its nano-size and uniform distribution, friction was significantly lower than the bulk-ZnO coated fabric as studied by Instron® Automated Materials Testing System. Further studies are under way to evaluate wash fastness, antimicrobial properties, abrasion properties and fabric handle properties.     

Electrical and gas sensing properties of self-aligned copper-doped zinc oxide nanoparticles

Electrical and gas sensing properties of nanocrystalline ZnO:Cu, having Cu X wt% (X = 0.0, 0.5, 1.0, and 1.5) in ZnO, in the form of pellet were investigated. Copper chloride and zinc acetate were used as precursors along with oxalic acid as a precipitating reagent in methanol. Material characterization was done by X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM) and inductive coupled plasma with optical emission spectrometry (ICP-OES). FE-SEM showed the self-aligned Cu-doped ZnO nano-clusters with particles in the range of 40-45 nm. The doping of 0.5% of copper changes the electrical conductivity by an order of magnitude whereas the temperature coefficient of resistance (TCR) reduces with increase in copper wt% in ZnO. The material has shown an excellent sensitivity for the H₂, LPG and CO gases with limited temperature selectivity through the optimized operating temperature of 130, 190 and 220 °C for H₂, LPG and CO gases, respectively at 625 ppm gas concentration. The %SF was observed to be 1460 for H₂ at 1% Cu doping whereas the 0.5% Cu doping offered %SF of 950 and 520 for CO and LPG, respectively. The response and recovery time was found to be 6 to 8 s and 16 s, respectively.     

Formation of zinc oxide nanoparticles during electric discharge in water

A method for obtaining nanodimensional structures of zinc oxide (ZnO) by means of electric discharge in water is described. Data on the phase composition and luminescent properties of the synthesized ZnO powder deposited from a colloidal solution onto single crystal silicon surface are presented. It is shown that the partial concentrations of zinc in the oxide and metallic phases in the colloidal solution depend on the supply of oxygen to the zone of the chemical reaction. Optimum conditions for the discharge synthesis of nanodimensional powder with an almost 100% ZnO content have been found.     

From zinc oxide nanoparticles to microflowers: A study of growth kinetics and biocidal activity

Zinc oxide (ZnO) particles with varying morphologies from spherical particles to flower-like structure were synthesized by a simple wet-chemical method involving reaction between metal acetate and a long chain amine by an addition–elimination process. The influence of amine as a precursor and morphology directing agent is illustrated and the possible mechanism is discussed. Structural and optical studies reveal the formation of hexagonal wurtzite structure of ZnO with sufficient defects in the form of oxygen vacancies and the concentration of defects has been found to be dependent on the shape of zinc oxide nanostructures (ZnO-NSs). As example for promising applications, the antibacterial activities of the as prepared ZnO-NSs were preliminarily studied against gram positive (Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus agalactiae and Bacillus subtilis) and gram negative (Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium) bacteria and are found to be dependent on the shape of the nanostructures. Survival percentage of each of these pathogens in the presence of the nanostructures has been evaluated. Antibacterial efficacies of the nanostructures were calculated and it has been observed that spherical nanoparticles are most toxic among the nanostructures tested. The major contribution for this biocidal activity has been proposed to arise from the release of reactive ion species (ROS) from the surface of ZnO when in solution.     

Study of the properties of undoped and fluorine doped zinc oxide nanoparticles

ZnO and ZnO:F nanoparticles were successfully prepared by precipitation in the presence of oxalic acid. This procedure yields ZnO and ZnO:F nano-arrangements of different lengths consisting of chains of quasi-spherical nanoparticles of ∼ 30 nm in size. Only the wurtzite ZnO structure was detected for both undoped and fluorine doped ZnO nanoparticles. By absorption and photoluminescence measurements, a diminishing of singly ionized oxygen vacancies was detected when fluorine is present in the nanoparticles; while a blue shift of the exciton absorption was observed. Additionally, by NIR reflectance measurements, the creation of free carriers by the fluorine doping of ZnO nanoparticles was observed.     

Preparation of self-assembled zinc oxide nanoparticles multilayer films under ultrasonic irradiation

Zinc oxide nanoparticles were synthesized and self-assembled on the reactive surface of a glass slide functionalized with (3-mercaptopropyl)-trimethoxysilane under ultrasonic irradiation. The structure, morphology, and optical property of the zinc oxide nanoparticles were investigated by TEM, XRD, and UV-vis spectroscopy. The functionalized glass slide was soaked in an aqueous solution which dispersed zinc oxide nanoparticles under ultrasonic irradiation. Zinc oxide multilayer films grew up to several layers (up to 5 layers) depending on the immersion time. The self-assembled zinc oxide nanoparticles multilayer films were characterized using UV-vis spectroscopy and SEM. Ultrasonic irradiation was an efficient method to make multilayer films on the functionalized glass slide with zinc oxide nanoparticles.     

Photocatalytic degradation of selected pharmaceuticals using green fabricated zinc oxide nanoparticles

Heterogeneous photocatalysis is one of the popular alternative treatment methods for wastewater. It utilizes semiconductor material as the catalyst and metal oxide such as zinc oxide nanoparticles (ZnO NPs), emerged as the commonly used catalyst. In this study, a series of biogenic ZnO NPs was fabricated through precipitation method with pullulan as the biomaterial. The amount of zinc salt in the presence of pullulan was varied to study its impact on the generated ZnO NPs. The results showed that without pullulan, the average particle size of ZnO NPs obtained was 110.86 nm. With 0.84 M zinc salt in 50 g/L of pullulan, the ZnO NPs average particle size significantly reduced to 58.13 nm. The surface area of all synthesized ZnO NPs ranging from 14.84 to 19.99 m² g^?1. The photocatalytic activities of all synthesized ZnO NPs were evaluated through the photodegradation of two drugs, amoxicillin (AMX) and paracetamol (PCT). Through the comparison of drugs’ photodegradation with all synthesized ZnO NPs, ZnO NPs produced with 0.67 M zinc salt in 50 g/L of pullulan showed the highest degradation percentage of 85.7% and 96.8% for AMX and PCT respectively. The best photodegradation conditions for the drugs were 30 ppm drugs concentration, pH 9 (for AMX) and pH 5 (for PCT) and 50 mg catalyst dosage. Based on these results, biogenic ZnO NPs has high potential to be used in the treatment of pharmaceutical wastewater.     

Synthesis,characterisation and antimicrobial activity of manganese- and iron-doped zinc oxide nanoparticles

The present work reports study on antimicrobial activity of pure and doped ZnO nanocomposites. Polyvinyl pyrrolidone capped Mn- and Fe-doped ZnO nanocomposites were synthesised using simple chemical co-precipitation technique. The synthesised materials were characterised using transmission electron microscope (TEM), X-ray powder diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), Fourier transform infrared (FTIR) spectroscopy and ultraviolet (UV) visible spectroscopy. The XRD and TEM studies reveal that the synthesised ZnO nanocrystals have a hexagonal wurtzite structure with average crystalline size ～7–14 nm. EDXRF and FTIR study confirmed the doping and the incorporation of impurity in ZnO nanostructure. The antimicrobial activities of nanoparticles (NPs) were studied against fungi, gram-positive and gram-negative bacteria using the standard disc diffusion method. The photocatalytic activities of prepared NPs were evaluated by degradation of methylene blue dye in aqueous solution under UV light irradiation. Experimental results demonstrated that ZnO NPs doped with 10% of Mn and Fe ions showed maximum antimicrobial and photodegradation efficiency in contrast with that of the 1% loading. The enhancement in antimicrobial effect and photocatalytic degradation is attributed to the generation of reactive oxygen species due to the synergistic effects of Mn and Fe loading.     

Hazardous phytotoxic nature of cobalt and zinc oxide nanoparticles assessed using Allium cepa

The increasing use of nanotechnology requires the clarification of the behavior and the effects of nanoparticles (NPs) as they are released into the environment. This study was to investigate the phytotoxicity of cobalt and zinc oxide NPs using the roots of Allium cepa (onion bulbs) as an indicator organism. The effects of cobalt and zinc oxide NPs on the root elongation, root morphology, and cell morphology of a plant, as well as their adsorption potential, were determined through the hydroponic culturing of A. cepa. A. cepa roots were treated with dispersions of the cobalt and zinc oxide NPs having three different concentrations (5, 10, and 20 μg ml(-1)). With increasing concentrations of the NPs, the elongation of the roots was severely inhibited by both the cobalt and the zinc oxide NPs as compared to that in the control plant (untreated A. cepa roots). Massive adsorption of cobalt oxide NPs into the root system was responsible for the phytotoxicity. Zinc oxide NPs caused damage because of their severe accumulation in both the cellular and the chromosomal modules, thus signifying their highly hazardous phytotoxic nature.     

Improved gypsum plaster by incorporation of zinc oxide nanoparticles (ZnO-NPs)

Journal of Materials Science - Gypsum plaster is used in linings, coatings, decorative elements, and sealing and is a component of drywall. However, it is susceptible to the development of mold and...