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1

Preparation of magnetic spinel ferrite core\\/shell nanoparticles: Soft ferrites on hard ferrites and vice versa  

Microsoft Academic Search

Hard\\/soft CoFe2O4\\/ZnFe2O4 and soft\\/hard ZnFe2O4\\/CoFe2O4 core\\/shell nanoparticles were prepared by combining high-temperature thermolysis of metal oxide precursors with seed-mediated growth. Magnetic properties of the core\\/shell nanoparticles were compared to those of individual CoFe2O4 and ZnFe2O4 nanoparticles of similar size prepared by the same method. The structure of the core\\/shell materials was established using a combination of X-ray and neutron powder

Ombretta Masala; Darin Hoffman; Nalini Sundaram; Katharine Page; Thomas Proffen; Gavin Lawes; Ram Seshadri

2006-01-01

2

Preparation of cobalt ferrite nanoparticles via a novel solvothermal approach using divalent iron salt as precursors  

SciTech Connect

Graphical abstract: CoFe{sub 2}O{sub 4} nanoparticles are obtained via solvothermal approach using Fe{sup 2+} salt as iron resource. The magnetic properties can be modified by some additives. Display Omitted Highlights: ? CoFe{sub 2}O{sub 4} nanoparticles are synthesized by a facile one-step novel solvothermal method. ? The system is firstly performed in water–glycol mixture solvent with an ordinary air surrounding. ? The ferrous ions are used as iron source without adding oxidant. ? It is firstly found the low-coercivity CoFe{sub 2}O{sub 4} nanoparticles can be obtained with the help of some additives in the synthesis system. -- Abstract: Cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles are synthesized by a facile novel solvothermal method. The reactions are firstly performed in water–glycol system and Fe{sup 2+} salt is used as iron source without oxidant help. Some factors influenced the reactions, including temperature, reaction time, additives, are investigated. The samples are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), respectively. The magnetic properties of some samples are detected by vibrating sample magnetometry techniques (VSM). It is firstly found that the magnetism of cobalt ferrites nanomaterials can be modified by some additives. The coercivity of CoFe{sub 2}O{sub 4} nanoparticles evidently decreases from 600 to 50 Oe in the presence of PEG-4000 in the system.

Ma, Jie, E-mail: majie0203ch@hotmail.com [College of Science, University of Shanghai for Science and Technology (China) [College of Science, University of Shanghai for Science and Technology (China); Green Bio- and Eco-Chem. Eng. Lab, University of Shanghai for Science and Technology (China); Zhao, Jiantao; Li, Wenlie [College of Science, University of Shanghai for Science and Technology (China)] [College of Science, University of Shanghai for Science and Technology (China); Zhang, Shuping [College of Science, University of Shanghai for Science and Technology (China) [College of Science, University of Shanghai for Science and Technology (China); Green Bio- and Eco-Chem. Eng. Lab, University of Shanghai for Science and Technology (China); Tian, Zhenran; Basov, Sergey [College of Science, University of Shanghai for Science and Technology (China)] [College of Science, University of Shanghai for Science and Technology (China)

2013-02-15

3

Synthesis and magnetic properties of cobalt ferrite (CoFe 2O 4) nanoparticles prepared by wet chemical route  

Microsoft Academic Search

Magnetic nanoparticles of cobalt ferrite have been synthesized by wet chemical method using stable ferric and cobalt salts with oleic acid as the surfactant. X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) confirmed the formation of single-phase cobalt ferrite nanoparticles in the range 15–48nm depending on the annealing temperature and time. The size of the particles increases with annealing temperature

K. Maaz; Arif Mumtaz; S. K. Hasanain; Abdullah Ceylan

2007-01-01

4

Oleate Coated Magnetic Cores Based on Magnetite, Zn Ferrite and Co Ferrite Nanoparticles - Preparation, Physical Characterization and Biological Impact on Helianthus Annuus Photosynthesis  

SciTech Connect

Sodium oleate was used as coating shell for magnetite, Zn ferrite and Co ferrite powders to stabilize them in the form of aqueous magnetic suspensions. The physical characterization was carried out by applying X-ray diffraction and magnetization measurements. Both crystallite size and magnetic core diameter ranged between 7 and 11 nm. The influence of magnetic nanoparticle suspensions (corresponding to magnetic nanoparticle levels of 10{sup -14}-10{sup -15}/cm{sup 3}) on sunflower seedlings was studied considering the changes in the photosynthesis pigment levels. Similar responses were obtained for magnetite and cobalt ferrite nanoparticle treatment consisting in the apparent inhibition of chlorophyll biosynthesis while for zinc ferrite nanoparticles some concentrations seemed to have stimulatory effects on the chlorophylls as well as on the carotene levels. But the chlorophyll ratio was diminished in the case of all three types of magnetic nanoparticles meaning their slight negative effect on the light harvesting complex II (LHC II) from the chloroplast membranes and consequently on the photosynthesis efficiency.

Ursache-Oprisan, Manuela; Foca-nici, Ecaterina; Cirlescu, Aurelian; Caltun, Ovidiu; Creanga, Dorina [Al. I. Cuza' University, Faculty of Physics, 11A Blvd.Copou, 700506, Iasi (Romania)

2010-12-02

5

Preparation of magnetic photocatalyst nanoparticles—TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite—and its photocatalytic activity influenced by silica interlayer  

SciTech Connect

Highlights: ? TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite acts as magnetic photocatalyst nanoparticle. ? SiO{sub 2} interlayer is used to prevent electron migration between photocatalyst and magnetic core. ? TiO{sub 2}/Mn–Zn ferrite without SiO{sub 2} interlayer shows poor magnetic and photocatalytic property. -- Abstract: A magnetic photocatalyst, TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite, was prepared by stepwise synthesis involving the co-precipitation of Mn–Zn ferrite as a magnetic core, followed by a coating of silica as the interlayer, and titania as the top layer. The particle size and distribution of magnetic nanoparticles were found to depend on the addition rate of reagent and dispersing rate of reaction. The X-ray diffractometer and transmission electron microscope were used to examine the crystal structures and the morphologies of the prepared composites. Vibrating sample magnetometer was also used to reveal their superparamagnetic property. The UV–Vis spectrophotometer was employed to monitor the decomposition of methylene blue in the photocatalytic efficient study. It was found that at least a minimum thickness of the silica interlayer around 20 nm was necessary for the inhibition of electron transference initiated by TiO{sub 2} and Mn–Zn ferrite.

Laohhasurayotin, Kritapas, E-mail: kritapas@nanotec.or.th [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)] [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand); Pookboonmee, Sudarat; Viboonratanasri, Duangkamon; Kangwansupamonkon, Wiyong [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)] [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)

2012-06-15

6

Preparation, characterization, in vivo and in vitro studies of arsenic trioxide Mg-Fe ferrite magnetic nanoparticles  

PubMed Central

Aim: MgFe2O4 magnetic nanoparticle composed of As2O3 (As2O3-MNPs) were prepared and their in vitro and in vivo characteristics were studied. Methods: The solvent-displacement method was applied for preparation of the nanoparticle using Poly-D,L-lactic-co-glycolic acid(PLGA). The characteristics studies of the products included magnetic response, morphology (transmission electron microscopy and scanning electron microscopy), entrapment efficiency, drug loading, particle sizes, zeta potential, in vitro drug release and tissue magnetic targeting. Nanoparticle cytotoxicity to Saos-2 cells was investigated using the MTT assay. To guide the external magnetic field in the liver, the concentration of As2O3 in the liver and kidney was measured using an atomic fluorescence spectrometer after injecting As2O3-MNPs into the caudal veins of mice. Results: The As2O3-MNPs were approximately spherical. The average diameter, drug loading, entrapment efficiency and zeta potential of As2O3-MNPs were 109.9 nm, 10.08%, 82.16%, and ?14.33 mV, respectively. The specific saturation magnetism was 8.65 emu/g. In vivo, the concentration of As2O3 in the liver was significantly higher than that in the non-magnetic group. While the concentration of As2O3 in the kidney was lower than that in the non-magnetic group. The Cmax in liver tissue in the magnetic group was 30.65 ?g/g, which was 4.17 times the drug concentration in the same group in kidney tissue (7.35 ?g/g) and 2.88 times the concentration of drug (10.66 ?g/g) in the liver tissue of the non-magnetic group. Conclusion: The PLGA polymer-loaded magnetic nanoparticle composed of arsenic trioxide can be magnetically targeted well and applied in biomedicine. PMID:19960013

Yang, Guo-fu; Li, Xiang-hui; Zhao, Zhe; Wang, Wen-bo

2009-01-01

7

Structural characterization and magnetic properties of superparamagnetic zinc ferrite nanoparticles synthesized by the coprecipitation method  

NASA Astrophysics Data System (ADS)

Single phase zinc ferrite (ZnFe2O4) nanoparticles have been prepared by the coprecipitation method without any subsequent calcination. The effects of precipitation temperature in the range 20-80 °C on the structural and the magnetic properties of zinc ferrite nanoparticles were investigated. The crystallite size, microstructure and magnetic properties of the prepared nanoparticles were studied using X-ray diffraction (XRD), Fourier transmission infrared spectrum, transmission electron microscope (TEM), energy dispersive X-ray spectrometer and vibrating sample magnetometer. The XRD results showed that the coprecipitated nanoparticles were single phase zinc ferrite with mixture of normal and inverse spinel structures. Furthermore, ZnFe2O4 nanoparticles have the crystallite size in the range 5-10 nm, as confirmed by TEM. The magnetic measurements exhibited that the zinc ferrite nanoparticles synthesized at 40 °C were superparamagnetic with the maximum magnetization of 7.3 emu/g at 10 kOe.

Raeisi Shahraki, R.; Ebrahimi, M.; Seyyed Ebrahimi, S. A.; Masoudpanah, S. M.

2012-11-01

8

Magnetoabsorption and magnetic hysteresis in Ni ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Nickel ferrite nanoparticles were prepared by a modified sol-gel technique employing coconut oil, and then annealed at different temperatures in 400-1200 °C range. This route of preparation has revealed to be one efficient and cheap technique to obtain high quality nickel ferrite nanosized powder. Sample particles sizes obtained with XRD data and Scherrer's formula lie in 13 nm to 138 nm, with increased size with annealing temperature. Hysteresis loops have been obtained at room temperature with an inductive method. Magnetic field induced microwave absorption in nanoscale ferrites is a recent an active area of research, in order to characterize and explore potential novel applications. In the present work microwave magnetoabsorption data of the annealed nickel ferrite nanoparticles are presented. These data have been obtained with a system based on a network analyzer that operates in the frequency range 0 - 8.5 GHz. At fields up to 400 mT we can observe a peak according to ferromagnetic resonance theory. Sample annealed at higher temperature exhibits different absorption, coercivity and saturation magnetization figures, revealing its multidomain character.

Hernández-Gómez, P.; Muñoz, J. M.; Valente, M. A.; Torres, C.; de Francisco, C.

2013-01-01

9

Effects of oleic acid surface coating on the properties of nickel ferrite nanoparticles/PLA composites.  

PubMed

Nickel ferrite nanoparticles with or without oleic acid surface coating were mixed with poly(D,L-lactide) (PLA) by double emulsion method. If the nanoparticles were prepared without oleic acid coating, they adsorbed on the PLA surface. If the nanoparticles were coated with oleic acid, they could be readily encapsulated within the PLA microspheres. A slight depression in glass transition temperature was found in all composites and it could be related to the interfacial energies between nanoparticles and PLA. Optimum mixed composite was achieved by reducing interfacial energy. However, loading capacity was limited in this composite. Increasing the amount of nickel ferrite nanoparticles was not useful to increase loading capacity. Cytotoxicity of the composite decreased significantly when nickel ferrite nanoparticles were effectively encapsulated in PLA microspheres. PMID:18980192

Yin, Hong; Chow, Gan-Moog

2009-11-01

10

Magnetization temperature dependence and freezing of surface spins in magnetic fluids based on ferrite nanoparticles  

Microsoft Academic Search

Manganese and copper ferrite nanoparticles, in the size range 3.3-10.4 nm, are prepared by a hydrothermal coprecipitation process and peptized in aqueous solution. The thermal dependence of the high field magnetization is investigated in the dilute regime and the observed properties can be attributed to individual particles. Our results show that, at low temperatures, the structure of our nanoparticles can

R. Aquino; J. Depeyrot; M. H. Sousa; F. A. Tourinho; E. Dubois; R. Perzynski

2005-01-01

11

Magnetic resonance of ferrite nanoparticles  

Microsoft Academic Search

Ferromagnetic resonance (FMR) experiments at 9.26GHz on non-interacting maghemite (?-Fe2O3) nanoparticles of ferrofluids are performed as a function of temperature (3.5–300K) and particle diameter (4.8–10nm). The orientational mobility of the particles inside the fluid is employed to monitor the orientational distribution of the anisotropy axes by solidifying the MF matrix under the external field. On those textured suspensions, angular analysis

F. Gazeau; J. C Bacri; F. Gendron; R. Perzynski; Yu. L Raikher; V. I. Stepanov; E. Dubois

1998-01-01

12

Optimizing hysteretic power loss of magnetic ferrite nanoparticles  

E-print Network

This thesis seeks to correlate hysteretic power loss of tertiary ferrite nanoparticles in alternating magnetic fields to trends predicted by physical models. By employing integration of hysteresis loops simulated from ...

Chen, Ritchie

2013-01-01

13

Transition metal-substituted cobalt ferrite nanoparticles for biomedical applications.  

PubMed

Transition metals of copper, zinc, chromium and nickel were substituted into cobalt ferrite nanoparticles via a sol-gel route using citric acid as a chelating agent. The microstructure and elemental composition were characterized using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Phase analysis of transition metal-substituted cobalt ferrite nanoparticles was performed via X-ray diffraction. Surface wettability was measured using the water contact angle technique. The surface roughness of all nanoparticles was measured using profilometry. Moreover, thermogravimetric analysis and differential scanning calorimetry were performed to determine the temperature at which the decomposition and oxidation of the chelating agents took place. Results indicated that the substitution of transition metals influences strongly the microstructure, crystal structure and antibacterial property of the cobalt ferrite nanoparticles. PMID:23137676

Sanpo, Noppakun; Berndt, Christopher C; Wen, Cuie; Wang, James

2013-03-01

14

Ionic magnetic fluid based on cobalt ferrite nanoparticles: Influence of hydrothermal treatment on the nanoparticle size  

Microsoft Academic Search

Magnetic fluid based on cobalt ferrite nanoparticles was obtained using a hydrothermal treatment added to the Massart procedure. This treatment increases the average size of the nanoparticles from 11.9 to 18.7nm and also improves the dispersity and crystallinity of the cobalt ferrite particles. The nanoparticles obtained after the hydrothermal treatment were dispersed in aqueous solvent by the classical procedure for

Valérie Cabuil; Vincent Dupuis; Delphine Talbot; Sophie Neveu

2011-01-01

15

Synthesis of core\\/shell spinel ferrite\\/carbon nanoparticles with enhanced cycling stability for lithium ion battery anodes  

Microsoft Academic Search

Monodispersed core\\/shell spinel ferrite\\/carbon nanoparticles are formed by thermolysis of metal (Fe3+, Co2+) oleates followed by carbon coating. The phase and morphology of nanoparticles are characterized by x-ray diffraction and transmission electron microscopy. Pure Fe3O4 and CoFe2O4 nanoparticles are initially prepared through thermal decomposition of metal–oleate precursors at 310 °C and they are found to exhibit poor electrochemical performance because

Yun-Ho Jin; Seung-Deok Seo; Hyun-Woo Shim; Kyung-Soo Park; Dong-Wan Kim

2012-01-01

16

Microwave-hydrothermal synthesis of perovskite bismuth ferrite nanoparticles  

Microsoft Academic Search

Hydrothermal microwave method (HTMW) was used to synthesize crystalline bismuth ferrite (BiFeO3) nanoparticles (BFO) in the temperature of 180°C with times ranging from 5min to 1h. BFO nanoparticles were characterized by means of X-ray analyses, FT-IR, Raman spectroscopy, TG-DTA and FE-SEM. X-ray diffraction results indicated that longer soaking time was benefit to refraining the formation of any impurity phases and

G. Biasotto; A. Z. Simões; C. R. Foschini; M. A. Zaghete; J. A. Varela; E. Longo

2011-01-01

17

Magnetic properties of Mg-ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

MgFe 2O 4 nanoparticles encapsulated in amorphous SiO 2 were prepared by means of a wet chemical method, and the magnetic properties were studied. The diameters of these particles were estimated from X-ray diffraction patterns as ranging from 3 to 8 nm. Magnetization measurements were carried out for each sample under a ±50 kOe field. The blocking temperature, Tb, was determined to be around 30 K from the temperature dependence of both the field-cooled (FC) and the zero-field-cooled (ZFC) magnetization. The M- H curve indicated the presence of ferromagnetic behavior with hysteresis below the blocking temperature, Tb. A large coercive force of about 1000 Oe was found at 5 K. Heat treatment was carried out for the prepared samples using an electric furnace in air. A clear difference in magnetization was found between the quenched samples and annealed samples. This phenomenon suggests that the Mg 2+ ions in the spinel structure would be randomly distributed into both the A- and the B-site.

Ichiyanagi, Y.; Kubota, M.; Moritake, S.; Kanazawa, Y.; Yamada, T.; Uehashi, T.

2007-03-01

18

Effect of heat treatment on microwave absorption properties of Ni-Zn-Mg-La ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Spinel structure Ni-Zn-Mg-La ferrites have been prepared by the sol-gel route and investigated as a radar absorbing material (RAM) in a frequency range of 1-18 GHz. The structure and morphological studies on the nanoparticles of the ferrites have been carried out using X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The complex permeability and complex permittivity are measured by a network analyzer. The electromagnetic wave loss and microwave absorbing property are studied as a function of frequency, annealing temperature and thickness of the absorber. The results indicate that electromagnetic wave loss of the ferrite only annealed at 850 °C shows two peaks. The reflection loss varies with the change of the annealing temperature. The absorber annealed at 850 °C exhibits the best microwave absorbing properties, which is suitable for microwave absorption materials.

Liu, Yi; Wei, Shicheng; Xu, Binshi; Wang, Yujiang; Tian, Haoliang; Tong, Hui

2014-01-01

19

Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses  

PubMed Central

Summary Oriented attachment has created a great debate about the description of crystal growth throughout the last decade. This aggregation-based model has successfully described biomineralization processes as well as forms of inorganic crystal growth, which could not be explained by classical crystal growth theory. Understanding the nanoparticle growth is essential since physical properties, such as the magnetic behavior, are highly dependent on the microstructure, morphology and composition of the inorganic crystals. In this work, the underlying nanoparticle growth of cobalt ferrite nanoparticles in a bioinspired synthesis was studied. Bioinspired syntheses have sparked great interest in recent years due to their ability to influence and alter inorganic crystal growth and therefore tailor properties of nanoparticles. In this synthesis, a short synthetic version of the protein MMS6, involved in nanoparticle formation within magnetotactic bacteria, was used to alter the growth of cobalt ferrite. We demonstrate that the bioinspired nanoparticle growth can be described by the oriented attachment model. The intermediate stages proposed in the theoretical model, including primary-building-block-like substructures as well as mesocrystal-like structures, were observed in HRTEM measurements. These structures display regions of substantial orientation and possess the same shape and size as the resulting discs. An increase in orientation with time was observed in electron diffraction measurements. The change of particle diameter with time agrees with the recently proposed kinetic model for oriented attachment. PMID:24605288

Hetaba, Walid; Wissbrock, Marco; Loffler, Stefan; Mill, Nadine; Eckstadt, Katrin; Dreyer, Axel; Ennen, Inga; Sewald, Norbert; Schattschneider, Peter; Hutten, Andreas

2014-01-01

20

Mössbauer studies of nanosized ferrites prepared by the combustion of metal nitrates oxalyl dihydrazide solutions  

NASA Astrophysics Data System (ADS)

Alkaline earth metal ferrites have been prepared by combustion of redox mixtures containing metal nitrates and oxalyl dihydrazide (ODH) at 673 K. On rapid heating, ODH metal nitrate mixture undergoes an abrupt exothermic redox chemical reaction that facilitates atomic scale mixing of cations. This leads to the formation of stoichiometrically pure and single-phase nanoparticle ferrites at comparatively reduced temperature (400°C) and in less time than possible by the conventional ceramic method. Because of their different cationic size, polarizability etc., alkaline earth metal cations yield different type of ferrites i.e. MFe2O4 (M = Mg, Ba), Ca2Fe2O5 and SrFe12O19.

Gandotra, Karun; Randhawa, B. S.

2008-07-01

21

Comparison effects and electron spin resonance studies of ?-Fe2O4 spinel type ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

?-Fe2O4 spinel type ferrite nanoparticles have been synthesized by cetyltrimethylammonium bromide (CTAB) and ethylenediaminetetraacetic acid (EDTA) assisted hydrothermal route by using NaOH solution. Electron spin resonance (ESR/EPR) measurements of ?-Fe2O4 nanoparticles have been performed by a conventional x-band spectrometer at room temperature. The comparison effect of nanoparticles prepared by using CTAB and EDTA in different ?-doping on the structural and morphological properties have been investigated in detail. The effect of EDTA-assisted synthesis for ?-Fe2O4 nanoparticles are refined, and thus the spectroscopic g-factor are detected by using ESR signals. These samples can be considered as great benefits for magnetic recording media, electromagnetic and drug delivery applications.

Bayrakdar, H.; Yalç?n, O.; Cengiz, U.; Özüm, S.; Anigi, E.; Topel, O.

2014-11-01

22

Comparison of surface effects in SiO2 coated and uncoated nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic properties of uncoated and silica coated nickel ferrite nanoparticles of comparable sizes have been studied in detail. Silica coated and uncoated nanoparticles were prepared by sol-gel and co-precipitation methods, respectively. Average crystallite size determined by X-ray diffraction is 12 nm and 14 nm for the silica coated and uncoated nanoparticles, respectively. Normalized saturation magnetization value of the coated nanoparticles was found to be lower than of uncoated nanoparticles, while a comparable small coercivity is observed for both the samples. Zero field cooled/field cooled (ZFC/FC) measurements reveal that the average blocking temperature (TB) of coated nanoparticles is lower than of the uncoated nanoparticles and is shifted to lower temperatures at high field. Thermoremanent magnetization (TRM) measurement indicates that the relaxation of coated nanoparticles have not been influenced very much with increasing cooling field as compared to uncoated nanoparticles and is attributed to enhanced surface effects in coated nanoparticles. The main source of enhanced surface effects in the coated nanoparticles is foremost disordered surface spins due to silica matrix. Temperature dependent AC susceptibility exhibits two peaks for the coated nanoparticles' sample. First peak corresponds to blocking of huge core spin while second peak at lower temperature is may be due to enhanced surface effects (spin-glass behavior). All these findings such as lower saturation magnetization, faster shift of blocking temperature at high field, small effect of high magnetic field on magnetic relaxation, low temperature out-of-phase AC susceptibility peak for the coated nanoparticles signify enhanced surface effects in them as compared to uncoated nanoparticles.

Nadeem, K.; Krenn, H.; Sarwar, W.; Mumtaz, M.

2014-01-01

23

The Effect of Alkali Concentration on the Structural and Magnetic Properties of Mn-Ferrite Nanoparticles Prepared via the Coprecipitation Method  

NASA Astrophysics Data System (ADS)

MnFe2O4 nanoparticles were synthesized using the coprecipitation method under two different NaOH concentration settings as reaction agents at 355 K (82 °C). Structural and morphological properties of the nanoparticles were examined using X-ray diffraction and a scanning electron microscope. The decrease of NaOH concentration led to the increase of particle size. This result contradicts two recently published reports. Also, the decrease of NaOH concentration led to more crystallinity and a narrower particle size distribution. The results were evaluated from a chemical point of view and were based on the supersaturation level, which was influenced by alkali concentration. It was concluded that the higher NaOH concentration led to a more rapid nucleation and more random cation distribution. The magnetic properties of the nanoparticles examined by permeameter and faraday-balance equipment were consistent with the structural and morphological properties of the particles.

Pourbafarani, Somayeh

2014-09-01

24

Preparation of TEM samples of ferritic alloys  

Microsoft Academic Search

We describe techniques for electropolishing irradiated ferritic specimens for examination under the TEM in situations where the foil quality is of utmost importance. First, we describe some modifications to the standard technique for making plan-view specimens aimed at optimizing the foil quality. Second, we describe a technique for making plan-view specimens from a region of buried damage in a specimen

Z. Yao; S. Xu; M. L. Jenkins; M. A. Kirk

2008-01-01

25

Preparation of TEM samples of ferritic alloys.  

PubMed

We describe techniques for electropolishing irradiated ferritic specimens for examination under the TEM in situations where the foil quality is of utmost importance. First, we describe some modifications to the standard technique for making plan-view specimens aimed at optimizing the foil quality. Second, we describe a technique for making plan-view specimens from a region of buried damage in a specimen irradiated with 2 MeV Fe(+) ions. PMID:18316797

Yao, Z; Xu, S; Jenkins, M L; Kirk, M A

2008-06-01

26

Chemisorption of cyanogen chloride by spinel ferrite magnetic nanoparticles.  

PubMed

Spinel ferrite magnetic nanoparticles, MnFe2O4, NiFe2O4, and CoFe2O4, were synthesized and used as gas-phase adsorbents for the removal of cyanogen chloride from dry air. Fixed-bed adsorption breakthrough experiments show adsorption wave behavior at the leading edge of the breakthrough curve that is not typical of physically adsorbed species. Fourier transform infrared spectroscopy (FTIR) results indicate that CK is reacting with the spinel ferrite surface and forming a carbamate species. The reaction is shown to be a function of the hydroxyl groups and adsorbed water on the surface of the particles as well as the metallic composition of the particles. The surface reaction decreases the remnant and saturation magnetism of the MnFe2O4 and CoFe2O4 particles by approximately 25%. PMID:23540752

Glover, T Grant; DeCoste, Jared B; Sabo, Daniel; Zhang, Z John

2013-05-01

27

Preparation of highly anisotropic cobalt ferrite/silica microellipsoids using an external magnetic field.  

PubMed

Magnetic cobalt ferrite/silica microparticles having both an original morphology and an anisotropic nanostructure are synthesized through the use of an external magnetic field and nanoparticles characterized by a high magnetic anisotropy. The association of these two factors implies that the ESE (emulsion and solvent evaporation) sol-gel method employed here allows the preparation of silica microellipsoids containing magnetic nanoparticles aggregated in large chains. It is clearly shown that without this combination, microspheres characterized by an isotropic distribution of the magnetic nanoparticles are obtained. While the chaining of the cobalt ferrite nanoparticles inside the silica matrix is related to the increase of their magnetic dipolar interactions, the ellipsoidal shape of the microparticles may be explained by the elongation of the sol droplets in the direction of the external magnetic field during the synthesis. Because of their highly anisotropic structure, these microparticles exhibit permanent magnetic moments, which are responsible, at a larger scale, for the existence of strong magnetic dipolar interactions. Therefore, when they are dispersed in water, the microellipsoids self-assemble into large and irregular chains. These interactions can be reinforced by the use of external magnetic field, allowing the preparation of very large permanent chains. This research illustrates how nanostructured particles exhibiting complex architectures can be elaborated through simple, fast, and low-cost methods, such as the use of external fields in combination with soft chemistry. PMID:25029515

Abramson, Sébastien; Dupuis, Vincent; Neveu, Sophie; Beaunier, Patricia; Montero, David

2014-08-01

28

Oxidative stress mediated apoptosis induced by nickel ferrite nanoparticles in cultured A549 cells.  

PubMed

Due to the interesting magnetic and electrical properties with good chemical and thermal stabilities, nickel ferrite nanoparticles are being utilized in many applications including magnetic resonance imaging, drug delivery and hyperthermia. Recent studies have shown that nickel ferrite nanoparticles produce cytotoxicity in mammalian cells. However, there is very limited information concerning the toxicity of nickel ferrite nanoparticles at the cellular and molecular level. The aim of this study was to investigate the cytotoxicity, oxidative stress and apoptosis induction by well-characterized nickel ferrite nanoparticles (size 26 nm) in human lung epithelial (A549) cells. Nickel ferrite nanoparticles induced dose-dependent cytotoxicity in A549 cells demonstrated by MTT, NRU and LDH assays. Nickel ferrite nanoparticles were also found to induce oxidative stress evidenced by generation of reactive oxygen species (ROS) and depletion of antioxidant glutathione (GSH). Further, co-treatment with the antioxidant L-ascorbic acid mitigated the ROS generation and GSH depletion due to nickel ferrite nanoparticles suggesting the potential mechanism of oxidative stress. Quantitative real-time PCR analysis demonstrated that following the exposure of A549 cells to nickel ferrite nanoparticles, the level of mRNA expressions of cell cycle checkpoint protein p53 and apoptotic proteins (bax, caspase-3 and caspase-9) were significantly up-regulated, whereas the expression of anti-apoptotic proteins (survivin and bcl-2) were down-regulated. Moreover, activities of caspase-3 and caspase-9 enzymes were also significantly higher in nickel ferrite nanoparticles exposed cells. To the best of our knowledge this is the first report showing that nickel ferrite nanoparticles induced apoptosis in A549 cells through ROS generation and oxidative stress via p53, survivin, bax/bcl-2 and caspase pathways. PMID:21382431

Ahamed, Maqusood; Akhtar, Mohd Javed; Siddiqui, Maqsood A; Ahmad, Javed; Musarrat, Javed; Al-Khedhairy, Abdulaziz A; AlSalhi, Mohamad S; Alrokayan, Salman A

2011-05-10

29

Influence of spherical assembly of copper ferrite nanoparticles on magnetic properties: orientation of magnetic easy axis.  

PubMed

The magnetic properties of copper ferrite (CuFe2O4) nanoparticles prepared via sol-gel auto combustion and facile solvothermal method are studied focusing on the effect of nanoparticle arrangement. Randomly oriented CuFe2O4 nanoparticles (NP) are obtained from the sol-gel auto combustion method, while the solvothermal method allows us to prepare iso-oriented uniform spherical ensembles of CuFe2O4 nanoparticles (NS). X-ray diffractometry (XRD), atomic absorption spectroscopy (AAS), infra-red (IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), (57)Fe Mössbauer spectroscopy and vibrating sample magnetometer (VSM) are used to investigate the composition, microstructure and magnetic properties of as-prepared ferrite nanoparticles. The field-dependent magnetization measurement for the NS sample at low temperature exhibits a step-like rectangular hysteresis loop (M(R)/M(S) ~ 1), suggesting cubic anisotropy in the system, whereas for the NP sample, typical features of uniaxial anisotropy (M(R)/M(S) ~ 0.5) are observed. The coercive field (HC) for the NS sample shows anomalous temperature dependence, which is correlated with the variation of effective anisotropy (K(E)) of the system. A high-temperature enhancement of H(C) and K(E) for the NS sample coincides with a strong spin-orbit coupling in the sample as evidenced by significant modification of Cu/Fe-O bond distances. The spherical arrangement of nanocrystals at mesoscopic scale provokes a high degree of alignment of the magnetic easy axis along the applied field leading to a step-like rectangular hysteresis loop. A detailed study on the temperature dependence of magnetic anisotropy of the system is carried out, emphasizing the influence of the formation of spherical iso-oriented assemblies. PMID:24714977

Chatterjee, Biplab K; Bhattacharjee, Kaustav; Dey, Abhishek; Ghosh, Chandan K; Chattopadhyay, Kalyan K

2014-06-01

30

Preparation of transparent conductors ferroelectric memory materials and ferrites  

Microsoft Academic Search

A process for the preparation by electrodeposition of metal oxide film and powder compounds for ferroelectric memory materials and ferrites wherein the metal oxide includes a plurality of metals. The process comprises providing an electrodeposition bath, providing soluble salts of the metals to this bath, electrically energizing the bath to thereby cause formation of a recoverable film of metal on

Raghu Nath Bhattacharya; David S. Ginley

1998-01-01

31

Preparation of transparent conductors ferroelectric memory materials and ferrites  

Microsoft Academic Search

A process is described for the preparation by electrodeposition of metal oxide film and powder compounds for ferroelectric memory materials and ferrites wherein the metal oxide includes a plurality of metals. The process comprises providing an electrodeposition bath, providing soluble salts of the metals to this bath, electrically energizing the bath to thereby cause formation of a recoverable film of

R. N. Bhattacharya; D. S. Ginley

1998-01-01

32

Microwave characterization of magnetically hard and soft ferrite nanoparticles in K-band  

NASA Astrophysics Data System (ADS)

Nano-sized magnetic particles show great promise in improving the performance of microwave absorbers with respect to the corresponding bulk materials. In this paper, magnetically hard and soft ferrite nanoparticles (CoFe2O4 and Fe3O4) having an average size of 14 and 11 nm were prepared by co-precipitation method and characterized in terms of morphology, structure, and magnetic properties. Their permeability and permittivity were measured by a waveguide technique, embedding each sample in a host medium. Their parameters at microwave frequencies were retrieved by comparing different effective medium equations.

Della Pina, C.; Falletta, E.; Ferretti, A. M.; Ponti, A.; Gentili, G. G.; Verri, V.; Nesti, R.

2014-10-01

33

Structural and magnetic investigations of sub-nano Mn-Mg ferrite prepared by wet method  

NASA Astrophysics Data System (ADS)

Manganese-magnesium ferrite nanoparticles Mn1-xMgxFe2O4; 0?x?0.25 were prepared by the co-precipitation route. The samples were characterized by X-ray diffraction (XRD), which confirms the single phase spinel structure. Crystallite size, calculated from the (3 1 1) peak using the Scherrer formula, was found to increase with increasing Mg2+ concentrations and was found to be within the range 3-6 nm. TEM was also used to characterize the microstructure of nanosized Mn1-xMgxFe2O4. Nominal composition of the samples was determined by Atomic Absorption analysis (AA). Hysteresis loops of manganese-magnesium ferrite were obtained at room temperature and revealed lower saturation magnetization values associated with nanocrystalline Mn1-xMgxFe2O4 particles. This behavior was attributed to structural distortion of surface spins compared to that of the bulk one.

Mansour, S. F.

2011-07-01

34

Probing bismuth ferrite nanoparticles by hard x-ray photoemission: Anomalous occurrence of metallic bismuth  

NASA Astrophysics Data System (ADS)

We have investigated bismuth ferrite nanoparticles (˜75 nm and ˜155 nm) synthesized by a chemical method, using soft X-ray (1253.6 eV) and hard X-ray (3500, 5500, and 7500 eV) photoelectron spectroscopy. This provided an evidence for the variation of chemical state of bismuth in crystalline, phase pure nanoparticles. X-ray photoelectron spectroscopy analysis using Mg K? (1253.6 eV) source showed that iron and bismuth were present in both Fe3+ and Bi3+ valence states as expected for bismuth ferrite. However, hard X-ray photoelectron spectroscopy analysis of the bismuth ferrite nanoparticles using variable photon energies unexpectedly showed the presence of Bi0 valence state below the surface region, indicating that bismuth ferrite nanoparticles are chemically inhomogeneous in the radial direction. Consistently, small-angle X-ray scattering reveals a core-shell structure for these radial inhomogeneous nanoparticles.

Chaturvedi, Smita; Sarkar, Indranil; Shirolkar, Mandar M.; Jeng, U.-Ser; Yeh, Yi-Qi; Rajendra, Ranguwar; Ballav, Nirmalya; Kulkarni, Sulabha

2014-09-01

35

Influence of cobalt on structural and magnetic properties of nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Improving the magnetic response of nanocrystalline nickel ferrites is the key issue in high density recording media. A series of cobalt substituted nickel ferrite nanoparticles with composition Ni(1-x)CoxFe2O4, where 0.0 ? x ? 1.0, are synthesized using co-precipitation method. The XRD spectra revealed the single phase spinel structure and the average sizes of nanoparticles are estimated to be 16-19 nm. These sizes are small enough to achieve the suitable signal to noise ratio in the high density recording media. The lattice parameter and coercivity shows monotonic increment with the increase of Co contents ascribed to the larger ionic radii of the cobalt ion. The specific saturation magnetization (Ms), remanent magnetization (Mr) and the coercivity (Hc) of the spinel ferrites are further improved by the substitutions of Co+2 ions. The values of Ms for NiFe2O4 and CoFe2O4 are found to be 43.92 and 78.59 emu/g, respectively and Hc are in the range of 51-778 Oe. The FTIR spectra of the spinel phase calcinated at 600 °C exhibit two prominent fundamental absorption bands in the range of 350-600 cm-1 assigned to the intrinsic stretching vibrations of the metal at the tetrahedral and octahedral sites. The role played by the Co ions in improving the structural and magnetic properties are analyzed and understood. Our simple, economic and environmental friendly preparation method may contribute towards the controlled growth of high quality ferrite nanopowders, potential candidates for recording.

Ati, Ali A.; Othaman, Zulkafli; Samavati, Alireza

2013-11-01

36

Magneto-optical waveguides made of cobalt ferrite nanoparticles embedded in silica\\/zirconia organic-inorganic matrix  

Microsoft Academic Search

This paper describes a way to develop magneto-optical waveguides via sol-gel process. They are made of cobalt ferrite nanoparticles embedded in a silica\\/zirconia matrix. Thin films are coated on glass substrate using the dip-coating technique. Annealing and UV treatment are applied to finalize sample preparation. Therefore, planar waveguides combining magneto-optical properties with a low refractive index (~1,5) are obtained. M-lines

Fadi Choueikani; François Royer; Damien Jamon; Ali Siblini; Jean Jacques Rousseau; Sophie Neveu; Jamal Charara

2009-01-01

37

Spindly cobalt ferrite nanocrystals: preparation, characterization and magnetic properties.  

PubMed

In this paper we describe the preparation of homogeneously needle-shaped cobalt ferrite (CoFe(2)O(4)) nanocrystals on a large scale through the smooth decomposition of urea and the resulting co-precipitation of Co(2+) and Fe(3+) in oleic acid micelles. Furthermore, we found that other ferrite nanocrystals with a needle-like shape, such as zinc ferrite (ZnFe(2)O(4)) and nickel ferrite (NiFe(2)O(4)), can be prepared by the same process. Needle-shaped CoFe(2)O(4) nanocrystals dispersed in an aqueous solution containing oleic acid exhibit excellent stability and the formed colloid does not produce any precipitations after two months, which is of prime importance if these materials are applied in magnetic fluids. X-ray diffraction (XRD) measurements were used to characterize the phase and component of the co-precipitation products, and demonstrate that they are spinel ferrite with a cubic symmetry. Transmission electron microscopy (TEM) observation showed that all the nanocrystals present a needle-like shape with a 22 nm short axis and an aspect ratio of around 6. Varying the concentration of oleic acid did not bring about any obvious influence on the size distribution and shapes of CoFe(2)O(4). The magnetic properties of the needle-shaped CoFe(2)O(4) nanocrystals were evaluated by using a vibrating sample magnetometer (VSM), electron paramagnetic resonance (EPR), and a Mössbauer spectrometer, and the results all demonstrated that CoFe(2)O(4) nanocrystals were superparamagnetic at room temperature. PMID:21727421

Cao, Xuebo; Gu, Li

2005-02-01

38

Magnetization anomalies of nanosize zinc ferrite particles prepared using electrodeposition  

Microsoft Academic Search

Nanosize zinc ferrite particles have been prepared for the first time using electrodeposition. Zinc and iron are deposited on the cathode from a common bath containing the salts of zinc and iron. The deposited materials were forced to undergo electrochemical oxidation in a strong alkaline solution (1M KOH) to convert them into oxides. Crystallization in ZnFe2O4 structure was obtained by

M. K. Roy; H. C. Verma

2006-01-01

39

Magnetization anomalies of nanosize zinc ferrite particles prepared using electrodeposition  

Microsoft Academic Search

Nanosize zinc ferrite particles have been prepared for the first time using electrodeposition. Zinc and iron are deposited on the cathode from a common bath containing the salts of zinc and iron. The deposited materials were forced to undergo electrochemical oxidation in a strong alkaline solution (1 M KOH) to convert them into oxides. Crystallization in ZnFe2O4 structure was obtained

M. K. Roy; H. C. Verma

2006-01-01

40

Microwave-hydrothermal synthesis of perovskite bismuth ferrite nanoparticles  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer BiFeO{sub 3} (BFO) nanoparticles were grown by hydrothermal microwave method (HTMW). Black-Right-Pointing-Pointer The soaking time is effective in improving phase formation. Black-Right-Pointing-Pointer Rietveld refinement reveals an orthorhombic structure. Black-Right-Pointing-Pointer The observed magnetism of the BFO crystallites is a consequence of particle size. Black-Right-Pointing-Pointer The HTMW is a genuine technique for low temperatures and short times of synthesis. -- Abstract: Hydrothermal microwave method (HTMW) was used to synthesize crystalline bismuth ferrite (BiFeO{sub 3}) nanoparticles (BFO) in the temperature of 180 Degree-Sign C with times ranging from 5 min to 1 h. BFO nanoparticles were characterized by means of X-ray analyses, FT-IR, Raman spectroscopy, TG-DTA and FE-SEM. X-ray diffraction results indicated that longer soaking time was benefit to refraining the formation of any impurity phases and growing BFO crystallites into almost single-phase perovskites. Typical FT-IR spectra for BFO nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH{sup -} groups, commonly found in materials obtained by HTMW process. Compared with the conventional solid-state reaction process, submicron BFO crystallites with better homogeneity could be produced at the temperature as low as 180 Degree-Sign C. These results show that the HTMW synthesis route is rapid, cost effective, and could be used as an alternative to obtain BFO nanoparticles in the temperature of 180 Degree-Sign C for 1 h.

Biasotto, G. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)] [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil); Simoes, A.Z., E-mail: alezipo@yahoo.com [Universidade Estadual Paulista-Unesp, Faculdade de Engenharia de Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Pedregulho, CEP 12516-410, Guaratingueta, SP (Brazil); Foschini, C.R.; Zaghete, M.A.; Varela, J.A.; Longo, E. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)] [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)

2011-12-15

41

Electromagnetic properties of NiZn ferrite nanoparticles and their polymer composites  

NASA Astrophysics Data System (ADS)

The magnetic properties of polycrystalline NiZn ferrite nanoparticles synthesized using a polyol-reduction and coprecipitation reaction methods have been investigated. The effects on magnetization of synthesis approach, chemical composition, processing conditions, and on the size of nanoparticles on magnetization have been investigated. The measured room-temperature magnetization for the as-prepared magnetic nanoparticles (MNP) synthesized via polyol-reduction and coprecipitation is 69 Am2 kg-1 and 14 Am2 kg-1, respectively. X-ray diffraction measurements confirm spinel structure of the particles with an estimated grain size of ˜80 nm obtained from the polyol-reduction and 28 nm obtained from these coprecipitation techniques. Upon calcination under atmospheric conditions at different temperatures between 800 °C and 1000 °C, the magnetization, M, of the coprecipitated MNP increases to 76 Am2 kg-1 with an estimated grain size of 90 nm. The MNP-polymer nanocomposites made from the synthesized MNP in various loading fraction and high density polyethylene exhibit interesting electromagnetic properties. The measured permeability and permittivity of the magnetic nanoparticle-polymer nanocomposites increases with the loading fractions of the magnetic nanoparticles, suggesting control for impedance matching for antenna applications.

Parsons, P.; Duncan, K.; Giri, A. K.; Xiao, J. Q.; Karna, S. P.

2014-05-01

42

Direct dyes removal using modified magnetic ferrite nanoparticle  

PubMed Central

The magnetic adsorbent nanoparticle was modified using cationic surface active agent. Zinc ferrite nanoparticle and cetyl trimethylammonium bromide were used as an adsorbent and a surface active agent, respectively. Dye removal ability of the surface modified nanoparticle as an adsorbent was investigated. Direct Green 6 (DG6), Direct Red 31 (DR31) and Direct Red 23 (DR23) were used. The characteristics of the adsorbent were studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of adsorbent dosage, initial dye concentration and salt was evaluated. In ternary system, dye removal of the adsorbent at 90, 120, 150 and 200 mg/L dye concentration was 63, 45, 30 and 23% for DR23, 97, 90, 78 and 45% for DR31 and 51, 48, 42 and 37% for DG6, respectively. It was found that dye adsorption onto the adsorbent followed Langmuir isotherm. The adsorption kinetic of dyes was found to conform to pseudo-second order kinetics. PMID:24991427

2014-01-01

43

Cellular Uptake and Biocompatibility of Bismuth Ferrite Harmonic Advanced Nanoparticles  

E-print Network

Bismuth Ferrite (BFO) nanoparticles (BFO-NP) display interesting optical (nonlinear response) and magnetic properties which make them amenable for bio-oriented applications as intra- and extra membrane contrast agents. Due to the relatively recent availability of this material in well dispersed nanometric form, its biocompatibility was not known to date. In this study, we present a thorough assessment of the effects of in vitro exposure of human adenocarcinoma (A549), lung squamous carcinoma (NCI-H520), and acute monocytic leukemia (THP-1) cell lines to uncoated and poly(ethylene glycol)-coated BFO-NP in the form of cytotoxicity, haemolytic response and biocompatibility. Our results support the attractiveness of the functional-BFO towards biomedical applications focused on advanced diagnostic imaging.

Staedler, Davide; Magouroux, Thibaud; Rogov, Andrii; Maguire, Ciaran Manus; Mohamed, Bashir M; Schwung, Sebastian; Rytz, Daniel; Jüstel, Thomas; Hwu, Stéphanie; Mugnier, Yannick; Dantec, Ronan Le; Volkov, Yuri; Gerber-Lemaire, Sandrine; Prina-Melloc, Adriele; Bonacina, Luigi; Wolf, Jean-Pierre

2014-01-01

44

Experimental studies of cobalt ferrite nanoparticles doped silica matrix 3D magneto-photonic crystals  

NASA Astrophysics Data System (ADS)

In this paper, we present the synthesis and the optical properties of 3D magneto-photonic structures. The elaboration process consists in firstly preparing then infiltrating polystyrene direct opals with a homogeneous solution of sol-gel silica precursors doped by cobalt ferrite nanoparticles, and finally dissolving the polystyrene spheres. Scanning Electron Microscopy (SEM) images of the prepared samples clearly evidence a periodic arrangement. Using a home-made polarimetric optical bench, the transmittance as a function of the wavelength, the Faraday rotation as a function of the applied magnetic field, and the Faraday ellipticity as a function of the wavelength and as a function of the applied magnetic field were measured. The existence of deep photonic band gaps (PBG), the unambiguous magnetic character of the samples and the qualitative modification of the Faraday ellipticity in the area of the PBG are evidenced.

Abou Diwan, E.; Royer, F.; Kekesi, R.; Jamon, D.; Blanc-Mignon, M. F.; Neveu, S.; Rousseau, J. J.

2013-05-01

45

Nanoparticles of Molybdenum Chlorophyllin Photosensitizer and Magnetic Citrate-Coated Cobalt Ferrite Complex Available to Hyperthermia and Photodynamic Therapy Clinical Trials  

Microsoft Academic Search

This study report on the synthesis and characterization of molybdenum chlorophyllin (Mo-Chl) compounds associated in a complex with magnetic nanoparticles (citrate-coated cobalt ferrite), the latter prepared as a biocompatible magnetic fluid (MF). The complex material was developed for application as a synergic drug for cancer treatment using Photodynamic Therapy (PDT) and Hyperthermia (HPT). Chlorophyllin was obtained from alkaline extraction of

Fernando L. Primo; Paloma L. A. G. Cordo; Alberto F. Neto; Paulo C. Morais; Antonio C. Tedesco

2010-01-01

46

Magnetic properties of cobalt-ferrite nanoparticles embedded in polystyrene resin  

SciTech Connect

Samples of maghemite and cobalt-ferrite nanoparticles (sizes, 3-10 nm) were prepared by cross-linking sulfonated polystyrene resin with aqueous solutions of (1) FeCl{sub 2}, (2) 80%FeCl{sub 2}+20%CoCl{sub 2}, (3) FeCl{sub 3}, and (4) 80%FeCl{sub 3}+20%CoCl{sub 2} by volume. Chemical analysis, x-ray powder-diffraction, and {sup 57}Fe Moessbauer spectroscopic measurements show that samples 1 and 3 consist of {gamma}-Fe{sub 2}O{sub 3} nanoparticles (sizes, {approx}10 and 3 nm) and sample 2 and 4 consist of Co{sub x}Fe{sub 3-x}O{sub 4} nanoparticles (sizes, {approx}10 and 4 nm). The temperature dependence of the zero-field-cooled and field-cooled magnetizations at low temperatures, together with a magnetic hysteresis in the M versus H data below blocking temperatures, demonstrate superparamagnetic behavior. The introduction of Co in the iron oxide-resin matrix results in an increase in the blocking temperature of nanoparticles.

Vaishnava, P. P.; Senaratne, U.; Buc, E.; Naik, R.; Naik, V. M.; Tsoi, G.; Wenger, L. E.; Boolchand, P. [Kettering University, Flint, Michigan 48504 (United States); Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201 (United States); University of Michigan-Dearborn, Dearborn, Michigan 48128 (United States); University of Alabama, Birmingham, Alabama 35294 (United States); Department of ECECS, University of Cincinnati, Ohio 45221 (United States)

2006-04-15

47

Microstructural and Mössbauer properties of low temperature synthesized Ni-Cd-Al ferrite nanoparticles  

PubMed Central

We report the influence of Al3+ doping on the microstructural and Mössbauer properties of ferrite nanoparticles of basic composition Ni0.2Cd0.3Fe2.5 - xAlxO4 (0.0 ? x ? 0.5) prepared through simple sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, transmission electron microscopy (TEM), Fourier transformation infrared (FTIR), and Mössbauer spectroscopy techniques were used to investigate the structural, chemical, and Mössbauer properties of the grown nanoparticles. XRD results confirm that all the samples are single-phase cubic spinel in structure excluding the presence of any secondary phase corresponding to any structure. SEM micrographs show the synthesized nanoparticles are agglomerated but spherical in shape. The average crystallite size of the grown nanoparticles was calculated through Scherrer formula and confirmed by TEM and was found between 2 and 8 nm (± 1). FTIR results show the presence of two vibrational bands corresponding to tetrahedral and octahedral sites. Mössbauer spectroscopy shows that all the samples exhibit superparamagnetism, and the quadrupole interaction increases with the substitution of Al3+ ions. PMID:21851597

2011-01-01

48

Infield Mossbauer study of disordered surface spins in core\\/shell ferrite nanoparticles  

Microsoft Academic Search

Magnetization and Mossbauer spectroscopy measurements are performed at low temperature under high field, on nanoparticles with a nickel ferrite core and a maghemite shell. These nanoparticles present finite size and surface effects, together with exchange anisotropy. High field magnetization brings the evidences of a monodomain ordered core and surface spins freezing in disorder at low temperature. Mossbauer spectra at 4.2

E. C. Sousa; H. R. Rechenberg; J. Depeyrot; J. A. Gomes; R. Aquino; F. A. Tourinho; V. Dupuis; R. Perzynski

2009-01-01

49

Synthesis and characterization of nickel ferrite magnetic nanoparticles by co-precipitation method  

NASA Astrophysics Data System (ADS)

Magnetic nickel ferrite (NiFe2O4) nanoparticles have been synthesized via co-precipitation method by varying the metal precursors ratio. Four different precursors ratio (Fe:Ni) are varied at 40:60, 50:50, 60:40 and 80:20. The size of the nanoparticles is found to increase with increasing iron (Fe) content. In addition, the morphology of the particles are observed to change from spherical to a shape similar to a nanooctahedral particle when the Fe content in the initial precursors ratio increases. The X-ray Diffraction (XRD) patterns have proved the presence of nickel ferrite nanoparticles. The magnetic properties characterized by Vibrating Sample Magnetometer (VSM) at room temperature proved that the assynthesized nickel ferrite nanoparticles are ferromagnetic and the saturation magnetization (Ms) increases with the content of Fe in the sample.

Ong, B. H.; Chee, E. S. C.; Abd Hamid, S. B. O. A.; Lim, K. P.

2012-11-01

50

The effect of starting materials and preparation process on the properties of magnesium ferrite pigment  

Microsoft Academic Search

Purpose – To prepare of fine particle size magnesium ferrite pigments by sol-gel method. Design\\/methodology\\/approach – Different magnesium ferrite pigments with stoichiometric ratios were prepared by sol-gel and dispersion methods. The characterisation of magnesium ferrite pigments were based on X-ray diffraction, transmission electron microscope, particle size distribution, thermal and magnetometric analyses. Findings – The type of polymer and the starting

F. F. Abdel-Mohsen; H. S. Emira

2005-01-01

51

Synthesis of nickel-zinc ferrite nanoparticles in polyol: morphological, structural and magnetic studies  

NASA Astrophysics Data System (ADS)

Nickel-zinc ferrite monodisperse nanoparticles are synthesized by forced hydrolysis in diethylenglycol. FC and ZFC susceptibility curves suggest that they present superparmagnetic behaviour with a blocking temperature between 63 and 15 K depending on the zinc content. The saturation magnetization of the nanocrystals at 5 K is very close to that of bulk materials, and very high compared to that of similar particles prepared by other chemical routes. High Resolution Transmission Electron Microscopy and In-field Mössbauer studies show clearly that these relatively high values are mainly due to: (i) the high crystalline quality of the particles and (ii) a cation distribution different from the classical distribution encountered in the bulk material.

Beji, Z.; Ben Chaabane, T.; Smiri, L. S.; Ammar, S.; Fiévet, F.; Jouini, N.; Grenèche, J. M.

2006-02-01

52

Evaluation of nickel ferrite nanoparticles coated with oleylamine by NMR relaxation measurements and magnetic hyperthermia.  

PubMed

Nickel ferrite nanoparticles were synthesized via a facile solvothermal approach. Oleylamine (OAm) was used in all synthetic procedures as a stabilizing agent and solvent. By varying the polarity of the solvents, hydrophobic NiFe2O4 nanoparticles coated with OAm of relatively similar sizes (9-11.7 nm) and in a range of magnetization values (32.0-53.5 emu g(-1)) were obtained. The as-prepared hydrophobic nanoparticles were characterized by XRD, TEM, SEM, TGA and VSM and converted to hydrophilic by two different approaches. The addition of a positively charged ligand (cetyltrimethyl ammonium bromide, CTAB) and the ligand exchange procedure (2,3-dimercaptosuccinic acid, DMSA) have been successfully applied. The aqueous suspensions of NiFe2O4@CTAB and NiFe2O4@DMSA showed good colloidal stability after a long period of time. The different surface modification affected both the NMR relaxometric measurements and the hyperthermia effects. In both techniques CTAB modification demonstrated higher r2 relaxivity (278.9 s(-1) mM(-1) in an NMR spectrometer at 11.7 T) and SAR values (423.4 W g(-1) at an applied AC field with a particle concentration of 0.5 mg mL(-1)). The results indicate that a coating with a larger molecule as CTAB under the same size, shape and magnetization of NiFe2O4 NPs gave rise to NMR relaxometric properties and heating efficacy. PMID:24413465

Menelaou, M; Georgoula, K; Simeonidis, K; Dendrinou-Samara, C

2014-03-01

53

Preparation of transparent conductors ferroelectric memory materials and ferrites  

SciTech Connect

A process for the preparation by electrodeposition of metal oxide film and powder compounds for ferroelectric memory materials and ferrites wherein the metal oxide includes a plurality of metals. The process comprises providing an electrodeposition bath, providing soluble salts of the metals to this bath, electrically energizing the bath to thereby cause formation of a recoverable film of metal on the electrode, recovering the resultant film as a film or a powder, and recovering powder formed on the floor of the bath. The films and powders so produced are subsequently annealed to thereby produce metal oxide for use in electronic applications. The process can be employed to produce metal-doped metal oxide film and powder compounds for transparent conductors. The process for preparation of these metal-doped metal oxides follows that described above.

Bhattacharya, Raghu Nath (Littleton, CO); Ginley, David S. (Evergreen, CO)

1998-01-01

54

Iron-based soft magnetic composites with MnZn ferrite nanoparticles coating obtained by solgel method  

E-print Network

Iron-based soft magnetic composites with Mn­Zn ferrite nanoparticles coating obtained by sol focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn­Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm

Volinsky, Alex A.

55

Structural and magnetic properties correlated with cation distribution of Mo-substituted cobalt ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Mo-substituted cobalt ferrite nanoparticles; CoFe2-2xMoxO4 (0.0?x?0.3) were prepared by a one-step solution combustion synthesis technique. The reactants were metal nitrates and glycine as a fuel. The samples were characterized using an X-ray diffraction (XRD), a transmission electron microscope (TEM) and a vibrating sample magnetometer (VSM). XRD analysis revealed a pure single phase of cubic spinel ferrites for all samples with x up to 0.3. The lattice parameter decreases with Mo6+ substitution linearly up to x=0.15, then nonlinearly for x?0.2. Rietveld analysis and saturation magnetization (Ms) revealed that Mo6+ replaced Fe3+ in the tetrahedral A-sites up to x=0.15, then it replaced Fe3+ in both A-sites and B-sites for x?0.2. The saturation magnetization (Ms) increases with increasing Mo6+ substitution up to x=0.15 then decreases. The crystallite size decreased while the microstrain increased with increasing Mo6+ substitution. Inserting Mo6+ produces large residents of defects and cation vacancies.

Heiba, Z. K.; Mostafa, Nasser Y.; Abd-Elkader, Omar H.

2014-11-01

56

Spin-flop transition, magnetic and microwave absorption properties of ?-Fe2O4 spinel type ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

We have prepared NiFe2O4, CoFe2O4, Ni0.6Zn0.4Fe2O4 and ZnFe2O4 spinel type ferrite nanoparticles by surfactant-assisted hydrothermal process using cetyltrimethylammonium bromide (CTAB). The spin-flop transition, magnetic, dielectric and permittivity characterizations have been investigated. The spin-flop transition occurs from antiferromagnetic state to mixed state and then ferromagnetic state for Zn doped samples. The spin-flop transition occurs in the temperature range of 50-250 K. The ionic conduction, dipolar relaxation, atomic polarization and electronic polarization are the main mechanisms that contribute to the permittivity of a dielectric material. The permittivity increases with increasing frequency. This suggests a resonance behavior, which is expected when the ferrite samples are highly conductive and skin effect become significant. These samples will provide great benefits for electromagnetic applications and electromagnetic interference shielding characteristics.

Yalç?n, Orhan; Bayrakdar, Harun; Özüm, Songül

2013-10-01

57

Mn-Zn Ferrite Powder Preparation by Hydrothermal Process from Used Dry Batteries  

NASA Astrophysics Data System (ADS)

In this study, we propose a new process to synthesize Mn-Zn ferrite, using oxides of manganese and zinc extracted from used dry batteries, and ferrous chloride waste solution from iron plants or electronic plants recycled as starting raw materials. It is found that Mn-Zn ferrite powder prepared by the hydrothermal process from used dry batteries revealed the formation of cubic ferrite with a saturation magnetization (MS) of 58.8 emu/g.

Liu, Chung?Wen; Lin, Cheng?Hsiung; Fu, Yen?Pei

2006-05-01

58

Magnetic properties of Co-ferrite-doped hydroxyapatite nanoparticles having a core\\/shell structure  

Microsoft Academic Search

The magnetic properties of Co-ferrite-doped hydroxyapatite (HAP) nanoparticles of composition Ca10?3xFe2xCox(PO4)6(OH)2 (where x=0, 0.1, 0.2, 0.3, 0.4 and 0.5% mole) are studied. Transmission electron microscope micrograms show that the 90nm size nanoparticles annealed at 1250°C have a core\\/shell structure. Their electron diffraction patterns show that the shell is composed of the hydroxyapatite and the core is composed of the Co-ferrite,

N. Petchsang; W. Pon-On; J. H. Hodak; I. M. Tang

2009-01-01

59

Synthesis of core/shell spinel ferrite/carbon nanoparticles with enhanced cycling stability for lithium ion battery anodes  

NASA Astrophysics Data System (ADS)

Monodispersed core/shell spinel ferrite/carbon nanoparticles are formed by thermolysis of metal (Fe3+, Co2+) oleates followed by carbon coating. The phase and morphology of nanoparticles are characterized by x-ray diffraction and transmission electron microscopy. Pure Fe3O4 and CoFe2O4 nanoparticles are initially prepared through thermal decomposition of metal-oleate precursors at 310?°C and they are found to exhibit poor electrochemical performance because of the easy aggregation of nanoparticles and the resulting increase in the interparticle contact resistance. In contrast, uniform carbon coating of Fe3O4 and CoFe2O4 nanoparticles by low-temperature (180?°C) decomposition of malic acid allowed each nanoparticle to be electrically wired to a current collector through a conducting percolative path. Core/shell Fe3O4/C and CoFe2O4/C nanocomposite electrodes show a high specific capacity that can exceed 700 mAh g-1 after 200 cycles, along with enhanced cycling stability.

Jin, Yun-Ho; Seo, Seung-Deok; Shim, Hyun-Woo; Park, Kyung-Soo; Kim, Dong-Wan

2012-03-01

60

Magnetic, dielectric and sensing properties of manganese substituted copper ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese substituted copper ferrite nanoparticles were synthesized by an auto-combustion technique using metal nitrates and urea for gas sensor application. The products were characterized by XRD, SEM, EDX, TEM and VSM techniques. The effect of annealing temperature on the particle size, magnetic and dielectric properties of Mn-Cu ferrite nanoparticles was analyzed. The size of the particles are in the range of ~9-45 nm. The effect of annealing on the magnetic properties is discussed with the help of variation in saturation magnetization (Ms) and coercivity (Hc) by vibrating sample magnetometer (VSM). The dielectric loss and dielectric constant have been measured in the frequency range of 100 kHz-5 MHz. Furthermore, Conductance response of Mn-Cu ferrite nanomaterial was measured by exposing the material to reducing gas like liquefied petroleum gas (LPG).

Kumar, E. Ranjith; Jayaprakash, R.; Devi, G. Sarala; Reddy, P. Siva Prasada

2014-04-01

61

Copper ferrite nanoparticle-mediated N-arylation of heterocycles: a ligand-free reaction  

Microsoft Academic Search

The synergistic effects of iron and copper in copper ferrite nanoparticles for the N-arylation of heterocycles with aryl halides were demonstrated. The magnetic nature of the catalyst facilitates its removal from the reaction medium for further use. Negligible leaching of Cu and Fe in consecutive cycles makes the catalyst economical and environmentally benign for C–N cross-coupling reactions.

Niranjan Panda; Ashis Kumar Jena; Sasmita Mohapatra; Smruti Ranjan Rout

2011-01-01

62

Assessment of cytotoxicity and oxidative effect of Bismuth Ferrite (BFO) harmonic nanoparticles for localized DNA photo-interaction  

NASA Astrophysics Data System (ADS)

Bismuth Ferrite nanoparticles have been recently used to selectively interact with malignant cell DNA via in situ generated second harmonic in a novel theranostics protocol [Nanoscale 6(5), pp. 2929, 2014]. In this report, we extend the screening of biocompatibility of BFO uncoated uncoated nanoparticles and assess the nanoparticle- mediated production of reactive oxygen species as a function of excitation wavelength.

Staedler, Davide; Magouroux, Thibaud; Passemard, Solène; Ciepielewski, Daniel; Gerber-Lemaire, Sandrine; Wolf, Jean-Pierre; Bonacina, Luigi

2014-09-01

63

Structure of Oxide Nanoparticles in Fe-16Cr MA/ODS Ferritic Steel  

SciTech Connect

Oxide nanoparticles in Fe-16Cr ODS ferritic steel fabricated by mechanical alloying (MA) method have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. A partial crystallization of oxide nanoparticles was frequently observed in as-fabricated ODS steel. The crystal structure of crystalline oxide particles is identified to be mainly Y{sub 4}Al{sub 2}O{sub 9} (YAM) with a monoclinic structure. Large nanoparticles with a diameter larger than 20 nm tend to be incoherent and have a nearly spherical shape, whereas small nanoparticles with a diameter smaller than 10 nm tend to be coherent or semi-coherent and have faceted boundaries. The oxide nanoparticles become fully crystallized after prolonged annealing at 900 C. These results lead us to propose a three-stage formation mechanism of oxide nanoparticles in MA/ODS steels.

Hsiung, L; Fluss, M; Kimura, A

2010-04-06

64

Maximizing hysteretic losses in magnetic ferrite nanoparticles via model-driven synthesis and materials optimization.  

PubMed

This article develops a set of design guidelines for maximizing heat dissipation characteristics of magnetic ferrite MFe2O4 (M = Mn, Fe, Co) nanoparticles in alternating magnetic fields. Using magnetic and structural nanoparticle characterization, we identify key synthetic parameters in the thermal decomposition of organometallic precursors that yield optimized magnetic nanoparticles over a wide range of sizes and compositions. The developed synthetic procedures allow for gram-scale production of magnetic nanoparticles stable in physiological buffer for several months. Our magnetic nanoparticles display some of the highest heat dissipation rates, which are in qualitative agreement with the trends predicted by a dynamic hysteresis model of coherent magnetization reversal in single domain magnetic particles. By combining physical simulations with robust scalable synthesis and materials characterization techniques, this work provides a pathway to a model-driven design of magnetic nanoparticles tailored to a variety of biomedical applications ranging from cancer hyperthermia to remote control of gene expression. PMID:24016039

Chen, Ritchie; Christiansen, Michael G; Anikeeva, Polina

2013-10-22

65

Magnetic properties of bio-synthesized zinc ferrite nanoparticles  

SciTech Connect

The magnetic properties of zinc ferrite (Zn-substituted magnetite, Zn{sub y}Fe{sub 1-y}Fe{sub 2}O{sub 4}) formed by a microbial process compared favorably with chemically synthesized materials. A metal reducing bacterium, Thermoanaerobacter, strain TOR-39 was incubated with Zn{sub x}Fe{sub 1-x}OOH (x=0.01, 0.1, and 0.15) precursors and produced nanoparticulate zinc ferrites. Composition and crystalline structure of the resulting zinc ferrites were verified using X-ray fluorescence, X-ray diffraction, transmission electron microscopy, and neutron diffraction. The average composition from triplicates gave a value for y of 0.02, 0.23, and 0.30 with the greatest standard deviation of 0.02. Average crystallite sizes were determined to be 67, 49, and 25 nm, respectively. While crystallite size decreased with more Zn substitution, the lattice parameter and the unit cell volume showed a gradual increase in agreement with previous literature values. The magnetic properties were characterized using a superconducting quantum interference device magnetometer and were compared with values for the saturation magnetization (M{sub s}) reported in the literature. The averaged M{sub s} values for the triplicates with the largest amount of zinc (y=0.30) gave values of 100.1, 96.5, and 69.7 emu/g at temperatures of 5, 80, and 300 K, respectively indicating increased magnetic properties of the bacterially synthesized zinc ferrites.

Yeary, Lucas W [ORNL; Moon, Ji Won [ORNL; Rawn, Claudia J [ORNL; Love, Lonnie J [ORNL; Rondinone, Adam Justin [ORNL; Thompson, James R [ORNL; Chakoumakos, Bryan C [ORNL; Phelps, Tommy Joe [ORNL

2011-01-01

66

Preparation of DPPE-Stabilized Gold Nanoparticles  

ERIC Educational Resources Information Center

An experiment is presented that introduces students to nanotechnology through the preparation of nanoparticles and their visualization using transmission electron microscopy (TEM). The experiment familiarizes the students with nonaqueous solvents, biphasic reactions, phase-transfer agents, ligands to stabilize growing nanoparticles, and bidentate…

Dungey, Keenan E.; Muller, David P.; Gunter, Tammy

2005-01-01

67

Silicon nanoparticles: Preparation, properties, and applications  

NASA Astrophysics Data System (ADS)

Silicon nanoparticles have attracted great attention in the past decades because of their intriguing physical properties, active surface state, distinctive photoluminescence and biocompatibility. In this review, we present some of the recent progress in preparation methodologies and surface functionalization approaches of silicon nanoparticles. Further, their promising applications in the fields of energy and electronic engineering are introduced.

Chang, Huan; Sun, Shu-Qing

2014-08-01

68

Manifestation of weak ferromagnetism and photocatalytic activity in bismuth ferrite nanoparticles  

SciTech Connect

Bismuth ferrite (BFO) nanoparticles were synthesized by auto-ignition technique with and without adding ignition fuel such as citric acid. The presence of citric acid in the reaction mixture yielded highly-magnetic BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite. When this composite was annealed to 650 Degree-Sign C, a single phase BFO was formed with average crystallite size of 50 nm and showed weak ferromagnetic behavior. Conversely, the phase pure BFO prepared without adding citric acid exhibited antiferromagnetism because of its larger crystallite size of around 70 nm. The visible-light driven photocatalytic activity of both the pure BFO and BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite were examined by degrading methyl orange dye. The pure BFO showed a moderate photocatalytic activity; while BFO/{gamma}-Fe{sub 2}O{sub 3} nanocomposite showed enhanced activity. This could be probably due to the optimal band gap ratio between BFO and {gamma}-Fe{sub 2}O{sub 3} phases reduced the recombination of electron-hole pairs which aided in the enhancement of photocatalytic activity.

Sakar, M.; Balakumar, S. [National Center for Nanoscience and Nanotechnology, University of Madras, Chennai - 600025 (India); Saravanan, P. [Advanced Magnetics Group, Defence Metallurgical Research Laboratory, Hyderabad - 500 058 (India); Jaisankar, S. N. [Polymer Lab, Central Leather Research Laboratory, Adyar, Chennai - 600020 (India)

2013-02-05

69

Manifestation of weak ferromagnetism and photocatalytic activity in bismuth ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Bismuth ferrite (BFO) nanoparticles were synthesized by auto-ignition technique with and without adding ignition fuel such as citric acid. The presence of citric acid in the reaction mixture yielded highly-magnetic BFO/?-Fe2O3 nanocomposite. When this composite was annealed to 650°C, a single phase BFO was formed with average crystallite size of 50 nm and showed weak ferromagnetic behavior. Conversely, the phase pure BFO prepared without adding citric acid exhibited antiferromagnetism because of its larger crystallite size of around 70 nm. The visible-light driven photocatalytic activity of both the pure BFO and BFO/?-Fe2O3 nanocomposite were examined by degrading methyl orange dye. The pure BFO showed a moderate photocatalytic activity; while BFO/?-Fe2O3 nanocomposite showed enhanced activity. This could be probably due to the optimal band gap ratio between BFO and ?-Fe2O3 phases reduced the recombination of electron-hole pairs which aided in the enhancement of photocatalytic activity.

Sakar, M.; Balakumar, S.; Saravanan, P.; Jaisankar, S. N.

2013-02-01

70

Study Of Structural And Dielectric Properties Of Ni-Mg Ferrite Nanoparticles  

SciTech Connect

Ferrite nanoparticles of basic composition Ni{sub 0.7}Mg{sub 0.3}Fe{sub 2-x}Al{sub x}O{sub 4}(0.0{<=}x{<=}0.5) were prepared through citrate gel method and characterized using XRD, TEM and dielectric spectroscopy techniques. The dielectric properties were studied as a function of frequency (42 Hz-5 MHz) at room temperature. The average particle size has been found between 8-17 nm. The dispersion in dielectric properties and ac conductivity ({sigma}{sub ac}), with frequency reveals that the dispersion is due to Maxwell-Wagner type of interfacial polarization in general and the hopping of charge between Fe{sup 2+} and Fe{sup 3+} as well as between Ni{sup 2+} and Ni{sup 3+} ions at B-sites. The dielectric loss tangent (tan {delta}) shows abnormal behavior for the compositions 0.3, 0.4 and 0.5 which has been explained in the light of Rezlescue model.

Nongjai, Razia; Batoo, Khalid Mujasam; Khan, Shakeel [Dept. of Applied Physics, Aligarh Muslim University, Aligarh, 202002 (India) and King Abdullah Institute for Nanotechnology, King Saud University, Riyadh, 11451 (Saudi Arabia)

2010-12-01

71

Preparation of core shell particles consisting of cobalt ferrite and silica by sol–gel process  

Microsoft Academic Search

Core shell particles consisting of a magnetic core of cobalt ferrite (CoFe2O4) and a shell of silica (SiO2) are prepared by sol–gel process using tetraethylorthosilicate (TEOS) as a precursor of silica, and metallic nitrates as precursors of ferrite. The core shell structure is confirmed by TEM. The magnetic properties of these nanocomposites are measured by PPMS in low temperature and

Shuping Zhang; Dawei Dong; Yu Sui; Zhiguo Liu; Hongxia Wang; Zhengnan Qian; Wenhui Su

2006-01-01

72

The anti-microbial activity of titania-nickel ferrite composite nanoparticles  

Microsoft Academic Search

A novel approach to synthesize a new generation of composite nanoparticles consisting of a photocatalytic shell of anatase-titania\\u000a and a magnetic core of nickel ferrite has been adopted combining reverse micelle and chemical hydrolysis techniques. Titania\\u000a is an effective anti-microbial agent that can be directly sprayed on infected areas of the human body or environment. Unfortunately,\\u000a titania is an electrical

S. Rana; R. D. K. Misra

2005-01-01

73

Magnetic properties of Co-ferrite-doped hydroxyapatite nanoparticles having a core\\/shell structure  

Microsoft Academic Search

The magnetic properties of Co-ferrite-doped hydroxyapatite (HAP) nanoparticles of composition Ca10-3xFe2xCox(PO4)6(OH)2 (where x=0, 0.1, 0.2, 0.3, 0.4 and 0.5% mole) are studied. Transmission electron microscope micrograms show that the 90 nm size nanoparticles annealed at 1250 °C have a core\\/shell structure. Their electron diffraction patterns show that the shell is composed of the hydroxyapatite and the core is composed of

N. Petchsang; W. Pon-On; J. H. Hodak; I. M. Tang

2009-01-01

74

Morphology of cobalt ferrite nanoparticle-polyelectrolyte multilayered nanocomposites  

NASA Astrophysics Data System (ADS)

Novel magnetic nanocomposite films with controlled morphology were produced via the electrostatic layer-by-layer assembly of cationic CoFe 2O 4 nanoparticles and anionic poly(3,4-ethylenedioxy thiophene)/poly(styrene sulfonic acid) (PEDOT:PSS) complex. The electrostatic interaction between nanoparticle and the polyelectrolyte complex ensured a stepwise growth of the nanocomposite film with virtually identical amounts of materials being adsorbed at each deposition cycle as observed by UV-vis spectroscopy. AFM images acquired under the tapping mode revealed a globular morphology with dense and continuous layers of nanoparticles with voids being filled with polymeric material.

Alcantara, G. B.; Paterno, L. G.; Fonseca, F. J.; Morais, P. C.; Soler, M. A. G.

2011-05-01

75

Bacterially synthesized ferrite nanoparticles for magnetic hyperthermia applications.  

PubMed

Magnetic hyperthermia uses AC stimulation of magnetic nanoparticles to generate heat for cancer cell destruction. Whilst nanoparticles produced inside magnetotactic bacteria have shown amongst the highest reported heating to date, these particles are magnetically blocked so that strong heating occurs only for mobile particles, unless magnetic field parameters are far outside clinical limits. Here, nanoparticles extracellularly produced by the bacteria Geobacter sulfurreducens are investigated that contain Co or Zn dopants to tune the magnetic anisotropy, saturation magnetization and nanoparticle sizes, enabling heating within clinical field constraints. The heating mechanisms specific to either Co or Zn doping are determined from frequency dependent specific absorption rate (SAR) measurements and innovative AC susceptometry simulations that use a realistic model concerning clusters of polydisperse nanoparticles in suspension. Whilst both particle types undergo magnetization relaxation and show heating effects in water under low AC frequency and field, only Zn doped particles maintain relaxation combined with hysteresis losses even when immobilized. This magnetic heating process could prove important in the biological environment where nanoparticle mobility may not be possible. Obtained SARs are discussed regarding clinical conditions which, together with their enhanced MRI contrast, indicate that biogenic Zn doped particles are promising for combined diagnostics and cancer therapy. PMID:25232657

Céspedes, Eva; Byrne, James M; Farrow, Neil; Moise, Sandhya; Coker, Victoria S; Bencsik, Martin; Lloyd, Jonathan R; Telling, Neil D

2014-10-01

76

Influence of the morphology of ferrite nanoparticles on the directed assembly into magnetically anisotropic hierarchical structures.  

PubMed

The effect of the morphology of ferrite nanoparticles on their assembly in a magnetic field was studied. Thin BaFe12O19 nanoplatelets were compared with isotropic, spherical or octahedral, CoFe2O4 nanoparticles, all of which were synthesized hydrothermally. The nanoplatelets and nanoparticles assembled into a variety of hierarchical structures from stable suspensions during the "drop deposition" and drying in a magnetic field. The alignment of the nanoparticles in the magnetic field was observed in situ with an optical microscope. The morphologies of the nanoparticles and the subsequent assemblies were observed with transmission and scanning electron microscopes, respectively. The magnetic properties of the nanoparticles and the assemblies were measured with a vibrating-sample magnetometer. The BaFe12O19 nanoplatelets aligned in the plane of the substrate and formed several-micrometers-thick, ordered films with a magnetic alignment of approximately 90%. The CoFe2O4 nanoparticles assembled into thick, dense columns with a height of several hundreds of micrometers and showed a magnetic alignment of up to 60%. The differences in the morphologies and the magnetic alignments between the BaFe12O19 and CoFe2O4 hierarchical structures could be explained in terms of the differences in the shape and magnetocrystalline structure of the specific nanoparticles. PMID:24841592

Lisjak, Darja; Jenuš, Petra; Mertelj, Alenka

2014-06-10

77

Bacterially synthesized ferrite nanoparticles for magnetic hyperthermia applications  

NASA Astrophysics Data System (ADS)

Magnetic hyperthermia uses AC stimulation of magnetic nanoparticles to generate heat for cancer cell destruction. Whilst nanoparticles produced inside magnetotactic bacteria have shown amongst the highest reported heating to date, these particles are magnetically blocked so that strong heating occurs only for mobile particles, unless magnetic field parameters are far outside clinical limits. Here, nanoparticles extracellularly produced by the bacteria Geobacter sulfurreducens are investigated that contain Co or Zn dopants to tune the magnetic anisotropy, saturation magnetization and nanoparticle sizes, enabling heating within clinical field constraints. The heating mechanisms specific to either Co or Zn doping are determined from frequency dependent specific absorption rate (SAR) measurements and innovative AC susceptometry simulations that use a realistic model concerning clusters of polydisperse nanoparticles in suspension. Whilst both particle types undergo magnetization relaxation and show heating effects in water under low AC frequency and field, only Zn doped particles maintain relaxation combined with hysteresis losses even when immobilized. This magnetic heating process could prove important in the biological environment where nanoparticle mobility may not be possible. Obtained SARs are discussed regarding clinical conditions which, together with their enhanced MRI contrast, indicate that biogenic Zn doped particles are promising for combined diagnostics and cancer therapy.Magnetic hyperthermia uses AC stimulation of magnetic nanoparticles to generate heat for cancer cell destruction. Whilst nanoparticles produced inside magnetotactic bacteria have shown amongst the highest reported heating to date, these particles are magnetically blocked so that strong heating occurs only for mobile particles, unless magnetic field parameters are far outside clinical limits. Here, nanoparticles extracellularly produced by the bacteria Geobacter sulfurreducens are investigated that contain Co or Zn dopants to tune the magnetic anisotropy, saturation magnetization and nanoparticle sizes, enabling heating within clinical field constraints. The heating mechanisms specific to either Co or Zn doping are determined from frequency dependent specific absorption rate (SAR) measurements and innovative AC susceptometry simulations that use a realistic model concerning clusters of polydisperse nanoparticles in suspension. Whilst both particle types undergo magnetization relaxation and show heating effects in water under low AC frequency and field, only Zn doped particles maintain relaxation combined with hysteresis losses even when immobilized. This magnetic heating process could prove important in the biological environment where nanoparticle mobility may not be possible. Obtained SARs are discussed regarding clinical conditions which, together with their enhanced MRI contrast, indicate that biogenic Zn doped particles are promising for combined diagnostics and cancer therapy. Electronic supplementary information (ESI) available: Further details of the cluster model of polydisperse nanoparticles used for the AC susceptibility simulations (Fig. S1 to S3). Examples of the heating curves and the linear fit used to determine the SAR values are shown in Fig. S4. Fig. S5 exhibits the energy loss per mass of iron during magnetic hyperthermia (from SAR values) normalized to H2 and frequency for further comparison among samples. Fig. S6 shows the comparison between the simulations of AC susceptibility spectra including regions below and above the experimental frequency range for MNA, Zn0.2 and Zn0.4 nanoparticles suspended in solvents with different viscosities (water, glycerol and a hypothetical high viscous solvent). Fig. S7 exhibits a comparison among the simulated ?'' susceptibility of MNA, Zn0.2 and Zn0.4 nanoparticles (a) in water and (b) in glycerol. See DOI: 10.1039/c4nr03004d

Céspedes, Eva; Byrne, James M.; Farrow, Neil; Moise, Sandhya; Coker, Victoria S.; Bencsik, Martin; Lloyd, Jonathan R.; Telling, Neil D.

2014-10-01

78

Conductivity of silver paste prepared from nanoparticles  

Microsoft Academic Search

Conductivity of silver pastes using nanoparticles was investigated with sintering temperatures. Nano-sized silver particles with 50–100nm in size were prepared by chemical reduction method. Silver pastes composed of nanoparticles (80wt%), Pb-free frit (1.0wt%) and organic vehicle (19wt%) were screen printed on alumina substrates and sintered at temperatures ranging from 250 to 450°C. As increasing the sintering temperatures, densification and grain

Dongseok Seo; Jongkook Lee

2008-01-01

79

Preparation of polythiophene coated gold nanoparticles  

Microsoft Academic Search

Gold core–polythiophene shell composite nanoparticles with a diameter of 6–8 nm have been prepared via a two-step process. The morphology and structures of the obtained nanocomposites were characterized by transmission electron microscopy, infrared and Raman spectroscopies. The nanoparticles can be stably dispersed in usual organic solvents such as ethanol. Thus, they can be easily processed and have potential applications in

Zhipan Zhang; Fan Wang; Feng'en Chen; Gaoquan Shi

2006-01-01

80

Method to prepare nanoparticles on porous mediums  

DOEpatents

A method to prepare porous medium decorated with nanoparticles involves contacting a suspension of nanoparticles in an ionic liquid with a porous medium such that the particles diffuse into the pores of the medium followed by heating the resulting composition to a temperature equal to or greater than the thermal decomposition temperature of the ionic liquid resulting in the removal of the liquid portion of the suspension. The nanoparticles can be a metal, an alloy, or a metal compound. The resulting compositions can be used as catalysts, sensors, or separators.

Vieth, Gabriel M. (Knoxville, TN) [Knoxville, TN; Dudney, Nancy J. (Oak Ridge, TN) [Oak Ridge, TN; Dai, Sheng (Knoxville, TN) [Knoxville, TN

2010-08-10

81

In-field Mossbauer study of disordered surface spins in core/shell ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetization and Mossbauer spectroscopy measurements are performed at low temperature under high field, on nanoparticles with a nickel ferrite core and a maghemite shell. These nanoparticles present finite size and surface effects, together with exchange anisotropy. High field magnetization brings the evidences of a monodomain ordered core and surface spins freezing in disorder at low temperature. Mossbauer spectra at 4.2 K present an extra contribution from the disordered surface which is field dependent. Field and size dependences of this latter show a progressive spin alignment along the ferrite core which is size dependent. The weak surface pinning condition of the nanoparticles confirms that the spin disorder is localized in the external shell. The underfield decrease in the mean canting angle in the superficial shell is then directly related to the unidirectional exchange anisotropy through the interface between the ordered core and the disordered shell. The obtained anisotropy field HEa scales as the inverse of the nanoparticle diameter, validating its interfacial origin. The associated anisotropy constant KEa equals 2.5×10-4 J/m2.

Sousa, E. C.; Rechenberg, H. R.; Depeyrot, J.; Gomes, J. A.; Aquino, R.; Tourinho, F. A.; Dupuis, V.; Perzynski, R.

2009-11-01

82

Structural, magnetic, dielectric and optical properties of nickel ferrite nanoparticles synthesized by co-precipitation method  

NASA Astrophysics Data System (ADS)

Nickel ferrite nanoparticles were synthesized by wet chemical co-precipitation method and the corresponding temperature dependent structural, magnetic and optical properties of these nanoparticles have been investigated. X-ray diffraction patterns show the single phase cubic spinal crystal structure belonging to the space group Fd3m. The average crystallite size varies in the range 8-20 nm with varying sintering temperature. Raman spectroscopy exhibits a doublet-like peak behaviour which indicates the presence of mixed spinel structure. The saturation magnetization, coercivity and remanence increase with increasing sintering temperature from 250 to 550 °C. The non-saturation and low values of magnetization at high fields indicate the strong surface effects to magnetization in NiFe2O4 nanoparticles. The g-value calculated from electron spin resonance spectrum indicates the transfer of divalent metallic ion from octahedral to tetrahedral site (i.e. mixed spinel structure). The dielectric permittivity, loss tangent and ac conductivity measurements show strong temperature dependence at all frequencies. The observed ac conductivity response suggests that the conduction in ferrite nanoparticles is due to feeble polaron hopping between Fe3+/Fe2+ ions. Room temperature UV-vis diffuse spectra indicate that NiFe2O4 is an indirect band gap material with band gap ranges from 1.27 to 1.47 eV with varying sintering temperature. The photoluminescence study clearly indicates that the Ni2+ ions occupy both octahedral and tetrahedral sites confirming mixed spinel structure.

Joshi, Seema; Kumar, Manoj; Chhoker, Sandeep; Srivastava, Geetika; Jewariya, Mukesh; Singh, V. N.

2014-11-01

83

Preparation of nanophase M-type ferrite and its laser-attenuated characteristics  

NASA Astrophysics Data System (ADS)

By citrate sol-gel auto-combustion method, the nanophase M-type planar hexagonal ferrite is prepared. The transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermal analysis are used to study the grain size, phase composition, microstructure and crystallization process. The results show that the nanophase M-type Sr-ferrite prepared by this method is single, and its grain size is smaller than 100 nm. Moreover, most of the grains present hexagonal sheet shape. Tests are carried out for its attenuation to 1.06 ?m laser. It is found that the extinction capability of the nanophase M-type Sr-ferrite smoke is good, and its mass extinction coefficient is 1.628 m2/g.

Liu, Xiang-Cui; Cheng, Xiang; Zhang, Liang; Liu, Jian-Hui; Du, Gui-Ping

2011-07-01

84

Biocompatible mesoporous silica-coated superparamagnetic manganese ferrite nanoparticles for targeted drug delivery and MR imaging applications.  

PubMed

Multifunctional mesoporous silica-coated superparamagnetic manganese ferrite (MnFe2O4) nanoparticles (M-MSN) were synthesized and evaluated for targeted drug delivery and magnetic resonance imaging (MRI) applications. MnFe2O4 nanoparticles were prepared by solvothermal route and were silica-coated by surface silylation using sol-gel reactions. Subsequently, silylation was done using (3-aminopropyl)triethoxysilane in presence of a surfactant (CTAB), followed by selective etching of the surfactant molecules that resulted in amine-functionalized superparamagnetic nanoparticles (NH2-MSN). Further modification of the surface of the NH2-MSN with targeting (folate) or fluorescent (RITC) molecules resulted in M-MSN. The formation of the M-MSN was proved by several characterization techniques viz. XRD, XPS, HRTEM, FESEM, VSM, BET surface area measurement, FTIR, and UV-Vis spectroscopy. The M-MSN were loaded with anticancer drug Doxorubicin and the efficacy of the DOX loaded M-MSN was evaluated through in vitro cytotoxicity, fluorescence microscopy, and apoptosis studies. The in vivo biocompatibility of the M-MSN was demonstrated in a mice-model system. Moreover, the M-MSN also acted as superior MRI contrast agent owing to a high magnetization value as well as superparamagnetic behavior at room temperature. These folate-conjugated nanoparticles (FA-MSN) exhibited stronger T2-weighted MRI contrast towards HeLa cells as compared to the nanoparticles without folate conjugation, justifying their potential importance in MRI based diagnosis of cancer. Such M-MSN with a magnetic core required for MRI imaging, a porous shell for carrying drug molecules, a targeting moeity for cancer cell specificity and a fluorescent molecule for imaging, all integrated into a single system, may potentially serve as an excellent material in biomedical applications. PMID:24980623

Sahoo, Banalata; Devi, K Sanjana P; Dutta, Sujan; Maiti, Tapas K; Pramanik, Panchanan; Dhara, Dibakar

2014-10-01

85

HRTEM Study of Oxide Nanoparticles in K3-ODS Ferritic Steel Developed for Radiation Tolerance  

SciTech Connect

Crystal and interfacial structures of oxide nanoparticles and radiation damage in 16Cr-4.5Al-0.3Ti-2W-0.37 Y{sub 2}O{sub 3} ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y{sub 4}Al{sub 2}O{sub 9} (YAM) oxide compound. Orientation relationships between the oxide and the matrix are found to be dependent on the particle size. Large particles (> 20 nm) tend to be incoherent and have a spherical shape, whereas small particles (< 10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles and multiple crystalline domains formed within a nanoparticle lead us to propose a three-stage mechanism to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels. Effects of nanoparticle size and density on cavity formation induced by (Fe{sup 8+} + He{sup +}) dual-beam irradiation are briefly addressed.

Hsiung, L; Fluss, M; Tumey, S; Kuntz, J; El-Dasher, B; Wall, M; Choi, W; Kimura, A; Willaime, F; Serruys, Y

2009-11-02

86

Preparation and characterization of Mg nanoparticles  

SciTech Connect

In this paper, Mg nanoparticles were prepared in tetrahydrofuran via lithium reduction of the corresponding Mg salt. X-ray diffraction and scanning electron microscope investigations confirm the formation of hexagonal phase Mg particles with an average size of 300 nm. X-ray photoelectron spectrometer analysis indicates that the as-prepared Mg nanoparticles are covered with a protecting layer consisting of residue solvents, naphthalene and Mg(OH){sub 2}, which slows down further oxidation under ambient conditions. Thermal analysis shows that the rapid oxidation and nitridation processes of the particles take place at around 500 deg. C and 553 deg. C, respectively. Furthermore, the addition of a small amount of magnesium nanoparticles remarkably catalyzes the decomposition process of ammonium perchlorate by lowering the decomposition temperature and enhancing its heat output.

Song Meirong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Laboratory for Special Functionary Materials, Henan University, Kaifeng, 475001 (China); Graduate School of the Chinese Academy of Sciences, Beijing, 100049 (China); Chen Miao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)], E-mail: miaochen@lzb.ac.cn; Zhang Zhijun [Laboratory for Special Functionary Materials, Henan University, Kaifeng, 475001 (China)

2008-05-15

87

Microwave absorption properties of conducting polymer composite with barium ferrite nanoparticles in 12.4-18 GHz  

NASA Astrophysics Data System (ADS)

Conducting polymer nanocomposites of polyphenyl amine with barium ferrite nanoparticles (50-70nm) have been synthesized via emulsion polymerization. The complex permittivity, permeability, and microwave absorption properties of the composite were studied in the 12.4-18GHz (Ku band) frequency range. The composite has shown high shielding effectiveness due to absorption (SEA) of 28.9dB (˜99.9%), which strongly depends on dielectric loss, magnetic permeability, and volume fraction of barium ferrite nanoparticles. The high value of SEA suggests that these composites can be used as a promising radar absorbing materials.

Ohlan, Anil; Singh, Kuldeep; Chandra, Amita; Dhawan, S. K.

2008-08-01

88

Synchrotron study on load partitioning between ferrite/martensite and nanoparticles of a 9Cr ODS steel  

NASA Astrophysics Data System (ADS)

Oxide dispersion strengthened (ODS) steels exhibit exceptional radiation resistance and high-temperature creep strength when compared to traditional ferritic and ferritic/martensitic (F/M) steels. Their excellent mechanical properties result from very fine nanoparticles dispersed within the matrix. In this work, we applied a high-energy synchrotron radiation X-ray to study the deformation process of a 9Cr ODS steel. The load partitioning between the ferrite/martensite and the nanoparticles was observed during sample yielding. During plastic deformation, the nanoparticles experienced a dramatic loading process, and the internal stress on the nanoparticles increased to a maximum value of 3.7 GPa, which was much higher than the maximum applied stress (?986 MPa). After necking, the loading capacity of the nanoparticles was significantly decreased due to a debonding of the particles from the matrix, as indicated by a decline in lattice strain/internal stress. Due to the load partitioning, the ferrite/martensite slightly relaxed during early yielding, and slowly strained until failure. This study develops a better understanding of loading behavior for various phases in the ODS F/M steel.

Mo, Kun; Zhou, Zhangjian; Miao, Yinbin; Yun, Di; Tung, Hsiao-Ming; Zhang, Guangming; Chen, Weiying; Almer, Jonathan; Stubbins, James F.

2014-12-01

89

Antimicrobial function of Nd3+-doped anatase titania-coated nickel ferrite composite nanoparticles: a biomaterial system.  

PubMed

The present study describes and makes a relative comparison of the antimicrobial function of undoped and neodymium-doped titania coated-nickel ferrite composite nanoparticles processed by uniquely combining the reverse micelle and chemical hydrolysis approaches. This methodology facilitates the formation of undoped and doped photocatalytic titania shells and a magnetic ferrite core. The ferrite core is needed to help in the removal of particles from the sprayed surface using a small magnetic field. Doping of the titania shell with neodymium significantly enhances the photocatalytic and anti-microbial function of the core-shell composite nanoparticles without influencing the magnetic characteristics of the nickel ferrite core. The increased performance is believed to be related to the inhibition of electron-hole recombination and a decrease in the band gap energy of titania. The retention of magnetic strength ensures controlled movement of the composite nanoparticles by the magnetic field, facilitating their application as removable anti-microbial photocatalyst nanoparticles. The consistent behavior of the composite nanoparticles points to the viability of the synthesis process adopted. PMID:16765882

Rana, S; Rawat, J; Sorensson, M M; Misra, R D K

2006-07-01

90

Synthesis of nickel–zinc ferrite magnetic nanoparticle and dye degradation using photocatalytic ozonation  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Nickel–zinc ferrite magnetic nanoparticle (NZFMN) was synthesized and characterized. ? Dye degradation by photocatalytic ozonation using NZFMN was studied. ? Formate, acetate and oxalate were detected as dominant dye degradation aliphatic intermediates. ? Nitrate, sulfate and chloride ions were detected as mineralization products of dyes. ? NZFMN was an effective magnetic nanocatalyst to degrade dyes. -- Abstract: In this paper, nickel–zinc ferrite magnetic nanoparticle (NZFMN) was synthesized and its dye degradation ability using photocatalytic ozonation was investigated. The NZFMN was characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM), Fourier transforms infrared (FTIR) and alternative gradient force magnetometer (AGFM). Reactive Red 198 (RR198) and Direct Green 6 (DG6) were used as dye models. UV–vis and ion chromatography (IC) analyses were employed to study dye degradation. The effects of operational parameters on decolorization such as NZFMN dosage, dye concentration, salt and pH were studied. RR198 and DG6 were completely decolorized (100%) by photocatalytic ozonation using NZFMN. Formate, acetate and oxalate anions were detected as dominant aliphatic intermediates. Nitrate, sulfate and chloride ions were detected as mineralization products of dyes. Results showed that the photocatalytic ozonation using NZFMN was a very effective method for dye degradation.

Mahmoodi, Niyaz Mohammad, E-mail: mahmoodi@icrc.ac.ir [Department of Environmental Research, Institute for Color Science and Technology, Tehran (Iran, Islamic Republic of); Bashiri, Marziyeh; Moeen, Shirin Jebeli [Department of Environmental Research, Institute for Color Science and Technology, Tehran (Iran, Islamic Republic of)] [Department of Environmental Research, Institute for Color Science and Technology, Tehran (Iran, Islamic Republic of)

2012-12-15

91

Method for preparing spherical ferrite beads and use thereof  

DOEpatents

The invention allows the fabrication of small, dense, highly polished spherical beads of hexagonal ferrites with selected compositions for use in nonreciprocal microwave and mm-wave devices as well as in microwave absorbent or reflective coatings, composites, and the like. A porous, generally spherical bead of hydrous iron oxide is made by a sol-gel process to form a substantially rigid bead having a generally fine crystallite size and correspondingly finely distributed internal porosity. The resulting gel bead is washed and hydrothermally reacted with a soluble alkaline earth salt (typically Ba or Sr) under conditions of elevated temperature and pressure to convert the bead into a mixed hydrous iron-alkaline earth oxide while retaining the generally spherical shape. This mixed oxide bead is then washed, dried, and calcined to produce the desired (BaFe.sub.12 O.sub.19 or SrFe.sub.12 O.sub.19) crystal structure. The calcined bead is then sintered to form a dense bead of the BaFe.sub.12 O.sub.19 and SrFe.sub.12 O.sub.19 phase suitable for polishing and incorporation into various microwave devices and components.

Lauf, Robert J. (Oak Ridge, TN); Anderson, Kimberly K. (Knoxville, TN); Montgomery, Frederick C. (Oak Ridge, TN); Collins, Jack L. (Knoxville, TN)

2002-01-01

92

Janus nanoparticles: preparation, characterization, and applications.  

PubMed

In chemical functionalization of colloidal particles, the functional moieties are generally distributed rather homogeneously on the particle surface. Recently, a variety of synthetic protocols have been developed in which particle functionalization may be carried out in a spatially controlled fashion, leading to the production of structurally asymmetrical particles. Janus particles represent the first example in which the two hemispheres exhibit distinctly different chemical and physical properties, which is analogous to the dual-faced Roman god, Janus. Whereas a variety of methods have been reported for the preparation of (sub)micron-sized polymeric Janus particles, it has remained challenging for the synthesis and (unambiguous) structural characterization of much smaller nanometer-sized Janus particles. Herein, several leading methods for the preparation of nanometer-sized Janus particles are discussed and the important properties and applications of these Janus nanoparticles in electrochemistry, sensing, and catalysis are highlighted. Some perspectives on research into functional patchy nanoparticles are also given. PMID:24376180

Song, Yang; Chen, Shaowei

2014-02-01

93

Preparation of medical magnetic nanobeads with ferrite particles encapsulated in a polyglycidyl methacrylate (GMA) for bioscreening  

NASA Astrophysics Data System (ADS)

Ferrite nanoparticles (an intermediate between Fe3O4 and ?-Fe2O3), ˜7nm in diameter, were embedded in beads of a mixed polymer of styrene (St) and glycidyl methacrylate (GMA) by emulsifier-free emulsion polymerization method. The beads were coated with GMA by a seeded polymerization method in order to suppress nonspecific protein binding on the surfaces; GMA exhibits very low nonspecific protein binding, which is required for carriers used for bioscreening. The beads have diameters of 180±50nm and saturation magnetizations of 28emu /g, exceeding commercially available polymer-coated beads of micron size having a weaker saturation magnetization (˜12emu/g).

Nishibiraki, H.; Kuroda, C. S.; Maeda, M.; Matsushita, N.; Abe, M.; Handa, H.

2005-05-01

94

Polysaccharide-covered nanoparticles prepared by nanoprecipitation  

Microsoft Academic Search

Dextran-covered poly(lactic acid) (PLA) nanoparticles were prepared using the nanoprecipitation process. Two alternative procedures were compared. On the one hand, PLA was nanoprecipitated in the presence of dextran-based polymeric stabilizer. On the other hand, a PLA-grafted dextran copolymer was nanoprecipitated without the addition of any external stabilizer. The characteristics of particles (yield, size, colloidal stability in the presence of salt)

Cècile Gavory; Alain Durand; Jean-Luc Six; Cècile Nouvel; Emmanuelle Marie; Michèle Leonard

2011-01-01

95

Synthesis, magnetic and optical properties of core/shell Co1- x Zn x Fe2O4/SiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

The optical properties of multi-functionalized cobalt ferrite (CoFe2O4), cobalt zinc ferrite (Co0.5Zn0.5Fe2O4), and zinc ferrite (ZnFe2O4) nanoparticles have been enhanced by coating them with silica shell using a modified Stöber method. The ferrites nanoparticles were prepared by a modified citrate gel technique. These core/shell ferrites nanoparticles have been fired at temperatures: 400°C, 600°C and 800°C, respectively, for 2 h. The composition, phase, and morphology of the prepared core/shell ferrites nanoparticles were determined by X-ray diffraction and transmission electron microscopy, respectively. The diffuse reflectance and magnetic properties of the core/shell ferrites nanoparticles at room temperature were investigated using UV/VIS double-beam spectrophotometer and vibrating sample magnetometer, respectively. It was found that, by increasing the firing temperature from 400°C to 800°C, the average crystallite size of the core/shell ferrites nanoparticles increases. The cobalt ferrite nanoparticles fired at temperature 800°C; show the highest saturation magnetization while the zinc ferrite nanoparticles coated with silica shell shows the highest diffuse reflectance. On the other hand, core/shell zinc ferrite/silica nanoparticles fired at 400°C show a ferromagnetic behavior and high diffuse reflectance when compared with all the uncoated or coated ferrites nanoparticles. These characteristics of core/shell zinc ferrite/silica nanostructures make them promising candidates for magneto-optical nanodevice applications.

Girgis, Emad; Wahsh, Mohamed Ms; Othman, Atef Gm; Bandhu, Lokeshwar; Rao, Kv

2011-07-01

96

A low loss NiZnCo ferrite, prepared using a hydrothermal method, for antenna applications  

NASA Astrophysics Data System (ADS)

In this paper, a novel low-loss NiZnCo ferrite prepared by a hydrothermal method has been developed for miniaturization and performance enhancement of mobile handset antennae. XRD analysis revealed that in weakly alkaline solution, H+ ions generated in the reaction process result in an acid-alkali imbalance. In a strongly alkaline solution, Fe(OH)3 readily loses water to generate ?-Fe2O3 and is no longer able to act as a nucleation skeleton. With powders prepared at pH = 10, the ceramic samples consisted of a pure phase, with compact and uniform microstructure, leading to relatively high permeability, very low dielectric constant, and with low losses. A miniaturization factor of about 6.2 and normalized impedance of about 1 were obtained for the developed substrate ferrite when used in a helical antenna operating in the terrestrial digital multimedia broadcasting (T-DMB) band for a mobile handset.

Chen, Kang; Jia, Lijun; Yu, Xianghai; Zhang, Huaiwu

2014-05-01

97

Preparation of spinel-type ferrite thin films by the dip-coating process and their magnetic properties  

Microsoft Academic Search

Films of spinel-type ferrite, MFe2O4 (M=Ni, Co, Mg, Li0.5Fe0.5) have been prepared by a dip-coating method from the sol-gel process. Ferric nitrate, nickel nitrate, cobalt nitrate and lithium nitrate were used as raw materials, and glycerol and formamide were used as solvents. A film was prepared by dipping a silica glass plate. The spinel-type ferrite was obtained by heat-treatment at

T. Tsuchiya; H. Yamashiro; T. Sei; T. Inamura

1992-01-01

98

Preparation and magnetic property analysis of monodisperse Co–Zn ferrite nanospheres  

Microsoft Academic Search

Monodisperse Co–Zn ferrite (Co1?xZnxFe2O4) nanospheres have been synthesized by the solvothermal method. In this process, glycol was used as a solvent, anhydrous sodium acetate was used as an alkalinity additive and polyethylene glycol 200 was used as a surfactant. The as-prepared samples were characterized in detail by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM),

Chengyi Hou; Hao Yu; Qinghong Zhang; Yaogang Li; Hongzhi Wang

2010-01-01

99

Modified nanoprecipitation method for polysulfone nanoparticles preparation.  

PubMed

Towards developing a more universal and productive nanoprecipitation processes, we focus on the preparation of polysulfone (PSF) nanoparticles through instantaneous solvent displacement in a metal membrane contactor between dimethylformamide (DMF) and water. In the original nanoprecipitation process, cubic nuclei can form instantaneously, but slow growth and aggregation have intensive interactions. Moreover, the reservation of DMF may enhance the adhesive effect between polymeric particles, causing severe particle aggregation. To overcome this difficulty, a modified nanoprecipitation method appending a quenching step was proposed. The well-dispersed PSF nanoparticles are successfully obtained when ethyl acetate is introduced. In this way, DMF can be extracted from water solution, thus facilitating the precipitating of PSF. Furthermore, selecting water as the continuous fluid, the particle size can be adjusted simply by tuning the operating parameters, including the PSF concentration in the dispersed fluid and the ratio of two feeds. Compared with previous reports on the continuous nanoprecipitation process for polymeric nanoparticles preparation, this work shows advantages including expanding the adaptability to more functional polymers, providing better flexibility on process or product development independent of the use of surfactant, and presenting a high throughput and easy-to-scale-up equipment platform. PMID:24643577

Liu, Y; Lu, Y C; Luo, G S

2014-05-21

100

Anatase TiO 2 nanolayer coating on cobalt ferrite nanoparticles for magnetic photocatalyst  

Microsoft Academic Search

TiO2\\/CoFe2O4 composite nanoparticles with a core–shell structure have been obtained. The core CoFe2O4 nanoparticles were synthesized via co-precipitation method, and the shell TiO2 nanocrystals were derived via sol–gel technology followed by heat-treatment at 450 °C. The morphology and the crystalline structure of composite nanoparticles were characterized by transmission electron microscopy (TEM) and X-ray diffraction, respectively. The as-prepared composite particles can

Wuyou Fu; Haibin Yang; Minghua Li; Minghui Li; Nan Yang; Guangtian Zou

2005-01-01

101

Aqueous synthesis and transmission electron microscopy observation of seed-grown spherical ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Uniform-sized spherical iron ferrite nanoparticles grew on seed crystals in an aqueous solution containing sucrose. Using the seed crystals which were highly dispersed in acidic or alkaline seed-crystal suspension without relation to pH of the suspension, we widely controlled the particle diameter in the range 20-200 nm by changing the additive amount of the seed crystals. By transmission electron microscopy observation and X-ray diffraction analysis, it indicated that the particles were highly crystalline but not amorphous. Selected area diffraction patterns of the particles by using transmission electron microscope revealed that the particles were composed of one to several crystals. Thus we provided the evidence that the particles grew on clusters composed of one to several seed crystals to which those of several dozen seed crystals were disintegrated.

Tanaka, T.; Tada, M.; Nakagawa, T.; Abe, M.

2012-03-01

102

Cellular distribution and degradation of cobalt ferrite nanoparticles in Balb/3T3 mouse fibroblasts.  

PubMed

The effect of the concentration of cobalt ferrite (CoFe(2)O(4)) nanoparticles (NPs) on their intracellular location and distribution has been explored by synchrotron radiation X-ray and fluorescence microscopy (SR-XRF) monitoring the evolution of NPs elemental composition as well. In cells exposed to low concentrations of CoFe(2)O(4) NPs, the NPs preferentially segregate in the perinuclear region preserving their initial chemical content. At concentrations exceeding 500 ?M the XRF spectra indicate the presence of Co and Fe also in the nuclear region, accompanied by sensible changes in the cellular morphology. The increase of the Co/Fe ratio measured in the nuclear compartment indicates that above certain concentrations the CoFe(2)O(4) NPs intracellular distribution could be accompanied by biodegradation resulting in Co accumulation in the nucleus. PMID:21925252

Marmorato, Patrick; Ceccone, Giacomo; Gianoncelli, Alessandra; Pascolo, Lorella; Ponti, Jessica; Rossi, François; Salomé, Murielle; Kaulich, Burkhard; Kiskinova, Maya

2011-11-30

103

Preparation of Fe/Ni Zn Cu ferrite stacked films by aerosol deposition method  

NASA Astrophysics Data System (ADS)

Composite or stacked films composed of Fe and Ni-Zn-Cu ferrite were prepared by aerosol deposition (AD) method, and the relationship between magnetic properties and microstructure was investigated. Aiming to control the microstructure, two aerosol chambers and double nozzles, from which each powder ejected independently, were used in the AD system. With increase in the vibration frequency of Fe aerosol chamber ( VFe) or the deposition time of Fe powder ( tFe), the Fe content in the films increased, which was resulted in the increase of saturation magnetization and permeability. The composite or stacked films also showed relatively high-noise suppression effect (? Ploss/ Pin=˜0.58). Microstructural analyses revealed that the stacked film consisted of Fe and ferrite layers with thickness of 1 and 15 ?m, respectively.

Sugimoto, S.; Chan, V.; Noguchi, M.; Tezuka, N.; Inomata, K.; Akedo, J.

2007-03-01

104

Pr 3+-substituted W-type barium ferrite: Preparation and electromagnetic properties  

NASA Astrophysics Data System (ADS)

The W-type ferrites doped with Pr 3+, BaCoNiPr xFe 16- xO 27 ( x=0-0.20), were prepared by a sol-gel method. The structure and electromagnetic properties of the samples are studied using powder X-ray diffraction, field emission scanning electron microscope, vibrating sample magnetometer and vector network analyzer. All the samples are hexagonal platelet-like W-type barium ferrite. These synthesized samples exhibit paramagnetism and strong magnetism. The saturation magnetization ( Ms) increases with the increase of Pr 3+ content. The real part of complex permittivity ( ?') decreases and the imaginary part ( ??) increases with Fe 3+ replaced by Pr 3+. The imaginary part of complex permittivity ( ??) increases and the real part ( ?') decreases after Pr 3+ is doped. Furthermore, the doped Pr 3+ improves the microwave absorbency.

Wu, Yanfei; Huang, Ying; Niu, Lei; Zhang, Yinling; Li, Yuqing; Wang, Xiaoya

2012-02-01

105

The preparation of magnetic nanoparticles for applications in biomedicine  

Microsoft Academic Search

This review is focused on describing state-of-the-art synthetic routes for the preparation of magnetic nanoparticles useful for biomedical applications. In addition to this topic, we have also described in some detail some of the possible applications of magnetic nanoparticles in the field of biomedicine with special emphasis on showing the benefits of using nanoparticles. Finally, we have addressed some relevant

Pedro Tartaj; M ar ´ õa del Puerto Morales; Sabino Veintemillas-Verdaguer; Teresita González-Carreño; Carlos J Serna

2003-01-01

106

Preparation and characterization of uniform near IR polystyrene nanoparticles.  

PubMed

Biomaterials for in vivo fluorescence imaging are required to be biocompatible, nontoxic, photostable and highly fluorescent. Fluorescence must be in the near infrared (NIR) region of the electromagnetic spectrum to avoid absorption and autofluorescence of endogenous tissues. NIR fluorescent polystyrene nanoparticles may be considered ideal biomaterials for in vivo imaging applications. These NIR nanoparticles were prepared by a swelling process of polystyrene template nanoparticles with a hydrophobic NIR dye dissolved in a water-miscible swelling solvent, a method developed for preparation of nonbiodegradable nanoparticles, for NIR fluorescent bioimaging applications. This method overcomes common problems that occur with dye entrapment during nanoparticle formation such as loss of fluorescence and size polydispersity. Fluorescence intensity of the nanoparticles was found to be size dependent, and was optimized for differently sized nanoparticles. The resulting NIR nanoparticles were also found to be more fluorescent and highly photostable compared to the free dye in solution, showing their potential as biomaterials for in vivo fluorescence imaging. PMID:24460556

Pellach, Michal; Margel, Shlomo

2014-01-01

107

Preparation of Pb-free silver paste containing nanoparticles  

Microsoft Academic Search

Pb-free silver paste containing nanoparticles was prepared for low temperature sintering. The silver nanoparticles with size of 20–50nm were synthesized by a chemical reduction method using surfactant. To prepare lead-free silver paste, 10wt% and 20wt% of the silver nanoparticles were added into conventional silver powder with an average particle size of 1.6?m. Then, 3wt% or 6wt% of lead-free frit was

Sunghyun Park; Dongseok Seo; Jongkook Lee

2008-01-01

108

Preparation of medical magnetic nanobeads with ferrite particles encapsulated in a polyglycidyl methacrylate (GMA) for bioscreening  

SciTech Connect

Ferrite nanoparticles (an intermediate between Fe{sub 3}O{sub 4} and {gamma}-Fe{sub 2}O{sub 3}), {approx}7 nm in diameter, were embedded in beads of a mixed polymer of styrene (St) and glycidyl methacrylate (GMA) by emulsifier-free emulsion polymerization method. The beads were coated with GMA by a seeded polymerization method in order to suppress nonspecific protein binding on the surfaces; GMA exhibits very low nonspecific protein binding, which is required for carriers used for bioscreening. The beads have diameters of 180{+-}50 nm and saturation magnetizations of 28 emu/g, exceeding commercially available polymer-coated beads of micron size having a weaker saturation magnetization ({approx}12 emu/g)

Nishibiraki, H.; Kuroda, C.S.; Maeda, M.; Matsushita, N.; Abe, M.; Handa, H. [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho Midori-ku, Yokohama 226-8503 (Japan)

2005-05-15

109

Study of hard-soft magnetic ferrite films prepared by pulsed laser deposition  

NASA Astrophysics Data System (ADS)

Soft magnetic Mg0.1Ni0.3Zn0.6Fe2O4 and hard magnetic BaFe12O19 bulk nanocrystalline ferrites were synthesized using the sol-gel auto-combustion method, and were used as targets to deposit soft-hard thin films by the pulsed laser deposition (PLD) method. Various soft-hard thin films with different preparation conditions were deposited on Si (100) substrate, which can be effectively utilized to get better magnetic properties. The prepared films were characterized by the X-ray diffraction (XRD), atomic force microscopy (AFM) and magnetic measurements. XRD confirms the presence of soft and hard phases in the thin films. Coercivity of the prepared films ranges from 1.67 to 2.66 kA/m. AFM images show clustering of grains at the film surface with a characteristic columnar growth.

Satalkar, M.; Kane, S. N.; Ghosh, A.; Raghuvanshi, S.; Tapkir, P.; Ghodke, N.; Phase, D. M.; Chaudhary, R. J.; Pasko, A.; LoBue, M.; Mazaleyrat, F.

2014-09-01

110

Tuning high aqueous phase uptake in nonionic water-in-oil microemulsions for the synthesis of Mn-Zn ferrite nanoparticles: phase behavior, characterization, and nanoparticle synthesis.  

PubMed

In this work, the formation of water-in-oil (w/o) microemulsions with high aqueous phase uptake in a nonionic surfactant system is investigated as potential media for the synthesis of Mn-Zn ferrite nanoparticles. A comprehensive study based on the phase behavior of systems containing precursor salts, on one hand, and precipitating agent, on the other hand, was carried out to identify key regions on (a) pseudoternary phase diagrams at constant temperature (50 °C), and (b) pseudobinary phase diagrams at constant surfactant (S):oil(O) weight ratio (S:O) as a function of temperature. The internal structure and dynamics of microemulsions were studied systematically by conductivity and self-diffusion coefficient determinations (FT PGSE (1)H NMR). It was found that nonpercolated w/o microemulsions could be obtained by appropriate tuning of composition variables and temperature, with aqueous phase concentrations as high as 36 wt % for precursor salts and 25 wt % for precipitating agent systems. Three compositions with three different dynamic behaviors (nonpercolated and percolated w/o, as well as bicontinuous microemulsions) were selected for the synthesis of Mn-Zn ferrites, resulting in nanoparticles with different characteristics. Spinel structure and superparamagnetic behavior were obtained. This study sets firm basis for a systematic study of Mn-Zn ferrite nanoparticle synthesis via different scenarios of microemulsion dynamics, which will contribute to a better understanding on the relationship of the characteristics of the obtained materials with the properties of the reaction media. PMID:22039992

Aubery, Carolina; Solans, Conxita; Sanchez-Dominguez, Margarita

2011-12-01

111

Nanocrystalline transition metal ferrite thin films prepared by an electrochemical route for Li-ion batteries  

NASA Astrophysics Data System (ADS)

Nanocrystalline ferrite MFe 2O 4 (M = Cu, Ni, Co) thin films have been prepared by an electrochemical route involving cathodic electrodeposition of MFe 2 alloys and further anodization of the alloy films at room temperature. XRD measurements showed that those films are polycrystalline with spinel tetragonal structure for CuFe 2O 4, and cubic structure for NiFe 2O 4 and CoFe 2O 4, respectively. The uniform MFe 2O 4 films without cracks and pinholes were observed in SEM measurement, and the estimated grain average sizes of as-prepared ferrite films were about 50 nm. The electrochemical measurements showed that MFe 2O 4 thin film electrodes delivered a reversible capacity of 450-460 mAh g -1 at 10 ?A cm -2 in the voltage range of 0.01-3.0 V and more than 75% reversible capacity still remained up to 100 cycles. Our results showed that MFe 2O 4 thin films could be used as promising anode materials for thin film lithium-ion batteries.

NuLi, Yan-Na; Qin, Qi-Zong

112

Preparation of drug nanoparticles by emulsion evaporation method  

NASA Astrophysics Data System (ADS)

Polymeric drug nanoparticles were prepared by emulsion solvent evaporation method. In this study, prepared the polymeric drug nanoparticles consist of ketoprofen and Eudragit E 100. The morphology structure was investigated by scanning electron microscopy (SEM). The interactions between the drug and polymer were investigated by Fourier transform infrared spectroscopy (FTIR). The size distribution was measured by means of Dynamic Light Scattering. The nanoparticles have an average size of about 150 nm. The incorporation ability of drugs in the polymeric nanoparticles depended on the integration between polymer and drug as well as the glass transition temperature of the polymer.

Hoa, Le Thi Mai; Chi, Nguyen Tai; Triet, Nguyen Minh; Thanh Nhan, Le Ngoc; Mau Chien, Dang

2009-09-01

113

Nanoparticles of Molybdenum Chlorophyllin Photosensitizer and Magnetic Citrate-Coated Cobalt Ferrite Complex Available to Hyperthermia and Photodynamic Therapy Clinical Trials  

NASA Astrophysics Data System (ADS)

This study report on the synthesis and characterization of molybdenum chlorophyllin (Mo-Chl) compounds associated in a complex with magnetic nanoparticles (citrate-coated cobalt ferrite), the latter prepared as a biocompatible magnetic fluid (MF). The complex material was developed for application as a synergic drug for cancer treatment using Photodynamic Therapy (PDT) and Hyperthermia (HPT). Chlorophyllin was obtained from alkaline extraction of Ilex paraguariensis following molybdenum insertion from hydrolysis with molybdate sodium. Fluorescence quantum yield (?f) of Mo-Chl/dimethyl-sulphoxide (DMSO) was lower than 0.1, with a lifetime of 5.0 ns, as obtained from time-correlated single-photon counting technique. The oxygen quantum yield of Mo-Chl was carried out using laser flash-photolysis studies in homogeneous medium saturated with O2(g) (?? = 0.50). Cellular viability was also evaluated via the classical MTT assay using gingival fibroblasts cells as a biological model. Studies performed with the complex Mo-Chl (5.0 ?mol.L-1)/MF at different magnetic nanoparticle concentrations (ranging from 1012 to 1015 particle.mL-1) revealed a cellular viability of approximately 95% for the ideal magnetic material concentration of 1×10 particle.mL-1. The present study shows that natural photosensitizers molecules Mo-Chl used in association with magnetic nanoparticles represent a promising generation of drug developed to work synergistically in the treatment of neoplastic tissues using PDT and HPT.

Primo, Fernando L.; Cordo, Paloma L. A. G.; Neto, Alberto F.; Morais, Paulo C.; Tedesco, Antonio C.

2010-12-01

114

Polyethylene glycol as an alternative polymer solvent for nanoparticle preparation.  

PubMed

Solvent toxicity is one of the major drawbacks in the preparation of polymeric nanoparticles today. Here, polyethylene glycols (PEGs) are proposed as non-toxic solvents for the preparation of polymeric nanoparticles. Based on a preparation process similar to the solvent displacement technique, several process parameters were examined for their effects on the properties of the prepared nanoparticles by this method to achieve the optimum preparation conditions. The investigated parameters included polymer type and concentration, volume and temperature of the dispersing phase, methods of dispersing the solvent phase into the non-solvent phase, duration and speed of stirring and washing by dialysis. Ammonio methacrylate copolymer (Eudragit RL), poly-lactide-co-glycolide (PLGA), and PEG-PLGA were found to be successful polymer candidates for the preparation of nanoparticles by this method. Nanoparticles with diameters ranging from 80 to 400 nm can be obtained. The encapsulation efficiencies of bovine serum albumin, and lysozyme as model proteins were ranging from 7.3±2.2% to 69.3±1.8% depending on the strength of polymer-protein interaction. Biological assays confirmed a full lysozyme activity after the preparation process. PEG proved to be a suitable non-toxic solvent for the preparation of polymeric protein-loaded nanoparticles, maintaining the integrity of protein. PMID:23958752

Ali, Mohamed Ehab; Lamprecht, Alf

2013-11-01

115

Preparation of SiC nanoparticles from plastic wastes  

Microsoft Academic Search

By a simple carbothermal reduction method, ?-SiC nanoparticles with different sizes were prepared from plastic wastes, water bottles and disposable boxes. These particles were characterized by X-ray diffraction, transmission electron microscopy, dynamic light scattering and so on. The SiC nanoparticles synthesized from water bottles mainly have dimensions in the range of 5–20nm, while the nanoparticles synthesized from disposable boxes mainly

Shuai Meng; Dong-Hua Wang; Guo-Qiang Jin; Ying-Yong Wang; Xiang-Yun Guo

2010-01-01

116

Adsorption of sulfur dioxide by CoFe2O4 spinel ferrite nanoparticles and corresponding changes in magnetism.  

PubMed

Adsorption of sulfur dioxide on 10 nm CoFe(2)O(4) spinel ferrite nanoparticles was examined. Adsorption loadings of sulfur dioxide at breakthrough conditions were determined to be approximately 0.62 mol/kg, which is significant given the 150 m(2)/g surface area of the nanoparticles. Adsorption proceeds through a chemisorption mechanism with sulfur dioxide forming a sulfate upon adsorption on the particle surface, which leads to a 23% decrease in the remnant magnetization, a 20% decrease in the saturation magnetization, and a 9% decrease in the coercivity of the magnetic nanoparticles. Adsorbent materials that provide a magnetic signal when adsorption occurs could have broad implications on adsorption-based separations. PMID:22400990

Glover, T Grant; Sabo, Daniel; Vaughan, Lisa A; Rossin, Joseph A; Zhang, Z John

2012-04-01

117

Preparation and bactericide activity of gallic acid stabilized gold nanoparticles  

Microsoft Academic Search

In this work, gold nanoparticles with three different sizes (13.7, 39.4, and 76.7 nm) were prepared using a simple aqueous\\u000a method with gallic acid as the reducing and stabilizing agent, the different sizes were obtained varying some experimental\\u000a parameters as the pH of the reaction and the amount of the gallic acid. The prepared nanoparticles were characterized using\\u000a X-ray diffraction, transmission

S. A. Moreno-Álvarez; G. A. Martínez-Castañón; N. Niño-Martínez; J. F. Reyes-Macías; N. Patiño-Marín; J. P. Loyola-Rodríguez; Facundo Ruiz

2010-01-01

118

Recent advances in the preparation of hybrid nanoparticles in miniemulsions.  

PubMed

In this review, we summarize recent advances in the synthesis of hybrid nanoparticles in miniemulsions since 2009. These hybrid nanoparticles include organic-inorganic, polymeric, and natural macromolecule/synthetic polymer hybrid nanoparticles. They may be prepared through encapsulation of inorganic components or natural macromolecules by miniemulsion (co)polymerization, simultaneous polymerization of vinyl monomers and vinyl-containing inorganic precursors, precipitation of preformed polymers in the presence of inorganic constituents through solvent displacement techniques, and grafting polymerization onto, from or through natural macromolecules. Characterization, properties, and applications of hybrid nanoparticles are also discussed. PMID:24951391

Qi, Dongming; Cao, Zhihai; Ziener, Ulrich

2014-09-01

119

Preparation and characterization of 4-dimethylaminopyridine-stabilized palladium nanoparticles.  

PubMed

4-Dimethylaminopyridine (DMAP)-stabilized palladium nanoparticles with a mean diameter of 3.4 +/- 0.5 nm are prepared from the aqueous phase reduction of Na2PdCl4 using NaBH4 in the presence of DMAP. TEM and UV-vis spectroscopy characterization of the nanoparticle dispersion shows no obvious change in the nanoparticles several months after preparation. 1H NMR spectroscopy of the nanoparticles shows that the nanoparticle dispersion also contains a boron/DMAP complex and two palladium/DMAP complexes. One of the palladium complexes crystallizes out of the dispersion and is identified as Pd(DMAP)4(OH)2 by X-ray crystallography. Following extensive analysis, it is believed that the palladium/DMAP complexes are formed following the oxidation of the palladium nanoparticles. The prepared nanoparticle dispersion promotes selective hydrogen/deuterium (H/D) exchange on the carbon atoms alpha to the endocyclic nitrogen atom on the DMAP-stabilizing ligands through reaction with D2O. This activity is attributed to the presence of the nanoparticles rather than to the presence of the oxidized palladium/DMAP complexes. PMID:17985937

Flanagan, Keith A; Sullivan, James A; Müeller-Bunz, Helge

2007-12-01

120

Antifungal activity of gold nanoparticles prepared by solvothermal method  

SciTech Connect

Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m{sup 2}/g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ? Effect of reducing agents on the morphology of gold nanoparticles. ? Highly uniform and monodisperse gold nanoparticles (7 nm). ? Highest surface area of gold nanoparticles (329 m{sup 2/}g). ? Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl{sub 2} and NaBH{sub 4} as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl{sub 2}, however, NaBH{sub 4} produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m{sup 2}/g for 7 nm and 269 m{sup 2}/g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H{sup +} efflux of the Candida species than 15 nm sized gold nanoparticles.

Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India)] [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India)] [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Manzoor, Nikhat; Ahmad, Aijaz [Department of Biosciences, Jamia Millia Islamia, New Delhi 110025 (India)] [Department of Biosciences, Jamia Millia Islamia, New Delhi 110025 (India); Ahmed, Jahangeer [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States)] [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Al-Shihri, Ayed S. [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia)] [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia)

2013-01-15

121

Environmentally friendly preparation of metal nanoparticles  

EPA Science Inventory

The book chapter summarizes the ?state of the art? in the exploitation of various environmentally-friendly synthesis approaches, reaction precursors and conditions to manufacture metal and metal oxide nanoparticles for a vast variety of purposes....

122

Preparation of Silica Microspheres Containing Ag Nanoparticles  

Microsoft Academic Search

Two sol-gel fabrication processes were investigated to make silica spheres containing Ag nanoparticles: (1) a modified Stöber method for silica spheres below 1 µm size, and (2) a SiO2-film formation method on spheres of 3–;7 µm size. The spheres were designed to incorporate silver nanoparticles of high ?(3) in a spherical optical cavity structure for the resonance effect. For the

S. Shibata; K. Aoki; T. Yano; M. Yamane

1998-01-01

123

Electrospinning preparation, characterization and magnetic properties of cobalt-nickel ferrite (Co(1-x)Ni(x)Fe2)O4) nanofibers.  

PubMed

Uniform Co(1-)(x)Ni(x)Fe(2)O(4) (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) nanofibers with average diameter of 110 nm and length up to several millimeters were prepared by calcination of electrospun precursor nanofibers containing polymer and inorganic salts. The as-spun and calcined nanofibers were characterized in detail by TG-DTA, XRD, FE-SEM, TEM, SAED and VSM, respectively. The effect of composition of the nanofibers on the structure and magnetic properties were investigated. The nanofibers are formed through assembling magnetic nanoparticles with poly(vinyl pyrrolidone) as the structure-directing template. The structural characteristics and magnetic properties of the resultant nanofibers vary with chemical composition and can be tuned by adjusting the Co/Ni ratio. Both lattice parameter and particle size decrease gradually with increasing nickel concentration. The saturation magnetization and coercivity lie in the range 29.3-56.4 emu/g and 210-1255 Oe, respectively, and both show a monotonously decreasing behavior with the increase in nickel concentration. Such changes in magnetic properties can mainly be attributed to the lower magnetocrystalline anisotropy and the smaller magnetic moment of Ni(2+) ions compared to Co(2+) ions. Furthermore, the coercivity of Co-Ni ferrite nanofibers is found to be superior to that of the corresponding nanoparticle counterparts, presumably due to their large shape anisotropy. These novel one-dimensional Co-Ni ferrite magnetic nanofibers can potentially be used in micro-/nanoelectronic devices, microwave absorbers and sensing devices. PMID:22456275

Xiang, Jun; Chu, Yanqiu; Shen, Xiangqian; Zhou, Guangzhen; Guo, Yintao

2012-06-15

124

Synthesis and magnetic characterization of cobalt-substituted ferrite (Co xFe 3-xO 4) nanoparticles  

NASA Astrophysics Data System (ADS)

Cobalt-substituted ferrite nanoparticles were synthesized with a narrow size distribution using reverse micelles formed in the system water/AOT/isooctane. Fe:Co ratios of 3:1, 4:1, and 5:1 were used in the synthesis, obtaining cobalt-substituted ferrites (Co xFe 3-xO 4) and some indication of ?-Fe 3O 4 when 4:1 and 5:1 Fe:Co ratios were used. Inductively coupled plasma mass spectroscopy (ICP-MS) verified the presence of cobalt in all samples. Fourier transform infrared (FTIR) showed bands at ˜560 and ˜400 cm -1, characteristic of the metal-oxygen bond in ferrites. Transmission electron microscopy showed that the number median diameter of the particles was ˜3 nm with a geometric deviation of ˜0.2. X-ray diffraction (XRD) confirmed the inverse spinel structure typical of ferrites with a lattice parameter of a=8.388 Å for Co 0.61Fe 0.39O 4, which is near that of CoFe 2O 4 ( a=8.394 Å). Magnetic properties were determined using a superconducting quantum interference device (SQUID). Coercivities higher than 8 kOe were observed at 5 K, whereas at 300 K the particles showed superparamagnetic behavior. The anisotropy constant was determined based on the Debye model for a magnetic dipole in an oscillating field and an expression relating ?' and the temperature of the in-phase susceptibility peak. Anisotropy constant values in the order of ˜10 6 erg/cm 3 were determined using the Debye model, whereas anisotropy constants in the order of ˜10 7 erg/cm 3 were calculated assuming ??=1 at the temperature peak of the in-phase component of the susceptibility curve as commonly done in the literature. Our analysis demonstrates that the assumption ??=1 at the temperature peak of ?' is rigorously incorrect.

Calero-DdelC, Victoria L.; Rinaldi, Carlos

2007-07-01

125

Anhydride functionalised calcium ferrite nanoparticles: A new selective magnetic material for enrichment of lead ions from water and food samples.  

PubMed

In this research a sonochemistry route for manufacture of uniform nanocrystalline CaFe2O4 and its anhydride functionalisation were reported. The potential of raw and modified material as a magnetically separable sorbent in selective enrichment of lead ions from water and food samples is outlined. This material was characterised using FT-IR, XRD, SEM and VSM techniques. The SEM and VSM results indicated that the calcium ferrite nanoparticles are sphere-like particles possessing superparamagnetic properties with an average diameter of 40nm. Various analytical parameters, including pH, contact time, type and concentration of eluent, adsorption capacity, sample volume and interference of ions, were optimised. Following a modification by anhydride, calcium ferrite selectivity toward lead ions was raised more than twofold compared to the unmodified nanoparticles. Finally a pre-concentration procedure was applied for determination of trace Pb(II) in canned tuna fish, canned tomato paste, parsley, milk and well-water samples with satisfactory results. PMID:25306327

Pirouz, Mojgan Jafari; Beyki, Mostafa Hossein; Shemirani, Farzaneh

2015-03-01

126

Low temperature-fired Ni-Cu-Zn ferrite nanoparticles through auto-combustion method for multilayer chip inductor applications  

PubMed Central

Ferrite nanoparticles of basic composition Ni0.7-xZnxCu0.3Fe2O4 (0.0 ? x ? 0.2, x = 0.05) were synthesized through auto-combustion method and were characterized for structural properties using X-ray diffraction [XRD], scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy [FT-IR]. XRD analysis of the powder samples sintered at 600°C for 4 h showed the cubic spinel structure for ferrites with a narrow size distribution from 28 to 32 nm. FT-IR showed two absorption bands (v1 and v2) that are attributed to the stretching vibration of tetrahedral and octahedral sites. The effect of Zn doping on the electrical properties was studied using dielectric and impedance spectroscopy at room temperature. The dielectric parameters (?', ??, tan?, and ?ac) show their maximum value for 10% Zn doping. The dielectric constant and loss tangent decrease with increasing frequency of the applied field. The results are explained in the light of dielectric polarization which is similar to the conduction phenomenon. The complex impedance shows that the conduction process in grown nanoparticles takes place predominantly through grain boundary volume. PACS: 75.50.Gg; 78.20; 77.22.Gm. PMID:22316055

2012-01-01

127

Structural, dielectric and magnetic properties of cobalt ferrite prepared using auto combustion and ceramic route  

NASA Astrophysics Data System (ADS)

Cobalt ferrite is synthesized by using low temperature auto combustion and high temperature ceramic methods. The prepared samples have values of lattice constant equal to 8.40 Å and 8.38 Å for auto combustion and ceramic methods respectively. The FTIR spectrum of samples of the auto combustion method shows a high frequency vibrational band at 580 cm-1 assigned to tetrahedral site and a low frequency vibrational band at 409 cm-1 assigned to octahedral site which are shifted to 590 cm-1 and 412 cm-1 for the ceramic method sample. SEM micrographs of samples show a substantial difference in surface morphology and size of the grains between the two methods. The frequency dependent dielectric constant and ac conductivity of the samples measured from 1 Hz to 2 MHz at room temperature are reported. The room temperature magnetic hysteresis parameters of the samples are measured using VSM. The measured values of saturation magnetization, coercivity and remanent magnetization are 42 emu/g, 1553 Oe, 18.5 emu/g for the auto combustion method, 66.7 emu/g, 379.6 Oe, and 17.3 emu/g for the ceramic method, respectively. The difference in preparation methods and size of the grains causes interesting changes in electrical and magnetic properties.

Murugesan, C.; Perumal, M.; Chandrasekaran, G.

2014-09-01

128

Preparation of Chitosan Nanoparticles: A Study of Influencing Factors  

NASA Astrophysics Data System (ADS)

Chitosan (CS), a cationic polysaccharide, offers great advantages for ionic interactions with negatively charged species such as sodium tripolyphosphate (STPP) leading to the formation of biocompatible crosslinked chitosan nanoparticles In the present work, an attempt has been made to systematically study the following factors influencing the ionotropic gelation of chitosan with STPP to produce CS nanoparticles: effect of pH of solution, CS concentration, STPP concentration and CS/STPP ratio. The results show that with the increase in CS concentration, the yield of the nanoparticle decreases whereas size increases. The mean size of the prepared nanoparticles varied between 120 to 720 nm and zeta potential between +14 mV to +53 mV. Nanoparticle size and yield was found to be strongly dependent on solution pH. Nanoparticle size decreased with increase in solution pH from 4 to 5 and yield was found to be maximum at pH = 5. With increase in STPP concentration, the size and yield of the nanoparticle increased. The potential of CS nanoparticles to trap amoxicillin trihydrate, taken as the model drug, was also studied. The maximum drug loading capacity was found to be 35% at a solution pH = 5 for 0.2% CS and 0.086% STPP.

Thakur, Anupama; Taranjit

2011-12-01

129

Preparation and characterization of hollow glass microspheres coated by CoFe{sub 2}O{sub 4} nanoparticles using urea as precipitator via coprecipitation method  

SciTech Connect

The composite of hollow glass microspheres coated by CoFe{sub 2}O{sub 4} nanoparticles has been successfully prepared using urea as precipitator via coprecipitation method. The resultant composites were characterized by X-ray diffraction, field emission scanning electron microscope and vibrating sample magnetometer. The results showed that the slow decomposition of urea could be beneficial to form uniform and entire cobalt ferrite coating layer on the surface of hollow glass microspheres. The smoothest morphology was obtained for the sample prepared from 0.7 M urea, while the sample prepared from 1.0 M urea had the thickest shell. This indicated that there was a competition between the morphology and thickness of the coated microspheres. A possible formation mechanism of hollow glass microspheres coated with cobalt ferrite was proposed. The magnetic properties of the samples were also investigated.

Pang Xiaofen; Fu Wuyou [National Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Yang Haibin [National Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China)], E-mail: yanghb@jlu.edu.cn; Zhu Hongyang; Xu Jing [National Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Li Xiang [Institute of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454003 (China); Zou Guangtian [National Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China)

2009-02-04

130

Study on the preparation of Mn–Zn soft magnetic ferrite powders from waste Zn–Mn dry batteries  

Microsoft Academic Search

Using waste Zn–Mn dry batteries, waste scrap iron and pyrolusite as raw materials, Mn–Zn soft magnetic ferrite powders were prepared through the process of simultaneous leaching, purification and co-precipitation. The experimental results indicated that the leached yields of Fe, Mn and Zn were 92.02%, 96.14% and 98.34%, respectively. The leached liquor was purified through these processes of sulfuration precipitation, fluorination

Chang-hong Peng; Ben-shuai Bai; Yi-feng Chen

2008-01-01

131

Preparation of size-controlled bovine serum albumin (BSA) nanoparticles by a modified desolvation method  

Microsoft Academic Search

The size effect of nanomaterials is of major interest, since it may affect their bioavailability and toxicity. In this study, bovine serum albumin (BSA) nanoparticles were prepared using a modified desolvation method. Bare BSA nanoparticles and calcium (Ca)-loaded BSA nanoparticles were fabricated at the targeted sizes, 100, 400, and 800nm. The mean diameters of the prepared BSA nanoparticles were 125,

Ji Yeon Jun; Hoang Hai Nguyen; Sae-Yeol-Rim Paik; Hyang Sook Chun; Byeong-Cheol Kang; Sanghoon Ko

2011-01-01

132

Magnetically driven micropump produced by microstereolithography with ferrite nanoparticle composite photopolymer  

Microsoft Academic Search

A photopolymer containing magnetic nanoparticles was developed for applying magnetically driven micromachines. 7-nm diameter gamma-Fe2O3 nanoparticles coated by amorphous-SiO2 was used. The concentration of the magnetic nanoparticles was optimized by ultraviolet exposure. A magnetic microrotor of 6 mm diameter was produced by a molding process with a three-dimensional master model produced by microstereolithography using the nanoparticle composite photopolymer. A viscous

S. Maruo; T. Saeki; Y. Kanazawa; Y. Ichiyanagi

2008-01-01

133

Structure and magnetic properties of Co and Ni nano-ferrites prepared by a two step direct microemulsions synthesis  

NASA Astrophysics Data System (ADS)

Nano-particles of CoFe2O4, NiFe2O4 and Co0.5Ni0.5Fe2O4 were synthesized by a two step microemulsion precipitation where inverse micelles of water in hexanol were stabilized using cetyltrimethylammonium bromide. Powder X-ray diffraction analysis and Transmission electron microscopy measurements provided data to clarify the crystal structure and size of the produced nano-particles. Different measurements of magnetic properties at low temperatures of 2 K revealed that nano-particles of NiFe2O4 represent magnetically soft ferrite with a coercivity ?40 kA/m, whereas nano-particles of CoFe2O4 and Co0.5Ni0.5Fe2O4 were magnetically harder with a coercivity of 815 and 947 kA/m, respectively. Additionally zero field cooling and field cooling measurements provided data for estimating the blocking temperature of the materials produced. For NiFe2O4 this temperature is lower, 23 K. The blocking temperature of CoFe2O4 of 238 K and Co0.5Ni0.5Fe2O4 of 268 K are higher in comparison with NiFe2O4.

Pulišová, P.; Ková?, J.; Voigt, A.; Raschman, P.

2013-09-01

134

Ni-Zn ferrite films with high permeability (?'=˜30, ??=˜30) at 1 GHz prepared at 90 °C  

NASA Astrophysics Data System (ADS)

Ni-Zn ferrite films were prepared by spin-spray ferrite plating method at 90 °C on glass substrates from a reaction solution of FeCl2(+FeCl3)+NiCl2+ZnCl2 and an oxidizing solution of NaNO2+CH3COONH4. The complex permeability ?=?'-i?? values of the as-plated films were measured at frequencies up to 3 GHz. The Ni0.28Zn0.18Fe2.54O4 film 0.40 ?m in thickness plated using the mixture of Fe2+ and Fe3+ as iron ions exhibited a high ?' of around 42 and a resonance frequency fr of 1.2 GHz. This fr value is about nine times as high as the 130 MHz that was estimated from Snoek's limit for the Ni-Zn ferrite bulk ceramics. Since ?' also exhibited a maximum value of about 35, the films prepared in this study will be applicable to both rf inductors and wave absorbers for electromagnetic interference suppression.

Matsushita, N.; Chong, C. P.; Mizutani, T.; Abe, M.

2002-05-01

135

High frequency magneto-dielectric effects in self-assembled ferrite-ferroelectric core-shell nanoparticles  

NASA Astrophysics Data System (ADS)

Magneto-dielectric effects in self-assembled core-shell nanoparticles of nickel ferrite (NFO) and barium titanate (BTO) have been investigated in the millimeter wave frequencies. The core-shell nano-composites were synthesized by coating 100 nm nickel ferrite and 50 nm barium titanate nanoparticles with complementary coupling groups and allowing them to self-assemble in the presence of a catalyst forming heterogeneous nanocomposites. Magneto-electric (ME) characterization of as-assembled particles has been carried out by measurements of the relative permittivity ?r as a function of frequency f under an applied static magnetic field H over 16-24 GHz. Measurements show an H-induced decrease in ?r of 1 to 1.5%. But a giant magneto-dielectric effect with an H-induced change in permittivity as high as 28% is measured under dielectric resonance in the samples. A strong ME coupling was also evident from H-tuning of dielectric resonance in the composites. A theory for the high frequency magneto-dielectric effect has been developed and consists of the following steps. First the Bruggeman model is used to estimate the effective dielectric constant for the shell consisting of the BTO particles and voids considered as spherical air-pores. Then the permittivity for the core and shell is estimated taking into consideration the sample porosity. Finally the H-dependence of the permittivity due to ME interactions is calculated from the free energy considerations. Estimated ?r vs. H and dielectric resonance frequency vs. H characteristics are in general agreement with the data.

Popov, M.; Sreenivasulu, G.; Petrov, V. M.; Chavez, F. A.; Srinivasan, G.

2014-09-01

136

Exchange bias properties and surface spins freezing in ferrite nanoparticles of magnetic nanocolloids  

Microsoft Academic Search

We investigate magnetic nanocolloids based on 3.3 nm sized particles of manganese ferrite. The observation of shifted hysteresis loops after cooling the sample in high fields indicates the existence of a coupling between the ferrimagnetic ordered core and the disordered surface layer. The exchange bias field, determined from the field offset from the origin, decreases as the cooling field increases.

F. G. Silva; R. Aquino; V. Dupuis; J. Depeyrot; F. A. Tourinho; R. Perzynski

2010-01-01

137

Structure, morphology and magnetic properties of Mg(x) Zn(1 - x)Fe2O4 ferrites prepared by polyol and aqueous co-precipitation methods: a low-toxicity alternative to Ni(x)Zn(1 - x)Fe2O4 ferrites  

NASA Astrophysics Data System (ADS)

The synthesis and properties of Mg(x)Zn(1 - x)Fe2O4 spinel ferrites as a low-toxicity alternative to the technologically significant Ni(x)Zn(1 - x)Fe2O4 ferrites are reported. Ferrite nanoparticles have been formed through both the polyol and aqueous co-precipitation methods that can be readily adapted to industrial scale synthesis to satisfy the demand of a variety of commercial applications. The structure, morphology and magnetic properties of Mg(x)Zn(1 - x)Fe2O4 were studied as a function of composition and particle size. Scanning electron microscopy images show particles synthesised by the aqueous co-precipitation method possess a broad size distribution (i.e. ~ 80-120 nm) with an average diameter of the order of 100 nm ± 20 nm and could be produced in high process yields of up to 25 g l - 1. In contrast, particles synthesised by the polyol-based co-precipitation method possess a narrower size distribution with an average diameter in the 30 nm ± 5 nm range but are limited to smaller yields of ~ 6 g l - 1. Furthermore, the polyol synthesis method was shown to control average particle size by varying the length of the glycol surfactant chain. Particles prepared by both methods are compared with respect to their phase purity, crystal structure, morphology, magnetic properties and microwave properties.

Daigle, A.; Modest, J.; Geiler, A. L.; Gillette, S.; Chen, Y.; Geiler, M.; Hu, B.; Kim, S.; Stopher, K.; Vittoria, C.; Harris, V. G.

2011-07-01

138

Comparative study of NiFe{sub 2?x}Al{sub x}O{sub 4} ferrite nanoparticles synthesized by chemical co-precipitation and sol–gel combustion techniques  

SciTech Connect

Graphical abstract: AFM images of NiFe{sub 2}O{sub 4} ferrite nanoparticles at room temperature synthesized by sol–gel technique. Highlights: ? Particle size reduces to less than 30 nm. ? DC electrical resistivity increases with substitution of Cr{sup 3+}. ? Dielectric constant decreases. -- Abstract: A series of aluminum substituted Ni-ferrite nanoparticles have been synthesized by chemical co-precipitation and sol–gel techniques. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), DC electrical resistivity and dielectric properties. Analysis of the X-ray diffraction pattern of all the samples confirmed the formation of spinel structure. The crystallite sizes remain within the range 25–41 ± 3 nm. FTIR measurements show two fundamental absorption bands, assigned to the vibration of tetrahedral and octahedral sites. DC electrical resistivity increases from 6.60 × 10{sup 7} to 6.9 × 10{sup 10} ? cm as the Al{sup 3+} concentration increases from 0.00 to 0.50. The dielectric constant and loss tangent decreases with increasing Al{sup 3+} concentration from 22 to 14, 0.354 to 0.27 respectively at 5 MHz for all the samples. Impedance measurements as a function of frequency (1 kHz–5 MHz) at room temperature further helped in analyzing the electrical properties of the prepared samples.

Gul, I.H., E-mail: iftikhar_qau@yahoo.com [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12 Islamabad (Pakistan); Pervaiz, Erum [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12 Islamabad (Pakistan)] [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12 Islamabad (Pakistan)

2012-06-15

139

Self-assembled organic-inorganic magnetic hybrid adsorbent ferrite based on cyclodextrin nanoparticles  

PubMed Central

Summary Organic–inorganic magnetic hybrid materials (MHMs) combine a nonmagnetic and a magnetic component by means of electrostatic interactions or covalent bonds, and notable features can be achieved. Herein, we describe an application of a self-assembled material based on ferrite associated with ?-cyclodextrin (Fe-Ni/Zn/?CD) at the nanoscale level. This MHM and pure ferrite (Fe-Ni/Zn) were used as an adsorbent system for Cr3+ and Cr2O7 2? ions in aqueous solutions. Prior to the adsorption studies, both ferrites were characterized in order to determine the particle size distribution, morphology and available binding sites on the surface of the materials. Microscopy analysis demonstrated that both ferrites present two different size domains, at the micro- and nanoscale level, with the latter being able to self-assemble into larger particles. Fe-Ni/Zn/?CD presented smaller particles and a more homogeneous particle size distribution. Higher porosity for this MHM compared to Fe-Ni/Zn was observed by Brunauer–Emmett–Teller isotherms and positron-annihilation-lifetime spectroscopy. Based on the pKa values, potentiometric titrations demonstrated the presence of ?CD in the inorganic matrix, indicating that the lamellar structures verified by transmission electronic microscopy can be associated with ?CD assembled structures. Colloidal stability was inferred as a function of time at different pH values, indicating the sedimentation rate as a function of pH. Zeta potential measurements identified an amphoteric behavior for the Fe-Ni/Zn/?CD, suggesting its better capability to remove ions (cations and anions) from aqueous solutions compared to that of Fe-Ni/Zn. PMID:23209524

Denadai, Angelo M L; De Sousa, Frederico B; Passos, Joel J; Guatimosim, Fernando C; Barbosa, Kirla D; Burgos, Ana E; de Oliveira, Fernando Castro; da Silva, Jeann C; Neves, Bernardo R A; Mohallem, Nelcy D S

2012-01-01

140

Characterization of oxide nanoparticles in Al-free and Al-containing oxide dispersion strengthened ferritic steels.  

PubMed

Oxide nanoparticles in oxide dispersion strengthened (ODS) ferritic steels with and without Al have been characterized by transmission electron microscopy. It is confirmed that most of the complex oxide particles consist of Y2TiO5 for 18Cr-ODS steel and YAlO3 or YAl5O12 for 18Cr5Al-ODS steel, respectivley. The addition of 5% Al in 18Cr-ODS steel leads to the formation of larger oxide particles and the reduction in their number density. For 18Cr-ODS steel, 87% of the oxide particles are coherent. The misfit strain of the coherent particles and a few semi-coherent particles is about 0.034 and 0.056, respectively. For 18Cr5Al-ODS steel, 75% of the oxide particles are semi-coherent, of which the misfit strain is 0.091 and 0.125, respectively. These results suggest that for the Al-containing ODS steel the Al addition accelerates the formation of semi-coherent oxide particles and its larger coherent and semi-coherent particles result in the larger misfit strain between the oxide particle and alloy matrix, indicating that the coherence of oxide nanoparticles in ODS steels is size-dependent. PMID:24205622

Lee, Jae Hoon; Kim, Jeoung Han

2013-09-01

141

[The preparation of NiFe2O4 composite nanoparticles and spectral properties].  

PubMed

The composite nanoparticles of Ni-ferrite with coated gelatin were prepared with the gel-microemulsion chemical tailoring method. The gelatin FeCl2 and NiCl2 were used to prepare gel, which was tailored to be particles in micellar of microemulsion, and the particles were reduced, compounded and nucleated. Surveying by XRD, TEM, IR and EDS showed that the particles formed were coated by gelatin protein and their mean sizes are in the range of 10-100 nm, and particle sizes are 3.3-4.6 nm. There are about 3-22 NiFe2O4 particles on each spheroid. The measurement of magnetic parameters indicated that the specific saturation magnetization was sigma(s) = 36.31 x 10(3)/4pi(A x m(-1) x g(-1)), coercivity was H(c) = 6750 A x m(-1), and residual magnetism B(r) = 4.39 x 10(3)/4pi(A x m(-1) x g(-1)). PMID:15768968

Zhu, Huai-wu; Zhang, Chao-ping

2004-01-01

142

Preparation, structural and morphological studies of Ni doped titania nanoparticles  

NASA Astrophysics Data System (ADS)

TiO2 nanoparticles doped with different weight percentages (4%, 8%, 12% and 16%) of nickel contents were prepared by a modified sol-gel method using Titanium tetra iso propoxide and nickel nitrate as precursors and 2-propanol as a solvent. X-ray diffraction studies show that the as prepared and annealed products show anatase structure with average particle sizes running between of 8 and 16 nm. FTIR results demonstrate the presence of strong chemical bonding at the interface of TiO2 nanoparticles. The optical properties of bare and doped samples were carried out using UV-DRS and photoluminescence measurements. The surface morphology and the element constitution of the nickel doped TiO2 nanoparticles were studied by scanning electron microscope attached with energy dispersive X-ray spectrometer arrangement. The non linear optical properties of the products were confirmed by Kurtz second harmonic generation (SHG) test and the output power generated by the nanoparticle was compared with that of potassium di hydrogen phosphate (KDP).

Rajamannan, B.; Mugundan, S.; Viruthagiri, G.; Shanmugam, N.; Gobi, R.; Praveen, P.

2014-07-01

143

Cobalt nanoparticles prepared in faujasite zeolites by borohydride reduction  

Microsoft Academic Search

Metallic cobalt nanoparticles have been prepared in the faujasite zeolite by the reduction of the Co2+-exchanged zeolite with sodium borohydride aqueous solutions. The influences of the temperature used for treating the Co2+-faujasite zeolite before reduction and the concentration of NaBH4 solution on the degree of reduction and the size of cobalt particles have been investigated. Although the treatment of the

Ye Wang; Hongli Wu; Qinghong Zhang; Qinghu Tang

2005-01-01

144

Frequency dependent dielectric measurements of Cd2+ doped Mn-Zn nano ferrites prepared by sol gel and coprecipitation methods  

NASA Astrophysics Data System (ADS)

Ferrite powders of Mn-Zn doped with Cd2+ (Mn0.5CdxZn0.5-xFe2O4) were prepared by the sol gel auto- combustion and coprecipitation methods. The effect of Cd2+ doping on the crystalline phase formation was investigated by X-ray diffraction which confirms the spinel structure of prepared samples. Crystallite size found to be lower for samples prepared by coprecipitation method. The samples prepared using coprecipitation, found to be denser as compared to sol gel method. SEM analysis confirmed the nano structure of the prepared samples. Dielectric properties were studied using impedance analyzer (20 Hz - 5 MHz) and RF material analyzer (1 MHz - 3 GHz) respectively. DC electrical measurements showed highly resistive nature of the prepared samples and values are high for samples prepared from sol gel method. Impedance spectroscopic analysis was carried out in the frequency range from 20 Hz to 5 MHz for the prepared samples, showing resistance of grain boundary is higher than grains. Impedance plane plots gave information about the resistive and reactive parts of impedance. The presence of semicircular arcs at lower frequency side, confirms that the high resistance of samples is due to increase in the number of grain boundaries in the nano synthesised samples.

Humaira, A.; Asghari, M.

2013-06-01

145

Structural and magnetic properties of Ni1-xZnxFe2O4 nano-crystalline ferrites prepared via novel chitosan method  

NASA Astrophysics Data System (ADS)

In the present study, nano-crystalline Ni1-xZnxFe2O4 ferrites (x = 0.0-1.0) were prepared via novel chitosan method. The prepared ferrites were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM) techniques. XRD revealed the formation of spinel single-phase structure for the samples with Zn-content more than 0.4. The crystallite sizes estimated using Scherer formula are in the range 34-45 nm. TEM images reflect the agglomeration characteristics of the prepared ferrites. FT-IR spectra show two prominent characteristic peaks of ferrites. VSM measurement suggests the validity of the entire method for preparation of ferrites with high magnetization. The saturation magnetization was found to increase up to x = 0.4 then gradually decrease while coercivity decreased with increasing Zn-content. These changes in the magnetic properties by the addition of Zn were discussed depending on the estimated cation distribution of the system and the magneto-crystalline anisotropy of the entire ions, respectively.

Gabal, M. A.; Kosa, S.; Al Mutairi, T. S.

2014-04-01

146

Preparation of Mn, Ni, Co ferrite highly porous silica nanocomposite aerogels by an urea-assisted sol-gel procedure.  

PubMed

The preparation of highly porous MnFe2O4-SiO2 and NiFe2O4-SiO2 nanocomposite aerogels with high purity and homogeneity was successfully achieved by a sol-gel procedure involving urea-assisted co-gelation of the precursor phases firstly applied for the synthesis of CoFe2O4-SiO2. This method allows fast gelation, giving rise to aerogels with 97% porosity. The structural, morphological and textural characterization as a function of thermal treatments was carried out by a multitechnique approach confirming that, as in the case of CoFe2O4-SiO2, the formation of single nanocrystals of manganese ferrite and nickel ferrite with spinel structure occurs after heating at 750 degrees C and is complete at 900 degrees C when the high porosity typical of aerogels is still retained. Thermogravimetric analysis (TG), differential thermal analysis (DTA), N2-physisorption at 77 K, powder X-ray diffraction (XRD), and transmission electron microscopy (TEM) indicate that the compositional homogeneity, crystallite size, thermal stability, and porosity are controlled by the sol-gel parameters of the preparation. PMID:20352749

Loche, Danilo; Casula, Maria F; Falqui, Andrea; Marras, Sergio; Corrias, Anna

2010-02-01

147

Effect of filler loading of nickel zinc ferrite on the tensile properties of PLA nanocomposites  

NASA Astrophysics Data System (ADS)

The mechanical strength of magnetic polymer nanocomposite (MPNC) of nickel zinc (NiZn) ferrite nanoparticles incorporated with polylactic acid (PLA) and liquid natural rubber (LNR) as compatibilizer is reported. The matrix was prepared from PLA and LNR in the ratio of 90:10. The MPNC were prepared at constant mixing temperature at 180°C, mixing time of 15 min. and mixing speed of 100 rpm. In order to achieve a good dispersion of NiZn ferrite in the matrix, firstly an ultrasonic treatment had been employed to mix the LNR and NiZn ferrite for 1 hour. The MPNC of PLA/LNR/NiZn ferrite then were prepared via Thermo Haake internal mixer using melt-blending method from different filler loading from 1-5 wt% NiZn ferrite. The result of tensile tests showed that as the filler loading increases the tensile strength also increases until an optimum value of filler loading was reached. The Young's modulus, tensile strength and elongation at break have also increased. The study proves that NiZn ferrite is excellent reinforcement filler in PLA matrix. Scanning electron micrograph (SEM) and energy dispersive X-ray spectroscopy (EDX) were meant to show the homogeneity dispersion of nanoparticles within the matrix and to confirm the elemental composition of NiZn ferrites-PLA/LNR nanocomposites respectively.

Shahdan, Dalila; Ahmad, Sahrim Hj

2013-05-01

148

Nickel-doped cobalt ferrite nanoparticles: efficient catalysts for the reduction of nitroaromatic compounds and photo-oxidative degradation of toxic dyes.  

PubMed

This study deals with the exploration of NixCo?-xFe?O? (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) ferrite nanoparticles as catalysts for reduction of 4-nitrophenol and photo-oxidative degradation of Rhodamine B. The ferrite samples with uniform size distribution were synthesized using the reverse micelle technique. The structural investigation was performed using powder X-ray diffraction, high-resolution transmission electron microscopy, energy dispersive X-ray and scanning tunneling microscopy. The spherical particles with ordered cubic spinel structure were found to have the crystallite size of 4-6 nm. Diffused UV-visible reflectance spectroscopy was employed to investigate the optical properties of the synthesized ferrite nanoparticles. The surface area calculated using BET method was found to be highest for Co?.?Ni?.?Fe?O? (154.02 m(2) g(-1)). Co?.?Ni?.?Fe?O? showed the best catalytic activity for reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 as reducing agent, whereas CoFe?O? was found to be catalytically inactive. The reduction reaction followed pseudo-first order kinetics. The effect of varying the concentration of catalyst and NaBH? on the reaction rates was also scrutinized. The photo-oxidative degradation of Rhodamine B, enhanced oxidation efficacy was observed with the introduction of Ni(2+) in to the cobalt ferrite lattice due to octahedral site preference of Ni(2+). Almost 99% degradation was achieved in 20 min using NiFe?O? nanoparticles as catalyst. PMID:24902783

Singh, Charanjit; Goyal, Ankita; Singhal, Sonal

2014-07-21

149

Preparation of Soft Manganese Ferrite and Inventional of its Magnetic Properties and Mn55 Nuclear Magnetic Resonance  

NASA Astrophysics Data System (ADS)

In this study, Mn-ferrite has been prepared with nominal formula of MnFe2O4, using the dry conventional ceramic method. The raw materials were Mobarakeh steel company modified domestic iron oxide and Merk manganese oxide. XRD patterns of the prepared samples show that they are single phase. Magnetic measurements have been performed on the toroidal samples sintered in different temperatures, using a hystograph unit MPG100D model. The results of measurements show that optimum formation pressures to obtain maximum relative magnetic permeability and hystersis. We report here the observation of the Mn55 nuclear magnetic resonance associated with the Mn2 + ion in the ferromagnetic spinel MnFe2O4 also.

Soleimani, R.; Soleimani, M.; Gheisari Godarzi, M.; Askari, A.

2011-08-01

150

Preparation of cobalt-zinc ferrite (Co{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) nanopowder via combustion method and investigation of its magnetic properties  

SciTech Connect

Research highlights: {yields} Cobalt-zinc ferrite was prepared by combustion method. {yields} Properties of the sample were characterized by several techniques. {yields} Curie temperature was determined to be 350 {sup o}C. -- Abstract: Cobalt-zinc ferrite (Co{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) was prepared by combustion method, using cobalt, zinc and iron nitrates. The crystallinity of the as-burnt powder was developed by annealing at 700 {sup o}C. Crystalline phase was investigated by XRD. Using Williamson-Hall method, the average crystallite sizes for nanoparticles were determined to be about 27 nm before and 37 nm after annealing, and residual stresses for annealed particles were omitted. The morphology of the annealed sample was investigated by TEM and the mean particle size was determined to be about 30 nm. The final stoichiometry of the sample after annealing showed good agreement with the initial stoichiometry using atomic absorption spectrometry. Magnetic properties of the annealed sample such as saturation magnetization, remanence magnetization, and coercivity measured at room temperature were 70 emu/g, 14 emu/g, and 270 Oe, respectively. The Curie temperature of the sample was determined to be 350 {sup o}C using AC-susceptibility technique.

Yousefi, M.H. [Department of Physics, Malek-Ashtar University of Technology, Shahinshahr, 83145-34177 (Iran, Islamic Republic of)] [Department of Physics, Malek-Ashtar University of Technology, Shahinshahr, 83145-34177 (Iran, Islamic Republic of); Manouchehri, S., E-mail: dez283@yahoo.com [Department of Physics, Malek-Ashtar University of Technology, Shahinshahr, 83145-34177 (Iran, Islamic Republic of); Department of Physics, Faculty of Science, The University of Isfahan, Esfahan 81746-73441 (Iran, Islamic Republic of); Arab, A. [Department of Physics, Malek-Ashtar University of Technology, Shahinshahr, 83145-34177 (Iran, Islamic Republic of)] [Department of Physics, Malek-Ashtar University of Technology, Shahinshahr, 83145-34177 (Iran, Islamic Republic of); Mozaffari, M. [Department of Physics, Faculty of Science, The University of Isfahan, Esfahan 81746-73441 (Iran, Islamic Republic of) [Department of Physics, Faculty of Science, The University of Isfahan, Esfahan 81746-73441 (Iran, Islamic Republic of); Physics Department, Razi University, Taghbostah, Kermanshah (Iran, Islamic Republic of); Amiri, Gh. R. [Department of Physics, Malek-Ashtar University of Technology, Shahinshahr, 83145-34177 (Iran, Islamic Republic of) [Department of Physics, Malek-Ashtar University of Technology, Shahinshahr, 83145-34177 (Iran, Islamic Republic of); Department of Plasma Physics, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Amighian, J. [Islamic Azad University, Najafabad Branch, Najafabad (Iran, Islamic Republic of)] [Islamic Azad University, Najafabad Branch, Najafabad (Iran, Islamic Republic of)

2010-12-15

151

Preparation and Properties of FeCo Nanoparticles  

SciTech Connect

Fe-Co nanoparticles were prepared from the binary Fe-Co oxalate. The formation of FeCo metallic phase begun at 290 deg. C as determined from the X-ray diffraction patterns recorded during heating of the oxalate sample in hydrogen atmosphere. The reduction finished at 500 deg. C by formation of bcc FeCo phase with a mean particle size of about 50 nm. Analysis of the Moessbauer spectra shows that the ferromagnetic FeCo phase is represented by two sextets corresponding to interiors and surfaces of the nanoparticles. In addition, a weak paramagnetic component, represented by the doublet, was observed which was ascribed to fine particles in a superparamagnetic state. TEM images have shown conglomerates of particles with the composition of about 50 at. % Fe and 50 at. % Co.

Zabransky, K.; David, B.; Pizurova, N.; Schneeweiss, O. [Institute of Physics of Materials, Academy of Sciences of Czech Republic, v.v.i., Zizkova 22, 61662 Brno (Czech Republic); Zboril, R.; Maslan, M. [Centre for Nanomaterial Research, Faculty of Science, Palacky University, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic)

2010-07-13

152

Preparation and characterization of Au nanoparticles capped with mercaptocarboranyl clusters.  

PubMed

The preparation of 3-4 nm and 10 nm gold nanoparticles capped with neutral carborane-based mercaptocarboranes, via two different preparative routes, is reported. The resulting boron-enriched nanomaterials exhibit complete dispersibility in water, opening the way for the use of these monolayer protected clusters (MPCs) in medical applications, such as boron neutron capture therapy (BNCT). These newly prepared MPCs have been characterized by FTIR, (1)H and (11)B NMR spectroscopy, UV-visible, centrifugal particle sizing (CPS), and, in some cases, inductively coupled plasma atomic emission spectrometry (ICP-AES). Water dispersibility exhibited by these MPCs allowed the study of the cellular uptake by HeLa cells. PMID:24301037

Cioran, Ana M; Teixidor, Francesc; Krpeti?, Željka; Brust, Mathias; Viñas, Clara

2014-04-01

153

Y 2O 3 nano-particle formation in ODS ferritic steels by Y and O dual ion-implantation  

NASA Astrophysics Data System (ADS)

For basic understanding of how to produce a homogeneous distribution of nano-scale oxide particles, we have applied dual ion-implantation to make a super-saturation of oxide-forming elements. Y + and O + ions were implanted into ferritic alloys at room temperature. Both in situ annealing in an electron microscope for thin samples and conventional annealing for bulk samples were carried out at 300-1300 K. Nano-particles of Y 2O 3 precipitated during annealing, where the starting temperatures for the nucleation and growth depended on the annealing methods. In thin specimens the growth and nucleation of Y 2O 3 started at 573 and 613 K. In bulk specimens, the growth and nucleation shifted to higher temperatures. Compared with conventional Mechanical Alloying, it is concluded that dual ion-implantation can produce much finer distributions of nano-scale oxides. In order to explain these results, we emphasize the roles of super-saturated elements and lattice defects.

Sakuma, D.; Yamashita, S.; Oka, K.; Ohnuki, S.; Rehn, L. E.; Wakai, E.

2004-08-01

154

Structural and magnetic properties of dispersed nickel ferrite nanoparticles synthesized through thermal decomposition route  

NASA Astrophysics Data System (ADS)

Dispersed NiFe2O4 nanoparticles are synthesized through thermal decomposition of mixed-metal (Ni2+Fe3+)-oleate complex in the presence of high boiling point organic solvent 1-octadecene with oleic acid, by tuning the mixed-metal (Ni2+Fe3+)-oleate complex precursor and the temperature. Oleic acid is used as a surfactant, capped on the surface of the particles, which assists the particles to disperse in hexane. The as-synthesized NiFe2O4 nanoparticles have a cubic spinel structure as characterized by x-ray diffraction. The ferrimagnetic nature of these nanoparticles is conformed from the field dependent room temperature magnetization curves measured using vibrating sample magnetometer. The saturation magnetization of these nanoparticles strongly depends on the particle size which can be tuned by the mixed-metal (Ni2+Fe3+)-oleate complex precursor concentration and the synthesis temperature. Transmission electron microscope images show that the particles are nearly monodispersed at high synthesis temperature.

Behera, Bhaskar Chandra; Venkata, Ravindra A.; Srivastava, Chandan; Padhan, Prahallad

2013-02-01

155

Zinc ferrite nanoparticles as MRI contrast agentsw Carlos Ba rcena,a  

E-print Network

Feridexs . Magnetic resonance imaging (MRI) is a powerful clinical imaging technique for the non on acquiring biological specificity of SPIO by surface modifications,2,3 it still remains an open challenge of Zn-SPIO nanoparticles is the reduced toxicity of Zn over Mn. For example, the Food and Drug

Gao, Jinming

156

Evaluation of iron-cobalt\\/ferrite core-shell nanoparticles for cancer thermotherapy  

Microsoft Academic Search

Magnetic nanoparticles (MNPs) offer promise for local hyperthermia or thermoablative cancer therapy. Magnetic hyperthermia uses MNPs to heat cancerous regions in an rf field. Metallic MNPs have larger magnetic moments than iron oxides, allowing similar heating at lower concentrations. By tuning the magnetic anisotropy in alloys, the heating rate at a particular particle size can be optimized. Fe–Co core-shell MNPs

A. H. Habib; C. L. Ondeck; P. Chaudhary; M. R. Bockstaller; M. E. McHenry

2008-01-01

157

Evaluation of iron-cobalt\\/ferrite core-shell nanoparticles for cancer thermotherapy  

Microsoft Academic Search

Magnetic nanoparticles (MNPs) offer promise for local hyperthermia or thermoablative cancer therapy. Magnetic hyperthermia uses MNPs to heat cancerous regions in an rf field. Metallic MNPs have larger magnetic moments than iron oxides, allowing similar heating at lower concentrations. By tuning the magnetic anisotropy in alloys, the heating rate at a particular particle size can be optimized. Fe-Co core-shell MNPs

A. H. Habib; C. L. Ondeck; P. Chaudhary; M. R. Bockstaller; M. E. McHenry

2008-01-01

158

Field dependent transition to the non-linear regime in magnetic hyperthermia experiments: Comparison between maghemite, copper, zinc, nickel and cobalt ferrite nanoparticles of similar sizes  

NASA Astrophysics Data System (ADS)

Further advances in magnetic hyperthermia might be limited by biological constraints, such as using sufficiently low frequencies and low field amplitudes to inhibit harmful eddy currents inside the patient's body. These incite the need to optimize the heating efficiency of the nanoparticles, referred to as the specific absorption rate (SAR). Among the several properties currently under research, one of particular importance is the transition from the linear to the non-linear regime that takes place as the field amplitude is increased, an aspect where the magnetic anisotropy is expected to play a fundamental role. In this paper we investigate the heating properties of cobalt ferrite and maghemite nanoparticles under the influence of a 500 kHz sinusoidal magnetic field with varying amplitude, up to 134 Oe. The particles were characterized by TEM, XRD, FMR and VSM, from which most relevant morphological, structural and magnetic properties were inferred. Both materials have similar size distributions and saturation magnetization, but strikingly different magnetic anisotropies. From magnetic hyperthermia experiments we found that, while at low fields maghemite is the best nanomaterial for hyperthermia applications, above a critical field, close to the transition from the linear to the non-linear regime, cobalt ferrite becomes more efficient. The results were also analyzed with respect to the energy conversion efficiency and compared with dynamic hysteresis simulations. Additional analysis with nickel, zinc and copper-ferrite nanoparticles of similar sizes confirmed the importance of the magnetic anisotropy and the damping factor. Further, the analysis of the characterization parameters suggested core-shell nanostructures, probably due to a surface passivation process during the nanoparticle synthesis. Finally, we discussed the effect of particle-particle interactions and its consequences, in particular regarding discrepancies between estimated parameters and expected theoretical predictions.

Verde, E. L.; Landi, G. T.; Carrião, M. S.; Drummond, A. L.; Gomes, J. A.; Vieira, E. D.; Sousa, M. H.; Bakuzis, A. F.

2012-09-01

159

Preparation of poly(?-lactide-co-glycolide) nanoparticles by modified spontaneous emulsification solvent diffusion method  

Microsoft Academic Search

Purpose: The objectives of this study were to establish a new preparation method for poly(DL-lactide-co-glycolide) (PLGA) nanoparticles by modifying the spontaneous emulsification solvent diffusion (SESD) method and to elucidate the mechanism of nanoparticle formation on the basis of the phase separation principle of PLGA and poly(vinyl alcohol) (PVA) in the preparation system. Methods: PLGA nanoparticles were prepared by the modified-SESD

Hideki Murakami; Masao Kobayashi; Hirofumi Takeuchi; Yoshiaki Kawashima

1999-01-01

160

Self-assembled mesoporous Co and Ni-ferrite spherical clusters consisting of spinel nanocrystals prepared using a template-free approach.  

PubMed

Based on a self-assembly strategy, spherical mesoporous cobalt and nickel ferrite nanocrystal clusters with a large surface area and narrow size distribution were successfully synthesized for the first time via a template-free solvothermal process in ethylene glycol and subsequent heat treatment. In this work, the mesopores in the ferrite clusters were derived mainly from interior voids between aggregated primary nanoparticles (with crystallite size of less than 7 nm) and disordered particle packing domains. The concentration of sodium acetate is shown herein to play a crucial role in the formation of mesoporous ferrite spherical clusters. These ferrite clusters were characterized in detail using wide-angle X-ray diffraction, thermogravimetric-differential thermal analysis, (57)Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, standard and high-resolution transmission electron microscopy, and other techniques. The results confirmed the formation of both pure-phase ferrite clusters with highly crystalline spinel structure, uniform size (about 160 nm) and spherical morphology, and worm-like mesopore structures. The BET specific surface areas and mean pore sizes of the mesoporous Co and Ni-ferrite clusters were as high as 160 m(2) g(-1) and 182 m(2) g(-1), and 7.91 nm and 6.87 nm, respectively. A model for the formation of the spherical clusters in our system is proposed on the basis of the results. The magnetic properties of both samples were investigated at 300 K, and it was found that these materials are superparamagnetic. PMID:21904731

Yu, Byong Yong; Kwak, Seung-Yeop

2011-10-21

161

Pd on amine-terminated ferrite nanoparticles: a complete magnetically recoverable facile catalyst for hydrogenation reactions.  

PubMed

[structure: see text]. The present communication reports a facile route for Pd(0) immobilization on the surface of amine-terminated Fe3O4 and NiFe2O4 nanoparticles for a series of hydrogenation reactions. The catalysts are completely recoverable with the simple application of an external magnetic field, and the efficiency of the catalyst remains unaltered even after 10 repeated cycles for each of the reactions. PMID:17323965

Guin, Debanjan; Baruwati, Babita; Manorama, Sunkara V

2007-03-29

162

Structural refinement analysis of bulk Zn-ferrite obtained from sintering of its nanoparticles  

NASA Astrophysics Data System (ADS)

The structural refinements were performed on the samples sintered from ZnFe2O4 nanoparticles of average crystallite size (d) ranged 2 to 12 nm. The X-ray diffraction (XRD) patterns showed single phase spinel structure for all sintered samples except the sample sintered from the d = 2 nm particles. This sample showed minor impurity phase of R-3C space group.

Thirupathi, G.; Singh, R.

2013-02-01

163

Magnetic and optical properties of ionic ferrofluids based on nickel ferrite nanoparticles  

Microsoft Academic Search

New ionic ferrofluids containing NiFe2O4 nanoparticles of size <=10 nm are investigated. The crystalline structure of the particles is probed by transmission electron microscopy and x-ray scattering. Static magnetization and field-induced birefringence measurements are performed on three samples differing by particle volume fraction. Cross analyzing of the results of those two types of macroscopic tests completely rejects a simple single-domain

E. Hasmonay; J. Depeyrot; M. H. Sousa; F. A. Tourinho; J.-C. Bacri; R. Perzynski; Yu. L. Raikher; I. Rosenman

2000-01-01

164

Ciprofloxacin Loaded Alginate\\/Chitosan and Solid Lipid Nanoparticles, Preparation and Characterization  

Microsoft Academic Search

The aim of the present study was to develop controlled drug delivery systems based on nanotechnology. Two different nanocarriers were selected, chitosan- alginate nanoparticles as hydrophilic and solid lipid nanoparticles as lipophilic carriers. Nanoparticles were prepared and characterized by evaluating particle size, zeta potential, SEM pictures, DSC thermograms, percentage of drug loading efficiency and drug release profile. The particle size

Solmaz Ghaffari; Jaleh Varshosaz; Ismaeil Haririan; Mohammad Reza Khoshayand; Shirzad Azarmi; Taraneh Gazori

2011-01-01

165

Ciprofloxacin Loaded Alginate\\/Chitosan and Solid Lipid Nanoparticles, Preparation, and Characterization  

Microsoft Academic Search

The aim of the present study was to develop controlled drug delivery systems based on nanotechnology. Two different nanocarriers were selected, chitosan-alginate nanoparticles as hydrophilic and solid lipid nanoparticles as lipophilic carriers. Nanoparticles were prepared and characterized by evaluating particle size, zeta potential, SEM pictures, DSC thermograms, percentage of drug loading efficiency, and drug release profile. The particle size of

Solmaz Ghaffari; Jaleh Varshosaz; Ismaeil Haririan; Mohammad Reza Khoshayand; Shirzad Azarmi; Taraneh Gazori

2012-01-01

166

Albumin nanoparticles for the delivery of gabapentin: preparation, characterization and pharmacodynamic studies.  

PubMed

The study was aimed to prepare and evaluate gabapentin loaded albumin nanoparticles and to find out their effectiveness in treating epilepsy. Albumin nanoparticles of gabapentin were prepared by pH-coacervation method. The drug was administered into animals as free drug, gabapentin bound with nanoparticles, and gabapentin bound with nanoparticles coated with polysorbate 80. The polysorbate 80 coated nanoparticles increased the gabapentin concentration in the brain about 3 fold in comparison with the free drug. Moreover, the polysorbate 80 coated nanoparticles significantly reduced the duration of all phases of convulsion in both maximal electroshock induced and pentylenetetrazole induced convulsion models in comparison with free drug and drug bound with nanoparticle formulations, which indicates the ability of polysorbate 80 coated nanoparticles to enhance the gabapentin concentration in the brain. PMID:24999053

Wilson, Barnabas; Lavanya, Y; Priyadarshini, S R B; Ramasamy, Muthu; Jenita, Josephine Leno

2014-10-01

167

Preparation and application of magnetic Fe 3O 4 nanoparticles for wastewater purification  

Microsoft Academic Search

Fe3O4 magnetic nanoparticles with different average sizes were synthesized and structural characterizations showed that the three kinds of nanoparticles had different sizes, i.e., an average particle size of 8nm, 12nm and 35nm was observed for the nanoparticles prepared with the co-precipitation method, the co-precipitation combining a surface decoration process, and the polyol process, respectively. The synthesized Fe3O4 nanoparticles with different

Y. F. Shen; J. Tang; Z. H. Nie; Y. D. Wang; Y. Ren; L. Zuo

2009-01-01

168

Preparation of Polymer-Coated Functionalized Ferrimagnetic Iron Oxide Nanoparticles*  

E-print Network

A simple chemical method to synthesize PMAA coated maghemite nanoparticles is described. Monomer methacrylic acid molecules were absorbed onto the synthesized ferrimagnetic nanoparticles followed by polymerization. The ...

Yu, Shi

169

Preparation of bio-compatible boron nanoparticles and novel mesoporous silica nanoparticles for bio-applications  

NASA Astrophysics Data System (ADS)

This dissertation presents the synthesis and characterization of several novel inorganic and hybrid nanoparticles, including the bio-compatible boron nanoparticles (BNPs) for boron neutron capture therapy (BNCT), tannic acid-templated mesoporous silica nanoparticles and degradable bridged silsesquioxane silica nanoparticles. Chapter 1 provides background information of BNCT and reviews the development of design and synthesizing silica nanoparticles and the study of silica material degradability. Chapter 2 describes the preparation and characterization of dopamine modified BNPs and the preliminary cell study of them. The BNPs were first produced via ball milling, with fatty acid on the surface to stabilize the combustible boron elements. This chapter will mainly focus on the ligand-exchange strategy, in which the fatty acids were replaced by non-toxic dopamines in a facile one-pot reaction. The dopamine-coated BNPs (DA-BNPs) revealed good water dispersibility and low cytotoxicity. Chapter 3 describes the synthesis of tannic acid template mesoporous silica nanoparticles (TA-TEOS SiNPs) and their application to immobilize proteins. The monodispersed TA SiNPs with uniform pore size up to approximately 13 nm were produced by utilizing tannic acid as a molecular template. We studied the influence of TA concentration and reaction time on the morphology and pore size of the particles. Furthermore, the TA-TEOS particles could subsequently be modified with amine groups allowing them to be capable of incorporating imaging ligands and other guest molecules. The ability of the TA-TEOS particles to store biomolecules was preliminarily assessed with three proteins of different charge characteristics and dimensions. The immobilization of malic dehydrogenase on TA-TEOS enhanced the stability of the enzyme at room temperature. Chapter 4 details the synthesis of several bridged silsesquioxanes and the preparation of degradable hybrid SiNPs via co-condensation of bridged silsesquioxanes with tetraethoxysilane. In vivo studies show that the solid SiNPs accumulate in many organs due to the lack of degradability. The aim of our work is to address this shortcoming by producing novel degradable SiNPs. Bridged silsesquioxanes were used as the precursors of the particles, and upon cleavage of the carbamate groups when brought into contact with aqueous media, the particles degraded into porous structures.

Gao, Zhe

170

Preparation and evaluation of lectin-conjugated PLGA nanoparticles for oral delivery of thymopentin  

Microsoft Academic Search

The purpose of this study was to design and evaluate lectin-conjugated PLGA nanoparticles for oral delivery of thymopentin. Thymopentin loaded PLGA nanoparticles (TP5–NPs) were prepared by a double emulsion-solvent evaporation technique. Novel WGA–PLGA conjugates were synthesized by coupling the amino groups of wheat germ agglutinin (WGA) to the carbodiimide-activated carboxylic groups of PLGA, and were incorporated into nanoparticles preparation to

YaShu Yin; DaWei Chen; MingXi Qiao; Zhe Lu; HaiYang Hu

2006-01-01

171

Silver confined within zeolite EMT nanoparticles: preparation and antibacterial properties  

NASA Astrophysics Data System (ADS)

The preparation of pure zeolite nanocrystals (EMT-type framework) and their silver ion-exchanged (Ag+-EMT) and reduced silver (Ag0-EMT) forms is reported. The template-free zeolite nanocrystals are stabilized in water suspensions and used directly for silver ion-exchange and subsequent chemical reduction under microwave irradiation. The high porosity, low Si/Al ratio, high concentration of sodium and ultrasmall crystal size of the EMT-type zeolite permitted the introduction of a high amount of silver using short ion-exchange times in the range of 2-6 h. The killing efficacy of pure EMT, Ag+-EMT and Ag0-EMT against Escherichia coli was studied semi-quantitatively. The antibacterial activity increased with increasing Ag content for both types of samples (Ag+-EMT and Ag0-EMT). The Ag0-EMT samples show slightly enhanced antimicrobial efficacy compared to that of Ag+-EMT, however, the differences are not substantial and the preparation of Ag nanoparticles is not viable considering the complexity of preparation steps.The preparation of pure zeolite nanocrystals (EMT-type framework) and their silver ion-exchanged (Ag+-EMT) and reduced silver (Ag0-EMT) forms is reported. The template-free zeolite nanocrystals are stabilized in water suspensions and used directly for silver ion-exchange and subsequent chemical reduction under microwave irradiation. The high porosity, low Si/Al ratio, high concentration of sodium and ultrasmall crystal size of the EMT-type zeolite permitted the introduction of a high amount of silver using short ion-exchange times in the range of 2-6 h. The killing efficacy of pure EMT, Ag+-EMT and Ag0-EMT against Escherichia coli was studied semi-quantitatively. The antibacterial activity increased with increasing Ag content for both types of samples (Ag+-EMT and Ag0-EMT). The Ag0-EMT samples show slightly enhanced antimicrobial efficacy compared to that of Ag+-EMT, however, the differences are not substantial and the preparation of Ag nanoparticles is not viable considering the complexity of preparation steps. Electronic supplementary information (ESI) available: Zeta potential data of Ag-EMT suspensions, pore-size distributions and antibacterial data for Ag-EMT 2 h samples. See DOI: 10.1039/c4nr03169e

Dong, B.; Belkhair, S.; Zaarour, M.; Fisher, L.; Verran, J.; Tosheva, L.; Retoux, R.; Gilson, J.-P.; Mintova, S.

2014-08-01

172

Preparation and up-conversion luminescence of 8 nm rare-earth doped fluoride nanoparticles  

E-print Network

Preparation and up-conversion luminescence of 8 nm rare-earth doped fluoride nanoparticles V.Tikhomirov@fys.kuleuven.be, Christiane.Walrand@chem.kuleuven.be Abstract: Free-standing, 8 nm diameter, rare-earth doped nanoparticles Re10Pb25F65 have been prepared, where Re stands for either single rare-earth ion, such as Er3+ , Yb3

Moshchalkov, Victor V.

173

Preparation of Monodispersed Fe-Mo Nanoparticles as the Catalyst for CVD Synthesis of Carbon Nanotubes  

E-print Network

27708 Yongqian Wang and Zhong Lin Wang School of Materials Science and Engineering, Georgia Institute Received December 19, 2000 Uniform iron-molybdenum nanoparticles were prepared by thermal decomposition/amine of the protective agents on the sizes of the produced nanoparticles were systematically studied. The prepared nano

Wang, Zhong L.

174

Electrochemical and Structural Characterizations of InSb Nanoparticles Prepared Using a Sodium Naphthalenide  

E-print Network

Electrochemical and Structural Characterizations of InSb Nanoparticles Prepared Using a Sodium, Ansan, 426-791, South Korea InSb nanoparticles with a mean particle size of 10 nm prepared and TEM results revealed the progressive formation of extruded In from InSb, followed by the formation

Cho, Jaephil

175

Enrichment of magnetic alignment stimulated by {gamma}-radiation in core-shell type nanoparticle Mn-Zn ferrite  

SciTech Connect

Core shell type nanoparticle Mn{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} systems with x=0.55, 0.65 and 0.75 were prepared using autocombustion method. The systems were characterized using tools like XRD and IR for structure confirmation. Magnetic parameter measurements like Saturation magnetization and coercivity were obtained from hysteresis loop which exhibited a symmetry shift due to core shell nature of the nanoparticles. Nanoparticles of particle size between 21.2nm to 25.7nm were found to show 20 percent shrinkage after being radiated by the {gamma}-radiation. This is due to variation in the cation distribution which also affects the cell volume of the cubic cell. Lattice constant reduction observed is reflected in the magnetic properties of the samples. A considerable hike in the saturation magnetization of the samples was observed due to enrichment of magnetic alignment in the magnetic core of the particles. Samples under investigation were irradiated with gamma radiation from Co{sup 60} source for different time intervals.

Naik, P. P.; Tangsali, R. B. [Department of Physics, Goa University, Taleigao Plateau, Goa-403206 (India); Sonaye, B.; Sugur, S. [Goa Medical College, Bambolim, Goa (India)

2013-02-05

176

Synthesis of epoxy ferrite nanocomposites in supercritical carbon dioxide  

Microsoft Academic Search

A series of epoxy ferrite nanocomposites (EFNCs) was synthesised through dispersing ferrite nanoparticles (5.0 phr, parts per hundred of resin) into diglycidylether of bisphenol A (0.1 mol) in supercritical carbon dioxide at 85 ± 1°C, 1600 psi over 1 h followed by curing with triethylene tetramine (15 phr) at 40 ± 1°C. For this purpose, ferrite nanoparticles were synthesised through

M. G. H. Zaidi; P. L. Sah; S. Alam; A. K. Rai

2009-01-01

177

Evaluation of iron-cobalt/ferrite core-shell nanoparticles for cancer thermotherapy  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles (MNPs) offer promise for local hyperthermia or thermoablative cancer therapy. Magnetic hyperthermia uses MNPs to heat cancerous regions in an rf field. Metallic MNPs have larger magnetic moments than iron oxides, allowing similar heating at lower concentrations. By tuning the magnetic anisotropy in alloys, the heating rate at a particular particle size can be optimized. Fe-Co core-shell MNPs have protective CoFe2O4 shell which prevents oxidation. The oxide coating also aids in functionalization and improves biocompatibility of the MNPs. We predict the specific loss power (SLP) for FeCo (SLP ˜450W /g) at biocompatible fields to be significantly larger in comparision to oxide materials. The anisotropy of Fe-Co MNPs may be tuned by composition and/or shape variation to achieve the maximum SLP at a desired particle size.

Habib, A. H.; Ondeck, C. L.; Chaudhary, P.; Bockstaller, M. R.; McHenry, M. E.

2008-04-01

178

Preparation of ZnO nanoparticles and characteristics of dye-sensitized solar cells based on nanoparticles film  

NASA Astrophysics Data System (ADS)

ZnO nanoparticles were synthesized by hydrolization method and the effects of zinc nitrate concentration and reaction temperature on the resulted particle properties were studied. The transmission of the as-prepared and calcined films and their optical band gaps are measured and calculated respectively. Furthermore, as an application of the ZnO nanoparticles film, dye-sensitized solar cells based on it were successfully fabricated and the cell performances were characterized. The short circuit current for ZnO nanoparticles film DSSCs is 1.35 mA cm -2, which indicates good value of the prepared film using this technique.

Liu, Zhifeng; Liu, Chengcheng; Ya, Jing; E, Lei

2010-01-01

179

Preparation and adsorption of refined polyelectrolyte complex nanoparticles.  

PubMed

We report on bulk and surface properties of centrifuged nonstoichiometric polyelectrolyte complex (PEC) dispersions. PECs were prepared by mixing poly(diallyldimethylammonium chloride) (PDADMAC) and sodium poly(maleic acid-co-alpha-methylstyrene) (PMA-MS) at the monomolar mixing ratio of 0.6 and polymer concentration >/=1 mmol/l. Centrifugation of initial PEC dispersions revealed three phases: supernatant (SUP), coacervate (COAC), and an insoluble precipitate. Mass, turbidity, particle hydrodynamic radii (R(h)), and the titratable charge amount were determined for those phases. The turbid COAC phase consisted of 200-nm nanoparticles and carried 60% of the polymer mass and 20% of the titratable charge amount of the initial PEC dispersion. The SUP phase showed no turbidity and no such nanoparticles, but carried 80% of the initial titratable charge amount, presumably caused by excess polycations. Furthermore, linear dependences of turbidity and R(h) on COAC concentration was observed. COAC adsorption was studied at polyelectrolyte multilayer (PEM) modified silicon surfaces in dependence on both adsorption time and concentration using attenuated total-reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The adsorption data were fitted by the simple Langmuir model. Comparison of COAC particles and polystyrene latices revealed similar adsorption features. SEM and AFM measurements resulted in hemispherically shaped adsorbed COAC particles with coverages >/=25%, whose calculated volumes correlated well with those in dispersion obtained by PCS. PMID:14757079

Reihs, T; Müller, M; Lunkwitz, K

2004-03-01

180

Nanoparticles containing ketoprofen and acrylic polymers prepared by an aerosol flow reactor method.  

PubMed

The purpose of this study was to outline the effects of interactions between a model drug and various acrylic polymers on the physical properties of nanoparticles prepared by an aerosol flow reactor method. The amount of model drug, ketoprofen, in the nanoparticles was varied, and the nanoparticles were analyzed for particle size distribution, particle morphology, thermal properties, IR spectroscopy, and drug release. The nanoparticles produced were spherical, amorphous, and had a matrix-type structure. Ketoprofen crystallization was observed when the amount of drug in Eudragit L nanoparticles was more than 33% (wt/wt). For Eudragit E and Eudragit RS nanoparticles, the drug acted as an effective plasticizer resulting in lowering of the glass transition of the polymer. Two factors affected the preparation of nanoparticles by the aerosol flow reactor method, namely, the solubility of the drug in the polymer matrix and the thermal properties of the resulting drug-polymer matrix. PMID:15760065

Eerikäinen, Hannele; Peltonen, Leena; Raula, Janne; Hirvonen, Jouni; Kauppinen, Esko I

2004-01-01

181

Silver confined within zeolite EMT nanoparticles: preparation and antibacterial properties.  

PubMed

The preparation of pure zeolite nanocrystals (EMT-type framework) and their silver ion-exchanged (Ag(+)-EMT) and reduced silver (Ag(0)-EMT) forms is reported. The template-free zeolite nanocrystals are stabilized in water suspensions and used directly for silver ion-exchange and subsequent chemical reduction under microwave irradiation. The high porosity, low Si/Al ratio, high concentration of sodium and ultrasmall crystal size of the EMT-type zeolite permitted the introduction of a high amount of silver using short ion-exchange times in the range of 2-6 h. The killing efficacy of pure EMT, Ag(+)-EMT and Ag(0)-EMT against Escherichia coli was studied semi-quantitatively. The antibacterial activity increased with increasing Ag content for both types of samples (Ag(+)-EMT and Ag(0)-EMT). The Ag(0)-EMT samples show slightly enhanced antimicrobial efficacy compared to that of Ag(+)-EMT, however, the differences are not substantial and the preparation of Ag nanoparticles is not viable considering the complexity of preparation steps. PMID:25117582

Dong, B; Belkhair, S; Zaarour, M; Fisher, L; Verran, J; Tosheva, L; Retoux, R; Gilson, J-P; Mintova, S

2014-09-21

182

The effects of particle size and surface coating on the cytotoxicity of nickel ferrite.  

PubMed

The safety and toxicity of nanoparticles are of growing concern despite their significant scientific interests and promising potentials in many applications. The properties of nanoparticles depend not only on the size but also the structure, microstructure and surface coating. These in turn are controlled by the synthesis and processing conditions. The dependence of cytotoxicity on particle size and on the presence of oleic acid as surfactant on nickel ferrite particles were investigated in vitro using the Neuro-2A cell line as a model. For nickel ferrite particles without oleic acid prepared by ball milling, cytotoxicity was independent of particle size within the given mass concentrations and surface areas accessible to the cells. For nickel ferrite particles coated with oleic acid prepared by the polyol method, the cytotoxicity significantly increased when one or two layers of oleic acid were deposited. Large particles (150+/-50 nm diameter) showed a higher cytotoxicity than smaller particles (10+/-3 nm diameter). PMID:15949547

Yin, H; Too, H P; Chow, G M

2005-10-01

183

Preparation and characterization of ultra-hydrophobic calcium carbonate nanoparticles  

NASA Astrophysics Data System (ADS)

Anionic surfactants based on fatty acids are usually used to modify the particle surface properties of CaCO3 with the aim to enhance its dispersion and compatibility with polymer matrices. In this study sodium oleate was used for the preparation of ultrahydrophobic CaCO3 nanoparticles using a wet carbonation route. The effect of sodium oleate on the characteristics, particle size, morphology, surface potential, thermal decomposition and hydrophobicity of CaCO3, was investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), Zeta potential, thermogravimetric analysis (TGA) and water contact angle measurement (WCA). The results showed that the addition of 2 wt% sodium oleate helps in reducing the particle size from 2 ?m length scalenohedral particles to 45 nm rhombohedral particles and modifying of the hydrophobic property of CaCO3.

Barhoum, A.; El-Sheikh, S. M.; Morsy, F.; El-Sherbiny, S.; Reniers, F.; Dufour, T.; Delplancke, M. P.; Van Assche, G.; Rahier, H.

2014-08-01

184

Effect of Ti-containing inclusions on the nucleation of acicular ferrite and mechanical properties of multipass weld metals.  

PubMed

In the present study, the influence of Ti-containing inclusions on the development of acicular ferrite microstructure and mechanical properties in the multipass weld metals has been studied. Shielded metal arc weld deposits were prepared by varying titanium content in the range of 0.003-0.021%. The variation in the titanium content was obtained by the addition of different amounts of titanium oxide nanoparticles to the electrode coating. The dispersion of titanium oxide nanoparticles, composition of inclusions, microstructural analysis, tensile properties and Charpy impact toughness were evaluated. As the amount of Ti-containing inclusions in the weld metal was increased, the microstructure of the weld metal was changed from the grain boundary allotriomorphic ferrite structure to acicular ferrite with the intragranular nucleation of ferrite on the Ti-containing inclusions, and the mechanical properties were improved. This improvement is attributable to the increased percentage of acicular ferrite due to the uniform dispersion of Ti-containing inclusions and the pinning force of oxide nanoparticles against the growth of allotriomorphic ferrite and Widmanstätten ferrite from the austenite grain boundaries. PMID:23238108

Fattahi, M; Nabhani, N; Hosseini, M; Arabian, N; Rahimi, E

2013-02-01

185

Preparation and Evaluation of Montelukast Sodium Loaded Solid Lipid Nanoparticles  

PubMed Central

Solid lipid nanoparticles (SLNs) are an alternative carrier system used to load the drug for targeting, to improve the bioavailability by increasing its solubility, and protecting the drug from presystemic metabolism. The avoidance of presystemic metabolism is due to the nano-metric size range, so that the liver cannot uptake the drug from the delivery system and is not metabolized by the liver. Montelukast sodium is an anti-asthmatic drug, because of its poor oral bioavailability, presystemic metabolism, and decreased half-life; it was chosen to formulate as the solid lipid nanoparticle (SLN) system by hot homogenization followed by an ultrasonication method, to overcome the above. Compritol ATO 888, stearic acid, and glyceryl monostearate were used as a lipid matrix and polyvinyl alcohol as a surfactant. The prepared formulations have been evaluated for entrapment efficiency, drug content, in vitro drug release, particle size analysis, scanning electron microscopy, Fourier transform-infrared studies (FT-IR), differential scanning calorimetry (DSC), and stability. Particle size analysis revealed that the SLN prepared from the higher melting point lipid showed a larger particle size and with increased carbon chain length of the fatty acids. Entrapment efficiency (EE) was ranging from 42% to 92%. In vitro release studies showed maximum cumulative drug release was obtained for F 1 (59.1%) containing stearic acid, and the lowest was observed for F 18 (28.1%) containing compritol ATO 888 after 12 h and all the formulations followed first-order release kinetics. FT-IR and DSC studies revealed no interaction between drug and lipids. Studies showed that increase in lipid concentration, increased particle size, EE, and maintained the sustained release of drug. Among all, compritol ATO 888 was chosen as the best lipid for formulating SLN because it had high EE and sustained the drug release. PMID:23112531

Priyanka, K; Sathali, A Abdul Hasan

2012-01-01

186

Zn-doping effect on the energy barrier to magnetization reversal in superparamagnetic nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Measurements of ac-susceptibility and dc-magnetization were carried out on samples of Ni1-xZnxFe2O4 nanoparticles (x=0, 0.25, 0.5, 0.75) with average diameters ?7 nm. Values of the superparamagnetic blocking temperature T¯B were obtained from the characteristic temperature behavior of the imaginary susceptibility ?imag. An Arrhenius-type law, which accurately describes the relationship between the observation time ?obs and the blocking temperature, was used to determine the effective energy barrier to magnetization reversal Ueff. A Zn-content dependence of the energy barrier is observed, where Ueff changes little for 0?x?0.25, it peaks at x=0.5, and decreases back upon further Zn-doping. The large increase of Ueff at x=0.5 is attributed to an enhanced magnetic anisotropy induced by the crossover between two spatial arrangements of spins in the A and B sub-lattices of the ferrimagnetic inverse spinel.

Elizalde Galindo, J. T.; Adair, A. H.; Botez, C. E.; Corral Flores, V.; Bueno Baques, D.; Fuentes Cobas, L.; Matutes-Aquino, J. A.

2007-06-01

187

Thiolated chitosan nanoparticles for enhancing oral absorption of docetaxel: preparation, in vitro and ex vivo evaluation  

PubMed Central

The aim of this study was to prepare and evaluate mucoadhesive core-shell nanoparticles based on copolymerization of thiolated chitosan coated on poly methyl methacrylate cores as a carrier for oral delivery of docetaxel. Docetaxel-loaded nanoparticles with various concentrations were prepared via a radical emulsion polymerization method using cerium ammonium nitrate as an initiator. The physicochemical properties of the obtained nanoparticles were characterized by: dynamic light-scattering analysis for their mean size, size distribution, and zeta potential; scanning electron microscopy and transmission electron microscopy for surface morphology; and differential scanning calorimetry analysis for confirmation of molecular dispersity of docetaxel in the nanoparticles. Nanoparticles were spherical with mean diameter below 200 nm, polydispersity of below 0.15, and positive zeta potential values. The entrapment efficiency of the nanoparticles was approximately 90%. In vitro release studies showed a sustained release characteristic for 10 days after a burst release at the beginning. Ex vivo studies showed a significant increase in the transportation of docetaxel from intestinal membrane of rat when formulated as nanoparticles. Cellular uptake of nanoparticles was investigated using fluoresceinamine-loaded nanoparticles. Docetaxel nanoparticles showed a high cytotoxicity effect in the Caco-2 and MCF-7 cell lines after 72 hours. It can be concluded that by combining the advantages of both thiolated polymers and colloidal particles, these nanoparticles can be proposed as a drug carrier system for mucosal delivery of hydrophobic drugs. PMID:21289989

Saremi, Shahrooz; Atyabi, Fatemeh; Akhlaghi, Seyedeh Parinaz; Ostad, Seyed Nasser; Dinarvand, Rassoul

2011-01-01

188

X-ray diffraction studies on crystallite size evolution of CoFe 2O 4 nanoparticles prepared using mechanical alloying and sintering  

NASA Astrophysics Data System (ADS)

Nanosized cobalt ferrite spinel particles have been prepared by using mechanically alloyed nanoparticles. The effects of various preparation parameters on the crystallite size of cobalt ferrite which includes milling time; ball-to powder weight ratio (BPR) and sintering temperature, were studied using X-ray diffractometer (XRD). Scherrer's equation was used to study the crystallite size evolution of the as-prepared materials. The results of the as-milled sample revealed that both milling time and BPR plays a role in determining the crystallite size of the milled powder. However, where sintering is involved, the sintering temperature results in grain growth, and thus plays a dominant role in determining the final crystallite size of the samples sintered at higher temperature (above 900 °C). From the vibrating-sample magnetometer (VSM) measurement it was observed that the coercivity of the as-milled samples without sintering is almost negligible, which is a type characteristic of superparamagnetic material. However, for the sintered samples, the saturation increases while coercivity decreases with increases sintering temperature.

Waje, Samaila Bawa; Hashim, Mansor; Yusoff, Wan Daud Wan; Abbas, Zulkifly

189

The role of fuel concentration on particle size and dielectric properties of manganese substituted zinc ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Mn substituted ZnFe2O4 nanoparticles were prepared by the auto-combustion method using different fuel ratios of 50%, 75% and 100%.The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectrum (EDX). Also, the dielectric behaviors of the samples were investigated for different annealing temperatures. The X-ray diffraction patterns indicated that the annealed samples resulted in the formation of crystalline powder and the presence of ?-Fe2O3 as a secondary phase. The average crystallite sizes of the samples are from ~12 to 60 nm. The external morphology and microstructure of the samples are tested by SEM and TEM. The effect of annealing temperature and particle size on dielectric properties such as dielectric constant (?) and dielectric loss (D) of the spinel MnxZn1-xFe2O4 nanoparticles was measured using impedance analyzer in the frequency range 100 kHz-5 MHz.

Ranjith Kumar, E.; Jayaprakash, R.

2014-10-01

190

Preparation of CoxFe3-xO4 films in aqueous solution at 120-200 °C by ``hydrothermal ferrite plating'' (abstract)  

NASA Astrophysics Data System (ADS)

Ferrite plating facilitates the formation of polycrystalline spinel films in an aqueous solution below 100 °C. The plating temperature can be extended up to 200 °C when the pressure of the reaction solution is kept high (15-20 kgf/cm2). We call this ``hydrothermal ferrite plating,'' by which solubility limit of Ni in Fe3-xNixO4 increases much, from x=0.3 (by conventional ferrite plating at 90 °C) to x=0.93.1 In this paper we describe preparation of Fe3-xCoxO4 films by the hydrothermal ferrite plating at T=120-200 °C and p=15-40 kgf/cm2, and report their structural and magnetic properties. Plating for 1 h, we obtained films about 1 ?m in thickness, which are polycrystalline with no preferential crystal orientation as observed by x-ray diffraction. The solubility limit of Co, which is x=0.6 at 90 °C, increases to x=1.3 at 180 °C. The solubility limit of Co is higher than that of Ni, which may be because Ni tends to keep 2+ state in the spinel structure, while Co can take both 2+ and 3+ states. When prepared at 200 °C, the saturation magnetization of the films are smaller than that reported for bulk samples, though both agree when the films are prepared at 90 °C.2 This suggests that Co is oxidized to 3+ state even when x<1.0 as large as the Fe3-xCoxO4 films are prepared in the hydrothermal conditions. We found that adding CH3COONH4 into the reaction solution as a pH buffer improves the smoothness of the film surface.

Itoh, T.; Zhang, Q.; Abe, M.; Tamaura, Y.

1991-11-01

191

Polymer?Nanoparticle Composites: Preparative Methods and Electronically Active Materials  

Microsoft Academic Search

The field of nanoparticle?polymer composites is attractive from the standpoint of integrating the key features of both polymers and nanoparticles into hybrid or composite materials. Nanocomposites geared towards electronic and photophysical targets comprise an intriguing subset of the field, and benefit from interdisciplinary efforts in nanoparticle and polymer synthesis, along with methodology that provides the dispersion, orientation, and\\/or the assembly

P. K. Sudeep; Todd Emrick

2007-01-01

192

Structural and conductivity analysis on cerium fluoride nanoparticles prepared by sonication assisted method  

NASA Astrophysics Data System (ADS)

The article deals with the effect of sonication on ionic conductivity of cerium fluoride. Cerium fluoride nanoparticles have been prepared by simple precipitation method from aqueous solution with sonication assistance. The structural and morphology of the nanoparticles prepared have been studied using X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopic (FESEM) analysis. The morphological analysis confirms the formation of nanorods. Ac impedance spectroscopy has been used to study the ion conduction and conductivity of the prepared nanoparticles. The surface area of the prepared nanoparticles has been studied by nitrogen adsorption-desorption analysis. From the impedance spectra analysis the sample prepared at 2 h sonication time is found to have high ionic conductivity. The conductance spectra show an orderly shifting which is due to the effect of sonication. The temperature dependence of conductivity follows the Arrhenius behavior.

Arun Kumar, D.; Selvasekarapandian, S.; Nithya, H.; Masuda, Yoshitake

2012-05-01

193

Preparation and characterization of PEG-Mentha oil nanoparticles for housefly control.  

PubMed

Nanoparticles of Mentha × piperita essential oil were prepared by melt-dispersion method. The nanoparticles prepared at varying oil doses (5-10%, w/v) showed an encapsulation efficiency of 78.2-83.4%, while the oil load was observed to range between 3.64 and 7.46%. The average particle size of the nanoparticles varied between 226 and 331 nm, while polydispersity index showed variation between 0.547 and 1.000. DSC analysis indicated endothermic reaction during formation of nanoparticles, while a 2-term exponential kinetic model was followed during oil release. Nanoparticles showed considerable mortality against housefly larvae in lab (100%) as well as simulated field condition after first week (93%) and 6th week (57%) of application. This was the first study utilizing controlled release property of nanoparticles to formulate a cost effective product for breeding site application against housefly. PMID:24287110

Kumar, Peeyush; Mishra, Sapna; Malik, Anushree; Satya, Santosh

2014-04-01

194

Investigation of antibacterial properties silver nanoparticles prepared via green method  

PubMed Central

Background This study aims to investigate the influence of different stirring times on antibacterial activity of silver nanoparticles in polyethylene glycol (PEG) suspension. The silver nanoparticles (Ag-NPs) were prepared by green synthesis method using green agents, polyethylene glycol (PEG) under moderate temperature at different stirring times. Silver nitrate (AgNO3) was taken as the metal precursor while PEG was used as the solid support and polymeric stabilizer. The antibacterial activity of different sizes of nanosilver was investigated against Gram–positive [Staphylococcus aureus] and Gram–negative bacteria [Salmonella typhimurium SL1344] by the disk diffusion method using Müeller–Hinton Agar. Results Formation of Ag-NPs was determined by UV–vis spectroscopy where surface plasmon absorption maxima can be observed at 412–437 nm from the UV–vis spectrum. The synthesized nanoparticles were also characterized by X-ray diffraction (XRD). The peaks in the XRD pattern confirmed that the Ag-NPs possessed a face-centered cubic and peaks of contaminated crystalline phases were unable to be located. Transmission electron microscopy (TEM) revealed that Ag-NPs synthesized were in spherical shape. The optimum stirring time to synthesize smallest particle size was 6 hours with mean diameter of 11.23 nm. Zeta potential results indicate that the stability of the Ag-NPs is increases at the 6 h stirring time of reaction. The Fourier transform infrared (FT-IR) spectrum suggested the complexation present between PEG and Ag-NPs. The Ag-NPs in PEG were effective against all bacteria tested. Higher antibacterial activity was observed for Ag-NPs with smaller size. These suggest that Ag-NPs can be employed as an effective bacteria inhibitor and can be applied in medical field. Conclusions Ag-NPs were successfully synthesized in PEG suspension under moderate temperature at different stirring times. The study clearly showed that the Ag-NPs with different stirring times exhibit inhibition towards the tested gram-positive and gram-negative bacteria. PMID:22839208

2012-01-01

195

Nanoparticle preparation of quinacridone and ?-carotene using near-infrared laser ablation of their crystals  

NASA Astrophysics Data System (ADS)

Quinacridone nanoparticles with a mean size of about 200 nm are successfully prepared using nanosecond near-infrared (NIR) laser ablation of its microcrystalline powders in heavy water. The absorption spectra of the formed colloidal solutions depend on the excitation wavelengths, which is eventually ascribed to number and energy of absorbed photons. ?-carotene has low photostability and is easily decomposed upon UV/VIS laser ablation of its solid, while its nanoparticles are prepared utilizing this NIR laser ablation technique. The advantage of nanoparticle preparation by NIR laser ablation is discussed.

Yuyama, K.; Sugiyama, T.; Asahi, T.; Ryo, S.; Oh, I.; Masuhara, H.

2010-12-01

196

Preparation, characterization and in vitro antiviral activity evaluation of foscarnet-chitosan nanoparticles.  

PubMed

A new nanoparticulate system for foscarnet delivery was prepared and evaluated. Nanoparticles were obtained by ionotropic gelation of chitosan induced by foscarnet itself, acting as an ionotropic agent in a manner similar to tripolyphosphate anion. A Doehlert design allowed finding the suitable experimental conditions. Nanoparticles were between 200 and 300nm in diameter (around 450nm after redispersion). Nanoparticle size increased after 5h, but no size increase was observed after 48h when nanoparticles were crosslinked with glutaraldehyde. Zeta potential values of noncrosslinked and crosslinked nanoparticles were between 20 and 25mV, while drug loading of noncrosslinked nanoparticles was about 40% w/w (55% w/w for crosslinked nanoparticles). Nanoparticle yield was around 25% w/w. Crosslinked nanoparticles showed a controlled drug release. Foscarnet released from nanoparticles maintained the antiviral activity of the free drug when tested in vitro against lung fibroblasts (HELF) cells infected with HCMV strain AD-169. Moreover, nanoparticles showed no toxicity on non-infected HELF cells. These nanoparticles may represent a delivery system that could improve the therapeutic effect of foscarnet. PMID:24742953

Russo, E; Gaglianone, N; Baldassari, S; Parodi, B; Cafaggi, S; Zibana, C; Donalisio, M; Cagno, V; Lembo, D; Caviglioli, G

2014-06-01

197

Preparation and characterization of carboxymethyl guar gum nanoparticles.  

PubMed

Carboxymethyl guar gum nanoparticles (CMGGNPs) were synthesized by nanoprecipitation and sonication method. This method was used for the first time for the synthesis of carboxymethyl guar gum nanoparticles. It was found that the formation of nanoparticles might depend upon the sonication time, solvent, and stirring time. Nanoparticles were characterized by SEM, TEM, XRD and FTIR. The sizes of the particles in suspension have been found in the range 12-30nm. It was concluded that such type of nanoparticles may be used in pharmaceutical and drug delivery. PMID:24832982

Gupta, Anek Pal; Verma, Devendra Kumar

2014-07-01

198

Magnetic properties of zinc ferrite nanoparticles synthesized by hydrolysis in a polyol medium  

NASA Astrophysics Data System (ADS)

Highly crystalline, nanometre sized ZnFe2O4 particles with different diameters, 6.6 and 14.8 nm, were prepared by forced hydrolysis in a polyol medium. The DC magnetic properties exhibit a strong dependence on the particle size as a result of the unusual cation distribution. They clearly establish their superparamagnetic character at room temperature and the occurrence of ferrimagnetic or ferromagnetic ordering at low temperature. The magnetization is found to increase with grain size reduction. The 57Fe Mössbauer spectra were recorded at 300 and 4.5 K. There is no evidence for the presence of the Fe2+ charge state, confirming the perfect stoichiometry of the two samples. At 300 K, the Mössbauer spectra consist of doublets due to the superparamagnetic behaviour whereas at 4.5 K they reveal a magnetically blocked state. Mössbauer spectra at 10 K in an external 6 T magnetic field applied parallel to the direction of the gamma rays clearly show a close to collinear Néel-like ferrimagnetic ordering for the 6.6 nm particles and a canted Yafet-Kittel-like ferrimagnetic ordering for the 14.8 nm ones.

Ammar, Souad; Jouini, Noureddine; Fiévet, Fernand; Beji, Zyed; Smiri, Leila; Moliné, Philippe; Danot, Michel; Grenèche, Jean-Marc

2006-10-01

199

Preparation and optical properties of colloidal silver nanoparticles at a high Ag + concentration  

Microsoft Academic Search

We have prepared colloidal silver nanoparticles by reducing a high molar concentration of AgNO3 (up to 0.735 M) with glycerol in the presence of m-phenylenediamine. These silver nanoparticles had anisotropic shapes, including truncated rectangles, truncated triangles, and spheroid-type particles. The UV–Vis spectra of these nanoparticle systems display two distinct plasmon modes and a shoulder that correspond to the in-plane dipole,

M. Habib Ullah; Kim Il; Chang-Sik Ha

2006-01-01

200

Preparation of neutron-activatable holmium nanoparticles for the treatment of ovarian cancer metastases.  

PubMed

Nanoparticles containing stable holmium ((165) Ho) are prepared by nanotemplate engineering and subsequently irradiated in a neutron flux to yield (166) Ho, a beta-emitting radiotherapeutic isotope. After intraperitoneal injection to mice bearing SKOV-3 ovarian tumors, significant tumor accumulation of the (166) Ho-nanoparticles is observed by SPECT imaging indicating the potential of these neutron activatable nanoparticles for internal radiation therapy of ovarian cancer metastases. PMID:22298503

Di Pasqua, Anthony J; Huckle, James E; Kim, Jin-Ki; Chung, Younjee; Wang, Andrew Z; Jay, Michael; Lu, Xiuling

2012-04-10

201

Chitosan-Pluronic nanoparticles as oral delivery of anticancer gemcitabine: preparation and in vitro study  

PubMed Central

Nanoparticles have proven to be an effective delivery system with few side effects for anticancer drugs. In this study, gemcitabine-loaded nanoparticles have been prepared by an ionic gelation method using chitosan and Pluronic® F-127 as a carrier. Prepared nanoparticles were characterized using dynamic light scattering, Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), scanning electron microscopy, and transmission electron microscopy. Different parameters such as concentration of sodium tripolyphosphate, chitosan, Pluronic, and drug on the properties of the prepared nanoparticles were evaluated. In vitro drug release was studied in phosphate-buffered saline (PBS; pH = 7.4). The cytotoxicity of the nanoparticles was assayed in the HT-29 colon cancer cell line. The mucoadhesion behavior of the nanoparticles was also studied by mucus glycoprotein assay. The prepared nanoparticles had a spherical shape with positive charge and a mean diameter ranging between 80 to 170 nm. FT-IR and DSC studies found that the drug was dispersed in its amorphous form due to its potent interaction with nanoparticle matrix. Maximum drug encapsulation efficiency was achieved at 0.4 mg/mL gemcitabine while maximum drug loading was 6% obtained from 0.6 mg/mL gemcitabine. An in vitro drug release study at 37°C in PBS (pH = 7.4) exhibited a controlled release profile for chitosan–Pluronic® F-127 nanoparticles. A cytotoxicity assay of gemcitabine-loaded nanoparticles showed an increase in the cytotoxicity of gemcitabine embedded in the nanoparticles in comparison with drug alone. The mucoadhesion study results suggest that nanoparticles could be considered as an efficient oral formulation for colon cancer treatment. PMID:22605934

Hosseinzadeh, Hosniyeh; Atyabi, Fatemeh; Dinarvand, Rassoul; Ostad, Seyed Naser

2012-01-01

202

Silver nanoparticles dispersing in chitosan solution: Preparation by ?-ray irradiation and their antimicrobial activities  

Microsoft Academic Search

Silver nanoparticles were prepared by ?-ray irradiation–reduction under simple conditions, i.e., air atmosphere, using chitosan as a stabilizer. The nanoparticles were spherical with an average size of 7–30nm as observed from TEM. The size decreased when chitosan concentration increased, while it increased with increasing ?-ray dose and initial silver nitrate content. The obtained silver nanoparticles dispersed in a 0.5% (w\\/v)

Rangrong Yoksan; Suwabun Chirachanchai

2009-01-01

203

Preparation and Low-Temperature Sintering of Cu Nanoparticles for High-Power Devices  

Microsoft Academic Search

One of the fundamental requirements for high-temperature electronic packaging is reliable silicon attach with low and stable electrical resistance. This paper presents a study conducted on Cu nanoparticles as an alternative lead-free interconnect material for high-temperature applications. Cu nanoparticles were prepared using pulsed wire evaporation technique in water medium. Pure Cu nanoparticles without any organic mixture were used in this

Shutesh Krishnan; A. S. M. A. Haseeb; Mohd Rafie Johan

2012-01-01

204

PEGylated PLGA nanoparticles as protein carriers: synthesis, preparation and biodistribution in rats  

Microsoft Academic Search

The aim of the present work was to assess the merits of PEGylated poly(lactic-co-glycolic acid) (PEG–PLGA) nanoparticles as protein and peptide drugs (PPD) carriers. PEG–PLGA copolymer, which could be used to prepare the stealth nanoparticles or long-circulating nanoparticles, was synthesized with methoxypolyethyleneglycol (MePEG) and PLGA. The structure of PEG–PLGA was confirmed with 1H NMR and Fourier transform infrared (FTIR) spectrum,

Ya-Ping Li; Yuan-Ying Pei; Xian-Ying Zhang; Zhou-Hui Gu; Zhao-Hui Zhou; Wei-Fang Yuan; Jian-Jun Zhou; Jian-Hua Zhu; Xiu-Jian Gao

2001-01-01

205

Gamma radiation roused lattice contraction effects investigated by Mössbauer spectroscopy in nanoparticle Mn-Zn ferrite  

NASA Astrophysics Data System (ADS)

Nanopowders of MnxZn1-xFe2O4 with x=0.4, 0.5 and 0.6 were synthesized using a combustion synthesis method. X-ray diffraction (XRD) patterns obtained on samples confirmed formation of monophasic cubic phase material. Lattice parameters and X-ray densities were obtained from rietvield refinement of the XRD patterns. All samples were radiated with gamma radiation with a dose of 200 Gy obtained from 60Co source. Structural and physical parameters, such as lattice constant, X-ray density and particle size, determined for as prepared samples (SA) and gamma irradiated samples (SR), showed extraordinary variations in their values. Saturation magnetizations (MS), remnant magnetization (MR) and coercive field (HC) for both sets of samples illustrated an enhancement in their values for SR samples. Investigations were carried out using Mössbauer spectroscopy to divulge structural and magnetic information of all samples. Room temperature Mössbauer spectra were fitted with five magnetic sextets and a symmetric paramagnetic doublet for the data obtained on samples except for x=0.4, SA sample. The presence of well defined doublets in the spectra of SA and SR samples is attributes of superparamagnetism, indicating the reduction in A-B superexchange interaction due to dilution of sub-lattice by Zn ions. Cation distribution at A site and B site, estimated from Mössbauer data exhibited amazing alterations which were highly stable. The variations in physical, structural and magnetic properties observed are attributed to change of Fe2+/Fe3+ and Mn+2/Mn+3 ratios in gamma-irradiated samples.

Naik, P. P.; Tangsali, R. B.; Meena, S. S.; Bhatt, Pramod; Sonaye, B.; Sugur, S.

2014-09-01

206

Superparamagnetic iron oxide nanoparticles prepared by using an improved polyol method  

NASA Astrophysics Data System (ADS)

Superparamagnetic iron oxide nanoparticles were synthesized by thermal decomposition of iron (III) acetylacetonate (Fe(acac)3) in PEG containing poly(vinyl pyrrolidone) (PVP) or poly(ethylene imine) (PEI). The morphologies and phase compositions of the nanoparticles were determined by transmission electron microscopy and X-ray diffraction, respectively. The surface coating of the nanoparticles was recognized using Fourier transform infrared spectroscopy and the presence of the surface coating was confirmed by Thermogravimetric analyses. Magnetic properties were measured using superconducting quantum interference device. The zeta potentials and hydrodynamic sizes of the nanoparticles were determined using nano-particle and zeta potential analyzer. The superparamagnetic iron oxide nanoparticles with sizes from 4.1 nm to 14.9 nm were prepared in the present work, which could be tuned by varying factors such as the reaction temperature, the reaction time, and the PVP or PEI contents. The superparamagnetic nanoparticles were jointly coated with PEG/PVP or PEG/PEI. With hydrodynamic sizes smaller than 40 nm and neutral or positive zeta potentials these superparamagnetic iron oxide nanoparticles exhibited higher dispersion stability in deionized water and in phosphate buffered saline as compared with the superparamagnetic iron oxide nanoparticles coated with PEG alone. This work demonstrates that superparamagnetic iron oxide nanoparticles with modulated properties can be prepared simply by using the improved polyol method.

Zhang, Baolin; Tu, Zhijiang; Zhao, Fangyuan; Wang, Jun

2013-02-01

207

Preparation, Characterization, and Release Study of Tacrolimus-Loaded Liquid Crystalline Nanoparticles  

Microsoft Academic Search

Use of liquid crystalline nanoparticles is a novel approach in the field of controlled drug delivery. Tacrolimus, being a highly lipophilic drug, is easily incorporated in the hydrophobic core of these nanoparticles which are prepared using monoolein, distilled water and varying ratios of poloxamer 407. Characterization including Transmission Electron Microscopy (TEM) image, particle size and entrapment efficiency analysis suggested the

Raj Kumar Thapa; Rengarajan Baskaran; Thiagarajan Madheswaran; Jong Oh Kim; Chul Soon Yong; Bong Kyu Yoo

2012-01-01

208

Preparation of avidin-labeled protein nanoparticles as carriers for biotinylated peptide nucleic acid  

Microsoft Academic Search

The possibility of preparing protein nanoparticles followed by covalent linkage of avidin was investigated. Free sulfhydryl groups were introduced onto the surface of protein nanoparticles either by aldehyde quenching with cysteine or reaction of free amino groups with 2-iminothiolane. The number of primary amino groups and sulfhydryl groups on the surface of the resulting particles was quantified with site-specific reagents.

Klaus Langer; Conrad Coester; Carolin Weber; Hagen von Briesen; Jörg Kreuter

2000-01-01

209

SERS active systems of water-soluble polythiophene and plasmonic nanoparticles: preparation and optical properties  

Microsoft Academic Search

Aggregated systems of silver (Ag) and gold (Au) nanoparticles coated with cationic polythiophene were prepared, which showed optical properties typical for strongly coupled plasmonic excitations. The procedure allowed tune up the three-dimensional arrangement of nanoparticles assembly for achieving strong SERS effect at the excitation wavelength depending on the polymer concentration. By combination with an anionic derivative of polythiophene thin multilayer

S. Kazim; J. Pfleger; K. Halasová; M. Procházka; D. Bondarev; J. Vohlídal

2011-01-01

210

Facile Preparation of AuPt Alloy Nanoparticles from Organometallic Complex Precursor  

E-print Network

Facile Preparation of AuPt Alloy Nanoparticles from Organometallic Complex Precursor Jianbo Xu prepared as nanomaterials.6 However, the preparation of AuPt alloy NPs is still com- plicated because of AuPt bimetallic NPs via coreduction method.9 To promote alloy formation, Lang et al.10 demonstrated

Zhao, Tianshou

211

Preparation of PtNi Nanoparticles for the Electrocatalytic Oxidation of Methanol  

E-print Network

Carbon supported PtNi nanoparticles were prepared by hydrazine reduction of Pt and Ni precursor salts under different conditions, namely by conventional heating (PtNi-1), by prolonged reaction at room temperature (PtNi-2) ...

Deivaraj, T.C.

212

X-ray powder diffraction line broadening analysis and magnetism of interacting ferrite nanoparticles obtained from acetylacetonato complexes  

Microsoft Academic Search

A study of the microstructures and magnetic properties of nanosize Zn ferrite (ZnFe2O4), Mn ferrite (MnFe2O4), and the cation deficit Zn-Mn ferrites Zn0.70Mn0.23Fe1.89O4 (S1), Zn0.41Mn0.50Fe1.84O4 (S2) and Zn0.18Mn0.67Fe1.85O4 (S3) was performed. The crystallite size for all samples was determined by x-ray powder diffraction (XRPD) analysis using four different methods, and was close to the particle size found from transmission electron

A. Kremenovic; B. Antic; V. Spasojevic; M. Vucinic-Vasic; Z. Jaglicic; J. Pirnat; Z. Trontelj

2005-01-01

213

Preparation, magnetic characterization, and optical band gap of EuTiO 3 nanoparticles  

Microsoft Academic Search

Perovskite-type polycrystalline EuTiO3 (ETO) nanoparticles were synthesized using the simple sol–gel technique. We investigated the magnetic properties of the as-prepared ETO nanoparticles and revealed the G-AFM phase below the Néel temperature (TN). Furthermore, the transition from the G-AFM order to the FM order, induced by magnetic field, was also demonstrated. The optical band gap of 1.03eV for the as-prepared ETO

T. Wei; H. P. Liu; Y. F. Chen; H. Y. Yan; J.-M. Liu

2011-01-01

214

PLGA nanoparticles prepared by nanoprecipitation: drug loading and release studies of a water soluble drug  

Microsoft Academic Search

The nanoprecipitation technique for preparation of nanoparticles suffers the drawback of poor incorporation of water soluble drugs. The aim of this study was therefore to assess various formulation parameters to enhance the incorporation of a water soluble drug (procaine hydrochloride) into poly(dl-lactide-co-glycolide) (PLGA) nanoparticles prepared by this technique. Approaches investigated for drug incorporation efficiency enhancement included the influence of aqueous

Thirumala Govender; Snjezana Stolnik; Martin C. Garnett; Lisbeth Illum; Stanley S. Davis

1999-01-01

215

Preparation and characterization of bioactive glass nanoparticles prepared by sol-gel for biomedical applications.  

PubMed

Bioactive glass nanoparticles (BG-NPs), based on both ternary (SiO(2)-CaO-P(2)O(5)) and binary (SiO(2)-CaO) systems, were prepared via an optimized sol-gel method. The pH of preparation and the effect of heat treatment temperature were evaluated, as well as the effect of suppressing P in the bioactivity ability of the materials. The morphology and composition of the BG-NPs were studied using FTIR, XRD and SEM. The bioactive character of these materials was accessed in vitro by analyzing the ability for apatite formation onto the surface after being immersed in simulated body fluid (SBF). XRD, EDX and SEM were used to confirm the bioactivity of the materials. The BG-NP effect on cell metabolic activity was assessed by seeding L929 cells with their leachables, proving the non-cytotoxicity of the materials. Finally the most bioactive BG-NPs developed (ternary system prepared at pH 11.5 and treated at 700?°C) were successfully combined with chitosan in the production of biomimetic nanocomposite osteoconductive membranes that could have the potential to be used in guided tissue regeneration. PMID:22101770

Luz, Gisela M; Mano, João F

2011-12-01

216

Preparation and characterization of bioactive glass nanoparticles prepared by sol-gel for biomedical applications  

NASA Astrophysics Data System (ADS)

Bioactive glass nanoparticles (BG-NPs), based on both ternary (SiO2-CaO-P2O5) and binary (SiO2-CaO) systems, were prepared via an optimized sol-gel method. The pH of preparation and the effect of heat treatment temperature were evaluated, as well as the effect of suppressing P in the bioactivity ability of the materials. The morphology and composition of the BG-NPs were studied using FTIR, XRD and SEM. The bioactive character of these materials was accessed in vitro by analyzing the ability for apatite formation onto the surface after being immersed in simulated body fluid (SBF). XRD, EDX and SEM were used to confirm the bioactivity of the materials. The BG-NP effect on cell metabolic activity was assessed by seeding L929 cells with their leachables, proving the non-cytotoxicity of the materials. Finally the most bioactive BG-NPs developed (ternary system prepared at pH 11.5 and treated at 700 °C) were successfully combined with chitosan in the production of biomimetic nanocomposite osteoconductive membranes that could have the potential to be used in guided tissue regeneration.

Luz, Gisela M.; Mano, João F.

2011-12-01

217

Water driven stabilization of ZnS nanoparticles prepared by exploding wire technique  

NASA Astrophysics Data System (ADS)

ZnS nanoparticles, prepared employing exploding wire technique (EWT), demonstrate water-induced stabilization with time. The structural evolution of ZnS nanoparticles and their interaction with the surrounding aqueous media is systematically studied at the three distinct stages of time. The structural properties of nanoparticles were examined by an assortment of characterization techniques. However, in this article we focus on x-ray diffraction (XRD) and x-ray photoelectron spectroscopic (XPS) investigation of nanoparticles. The XRD results indicate transformation of hexagonal phase of prepared ZnS nanocrystals. The lattice constants and strain in ZnS nanoparticles are estimated at each stage of transition. Alteration in crystal structure of ZnS nanoparticles, transforming in presence of water, is an outcome of gradual variation in lattice constants and strain. Variation in stoichiometry of ZnS nanoparticles, at respective stages of transformation, is found through XPS analysis. Furthermore, in order to determine the alterations in the oxidation state and energies of the nanoparticle constituents, line shape analysis of Zn 2p3/2 peaks at three stages, is also performed. Thus, XPS analysis, accompanied with the XRD interpretations, vividly deciphers the structural evolution of ZnS nanoparticles in aqueous environment.

Goswami, Navendu; Sen, P.

2014-04-01

218

SERS active systems of water-soluble polythiophene and plasmonic nanoparticles: preparation and optical properties  

NASA Astrophysics Data System (ADS)

Aggregated systems of silver (Ag) and gold (Au) nanoparticles coated with cationic polythiophene were prepared, which showed optical properties typical for strongly coupled plasmonic excitations. The procedure allowed tune up the three-dimensional arrangement of nanoparticles assembly for achieving strong SERS effect at the excitation wavelength depending on the polymer concentration. By combination with an anionic derivative of polythiophene thin multilayer films composed of alternating anionic and cationic polythiophene with mutually interacting plasmonic Au nanoparticles were successfully prepared using layer-by-layer deposition.

Kazim, S.; Pfleger, J.; Halašová, K.; Procházka, M.; Bondarev, D.; Vohlídal, J.

2011-08-01

219

Preparation of Ag/Au/Pt nanoparticles and their catalytic properties  

NASA Astrophysics Data System (ADS)

The Pt deposited on hollow Ag/Au nanoparticles (Ag/Au/Pt) was successfully prepared by a successive reduction method. In general, no absorption peak at UV-visible region similar to that of Pt nanoparticles was observed for these Ag/Au/Pt nanoparticles. Almost spherical nanoparticles with average size around 20 nm were revealed by TEM. The presence of constituent metal of Ag/Au/Pt was confirmed by EDS. The catalytic properties of Ag/Au/Pt for methanol oxidation were investigated by cyclic voltammetry. The peak current density of the Ag/Au/Pt nanoparticles is higher than that of Pt nanoparticles, indicating their better potential of an electrocatalytic activity for methanol oxidation.

Ongartkit, Arisa; Ananta, Supon; Srisombat, Laongnuan

2014-06-01

220

Enzymatic polymerizations using surfactant microstructures and the preparation of polymer-ferrite composites  

SciTech Connect

Horseradish peroxidase has been used as a biocatalyst to synthesize a polymeric material from alkyl-substituted phenols. The synthesis is carried out in a surfactant-based microemulsion environment, with the monomer partitioned at the oil/water interface. The spherical nature of the microemulsion nanodroplets may be acting as a template for the polymer synthesis. The resultant polymer particles are spherical and typically in the submicron size range. The characteristics of the morphology development are described. The templating effect of the surfactant environment becomes more evident when the polymer particles are fully dissolved in a suitable solvent and refolded in the presence of surfactant. Interestingly, submicron-sized spherical particles are obtained only in the presence of surfactant, and particles of arbitrary morphology are seen in the absence of surfactant. Aspects of morphology development leading to the preparation of polymer-iron oxide composites are described.

Kommareddi, N.S.; Tata, M.; Karayigitoglu, C. [Tulane Univ., New Orleans, LA (United States)] [and others

1995-12-31

221

Preparation and measurement methods for studying nanoparticle aggregate surface chemistry.  

PubMed

Despite best efforts at controlling nanoparticle (NP) surface chemistries, the environment surrounding nanomaterials is always changing and can impart a permanent chemical memory. We present a set of preparation and measurement methods to be used as the foundation for studying the surface chemical memory of engineered NP aggregates. We attempt to bridge the gap between controlled lab studies and real-world NP samples, specifically TiO(2), by using well-characterized and consistently synthesized NPs, controllably producing NP aggregates with precision drop-on-demand inkjet printing for subsequent chemical measurements, monitoring the physical morphology of the NP aggregate depositions with scanning electron microscopy (SEM), acquiring "surface-to-bulk" mass spectra of the NP aggregate surfaces with time-of-flight secondary ion mass spectrometry (ToF-SIMS), and developing a data analysis scheme to interpret chemical signatures more accurately from thousands of data files. We present differences in mass spectral peak ratios for bare TiO(2) NPs compared to NPs mixed separately with natural organic matter (NOM) or pond water. The results suggest that subtle changes in the local environment can alter the surface chemistry of TiO(2) NPs, as monitored by Ti(+)/TiO(+) and Ti(+)/C(3)H(5)(+) peak ratios. The subtle changes in the absolute surface chemistry of NP aggregates vs. that of the subsurface are explored. It is envisioned that the methods developed herein can be adapted for monitoring the surface chemistries of a variety of engineered NPs obtained from diverse natural environments. PMID:22706074

Szakal, Christopher; McCarthy, James A; Ugelow, Melissa S; Konicek, Andrew R; Louis, Kacie; Yezer, Benjamin; Herzing, Andrew A; Hamers, Robert J; Holbrook, R David

2012-07-01

222

Preparation and in-vitro evaluation of indomethacin nanoparticles  

PubMed Central

Background and the purpose of the study During the last two decades one of the most important problems in drug formulations has been low aqueous solubility of new molecules. However, numerous techniques, such as milling, co-solvent solubilization and solid dispersion have been used conventionally for aqueous solubility enhancement and the rate of solubility. Recently, nanoparticle engineering processes have been developed and reported for pharmaceutical applications to increase the dissolution rate of low-soluble drugs which in turn may leads to substantial increases in bioavailability. In this study, a controlled precipitation method was used to produce indomethacin nano-solid suspension in a polymeric matrix (as a model), in order to increase the solubility and rate of the dissolution of poorly soluble model drug. Methods Nano-solid suspension of indomethacin in polyvinyl pyrrolidine (PVP) was prepared by controlled precipitation technique, characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and evaluated for in vitro solubility and dissolution rate. Results and major conclusion Absence of thermal and diffractional peaks in DSC and XRD studies indicated that indomethacin interacts with PVP in solid phase. The solubility of indomethacin in nano-solid suspension compared to crystalline form was increased to about four-fold. It was found that particle size distribution depend to the polymer MW and drug: polymer ratios. Spectroscopy methods and Transmission Electron Microscopy (TEM) images showed that indomethacin dispersed as amorphous nanosize particles in freeze dried powder. Enhanced solubility and dissolution rate of indomethacin compared to physical mixtures and crystalline form of indomethacin (polymorph I), demonstrated that it interacts with PVP via hydrogen bond and probably forming eutectic mixture. PMID:22615616

Rezaei Mokarram, A.; Kebriaee zadeh, A.; Keshavarz, M.; Ahmadi, A.; Mohtat, B.

2010-01-01

223

Preparation and characterization of carvacrol loaded polyhydroxybutyrate nanoparticles by nanoprecipitation and dialysis methods.  

PubMed

In this investigation, preparation of carvacrol loaded polyhydroxybutyrate (PHB) nanoparticles was performed by nanoprecipitation and dialysis methods. PHB particles were obtained by nanoprecipitation method without and with low concentration of Tween 80 or pluronic as surfactant. Nano- and micro-sized particles were formed with trimodal distribution and large aggregates. Size and distribution of nanoparticles were decreased when concentration of Tween 80 was increased to 1% (v/v) in water as polar phase. PHB nanoparticles had narrow size (157 nm) with monomodal distribution. Nanoparticles, which were prepared by dialysis method had 140 nm in diameter with monomodal distribution. Carvacrol was used as a lipophilic drug and entrapped in optimized nanoparticles formulation by nanoprecipitation and dialysis methods. Entrapment efficacy was 21% and 11%, respectively. Morphology of PHB nanoparticles was spherical. The results of kinetic release study showed that carvacrol was released for at least 3 days. Release kinetic parameters showed a simple Fickian diffusion behavior for both formulations. Carvacrol loaded PHB nanoparticles had good dispersion into the agar medium and antimicrobial activity against Escherichia coli. This study describes the 1st work on loading of carvacrol into the PHB nanoparticles by nanoprecipitation and dialysis methods. PMID:24621231

Shakeri, Fatemeh; Shakeri, Shahryar; Hojjatoleslami, Mohammad

2014-04-01

224

Stability, size and optical properties of colloidal silver nanoparticles prepared by electrical arc discharge in water  

NASA Astrophysics Data System (ADS)

We have fabricated and characterised colloidal silver nanoparticles by the electrical arc discharge method in DI water. Size and optical properties of the silver nanoparticles were studied versus different arc currents. Optical absorption indicates a plasmonic peak at 392 nm for 10 A which increases to 398 nm for 20 A arc current. This reveals that by raising the arc current the size of the nanoparticles increases. Optical absorption of silver nanoparticles after 3 weeks shows precipitation of them in a water medium. The effect of different surfactant and stabilizer concentrations such as cethyl trimethylammonium bromide (CTAB), polyvinyl pyrrolidone (PVP), sodium citrate, sodium dodecyl sulfate (SDS), sodium di-2-ethylsulfosuccinate (AOT) and carboxymethyl cellulose (CMC) on the stability of silver nanoparticles was investigated. The colloidal silver nanoparticles with 100 ?M concentration were stable for more than 3 months at 50 ?M CTAB and 6 months at 10 ?M sodium citrate concentration, respectively. SEM images of the sample prepared at 50 ?M CTAB concentration reveal uniform and fine nanoparticles. The mean size from TEM images is about 14 nm. TEM images of the sample prepared at 10 ?M sodium citrate concentration show a shell of citrate that covers the silver nanoparticles.

Ashkarran, A. A.; Iraji Zad, A.; Ahadian, M. M.; Hormozi Nezhad, M. R.

2009-10-01

225

Enhanced bioavailability of sirolimus via preparation of solid dispersion nanoparticles using a supercritical antisolvent process  

PubMed Central

Background The aim of this study was to improve the physicochemical properties and bioavailability of poorly water-soluble sirolimus via preparation of a solid dispersion of nanoparticles using a supercritical antisolvent (SAS) process. Methods First, excipients for enhancing the stability and solubility of sirolimus were screened. Second, using the SAS process, solid dispersions of sirolimus-polyvinylpyrrolidone (PVP) K30 nanoparticles were prepared with or without surfactants such as sodium lauryl sulfate (SLS), tocopheryl propylene glycol succinate, Sucroester 15, Gelucire 50/13, and Myrj 52. A mean particle size of approximately 250 nm was obtained for PVP K30-sirolimus nanoparticles. Solid state characterization, kinetic solubility, powder dissolution, stability, and pharmacokinetics were analyzed in rats. Results X-ray diffraction, differential scanning calorimetry, and high-pressure liquid chromatography indicated that sirolimus existed in an anhydrous amorphous form within a solid dispersion of nanoparticles and that no degradation occurred after SAS processing. The improved supersaturation and dissolution of sirolimus as a solid dispersion of nanoparticles appeared to be well correlated with enhanced bioavailability of oral sirolimus in rats. With oral administration of a solid dispersion of PVP K30-SLS-sirolimus nanoparticles, the peak concentration and AUC0?12h of sirolimus were increased by approximately 18.3-fold and 15.2-fold, respectively. Conclusion The results of this study suggest that preparation of PVP K30-sirolimus-surfactant nanoparticles using the SAS process may be a promising approach for improving the bioavailability of sirolimus. PMID:22162657

Kim, Min-Soo; Kim, Jeong-Soo; Park, Hee Jun; Cho, Won Kyung; Cha, Kwang-Ho; Hwang, Sung-Joo

2011-01-01

226

Preparation and thermoelectric properties of sulfur doped Ag2Te nanoparticles via solvothermal methods  

NASA Astrophysics Data System (ADS)

In this work, n-type Ag2Te nanoparticles are prepared by a solvothermal approach with uniform and controllable sizes, e.g. 5-15 nm. The usage of dodecanethiol during the synthesis effectively introduces sulfur doping into the sample, which optimizes the charge carrier concentration of the nanoparticles to >1 × 1020 cm-3. This allows us to achieve the desired electrical resistivities of <5 × 10-6 ? m. It is demonstrated that Ag2Te particles prepared by this solvothermal process can exhibit high ZT values, e.g. 15 nm Ag2Te nanoparticles with effective sulphur doping show a maximum ZT value of ~0.62 at 550 K.In this work, n-type Ag2Te nanoparticles are prepared by a solvothermal approach with uniform and controllable sizes, e.g. 5-15 nm. The usage of dodecanethiol during the synthesis effectively introduces sulfur doping into the sample, which optimizes the charge carrier concentration of the nanoparticles to >1 × 1020 cm-3. This allows us to achieve the desired electrical resistivities of <5 × 10-6 ? m. It is demonstrated that Ag2Te particles prepared by this solvothermal process can exhibit high ZT values, e.g. 15 nm Ag2Te nanoparticles with effective sulphur doping show a maximum ZT value of ~0.62 at 550 K. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30469d

Zhou, Wenwen; Zhao, Weiyun; Lu, Ziyang; Zhu, Jixin; Fan, Shufen; Ma, Jan; Hng, Huey Hoon; Yan, Qingyu

2012-06-01

227

Simple, clean preparation method for cross-linked ?-cyclodextrin nanoparticles via inclusion complexation.  

PubMed

A simple, clean method was presented in this letter to prepare cross-linked ?-cyclodextrin (?-CD) nanoparticles with a low dispersion. The nanoparticles were synthesized in water by cross-linking the inclusion complex of ?-CDs and poly(ethylene glycol) (PEG). The structure of the nanoparticles was characterized by (1)H NMR, nuclear overhauser enhancement spectroscopy (NOESY), and wide-angle X-ray diffraction (XRD). Spherical morphology was observed by scanning electron microscopy (SEM) for these nanoparticles. Their average hydrodynamic radius was determined to be 67 nm by dynamic light scattering (DLS). Small guest molecules could be included in the cross-linked ?-CD nanoparticles, and anticancer drug cisplatin was used to evaluate the drug release behavior. PMID:23472675

Zhu, Wen; Zhang, Ke; Chen, Yongming; Xi, Fu

2013-05-21

228

Development of alpha-tocopherol acetate nanoparticles: influence of preparative processes.  

PubMed

We studied different methods of preparing alpha-tocopherol acetate (ATA) nanoparticles, which are to be used in targeting the lungs as aerosols in order to prevent cigarette smoke toxicity. Poly-(lactide) nanoparticles were prepared using nanoprecipitation and solvent evaporation techniques, which produced, respectively, too small and too large nanoparticles to be aerosolized. The emulsification-diffusion method produced 2 months stable nanoparticles with a size between (500-700 nm). Increasing ATA concentration (1-7 mg/mL) induced a decrease in the association rate (97-93%) and in the adsorbed ATA rate (7-4.5%), which was associated with variations of Zeta potentials (-27.5 to -24.3 mV) and decrease in polymeric wall thickness and density. PMID:19169943

Anais, J P; Razzouq, N; Carvalho, M; Fernandez, C; Astier, A; Paul, M; Astier, A; Fessi, H; Lorino, A M

2009-02-01

229

Colloidally prepared platinum nanoparticles deposited on iron oxide studied by XAFS  

NASA Astrophysics Data System (ADS)

Colloidal chemistry is an attractive method for the preparation of metal nanoparticles with well-defined shape and size rendering. This preparation technique is particularly interesting for the fabrication of heterogeneous catalysts, where size and shape play a key role for the catalytic properties. Nevertheless, the metal nanoparticles synthesized by colloidal approaches are often surrounded by a shell of organic ligands stabilizing the particles during the growth process. The influence of the ligands on the interaction with the support and the catalytic reaction was studied by x-ray absorption spectroscopy (XAS). It was found that the activity of the metallic Pt nanoparticles previously protected by organic ligands is higher in CO reaction than for unprotected nanoparticles deposited on iron oxide.

Piskorska-Hommel, E.; Arndt, D.; Wilkens, T.; Falta, J.; Bäumer, M.

2013-04-01

230

Nanoprecipitation versus two step desolvation technique for the preparation of gelatin nanoparticles  

NASA Astrophysics Data System (ADS)

Various techniques have been used for preparation of gelatin nanoparticles, such as coacervation, emulsion/solvent evaporation, reverse phase preparation, inverse miniemulsion and two step desolvation. Both methods are based on different mechanisms of nanoparticle formation. The main goal of this study was to systematically compare the performance of nanoprecipitation and the most widely utilized two step desolvation methods with respect to effect of gelatin concentration on nanoparticle size and polydispersity index. Particles size was determined by dynamic light scattering, and the morphology by atomic force microscopy. It was observed that gelatin concentration 20 mg/ml yielded nanoparticles of around 60 nm size by two step desolvation, on the other hand nanoprecipitation produced 210 nm particles with the same gelatin concentration.

Khan, Saeed Ahmad; Schneider, Marc

2013-02-01

231

A Novel Preparation Method for 5-Aminosalicylic Acid Loaded Eudragit S100 Nanoparticles  

PubMed Central

In this study, solution enhanced dispersion by supercritical fluids (SEDS) technique was applied for the preparation of 5-aminosalicylic acid (5-ASA) loaded Eudragit S100 (EU S100) nanoparticles. The effects of various process variables including pressure, temperature, 5-ASA concentration and solution flow rate on morphology, particle size, 5-ASA loading and entrapment efficiency of nanoparticles were investigated. Under the appropriate conditions, drug-loaded nanoparticles exhibited a spherical shape and small particle size with narrow particle size distribution. In addition, the nanoparticles prepared were characterized by X-ray diffraction, Differential scanning calorimetry and Fourier transform infrared spectroscopy analyses. The results showed that 5-ASA was imbedded into EU S100 in an amorphous state after SEDS processing and the SEDS process did not induce degradation of 5-ASA. PMID:22754377

Hu, Daode; Liu, Liang; Chen, Wenjuan; Li, Sining; Zhao, Yaping

2012-01-01

232

Flash microwave synthesis of trevorite nanoparticles  

NASA Astrophysics Data System (ADS)

Nickel ferrite nanoparticles have several possible applications as cathode materials for rechargeable batteries, named "lithium-ion" batteries. In this study, NiFe 2O 4 was prepared by microwave induced thermohydrolysis. The obtained nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), BET method, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). All the results show that the microwave one-step flash synthesis leads in a very short time to NiFe 2O 4 nanoparticles with elementary particles size close to 4-5 nm, and high specific surfaces (close to 240 m 2/g). Thus, microwave heating appears as an efficient source of energy to produce quickly nanoparticles with complex composition as ferrite.

Bousquet-Berthelin, C.; Chaumont, D.; Stuerga, D.

2008-03-01

233

Preparation of Concentrated Stable Fluids Containing Silver Nanoparticles in Nonpolar Organic Solvent  

Microsoft Academic Search

Stable fluids containing silver nanoparticles in kerosene have been prepared by the extraction?reduction method. Silver nitrate was extracted in nonpolar solvent by thio?substituted phosphinic acid extractant Cyanex 302, and then Ag was reduced by solid KBH4. In order to enhance the loading content of silver nanoparticles in the fluids, a tri?block copolymer (PEO)20(PPO)70(PEO)20 was added into the organic phase before

Fu Xun; Yu Wei; Lin Yusheng; Wang Debao; Shi Huaqiang; Yan Fengyuan

2005-01-01

234

PREPARATION OF ZINC OXIDE NANOPARTICLE VIA UNIFORM PRECIPITATION METHOD AND ITS SURFACE MODIFICATION BY METHACRYLOXYPROPYLTRIMETHOXYSILANE  

Microsoft Academic Search

Zinc oxide nanoparticles were prepared by uniform precipitation using urea hydrolysis. The ZnO precursor was slowly deposited from aqueous solution. Anionic surfactant was added into solution to block ZnO crystal growth and its agglomeration. Then ZnO nanoparticles were synthesized by the calcination of the precursor at high temperature. Transmission electron microscope (TEM) observation and particle size analyzer demonstrated that the

Erjun Tang; Baoyong Tian; Erli Zheng; Cuiyan Fu; Guoxiang Cheng

2008-01-01

235

Growth of fullerene nanoparticles prepared by the gas-evaporation technique  

Microsoft Academic Search

C60 and C70 fullerene nanoparticles prepared by evaporating their powders in inert gas were investigated by electron microscopy and X-ray diffraction. Crystal structures of the particles were face centred cubic (fcc) which is a stable phase at high temperature, with lattice parameters of a=1.42 nm for C60 and a=1.499 nm for C70. Nanoparticles with definite crystal habits were sometimes observed

T. Ohno; S. Yatsuya

1998-01-01

236

Effects of Microemulsion Preparation Conditions on Drug Encapsulation Efficiency of PLGA Nanoparticles  

NASA Astrophysics Data System (ADS)

Emulsion solvent evaporation technique is widely used to prepare nanoparticles of many organic polymer drug carriers. The mechanism of nanoparticle generation by this technique involves oil-in-water (O/W) microemulsion formation followed by solvent evaporation. Various microemulsion preparation conditions can affect the encapsulation efficiency of drug in the nanoparticulate carrier. In this study, emulsifying speed, emulsifying temperature, and organic-to-aqueous phase ratio were varied and the resulting encapsulation efficiency of a model drug in Poly(Lactide-co-Glycolide) (PLGA) nanoparticles was determined. The organic phase containing PLGA and a model drug dissolved in chloroform was first dispersed in an aqueous solution containing 0.5 %(w/v) Poly(vinyl alcohol) (PVA), which was then homogenized at high speeds. The resulting O/W microemulsion was subsequently subjected to stirring at room temperature for four hours during which the solvent diffused and evaporated gradually. The fine white suspension was centrifuged and freeze-dried. The model drug loading in the PLGA nanoparticles was determined using UV spectrophotometry. Results showed that the encapsulation efficiency of a model drug, salicylic acid, ranged from 8.5% to 17% depending on the microemulsion preparation conditions. Under the same temperature (15 °C) and homogenization speed (19000 rpm) conditions studied, a relatively high organic-to-aqueous phase ratio (1:5) provided salicylic acid loaded PLGA nanoparticles with significantly higher drug encapsulation efficiency. In addition, under all microemulsion preparation conditions, PLGA nanoparticles obtained after solvent evaporation and freeze drying were spherical and aggregation between the nanoparticles was not observed under a high power microscope. This indicates that PLGA nanoparticles with desirable amount of drug and with anticipated size and shape can be realized by controlling emulsification process conditions.

Ng, Set Hui; Ooi, Ing Hong

2011-12-01

237

Structural and magnetic properties of Mn nanoparticles prepared by arc-discharge  

Microsoft Academic Search

Mn nanoparticles are prepared by arc discharge technique. MnO, ?-Mn, ?-Mn, and ?-Mn are detected by X-ray diffraction, while the presence of Mn3O4 and MnO2 is revealed by X-ray photoelectron spectroscopy. Transmission electron microscopy observations show that most of the Mn nanoparticles have irregular shapes, rough surfaces and a shell\\/core structure, with sizes ranging from several nanometers to 80nm. The

P. Z.. Si; E. H. Brück; Z. D. Zhang; O. Tegus; W. S. Zhang; K. H. J. Buschow; J. C. P. Klaasse

2005-01-01

238

Preparation and characterization of Ag nanoparticle-embedded blank and ligand-anchored silica gels.  

PubMed

Ag nanoparticles, used for halogen (especially iodine) adsorption and an evaluation of halogen behavior, were embedded in synthesized inorganic-organic hybrid gels. In particular, an irradiation method using an electron beam plays a part in introducing Ag nanoparticles to the organofunctionalized silica gels from AgNO3 solutions in a simple way at atmospheric pressure and room temperature. For preparation of the Ag nanoparticle-embedded inorganic-organic hybrid gels, ligands of ethylenediamine (NH2CH2CH2NH-, TMSen) and mercapto (HS-) functionalized three-dimensional porous SiO2 sol-gels were first synthesized through hydrolysis and condensation reactions, and Ag nanoparticles were then embedded into the ethylenediamine- and mercapto-anchored silica gels each, through electron-beam irradiation. The addition of ligands yielded larger average pore sizes than the absence of any ligand. Moreover, the ethylenediamine ligand led to looser structures and better access of the Ag nanoparticles to the ethylenediamine-anchored gel. As a result, more Ag nanoparticles were introduced into the ethylenediamine-anchored gel. The preparation and characterization of Ag nanoparticle-embedded blank and ligand-anchored silica gels are discussed in detail. PMID:24245307

Im, Hee-Jung; Lee, Byung Cheol; Yeon, Jei-Won

2013-11-01

239

Preparation of Pd\\/Pt Bimetallic Nanoparticles in Water\\/AOT\\/Isooctane Microemulsions  

Microsoft Academic Search

Bimetallic nanoparticles of Pd and Pt at various molar ratios have been prepared by the coreduction of H2PdCl4 and H2PtCl6 with hydrazine in water\\/AOT\\/isooctane microemulsions at 25°C. The size, structure, and composition of the resultant nanoparticles were characterized by TEM, XRD, EDX, and XPS. It was shown that the bimetallic nanoparticles obtained at feeding compositions of [H2PdCl4]\\/[H2PtCl6]=9\\/1?1\\/9 were essentially monodispersed

Ming-Li Wu; Dong-Hwang Chen; Ting-Chia Huang

2001-01-01

240

Preparation and biomedical application of a non-polymer coated superparamagnetic nanoparticle  

PubMed Central

We report the preparation of a non-polymer coated superparamagnetic nanoparticle that is stable and biocompatible both in vitro and in vivo. The non-polymer, betaine, is a natural methylating agent in mammalian liver with active surface property. Upon systemic administration, the nanoparticle has preferential biodistribution in mammalian liver and exhibits good reduction of relaxivity time and negative enhancement for the detection of hepatoma nodules in rats using MRI. Our data demonstrate that the non-polymer coated superparamagnetic nanoparticle should have potential applications in biomedicine. PMID:18203447

Du, Lin; Chen, Jianzhao; Qi, Yanting; Li, Dan; Yuan, Chonggang; Lin, Marie C; Yew, David T; Kung, Hsiang-Fu; Yu, Jimmy C; Lai, Lihui

2007-01-01

241

Antibacterial activity of ZnO nanoparticles prepared via non-hydrolytic solution route  

Microsoft Academic Search

The antibacterial activity of ZnO nanoparticles has been investigated and presented in this paper. Nanoparticles were prepared\\u000a via non-hydrolytic solution process using zinc acetate di-hydrate (Zn(CH3COO)2·2H2O) and aniline (C6H5NH2) in 6 h refluxing at ?65 °C. In the presence of four pathogens such as Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Klebsiella pneumoniae, the antibacterial study of zinc oxide nanoparticles were observed.

Rizwan Wahab; Amrita Mishra; Soon-Il Yun; Young-Soon Kim; Hyung-Shik Shin

2010-01-01

242

Preparation of TiO 2 nanoparticles by submerged arc nanoparticle synthesis system  

Microsoft Academic Search

This study investigated the effects of process parameters on geometrical features of titanium dioxide (TiO2) nanoparticles synthesized by the submerged arc nanoparticle synthesis system (SANSS). The synthesis process involves vaporizing a pure titanium rod by a submerged arc in deionized liquid under a controlled vacuum environment, followed by rapid quenching of the vaporized titanium gas by a cooling system, thus

Liang-Chia Chen

2010-01-01

243

Preparation and Characterization of Magnetite (Fe3O4) Nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetite (Fe3O4) nanoparticles exhibit a superparamagnetic behavior when small. Our goal is to fabricate such particles and characterize their structural and magnetic properties as function of particle size and synthesis route. I will show the different fabrication methods we have utilized: one inorganic salt mixing method, an inorganic solution method, and lastly an organic solution method. The last approach should allow us to achieve monolayers of nanoparticles. I will present X-ray diffraction (XRD) results as well as Vibrating Sample Magnetometry (VSM) results, including Field Cooling (FC) versus Zero Field Cooling (ZFC) measurements to find the blocking temperature, or when the magnetic moments are frozen; to complement the magnetometry measurements. We will also include images of nanoparticles deposited on a wafer, recorded by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM).

Trevino, Matea; Chesnel, Karine; Olsen, Betsy; Hancock, Jared; Harrison, Roger; Farrer, Jeffrey

2011-10-01

244

Preparation of Gold Nanoparticles Using Tea: A Green Chemistry Experiment  

ERIC Educational Resources Information Center

Assimilating green chemistry principles in nanotechnology is a developing area of nanoscience research nowadays. Thus, there is a growing demand to develop environmentally friendly and sustainable methods for the synthesis of nanoparticles that utilize nontoxic chemicals, environmentally benign solvents, and renewable materials to avoid their…

Sharma, R. K.; Gulati, Shikha; Mehta, Shilpa

2012-01-01

245

Preparation and characterization of curcumin-piperine dual drug loaded nanoparticles  

PubMed Central

Objective To prepare curcumin-piperine (Cu-Pi) nanoparticles by various methods and to study the effect of various manufacturing parameters on Cu-Pi nanoparticles and to identify a suitable method for the preparation of Cu-Pi nanoparticles to overcome oral bioavailability and cancer cell targeting limitations in the treatment of cancer. Methods Cu-Pi nanoparticles were prepared by thin film hydration method, solid dispersion method, emulsion polymerization method and Fessi method. Optimization was carried out to study the effect of various manufacturing parameter on the Cu-Pi nanoparticles. Results Out of four methods, Fessi method produced a minimum average particle size of 85.43 nm with a polydispersity index of 0.183 and zeta potential of 29.7 mV. Change of organic solvent (acetone or ethanol) did not have any significant effect on Cu-Pi nanoparticles. However, increase in sonication time, stirring speed, viscosity, use of 1:10:10 ratio of drug/polymer/surfactant, and use of anionic surfactant or combination of anionic surfactant with cationic polymer or combination of non-ionic surfactant with cationic polymer had a significant effect on Cu-Pi nanoparticles. Conclusions Cu-Pi nanoparticles coated with PEG containing copolymer produced by Fessi method had a minimum average particle size, excellent polydispersity index and optimal zeta potential which fall within the acceptable limits of the study. This dual nanoparticulate drug delivery system appears to be promising to overcome oral bioavailability and cancer cell targeting limitations in the treatment of cancer. PMID:23569859

Moorthi, C; Krishnan, Kiran; Manavalan, R; Kathiresan, K

2012-01-01

246

A survey of place-exchange reaction for the preparation of water-soluble gold nanoparticles.  

PubMed

Water-soluble gold nanoparticles (AuNPs) have gained considerable attention because they offer a myriad of potential applications, especially in the fields of biology and medicine. One method to prepare such gold nanoparticles is through the well-known Murray place-exchange reaction. In this method, precursor gold nanoparticles, bearing labile ligands and with very good size distribution, are synthesized first, and then reacted with a large excess of the desired ligand. We report a comparison of the reactivity of several known precursor gold nanoparticles (citrate-stabilized, pentanethiol-stabilized, tetraoctylammonium bromide-stabilized, and 4-dimethylaminopyridine-stabilized) to several biologically relevant ligands, including amino acids, peptides, and carbohydrates. We found that citrate-stabilized and 4-dimethylaminopyridine-stabilized gold nanoparticles have broader reactivities than the other precursors studied. Citrate-stabilized gold nanoparticles are more versatile precursors because they can be prepared in a wide range of sizes and are very stable. The hydrophobic pentane-stabilized gold nanoparticles made them "inert" toward highly water-soluble ligands. Tetraoctylammonium bromide-stabilized gold nanoparticles exhibited selective reactivity, especially for small, unhindered and amphiphilic ligands. Depending on the desired ligand and size of AuNPs, a judicious selection of the available precursors can be made for use in place-exchange reactions. In preparing water-soluble AuNPs with biologically relevant ligands, the nature of the incoming ligand and the size of the AuNP should be taken into account in order to choose the most suitable place-exchange procedure. PMID:23149107

Briñas, Raymond P; Maetani, Micah; Barchi, Joseph J

2013-02-15

247

ZnFe 2O 4 nanoparticles for ferrofluids: A combined XANES and XRD study  

Microsoft Academic Search

A soft-chemistry method is used to synthesize zinc ferrite nanoparticles to prepare a magnetic fluid. We investigate here their internal structure by X-ray Absorption Near Edge Spectroscopy (XANES) and X-Ray Diffraction (XRD). A cross analysis of XANES and Rietveld refinement of XRD spectra shows non-equilibrium site occupancy with respect to bulk zinc ferrite, suggesting a cation redistribution that enhances the

J. A. Gomes; G. M. Azevedo; J. Depeyrot; J. Mestnik-Filho; G. J. da Silva; F. A. Tourinho; R. Perzynski

2011-01-01

248

Cellular uptake of ?-carotene from protein stabilized solid lipid nanoparticles prepared by homogenization-evaporation method.  

PubMed

With a homogenization-evaporation method, ?-carotene (BC) loaded nanoparticles were prepared with different ratios of food-grade sodium caseinate (SC), whey protein isolate (WPI), or soy protein isolate (SPI) to BC and evaluated for their physiochemical stability, in vitro cytotoxicity, and cellular uptake by Caco-2 cells. The particle diameters of the BC loaded nanoparticles with 0.75% SC or 1.0% WPI emulsifiers were 75 and 90 nm, respectively. Mean particle diameters of three BC loaded nanoparticle nanoemulsions increased less than 10% at 4 °C while they increased more at 25 °C (10-76%) during 30 days of storage. The oxidative stability of BC loaded nanoparticles encapsulated by proteins decreased in the following order: SC > WPI > SPI. The retention rates of BC in nanoparticles were 63.5%, 60.5%, and 41.8% for SC, WPI, and SPI, respectively, after 30 days of storage at 25 °C. The BC's chemical stability was improved by increasing the concentration of protein. Both the rate of particle growth and the total BC loss at 25 °C were larger than at 4 °C. The color of BC loaded nanoparticles decreased with increasing storage in the dark without oxygen, similar to the decrease in BC content of nanoparticles at 4 and 25 °C. Almost no cytotoxicity due to BC loaded nanoparticles cellular uptake was observed, especially when diluted 10 times or more. The uptake of BC was significantly improved through nanoparticle delivery systems by 2.6-, 3.4-, and 1.7-fold increase, respectively, for SC, WPI, and SPI, as compared to the free BC. The results of this study indicate that protein stabilized, BC loaded nanoparticles can improve stability and uptake of BC. PMID:24422504

Yi, Jiang; Lam, Tina I; Yokoyama, Wallace; Cheng, Luisa W; Zhong, Fang

2014-02-01

249

Boronic Acid functionalized core-shell polymer nanoparticles prepared by distillation precipitation polymerization for glycopeptide enrichment.  

PubMed

The boronic acid-functionalized core-shell polymer nanoparticles, poly(N,N-methylenebisacrylamide-co-methacrylic acid)@4-vinylphenylboronic acid (poly(MBA-co-MAA)@VPBA), were successfully synthesized for enriching glycosylated peptides. Such nanoparticles were composed of a hydrophilic polymer core prepared by distillation precipitation polymerization (DPP) and a boronic acid-functionalized shell designed for capturing glycopeptides. Owing to the relatively large amount of residual vinyl groups introduced by DPP on the core surface, the VPBA monomer was coated with high efficiency, working as the shell. Moreover, the overall polymerization route, especially the use of DPP, made the synthesis of nanoparticles facile and time-saving. With the poly(MBA-co-MAA)@VPBA nanoparticles, 18?glycopeptides from horseradish peroxidase (HRP) digest were captured and identified by MALDI-TOF mass spectrometric analysis, relative to eight glycopeptides enriched by using commercially available meta-aminophenylboronic acid agarose under the same conditions. When the concentration of the HRP digest was decreased to as low as 5?nmol, glycopeptides could still be selectively isolated by the prepared nanoparticles. Our results demonstrated that the synthetic poly(MBA-co-MAA)@VPBA nanoparticles might be a promising selective enrichment material for glycoproteome analysis. PMID:22707097

Qu, Yanyan; Liu, Jianxi; Yang, Kaiguang; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

2012-07-16

250

Silk fibroin nanoparticles prepared by electrospray as controlled release carriers of cisplatin.  

PubMed

To maintain the anti-tumor activity of cis-dichlorodiamminoplatinum (CDDP) while avoiding its cytotoxicity and negative influence on normal tissue, CDDP-loaded silk fibroin nanoparticles approximately 59nm in diameter were successfully prepared by electrospray without using organic solvent. CDDP was incorporated into nanoparticles through metal-polymer coordination bond exchange. In vitro release tests showed that the cisplatin in the nanoparticles could be slowly and sustainably released for more than 15days. In vitro anti-cancer experiments and intracellular Pt content testing indicated that CDDP-loaded silk fibroin nanoparticles were easily internalized by A549 lung cancer cells, transferring CDDP into cancer cells and then triggering their apoptosis. In contrast, the particles were not easily internalized by L929 mouse fibroblast cells and hence showed weaker cell growth inhibition. The CDDP-loaded silk fibroin nanoparticles showed sustained and efficient killing of tumor cells but weaker inhibition of normal cells. In general, this study provides not only a novel method for preparing CDDP-loaded silk fibroin nanoparticles but also a new carrier system for clinical therapeutic drugs against lung cancers and other tumors. PMID:25280693

Qu, Jing; Liu, Yu; Yu, Yanni; Li, Jing; Luo, Jingwan; Li, Mingzhong

2014-11-01

251

Epigallocatechin-3-gallate-capped Ag nanoparticles: preparation and characterization.  

PubMed

We used an aqueous leaf extract of Camellia sinensis to synthesize Ag nanoparticles (AgNPs). A layer of ca. 6 nm around a group of the AgNPs in which the inner layer is bound to the AgNPs surface via the hydroxyl groups of catechin has been observed. TEM analysis of AgNPs showed the formation of truncated triangular nanoplates and/or nanodisks and spherical with some irregular-shaped polydispersed nanoparticles in absence and presence of shape-directing cetyltrimethylammonium bromide. The polyphenolic groups of epigallocatechin-3-gallate (EGCG) are responsible for the rapid reduction of Ag(+) ions into metallic Ag(0). The free -OH groups are able to stabilize AgNPs by the interaction between the surface Ag atoms of AgNPs and oxygen atoms of EGCG molecules. PMID:24297160

Hussain, Shokit; Khan, Zaheer

2014-07-01

252

Preparation of ZnO nanoparticles in a reverse micellar system and their photoluminescence properties.  

PubMed

ZnO nanoparticles with spherical morphology and narrow size distribution were obtained by calcination of Zn(OH)2 nanoparticles, which were prepared in a polyethylene glycol mono-4-nonylphenyl ether (NP-5)/cyclohexane reverse micellar system and incorporated into polyurea (PUA) via an in situ polymerization of hexamethylene diisocyanate (HDI). The resulting ZnO nanoparticles demonstrated a near-UV emission and a green emission, the intensity ratio of which depended on calcination conditions. For the nanoparticles studied, the calcination atmosphere influenced remarkably the photoluminescence properties such as intensity ratio of the near-UV emission to green emission, rather than the size, morphology, and crystallinity of the ZnO nanoparticles. The green emission decreased by calcination in O2 flow but increased by calcination in N2 flow, as compared with the case calcined in air flow. This finding suggests that the green emission is enhanced with the increase of the number of oxygen vacancies of the ZnO nanoparticles and thus the photoluminescence properties of the nanoparticles were successfully controlled by the calcination condition, without changing the size and morphology. PMID:15752800

Hirai, Takayuki; Asada, Yoko

2005-04-01

253

Third order optical nonlinearity and diffraction pattern of Ni nanoparticles prepared by laser ablation  

NASA Astrophysics Data System (ADS)

In this article we studied all-optical Kerr effect of Ni nanoparticles immersed in ethanol using z-scan method. The nanoparticles were prepared by high frequency pulsed laser ablation. UV-Visible optical absorption spectroscopy and SEM observation were employed for characterization and studying the morphology of Ni nanoparticles. Analysis of scanning electron microscopy (SEM) images showed that the synthesized nanoparticles shape were dominantly spherical, varying from 19 nm to 40 nm for 1 mJ pulse energy. The nonlinear absorption and refraction indices were measured using open- and closed-aperture z-scan techniques, with both CW and pulsed irradiations. In both regimes results were studied. Furthermore, diffraction rings pattern as a result of nonlinear refraction was observed. We suggested an opportunity to form a new nonlinear-optical media for nonlinear optical applications.

Alikhani, S.; Tajalli, H.; Koushki, E.

2013-01-01

254

Nanoparticles based on albumin: preparation, characterization and the use for 5-flurouracil delivery.  

PubMed

The aim of the study was to formulate and evaluate nanoparticles based on albumin to deliver 5-fluorouracil. The nanoparticles were prepared by coacervation method. The nanoparticles were characterized for particle size, surface charge, size distribution and drug loading capacity. The drug loading capacity varied from 4.22% to 19.8% (w/w). The mean particle size was 141.9 nm and surface charge was -30.3 mV. The drug loaded particles exerted a bi-phasic release pattern with an initial burst effect followed by a sustained release in pH 7.4 phosphate buffer. The drug release was first order diffusion controlled and the mechanism was Fickian. The drug loaded nanoparticles showed superior cytotoxicity when compared to the free drug. PMID:22820011

Wilson, Barnabas; Ambika, T V; Patel, R Dharmesh Kumar; Jenita, Josephine Leno; Priyadarshini, S R B

2012-12-01

255

Preparation of AgX (X = Cl, I) nanoparticles using ionic liquids  

NASA Astrophysics Data System (ADS)

Nanoparticles of silver halides have been prepared by mixing silver halide powder with a single liquid phase consisting of an ionic liquid, isooctane, n-decanol and water. Much higher nanoparticle concentrations may be formed with ionic liquids using this new simple method than are found with conventionally applied surfactants. This method also emphasizes the applicability of ionic liquids as versatile components in microemulsions and as solvents for the synthesis of nanomaterials. The effect on the nanoparticles of changing the composition of the liquid mixtures and the nature of the ionic liquid is analysed. High nanoparticle concentrations were only found with chloride based ionic liquids, indicating the importance of the ionic liquid anion in the mechanism of the reaction.

Rodil, Eva; Aldous, Leigh; Hardacre, Christopher; Lagunas, M. Cristina

2008-03-01

256

Preparation and characterization of 6-mercaptopurine-coated magnetite nanoparticles as a drug delivery system  

PubMed Central

Background Iron oxide nanoparticles are of considerable interest because of their use in magnetic recording tape, ferrofluid, magnetic resonance imaging, drug delivery, and treatment of cancer. The specific morphology of nanoparticles confers an ability to load, carry, and release different types of drugs. Methods and results We synthesized superparamagnetic nanoparticles containing pure iron oxide with a cubic inverse spinal structure. Fourier transform infrared spectra confirmed that these Fe3O4 nanoparticles could be successfully coated with active drug, and thermogravimetric and differential thermogravimetric analyses showed that the thermal stability of iron oxide nanoparticles coated with chitosan and 6-mercaptopurine (FCMP) was markedly enhanced. The synthesized Fe3O4 nanoparticles and the FCMP nanocomposite were generally spherical, with an average diameter of 9 nm and 19 nm, respectively. The release of 6-mercaptopurine from the FCMP nanocomposite was found to be sustained and governed by pseudo-second order kinetics. In order to improve drug loading and release behavior, we prepared a novel nanocomposite (FCMP-D), ie, Fe3O4 nanoparticles containing the same amounts of chitosan and 6-mercaptopurine but using a different solvent for the drug. The results for FCMP-D did not demonstrate “burst release” and the maximum percentage release of 6-mercaptopurine from the FCMP-D nanocomposite reached about 97.7% and 55.4% within approximately 2,500 and 6,300 minutes when exposed to pH 4.8 and pH 7.4 solutions, respectively. By MTT assay, the FCMP nanocomposite was shown not to be toxic to a normal mouse fibroblast cell line. Conclusion Iron oxide coated with chitosan containing 6-mercaptopurine prepared using a coprecipitation method has the potential to be used as a controlled-release formulation. These nanoparticles may serve as an alternative drug delivery system for the treatment of cancer, with the added advantage of sparing healthy surrounding cells and tissue. PMID:24106420

Dorniani, Dena; Hussein, Mohd Zobir bin; Kura, Aminu Umar; Fakurazi, Sharida; Shaari, Abdul Halim; Ahmad, Zalinah

2013-01-01

257

Optical properties of CdSe nanoparticle films prepared by chemical deposition and sol gel methods  

NASA Astrophysics Data System (ADS)

CdSe nanoparticle films were prepared by chemical solution deposition and formation in a silica sol-gel matrix. X-ray powder diffraction and transmission electron microscope measurements confirmed a cubic crystallographic structure of the nanoparticles, with mean diameter varying from 4 to 20 nm. The absorption and photoluminescence spectra of the smaller crystals were strongly blue-shifted due to size quantization. This Letter focuses on the study of a non-excitonic emission band, which can be associated with surface states. The results indicate that this band involves the recombination between shallow trapped electrons and deep trapped holes, with a donor-acceptor-like recombination and are analyzed in terms of the configuration coordinate model. The CdSe nanoparticles prepared by the two different methods showed essentially the same optical behavior.

Lifshitz, E.; Dag, I.; Litvin, I.; Hodes, G.; Gorer, S.; Reisfeld, R.; Zelner, M.; Minti, H.

1998-05-01

258

Preparation of iron oxide nanoparticles from FeCl3 solid powder using microemulsions  

NASA Astrophysics Data System (ADS)

Nanoparticles of iron oxide were prepared by subjecting iron chloride powder to (w/o) microemulsions consisting of sodium bis(2-ethylhexyl) sulfosuccinate (AOT), isooctane and water. FeCl3 was first dissolved in the water pools of the microemulsion, and then reacted with NaOH added as an aqueous solution to form iron oxide. The amount of NaOH solution was limited so that single microemulsion phase is obtained. This technique serves as an in-situ nanoparticle preparation technique aimed at minimizing particle aggregation associated with particle transportation to required sites. In this study, the effects of AOT concentration and water to AOT mole ratio on the nanoparticle size were investigated. UV/Vis spectrophotometry and transmission electron microscopy (TEM) were used to measure the particle size distribution.

Nassar, Nashaat; Husein, Maen

2006-05-01

259

Preparation and thermoelectric properties of sulfur doped Ag2Te nanoparticles via solvothermal methods.  

PubMed

In this work, n-type Ag(2)Te nanoparticles are prepared by a solvothermal approach with uniform and controllable sizes, e.g. 5-15 nm. The usage of dodecanethiol during the synthesis effectively introduces sulfur doping into the sample, which optimizes the charge carrier concentration of the nanoparticles to >1 × 10(20) cm(-3). This allows us to achieve the desired electrical resistivities of <5 × 10(-6)? m. It is demonstrated that Ag(2)Te particles prepared by this solvothermal process can exhibit high ZT values, e.g. 15 nm Ag(2)Te nanoparticles with effective sulphur doping show a maximum ZT value of ~0.62 at 550 K. PMID:22652813

Zhou, Wenwen; Zhao, Weiyun; Lu, Ziyang; Zhu, Jixin; Fan, Shufen; Ma, Jan; Hng, Huey Hoon; Yan, Qingyu

2012-07-01

260

Preparation of curcumin-loaded poly(ester amine) nanoparticles for the treatment of anti-angiogenesis.  

PubMed

The aim of this study was to prepare curcumin loaded poly(ester amine) nanoparticles and enhance their hydrophilicity and treatment efficacy on anti-angiogenesis zebra fish model. Poly(ester amine) (PEA) copolymer was synthesized in this study. The curcumin-loaded PEA nanoparticles were prepared through double emulsion-solvent evaporation technique. The average particle size of obtained nanoparticles was about 100 nm. The zeta potential of prepared nanoparticles was about 35.8+/-2.4 mV. Transmission electron microscopy demonstrated a narrow size distribution with in vitro release profile demonstrating in vitro slow release of curcumin from the PEA nanoparticles. The in vitro cytotoxicity of the curcumin encapsulated PEA nanoparticles nearly had the same tendency of cytotoxic activity in vitro with free curcumin on tumor cells. In vitro cellular uptake of the curcumin-loaded nanoparticles demonstrated in Hela cells demonstrated that this kind of nanoparticles can be a promising candidate as a drug delivery system to cancer cells. The Cur/PEA nanoparticles more efficiently inhibited angiogenesis (in vivo) in transgenic zebra fish model and Alginate-encapsulated tumor cells than free curcumin. No mortality or significant lesions were observed from histopathological study of the major organs. From our results, we can conclude that the prepared PEA nanoparticles are an efficient curcumin drug delivery system for anti-angiogenesis therapy. PMID:24734515

Ding, Qiuxia; Niu, Ting; Yang, Yi; Guo, Qingfa; Luo, Feng; Qian, Zhiyong

2014-04-01

261

Two modelling data analytical methods applied to optimise the preparation of norcantharidin chitosan nanoparticles  

Microsoft Academic Search

In our study, the non-linear regression model and artificial neural networks (ANNs) were used to optimise the preparation of the loading norcantharidin chitosan nanoparticles (NPs) by ionic cross-linkage. Two major indexes, the particle size and the entrapment efficiency of the drug vehicles were synchronously optimised according to the normalised value calculated referring to the weights of the indexes and factors.

Wei Zhang; Yang Liu; Xiao-Yan Chen; Yong-Yan Bei; Jing-Yu Xu; Wen-Juan Wang; Xue-Nong Zhang; Qiang Zhang

2010-01-01

262

Preparation of high concentration of silver colloidal nanoparticles in layered laponite sol  

Microsoft Academic Search

The synthesis and characterization of silver colloidal nanoparticles by chemical reduction of silver ions in the presence of laponite using sodium borohydride (NaBH4) as the reducing agent are described. Laponite is used to prevent the growth and aggregation of particles to give stable high concentration of silver colloidal particles with a narrow size distribution. The optimum experimental condition for preparing

Jie Liu; Jung-Baek Lee; Dong-Hwan Kim; Youhyuk Kim

2007-01-01

263

Stability, size and optical properties of silver nanoparticles prepared by laser ablation in different carrier media  

Microsoft Academic Search

We studied the effects of the surrounding liquid environment on the size and optical properties of silver nanoparticles prepared by laser ablation by a pulsed Nd:YAG laser operated at 1064 nm. The silver targets used were kept in acetone, water and ethanol. TEM observations and optical extinction were employed for characterization of particle size, shape and optical properties, respectively. Nano

R. M. Tilaki; A. Iraji Zad; S. M. Mahdavi

2006-01-01

264

Preparation and Ultrafast Optical Characterization of Metal and Semiconductor Colloidal NanoParticles  

Microsoft Academic Search

The ultrafast dynamics of photoinduced electrons in several metal and semiconductor colloidal nano-particle systems are characterized using femtosecond laser spectroscopy. Various preparation methods are used and, in several cases, modified for making particles with long-term stability and narrow and controllable size distributions. The particle size and size distribution are determined using transmission electron microscopy and electronic absorption spectroscopy. For aqueous

B. A. Smith; D. M. Waters; A. E. Faulhaber; M. A. Kreger; T. W. Roberti; J. Z. Zhang

1997-01-01

265

Stability, size and optical properties of silver nanoparticles prepared by laser ablation in different carrier media  

Microsoft Academic Search

We studied the effects of the surrounding liquid environment on the size and optical properties of silver nanoparticles prepared by laser ablation by a pulsed Nd:YAG laser operated at 1064 nm. The silver targets used were kept in acetone, water and ethanol. TEM observations and optical extinction were employed for characterization of particle size, shape and optical properties, respectively. Nano silver

R. M. Tilaki; A. Iraji zad; S. M. Mahdavi

2006-01-01

266

Experimental The average size of the silver nanoparticles, prepared by the method of Kor-  

E-print Network

Experimental The average size of the silver nanoparticles, prepared by the method of Kor- gel, with approximate molecular weight of 900 000, was then added to 0.5 mg of these silver nanocrystals in a vial, and radically improved photochemical reactors.[1±6] Colloidal self-assembly has been suggested as an efficient

Braun, Paul

267

Preparation and characterization of polyelectrolyte-coated gold nanoparticles.  

PubMed

Gold nanoparticles of 5 nm diameter, stabilized by 4-(dimethylamino)pyridine (DMAP), were coated with poly(sodium 4-styrene sulfonate) (PSS) via electrostatic self-assembly. The suspension stability, monitored by the gold surface plasmon band (SPB), was studied by varying the pH, the PSS chain length, and PSS concentration. Enhanced stability is obtained at pH 10 (above the pKa of DMAP) when the polymer chain length matches or exceeds the particle circumference. Solid state 13C NMR was used to determine the presence of DMAP and polymers after subsequent deposition of weak and strong polycations: poly(allylamine hydrochloride) (PAH) and poly(diallyldimethylammonium chloride) (PDADMAC). At pH 10, DMAP remains associated with the nanoparticle after the first PSS layer has been formed. When PAH or PDADMAC are subsequently added at pH 4.5, DMAP is expelled, the suspensions remain stable, and zeta potential values indicate complete charge reversal. In the case of PDADMAC, however, the first layer of PSS is not fully retained. When PDADMAC is added at pH 10, DMAP and the first PSS layer are retained but lower zeta potentials and a higher SPB shift indicate a degraded stability. For PAH addition at pH 9.5, both DMAP and PSS are expelled and the suspension becomes unstable. These differences in stability of the multilayer components and the nanoparticle suspension are rationalized in terms of chain flexibility, polymer charge density, and the ability of the polymer functional groups to directly interact with the gold surface. PMID:18229959

Dorris, Annie; Rucareanu, Simona; Reven, Linda; Barrett, Christopher J; Lennox, R Bruce

2008-03-18

268

Microbial preparation of metal-substituted magnetite nanoparticles.  

PubMed

A microbial process that exploits the ability of iron-reducing microorganisms to produce copious amounts of extra-cellular metal (M)-substituted magnetite nanoparticles using akaganeite and dopants of dissolved form has previously been reported. The objectives of this study were to develop methods for producing M-substituted magnetite nanoparticles with a high rate of metal substitution by biological processes and to identify factors affecting the production of nano-crystals. The thermophilic and psychrotolerant iron-reducing bacteria had the ability to form M-substituted magnetite nano-crystals (M(y)Fe(3-y)O(4)) from a doped precursor, mixed-M iron oxyhydroxide, (M(x)Fe(1-x)OOH, x< or =0.5, M is Mn, Zn, Ni, Co and Cr). Within the range of 0.01< or =x< or =0.3, using the mixed precursor material enabled the microbial synthesis of more heavily substituted magnetite compared to the previous method, in which the precursor was pure akaganeite and the dopants were present as soluble metal salts. The mixed precursor method was especially advantageous in the case of toxic metals such as Cr and Ni. Also this new method increased the production rate and magnetic properties of the product, while improving crystallinity, size control and scalability. PMID:17532071

Moon, Ji-Won; Roh, Yul; Lauf, Robert J; Vali, Hojatollah; Yeary, Lucas W; Phelps, Tommy J

2007-07-01

269

The effect of energy density on yield of silicon nanoparticles prepared by pulsed laser ablation in liquid  

NASA Astrophysics Data System (ADS)

The effect of energy density on the yield of silicon nanoparticles was studied. Silicon nanoparticles were prepared by laser ablation in ethanol. The yield of nanoparticles was calculated and its results indicate that high energy density led to more nanoparticles production. Particle size was also affected by varying energy density. From TEM images, higher energy density resulted in smaller nanoparticles, which can be explained by nucleation and growth theory. Photoluminescence spectra revealed blue shift of emission peak at high energy density supporting TEM results. Silicon peak was detected by EDS analysis along with oxygen. This means oxidation of silicon might occur within the sample.

Chewchinda, P.; Odawara, O.; Wada, H.

2014-10-01

270

Preparation of ceria nanoparticles embedded in PMMA using sonochemical technique  

Microsoft Academic Search

Homogeneous distribution of semicrystalline ceria in polymethylmethacrylate has been reported. The ceria has been prepared by sonochemical method, in situ. The as-prepared composite was characterized by XRD, TEM, DSC and TGA methods. An average size of the ceria is found to be ?5 nm by XRD and TEM measurements. The photonic band gap has been measured as 3.55 eV, which is in

Vijaya K. Rangari; D. N. Srivastava; A. Gedanken

2006-01-01

271

Preparation and characterization of Tamoxifen citrate loaded nanoparticles for breast cancer therapy  

PubMed Central

Background Four formulations of Tamoxifen citrate loaded polylactide-co-glycolide (PLGA) based nanoparticles (TNPs) were developed and characterized. Their internalization by Michigan Cancer Foundation-7 (MCF-7) breast cancer cells was also investigated. Methods Nanoparticles were prepared by a multiple emulsion solvent evaporation method. Then the following studies were carried out: drug-excipients interaction using Fourier transform infrared spectroscopy (FTIR), surface morphology by field emission scanning electron microscopy (FESEM), zeta potential and size distribution using a Zetasizer Nano ZS90 and particle size analyzer, and in vitro drug release. In vitro cellular uptake of nanoparticles was assessed by confocal microscopy and their cell viability (%) was studied. Results No chemical interaction was observed between the drug and the selected excipients. TNPs had a smooth surface, and a nanosize range (250–380 nm) with a negative surface charge. Drug loadings of the prepared particles were 1.5%±0.02% weight/weight (w/w), 2.68%±0.5% w/w, 4.09%±0.2% w/w, 27.16%±2.08% w/w for NP1–NP4, respectively. A sustained drug release pattern from the nanoparticles was observed for the entire period of study, ie, up to 60 days. Further, nanoparticles were internalized well by the MCF-7 breast cancer cells on a concentration dependent manner and were present in the cytoplasm. The nucleus was free from nanoparticle entry. Drug loaded nanoparticles were found to be more cytotoxic than the free drug. Conclusion TNPs (NP4) showed the highest drug loading, released the drug in a sustained manner for a prolonged period of time and were taken up well by the MCF-7 breast cancer cell line in vitro. Thus the formulation may be suitable for breast cancer treatment due to the good permeation of the formulation into the breast cancer cells. PMID:25028549

Maji, Ruma; Dey, Niladri Shekhar; Satapathy, Bhabani Sankar; Mukherjee, Biswajit; Mondal, Subhasish

2014-01-01

272

Controlled oxidation of FeCo magnetic nanoparticles to produce faceted FeCo/ferrite nanocomposites for rf heating applications  

E-print Network

for rf heating applications K. N. Collier,1,2 N. J. Jones,1 K. J. Miller,1 Y. L. Qin,1 D. E. Laughlin,1 for polydisperse FeCo magnetic nanoparticles MNPs synthesized using an induction plasma torch. X-ray diffraction the FeCo core and oxide shell. We show HRTEM images of MNP chaining and compare the rf heating of samples

Laughlin, David E.

273

Nanodimensional spinel NiFe2O4 and ZnFe2O4 ferrites prepared by soft mechanochemical synthesis  

NASA Astrophysics Data System (ADS)

NiFe2O4 and ZnFe2O4 ferrites have been prepared by soft mechanochemical synthesis. The formation of spinel phase and crystal structure of sintered powders were analyzed by X-ray diffraction, Raman spectroscopy, and transmission microscopy. In order to confirm phase formation and cation arrangement, Mössbauer measurements were done. Investigation of the magnetization as a function of magnetic field confirms an expected change of the degree of inversion in the spinel structure with the sintering. The electrical DC/resistivity/conductivity was measured in the temperature range of 298-423 K. Impedance spectroscopy was performed in the wide frequency range (100 Hz-10 MHz) at different temperatures.

Lazarevi?, Ž.; Jovaleki?, ?.; Milutinovi?, A.; Sekuli?, D.; Ivanovski, V. N.; Re?nik, A.; Ceki?, B.; Rom?evi?, N. Ž.

2013-05-01

274

Water-repellent coatings prepared by modification of ZnO nanoparticles.  

PubMed

Superhydrophobic coatings with a static water contact angle (WCA)>150° were prepared by modifying ZnO nanoparticles with stearic acid (ZnO@SA). ZnO nanoparticles of size ?14nm were prepared by solution combustion method. X-ray diffraction (XRD) studies reveal that as prepared ZnO has hexagonal wurtzite structure whereas the modified coatings convert to zinc stearate. Field emission scanning electron micrographs (FE-SEM) show the dual morphology of the coatings exhibiting both particles and flakes. The flakes are highly fluffy in nature with voids and nanopores. Fourier transformed infrared (FTIR) spectrum shows the stearate ion co-ordinates with Zn(2+) in the bidentate form. The surface properties such as surface free energy (?(p)) and work of adhesion (W) of the unmodified and modified ZnO coatings have been evaluated. The electron paramagnetic resonance (EPR) spectroscopy reveals that surface defects play a major role in the wetting behavior. PMID:22575349

Chakradhar, R P S; Dinesh Kumar, V

2012-08-01

275

Improvement of Coercivity in Cobalt-Doped Anatase TiO2 Nanoparticles Hydrothermally Prepared  

NASA Astrophysics Data System (ADS)

Anatase Ti1-xCoxO2 nanoparticles were prepared by a hydrothermal process at 180 °C. Ferromagnetic hysteresis loops of the as-prepared samples were measured at room temperature. The Ti1-xCoxO2 (x = 0.0376) powder shows coercivity up to 700 Oe, which is the highest value reported for anatase Ti1-xCoxO2. X-ray diffraction (XRD), transmission electron microscopy (TEM) and magnetic measurement results provided evidence that Co was incorporated into TiO2 lattice. Combined with the fact that the preparation was carried out in an oxidized environment starting from cobalt (II) in the oxidized state, it is suggested that the homogeneous doping of Co into the lattice of anatase should be responsible for the improvement of coercivity in anatase Ti1-xCoxO2 nanoparticles.

Wu, Mingzai; Xiong, Ying; Jiang, Nan; Qi, Hai Ping; Chen, Qianwang

276

Chitosan-poly (lactide-co-glycolide) (CS-PLGA) nanoparticles containing metformin HCl: Preparation and in vitro evaluation.  

PubMed

In this study, the preparation and in vitro characterisation of metformin HCl-loaded CS-PLGA nanoparticles (NPs) were aimed. The prepared nanoparticles (blank nanoparticles (C-1), 50 mg of metformin HCl loaded nanoparticles (C-2) and 75 mg of metformin HCl loaded nanoparticles (C-3) ranged in size from 506.67±13.61 to 516.33±16.85 nm and had surface charges of 22.57±1.21 to 32.37±0.57 mV. Low encapsulation efficiency was observed for both nanoparticle formulations due to the leakage of metformin HCl to the external medium during preparation of nanoparticles. Nanoparticle formulations showed highly reproducible drug release profiles. ~20% of metformin HCl was released within 30 minutes and approximately 98% of the loaded metformin HCl was released at 144 hours in a phosphate buffer (PB; pH 6.8). No statistically significant difference was noted between the in vitro release profiles of the nanoparticles (C-2 and C-3) containing metformin HCl. Also, nanoparticles were characterised using FT-IR and DSC. PMID:25362616

Gundogdu, Nuran; Cetin, Meltem

2014-11-01

277

The effect of annealing on phase evolution, microstructure and magnetic properties of Mn substituted CoFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese substituted CoFe2O4 nanoparticles has been prepared by a simple evaporation method and auto combustion method. The role of annealing temperature on phase, particle size and morphology of Mn-Co ferrite nanoparticles were determined by X-ray diffraction, and transmission electron microscopy (TEM). The lowest size of particles (~3 nm) is obtained by auto combustion method. The annealing effect creates a vital change in magnetic properties which is studied by using vibrating sample magnetometer (VSM). These spinel ferrites are decomposed to ?-Fe2O3 after annealing above 550 °C in air. However, ?-Fe2O3 phase was slowly vanished after ferrites annealing above 900 °C. The effect of this secondary phase on the structural and magnetic properties of Mn substituted cobalt ferrite nanoparticles is also discussed.

Ranjith Kumar, E.; Jayaprakash, R.; Prakash, T.

2014-05-01

278

A facile water-based process for preparation of stabilized Bi nanoparticles  

SciTech Connect

Stabilized bismuth nanoparticles have been prepared by reducing bismuth chloride with hydrazine hydrate in the presence of sodium oleate under a facile water-based process. The obtained samples are investigated by X-ray diffraction, transmission electron microscopy (TEM) and differential thermal analysis and thermogravimetry (DTA/TG). The present results indicate that the bismuth nanoparticles are spherical, small diameter and in a high purity. In addition, measurement of water contact angle indicates that Bi samples are hydrophobic, which gives defense to samples from further oxidation, samples are steady in 6 months without obvious oxidation.

Wang Yi [College of Chemistry, Jilin University, Changchun 130023 (China); Department of Chemistry, Yanbian University, Yanji 133000 (China); Zhao Jingzhe [Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)], E-mail: zhaojz@mail.jlu.edu.cn; Zhao Xu; Tang Lanqin; Li Yunling; Wang Zichen [College of Chemistry, Jilin University, Changchun 130023 (China)

2009-01-08

279

Preparation and optical properties of cobalt doped lithium tetraborate nanoparticles  

NASA Astrophysics Data System (ADS)

Lithium tetraborate doped with cobalt ions of different concentrations were synthesized by chemical method and characterized by X-ray. Field emission scanning electron microscopy reveals the spherical morphology of the nanoparticles and the average particle size is estimated to be 50-110 nm. UV-Vis studies show the inclusion of Co2+ and the lithium-vacancy pair production. The samples are completely transparent in the visible region and having absorption peak (220 nm) in UV region. Nonlinear optical studies indicate the suitability of pure and Co2+ doped samples for low power optical limiting and frequency doubling applications. From the Z-scan technique, the nonlinear optical parameters such as nonlinear refractive index, nonlinear absorption and nonlinear optical susceptibility are estimated as 10-8 cm2/W, 10-2 cm/W and 10-5 esu respectively.

Dhanuskodi, S.; Mohandoss, R.; Vinitha, G.

2014-07-01

280

Preparation of Y2O3:Eu3+ nanoparticles in reverse micellar systems and their photoluminescence properties.  

PubMed

Y2O3:Eu3+ phosphor nanoparticles (4-8 nm in size) with spherical morphology and narrow size distribution were obtained by calcination of composite Y-Eu hydroxide nanoparticles, which were prepared in sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane or polyethylene glycol mono-4-nonylphenyl ether (NP-5)/cyclohexane reverse micellar systems. This was achieved by the incorporation of the Y-Eu hydroxide nanoparticles into polyurea (PUA) via in situ polymerization of hexamethylene diisocyanate (HDI) in the reverse micellar solution and subsequent calcination of the resulting PUA materials. The emission intensity of the Y2O3:Eu3+ nanoparticles, prepared in the AOT/isooctane system, was significantly lower than that of the micrometer-size particles prepared in a homogeneous aqueous solution, since the calcined nanoparticles contained Na2SO4 impurity derived from the remaining AOT surfactant. The nanoparticles prepared in the NP-5/cyclohexane system, in contrast, showed higher emission intensity compared to the nanoparticles prepared in the AOT/isooctane system and longer luminescence lifetime compared to the micrometer-size particles prepared in the homogeneous aqueous solution. The photoluminescence intensity of Y2O3:Eu3+, prepared via the proposed process was found to decrease with decreasing the particle size. PMID:15271561

Hirai, Takayuki; Asada, Yoko; Komasawa, Isao

2004-08-15

281

Comparison study of the magnetic permeability and dc conductivity of Co-Ni-Li ferrite nanoparticles and their bulk counterparts  

NASA Astrophysics Data System (ADS)

The temperature dependence of relative permeability and dc electrical conductivity of nanosamples and their bulk counterparts of Co0.5Ni0.5-2xLixFe2+xO4 (from x=0.00 to 0.25 in step of 0.05) was investigated. The values of the relative permeability of the nano-samples are lower than their bulk counterparts as a result of porous and nano-grained structure besides the effect of the larger volume of grain boundaries in the nanosamples. Moreover, the dc conductivity of the nanosamples is higher than their bulk counterparts. This is probable explained according to the shorter metal-oxygen bonding length and higher lattice vibrations of the nanosamples. Also, the values of the relative permeability of both nano and bulk samples exhibit stability over a considerable range of temperatures. This may make them useful in practical applications that require stability. All the nanosamples show high rising Curie temperature values with increasing the Li content up to the sample of x=0.15 thereafter a decrease of the Curie temperature occurs while the inverse behavior was observed in their bulk counterparts. The interpretation of these findings is explained in the discussion. Moreover, in general doping Co-Ni ferrites with Li ions improves their electrical and magnetic properties and this is clearly observed in the nanosample of x=0.15 which can be regarded as the most promising sample for microwave applications.

Assar, S. T.; Abosheiasha, H. F.; El Nimr, M. K.

2014-03-01

282

nanoparticles  

NASA Astrophysics Data System (ADS)

Undoped and Zn-doped TiO2 nanoparticles were synthesized by the sol gel method. The dopant (Zn) was taken at 0.1, 0.2, 0.5, 0.7, and 1.0 mol%. The initial precursors were titanium tetraisopropoxide and zinc acetate. The samples were characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and UV-vis diffuse reflectance. The photocatalytic activity of the prepared nanoparticles was studied by observing their role in degradation of two azo dyes, i.e., Eriochrome Black T and Methyl Red under UV-visible light. The results revealed that Zn-doped TiO2 nanoparticles exhibited better degradation as compared to undoped TiO2 nanoparticles. In this study, 0.7 mol% Zn-doped TiO2 showed highest photocatalytic activity. Doping of Zn allowed better separation of electron-hole pairs which results in increased oxidation and reduction reactions.

Singla, Pooja; Sharma, Manoj; Pandey, O. P.; Singh, K.

2014-07-01

283

Preparation of bicontinuous mesoporous silica and organosilica materials containing gold nanoparticles by co-synthesis method  

SciTech Connect

Catalytic activities of gold strongly depend on its particle size. It is necessary to have homogeneous distributions of small gold nanoparticles with diameters between 2 and 5 nm for excellent catalytic activities. In this study, gold-containing mesoporous silica materials were prepared by a co-synthesis method. The essence of this sol-gel co-synthesis method is to combine together neutral surfactant template synthesis of mesoporous silica materials with the introduction of metal ions via bifunctional silane ligands, so that the formation of mesostructures and metal-ion doping occur simultaneously. The formation of gold nanoparticles with size less than 5 nm inside mesoporous materials (HMS, MSU, and PMO) has been achieved by this co-synthesis sol-gel process. In addition, the effects of post-treatments, such as calcination and reduction, on pore structures and nanoparticle size distributions were also investigated.

Lee, Byunghwan [Korea Institute of Industrial Technology, ChonAn, Korea; Zhu, Haoguo [ORNL; Zhang, Zongtao [ORNL; Overbury, Steven {Steve} H [ORNL; Dai, Sheng [ORNL

2004-01-01

284

Preparation of gold nanoparticles using Salicornia brachiata plant extract and evaluation of catalytic and antibacterial activity  

NASA Astrophysics Data System (ADS)

The current study deals with the synthesis of gold nanoparticles (AuNPs) using Salicornia brachiata (Sb) and evaluation of their antibacterial and catalytic activity. The SbAuNPs showed purple color with a characteristic surface plasmon resonance peak at 532 nm. Scanning electron microscopy and transmission electron microscopy revealed polydispersed AuNPs with the size range from 22 to 35 nm. Energy dispersive X-ray and thin layer X-ray diffraction analysis clearly shows that SbAuNPs was pure and crystalline in nature. As prepared gold nanoparticles was used as a catalyst for the sodium borohydride reduction of 4-nitro phenol to 4-amino phenol and methylene blue to leucomethylene blue. The green synthesized nanoparticles exhibited potent antibacterial activity against the pathogenic bacteria, as evidenced by their zone of inhibition. In addition, we showed that the SbAuNPs in combination with the regular antibiotic, ofloxacin, exhibit superior antibacterial activity than the individual.

Ayaz Ahmed, Khan Behlol; Subramanian, Swetha; Sivasubramanian, Aravind; Veerappan, Ganapathy; Veerappan, Anbazhagan

2014-09-01

285

Structural and magnetic characterization of Co-Cu nanoparticles prepared by arc-discharge  

NASA Astrophysics Data System (ADS)

The structure and magnetic properties of the nanoparticles of immiscible system Co{20}Cu{80} prepared by means of arc-discharge, have been studied in detail. The diameters of the particles are about 20 ˜ 30 nm and a core/shell structure forms. The cores are Co-Cu solutions, which show some small Co precipitates, encapsulated with a shell of cupper oxide or cobalt oxide as observed by means of high-resolution transmission electron microscope (HRTEM) and energy dispersive X-ray (EDS). The loop shift in the hysteresis loop indicates the existence of the exchange bias between ferromagnetic and antiferromagnetic components at low temperatures. A block temperature about 180 K has been observed for as-deposited nanoparticles. For the annealed nanoparticles, the thermal magnetization at low temperatures is satisfied with Bloch's law.

You, Cai-Yin; Yang, Z. Q.; Xiao, Q. F.; Škorvánek, I.; Ková?, J.; Li, Z. J.; Liu, W.; Zhang, Z. D.

2004-10-01

286

Surface-modified antibacterial TiO 2/Ag + nanoparticles: Preparation and properties  

NASA Astrophysics Data System (ADS)

Studies were performed on surface modification of antibacterial TiO 2/Ag + nanoparticles by grafting ?-aminopropyltriethoxysilane (APS). The interfacial structure of the modified particles was characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis. The thickness of the surface layer was determined by using Auger electron spectroscopy (AES). The results show that APS is chemically bonded to the surface of antibacterial TiO 2/Ag + nanoparticles. Furthermore, the modified particles were mixed in PVC to prepare composites whose antibacterial property was investigated. The results suggest that surface modification has no negative effect on antibacterial activity of TiO 2/Ag + nanoparticles and PVC-TiO 2/Ag + composites exhibits good antibacterial property.

Cheng, Qilin; Li, Chunzhong; Pavlinek, Vladimir; Saha, Petr; Wang, Huanbing

2006-04-01

287

Preparation of Carvedilol Nanoparticles by Emulsification Method and Optimization of Drug Release: Surface Response Design vs Genetic Algorithm  

Microsoft Academic Search

The objectives of this research were production of Eudragit nanoparticles of carvedilol the anti-hypertension drug for enhancement its absorption and optimization of drug release. Nanoparticles were prepared by emulsification-solvent evaporation or diffusion methods. The statistical surface response design based on Box-Behnken model was applied to evaluate the effect of 4 variables each in 2 levels on specifications of nanoparticles. An

Jaleh Varshosaz; Elaheh Moazen; Milad Fathi

2012-01-01

288

An experimental assessment of toxic potential of nanoparticle preparation of heavy metals in streptozotocin induced diabetes.  

PubMed

Nanoparticle preparations of heavy metals have attracted enormous scientific and technological interest. Biologically produced nanoparticle preparations of heavy metals are elaborately described in traditional texts and being widely prescribed. The underlying interactions of nano preparations within the physiological fluids are key feature to understand their biological impact. In this perspective, we performed an experimental assessment of the toxicity potential of a marketed metallic preparation named Vasant Kusumakar Ras (VKR), wherein different heavy metals in composite form are reduced to nanoparticle size to produce the desired effect in diabetes and its complications. VKR (50mg/kg) was administered to Albino Wistar rats rendered diabetic using streptozotocin (90mg/kg) in 2 days old neonates. Anti-hyperglycemic effect was observed with VKR along with increased levels of plasma insulin. Renal variables including total proteins and albumin along with glomerular filtration rate were found to improve biochemically. The results were supplemented by effects on different inflammatory and growth factors like TNF-?, nitric oxide, TGF-? and VEGF. However, the results observed in kidney histopathology were not in accordance with the biochemical parameters. Inflammation observed in kidney was confirmed by immunostaining metallothionein, which was due to the accumulation of heavy metals. Furthermore, mercury accumulation in kidney further confirmed by autometallography, which activated mononuclear phagocyte system, which generated an immune response. This was further supported by increase in the extent of apoptosis in kidney tissues. In conclusion, nanoparticle preparations of heavy metals can be toxic to kidney if it is not regulated with respect to its surface chemistry and dosage. PMID:23790456

Gandhi, Sonia; Srinivasan, B P; Akarte, Atul Sureshrao

2013-11-01

289

Organic/Hybrid nanoparticles and single-walled carbon nanotubes: preparation methods and chiral applications.  

PubMed

Nanoparticles are molecular-sized solids with at least one dimension measuring between 1-100 nm or 10-1000 nm depending on the individual discipline's perspective. They are aggregates of anywhere from a few hundreds to tens of thousands of atoms which render them larger than molecules but smaller than bulk solids. Consequently, they frequently exhibit physical and chemical properties somewhere between. On the other hand, nanocrystals are a special class of nanoparticles which have started gaining attention recently owing to their unique crystalline structures which provide a larger surface area and promising applications including chiral separations. Hybrid nanoparticles are supported by the growing interest of chemists, physicists, and biologists, who are researching to fully exploit them. These materials can be defined as molecular or nano-composites with mixed (organic or bio) and inorganic components, where at least one of the component domain has a dimension ranging from a few Å to several nanometers. Similarly, and due to their extraordinary physical, chemical, and electrical properties, single-walled carbon nanotubes have been the subject of intense research. In this short review, the focus is mainly on the current well-established simple preparation techniques of chiral organic and hybrid nanoparticles as well as single-walled carbon nanotubes and their applications in separation science. Of particular interest, cinchonidine, chitosan, and ?-CD-modified gold nanoparticles (GNPs) are discussed as model examples for organic and hybrid nanoparticles. Likewise, the chemical vapor deposition method, used in the preparation of single-walled carbon nanotubes, is discussed. The enantioseparation applications of these model nanomaterials is also presented. Chirality 26:683-691, 2014. © 2014 Wiley Periodicals, Inc. PMID:24811353

Alhassen, Haysem; Antony, Vijy; Ghanem, Ashraf; Yajadda, Mir Massoud Aghili; Han, Zhao Jun; Ostrikov, Kostya Ken

2014-11-01

290

Preparation and Characterization of Gelatin Nanofibers Containing Silver Nanoparticles  

PubMed Central

Ag nanoparticles (NPs) were synthesized in formic acid aqueous solutions through chemical reduction. Formic acid was used for a reducing agent of Ag precursor and solvent of gelatin. Silver acetate, silver tetrafluoroborate, silver nitrate, and silver phosphate were used as Ag precursors. Ag+ ions were reduced into Ag NPs by formic acid. The formation of Ag NPs was characterized by a UV-Vis spectrophotometer. Ag NPs were quickly generated within a few minutes in silver nitrate (AgNO3)/formic acid solution. As the water content of formic acid aqueous solution increased, more Ag NPs were generated, at a higher rate and with greater size. When gelatin was added to the AgNO3/formic acid solution, the Ag NPs were stabilized, resulting in smaller particles. Moreover, gelatin limits further aggregation of Ag NPs, which were effectively dispersed in solution. The amount of Ag NPs formed increased with increasing concentration of AgNO3 and aging time. Gelatin nanofibers containing Ag NPs were fabricated by electrospinning. The average diameters of gelatin nanofibers were 166.52 ± 32.72 nm, but these decreased with the addition of AgNO3. The average diameters of the Ag NPs in gelatin nanofibers ranged between 13 and 25 nm, which was confirmed by transmission electron microscopy (TEM). PMID:24758929

Jeong, Lim; Park, Won Ho

2014-01-01

291

Tamoxifen citrate loaded solid lipid nanoparticles (SLN): preparation, characterization, in vitro drug release, and pharmacokinetic evaluation.  

PubMed

Solid lipid nanoparticles (SLN) were prepared by emulsification and high pressure homogenization technique and characterized by size analysis and differential scanning calorimetry. The influence of experimental factors such as homogenization pressure, time, and surfactant concentration on the nanoparticle size and distribution were investigated to optimize the formulation. Homogenization at 15,000 psi for 3 cycles was found to be optimum and resulted in smaller sized nanoparticles. In case of tristearin SLN (TSSLN), tripalmitin SLN (TPSLN), and glycerol behenate SLN (GBSLN), the relatively smaller sized nanoparticles were obtained with 3% sodium tauroglycocholate. The SLN were loaded with an anticancer agent, tamoxifen citrate (TC). The TC-loaded TSSLN shown lower entrapment efficiency (78.78%) compared to the TPSLN (86.75%) and GBSLN (98.64%). Short term stability studies indicated a significant increase in size of nanoparticles when stored at 500C, compared to those stored at 30 degrees C and 4 degrees C. The particle destabilization upon storage in case of all the types of nanoparticles studied was in the order of day light > artificial light > dark. An ultraviolet (UV) spectrophotometric method of estimation of tamoxifen in rat plasma was developed and validated. The TC-loaded TSSLN was administered to the rats intravenously and the pharmacokinetic parameters in the plasma were determined. The t(1/2) and mean residence time of TC-loaded TSSLN in plasma was about 3.5-fold (p < 0.001) and 3-fold (p < 0.001) higher, respectively, than the free tamoxifen, indicating the potential of TC-loaded TSSLN as a long circulating system in blood. Thus the above mentioned solid lipid nanoparticles can be a beneficial system to deliver tamoxifen to cancer tissues through enhanced permeability and retention (EPR) effect. PMID:16749527

Reddy, L Harivardhan; Vivek, K; Bakshi, Nishant; Murthy, R S R

2006-01-01

292

Preparation and Physicochemical Properties of 10-Hydroxycamptothecin (HCPT) Nanoparticles by Supercritical Antisolvent (SAS) Process  

PubMed Central

The goal of the present work was to study the feasibility of 10-hydroxycamptothecin (HCPT) nanoparticle preparation using supercritical antisolvent (SAS) precipitation. The influences of various experimental factors on the mean particle size (MPS) of HCPT nanoparticles were investigated. The optimum micronization conditions are determined as follows: HCPT solution concentration 0.5 mg/mL, the flow rate ratio of CO2 and HCPT solution 19.55, precipitation temperature 35 °C and precipitation pressure 20 MPa. Under the optimum conditions, HCPT nanoparticles with a MPS of 180 ± 20.3 nm were obtained. Moreover, the HCPT nanoparticles obtained were characterized by Scanning electron microscopy, Dynamic light scattering, Fourier-transform infrared spectroscopy, High performance liquid chromatography-mass spectrometry, X-ray diffraction and Differential scanning calorimetry analyses. The physicochemical characterization results showed that the SAS process had not induced degradation of HCPT. Finally, the dissolution rates of HCPT nanoparticles were investigated and the results proved that there is a significant increase in dissolution rate compared to unprocessed HCPT. PMID:21731466

Zhao, Xiuhua; Zu, Yuangang; Jiang, Ru; Wang, Ying; Li, Yong; Li, Qingyong; Zhao, Dongmei; Zu, Baishi; Zhang, Baoyou; Sun, Zhiqiang; Zhang, Xiaonan

2011-01-01

293

?-Lactalbumin nanoparticles prepared by desolvation and cross-linking: structure and stability of the assembled protein.  

PubMed

A key step in the preparation of cross-linked protein nanoparticles involves the desolvation of proteins with an organic solvent, which is thought to act by modulating hydrophobic interactions. However, to date, no study has examined the conformational changes that proteins undergo during the assembly process. In this work, by using several biophysical techniques (CD spectroscopy, DSC, TEM, etc.), we studied spheroidal nanoparticles made from bovine ?-lactalbumin cross-linked with glutaraldehyde in the presence of acetone. Within the nanoparticle, the polypeptide chain acquires a ?-strand-like conformation (completely different from the native protein in secondary and tertiary structure) in which several side chains likely become available for reacting with glutaraldehyde. A multiplicity of cross-linking sites, together with the polymeric nature of glutaraldehyde, may thus explain the low dry-weight fraction of protein that was found in the nanoparticles. Although covalent bonds undoubtedly constitute the main source for nanoparticle stability, noncovalent interactions also appear to play a role in this regard. PMID:25105879

Arroyo-Maya, Izlia J; Hernández-Sánchez, Humberto; Jiménez-Cruz, Esmeralda; Camarillo-Cadena, Menandro; Hernández-Arana, Andrés

2014-01-01

294

Stability, size and optical properties of silver nanoparticles prepared by laser ablation in different carrier media  

NASA Astrophysics Data System (ADS)

We studied the effects of the surrounding liquid environment on the size and optical properties of silver nanoparticles prepared by laser ablation by a pulsed Nd:YAG laser operated at 1064 nm. The silver targets used were kept in acetone, water and ethanol. TEM observations and optical extinction were employed for characterization of particle size, shape and optical properties, respectively. Nano silver in acetone showed a narrow size distribution with a mean size of 5 nm and the colloidal solution was stable. In deionised water a rather narrow size distribution with a mean size of 13 nm was observed and nanoparticles were precipitated slowly after about two weeks. In ethanol, a broadening in size distribution and optical extinction spectra was observed. Silver nanoparticles in ethanol with a mean size of 22 nm were completely precipitated after 48 h. In acetone, deionised water and ethanol, the wavelengths of maximum optical extinction are 399, 405 and 411 nm respectively, which is attributed to increasing the size of the nanoparticles. Growth, aggregation and precipitation mechanisms were related to the dipole moment of the surrounding molecules in order to clarify the difference in size, optical properties and stability of the nanoparticles.

Tilaki, R. M.; Iraji Zad, A.; Mahdavi, S. M.

2006-07-01

295

Chitosan-lignosulfonates sono-chemically prepared nanoparticles: characterisation and potential applications.  

PubMed

Due to their recognised properties of biocompatibility, biodegradability and sustainability, chitosan nanocarriers have been successfully used as new delivery systems. In this work, nanoparticles combining chitosan and lignosulfonates were developed for the first time for cosmetic and biomedical applications. The ability of lignosulfonates to act as a counter polyion for stabilisation of chitosan particles, generated using high intensity ultrasound, was investigated. Several conditions for particles preparation were tested and optimised and the resulting nanoparticles were comprehensively characterised by measuring particle size, zeta potential and polydispersity index. The pH of chitosan solution, sonication time and the presence of an adequate surfactant, poloxamer 407, were determinant factors on the development of smaller particles with low polydispersity index (an average particle size of 230 nm was obtained at pH 5 after 8 min of sonication). The beneficial effects of lignosulfonates complex on chitosan nanoparticles were further characterised. Greater stability to lysozyme degradation, biocompatibility with human cells and antimicrobial activity was found upon lignosulfonates incorporation into chitosan nanoparticles. Furthermore, these particles were able to incorporate a hydrophilic model protein - RNase A. A burst release was observed when nanoparticles were loaded with low amount of protein while with high protein content, a sustained release was found, suggesting that the protein cargo maybe loaded both at the surface as in the bulk of the particle, depending on the concentration of drug incorporated. PMID:23178385

Kim, Suyeon; Fernandes, Margarida M; Matamá, Teresa; Loureiro, Ana; Gomes, Andreia C; Cavaco-Paulo, Artur

2013-03-01

296

Preparation, characterization, and in vivo evaluation of tanshinone IIA solid dispersions with silica nanoparticles  

PubMed Central

We prepared solid dispersions (SDs) of tanshinone IIA (TSIIA) with silica nanoparticles, which function as dispersing carriers, using a spray-drying method and evaluated their in vitro dissolution and in vivo performance. The extent of TSIIA dissolution in the silica nanoparticles/TSIIA system (weight ratio, 5:1) was approximately 92% higher than that of the pure drug after 60 minutes. However, increasing the content of silica nanoparticles from 5:1 to 7:1 in this system did not significantly increase the rate or extent of TSIIA dissolution. The physicochemical properties of SDs were investigated using scanning electron microscopy, differential scanning calorimetry, X-ray powder diffraction, and Fourier transforms infrared spectroscopy. Studying the stability of the SDs of TSIIA revealed that the drug content of the formulation and dissolution behavior was unchanged under the applied storage conditions. In vivo tests showed that SDs of the silica nanoparticles/TSIIA had a significantly larger area under the concentration-time curve, which was 1.27 times more than that of TSIIA (P < 0.01). Additionally, the values of maximum plasma concentration and the time to reach maximum plasma concentration of the SDs were higher than those of TSIIA and the physical mixing system. Based on these results, we conclude that the silica nanoparticle based SDs achieved complete dissolution, increased absorption rate, maintained drug stability, and showed improved oral bioavailability compared to TSIIA alone. PMID:23836971

Jiang, Yan-rong; Zhang, Zhen-hai; Liu, Qi-yuan; Hu, Shao-ying; Chen, Xiao-yun; Jia, Xiao-bin

2013-01-01

297

Preparation and characterization of oligochitosan-tragacanth nanoparticles as a novel gene carrier.  

PubMed

The nanoparticles of oligochitosan-water soluble tragacanth (OCH-WST) as novel gene carriers have been prepared and their transfection efficiency has been investigated on Hela and HepG2 cell lines. Different OCH:WST weight ratios were prepared to obtain particles with low size distribution and high surface charge, and also in range of below 200 nm. Nanoparticles with 132.5 ± 6.77 nm size, polydispersity index 1.92 ± 0.061, surface charge 30.45 ± 1.84 and spherical morphology, have been chosen as gene carrier. Nanoparticle-DNA complexes (nanoplexes) showed better transfection efficiency in both Hela and HepG2 cells than chitosan polyplexes, with 1.26 × 10(6) versus 9.05 × 10(5) and 7.76 × 10(5) versus 2.16 × 10(5), respectively. Higher transfection efficiency of nanoplexes could be attributed to their weaker complexation. Decreasing of transfection in presence of galactose in HepG2 cells, indicated receptor mediated endocytosis of nanoplexes. These properties all together, make OCH-WST nanoparticles as potential gene carrier for active gene delivery into cells containing sugar receptors. PMID:23911446

Fattahi, Ali; Sadrjavadi, Komail; Golozar, Mohammad Ali; Varshosaz, Jaleh; Fathi, Mohammad-Hossein; Mirmohammad-Sadeghi, Hamid

2013-09-12

298

Preparation and anti-bacterial properties of a temperature-sensitive gel containing silver nanoparticles.  

PubMed

The purpose of this study was to prepare a temperature-sensitive gel containing silver nanoparticles and to investigate its anti-bacterial properties in vitro. The aqueous gel was prepared using Pluronic F127 (18-22%) and Pluronic F68 (3-9%) in a cold method to obtain a proper gelation temperature at 37 degrees C. Viscoelastic properties of the system were measured by rheological measurements and the physicochemical properties were evaluated by MJ-22 Dial-reflex metaloscope and Zetasizer Nano ZS90. The in vitro antimicrobial activity was evaluated by a disk diffusion test, minimum inhibitory concentration, and minimum bactericidal concentration. A temperature-sensitive gel containing silver nanoparticles with 20 wt% F127 and 6 wt% F68 had suitable fluidity at 25 degrees C and was semi-solid at 37 degrees C. Silver nanoparticle size averaged 78.0 nm. The gel optimized formulation achieved a suitable viscosity. The MIC and MBC of the gel ranged from 1.0 to 2.0 mg/L against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The activity of the gel against these three species was significantly enhanced (p<0.05) compared to 400 mg/L Asimi standard. This optimized silver nanoparticle dosage form demonstrated a high potential for further development for the clinical treatment of bacterial vaginosis. PMID:21612154

Chen, Meiwan; Pan, Xin; Wu, Hongmei; Han, Ke; Xie, Xiaobao; Wedge, D E; Repka, M A; Wu, Chuanbin

2011-04-01

299

Film electrode prepared from oppositely charged silicate submicroparticles and carbon nanoparticles for selective dopamine sensing.  

PubMed

Film electrodes prepared from oppositely charged silicate submicroparticles and carbon nanoparticles was applied for selective dopamine sensing. Mesoporous silicate submicroparticles with tetraalkylammonium functionalities were prepared by sol-gel method. They were immobilised on an indium tin oxide film surface together with phenylsulphonated carbon nanoparticles by layer-by-layer method: alternative immersion into their suspensions. As it is shown by scanning electron microscopy the obtained film is composed of silicate submicroparticles covered by carbon nanoparticles. The nanoparticulate film is stable and its electroactive surface is significantly larger than substrate. Accumulation of redox active cations indicates that only fraction charged functionalities of carbon nanoparticles are employed in film formation. The obtained electrode exhibits catalytic properties towards dopamine oxidation and its interferences as ascorbic acid, uric acid and acetaminophen. This allows for selective determination of tenth micromolar concentration of dopamine in the presence of these interferences at milimolar level. The detection limit and linear range were determined to 0.1 × 10?? mol dm?³ and 0.3-18 × 10?? mol dm?³ respectively. PMID:21641787

Celebanska, Anna; Tomaszewska, Dorota; Lesniewski, Adam; Opallo, Marcin

2011-07-15

300

Controllable preparation and properties of composite materials based on ceria nanoparticles and carbon nanotubes  

SciTech Connect

We report a method to prepare composites based on carbon nanotubes (CNTs) and CeO{sub 2} nanoparticles (NPs). The CeO{sub 2} NPs were attached to CNTs by hydrothermal treatment of Ce(OH){sub 4}/CNT mixture in NaOH solution at 180 deg. C. It was found that larger CeO{sub 2} NPs were formed in the presence of CNTs. Grain size of CeO{sub 2} NPs in the composites can be reduced when NaNO{sub 3} was added in the hydrothermal process. Electrochemical characterizations have shown that the composites possess a specific capacity between those of CNTs and CNTs mechanically mixed with CeO{sub 2}. These CeO{sub 2}/CNT composites could serve as promising anode materials for Li-ion batteries. - Graphical abstract: Composites based on carbon nanotubes (CNTs) and CeO{sub 2} nanoparticles were prepared with a mild hydrothermal treatment. Larger CeO{sub 2} nanoparticles were formed in the presence of CNTs. Grain size of CeO{sub 2} nanoparticles in composites could be reduced when NaNO{sub 3} was added. The size modulation mechanism was discussed. This CeO{sub 2}/CNTs composites could serve as promising anode materials for Li-ion batteries.

Li Changqing; Sun Nijuan; Ni Jiangfeng; Wang Jinyong; Chu Haibin; Zhou Henghui; Li Meixian [Beijing National Laboratory for Molecular Sciences, National Laboratory of Rare Earth Material Chemistry and Application, Key Laboratory for the Physics and Chemistry of Nanodevices, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Li Yan [Beijing National Laboratory for Molecular Sciences, National Laboratory of Rare Earth Material Chemistry and Application, Key Laboratory for the Physics and Chemistry of Nanodevices, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)], E-mail: yanli@pku.edu.cn

2008-10-15

301

Chirality control for in situ preparation of gold nanoparticle superstructures directed by a coordinatable organogelator.  

PubMed

Imposing chirality into nanoscale superstructures is a major step forward toward systematic understanding and utilization of nanomaterials. In an attempt to achieve tunable chirality during in situ preparation of hybrid nanomaterials, we here report a novel unimolecular strategy of employing a coordinatable organogelator for the realization of chirality control in the formation of gold nanoparticle superstructures. The work takes advantage of thermally reversible sol-gel transition of the chiral dispersion as template, which causes different micelle properties that can influence the coordination ability between the organogelator and Au(III) ions. Followed by a reduction reaction, gold nanoparticle superstructures with P-helicity were prepared from the sol form of the template through a coordination-induced chiral inversion, whereas those with M-helicity were obtained from the gel form with chiral holding. Such superstructures are solvent-stable and the chirality difference between them could be observed in many solvent environments. PMID:23705828

Zhu, Liangliang; Li, Xin; Wu, Shaojue; Nguyen, Kim Truc; Yan, Hong; Ågren, Hans; Zhao, Yanli

2013-06-19

302

Preparation of chain copper oxide nanoparticles by microwave  

Microsoft Academic Search

Cu(OH)2 nano-fibers were prepared by chemical precipitation with CuSO4·5H2O and NaOH as raw materials. The Cu(OH)2 nano-fibers have a diameter of 10–30 nm and a length of 1–6 ?m. The reaction conditions were as follows: the concentration of CuSO4 solution was 0.1 mol·LT?1, NaOH solution 4 mol·L?1, the dropping rate of the NaOH solution 50 mL·min?1, the reaction temperature 20°C,

Zaiyuan LI; Yan LIU; Panwei GONG; Yuchun ZHAI

2007-01-01

303

The preparation and characterization of La doped TiO 2 nanoparticles and their photocatalytic activity  

Microsoft Academic Search

In this paper, pure and La doped TiO2 nanoparticles with different La content were prepared by a sol–gel process using Ti (OC4H9)4 as raw material, and also were characterized by XRD, TG-DTA, TEM, XPS, DRS and Photoluminescence (PL) spectra. We mainly investigated the effects of calcining temperature and La content on the properties and the photocatalytic activity for degrading phenol

Jing Liqiang; Sun Xiaojun; Xin Baifu; Wang Baiqi; Cai Weimin; Fu Honggang

2004-01-01

304

Preparation and optical properties of silica gel–glass doped with ZnSe nanoparticles  

Microsoft Academic Search

The silica gel–glasses doped with zinc selenide (ZnSe) nanoparticles were prepared by the sol–gel technique which was followed by a reductive thermal treatment. The samples were characterized by transmission electron microscopy (TEM), X-ray diffraction pattern (XRD), optical absorption and photoluminescence spectra. The blue shift of the absorption edge can be changed and used to evaluate the average size of the

Minqiang Wang; Yaohui Xue; Zhonghai Lin; Xiao Huo; Jianping Li; Xi Yao

2008-01-01

305

Preparation and characterization of gelatin mediated silver nanoparticles by laser ablation  

Microsoft Academic Search

We successfully prepared colloidal silver nanoparticles (Ag-NPs) using a nanosecond pulsed Nd:YAG laser, ?=532nm, with laser fluence of approximately about 0.6J\\/pulse, in an aqueous gelatin solution. The size and optical absorption properties of samples were studied as a function of the laser repetition rates. The results from the UV–vis spectroscopy demonstrated that the mean diameter of Ag-NPs increase with the

Majid Darroudi; Mansor B. Ahmad; Reza Zamiri; Abdul Halim Abdullah; Nor Azowa Ibrahim; Kamyar Shameli; M. Shahril Husin

306

Time-dependent preparation of gelatin-stabilized silver nanoparticles by pulsed Nd:YAG laser  

Microsoft Academic Search

Colloidal silver nanoparticles (Ag-NPs) were successfully prepared using a nanosecond pulsed Nd:YAG laser, ? = 1064 nm, with laser fluence of approximately about 360 mJ\\/pulse, in an aqueous gelatin solution. In this work, gelatin was used as a stabilizer, and the size and optical absorption properties of samples were studied as a function of the laser ablation times. The results from the UV–vis spectroscopy

Majid Darroudi; M. B. Ahmad; Reza Zamiri; A. H. Abdullah; N. A. Ibrahim; A. R. Sadrolhosseini

2011-01-01

307

Preparation and ultrafast optical characterization of metal and semiconductor colloidal nano-particles  

Microsoft Academic Search

The ultrafast dynamics of photoinduced electrons in several metal and semiconductor colloidal nanoparticle systems are characterized\\u000a using femtosecond laser spectroscopy. Various preparation methods are used and, in several cases, modified for making particles\\u000a with long-term stability and narrow and controllable size distributions. The particle size and size distribution are determined\\u000a using transmission electron microscopy and electronic absorption spectroscopy. For aqueous

B. A. Smith; D. M. Waters; A. E. Faulhaber; M. A. Kreger; T. W. Roberti; J. Z. Zhang

1997-01-01

308

Preparation and antibacterial activities of undoped and palladium doped titania nanoparticles  

Microsoft Academic Search

Undoped and palladium doped titania nanoparticles have been prepared by sol–gel method using isopropyl alcohol as solvent.\\u000a The products have been characterized through XRD, FESEM, TEM, HRTEM, FTIR, specific surface area analysis and ICPOES technologies.\\u000a The antibacterial activities of the products against Escherichia coli (E. Coli) have been investigated by microcalorimetric method and antibacterial circle method, respectively. The process of

Zhihong Jing; Chuancai Wang; Guangli Wang; Wenjuan Li; Dongmei Lu

2010-01-01

309

Preparation of silver nanoparticles with antimicrobial activities and the researches of their biocompatibilities  

Microsoft Academic Search

Silver nanoparticles were prepared by chemical reduction method using chitosan as stabilizer and ascorbic acid as reducing\\u000a agent in this work. The silver\\/chitosan nanocomposites were characterized in terms of their particle sizes and morphology\\u000a by using UV spectrophotometer, nano-grainsize analyzer, and transmission electron microscopy. Antibacterial activities of\\u000a these nanocomposites were carried out for Staphylococcus aureus and Escherichia coli. The silver

X. L. Cao; C. Cheng; Y. L. Ma; C. S. Zhao

2010-01-01

310

Preparation and Physicochemical Characterization of Aqueous Dispersions of Coenzyme Q 10 Nanoparticles  

Microsoft Academic Search

The present study describes a novel pharmaceutical formulation of coenzyme Q10, viz. submicron-sized dispersions of the substance prepared by emulsification of molten coenzyme Q10 in an aqueous phase. Photon correlation spectroscopy reveals mean diameters of 60 to 300 nm depending on process parameters. Coenzyme Q10 nanoparticles remain stable on storage for more than 30 months. Lipophilic drugs can be incorporated

Britta Siekmann; Kirsten Westesen

1995-01-01

311

Preparation and characterization of carbon paste micro-electrode based on carbon nano-particles  

Microsoft Academic Search

The present paper demonstrates the preparation and characterization of micro-electrodes based on carbon paste which is composed of carbon nano-particles with an average diameter of 30nm and binding oil. The carbon paste electrode material is encased in pulled glass capillaries ranging in diameter from several tens down to less than ten micro-meters (r=4.5?m). Manipulation of the carbon paste micro-electrode (CPME)

Samo B. Ho?evar; Božidar Ogorevc

2007-01-01

312

Preparation of cells for assessing ultrastructural localization of nanoparticles with transmission electron microscopy  

Microsoft Academic Search

We describe the use of transmission electron microscopy (TEM) for cellular ultrastructural examination of nanoparticle (NP)-exposed biomaterials. Preparation and imaging of electron-transparent thin cell sections with TEM provides excellent spatial resolution (?1 nm), which is required to track these elusive materials. This protocol provides a step-by-step method for the mass-basis dosing of cultured cells with NPs, and the process of

Amanda M Schrand; John J Schlager; Liming Dai; Saber M Hussain

2010-01-01

313

Preparation, Characterization and Catalytic Activity of Palladium Nanoparticles Encapsulated in SBA15  

Microsoft Academic Search

A simple adsorption method was studied for the preparation of SBA-15-encapsulated palladium nanoparticles. This method employed\\u000a the SBA-15 with organic template removed by ethanol extraction for the adsorption of cationic Pd precursors in alkaline solution\\u000a followed by calcination and H2 reduction. The pH of the solution was found to be a critical factor in determining the palladium content and the

Changli Li; Qinghong Zhang; Ye Wang; Huilin Wan

2008-01-01

314

Paclitaxel-loaded PLGA nanoparticles: preparation, physicochemical characterization and in vitro anti-tumoral activity  

Microsoft Academic Search

The main objective of this study was to develop a polymeric drug delivery system for paclitaxel, intended to be intravenously administered, capable of improving the therapeutic index of the drug and devoid of the adverse effects of Cremophor® EL. To achieve this goal paclitaxel (Ptx)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (Ptx-PLGA-Nps) were prepared by the interfacial deposition method. The influence of

Cristina Fonseca; Sérgio Simões; Rogério Gaspar

2002-01-01

315

NOVEL PREPARATION AND MAGNETO CHEMICAL CHARACTERIZATION OF NANO-PARTICLE MIXED ALCOHOL CATALYSTS  

SciTech Connect

The preparation of Cu, Co, Fe, Cu/Co, Cu/Fe and Co/Fe nano-particle metal loaded mesoporous 1 mm spherical granular {gamma}-Al{sub 2}O{sub 3} catalysts, by combined sol-gel/oil-drop methods followed by calcination and hydrogenation steps, is accomplished. Parameters for calcination process were optimized using DTA. The properties of metal loaded {gamma}-Al{sub 2}O{sub 3} granules were compared for the preparations starting with two precursors: aluminum tri-sec-butoxide (ALTSB) and aluminum tri-iso-propoxide (ALTIP). Three sol-gel/oil-drop catalyst preparation methods; (1) Metal nitrate solutions co-entrapped-sol-gel (2) nano-particle metal oxide co-entrapped-sol-gel, and (3) Metal impregnation on preformed alumina granules, were used. Structure and composition of metal-loaded-granules were investigated using XRD, SEM, EDX, and surface area measurements (BET method). The nano-particle nature of catalysts was confirmed using SEM and X-ray diffraction. The reduction efficiency of hydrogenation of catalysts was examined by magnetic studies using a vibrating sample magnetometer (VSM). Catalysts could be effectively calcined at 450 C and the surface area values obtained were between 200-350 m{sup 2}/g, indicating the mesoporous nature of catalyst support. Parameters affecting the metal loading process were also studied, and the optimum conditions were identified and reported for reproducible synthesis of the metal loaded {gamma}-alumina granular particles. The catalyst activities of Fe, Co, and Co/Fe on alumina for the conversion of CO/H{sub 2} and CO{sub 2}/H{sub 2} mixtures were investigated using Gas chromatography (GC) with N{sub 2} as a standard carrier gas. Both, slurry-phase-batch and gas-phase-continuous-flow, reactors were used. Magnetization studies on reduced, CO/H{sub 2} post-reaction catalyst in both gas and slurry phase were performed using vibrating sample magnetometer (VSM). Magnetic studies of post-reaction Co and Fe nano-catalysts showed that the formation of carbides is higher for iron compared to cobalt. In the Fe/Co mixed catalyst, it is observed that the presence of iron enhances the cobalt oxide reduction. Catalyst with mixed metal Fe/Co compositions at 12% nitrate solutions (prepared by sol-gel/oil-drop) showed the best conversion rates for the syngas (CO+H{sub 2}). Nano-particle catalysts on sol-gel prepared mesoporous {gamma}-alumina (particularly the nano-particle metal oxide co-entrapped-sol-gel) showed higher conversion rates compared to conventional catalysts prepared by coprecipitation methods.

Seetala V. Naidu; Upali Siriwardane; Akundi N. Murty

2004-02-23

316

Synthesis of chromium-nickel nanoparticles prepared by a microemulsion method and mechanical milling.  

PubMed

A chemical and a physical method have been applied for the preparation of chromium-nickel alloy nanoparticles. These particles were designed to be used for controlled magnetic hyperthermia applications. Microemulsions with Ni2+ and Cr3+ and/or NaBH4 as precursors were prepared using the isooctane/CTAB, n-butanol/H2O system. The samples of CrxNi1-x nanoparticles with the desired composition were obtained after the reduction of their salts with NaBH4 and afterwards heat treated in a TGA in a N2 atmosphere at various temperatures. The CrxNi1-x materials were also prepared by mechanical milling. Utilizing a ball-to-powder mass ratio of 20 : 1 and selecting the proper alloy compositions we were able to obtain nanocrystalline CrxNi1-x particles. Thermal demagnetization in the vicinity of the Curie temperature of the nanoparticles was studied using a modified TGA-SDTA method. The alloy's phase composition, size and morphology were determined with XRD measurements and TEM analyses. PMID:24362977

Ban, Irena; Stergar, Janja; Drofenik, Miha; Ferk, Gregor; Makovec, Darko

2013-01-01

317

Effect of Aluminium Doping on Structural and Optical Properties of ZnO Nanoparticles Prepared by Mechanochemical Synthesis  

Microsoft Academic Search

Optical properties of metal ion doped zinc oxide (ZnO) nanoparticles synthesized by various methods were reported to display different properties. Nevertheless, there are limited reports on metal ion doped ZnO prepared by mechanochemical synthesis. This paper reports the effect of aluminium doping on structural and optical properties of ZnO (Zn1-xAlxO,x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) nanoparticles prepared by

Nurul Syahidah Sabri; A. K. Yahya; Mahesh Kumar Talari

2011-01-01

318

Effect of Aluminium Doping on Structural and Optical Properties of ZnO Nanoparticles Prepared by Mechanochemical Synthesis  

Microsoft Academic Search

Optical properties of metal ion doped zinc oxide (ZnO) nanoparticles synthesized by various methods were reported to display different properties. Nevertheless, there are limited reports on metal ion doped ZnO prepared by mechanochemical synthesis. This paper reports the effect of aluminium doping on structural and optical properties of ZnO (Zn1-xAlxO, x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) nanoparticles prepared

Nurul Syahidah Sabri; A. K. Yahya; Mahesh Kumar Talari

2011-01-01

319

Chemically reduced and laser-ablated gold nanoparticles immobilized to silanized glass plates: Preparation, characterization and SERS spectral testing  

Microsoft Academic Search

SERS-active surfaces based on gold colloidal nanoparticles attached to silanized glass plates were prepared and characterized by surface plasmon extinction (SPE) and atomic force microscopy (AFM). Aminopropyltrimethoxysilane (APTMS) was found to be more efficient in the silanization process than mercaptopropyltrimethoxysilane (MPTMS). Gold colloidal nanoparticles prepared by three different procedures, i.e. laser-ablation and chemical reduction of HAuCl4 by sodium borohydride or

Natália Hajduková; Marek Procházka; Josef Št?pánek; Milena Špírková

2007-01-01

320

Electrically conductive properties of Ag/Si composite nanoparticle assembled films prepared with a plasma–gas-condensation cluster source  

NASA Astrophysics Data System (ADS)

Ag1?x/Six composite nanoparticle assembled films were prepared using a plasma–gas-condensation cluster beam deposition apparatus. The electrical conductivity ? and Hall coefficient |RH| of Ag1?x/Six nanoparticle assembled films obey a power law of the volume fraction of Ag pAg. The marked change at around pAg = pc indicates that the percolation of Ag nanoparticles takes place at the threshold value pc. Moreover, we found that the |RH| at T = 5 K of the Ag1?x/Six nanoparticle assembled film with the closest pAg to pc is 20 times higher than that of the bulk Ag.

Kurokawa, Yuichiro; Hihara, Takehiko

2014-11-01

321

Zirconium arsenate-modified magnetic nanoparticles: preparation, characterization and application to the enrichment of phosphopeptides.  

PubMed

Phosphorylation, one of the most important post-translational modifications of protein, plays a crucial role in a large number of biological processes. Large-scale identification of protein phosphorylation by mass spectrometry is still a challenging task because of the low abundance of phosphopeptides and sub-stoichiometry of phosphorylation. In this work, a novel strategy based on the specific affinity of zirconium arsenate to the phosphate group has been developed for the effective enrichment of phosphopeptides. Zirconium arsenate-modified magnetic nanoparticles (ZrAs-Fe(3)O(4)@SiO(2)) were prepared by covalent immobilization of zirconium arsenate on Fe(3)O(4)@SiO(2) magnetic nanoparticles under mild conditions, and characterized by transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). The prepared ZrAs-Fe(3)O(4)@SiO(2) was applied for the selective enrichment of phosphopeptides from the digestion mixture of phosphoproteins and bovine serum albumin (BSA). Our results demonstrated that the ZrAs-Fe(3)O(4)@SiO(2) magnetic nanoparticles possess higher selectivity for phosphopeptides and better capture capability towards multiply-phosphorylated peptides than commercial zirconium dioxide (ZrO(2)), which has been widely employed for the enrichment of phosphopeptides. In addition, endogenous phosphopeptides from human serum can be effectively captured by ZrAs-Fe(3)O(4)@SiO(2) magnetic nanoparticles. It is the first report, to the best of our knowledge, in which the zirconium arsenate-modified magnetic nanoparticles were successfully applied to the enrichment of phosphopeptides, which offers the potential application of this new material in phosphoproteomics study. PMID:22182930

Li, Xiao-Shui; Xu, Li-Dan; Zhu, Gang-Tian; Yuan, Bi-Feng; Feng, Yu-Qi

2012-02-21

322

High frequency AC response, DC resistivity and magnetic studies of holmium substituted Ni-ferrite: A novel electromagnetic material  

NASA Astrophysics Data System (ADS)

Nanoparticles of holmium substituted nickel ferrites (NiHoxFe2-xO4) with x ranging from 0.0 to 0.15 have been prepared by the sol-gel auto-combustion method. Structural and morphology studies have been performed by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). XRD patterns revealed the formation of pure spinel phase ferrites without any impurity phase. Lattice parameter increases along with a decrease in crystallite size with increasing the concentration of Ho3+ in the parent nickel ferrite due to large ionic radius of Ho3+ (0.901 Å) as compared to Fe3+ (0.67 Å). SEM shows the spherical, uniformly distributed homogenous nanoparticles grown by controlled reaction parameters of the sol-gel method. Complex permittivity (?*) and complex electric modulus (M*) have been studied for the present nanoferrites in the frequency ranges of 1 MHz-1 GHz. Frequency dependent dielectric parameters (relative permittivity (?'), dielectric loss (??), dielectric loss tangent (tan ?)) decreases due to holmium substitution in nickel ferrites, showing the electrical conduction is decreasing in the nickel holmium ferrites with increase in the concentration of holmium. Complex modulus plots shows the poorly resolved semi circles and relaxation of nanoferrite is studied in the high frequency region. Also the relaxation time increases due to increase in x (0.0-0.15). DC electrical resistivity increases (107 ?-cm-1010 ?-cm) due to holmium ions substitution in nickel ferrites. Magnetic behavior was also characterized using a Vibrating Sample Magnetometer (VSM) under an applied magnetic field of 10 kOe and shows that magnetization decreases with increase in composition of holmium in nickel ferrites. High frequency behavior, low losses and very high DC electrical resistivity made the material a novel one for electromagnetic devices.

Pervaiz, Erum; Gul, I. H.

2014-01-01

323

Structural and magnetic properties of Mn nanoparticles prepared by arc-discharge  

SciTech Connect

Mn nanoparticles are prepared by arc discharge technique. MnO, {alpha}-Mn, {beta}-Mn, and {gamma}-Mn are detected by X-ray diffraction, while the presence of Mn{sub 3}O{sub 4} and MnO{sub 2} is revealed by X-ray photoelectron spectroscopy. Transmission electron microscopy observations show that most of the Mn nanoparticles have irregular shapes, rough surfaces and a shell/core structure, with sizes ranging from several nanometers to 80 nm. The magnetic properties of the Mn nanoparticles are investigated between 2 and 350 K at magnetic fields up to 5 T. A magnetic transition occurring near 43 K is attributed to the formation of the ferrimagnetic Mn{sub 3}O{sub 4}. The coercivity of the Mn nanoparticles, arising mainly from Mn{sub 3}O{sub 4}, decreases linearly with increasing temperature below 40 K. Below the blocking temperature T{sub B} {approx} 34 K, the hysteresis loops exhibit large coercivity (up to 500 kA/m), owing to finite size effects, and irreversibility in the loops is found up to 4 T, and magnetization is not saturated up to 5 T. The relationship between structure and the magnetic properties are discussed.

Si, P.Z. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China) and Van der Waals-Zeeman Institute, University of Amsterdam, ValckenierstrAt 65, NL-1018 XE Amsterdam (Netherlands)]. E-mail: psi@science.uva.nl; Brueck, E. [Van der Waals-Zeeman Institute, University of Amsterdam, ValckenierstrAt 65, NL-1018 XE Amsterdam (Netherlands); Zhang, Z.D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China); Tegus, O. [Van der Waals-Zeeman Institute, University of Amsterdam, ValckenierstrAt 65, NL-1018 XE Amsterdam (Netherlands); Zhang, W.S. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China); Buschow, K.H.J. [Van der Waals-Zeeman Institute, University of Amsterdam, ValckenierstrAt 65, NL-1018 XE Amsterdam (Netherlands); KlAsse, J.C.P. [Van der Waals-Zeeman Institute, University of Amsterdam, ValckenierstrAt 65, NL-1018 XE Amsterdam (Netherlands)

2005-01-04

324

Preparation and magnetic resonance imaging effect of polyvinylpyrrolidone-coated iron oxide nanoparticles.  

PubMed

Polyvinylpyrrolidone (PVP)-coated iron oxide nanoparticles were prepared by the thermal decomposition of Fe(CO)(5) (iron pentacarbonyl) in one step. X-ray diffraction (XRD), transmission electron microscopy (TEM), electrophoretic light scattering (ELS), infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) together with the variation of the molar ratio of PVP/Fe(CO)(5), solvent, and molecular weight of PVP, were used to characterize the PVP-coated iron oxide nanoparticles. Fifty to hundred nanometer-sized iron oxide nanoclusters with a spherical shape were formed in dimethylformamide (DMF), used as a solvent, and exhibited an enhanced stability in the aqueous media. Their magnetic properties were investigated by superconducting quantum interface device (SQUID). The in vitro cytotoxicity test revealed that the PVP-coated iron oxide nanoparticles exhibited excellent biocompatibility by MTT assay. Magnetic resonance imaging (MRI) effect was observed with the administration of PVP-coated iron oxide nanoparticles through the marginal vein of rabbit, resulting in improved detection of the liver lesions. PMID:16767710

Lee, Ha Young; Lim, Nak Hyun; Seo, Jin A; Yuk, Soon Hong; Kwak, Byung Kook; Khang, Gilson; Lee, Hai Bang; Cho, Sun Hang

2006-10-01

325

Preparation of poly(?-caprolactone)-based polyurethane nanofibers containing silver nanoparticles  

NASA Astrophysics Data System (ADS)

In this study, poly(?-caprolactone)-based polyurethane (PCL-PU) nanofibers containing Ag nanoparticles for use in antimicrobial nanofilter applications were prepared by electrospinning 8 wt% PCL-PU solutions containing different amounts of AgNO 3 in a mixed solvent consisting of DMF/THF (7/3 w/w). The average diameter of the pure PCL-PU nanofibers was 560 nm and decreased with increasing concentration of AgNO 3. The PCL-PU nanofiber mats electrospun with AgNO 3 exhibited higher tensile strength, tensile modulus, and lower elongation than the pure PCL-PU nanofiber mats. Small Ag nanoparticles were produced by the reduction of Ag + ions in the PCL-PU solutions. The average size and number of the Ag nanoparticles in the PCL-PU nanofibers were considerably increased after being annealed at 100 °C for 24 h. They were all sphere-shaped and evenly distributed in the PCL-PU nanofibers, indicating that the PCL-PU chains stabilized the Ag nanoparticles well.

Jeon, Hyun Jeong; Kim, Jin Sook; Kim, Tae Gon; Kim, Jung Hyun; Yu, Woong-Ryeol; Youk, Ji Ho

2008-07-01

326

Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties  

SciTech Connect

In this paper, a simple strategy is developed for rational fabrication of a class of jingle-bell-shaped hollow structured nanomaterials marked as Ag(MFe{sub 2}O{sub 4}) (M=Ni, Co, Mg, Zn), consisting of ferrite hollow shells and metal nanoparticle cores, using highly uniform colloidal Ag(C) microspheres as template. The final composites were obtained by direct adsorption of metal cations Fe{sup 3+} and M{sup 2+} on the surface of the Ag(C) spheres followed by calcination process to remove the middle carbon shell and transform the metal ions into pure phase ferrites. The as-prepared composites were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy and SQUID magnetometer. The results showed that the composites possess the magnetic property of the ferrite shell and the optical together with antibacterial property of the Ag core. - Graphical abstract: MFe{sub 2}O{sub 4} (M=Ni, Co, Mg, Zn) hollow spheres with a noble metal nanoparticle core were successfully prepared by using colloidal metal(C) core-shell spheres as templates with no need of surface modification. The shell thickness and magnetic properties of the ferrite hollow spheres could be controlled by varying the synthetic parameters.

Li Siheng [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China); Wang Enbo [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)], E-mail: Wangeb889@nenu.edu.cn; Tian Chungui; Mao Baodong; Kang Zhenhui; Li Qiuyu; Sun Guoying [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)

2008-07-15

327

Functionalized lipid nanoparticles-cellophane hybrid films for molecular delivery: preparation, physicochemical characterization, and stability.  

PubMed

Lipid nanoparticles functionalized with the sunscreen 2,4-dihydroxybenzophenone (FLNPs) have been prepared by the ultrasound method and embedded in highly hydrophilic cellophane supports (regenerated cellulose, RC), creating biocompatible hybrid films (RC-FLNPs samples). The morphology of the FLNPs was studied with transmission microscopy, whereas the surface and interior chemical composition was analyzed by micro-Raman spectroscopy. RC-FLNPs hybrid films were prepared from the immersion of two cellophane supports with different thicknesses and water uptake properties (RC-3 and RC-6) in an aqueous dispersion of FLNPs. The structure of this hybrid material was visualized with bright-field microscopy, which clearly showed the inclusion of the FLNPs in the cellophane matrix. The stability of the RC-FLNPs films with respect to both aqueous environments and time was demonstrated by NaCl diffusion measurements. The reduction in the diffusion coefficient through the nanoparticle-modified films compared with the original supports confirms the presence of nanoparticles for concentration gradients of up to 0.4 M (osmotic pressure around 10 bar), indicating the stability of the hybrid hydrophilic material, even in aqueous environments and under matter flow conditions for a period of 21 days. PMID:21713774

Vázquez, M Isabel; Peláez, Laura; Benavente, Juana; López-Romero, J Manuel; Rico, Rodrigo; Hierrezuelo, Jesus; Guillén, Elena; López-Ramírez, M Rosa

2011-11-01

328

Water-Soluble Spinel Ferrites by a Modified Polyol Process as Contrast Agents in MRI  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have recently been very attractive for biomedical applications. In this study, we have synthesized ferrite nanoparticles for application as contrast agents in MRI experiments. Fe3O4 and MnFe2O4 spinel ferrites with a mean size of 11-12 nm, were prepared by a modified polyol route in commercially available polyethylene glycol with molecular weight 600 (PEG-600). The reaction takes place in the presence of water soluble and non-toxic tri-block copolymer known as Pluronic® F-127 (PEO100-PPO65-PEO100). The nanoparticles have saturation magnetization values of 52 and 68 emu/g for MnFe2O4 and Fe3O4, respectively. Both the Fe3O4, and MnFe2O4 nanoparticles make stable solutions in water known as ferrofluids. Preliminary data demonstrated the capability of these nanoparticles to induce imaging contrast in T2 weighted MRI experiments, making these materials suitable for biomedical applications such as medical MRI.

Basina, Georgia; Tzitzios, Vasilis; Niarchos, Dimitris; Li, Wanfeng; Khurshid, Hafsa; Mao, Hui; Hadjipanayis, Costas; Hadjipanayis, George

2010-12-01

329

Water-Soluble Spinel Ferrites by a Modified Polyol Process as Contrast Agents in MRI  

SciTech Connect

Magnetic nanoparticles have recently been very attractive for biomedical applications. In this study, we have synthesized ferrite nanoparticles for application as contrast agents in MRI experiments. Fe{sub 3}O{sub 4} and MnFe{sub 2}O{sub 4} spinel ferrites with a mean size of 11-12 nm, were prepared by a modified polyol route in commercially available polyethylene glycol with molecular weight 600 (PEG-600). The reaction takes place in the presence of water soluble and non-toxic tri-block copolymer known as Pluronic registered F-127 (PEO{sub 100}-PPO{sub 65}-PEO{sub 100}). The nanoparticles have saturation magnetization values of 52 and 68 emu/g for MnFe{sub 2}O{sub 4} and Fe{sub 3}O{sub 4}, respectively. Both the Fe{sub 3}O{sub 4}, and MnFe{sub 2}O{sub 4} nanoparticles make stable solutions in water known as ferrofluids. Preliminary data demonstrated the capability of these nanoparticles to induce imaging contrast in T{sub 2} weighted MRI experiments, making these materials suitable for biomedical applications such as medical MRI.

Basina, Georgia [Institute of Materials Science, N.C.S.R. 'Demokritos' Agia Paraskevi 15310 Athens (Greece); Department of Physics and Astronomy, University of Delaware, DE 19716, Newark (United States); Tzitzios, Vasilis; Niarchos, Dimitris [Institute of Materials Science, N.C.S.R. 'Demokritos' Agia Paraskevi 15310 Athens (Greece); Li Wanfeng; Khurshid, Hafsa; Hadjipanayis, George [Department of Physics and Astronomy, University of Delaware, DE 19716, Newark (United States); Mao Hui [Department of Radiology, Emory University, School of Medicine, GA 30322, Atlanta (United States); Hadjipanayis, Costas [Department of Neurological Surgery, Emory University, School of Medicine, GA 30322, Atlanta (United States)

2010-12-02

330

Third-order nonlinear optical response of colloidal gold nanoparticles prepared by sputtering deposition  

SciTech Connect

The nonlinear optical responses of gold nanoparticles dispersed in castor oil produced by sputtering deposition were investigated, using the thermally managed Z-scan technique. Particles with spherical shape and 2.6 nm of average diameter were obtained and characterized by transmission electron microscopy and small angle X-ray scattering. This colloid was highly stable, without the presence of chemical impurities, neither stabilizers. It was observed that this system presents a large refractive third-order nonlinear response and a negligible nonlinear absorption. Moreover, the evaluation of the all-optical switching figures of merit demonstrated that the colloidal nanoparticles prepared by sputtering deposition have a good potential for the development of ultrafast photonic devices.

Castro, Hemerson P. S.; Alencar, Márcio A. R. C.; Hickmann, Jandir M. [Optics and Materials Group–OPTMA, Universidade Federal de Alagoas, CAIXA POSTAL 2051, 57061-970 Maceió (Brazil)] [Optics and Materials Group–OPTMA, Universidade Federal de Alagoas, CAIXA POSTAL 2051, 57061-970 Maceió (Brazil); Wender, Heberton [Brazilian Synchrotron National Laboratory (LNLS), CNPEM, Rua Giuseppe Máximo Scolfaro 10.000, 13083-970 Campinas (Brazil) [Brazilian Synchrotron National Laboratory (LNLS), CNPEM, Rua Giuseppe Máximo Scolfaro 10.000, 13083-970 Campinas (Brazil); Department of Physics, Universidade Federal do Mato Grosso do Sul, 79070-900, Campo Grande (Brazil); Teixeira, Sergio R. [Institute of Physics, Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre (Brazil)] [Institute of Physics, Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre (Brazil); Dupont, Jairton [Laboratory of Molecular Catalysis, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre (Brazil)] [Laboratory of Molecular Catalysis, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre (Brazil)

2013-11-14

331

Sonochemical method for preparation of copper indium sulfide nanoparticles and their application for solar cell.  

PubMed

In this paper, CuInS2 (CIS) nanoparticles were synthesized successfully via a new copper precursor [bis(acetylacetonato)copper(II)], [Cu(acac)2]; at room temperature by ultrasonic method. The effect of sulfur source, solvent, and reaction time was investigated on product morphology and particle size. A series of analyses was performed to characterize the CuInS2 microsphere including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. CuInS2 nanoparticles were prepared and coated on FTO. Later, the coated FTO was sintered so that a compact and dense CuInS2 film was produced and measured for photovoltaic characteristics such as Voc, Jsc and FF. PMID:23962129

Amiri, Omid; Salavati-Niasari, Masoud; Sabet, Mohammad; Ghanbari, Davood

2014-02-01

332

Surface engineered nanoparticles for improved surface enhanced Raman scattering applications and method for preparing same  

DOEpatents

A method for producing metal nanoparticles that when associated with an analyte material will generate an amplified SERS spectrum when the analyte material is illuminated by a light source and a spectrum is recorded. The method for preparing the metal nanoparticles comprises the steps of (i) forming a water-in-oil microemulsion comprising a bulk oil phase, a dilute water phase, and one or more surfactants, wherein the water phase comprises a transition metal ion; (ii) adding an aqueous solution comprising a mild reducing agent to the water-in-oil microemulsion; (iii) stirring the water-in-oil microemulsion and aqueous solution to initiate a reduction reaction resulting in the formation of a fine precipitate dispersed in the water-in-oil microemulsion; and (iv) separating the precipitate from the water-in-oil microemulsion.

Simmons, Blake A. (San Francisco, CA); Talin, Albert Alec (Livermore, CA)

2009-11-27

333

Preparation and characterization of silver nanoparticles on localized surface plasmon-enhanced optical absorption  

NASA Astrophysics Data System (ADS)

Self-assembly silver nanoparticles were successfully prepared on indium tin oxide coated glass substrates by means of a vacuum vapor evaporation method followed by thermal annealing. The nanoparticles were characterized using a field-emission scanning election microscopy with an energy dispersive X-ray analyzer and a UV-vis spectrometer. It was found that the particle morphology was drastically changed depending both on the evaporated silver mass thickness and the length of time of the thermal annealing. Some absorption peaks were observed in the UV-vis spectra and the peaks showed red-shift with the average particle size increase. These facts suggest that the absorption peaks may arise from the localized surface plasmon resonance. These controllable absorptions may be suitable for photon management in dye sensitized solar cells.

Mijanur Rahman, Md.; Hattori, Nampei; Nakagawa, Yuta; Lin, Xu; Yagai, Shiki; Sakai, Masatoshi; Kudo, Kazuhiro; Yamamoto, Kazunuki

2014-11-01

334

Predictive Toxicology of cobalt ferrite nanoparticles: comparative in-vitro study of different cellular models using methods of knowledge discovery from data  

PubMed Central

Background Cobalt-ferrite nanoparticles (Co-Fe NPs) are attractive for nanotechnology-based therapies. Thus, exploring their effect on viability of seven different cell lines representing different organs of the human body is highly important. Methods The toxicological effects of Co-Fe NPs were studied by in-vitro exposure of A549 and NCIH441 cell-lines (lung), precision-cut lung slices from rat, HepG2 cell-line (liver), MDCK cell-line (kidney), Caco-2 TC7 cell-line (intestine), TK6 (lymphoblasts) and primary mouse dendritic-cells. Toxicity was examined following exposure to Co-Fe NPs in the concentration range of 0.05 -1.2 mM for 24 and 72 h, using Alamar blue, MTT and neutral red assays. Changes in oxidative stress were determined by a dichlorodihydrofluorescein diacetate based assay. Data analysis and predictive modeling of the obtained data sets were executed by employing methods of Knowledge Discovery from Data with emphasis on a decision tree model (J48). Results Different dose–response curves of cell viability were obtained for each of the seven cell lines upon exposure to Co-Fe NPs. Increase of oxidative stress was induced by Co-Fe NPs and found to be dependent on the cell type. A high linear correlation (R2=0.97) was found between the toxicity of Co-Fe NPs and the extent of ROS generation following their exposure to Co-Fe NPs. The algorithm we applied to model the observed toxicity belongs to a type of supervised classifier. The decision tree model yielded the following order with decrease of the ranking parameter: NP concentrations (as the most influencing parameter), cell type (possessing the following hierarchy of cell sensitivity towards viability decrease: TK6 > Lung slices > NCIH441 > Caco-2?=?MDCK > A549 > HepG2?=?Dendritic) and time of exposure, where the highest-ranking parameter (NP concentration) provides the highest information gain with respect to toxicity. The validity of the chosen decision tree model J48 was established by yielding a higher accuracy than that of the well-known “naive bayes” classifier. Conclusions The observed correlation between the oxidative stress, caused by the presence of the Co-Fe NPs, with the hierarchy of sensitivity of the different cell types towards toxicity, suggests that oxidative stress is one possible mechanism for the toxicity of Co-Fe NPs. PMID:23895432

2013-01-01

335

New Method to Prepare Mitomycin C Loaded PLA-Nanoparticles with High Drug Entrapment Efficiency  

NASA Astrophysics Data System (ADS)

The classical utilized double emulsion solvent diffusion technique for encapsulating water soluble Mitomycin C (MMC) in PLA nanoparticles suffers from low encapsulation efficiency because of the drug rapid partitioning to the external aqueous phase. In this paper, MMC loaded PLA nanoparticles were prepared by a new single emulsion solvent evaporation method, in which soybean phosphatidylcholine (SPC) was employed to improve the liposolubility of MMC by formation of MMC-SPC complex. Four main influential factors based on the results of a single-factor test, namely, PLA molecular weight, ratio of PLA to SPC (wt/wt) and MMC to SPC (wt/wt), volume ratio of oil phase to water phase, were evaluated using an orthogonal design with respect to drug entrapment efficiency. The drug release study was performed in pH 7.2 PBS at 37 °C with drug analysis using UV/vis spectrometer at 365 nm. MMC-PLA particles prepared by classical method were used as comparison. The formulated MMC-SPC-PLA nanoparticles under optimized condition are found to be relatively uniform in size (594 nm) with up to 94.8% of drug entrapment efficiency compared to 6.44 ?m of PLA-MMC microparticles with 34.5% of drug entrapment efficiency. The release of MMC shows biphasic with an initial burst effect, followed by a cumulated drug release over 30 days is 50.17% for PLA-MMC-SPC nanoparticles, and 74.1% for PLA-MMC particles. The IR analysis of MMC-SPC complex shows that their high liposolubility may be attributed to some weak physical interaction between MMC and SPC during the formation of the complex. It is concluded that the new method is advantageous in terms of smaller size, lower size distribution, higher encapsulation yield, and longer sustained drug release in comparison to classical method.

Hou, Zhenqing; Wei, Heng; Wang, Qian; Sun, Qian; Zhou, Chunxiao; Zhan, Chuanming; Tang, Xiaolong; Zhang, Qiqing

2009-07-01

336

Preparation and Characterization of Selenium Incorporated Guar Gum Nanoparticle and Its Interaction with H9c2 Cells  

PubMed Central

This study deals with the preparation and characterization of selenium incorporated guar gum nanoparticle (SGG), and its effect on H9c2 cardiomyoblast. Herein, nanoprecipitation techniques had been employed for the preparation of SGG nanoparticle. The prepared nanoparticle had been subjected to various types of analytical techniques like transmission electron microscopy (TEM), X-ray diffraction (XRD) and particle size analysis to confirm the characteristics of nanoparticle as well as for selenium incorporation. Physical characterization of nanoparticle showed that the size of nanoparticles increase upto ?69–173 nm upon selenium incorporation from ?41–132 nm. Then the prepared nanoparticles were evaluated for its effect on H9c2 cells. In this regard, the effect of nanoparticle on various vital parameters of H9c2 cells was studied. Parameters like cell viability, uptake of selenium incorporated guar gum nanoparticle by the cells, effect of SGG on DNA integrity, apoptosis, reactive oxygen species generation, alteration in transmembrane potential of mitochondria and cytoskeletal integrity had been investigated. Viability results showed that up to 25 nM of SGG was safe (10.31%) but beyond that it induces cytotoxicity. Cellular uptake of selenium showed that cell permeability for SGG is significantly high compared to normal selenium (7.2 nM of selenium for 25 nM SGG compared with 5.2 nM selenium for 25 nM sodium selenite). There was no apoptosis with SGG and also it protects DNA from hydroxyl radical induced breakage. Likewise no adverse effect on mitochondria and cytoskeleton was observed for 25 nM of SGG. Overall results reveal that SGG is highly suitable for biomedical research application. PMID:24098647

Soumya, Rema Sreenivasan; Vineetha, Vadavanath Prabhakaran; Reshma, Premachandran Latha; Raghu, Kozhiparambil Gopalan

2013-01-01

337

Optical properties of highly crystalline Y2O3:Er,Yb nanoparticles prepared by laser ablation in water  

NASA Astrophysics Data System (ADS)

Y2O3:Er,Yb nanoparticles were prepared by laser ablation in water. We investigated crystallinity, distribution of dopant, and optical properties of the prepared nanoparticles. The full-width half-maximum (FWHD) of the crystalline peak of nanoparticles measured by an x-ray diffractometer (XRD) barely changed. Further, using scanning transmission electron microscopy–energy dispersive x-ray spectroscopy (STEM–EDX), we confirmed the peaks of Y, Er, Yb, and O. Moreover, on the basis of the optical properties of the nanoparticles, the emission of red (2F9/2 → 4I15/2) and green (2H11/2, 4S3/2 → 4I15/2) was confirmed. We also investigated the emission intensity as a function of the excitation power of 980 nm LD in the prepared nanoparticles. The photon avalanche effect was observed at the excitation power of 100 mW. These results confirmed that uniformly Er-Yb-doped Y2O3 nanoparticles were successfully prepared by laser ablation in water.

Nunokawa, Takashi; Odawara, Osamu; Wada, Hiroyuki

2014-09-01

338

Toxicity of citrate-coated silver nanoparticles differs according to method of suspension preparation.  

PubMed

To evaluate substance toxicity, it is critical to maintain specific concentrations of test substances throughout the exposure period. During the last decade, the need to improve methods for nanoparticle (NP) suspension preparations has gained attention because many published results on NPs toxicity have been inconsistent. Here, we compared the toxicity of citrate-coated silver nanoparticles (AgNPs) suspended by two different methods (fractionated vs. colloidal) in freshwater organisms (daphnia and medaka). Analytical methods (ICP-OES, DLS and UV absorbance) were employed to characterize behavior of AgNPs in suspension. Results showed that fractionated (stirred and settled) solution was less toxic to daphnia (13.8 µg/L) than colloidal solution (6.1 µg/L), suggesting that method of preparation was a critical factor that affected toxicity. However, differences in toxicity caused by suspension methods were not observed in medaka. Results indicate that the method used to prepare suspensions of NPs can affect toxicity, and that differences can exist among test organisms. PMID:24841540

Park, June-Woo; Oh, Ji-Hyun; Kim, Woo-Keun; Lee, Sung-Kyu

2014-07-01

339

Facile approach for preparation of stable water-repellent nanoparticle coating  

NASA Astrophysics Data System (ADS)

The present study reports a very simple and low-cost dip-coating method for the preparation of fluorine-free water-repellent SiO2 nanoparticle coating. The coating has a high water contact angle of 169° and a sliding angle of 7°, showing superhydrophobic property. The coating demonstrates good adhesion on substrates and the long-term stability. Importantly, the coating also demonstrates superhydrophobicity in the wide pH range of corrosive liquids. It is found that a piece of glass coated with superhydrophobic coatings cannot only float freely on water surface but also exhibit striking loading capacities.

Zhang, Xia; Guo, Yonggang; Zhang, Zhijun; Zhang, Pingyu

2012-08-01

340

Influences of surfactants on the preparation of copper nanoparticles by electron beam irradiation  

NASA Astrophysics Data System (ADS)

Electron beam radiation was applied to prepare nano-size copper in water system using polyvinyl alcohol, sodium dodecyl benzene sulfonate, gluten and polyethylene glycol as the surfactants, respectively. The irradiated products were characterized by XRD, TEM and LSPSDA. The XRD and TEM showed that relative pure copper products with an average size of 20 nm, 40 nm and 20 nm can be obtained by using gluten, PEG and SDBS as surfactant, respectively. An admixture of copper and cuprous oxide was obtained in PVA system. The LSPSDA showed that the size of the Cu nanoparticles decreased with increasing the glutin concentration.

Zhou, Ruimin; Wu, Xinfeng; Hao, Xufeng; Zhou, Fei; Li, Hongbin; Rao, Weihong

2008-02-01

341

A New Method of Preparation of Magnetite Nanoparticles from Iron Oxide Hydroxide  

NASA Astrophysics Data System (ADS)

There are only two basic ways to produce magnetite at low temperature: by partial oxidation of a FeII salt solution with oxidant under alkaline condition and by precipitation of a mixed FeII/FeIII solution. At high temperature, the method involves reduction of iron oxide by a suitable reductant. Here we propose a new method of preparation of nanoparticle Fe3O4 from iron oxyhydroxides (goethite, akaganeite, lepidocrocite, feroxyhyte and ferrihydrite) or iron oxide (hematite) and ferrous salt in aqueous solution. Products characterized by X-ray powder diffraction, IR spectra and vibrating sample magentometery.

Kahani, S. A.; Jafari, M.

2007-08-01

342

Preparation of silver nanoparticles/graphene nanosheets as a catalyst for electrochemical oxidation of methanol  

NASA Astrophysics Data System (ADS)

In this report, silver nanoparticles (AgNPs) decorated graphene nanosheets have been prepared based on the reduction of Ag ions by hydroquinone, and their catalytic performance towards the electrochemical oxidation of methanol is investigated. The synthesis of the nano-composite is confirmed by transmission electron microscope measurements and UV-vis absorption spectra. Excellent electrocatalytic performance of the material is demonstrated by cyclic voltammograms. This material also contributes to the low peak potential of methanol oxidation compared with most of the other materials.

Han, Kun; Miao, Peng; Tong, Hui; Liu, Tao; Cheng, Wenbo; Zhu, Xiaoli; Tang, Yuguo

2014-02-01

343

Preparation of poly(?-caprolactone)-based polyurethane nanofibers containing silver nanoparticles  

Microsoft Academic Search

In this study, poly(?-caprolactone)-based polyurethane (PCL-PU) nanofibers containing Ag nanoparticles for use in antimicrobial nanofilter applications were prepared by electrospinning 8wt% PCL-PU solutions containing different amounts of AgNO3 in a mixed solvent consisting of DMF\\/THF (7\\/3w\\/w). The average diameter of the pure PCL-PU nanofibers was 560nm and decreased with increasing concentration of AgNO3. The PCL-PU nanofiber mats electrospun with AgNO3

Hyun Jeong Jeon; Jin Sook Kim; Tae Gon Kim; Jung Hyun Kim; Woong-Ryeol Yu; Ji Ho Youk

2008-01-01

344

Water- and organo-dispersible gold nanoparticles supported by using ammonium salts of hyperbranched polystyrene: preparation and catalysis.  

PubMed

Gold nanoparticles (1 nm in size) stabilized by ammonium salts of hyperbranched polystyrene are prepared. Selection of the R groups provides access to both water- and organo-dispersible gold nanoparticles. The resulting gold nanoparticles are subjected to studies on catalysis in solution, which include reduction of 4-nitrophenol with sodium borohydride, aerobic oxidation of alcohols, and homocoupling of phenylboronic acid. In the reduction of 4-nitrophenol, the catalytic activity is clearly dependent on the size of the gold nanoparticles. For the aerobic oxidation of alcohols, two types of biphasic oxidation are achieved: one is the catalyst dispersing in the aqueous phase, whereas the other is in the organic phase. The catalysts are reusable more than four times without loss of the catalytic activity. Selective synthesis of biphenyl is achieved by the homocoupling of phenylboronic acid catalyzed by organo-dispersible gold nanoparticles. PMID:24115377

Gao, Lei; Nishikata, Takashi; Kojima, Keisuke; Chikama, Katsumi; Nagashima, Hideo

2013-12-01

345

Recyclable nano-size Pd catalyst generated in the multilayer polyelectrolyte films on the magnetic nanoparticle core  

Microsoft Academic Search

This work describes the preparation of Pd nanoparticles in multilayer polyelectrolyte films fabricated on a magnetic ferrite core by a layer-by-layer (LbL) self-assembly technique, and the relationship between catalytic activity and these hybrid core-shell nanocomposite structures in the hydrogenation of olefinic alcohols. The hydrogenation reaction seems to be only catalyzed by Pd nanoparticles in the outermost layer of the hybrid

Yuhong Wang; Jin-Kyu Lee

2007-01-01

346

Size dependence of the magnetic properties of Ni nanoparticles prepared by thermal decomposition method  

PubMed Central

By means of thermal decomposition, we prepared single-phase spherical Ni nanoparticles (23 to 114 nm in diameter) that are face-centered cubic in structure. The magnetic properties of the Ni nanoparticles were experimentally as well as theoretically investigated as a function of particle size. By means of thermogravimetric/differential thermal analysis, the Curie temperature TC of the 23-, 45-, 80-, and 114-nm Ni particles was found to be 335°C, 346°C, 351°C, and 354°C, respectively. Based on the size-and-shape dependence model of cohesive energy, a theoretical model is proposed to explain the size dependence of TC. The measurement of magnetic hysteresis loop reveals that the saturation magnetization MS and remanent magnetization increase and the coercivity decreases monotonously with increasing particle size, indicating a distinct size effect. By adopting a simplified theoretical model, we obtained MS values that are in good agreement with the experimental ones. Furthermore, with increase of surface-to-volume ratio of Ni nanoparticles due to decrease of particle size, there is increase of the percentage of magnetically inactive layer. PMID:24164907

2013-01-01

347

Preparation and near-infrared photothermal conversion property of cesium tungsten oxide nanoparticles  

PubMed Central

Cs0.33WO3 nanoparticles have been prepared successfully by a stirred bead milling process. By grinding micro-sized coarse powder with grinding beads of 50 ?m in diameter, the mean hydrodynamic diameter of Cs0.33WO3 powder could be reduced to about 50 nm in 3 h, and a stable aqueous dispersion could be obtained at pH 8 via electrostatic repulsion mechanism. After grinding, the resulting Cs0.33WO3 nanoparticles retained the hexagonal structure and had no significant contaminants from grinding beads. Furthermore, they exhibited a strong characteristic absorption and an excellent photothermal conversion property in the near-infrared (NIR) region, owing to the free electrons or polarons. Also, the NIR absorption and photothermal conversion property became more significant with decreasing particle size or increasing particle concentration. When the concentration of Cs0.33WO3 nanoparticles was 0.08 wt.%, the solution temperature had a significant increase of above 30°C in 10 min under NIR irradiation (808 nm, 2.47 W/cm2). In addition, they had a photothermal conversion efficiency of about 73% and possessed excellent photothermal stability. Such an effective NIR absorption and photothermal conversion nanomaterial not only was useful in the NIR shielding, but also might find great potential in biomedical application. PMID:23379652

2013-01-01

348

Highly conductive ribbons prepared by stick-slip assembly of organosoluble gold nanoparticles.  

PubMed

Precisely positioning and assembling nanoparticles (NPs) into hierarchical nanostructures is opening opportunities in a wide variety of applications. Many techniques employed to produce hierarchical micrometer and nanoscale structures are limited by complex fabrication of templates and difficulties with scalability. Here we describe the fabrication and characterization of conductive nanoparticle ribbons prepared from surfactant-free organosoluble gold nanoparticles (Au NPs). We used a flow-coating technique in a controlled, stick-slip assembly to regulate the deposition of Au NPs into densely packed, multilayered structures. This affords centimeter-scale long, high-resolution Au NP ribbons with precise periodic spacing in a rapid manner, up to 2 orders-of-magnitude finer and faster than previously reported methods. These Au NP ribbons exhibit linear ohmic response, with conductivity that varies by changing the binding headgroup of the ligands. Controlling NP percolation during sintering (e.g., by adding polymer to retard rapid NP coalescence) enables the formation of highly conductive ribbons, similar to thermally sintered conductive adhesives. Hierarchical, conductive Au NP ribbons represent a promising platform to enable opportunities in sensing, optoelectronics, and electromechanical devices. PMID:24417627

Lawrence, Jimmy; Pham, Jonathan T; Lee, Dong Yun; Liu, Yujie; Crosby, Alfred J; Emrick, Todd

2014-02-25

349

Preparation of crystalline starch nanoparticles using cold acid hydrolysis and ultrasonication.  

PubMed

Waxy maize starch in an aqueous sulfuric acid solution (3.16 M, 14.7% solids) was hydrolyzed for 2-6 days, either isothermally at 40 °C or 4 °C, or at cycled temperatures of 4 and 40 °C (1 day each). The starch hydrolyzates were recovered as precipitates after centrifuging the dispersion (10,000 rpm, 10 min). The yield of starch hydrolyzates depended on the hydrolysis temperature and time, which varied from 6.8% to 78%. The starch hydrolyzed at 40 °C or 4/40 °C exhibited increased crystallinity determined by X-ray diffraction analysis, but melted in broader temperature range (from 60 °C to 110 °C). However, the starch hydrolyzed at 4 °C displayed the crystallinity and melting endotherm similar to those of native starch. The starch hydrolyzates recovered by centrifugation were re-dispersed in water (15% solids), and the dispersion was treated by an ultrasonic treatment (60% amplitude, 3min). The ultrasonication effectively fragmented the starch hydrolyzates to nanoparticles. The hydrolyzates obtained after 6 days of hydrolysis were more resistant to the ultrasonication than those after 2 or 4 days, regardless of hydrolysis temperatures. The starch nanoparticles could be prepared with high yield (78%) and crystallinity by 4 °C hydrolysis for 6 days followed by ultrasonication. Scanning electron microscopy revealed that the starch nanoparticles had globular shapes with diameters ranging from 50 to 90 nm. PMID:23987348

Kim, Hee-Young; Park, Dong June; Kim, Jong-Yea; Lim, Seung-Taik

2013-10-15

350

Preparation of copper nanoparticles coated cellulose films with antibacterial properties through one-step reduction.  

PubMed

Regenerated cellulose (RC) films coated with copper (Cu) nanoparticles were prepared from cellulose-cuprammonium solution through coagulation in aq. NaOH and subsequent reduction in aq. NaBH4. Structure and morphology of the nanocomposite films were characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The results established the migration of Cu(2+) from the inner to the surface of the RC films during the coagulation of cellulose-cuprammonium solution and the reduction from Cu(2+) to Cu(0). Cu nanoparticles were found to be firmly embedded on the surface of the RC films. The RC films coated with Cu nanoparticles showed efficient antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The dramatic reduction of viable bacteria could be observed within 0.5 h of exposure, and all of the bacteria were killed within 1 h. PMID:22680307

Jia, Baoquan; Mei, Yan; Cheng, Li; Zhou, Jinping; Zhang, Lina

2012-06-27

351

Nonaqueous synthesis of metal oxide nanoparticles: Short review and doped titanium dioxide as case study for the preparation of transition metal-doped oxide nanoparticles  

SciTech Connect

The liquid-phase synthesis of metal oxide nanoparticles in organic solvents under exclusion of water is nowadays a well-established alternative to aqueous sol-gel chemistry. In this article, we highlight some of the advantages of these routes based on selected examples. The first part reviews some recent developments in the synthesis of ternary metal oxide nanoparticles by surfactant-free nonaqueous sol-gel routes, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the presentation of structural peculiarities of manganese oxide nanoparticles with an ordered Mn vacancy superstructure. These examples show that nonaqueous systems, on the one hand, allow the preparation of compositionally complex oxides, and, on the other hand, make use of the organic components (initially present or formed in situ) in the reaction mixture to tailor the morphology. Furthermore, obviously even the crystal structure can differ from the corresponding bulk material like in the case of MnO nanoparticles. In the second part of the paper we present original results regarding the synthesis of dilute magnetic semiconductor TiO{sub 2} nanoparticles doped with cobalt and iron. The structural characterization as well as the magnetic properties with special attention to the doping efficiency is discussed. - Graphical abstract: In the first part of this article, nonaqueous sol-gel routes to ternary metal oxide nanoparticles are briefly reviewed, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the appearance of an unprecedented superstructure in MnO nanoparticles. In the second part, doping experiments of TiO{sub 2} with Fe and Co are presented, along with their characterization including magnetic measurements.

Djerdj, Igor [ETH Zuerich, Department of Materials, Wolfgang-Pauli-Strasse 10, 8093 Zuerich (Switzerland)], E-mail: igor.djerdj@mat.ethz.ch; Arcon, Denis [Institute Jozef Stefan, Jamova 39, 1000 Ljubljana (Slovenia); Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Jaglicic, Zvonko [Institute of Mathematics, Physics and Mechanics, Jadranska 19, 1000 Ljubljana (Slovenia); Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova 2, 1000 Ljubljana (Slovenia); Niederberger, Markus [ETH Zuerich, Department of Materials, Wolfgang-Pauli-Strasse 10, 8093 Zuerich (Switzerland)], E-mail: markus.niederberger@mat.ethz.ch

2008-07-15

352

Preparation, structural characterization, semiconductor and photoluminescent properties of zinc oxide nanoparticles in a phosphonium-based ionic liquid  

Microsoft Academic Search

A convenient microwave method in preparation of zinc oxide nanoparticles (ZnONPs) using an ionic liquid, trihexyltetradecylphosphonium bis{(trifluoromethyl)sulfonyl}-imide, [P66614][NTf2], as a green solvent is described in this paper. To the best of our knowledge, there is no report for synthesizing any nanoparticle using this ionic liquid. Trihexyltetradecylphosphonium bis{(trifluoromethyl)sulfonyl}-imide has low interface tension and thus it can enhance the nucleation rate, which

Elaheh K. Goharshadi; Maryam Abareshi; Roya Mehrkhah; Sara Samiee; Majid Moosavi; Abbas Youssefi; Paul Nancarrow

2011-01-01

353

Preparation, Optimization and Thermal Characterization of a Novel Conductive Thermoset Nanocomposite Containing Polythiophene Nanoparticles Using Dynamic Thermal Analysis  

Microsoft Academic Search

Polythiophene nanoparticles as a conductive filler was prepared with average diameter of 20–35 nm and its molecular structure was confirmed by the FTIR, TEM, XRD and UV-Vis analysis. A new conductive epoxy nanocomposite was synthesized by curing of diglycidyl ether of bisphenol A\\/ 4,4?-(4,4? Isopropylidenediphenoxy) bis (Phthalic Anhydride) involving various percentages of polythiophene nanoparticles. DSC and DMTA studies revealed that

Omid Zabihi; Aminreza Khodabandeh; S. Mojtaba Mostafavi

354

In vitro degradation of nanoparticles prepared from polymers based on dl-lactide, glycolide and poly(ethylene oxide)  

Microsoft Academic Search

Nanoparticles of poly(dl-lactic acid) (PDLLA), poly(dl-lactic-co-glycolic acid) (PLGA) and poly(ethylene oxide)–PLGA diblock copolymer (PEO–PLGA) were prepared by the salting-out method. The in vitro degradation of PDLLA, PLGA and PEO–PLGA nanoparticles in PBS (pH 7.4) at 37 °C was studied. The particle size, molecular weight of the polymers and the amount of lactic and glycolic acids formed were followed in time.

Miechel L. T. Zweers; Gerard H. M. Engbers; Dirk W. Grijpma; Jan Feijen

2004-01-01

355

Preparation of Silver Nanoparticles from Synthetic and Natural Sources: Remediation Model for PAHs  

NASA Astrophysics Data System (ADS)

The emergence of nanoscience and technology is gaining popularity with an increasing demand for metal nanoparticles applicability in various areas such as electronics, catalysis, chemistry, energy and medicine. Metallic nanoparticles are traditionally synthesized by wet chemical techniques, where the chemicals used are quite often toxic and flammable. In this work, an attempt is made to compare the efficiency of two different synthesis methods and application of each for the remediation of poly aromatic hydrocarbons (PAHs). In this regard, silver nanoparticles are prepared by green and wet chemical method using plant extract of garlic (Allium sativum). The extract is known to reduce the metal during synthesis and acts as stabilizing ligand. These synthesized silver nanoparticles (Agp) and (AgW) were applied as adsorbents in synthetic batch mode experiments at varying parameters of pH and temperature. A concentration of 0.01mg/L of Phenanthrene, Anthracene, and Pyrene were induced at fixed dosage of 1mg/Kg of adsorbent. Residual concentration of each PAH was analyzed on UV-Visible spectrophotometer. The results indicated that both adsorbents follow the sequence of Phenanthrene>Pyrene>Anthracene with optimal removal of higher than 85% in each case. A distinguishing privilege is attained by Agp adsorbent showing 3, 3 and 11 orders of magnitude higher efficiency than Agw. It may be attributed to more functional groups in the plant extract participating in binding of PAH to the surface. Each synthesized adsorbents was characterized by FTIR, SEM and EDX. The average particle size was determined to be of the order of 13-26 nm. The study concludes the use of alternate economical and green adsorbents for control of poly aromatic hydrocarbons (PAHs).

Abbasi, Maryam; Saeed, Fatima; Rafique, Uzaira

2014-06-01

356

Preparation and characterization of solid lipid nanoparticles containing cyclosporine by the emulsification-diffusion method  

PubMed Central

Solid lipid nanoparticles (SLNs) have been used for carrying different therapeutic agents because they improve absorption and bioavailability. The aim of the study was to prepare lipidic nanoparticles containing cyclosporine (CyA) by the emulsification-diffusion method and to study their physicochemical stability. Glyceryl behenate (Compritol® ATO 888) and lauroyl macrogolglycerides (Gelucire® 44/14) were used as carrier materials. Nanoparticles with good stability were obtained with Gelucire®, while it was difficult to obtain stable systems with Compritol®. Systems with Gelucire® were characterized by particle size, Z-potential, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), entrapment efficiency and in vitro release. Particle size and Z-potential were evaluated for at least three months. With a high CyA content (?60 mg) in Gelucire® SLNs, variations in size were greater and particle size also increased over time in all batches; this effect may have been caused by a probable expulsion of the drug due to the lipid’s partial rearrangement. While the Z-potential decreased 10 mV after three months, this effect may be explained by the superficial properties of the drug that make the molecules to be preferably oriented at the solid-liquid interface, causing a change in the net charge of the particle. SEM confirmed size and shape of the nanoparticles. DSC studies evidenced that CyA affects the lipid structure by a mechanism still unknown. The entrapment efficiency was higher than 92%, and CyA release from SLNs was relatively fast (99.60% in 45 min). PMID:20856836

Urban-Morlan, Zaida; Ganem-Rondero, Adriana; Melgoza-Contreras, Luz Maria; Escobar-Chavez, Jose Juan; Nava-Arzaluz, Maria Guadalupe; Quintanar-Guerrero, David

2010-01-01

357

Comparative studies of salinomycin-loaded nanoparticles prepared by nanoprecipitation and single emulsion method  

PubMed Central

To establish a satisfactory delivery system for the delivery of salinomycin (Sal), a novel, selective cancer stem cell inhibitor with prominent toxicity, gelatinase-responsive core-shell nanoparticles (NPs), were prepared by nanoprecipitation method (NR-NPs) and single emulsion method (SE-NPs). The gelatinase-responsive copolymer was prepared by carboxylation and double amination method. We studied the stability of NPs prepared by nanoprecipitation method with different proportions of F68 in aqueous phase to determine the best proportion used in our study. Then, the NPs were prepared by nanoprecipitation method with the best proportion of F68 and single emulsion method, and their physiochemical traits including morphology, particle size, zeta potential, drug loading content, stability, and in vitro release profiles were studied. The SE-NPs showed significant differences in particle size, drug loading content, stability, and in vitro release profiles compared to NR-NPs. The SE-NPs presented higher drug entrapment efficiency and superior stability than the NR-NPs. The drug release rate of SE-NPs was more sustainable than that of the NR-NPs, and in vivo experiment indicated that NPs could prominently reduce the toxicity of Sal. Our study demonstrates that the SE-NPs could be a satisfactory method for the preparation of gelatinase-responsive NPs for intelligent delivery of Sal. PMID:25147486

2014-01-01

358

Comparative studies of salinomycin-loaded nanoparticles prepared by nanoprecipitation and single emulsion method.  

PubMed

To establish a satisfactory delivery system for the delivery of salinomycin (Sal), a novel, selective cancer stem cell inhibitor with prominent toxicity, gelatinase-responsive core-shell nanoparticles (NPs), were prepared by nanoprecipitation method (NR-NPs) and single emulsion method (SE-NPs). The gelatinase-responsive copolymer was prepared by carboxylation and double amination method. We studied the stability of NPs prepared by nanoprecipitation method with different proportions of F68 in aqueous phase to determine the best proportion used in our study. Then, the NPs were prepared by nanoprecipitation method with the best proportion of F68 and single emulsion method, and their physiochemical traits including morphology, particle size, zeta potential, drug loading content, stability, and in vitro release profiles were studied. The SE-NPs showed significant differences in particle size, drug loading content, stability, and in vitro release profiles compared to NR-NPs. The SE-NPs presented higher drug entrapment efficiency and superior stability than the NR-NPs. The drug release rate of SE-NPs was more sustainable than that of the NR-NPs, and in vivo experiment indicated that NPs could prominently reduce the toxicity of Sal. Our study demonstrates that the SE-NPs could be a satisfactory method for the preparation of gelatinase-responsive NPs for intelligent delivery of Sal. PMID:25147486

Wang, Qin; Wu, Puyuan; Ren, Wei; Xin, Kai; Yang, Yang; Xie, Chen; Yang, Chenchen; Liu, Qin; Yu, Lixia; Jiang, Xiqun; Liu, Baorui; Li, Rutain; Wang, Lifeng

2014-01-01

359

Nanoparticles prepared from porous silicon nanowires for bio-imaging and sonodynamic therapy  

PubMed Central

Evaluation of cytotoxicity, photoluminescence, bio-imaging, and sonosensitizing properties of silicon nanoparticles (SiNPs) prepared by ultrasound grinding of porous silicon nanowires (SiNWs) have been investigated. SiNWs were formed by metal (silver)-assisted wet chemical etching of heavily boron-doped (100)-oriented single crystalline silicon wafers. The prepared SiNWs and aqueous suspensions of SiNPs exhibit efficient room temperature photoluminescence (PL) in the spectral region of 600 to 1,000 nm that is explained by the radiative recombination of excitons confined in small silicon nanocrystals, from which SiNWs and SiNPs consist of. On the one hand, in vitro studies have demonstrated low cytotoxicity of SiNPs and possibilities of their bio-imaging applications. On the other hand, it has been found that SiNPs can act as efficient sensitizers of ultrasound-induced suppression of the viability of Hep-2 cancer cells. PMID:25288909

2014-01-01

360

Time-dependent preparation of gelatin-stabilized silver nanoparticles by pulsed Nd:YAG laser  

NASA Astrophysics Data System (ADS)

Colloidal silver nanoparticles (Ag-NPs) were successfully prepared using a nanosecond pulsed Nd:YAG laser, ? = 1064 nm, with laser fluence of approximately about 360 mJ/pulse, in an aqueous gelatin solution. In this work, gelatin was used as a stabilizer, and the size and optical absorption properties of samples were studied as a function of the laser ablation times. The results from the UV-vis spectroscopy demonstrated that the mean diameter of Ag-NPs decrease as the laser ablation time increases. The Ag-NPs have mean diameters ranging from approximately 10 nm to 16 nm. Compared with other preparation methods, this work is clean, rapid, and simple to use.

Darroudi, Majid; Ahmad, M. B.; Zamiri, Reza; Abdullah, A. H.; Ibrahim, N. A.; Sadrolhosseini, A. R.

2011-03-01

361

NOVEL PREPARATION AND MAGNETO CHEMICAL CHARACTERIZATION OF NANOPARTICLE MIXED ALCOHOL CATALYSTS  

SciTech Connect

We have developed and streamlined the experimental systems: (a) Laser-induced solution deposition (LISD) photosynthesis, ball-milling, and chemical synthesis of Fe, Co, and Cu nanoparticle catalysts; (b) Sol-gel method for mesoporous {gamma}-Al{sub 2}O{sub 3}, SiO{sub 2}, hybrid alumina/silica granular supports; (c) Three sol-gel/oil-drop catalyst preparation methods to incorporate metal nanoparticles into mesoporous 1 mm granular supports; (d) Low-cost GC-TCD system with hydrogen as carrier gas for the determination of wide spectrum of alkanes produced during the F-T reactions; and (e) Gas-flow reactor and microchannel reactor for fast screening of catalysts. The LISD method could produce Co, Cu, and Fe (5 nm) nanoparticles, but in milligram quantities. We could produce nanoparticles in gram quantities using high-energy ball milling and chemical synthesis methods. Ball milling gave wide particle size distribution compared to the chemical synthesis method that gave almost uniform size ({approx}5 nm) particles. Metal nanoparticles Cu, Co, Fe, Cu/Co, Cu/Fe and Co/Fe were loaded (2-12 wt%) uniformly into {gamma}-Al{sub 2}O{sub 3}, SiO{sub 2}, or alumina/silica hybrid supports by combined sol-gel/oil-drop methods followed by calcination and hydrogenation steps, prior to syngas FT reaction studies. The properties of metal loaded {gamma}-Al{sub 2}O{sub 3} granules were compared for the two precursors: aluminum tri-sec-butoxide (ALTSB) and aluminum tri-iso-propoxide (ALTIP). The effect of solgel supports alumina, silica, and alumina/silica hybrid were examined on catalytic properties. Metal loading efficiencies for pure metal catalysts increased in the order Co, Cu and Fe in agreement with solubility of metal hydroxides. In case of mixed metals, Co and Cu seams to interfere and reduce Fe metal loading when metal nitrate solutions are used. The solubility differences of metal hydroxides would not allow precise control of metal loading. We have overcome this problem by introducing a novel method of nanoparticle metal oxide co-entrapped sol-gel that gave the highest metal loading with precise control and reproducibility, and greater mechanical strength of granules than the metal nitrate solution co-entrapping and wet impregnation methods. Both, slurry-phase-batch and gas-phase-continuous-flow, reactors were used for syngas conversion reactions. Our investigations of Co and Fe thin film deposited micro-reactors showed higher CO/H{sub 2} conversion for Fe compared to Co. The catalytic activity for CO/H{sub 2} conversion was observed in the increasing order for the nanocatalysts Cu, Co, Fe, Co/Fe, Cu/Co and Cu/Fe in alumina sol-gel support, and Co/Fe showed the highest yield for methane. The optimization of CO/H{sub 2} ratio indicated that 1:1 ratio gave more alkanes distribution in F-T process with Co/Fe (6% each) impregnated on alumina. We could estimate the activity of catalysts (involving Co, Fe) during hydrogenation and after catalytic reaction using magnetization studies. In summary our accomplishments are: (1) Novel chemical methods for the synthesis of (5 nm) Fe, Co, Cu nanoparticles with narrow size distribution. (2) Developing a method of metal oxide nanoparticles addition to alumina/silica sol-gel to control metal loading of pure and mixed metal catalysts compositions in high yields. (3) A low-cost GC-TCD system to analyze wide spectrum of alkanes (F-T reaction products). (4) Fe/Co mixed metal alumina/silica mesoporous catalysts with higher FT activity. (5) Characterizing nanoparticle catalysts and supports for detail understanding of FT-process.

Seetala V. Naidu; Upali Siriwardane

2005-05-24

362

Preparation and evaluation of tilmicosin-loaded hydrogenated castor oil nanoparticle suspensions of different particle sizes  

PubMed Central

Three tilmicosin-loaded hydrogenated castor oil nanoparticle (TMS-HCO-NP) suspensions of different particle sizes were prepared with different polyvinyl alcohol surfactant concentrations using a hot homogenization and ultrasonic technique. The in vitro release, in vitro antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability study were conducted to evaluate the characteristics of the suspensions. The in vitro tilmicosin release rate, antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability of the suspensions were evaluated. When prepared with polyvinyl alcohol concentrations of 0.2%, 1%, and 5%, the mean diameters of the nanoparticles in the three suspensions were 920±35 nm, 452±10 nm, and 151±4 nm, respectively. The three suspensions displayed biphasic release profiles similar to that of freeze-dried TMS-HCO-NP powders, with the exception of having a faster initial release. Moreover, suspensions of smaller-sized particles showed faster initial release, and lower minimum inhibitory concentrations and minimum bactericidal concentrations. Time-kill curves showed that within 12 hours, the suspension with the 151 nm particles had the most potent bactericidal activity, but later, the suspensions with larger-sized particles showed increased antibacterial activity. None of the three suspensions were cytotoxic at clinical dosage levels. At higher drug concentrations, all three suspensions showed similar concentration-dependent cytotoxicity. The suspension with the smallest-sized particle showed significantly more acute toxicity in mice, perhaps due to faster drug release. All three suspensions exhibited good stability at 4°C and at room temperature for at least 6 months. These results demonstrate that TMS-HCO-NP suspensions can be a promising formulation for tilmicosin, and that nanoparticle size can be an important consideration for formulation development. PMID:24920902

Chen, Xiaojin; Wang, Ting; Lu, Mengmeng; Zhu, Luyan; Wang, Yan; Zhou, WenZhong

2014-01-01

363

Physical properties of nanoparticle silica gel doped with CdS prepared by sol-gel technique  

NASA Astrophysics Data System (ADS)

CdS/silica xerogel glasses were prepared via silica gels containing mixture solution of 0.2 M (CdCl2 and thiourea) with molar ratio 1:1. Doping the gels with this mixture solution and its heat treatment gave transparent yellow silica-gel glasses doped with CdS crystals. X-ray diffraction and transmission electron microscope make it possible to evaluate the nanoparticle size of the prepared samples. The nanoparticle size was dependent on the concentration of the dopant materials and the heating temperature. In the optical transmission spectra, the absorption edge exhibited a blue shift compared to that of the bulk CdS, and its energy shift was reciprocally proportional to the square of the radius. Thus the quantum-size effect could be found for the silica gel containing CdS prepared by the sol-gel process. The energy band gap shifted to higher energy for smaller nanoparticle size.

Battisha, I. K.

364

Preparation of 5-fluorouracil nanoparticles by supercritical antisolvents for pulmonary delivery  

PubMed Central

This study concerns the supercritical antisolvent process which allows single-step production of 5-fluorouracil (5-FU) nanoparticles. This process enhances the physical characteristics of 5-FU in order to deliver it directly to the respiratory tract. Several mixtures of methanol with dichloromethane, acetone, or ethanol were used for particle preparation, and their effects on the physical characteristics of the final products were studied. The conditions of the experiment included pressures of 100 and 150 bar, temperature of 40°C, and a flow rate of 1 mL/min. The particles were characterized physicochemically before and after the process for their morphology and crystallinity. In spite of differences in size, the particles were not very different regarding their morphology. The resulting particles were of a regular shape, partly spherical, and appeared to have a smooth surface, whereas the mechanically milled particles showed less uniformity, had surface irregularities and a high particle size distribution, and seemed aggregated. Particles of 5-FU precipitated from methanol-dichloromethane 50:50 had a mean particle size of 248 nm. In order to evaluate the aerodynamic behavior of the nanoparticles, six 5-FU dry powder formulations containing mixtures of coarse and fine lactose of different percentages were prepared. Deposition of 5-FU was measured using a twin-stage liquid impinger and analyzed using a validated high pressure liquid chromatography method. Addition of fine lactose improved the aerodynamic performance of the drug, as determined by the fine particle fraction. PMID:21042422

Kalantarian, Pardis; Najafabadi, Abdolhosein Rouholamini; Haririan, Ismaeil; Vatanara, Alireza; Yamini, Yadollah; Darabi, Majid; Gilani, Kambiz

2010-01-01

365

Preparation and efficacy of Newcastle disease virus DNA vaccine encapsulated in chitosan nanoparticles.  

PubMed

Optimal preparation conditions of Newcastle disease virus (NDV) F gene deoxyribonucleic acid (DNA) vaccine encapsulated in chitosan nanoparticles (pFNDV-CS-NPs) were determined. The pFNDV-CS-NPs were prepared according to a complex coacervation method. The pFNDV-CS-NPs were produced with good morphology, high stability, a mean diameter of 199.5 nm, encapsulation efficiency of 98.37% ± 0.87%, loading capacity of 36.12% ± 0.19%, and a zeta potential of +12.11 mV. The in vitro release assay showed that the plasmid DNA was sustainably released from the pFNDV-CS-NPs, up to 82.9% ± 2.9% of the total amount. Cell transfection test indicated that the vaccine expressed the F gene in cells and maintained good bioactivity. Additionally, the safety of mucosal immunity delivery system of the pFNDV-CS-NPs was also tested in vitro by cell cytotoxicity and in vivo by safety test in chickens. In vivo immunization showed that better immune responses of specific pathogen-free chickens immunized with the pFNDV-CS-NPs were induced, and prolonged release of the plasmid DNA was achieved compared to the chickens immunized with the control plasmid. This study lays the foundation for the further development of mucosal vaccines and drugs encapsulated in chitosan nanoparticles. PMID:24426783

Zhao, Kai; Zhang, Yang; Zhang, Xiaoyan; Li, Wei; Shi, Ci; Guo, Chen; Dai, Chunxiao; Chen, Qian; Jin, Zheng; Zhao, Yan; Cui, Hongyu; Wang, Yunfeng

2014-01-01

366

A preliminary ferritic-martensitic stainless steel constitution diagram  

SciTech Connect

This paper describes preliminary research to develop a constitution diagram that will more accurately predict the microstructure of ferritic and martensitic stainless steel weld deposits. A button melting technique was used to produce a wide range of compositions using mixtures of conventional ferritic and martensitic stainless steels, including types 403, 409, 410, 430, 439 and 444. These samples were prepared metallographically, and the vol-% ferrite and martensite was determined quantitatively. In addition, the hardness and ferrite number (FN) were measured. Using this data, a preliminary constitution diagram is proposed that provides a more accurate method for predicting the microstructures of arc welds in ferritic and martensitic stainless steels.

Balmforth, M.C.; Lippold, J.C. [Ohio State Univ., Columbus, OH (United States). Welding and Joining Metallurgy Group

1998-01-01

367

Characterization of iron hydroxide/oxide nanoparticles prepared in microemulsions stabilized with cationic/non-ionic surfactant mixtures.  

PubMed

Iron oxide-hydroxide (?-Fe(2)O(3); Fe(OH)(3)) nanoparticles have been prepared by a microemulsion route using ammonia (NH(3)) solution or tetrabutylammonium hydroxide (TBAH) as precipitants. The iron oxide-hydroxide nanoparticles obtained were characterized by TGA, N(2) sorptiometry, XRD, IR, SEM, HR-TEM, and DLS techniques. Properties such as specific surface area (S(BET)), pore sizes and shapes, average particle size and distribution, crystallite structure, and thermal stability were determined. The properties of nanoparticles prepared using NH(3) and TBAH were compared after drying at 100°C and after being calcined in the temperature range 250-1100°C. It was found that the suspensions prepared using TBAH suffered immediate separation while those prepared using NH(3) resulted in very stable suspensions. Also, it was found that TBAH did not offer any advantage over NH(3) either in terms of specific surface area or in particle size of the prepared nanoparticles. Hence, the later part of the study was concentrated on the NH(3)-precipitated nanoparticles with particular emphasis on finding the most favorable, W (water-to-surfactant ratio) and/or surfactant concentration, S, to obtain the best conditions in terms of higher surface areas and narrower particle size distribution. It was found that the prepared suspension consisted of monodisperse nanoparticles (standard deviations <10%) and after separation and drying, high surface area powders were obtained. The highest surface area (315 m(2) g(-1)) was obtained when the smallest W (=20) and highest S (=0.20 mol L(-1)) were employed. PMID:21232750

Bumajdad, Ali; Ali, Sami; Mathew, Asha

2011-03-15

368

Oral insulin delivery in rats by nanoparticles prepared with non-toxic solvents.  

PubMed

Nanoparticles (NPs) have shown a certain potential to overcome the drawbacks of oral peptide delivery in the gastrointestinal tract such as low peptide stability and permeability. The preparation of insulin loaded NPs was carried out with Eudragit RL or RS dissolved in different non-toxic polyethylene glycol (PEG) derivatives. The use of these non-toxic solvents allowed the design of an one step NP preparation method where insulin retained its full biological activity as it was proven in vitro and in vivo. The insulin trapping NPs were in a size range of around 150-250 nm and exhibited a pH-dependent release. The type of solvent did not distinctly influence the particle properties or insulin stability but modified significantly the performance in vivo in rats, NPs prepared with glycofurol led to a bioavailability of F=1.4 ± 1.0% after oral administration while NPs prepared with PEG 300 were hardly efficient (F=0.3 ± 0.5%). In all cases t(max) was shifted to 2h compared to 1h after subcutaneous insulin solution. In general, we believe that the method presented here is a promising way to encapsulate sensitive drugs, especially for the production of peptide loaded NPs. PMID:23328680

Viehof, Angela; Javot, Lucie; Béduneau, Arnaud; Pellequer, Yann; Lamprecht, Alf

2013-02-25

369

Preparation of europium-quantum dots and europium-fluorescein composite nanoparticles available for ratiometric luminescent detection of metal ions.  

PubMed

The silica-encapsulated luminescent lanthanide nanoparticles have been developed for the selective tagging of a wide range of important targets in recent years, however, they are mainly limited to europium and terbium compounds. In this work, two types of europium-containing dual-luminophore silica nanoparticles, silica-encapsulated CdTe quantum dots (CdTe QDs)-BHHCT-Eu(3+) complex nanoparticles and BHHCT-Eu(3+) surface-bound silica-encapsulated fluorescein isothiocyanate (FITC) nanoparticles (BHHCT: 4, 4'-bis(1'', 1'', 1'', 2'', 2'', 3'', 3''-heptafluoro-4'', 6''-hexanedion-6''-yl)chlorosulfo-o-terphenyl), were successfully prepared using a water-in-oil (W/O) reverse microemulsion method. The results of transmission electron microscopy and luminescence spectroscopy characterizations indicate that the two types of nanoparticles are all monodisperse, spherical and uniform in size (approximately 50 nm in diameter), and have well-resolved and stable dual luminescence emission properties. The CdTe QDs-BHHCT-Eu(3+) nanoparticles can be excited at 365 nm to give dual-emission peaks at 535 and 610 nm, and the FITC-BHHCT-Eu(3+) nanoparticles can be excited at 335 nm to give dual-emission peaks at 515 and 610 nm. The luminescence response investigations of the nanoparticles to different metal ions indicate that the new nanoparticles can be used as ratiometric luminescent sensing probes for the selective detection of Cu(2+) and Fe(2+) ions, respectively. The performance of the nanoparticle probe for metal ion detection was investigated. PMID:20820091

Dong, Haitao; Liu, Yan; Wang, Dandan; Zhang, Wenzhu; Ye, Zhiqiang; Wang, Guilan; Yuan, Jingli

2010-10-01

370

Methods of preparation and modification of advanced zero-valent iron nanoparticles, their properties and application in water treatment technologies  

NASA Astrophysics Data System (ADS)

Zero-valent iron nanoparticles are commonly used in modern water treatment technologies. Compared to conventionally-used macroscopic iron or iron microparticles, the using of nanoparticles has the advantages given mainly by their generally large specific surface area (it drives their high reactivity and/or sorption capacity), small dimensions (it allows their migration e.g. in ground water), and particular physical and chemical properties. Following the applications of zero-valent iron particles in various pilot tests, there arose several critical suggestions for improvements of used nanomaterials and for development of new generation of reactive nanomaterials. In the presentation, the methods of zero-valent iron nanoparticles synthesis will be summarized with a special attention paid to the thermally-induced solid-state reaction allowing preparation of zero-valent iron nanoparticles in an industrial scale. Moreover, the method of thermal reduction of iron-oxide precursors enables to finely tune the critical parameters (mainly particle size and morphology, specific surface area, surface chemistry of nanoparticles etc.) of resulting zero-valet iron nanoparticles. The most important trends of advanced nanoparticles development will be discussed: (i) surface modification of nanomaterilas, (ii) development of nanocomposites and (iii) development of materials for combined reductive-sorption technologies. Laboratory testing of zero-valent iron nanoparticles reactivity and migration will be presented and compared with the field observations: the advanced zero-valent iron nanoparticles were used for groundwater treatment at the locality contaminated by chlorinated hydrocarbons (VC, DCE, TCE and PCE) and reacted nanoparticles were extracted from the sediments for their fate assessment. The authors gratefully acknowledge the support by the Technology Agency of the Czech Republic "Competence Centres" (project No. TE01020218) and the EU FP7 (project NANOREM).

Filip, Jan; Kašlík, Josef; Med?ík, Ivo; Petala, Eleni; Zbo?il, Radek; Slunský, Jan; ?erník, Miroslav; Stav?lová, Monika

2014-05-01

371

Investigation of structural and magnetic properties of nanocrystalline manganese substituted lithium ferrites  

SciTech Connect

Nanocrystalline manganese substituted lithium ferrites Li{sub 0.5}Fe{sub 2.5-x}Mn{sub x}O{sub 4} (2.5<=x>=0) were prepared by sol-gel auto-combustion method. X-ray diffraction patterns revealed that as the concentration of manganese increased, the cubic phase changed to tetragonal. Magnetic properties were measured by hysteresis loop tracer technique. All the compositions indicated ferrimagnetic nature. The surface morphology of all the samples was studied by using scanning and transmission electron microscopy. The substitution of manganese ions in the lattice affected the structural as well as magnetic properties of spinels. - Graphical abstract: The synthesized nanoparticles shapes, sizes and size dispersibilities were obtained from the transmission electron microscopy (TEM). The TEM micrographs of synthesized samples revealed that, spherical shape with average particle size 50 nm. Selected area electron diffraction pattern (SAED) suggests the polycrystallinity and also the formation of spinel ferrites.

Hankare, P.P., E-mail: p_hankarep@rediffmail.co [Department of Chemistry, Shivaji University, Kolhapur 416004, Maharashtra (India); Patil, R.P., E-mail: raj_rbm_raj@yahoo.co.i [Department of Chemistry, Shivaji University, Kolhapur 416004, Maharashtra (India); Sankpal, U.B.; Jadhav, S.D. [Department of Chemistry, Shivaji University, Kolhapur 416004, Maharashtra (India); Lokhande, P.D. [Pune University, Pune, Maharashtra, India. (India); Jadhav, K.M. [Dr. B.A.Marathwada University, Aurangabad 431004, Maharashtra (India); Sasikala, R. [Chemistry Division, Bhabha Atomic Research Center, Mumbai 400085, Maharashtra (India)

2009-12-15

372

Preparation of Fe 3 O 4 \\/polystyrene composite particles from monolayer oleic acid modified Fe 3 O 4 nanoparticles via miniemulsion polymerization  

Microsoft Academic Search

Fe3O4\\/polystyrene composite particles were prepared from oleic acid (OA) modified Fe3O4 nanoparticles via miniemulsion polymerization. It was concluded that the surface properties of OA modified magnetite nanoparticles\\u000a have a great effect on preparation of the composite particles. When Fe3O4 nanoparticles coated by multilayer of OA was employed, there were large amounts of free polystyrene particles in the product.\\u000a Fe3O4\\/polystyrene composite

Feng Yan; Jun Li; Jianjun Zhang; Fengqi Liu; Wensheng Yang

2009-01-01

373

Preparation and Properties of Nanoparticles of Calcium Phosphates With Various Ca/P Ratios  

PubMed Central

This study aimed at preparing and studying the properties of nanoparticles of calcium phosphate (nCaP) with Ca/P ratios ranging from 1.0 to 1.67 using a spray-drying technique. Micro-structural analyses suggested that the nCaPs with Ca/P ratios of 1.67 to 1.33 were nano-sized amorphous calcium phosphate (ACP) containing varying amounts of acid phosphate and carbonate. The nCaP with Ca/P ratio of 1 contained only nano-sized low crystalline dicalcium phosphate (DCP). BET measurements of the nCaPs showed specific surface areas of (12 ± 2 to 50 ± 1) m2/g, corresponding to estimated equivalent spherical diameters of (38 to 172) nm. However, dynamic light scattering measurements revealed much larger particles of (380 ± 49 to 768 ± 111) nm, owing to agglomeration of the smaller primary nano particles as revealed by Scanning Electron Microscopy (SEM). Thermodynamic solubility measurements showed that the nCaPs with Ca/P ratio of 1.33 – 1.67 all have similar solubility behavior. The materials were more soluble than the crystalline hydroxyapatite (HA) at pH greater than about 4.7, and more soluble than ?-tricalcium phosphate (?-TCP), octacalcium phosphate (OCP) and DCP at pH above 5.5. Their solubility approached that of ?-tricalcium phosphate (?-TCP) at about pH 7. These nCaPs, which cannot be readily prepared by other currently available methods for nanoparticle preparation, have potential biomedical applications. PMID:21037948

Sun, Limin; Chow, Laurence C.; Frukhtbeyn, Stanislav A.; Bonevich, John E.

2010-01-01

374

Preparation and photocatalytic activity of eccentric Au-titania core-shell nanoparticles by block copolymer templates.  

PubMed

A novel route for a preparation of eccentric Au-titania core-shell nanoparticles using gold nanoparticles (AuNPs) with block copolymer shells as a template is reported. AuNPs with poly(2-vinyl pyridine)-block-poly(ethylene oxide) (PVP-b-PEO) block copolymer shells are first prepared by UV irradiation of the solution of PVP-b-PEO/HAuCl(4) complexes. Then the sol-gel reaction of titanium tetra-isopropoxide (TTIP) selectively on the surfaces of AuNPs leads to Au-titania core-shell composite nanoparticles. The eccentric Au-titania core-shell nanoparticles are obtained from the Au-titania core-shell composite nanoparticles by removal of organic interlayer by UV treatment. Photocatalytic activities of the resulting eccentric core-shell nanoparticles are investigated in terms of the degradation of methylene blue (MB). The results show that the eccentric core-shell structures endow the catalyst with greatly enhanced photocatalytic activity. PMID:21157597

Li, Xue; Fu, Xiaoning; Yang, Hui

2011-02-21

375

Thermal plasma synthesis of nanocrystalline ferrite particles  

NASA Astrophysics Data System (ADS)

Highly functional soft magnetic materials have received a dramatically growing interest in the last two decades, along with amazing technological advances in electronics and telecommunications. Among soft magnetic materials ferrites are important and promising candidates for use at high frequencies because of their high resistivities. There has been another important development towards better soft magnetic materials, which is nanostructured materials technology. As a result of an ultrafine grain size and consequent large volume fraction of atoms occupying the interfacial regions, nanocrystalline materials show interesting properties that are often different from those of conventional bulk materials. Nanocrystalline ferrite materials are novel candidates for high-frequency soft magnetic applications because of their higher resistivities than metallic counterparts and of grain size dependent magnetic properties. For the first time, RF plasma torch synthesis of a series of ferrite nanoparticles using metallic precursor powders was carried out in this study. Microstructural and magnetic properties of the as-synthesized powders were examined. The viability of plasma torch synthesis for production of ferrite nanoparticles has been demonstrated over the results. Magnetite, Ni-, NiZn-, Mn-, and MnZn-ferrite have been successfully synthesized. The only oxygen source for oxide formation is the compressed air flowing through the reactor. The average grain sizes of the plasma-torched powders are in the range of 10--30 nm, with a standard deviation of ˜10 nm. Their stoichiometries are slightly off from the desired ones. These ferrite nanoparticles had well-defined polygonal growth shapes showing (100) and (111) faceting. Most of them are truncated octahedral or truncated cubic shapes. Some theoretical calculations based on the cuboctahedron model revealed that the surface energy ratio of (100) to (111) planes, gamma100/gamma111, must have a value between 0.577 and 1.732 under the assumption of the same edge length. EXAFS analysis was helpful to determine the interstitial site occupation by the metallic cations in the ferrites and to reveal that there is a surface truncation of the lattice. Mossbauer analysis of the ferrite nanoparticles showed that Zn addition to the ferrite structure decreases the hyperfine magnetic fields of both sublattices and increases in the fraction of superparamagnetic particles.

Son, Suk-Joon

376

Preparation and characterization of radioactive dirhenium decacarbonyl-loaded PLLA nanoparticles for radionuclide intra-tumoral therapy.  

PubMed

This study describes the development of biocompatible radioactive rhenium-loaded nanoparticles for radionuclide anti-cancer therapy. To achieve this goal, dirhenium decacarbonyl [Re2(CO)10] has been encapsulated in poly(L-lactide) based nanoparticles by an oil-in-water emulsion-solvent evaporation method. A 3(3) factorial design method was applied to investigate the influence of both the proceeding and formulation parameters including the stirring speed and the concentration of both the PLLA polymer and the poly(vinyl alcohol) stabiliser on both nanoparticles size and the Re2(CO)10 encapsulation efficacy. The factorial design results attributed a clear negative effect for the stirring speed and the stabiliser concentration on the nanoparticles size while the polymer concentration exhibited a positive one. Regarding the Re2(CO)10 encapsulation efficacy, higher values were obtained when higher polymer concentrations, lower stabiliser concentrations or slower stirring speeds were applied in the preparation. Different tests were thereafter performed to characterize the Re2(CO)10-loaded nanoparticles. The nanoparticles size, being experimentally controlled by the above mentioned parameters, ranged between 330 and 1500 nm and the maximum rhenium loading was 24% by nanoparticles weight as determined by atomic emission assays and neutron activation analysis. Furthermore, the rhenium distribution within nanoparticles has been shown to be homogeneous as confirmed by the energy dispersive X-ray spectrometry. DSC assays demonstrated that Re2(CO)10 was encapsulated in its crystalline initial state. Other experiments including FT-IR and NMR did not show interactions between PLLA and Re2(CO)10. To render them radioactive, these nanoparticles have been bombarded with a neutron flux of 1.45x10(13) n/cm2/s during 1 h. The SEM micrographs of nanoparticles after neutron bombardment showed that the nanoparticles remained spherical and separated but slightly misshaped. These applied neutron activation conditions yielded a specific activity of about 32.5 GBq per gram of nanoparticles. Preliminary estimations allow us to think that a sole injection of 50 mg of these activated nanoparticles into a brain tumor model (4.2 cm diameter) would deliver a tumor absorbed dose of up to 47 Gy. In conclusion, these dirhenium decacarbonyl-loaded nanoparticles represent a novel promising tool for radionuclide anti-cancer therapy. PMID:17521895

Hamoudeh, Misara; Salim, Hani; Barbos, Dumitru; Paunoiu, Coustantin; Fessi, Hatem

2007-11-01

377

Bi-nanoparticle (CdTe and CdSe) mixed polyaniline hybrid thin films prepared using spin coating technique  

NASA Astrophysics Data System (ADS)

Polyaniline (Pani) films containing CdTe, CdSe, and both nanoparticles were deposited using spin coating technique. Pani was chemically synthesized by oxidation method, whereas surfactant free CdTe and CdSe nanoparticles were prepared using solvothermal method. Binanoparticle films showed an increase in the absorption from 350 nm to the near IR region. Absorption spectra also showed charge transfer complex formation for the binanoparticle hybrid thin films prepared with weight ratio of [Pani (camphor sulfonic acid, CSA):CdTe:CdSe] 200:100:75. Photoluminescence measurement for the bi-nanoparticle hybrid thin films confirmed that the required dissociation of excitons was taking place at the interface. Scanning electron microscopy images showed homogeneity and an interconnected network on the surface of the films prepared with Pani (CSA):CdTe:CdSe weight ratios of 200:100:50 and 200:100:75, respectively. Cyclic voltammetry confirmed better stability for the bi-nanoparticle hybrid films in comparison to Pani film. It also established the process of electrochemical charge transfer between the nanoparticles and the polymer matrix.

Verma, Deepak; Dutta, V.

2009-02-01

378

Structural, optical and magnetic properties of Co-doped ZnO nanoparticles prepared via a wet chemical route  

NASA Astrophysics Data System (ADS)

In this paper, ZnO nanoparticles doped with varying amount of Co content (i.e., 0, 2, 4, 6, 8, and 10 at.%) have been prepared by wet chemical route. X-ray diffraction (XRD) results reveal the successful substitution of Co2+ ions on to sites of Zn2+ ions without forming any secondary phase. Furthermore, a linear increase in d-spacing of the ZnO lattice is found with the increase in Co content. SEM images demonstrate the formation of homogeneously distributed spherical nanoparticles with average size of 50-70 nm. It is observed from optical investigations that band gap energy of ZnO nanoparticles significantly decreased with the increase in Co doping level. Interestingly, it is found that the high Co dopant concentration can lead to room temperature ferromagnetism in ZnO nanoparticles.

Iqbal, Javed; Janjua, Raheel Ahmed; Jan, Tariq

2014-07-01

379

Flash microwave synthesis of trevorite nanoparticles  

SciTech Connect

Nickel ferrite nanoparticles have several possible applications as cathode materials for rechargeable batteries, named 'lithium-ion' batteries. In this study, NiFe{sub 2}O{sub 4} was prepared by microwave induced thermohydrolysis. The obtained nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), BET method, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). All the results show that the microwave one-step flash synthesis leads in a very short time to NiFe{sub 2}O{sub 4} nanoparticles with elementary particles size close to 4-5 nm, and high specific surfaces (close to 240 m{sup 2}/g). Thus, microwave heating appears as an efficient source of energy to produce quickly nanoparticles with complex composition as ferrite. - Graphical abstract: At the end of the 20th century, a new concept of battery was introduced, named 'Li ion', where electrodes are both lithium-storage materials. Compounds with a spinel structure are so investigated and microwave heating appears as an efficient source of energy to produce nanoparticles in a very short time and at low temperature, with controlled size (4-5 nm) and high specific area (240 m{sup 2}/g). Legend: Pictogram represents our original microwave reactor, the RAMO (French acronym of Reacteur Autoclave Micro-Onde), containing the reactants and submitted to the microwave irradiation. Multicolor candy represents obtained material.

Bousquet-Berthelin, C. [NANOSCIENCES-GERM - Groupe d'Etudes et de Recherches en Microondes, I.C.B. (Institut Carnot de Bourgogne), UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, B.P. 47870, 21078 Dijon Cedex (France)], E-mail: christelle.bousquet@u-bourgogne.fr; Chaumont, D.; Stuerga, D. [NANOSCIENCES-GERM - Groupe d'Etudes et de Recherches en Microondes, I.C.B. (Institut Carnot de Bourgogne), UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, B.P. 47870, 21078 Dijon Cedex (France)

2008-03-15

380

Preparation of monodispersed cobalt-boron spherical nanoparticles and their behavior during the catalytic decomposition of hydrous hydrazine  

SciTech Connect

Monodispersed cobalt-boron spherical nanoparticles have been prepared through solution plasma processing in the presence of hexadecyltrimethyl ammonium bromide for the first time. The particle size of cobalt-boron can be adjusted by changing either the plasma time or the concentration of hexadecyltrimethyl ammonium bromide. The samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. During the decomposition of hydrous hydrazine, the obtained monodispersed cobalt-boron spherical nanoparticles exhibit higher catalytic activity and hydrogen selectivity than regular cobalt-boron prepared by direct reduction of Co{sup 2+} with BH{sub 4}{sup -}. The experimental investigations indicate that hydrous hydrazine along with the monodispersed cobalt-boron spherical nanoparticles may find application in small-scale on-board hydrogen storage and supply.

Tong, D.G., E-mail: tongdongge@163.com [College of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China); Zeng, X.L. [College of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China)] [College of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China); Chu, W., E-mail: chuwei65@yahoo.com.cn [Lab 230, College of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Wang, D.; Wu, P. [College of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China)] [College of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China)

2010-04-15

381

Enhanced oral bioavailability of docetaxel by lecithin nanoparticles: preparation, in vitro, and in vivo evaluation  

PubMed Central

The aim of this research work was to investigate the potential of lecithin nanoparticles (LNs) in improving the oral bioavailability of docetaxel. Docetaxel-loaded LNs (DTX-LNs) were prepared from oil-in-water emulsions and characterized in terms of morphology, size, zeta potential, and encapsulation efficiency. The in vitro release of docetaxel from the nanoparticles was studied by using dialysis bag method. Caco-2 cell monolayer was used for the in vitro permeation study of DTX-LNs. Bioavailability studies were conducted in rats and different pharmacokinetic parameters were evaluated after oral administration of DTX-LNs. The results showed that DTX-LNs had a mean diameter of 360 ± 8 nm and exhibited spherical shape with smooth surface under transmission electron microscopy. The DTX-LNs showed a sustained-release profile, with about 80% of docetaxel released within 72 hours. The apical to basolateral transport of docetaxel across the Caco-2 cell monolayer from the DTX-LNs was 2.14 times compared to that of the docetaxel solution (0.15 × 10?5 ± 0.016 × 10?5 cm/second versus 0.07 × 10?5 ± 0.003 × 10?5 cm/second). The oral bioavailability of the DTX-LNs was 3.65 times that of docetaxel solution (8.75% versus 2.40%). These results indicate that DTX-LNs were valuable as an oral drug delivery system to enhance the absorption of docetaxel. PMID:22848177

Hu, Kaili; Cao, Shan; Hu, Fuqiang; Feng, Jianfang

2012-01-01

382

Characterization and antimicrobial activity of silver nanoparticles prepared by a thermal decomposition technique  

NASA Astrophysics Data System (ADS)

Recently, there has been an increasing need of efficient synthetic protocols using eco-friendly conditions including low costs and green chemicals for production of metal nanoparticles. In this work, silver nanoparticles (silver NPs) with average particle size about 10 nm were synthesized by using a thermal decomposition technique. Unlike the colloidal chemistry method, the thermal decomposition method developed has advantages such as the high crystallinity, single-reaction synthesis, and easy dispersion ability of the synthesized NPs in organic solvents. In a modified synthesis process, we used sodium oleate as a capping agent to modify the surface of silver NPs because the oleate has a C18 tail with a double bond in the middle, therefore, forming a kink which is to be effective for aggregative stability. Importantly, the as-synthesized silver NPs have demonstrated strong antimicrobial effects against various bacteria and fungi strains. Electron microscopic studies reveal physical insights into the interaction and bactericidal mechanism between the prepared silver NPs and tested bacteria in question. The observed excellent antibacterial and antifungal activity of the silver NPs make them ideal for disinfection and biomedicine applications.

Tam, Le Thi; Phan, Vu Ngoc; Lan, Hoang; Thuy, Nguyen Thanh; Hien, Tran Minh; Huy, Tran Quang; Quy, Nguyen Van; Chinh, Huynh Dang; Tung, Le Minh; Tuan, Pham Anh; Lam, Vu Dinh; Le, Anh-Tuan

2013-11-01

383

Preparation of amorphous aluminum oxide-hydroxide nanoparticles in amphiphilic silicone-based copolymer microemulsions.  

PubMed

Organo-inorgano nanocomposites with colloidal dimensions have interesting optical, catalytic, and mechanical properties, particularly when such hybrids are reinforced with transition metal oxide nanoparticles. Nanoparticles with a mean size of 1.0-2.4 nm are obtained through hydrolysis of aluminum isopropoxide in the L(2) phase of amphiphilic (PDMS-POE) polydimethylsiloxane-polyoxyethylene Silwet L-7607-octanol/acetylacetone-water mixtures. The particle sizes are related weakly to the microemulsion composition: 0.8-1.2 nm for 20 wt% Silwet L-7607 and 2.0-2.4 nm for 50 wt% Silwet L-7607. Protection of the particles against aggregation is ensured through their confinement in the intraaggregate colloidal domains. Factors affecting the hydrolysis-condensation process of acetylacetone-complexed aluminum isopropoxide in copolymer-poor and copolymer-rich regions of PDMS-POE W/O microemulsions are studied by Fourier transform infrared spectroscopy, small angle X-ray scattering, and transmission electron microscopy. Prepared nanoparticulate dispersions possess long-term stability and form clear mixtures in different organic polar and nonpolar solvents. PMID:16290335

Berkovich, Yana; Aserin, Abraham; Wachtel, Ellen; Garti, Nissim

2002-01-01

384

Preparation and Characterization of Tripterygium wilfordii Multi-Glycoside Nanoparticle Using Supercritical Anti-Solvent Process  

PubMed Central

The aim of this study was to prepare nanosized Tripterygium wilfordii multi-glycoside (GTW) powders by the supercritical antisolvent precipitation process (SAS), and to evaluate the anti-inflammatory effects. Ethanol was used as solvent and carbon dioxide was used as an antisolvent. The effects of process parameters such as precipitation pressure (15–35 MPa), precipitation temperature (45–65 °C), drug solution flow rates (3–7 mL/min) and drug concentrations (10–30 mg/mL) were investigated. The nanospheres obtained with mean diameters ranged from 77.5 to 131.8 nm. The processed and unprocessed GTW were characterized by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and thermal gravimetric analysis. The present study was designed to investigate the beneficial effect of the GTW nanoparticles on adjuvant-induced arthritis in albino rats. The processed and unprocessed GTW were tested against Freund’s complete adjuvant-induced arthritis in rats. Blood samples were collected for the estimation of interleukins (IL-1?, IL-1?) and tumor necrosis factor-? (TNF-?). It was concluded that physicochemical properties and anti-inflammatory activity of GTW nanoparticles could be improved by physical modification, such as particle size reduction using supercritical antisolvent (SAS) process. Further, SAS process was a powerful methodology for improving the physicochemical properties and anti-inflammatory activity of GTW. PMID:24549173

Chen, Fengli; Li, Tong; Li, Shuangyang; Hou, Kexin; Liu, Zaizhi; Li, Lili; Cui, Guoqiang; Zu, Yuangang; Yang, Lei

2014-01-01

385

Preparation of ruby red glasses from gold nanoparticles: Influence of stannic oxide  

NASA Astrophysics Data System (ADS)

In this work, effects of stannic oxide concentration to red glass prepared from gold nanoparticle (AuNPs) have been investigated. The glasses were fabricated by conventional melt quench method using SiO2, CaO, K2CO3, Na2CO3, SeO2, AuNPs and vary stannic oxide concentration by 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5 % by weight. The result found that, the red colors of glasses were obtained from gold nanoparticles at 0.1, 0.2 and 0.5 % of stannic oxide. At 0.0, 0.3 and 0.4 % are show purple-blue colors. The results reflecting that the particle size of gold particle in glass matrices at 0.1, 0.2 and 0.5 % of stannic oxide are smaller than 0.3 and 0.4 %. The color of glasses were confirmed by uv-visible spectrophotometer and color coordinate in CIEL*a*b*.

Ruangtaweep, Y.; A-nupan, P.; Kaewkhao, J.

2014-03-01

386

Facile preparation of paclitaxel loaded silk fibroin nanoparticles for enhanced antitumor efficacy by locoregional drug delivery.  

PubMed

Non-toxic, safe materials and preparation methods are among the most important factors when designing nanoparticles (NPs) for future clinical application. Here we report a novel and facile method encapsulating anticancer drug paclitaxel (PTX) into silk fibroin (SF), a biocompatible and biodegradable natural polymer, without adding any toxic organic solvents, surfactants or other toxic agents. The paclitaxel loaded silk fibroin nanoparticles (PTX-SF-NPs) with a diameter of 130 nm were formed in an aqueous solution at room temperature by self-assembling of SF protein, which demonstrated mainly silk I conformation in the NPs. In cellular uptake experiments, coumarin-6 loaded SF NPs were taken up efficiently by two human gastric cancer cell lines BGC-823 and SGC-7901. In vitro cytotoxicity studies demonstrated that PTX kept its pharmacological activity when incorporating into PTX-SF-NPs, while SF showed no cytotoxicity to cells. The in vivo antitumor effects of PTX-SF-NPs were evaluated on gastric cancer nude mice exnograft model. We found that locoregional delivery of PTX-SF-NPs demonstrated superior antitumor efficacy by delaying tumor growth and reducing tumor weights compared with systemic administration. Furthermore, the organs of mice in NP treated groups didn't show obvious toxicity, indicating the in vivo safety of SF NPs. These results suggest that SF NPs are promising drug delivery carriers, and locoregional delivery of SF NPs could be a potential future clinical cancer treatment regimen. PMID:24274601

Wu, Puyuan; Liu, Qin; Li, Rutian; Wang, Jing; Zhen, Xu; Yue, Guofeng; Wang, Huiyu; Cui, Fangbo; Wu, Fenglei; Yang, Mi; Qian, Xiaoping; Yu, Lixia; Jiang, Xiqun; Liu, Baorui

2013-12-11

387

Preparation of airborne Ag/CNT hybrid nanoparticles using an aerosol process and their application to antimicrobial air filtration.  

PubMed

Carbon nanotubes (CNTs) have been widely used in a variety of applications because of their unique structure and excellent mechanical and electrical properties. Additionally, silver (Ag) nanoparticles exhibit broad-spectrum biocidal activity toward many different bacteria, fungi, and viruses. In this study, we prepared Ag-coated CNT hybrid nanoparticles (Ag/CNTs) using aerosol nebulization and thermal evaporation/condensation processes and tested their usefulness for antimicrobial air filtration. Droplets were generated from a CNT suspension using a six-jet collison nebulizer, passed through a diffusion dryer to remove moisture, and entered a thermal tube furnace where silver nanoparticles were generated by thermal evaporation/condensation at ?980 °C in a nitrogen atmosphere. The CNT and Ag nanoparticle aerosols mixed together and attached to each other, forming Ag/CNTs. For physicochemical characterization, the Ag/CNTs were introduced into a scanning mobility particle sizer (SMPS) for size distribution measurements and were sampled by the nanoparticle sampler for morphological and elemental analyses. For antimicrobial air filtration applications, the airborne Ag/CNT particles generated were deposited continuously onto an air filter medium. Physical characteristics (fiber morphology, pressure drop, and filtration efficiency) and biological characteristics (antimicrobial tests against Staphylococcus epidermidis and Escherichia coli bioaerosols) were evaluated. Real-time SMPS and transmission electron microscopy (TEM) data showed that Ag nanoparticles that were <20 nm in diameter were homogeneously dispersed and adhered strongly to the CNT surfaces. Because of the attachment of Ag nanoparticles onto the CNT surfaces, the total particle surface area concentration measured by a nanoparticle surface area monitor (NSAM) was lower than the summation of each Ag nanoparticle and CNT generated. When Ag/CNTs were deposited on the surface of an air filter medium, the antimicrobial activity against test bacterial bioaerosols was enhanced, compared with the deposition of CNTs or Ag nanoparticles alone, whereas the filter pressure drop and bioaerosol filtration efficiency were similar to those of CNT deposition only. At a residence time of 2 h, the relative microbial viabilities of gram-positive S. epidermidis were ?32, 13, 5, and 0.9% on the control, CNT-, Ag nanoparticle-, and Ag/CNT-deposited filters, respectively, and those of gram-negative E. coli were 13, 2.1, 0.4, and 0.1% on the control, CNTs, Ag nanoparticles, and Ag/CNTs, respectively. These Ag/CNT hybrid nanoparticles may be useful for applications in biomedical devices and antibacterial control systems. PMID:21751779

Jung, Jae Hee; Hwang, Gi Byoung; Lee, Jung Eun; Bae, Gwi Nam

2011-08-16

388

Physical properties of nanoparticle silica gel doped with CdS prepared by sol-gel technique  

Microsoft Academic Search

CdS\\/silica xerogel glasses were prepared via silica gels containing mixture solution of 0.2 M (CdCl2 and thiourea) with molar ratio 1:1. Doping the gels with this mixture solution and its heat treatment gave transparent yellow silica-gel glasses doped with CdS crystals. X-ray diffraction and transmission electron microscope make it possible to evaluate the nanoparticle size of the prepared samples. The

I. K. Battisha

2002-01-01

389

Improvement of mechanical durability on organic TFT with printed electrodes prepared from nanoparticle ink  

NASA Astrophysics Data System (ADS)

We investigated a mechanism of improving adhesiveness depending on sintering temperature for printed silver (Ag) electrodes prepared from nanoparticle ink on an insulating polymer layer as the under layer. The adhesion strength significantly improved by sintering the Ag electrodes at a temperature above the glass transition temperature (Tg) of the polymer layer. In the sample with improved adhesiveness, the interfacial fusion between the printed Ag electrodes and polymer layer was observed in a cross sectional scanning electron microscope image. Based on this mechanism, we have successfully demonstrated the improvement in mechanical durability of organic thin-film transistors (TFTs) with printed Ag electrodes. The degradation of the organic TFTs after applying bending stress was significantly suppressed by interfacial fusion.

Sekine, Tomohito; Ikeda, Hideaki; Kosakai, Akifumi; Fukuda, Kenjiro; Kumaki, Daisuke; Tokito, Shizuo

2014-03-01

390

Sonochemically synthesis of pyrazolones using reusable catalyst CuI nanoparticles that was prepared by sonication.  

PubMed

A simple and green process to prepare copper iodide in nano scale via sonication was carried out. Subsequently, this nanoparticles was used as an efficient catalyst for the synthesis of 2-aryl-5-methyl-2,3-dihydro-1H-3-pyrazolones via four-component reaction of hydrazine, ethyl acetoacetate, aldehyde and ?-naphthol in water under ultrasound irradiation. The combinatorial synthesis was attained for this procedure with applying ultrasound irradiation while making use of water as green ambient. Simple work-up, excellent yield of products and short reaction times are some of the important features of this protocol. Notably, this catalyst could be recycled and reused for five times without noticeably decreasing the catalytic activity. PMID:23414833

Ziarati, Abolfazl; Safaei-Ghomi, Javad; Rohani, Sahar

2013-07-01

391

Stable oligomeric clusters of gold nanoparticles: preparation, size distribution, derivatization, and physical and biological properties.  

PubMed

Reducing dilute aqueous HAuCl4 with NaSCN under alkaline conditions produces 2-3 nm diameter yellow nanoparticles without the addition of extraneous capping agents. We here describe two very simple methods for producing highly stable oligomeric grape-like clusters (oligoclusters) of these small nanoparticles. The oligoclusters have well-controlled diameters ranging from ?5 to ?30 nm, depending mainly on the number of subunits in the cluster. Our first ["delay-time"] method controls the size of the oligoclusters by varying from seconds to hours the delay time between making the HAuCl4 alkaline and adding the reducing agent, NaSCN. Our second ["add-on"] method controls size by using yellow nanoparticles as seeds onto which varying amounts of gold derived from "hydroxylated gold", Na(+)[Au(OH4-x)Clx](-), are added-on catalytically in the presence of NaSCN. Possible reaction mechanisms and a simple kinetic model fitting the data are discussed. The crude oligocluster preparations have narrow size distributions, and for most purposes do not require fractionation. The oligoclusters do not aggregate after ?300-fold centrifugal-filter concentration, and at this high concentration are easily derivatized with a variety of thiol-containing reagents. This allows rare or expensive derivatizing reagents to be used economically. Unlike conventional glutathione-capped nanoparticles of comparable gold content, large oligoclusters derivatized with glutathione do not aggregate at high concentrations in phosphate-buffered saline (PBS) or in the circulation when injected into mice. Mice receiving them intravenously show no visible signs of distress. Their sizes can be made small enough to allow their excretion in the urine or large enough to prevent them from crossing capillary basement membranes. They are directly visible in electron micrographs without enhancement, and can model the biological fate of protein-like macromolecules with controlled sizes and charges. The ease of derivatizing the oligoclusters makes them potentially useful for presenting pharmacological agents to different tissues while controlling escape of the reagents from the circulation. PMID:25317930

Smithies, Oliver; Lawrence, Marlon; Testen, Anze; Horne, Lloyd P; Wilder, Jennifer; Altenburg, Michael; Bleasdale, Ben; Maeda, Nobuyo; Koklic, Tilen

2014-11-11

392

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

SciTech Connect

Highlights: ? Amine-functionalized zinc oxide nanoparticle (AFZON) was synthesized. ? Isotherm and kinetics data followed Langmuir isotherm and pseudo-second order kinetic model, respectively. ? Q{sub 0} of ZON for AB25, DR23 and DR31 was 20, 12 and 15 mg/g, respectively. ? Q{sub 0} of AFZON for AB25, DR23 and DR31 was 1250, 1000 and 1429 mg/g, respectively. ? AFZON was regenerated at pH 12. -- Abstract: 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 (Q{sub 0}) 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.

Mahmoodi, Niyaz Mohammad, E-mail: nm_mahmoodi@yahoo.com [Department of Environmental Research, Institute for Color Science and Technology, Tehran (Iran, Islamic Republic of); Najafi, Farhood [Department of Resin and Additives, Institute for Color Science and Technology, Tehran (Iran, Islamic Republic of)] [Department of Resin and Additives, Institute for Color Science and Technology, Tehran (Iran, Islamic Republic of)

2012-07-15

393

A study of the frequency dependent susceptibility of a colloidal suspension of manganese ferrite (MnFe_20_4) nanoparticles  

Microsoft Academic Search

Measurements of the complex, frequency dependent susceptibility, chi (omega) = chi^{prime} (omega) - i chi^{prime prime} (omega) over the frequency range 50 MHz to 15 GHz, of a surfacted ferrofluid comprising MnFe204 ferrite particles in dibutylphthalat (DBP), as a function of a biasing magnetic field are presented. The biasing field was varied over the range 0 to 100 kAm^{-1}, and

P. C. Fannin; D. Vincent; G. Massart; P. Perov; S. Neveu

1999-01-01

394

The effect of polyvinyl alcohol (PVA) coating on structural, magnetic properties and spin dynamics of Ni0.3Zn0.7Fe2O4 ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

In this study, the structural and magnetic properties of uncoated and polyvinyl alcohol (PVA) coated Ni0.3Zn0.7Fe2O4 ferrite nanoparticles were studied using powder X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscope (TEM), Fourier Transform Infrared spectroscopy (FTIR) and magnetic measurements. The XRD patterns indicate that the crystalline structure is single phase cubic spinel and the spinel structure is retained after PVA coating. Also, after PVA coating, the crystallite size (from Scherrer formula) increases from 17 to 24 nm. The dc magnetization measurements revealed that both samples exhibit no hysteretic behavior at room temperature, symptomatic of the superparamagnetic behavior. The estimated values of z?, ?0 and T0, using the critical slowing down model, confirm the observed variation of freezing temperatures. AC susceptibility measurements showed the magnetic responses are frequency dependent, as an applicable potential in cancer therapy. The relative sensitivity of samples to the variation of applied frequency, as an important parameter in hyperthermia based therapy, increases by coating Ni0.3Zn0.7Fe2O4 nanoparticles with PVA.

Rahimi, M.; Kameli, P.; Ranjbar, M.; Salamati, H.

2013-12-01

395

In situ ultraviolet–visible absorbance measurement during and after solution plasma sputtering for preparation of colloidal gold nanoparticles  

NASA Astrophysics Data System (ADS)

The absorption spectra of the HCl, NaCl, and NaOH solutions during and after the solution plasma sputtering for the preparation of gold nanoparticles are measured by in situ ultraviolet–visible (UV–vis) spectroscopy to determine the particle diameter and behavior. In the solution plasma sputtering, gold particles are directly formed from the plasma phase and not by the reduction of Au3+ ions dissolved from electrodes. The initial diameter and behavior differ according to the solution used. In HCl solution, gold nanoparticles are formed and dissolve into Au3+ ions. When the solution is saturated, the gold nanoparticles grow by the aggregation of Au3+ ions. Cluster-sized particles are formed in NaCl solution that constitute nanoparticles, which are very stable for several days. Gold nanoparticles of 3 nm diameter are formed in NaOH solution, which aggregate over several days. The contribution of chlorine ions to the day-order stability of gold nanoparticles is suggested.

Mizutani, Tsuyoshi; Murai, Takaaki; Nameki, Hirofumi; Yoshida, Tomoko; Yagi, Shinya

2014-11-01

396

Development of poly(anhydride) nanoparticles loaded with peanut proteins: the influence of preparation method on the immunogenic properties.  

PubMed

Allergen-specific immunotherapy is based on the administration of allergens with the main disadvantage of inducing an allergic reaction. Within this context, we report the generation of an adjuvant and allergen-delivery system for peanut allergen immunotherapy with reduced IgE induction. Therefore, we prepared and characterized poly(anhydride) nanoparticles loaded with peanut proteins using the solvent displacement method, with some modifications in the manufacturing process. The precipitation of polymer was performed with either a mixture of ethanol and water or water. The resultant nanoparticles were dried by either freeze-drying or spray-drying, respectively. Poly(anhydride) nanoparticles loaded with peanut proteins were successfully developed, achieving both high encapsulation efficiency (70-80%) and manufacturing yield (60-80%). After intradermal immunization of mice (C57Bl/6) with peanut proteins incorporated into poly(anhydride) nanoparticles, a strong mixed T(H)1/T(H)2-type immune response was observed. Furthermore, we also provide, to our knowledge for the first time, clear evidence of the influence of formulation design on the immunostimulatory properties of nanoparticles. Taken together, our findings indicate that poly(anhydride) nanoparticles are efficient stimulators of immune responses and promising adjuvants and allergen-delivery systems applied for immunotherapy. PMID:22782031

Rebouças, Juliana De Souza; Irache, Juan Manuel; Camacho, Ana I; Esparza, Irene; Del Pozo, Victoria; Sanz, María L; Ferrer, Marta; Gamazo, Carlos

2012-10-01

397

Preparation and tribological properties of fluorosilane surface-modified lanthanum trifluoride nanoparticles as additive of fluoro silicone oil  

NASA Astrophysics Data System (ADS)

LaF3 nanoparticles surface-modified with fluorosilane were synthesized by surface modification technology. The size, morphology and phase structure of as-prepared surface-modified LaF3 nanoparticles were analyzed by means of X-ray diffraction and transmission electron microscopy. The tribological properties of surface-modified LaF3 nanoparticles as additive of fluoro silicone oil were evaluated with a four-ball machine, and the morphology and elemental composition of worn steel surfaces were examined with a scanning electron microscope and an X-ray photoelectron spectroscope. Results show that 3-(heptafluoroisopropoxy)propyltriethoxysilane as the modifier is able to improve the dispersibility of LaF3 nanoparticles in fluoro silicone oil. Moreover, when the optimum concentration, 0.08 wt.% of fluorosilane surface-modified LaF3 is added into fluoro silicone oil, as-synthesized fluorosilane surface-modified LaF3 nanoparticles exhibit excellent anti-wear as additive in fluoro silicone oil. The wear scar diameter under the optimum concentration is always smaller than that under the lubrication of fluoro silicone oil alone. Especially, when the load is 500 N, 600 N and 700 N, the wear scar diameter is reduced by 17%, 43% and 42%, respectively. In addition, during the friction process, LaF3 nanoparticles are deposited on the rubbed steel surface to form LaF3 deposition layer which functions jointly with the boundary lubricating film thereby resulting in improved tribological properties.

Hou, Xiao; He, Jie; Yu, Laigui; Li, Zhiwei; Zhang, Zhijun; Zhang, Pingyu

2014-10-01

398

Preparation and in vitro/in vivo characterization of enteric-coated nanoparticles loaded with the antihypertensive peptide VLPVPR  

PubMed Central

Our previous study revealed that the peptide Val-Leu-Pro-Val-Pro-Arg (VLPVPR), which was prepared using deoxyribonucleic acid recombinant technology, effectively decreased the blood pressure of spontaneous hypertensive rats; however, the effect only lasts 6 hours, likely due to its low absorption in the gastrointestinal tract. To overcome this problem, the purpose of this study was to characterize (methoxy-polyethylene glycol)-b-poly(D,L-lactide-co-glycolide)-b-poly(L-lysine) nanoparticles as in vitro and in vivo carriers for the effective delivery of VLPVPR. In our study, the VLPVPR nanoparticles were prepared using a double emulsion method, coated with Eudragit S100, and freeze-dried to produce enteric-coated nanoparticles. The optimized parameters from the double emulsion method was obtained from orthogonal experiments, including drug loading (DL) and encapsulated ratio (ER) at 6.12% and 86.94%, respectively, and the average particle size was below 100 nm. The release experiment demonstrated that the nanoparticles were sensitive to pH: almost completely released at pH 7.4 after 8 hours, but demonstrated much less release at pH 4.5 or pH 1.0 in the same amount of time. Therefore, the nanoparticles are suitable for enteric release. In vivo compared with the untreated group, the medium and high doses of orally administered VLPVPR nanoparticles reduced blood pressure for more than 30 hours, demonstrating that these nanoparticles have long-lasting and significant antihypertensive effects in spontaneously hypertensive rats. PMID:24729706

Sun, Haiyan; Liu, Dong; Li, Yan; Tang, Xuwei; Cong, Yanli

2014-01-01

399

Preparation and investigation of high solid content PTX-loaded nanoparticles dispersion via nanoprecipitation method.  

PubMed

The improvement of the solid content of the hydrophobic drugs (such as paclitaxel (PTX), etc.) loaded nanoparticles (NPs) dispersion is important for enhancing drug-loaded efficiency and reducing the cost in production and application. A diblock copolymer methoxy poly(ethylene glycol)-b-poly(?-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone) (mPECT) is synthesized via the ring-opening polymerization of ?-caprolactone and 1,4,8-trioxa[4.6]spiro-9-undecanone (TOSUO) with methoxy poly(ethyleneglycol) (mPEG? as the initiator. The chemical structures and thermal properties of mPECT are characterized by (1)HNMR, Fourier transform infrared (FT-IR), gel permeation chromatography, differential scanning calorimetry, etc. PEG45.45-b-P(C28.33-co-T5.38) (mPECT-2) is able to self-assemble into stable NPs in water via nanoprecipitation method at a high solid content (?25?wt%) and their freeze-dried powders can well re-disperse in water. The paclitaxel (PTX) is chosen as a hydrophobic drug model and successfully encapsulate into the mPECT-2 NPs via the same method at a high solid content. The encapsulation efficiency, cytotoxicity and in vitro release of PTX-loaded NPs are investigated. The results suggest that the behavior of the drug-loaded mPECT-2 NPs prepared at a solid content of 25?wt% is similar to that of NPs prepared at a solid content of 1?wt%, which indicate that increasing solid content of polymer has no negative effect on the properties of NPs dispersion in application. In summary, the freeze-dried NPs prepared from the high solid content dispersion (?25?wt%) has a good redispersibility and exhibits great potential in cost control of preparing NPs dispersion used as drug delivery system. PMID:24894948

Xiang, Yuzhang; Xiao, Miao; Han, Shangcong; Xu, Shuxin; Cao, Yan; Lv, Zesheng; Liu, Jianfeng; Liu, Jinjian; Deng, Liandong; Dong, Anjie

2014-01-01

400

Preparation of Chitosan Coated Magnetic Hydroxyapatite Nanoparticles and Application for Adsorption of Reactive Blue 19 and Ni2+ Ions  

PubMed Central

An adsorbent called chitosan coated magnetic hydroxyapatite nanoparticles (CS-MHAP) was prepared with the purpose of improvement for the removal of Ni2+ ions and textile dye by coprecipitation. Structure and properties of CS-MHAP were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). Weight percent of chitosan was investigated by thermal gravimetric analysis (TGA). The prepared CS-MHAP presents a significant improvement on the removal efficiency of Ni2+ ions and reactive blue 19 dye (RB19) in comparison with chitosan and magnetic hydroxyapatite nanoparticles. Moreover, the adsorption capacities were affected by several parameters such as contact time, initial concentration, adsorbent dosage, and initial pH. Interestingly, the prepared adsorbent could be easily recycled from an aqueous solution by an external magnet and reused for adsorption with high removal efficiency. PMID:24592158

Nguyen, Van Cuong; Pho, Quoc Hue

2014-01-01

401

Development of a novel and customizable two-solution mixing type spray nozzle for one-step preparation of nanoparticle-containing microparticles.  

PubMed

Production of drug nanoparticles is an effective strategy to enhance solubility and oral absorption of water-insoluble drugs. The handling of drug nanoparticles has been an important issue in drug formulation because nanoparticles easily aggregate each other and redispersion of these particles is very difficult. In the present study, we developed a unique two-solution mixing type spray nozzle that can prepare drug nanoparticles in microparticles in one step without any common solvent and surfactant, and then, the prepared formulation were evaluated. Ethylcellulose (EC) and mannitol (MAN) were used as a model polymer of water-insoluble compound and a water-soluble carrier, respectively. We characterized the EC/MAN microparticles produced by the novel spray nozzle when customizing the nozzle parts to mix EC and MAN solution. Relatively smaller EC nanoparticles (<110 nm) in MAN microparticles (approximately 3 µm) were obtained by changing the customizable parts in the nozzle. In addition, the core of EC nanoparticles (<50 nm) was also observed by atomic force microscopy. We also found that the mixing time in the nozzle parts affected the size and the standard deviation of EC nanoparticles. These results suggest that the size of EC nanoparticles in MAN microparticles is controllable by using this unique nozzle. After all, we could prepare MAN microparticles containing EC nanoparticles in one step by using the novel nozzle. The drug/MAN microparticles formulation produced by the nozzle may be useful for the handling of drug nanoparticles. PMID:23123464

Ozeki, Tetsuya; Akiyama, Yusuke; Takahashi, Norimitsu; Tagami, Tatsuaki; Tanaka, Toshiyuki; Fujii, Masashi; Okada, Hiroaki

2012-01-01

402

Active and stable liquid water innovatively prepared using resonantly illuminated gold nanoparticles.  

PubMed

The properties of confined liquid water, or liquid water in contact with hydrophobic surfaces, are significantly different from those of bulk liquid water. However, all of water's commonly described properties are related to inert "bulk liquid water" which comprises a tetrahedral hydrogen-bonded network. In this work, we report an innovative and facile method for preparing small water clusters (SWCs) with reduced affinity hydrogen bonds by letting bulk water flow through supported Au nanoparticles (NPs) under resonant illumination to give NP-treated (AuNT) water at constant temperature. Utilizing localized surface plasmon resonance on illuminated Au NPs, the strong hydrogen bonds of bulk water can be disordered when water is located at the illuminated Au/water interface. The prepared SWCs are free of Au NPs. The energy efficiency for creating SWCs is ?17%. The resulting stable AuNT water exhibits distinct properties at room temperature, which are significantly different from the properties of untreated bulk water, examples being their ability to scavenge free hydroxyl and 2,2-diphenyl-1-picrylhydrazyl radicals and to effectively reduce NO release from lipopolysaccharide-induced inflammatory cells. PMID:24533852

Chen, Hsiao-Chien; Hwang, Bing-Joe; Mai, Fu-Der; Liu, Yu-Chuan; Lin, Chun-Mao; Kuo, Hsien-Shou; Chou, Duen-Suey; Lee, Ming-Jer; Yang, Kuang-Hsuan; Yu, Chung-Chin; Chen, Jiun-Rong; Lo, Tsui-Yun; Tsai, Hui-Yen; Yang, Chih-Ping; Wang, Chi; Hsieh, Hsiao-Ting; Rick, John

2014-03-25

403

Preparation, formula optimization and antitumor actions of mannitol coupling camptothecin nanoparticles.  

PubMed

The purpose of this work is to prepare a formulation using mannitol coupling Camptothecin (CPT) nanoparticles (CPT-NPs) to circumvent the difficult solubilization practice based on central composite experimental statistical design. CPT-NPs were prepared with a high-pressure homogenization technique method. The independent variables considered for the optimization of CPT-NPs were percentage of CPT in raw material (CPT and mannitol), concentration of CPT in working liquid, cycles numbers and homogenizer pressure for drug loading efficiency, particle size and polydispersity index. Analysis of variance (ANOVA) statistical test was used to assess the optimization. The optimized CPT-NPs showed an appropriate drug loading efficiency (18.09 ± 2.13%), a homogeneous particle size (165.33 ± 37.23 nm) and a low polydispersity index (0.29 ± 0.01). The CPT-NPs group show higher inhibition ratio (79.95%) of H22 tumor growth in vivo compared with TPT and CPT at the same dose. Changes in mice body weight demonstrate CPT-NPs have the lower toxicity. The results of biodistribution studies indicated the obviously superiority of CPT-NPs in increasing the accumulation of CPT within tumor. Overall, CPT-NPs under optimum conditions are considered to be potentially feasible to overcome formulation challenges for drug delivery. PMID:24530520

Wang, Zhichao; Li, Qingyong; Zhao, Xiuhua; Sun, Baihe; Zhu, Qiaochu; Gao, Wenqing; Hua, Changlong

2014-04-25

404

Using supported Au nanoparticles as starting material for preparing uniform Au/Pd bimetallic catalysts  

SciTech Connect

One of the best methods for producing bulk homogeneous (composition) supported