Monodispersed Zinc Oxide Research Articles

Monodispersed zinc oxide nanoparticles as multifunctional additives for polycarbonate thermoplastic with high transparency and excellent comprehensive performance

Monodispersed zinc oxide nanoparticles as multifunctional additives for polycarbonate thermoplastic with high transparency and excellent comprehensive performance

Rhodamine B Doped ZnO Monodisperse Microcapsules: Droplet-Based Synthesis, Dynamics and Self-Organization of ZnO Nanoparticles and Dye Molecules.

In the present work, droplet-based microfluidics and sol-gel techniques were combined to synthesize highly monodisperse zinc oxide (ZnO) microspheres, which can be doped easily and precisely with dyes, such as rhodamine B (RhB), and whose size can be finely tuned in the 10–30 μm range. The as-synthesized microparticles were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal microscopy. The results reveal that the microspheres exhibit an excellent size monodispersity, hollow feature, and a porous shell with a thickness of about 0.6 μm, in good agreement with our calculations. We show in particular by means of fluorescence recovery after photobleaching (FRAP) analysis that the electric charges carried by ZnO nanoparticles primary units play a crucial role not just in the formation and structure of the synthesized ZnO microcapsules, but also in the confinement of dye molecules inside the microcapsules despite a demonstrated porosity of their shell in regards to the solvent (oil). Our results enable also the measurement of the diffusion coefficient of RhB molecules inside the microcapsules ( cm/s), which is found two order of magnitude smaller than the literature value. We attribute such feature to a strong interaction between dye molecules and the electrical charges carried by ZnO nanoparticles. These results are important for potential applications in micro-thermometry (as shown recently in our previous study), photovoltaics, or photonics such as whispering gallery mode resonances.

Synthesis of zinc oxide nanoparticles and its conjugation with antibiotic: Antibacterial and morphological characterization

In the present study zinc oxide nanoparticles were synthesized through chemical method in alkaline condition. The initial formation of monodispersed zinc oxide nanoparticles was confirmed by a sharp peak at 390 nm via UV–vis spectroscopy. Further, microscopic techniques such as SEM and TEM established the formation of multi shaped zinc oxide nanoparticles with an average size of 20−24 nm. The FTIR, analysis confirmed the presence of multiple functional groups on zinc oxide nanoparticles. In addition to this, zinc oxide nanoparticles were conjugated with ciprofloxacin (antibiotic) through chemical method. Later, antibacterial potential of zinc oxide nanoparticles, ciprofloxacin and zinc oxide nanoparticles - ciprofloxacin conjugate were compared against multiple bacterial pathogens (E. coli, Klebsiella spp., B. subtilis and Streptococcus spp.). It was observed that, conjugation of zinc oxide nanoparticles with ciprofloxacin produces synergetic effect in term of antibacterial activity. Results confirmed that, there was 2.9 fold increase in antibacterial activity of nanoparticle-ciprofloxacin conjugates against E.coli and 2.8 fold increase for Streptococcus spp. as compared to ciprofloxacin alone. The present formulation clearly indicates the potential of metallic nanoparticles in the area of healthcare.

Zinc oxide nanoparticles promoting the formation of myogenic differentiation into myotubes in mouse myoblast C2C12 cells

In the present study, we investigated the effect of monodispersed zinc oxide (ZnO) nanoparticles on the proliferation, myogenic differentiation and regulation of associated myogenic marker genes. The as-prepared ZnO nanoparticles had the hexagonal wurtzite structure with maximum absorption at 355nm and the band gap energy was found to be 3.21eV. The electron microscopy analysis showed that the ZnO nanoparticles are spherical in shape with an average size range between 10 to 15nm. The XRD analysis confirmed the hexagonal structure of ZnO nanoparticles and the Raman spectroscopic analysis showed the vibrations of the zinc lattice and oxygen vibration of ZnO nanoparticles. The effect of ZnO nanoparticles on myogenic differentiation was analyzed using C2C12 cells and the results showed the nanoparticles supported the proliferation with negotiable cytotoxic activity. Moreover, the ZnO nanoparticles were significantly enhanced the myoblasts into myotube formation through upregulating the myogenic markers such as myosin heavy chain, MyoD, MyoG genes. The further analysis demonstrated that the ZnO nanoparticles regulates the non-apoptotic effect of caspases and calpain family proteins in respond to the enhancement of myogenic differentiation. Together, the ZnO nanoparticles provide an additional evidence for the role of nanomaterials in skeletal muscle repair and tissue regeneration engineering.

Biofabrication of size-controlled ZnO nanoparticles using various capping agents and their cytotoxic and antitermite activity

ABSTRACT Herein, monodisperse Zinc oxide nanoparticles (ZnO-NPs) have been fabricated by green adeptness with and without using capping agents. The different capping agents used include Syzygium cumini leaves extract, starch and cetyl trimethyl ammonium bromide (CTAB). The UV/Vis analysis showed an exciton absorption band in the range of 370–385 nm for all NPs. The SEM analysis showed that average particle size of all ZnO NPs was consistent with that which was calculated by using the Debye-Scherrer equation also by using effective mass model approach. The XRD analysis has confirmed their crystalline nature and monodisperse size distribution. The Photoluminescence spectrum (PL) indicated the presence of surface defects on ZnO nanoparticles, which are the` driving force in the efficient photocatalysis of brilliant green dye showing 89.33% degradation efficiency after 2 h. The plant-mediated ZnO NPs were an efficient antimicrobial agent against P. aeruginosa, E. coli, A.baumannii and K. pneumoniae strains; however, all fungal strains including P. chrysogenum, A. niger, T. citrinoviride, A. fumigatus were resistant to ZnO NPs at all concentrations. Furthermore, they showed a strong antitermite activity against Heterotermes indicola workers and soldiers with a 100% mortality rate in 24 h.

Room Temperature Synthesis of Monodisperse ZnO Nanoparticles Using Ultrasonically Atomized Precursor Mist in Simple Chemical Route

Monodisperse zinc oxide (ZnO) nanoparticles were synthesized using ultrasonically atomized precursor mist in simple chemical route at low temperature. Analytical grade sodium hydroxide and zinc chloride were dissolved in 100 ml methanol. Zinc chloride precursor solution was converted into very fine mist (atomized) using a nozzle (Sono-Tek Corporation, U.S.A.) operated at ultrasonic frequency of 120 KHz. Fine mist droplets were added slowly (50ml/ hour) into sodium hydroxide solution in 2 hours. The NaOH solution in beaker turned slowly into white product due to addition of zinc chloride. The white product was kept in constant temperature bath at 90°C for 3 hours. The white product was washed five times using double distill water and dried in oven for 2 hours. Different powder samples were synthesized using same procedure by changing the molarity of sodium hydroxide keeping the molarity of zinc chloride and other preparative conditions same. The structural, microstructural, thermal and optical properties of fine powders were analyzed using X Ray Diffractometer, Scanning Electron Microscopy, Simultaneous Thermal Analyzer, UV-Vis Spectroscopy and Photoluminescence Spectroscopy. Fine ZnO nanorods, elongated and spherical nanoparticles were observed due to change in molarity of NaOH. The results are discussed and interpreted.

Fluorescent ZnO quantum dots synthesized with urea for the selective detection of Cr6+ ion in water with a wide range of concentrations

Nearly monodisperse Zinc oxide (ZnO) quantum dots (QDs) displayed yellow fluorescence were synthesized using urea as dispersant. In this paper, urea-ZnO QDs were used as fluorescent probe to detect Cr6+ in solution. The emission from the as-synthesized urea-ZnO QDs is selectively quenched when Cr6+ ions were added. Moreover, there are two linear relationships between the quenching of fluorescence intensity and the Cr6+ concentrations ranging from 4 μM to 1000 μM, with the detection limit for Cr6+ at 19.53 nM (on basis of 3σ/slope criterion). The quenching of fluorescence is attributed to aggregation of the QDs and charge transfer between the QDs and Cr6+ by measurements of transmission electron microscopy (TEM) images, UV–visible absorption spectra and fluorescence lifetime.

Evaluation of antibacterial and antioxidant potential of the zinc oxide nanoparticles synthesized by aqueous and polyol method

In this paper, we have reported the synthesis, characterization, and evaluation of antimicrobial and antioxidant potential of monodispersed Zinc Oxide (ZnO) nanoparticles synthesized by the room temperature precipitation (aqueous phase) and polyol method (organic phase). ZnO nanoparticle synthesized by both the methods had shown excellent DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging, metal chelating (MC), ABTS (2,2′-azino-bis; 3-ethylbenzothiazoline-6-sulphonic acid), hydroxyl radical and superoxide radical scavenging activity (SAS). Scavenging activities were assayed within a concentration range of 25–75 ng ml−1. The antibacterial activities with MIC were investigated against two Gram-positive bacteria Streptococcus mutans (MTCC 497) and S. pyogens (MTCC 1926); three Gram negative bacteria Vibrio cholerae (MTCC 3906), Shigella flexneri (MTCC 1457) and Salmonella typhii (MTCC 1252). ZnO nanoparticles synthesized by the polyol method showed better MIC values against both Gram-positive and Gram-negative bacteria as compared to particles synthesized by aqueous precipitation method. Present study demonstrates the successful synthesis of ZnO nanoparticles with antioxidant property and significant broad spectrum antibacterial activity against several clinical bacterial pathogens.

Transparent Dispersions of Monodispersed ZnO Nanoparticles with Ultrahigh Content and Stability for Polymer Nanocomposite Film with Excellent Optical Properties

A novel route was proposed for the synthesis of transparent dispersions of monodispersed zinc oxide (ZnO) nanoparticles via a high-gravity reactive precipitation combined with “inorganic–organic successive layer coating” method. The as-prepared nanodispersion had a uniform particle size of about 4 nm, high stability of over 12 months, and still remained transparent at ultrahigh solid content of 60 wt %. Highly transparent polylactide (PLA)/ZnO and PLA/ZnO/cesium doped tungsten oxide CsxWO3 nanocomposite films were further fabricated by a simple solution mixing method. Because of the uniform dispersion of nanoparticles, PLA/ZnO films could maintain the same visible transmittance as pure PLA film even when ZnO content reached 60 parts per hundred of PLA resin by weight (phr). Furthermore, the films could shield almost 100% ultraviolet radiation at ZnO content of up to 5 phr, thereby realizing good antiaging property. Besides their excellent transparency and UV-shielding property, PLA/ZnO/CsxWO3 films could ...

Large-scale synthesis of porous graphene through nanoscale carbothermal reduction etching

Porous graphene, which features nanoscaled pores on the sheets, has shown great potential in many technologically important industries. However, the conversional approaches for the synthesis of porous graphene including high-energy techniques and template etching/growth methods are generally conducted on substrates with high cost and low throughput. Herein, we demonstrate a general and scalable synthetic method for porous graphene via carbothermal reduction reaction using monodisperse zinc oxide nanoparticles. The results indicate that ZnO nanoparticles were first attached on graphene oxide nanosheets by electrostatic interaction, and then undergone a carbothermal reduction reaction at 800 °C to produce the pores on the sheets. While graphene oxide nanosheets were thermally reduced to graphene, all the by-products (carbon monoxide, carbon dioxide, and zinc) escaped from the final products simultaneously. The characterizations of the obtained porous graphene reveal that the pore size is about 11 nm, larger than that of ZnO nanoparticles (~5 nm), which is ascribed to the aggregation of ZnO nanoparticles (~20 nm) on the graphene oxide sheets. These results show the certain correlation among the sizes of pores, ZnO nanoparticles and ZnO aggregations, which gain insight into the controlling of pore size by choosing suitable etching agent.

Role of polyethyleneimine (PEI) in synthesis of zinc oxide nanoparticles and their cytotoxicity effects

Monodispersed zinc oxide nanoparticles (ZnO-NPs) were synthesized by a simple sol–gel method. In this process, polyethyleneimine (PEI) was used as a polymeric matrix and mild reaction conditions. The PEI acted as a stabilizing or capping agent and polymeric template for preparing ZnO-NPs. The ZnO-NPs were successfully grown at different calcination temperatures, and their crystallite structures were characterized using various methods, including TEM, PXRD, FTIR, and TGA/DTA techniques. The PXRD analysis revealed wurtzite hexagonal ZnO with preferential orientation at (101) reflection plane. Spherical ZnO-NPs were synthesized and its TEM image showed the formation of nanopowders in size of about 25nm, while dose dependent toxicity with non-toxic effect of concentration below 6.25µg/mL was observed in the studies of in vitro cytotoxicity on neuro2A cells.

Magic Sized Clusters in ZnO Nanoparticle Formation – an in-situ PDF study

Semiconductor nanoparticles (NP) such as zinc oxide (ZnO) are commonly produced in sol-gel processes. The final NP powders are well characterized with respect to their crystallinity, which fundamentally governs their physical and chemical properties. Nevertheless, the nucleation process and the evolution of crystallinity of the nucleating NPs is not yet understood [1]. With the advent of the Rapid Acquisition Pair Distribution Function (PDF) method, time-resolved PDF studies have become possible, and the distinction between molecular clusters and nanoparticles in 1 M aqueous solutions of metal oxide NPs [2] has been demonstrated. However, nucleation in dilute sol-gel processes in more complex organic solutions remains untackled [1]. Our experiments are, to our knowledge, the first in-situ PDF studies in organic solvents. We used a 30 mM ethanolic solution of zinc acetate dihydrate. Several hours after the addition of the organic base tetramethylammonium hydroxide, monodisperse ZnO powders can be obtained. However, directly upon the base addition primary tetrahedral precursors Zn4OAc6 form. Approx. 1 hour later, they evolve into stable magic sized clusters (MSC) of 1.3 nm diameter and wurtzitic structure. Though known to exist for II-VI semiconductor NP such as CdSe [3], MSCs have not been demonstrated for ZnO before. With ongoing reaction time, the final spherical NPs of 2.5 nm diameter evolve at the expense of the MSCs and exist for several hours without undergoing further growth. SAXS studies confirm the PDF data. Fig. 1 shows the experimental PDFs and their fits. The fits are multiphase models of the precursor, the MSC and NP. The solvent shows intermolecular ordering effects whose contribution to the PDF was modelled by a low-frequency wave function. The MSC and NP sketches show a view along the crystallographic c-axis. Based upon these state-of-the art in-situ PDF studies, we suggest a nucleation model based on the existence of magic-sized clusters.

Tailoring of growth and properties: a benign approach to synthesise ZnO nanostructures without growth-directing agents

Achieving rational control over the growth of nanostructures without employing growth-directing agents has received considerable attention. Such approaches are a key to obtaining nanomaterials pure enough for desired applications. We report on the novel synthesis of nearly monodisperse zinc oxide nanocrystals, randomly oriented nanocrystals in spherical aggregates, and flower-like aggregates of oriented nanocrystals through a benign, ultrasonic assisted approach. It is shown that crystals of defined dimensions and morphology can be obtained by controlling the temperature of the sonicated solution of a well-chosen precursor. The powder samples resulting from sonochemical synthesis are thoroughly characterized by powder x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and by Raman and UV-vis spectroscopies. The results are explained by invoking the phenomena of randomly oriented aggregation, oriented attachment, and ripening, as amply supported by electron microscopy. Photoluminescence spectra of these various ZnO nanostructures reveal a strong dependence on the dimensions and morphology of the nanostructures, indicating that such luminescence can be tailored suitably.

Effect of Eosin Y Dye on Electrical Properties of ZnO Film Synthesized by Sol–Gel Technique

This paper presents preparation of zinc oxide (ZnO) nanoparticles by the sol–gel technique. ZnO films were prepared by the doctor-blade method, and the resulting films were sensitized with eosin Y (EY) by immersing them in a solution of EY dye in ethanol. The prepared samples were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transmission infrared spectroscopy, and ultraviolet (UV)–visible spectroscopy. The monodispersed ZnO nanocrystals possess a wurtzite hexagonal structure with diameter of ∼7 nm to 17 nm as observed by XRD and TEM analyses. The absorption spectrum of EY-dye-sensitized ZnO (ZnO/EY) film is slightly broadened, with a red-shift in the peak position compared with the absorbance spectrum of the dye in ethanol. Measurements of electrical parameters such as dark conductivity and photoconductivity were carried out at different temperatures. Transient photoconductivity was also studied at different temperatures to investigate the photoconduction mechanism. The photosensitivity of the ZnO/EY film is higher than that of the ZnO film. Hall measurements show n-type behavior for both samples. The visible absorption spectrum and high photosensitivity of the ZnO/EY films support their potential use as photoanode materials in dye-sensitized solar cells and optoelectronic devices.

Synthesis and enhanced mechanical properties of nano Zinc Oxide in Polyvinyl alcohol and Polyvinyl pyrollidone composite film

Zinc oxide nanoparticles have been synthesized by chemical reaction method. Polyvinyl alcohol (PVA) composite film filled with nanometric, monodispersed zinc oxide nano particles prepared by PVA solution and nanozinc oxide. Polymer blend with ZnO nanoparticle composite film has prepared by casting technique. The property of nano composites depends greatly on the chemistry of polymer matrices. The dispersion of nano particles in the polymer matrices is a general prerequisite for achieving desired mechanical and physical properties. Particular attention is paid on the structural and mechanical properties of a composite film by SEM and Measurement of tensile properties. The results also shows that, the ZnO NPs were uniformly dispersed in the polymer matrix and the particles remained their original size (20-150 nm) before incorporate in to the polymer matrix.

Cost effective and Monodispersed Zinc Oxide Nanoparticles Synthesis and their Characterization

Zinc Oxide (ZnO) Nanoparticles are most widely used in the field of Biotechnology and Nanoelectronics due to their good transparency, high electron mobility, strong room-temperature luminescence and nontoxic. Due to their increasing demand, highly specified and monodispersed nanoparticles formation is a revolutionary field. Here ZnO nanoparticles are prepared by modified sol-gel method and are characterized using UV-Vis Absorption Spectroscopy, X-ray Diffraction and Scanning Electron Microscopy (SEM). Modified sol-gel mediated ZnO nanoparticles are proved to synthesize the highly stable, monodispersed and cost effective nanoparticles. The results are quite appreciable and wide band gap- long range ordered ZnO nanoparticles are obtained than the conventional route.

Cost effective and Monodispersed Zinc Oxide Nanoparticles Synthesis and their Characterization

Zinc Oxide (ZnO) Nanoparticles are most widely used in the field of Biotechnology and Nanoelectronics due to their good transparency, high electron mobility, strong room-temperature luminescence and nontoxic. Due to their increasing demand, highly specified and monodispersed nanoparticles formation is a revolutionary field. Here ZnO nanoparticles are prepared by modified sol-gel method and are characterized using UV-Vis Absorption Spectroscopy, X-ray Diffraction and Scanning Electron Microscopy (SEM). Modified sol-gel mediated ZnO nanoparticles are proved to synthesize the highly stable, monodispersed and cost effective nanoparticles. The results are quite appreciable and wide band gap- long range ordered ZnO nanoparticles are obtained than the conventional route.

MORPHOLOGICAL CONTROL OF METAL OXIDE-DOPED ZINC OXIDE AND APPLICATION TO COSMETICS

Zinc oxide shows excellent transparency and ultraviolet radiation shielding ability, and is used for various cosmetics.1–3 However, it possesses high catalytic activity and lower dispersibility. Therefore, spherical particles of zinc oxide have been synthesized by soft solution reaction using zinc nitrate, ethylene glycol, sodium hydroxide and triethanolamine as starting materials. After dissolving these compounds in water, the solution was heated at 90°C for 1 h to form almost mono-dispersed spherical zinc oxide particles. The particle size changed depending on zinc ion concentration, ethylene glycol concentration and so on. Furthermore, with doping some metal ions, the phtocatalytic activity could be decreased. The obtained monodispersed metal ion-doped spherical zinc oxides showed excellent UV shielding ability and low photocatalytic activity. Therefore, they are expected to be used as cosmetics ingredients.

Formation of zinc oxide nanoparticles of different shapes in water-in-oil microemulsion

In this paper we report the direct synthesis of pure monodispersed zinc oxide nanoparticles of different shapes by basic hydrolysis of zinc nitrate with suitable control of the reactant concentrations in the water in oil microemulsion of Triton X-100/hexanol/cyclohexane. Pure hexagonal wurtzite zinc oxide nanoparticles were obtained in each case. Reaction with a weak base ammonium hydroxide yields highly monodispersed nearly spherical nanoparticles in the range 2.1–7.7 nm whereas reaction with strong base sodium hydroxide forms nanorods at lower reactant concentration and larger rectangular nanoparticles at higher reactant concentration. Optical properties of these zinc oxide nanoparticles were studied at room temperature by taking the optical absorption and luminescence spectra. All samples show strong absorption in the UV range and are nearly transparent in the visible range. The band gap luminescence is predominant in the zinc oxide nanoparticles prepared by this technique, along with two smaller defect induced peaks at 426–488 nm,while the green defect induced luminescence (between 500 and 550 nm) typical of zinc oxide is strongly quenched.

レーザー蒸発法による単分散酸化亜鉛量子ドットのサイズ選別合成と光学特性

レーザー蒸発法による単分散酸化亜鉛量子ドットのサイズ選別合成と光学特性