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1

Preparation of cobalt-ferrite nanoparticles within a biopolymer template  

NASA Astrophysics Data System (ADS)

Using an in-situ co-precipitation reaction from solid dissolutions of stoichiometric amounts of Fe (III) and Co (II) inorganic salts, it was prepared highly loaded nanocomposites (as high as 75% w/w) of cobalt-ferrite nanoparticles within a chitosan matrix, with particle size of about 7 nm, narrow particle size distribution and superparamagnetic character. Nanocomposite samples were characterized by high resolution transmission electron microscopy (HRTEM), UV-vis spectrometry and magnetic measurements by SQUID, using magnetization-field dependent, M(H), and magnetization-temperature dependent, M(T), studies.

Garza, Marco; González, Virgilio; Torres-Castro, Alejandro; Hinojosa, Moisés; Ortíz, Ubaldo

2008-03-01

2

Preparation and characterization of the cobalt ferrite nano-particles by reverse coprecipitation  

NASA Astrophysics Data System (ADS)

In this paper, cobalt ferrite nano-particles were rapidly prepared using a reverse coprecipitation method. The effects of pH value, aging time, aging temperature and calcination temperature were studied by VSM, XRD and TEM. The results presented that the conditions to obtain the cobalt ferrite nano-particles with a perfect cubic spinel ferrite type structure are the pH value of 12.00, aging time of 60 min, aging temperature of 92 °C and calcination temperature of 800 °C. The crystallite size of cobalt ferrite increased with increasing the aging and calcination temperature. The saturation magnetization of cobalt ferrite increased with increasing the aging and calcination temperature. The VSM analysis demonstrated that the optimum sample has a high saturation magnetization and proper coercivity, 72.95 emu/g and 717 Oe, respectively. Furthermore, the particle size estimated from the TEM was seen to be larger than that observed from the XRD analysis.

Huixia, Feng; Baiyi, Chen; Deyi, Zhang; Jianqiang, Zhang; Lin, Tan

2014-04-01

3

Photocatalytic ozonation of dyes using copper ferrite nanoparticle prepared by co-precipitation method  

Microsoft Academic Search

In this paper, photocatalytic ozonation of dyes with copper ferrite (CuFe2O4) nanoparticle (CF nanoparticle) prepared by co-precipitation method was investigated. Reactive Red 198 (RR198) and Reactive Red 120 (RR120) were used as dye models. The characteristics of CF nanoparticle were studied using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). UV–Vis and ion chromatography (IC) analyses were employed to

Niyaz Mohammad Mahmoodi

2011-01-01

4

Magnetocaloric effect in ferrite nanoparticles  

Microsoft Academic Search

A comparative study of the magnetocaloric effect (MCE) is reported in two different types of chemically synthesized magnetic nanoparticle systems—cobalt ferrite and manganese zinc ferrite with mean size around 5 and 15nm, respectively. While CoFe2O4 nanoparticles were synthesized using co-precipitation, the Mn0.68Zn0.25Fe2.07O4 (MZFO) nanoparticles were prepared by reverse micelle technique using AOT as surfactant. Our results indicate that the change

P. Poddar; J. Gass; D. J. Rebar; S. Srinath; H. Srikanth; S. A. Morrison; E. E. Carpenter

2006-01-01

5

Preparation and characterization of complex ferrite nanoparticles by a polymer-pyrolysis route  

Microsoft Academic Search

The polymer-pyrolysis route used in this work was to synthesize the copolymeric precursor of the mixed metallic ions and then\\u000a to pyrolyze the precursor into complex spinel ferrite nanoparticles. Thermogravimetric analysis (TGA) showed that the complex\\u000a ferrite nanoparticles could be obtained by calcination of their precursors at 500°C. The structures, elemental analyses and\\u000a particle morphology of the as-calcined products were

Xian-Ming Liu; Shao-Yun Fu; Hong-Mei Xiao; Lu-Ping Zhu

2007-01-01

6

Highly aluminium doped barium and strontium ferrite nanoparticles prepared by citrate auto-combustion synthesis  

SciTech Connect

Aluminium doped barium and strontium hexaferrite nanoparticles BaAl {sub x}Fe{sub (12-x)}O{sub 19} and SrAl {sub x}Fe{sub (12-x)}O{sub 19} were synthesised via a sol-gel route using citric acid to complex the ions followed by an auto-combustion reaction. This method shows promise for the synthesis of complex ferrite powders with small particle size. It was found that around half of the iron could be substituted for aluminium in the barium ferrite with structure retention, whereas strontium aluminium ferrites could be produced with any aluminium content including total substitution of the iron. All synthesised materials consisted of particles smaller than 1 {mu}m, which is the size of a single magnetic domain, and various doping levels were achieved with the final elemental composition being within the bounds of experimental error. The materials show structural and morphological changes as they move from iron to aluminium ferrites. Such materials may be promising for imaging applications.

Shirtcliffe, Neil J. [Nottingham Trent University, Clifton Lane, Clifton, Nottingham NG11 8NS (United Kingdom)]. E-mail: neil.shirtcliffe@ntu.ac.uk; Thompson, Simon [Nottingham Trent University, Clifton Lane, Clifton, Nottingham NG11 8NS (United Kingdom); O'Keefe, Eoin S. [QinetiQ, Farnborough, Hampshire (United Kingdom); Appleton, Steve [QinetiQ, Farnborough, Hampshire (United Kingdom); Perry, Carole C. [Nottingham Trent University, Clifton Lane, Clifton, Nottingham NG11 8NS (United Kingdom)]. E-mail: carole.perry@ntu.ac.uk

2007-02-15

7

Synthesis, structural investigation and magnetic properties of Zn2+ substituted cobalt ferrite nanoparticles prepared by the sol-gel auto-combustion technique  

NASA Astrophysics Data System (ADS)

Structural morphology and magnetic properties of the Co1-xZnxFe2O4 (0.0?x?1.0) spinel ferrite system synthesized by the sol-gel auto-combustion technique using nitrates of respective metal ions have been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600 °C for 12 h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co-Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol-gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co-Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn2+ content in cobalt ferrite nanoparticles is followed by decrease in nB, Ms and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature.

Raut, A. V.; Barkule, R. S.; Shengule, D. R.; Jadhav, K. M.

2014-05-01

8

Magnetocaloric phenomena in Mg-ferrite nanoparticles  

Microsoft Academic Search

A comparative study of magnetocaloric effect (MCE) in superparamagnetic (SPM) regime is reported in two different types of magnesium ferrite nanostructures. The samples were prepared either by microemulsion method as MgFe2O4 nanoparticles encapsulated in amorphous SiO2, or as matrix-less nanoparticles using hydrothermal synthesis in supercritical water conditions. The particle diameter in all prepared samples was obtained from XRD measurements and

S. Burianova; J. Poltierova-Vejpravova; P. Holec; J. Plocek

2010-01-01

9

Preparation of magnesium ferrite nanoparticles by ultrasonic wave-assisted aqueous solution ball milling.  

PubMed

Magnesium ferrite, MgFe2O4 nanoparticles with high saturation magnetization were successfully synthesized using ultrasonic wave-assisted ball milling. In this study, the raw materials were 4MgCO3·Mg(OH)2·5H2O and Fe2O3 powders and the grinding media was stainless steel ball. The average particle diameter of the product MgFe2O4 powders was 20 nm and the saturation magnetization of them reached 54.8 emu/g. The different results of aqueous solution ball milling with and without ultrasonic wave revealed that it was the coupling effect of ultrasonic wave and mechanical force that played an important role during the synthesis of MgFe2O4. In addition, the effect of the frequency of the ultrasonic wave on the ball milling process was investigated. PMID:23622867

Chen, Ding; Li, Dian-yi; Zhang, Ying-zhe; Kang, Zhi-tao

2013-11-01

10

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

11

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

12

Magnetic Characterization of Ferrite Nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles (NPs) of different compositions (FeO/Fe3O4, g-Fe2O3, FePt, and CoFe2O4) have been synthesized using high temperature organometallic routes described elsewhere. NPs (16.6 nm in diameter) of a mixed FeO/Fe3O4 (wuestite/magnetite) composition were prepared by thermal decomposition or iron oleate in the presence of oleic acid as a surfactant in dodocane at 370C in argon atmosphere. After the thermal treatment of the reaction solution at 200 C under air for 2 hours these NPs are transformed into maghemite (g-Fe2O3), the magnetization of which is significantly enhanced. NPs of CoFe2O4 (8 nm) have been prepared by simultaneous decomposition of Co(II) and Fe(III) acetylacetonates in the presence of oleic acid and oleylamine. The X-ray diffraction profile of these NPs is characteristic of cobalt ferrite. Alternatively, alloyed 1.8 nm FePt NPs prepared by simultaneous decomposition of Fe and Pt acetylacetonates in the reductive environment demonstrate a completely disordered structure, which is reflected in their magnetic properties. SQUID magnetometry was used to measure the magnetization of NPs at high and low temperatures. Zero-field cooling and field-cooling measurements were taken to demonstrate superparamagnetic behavior and an associated blocking temperature.

Bryan, Matthew; Sokol, Paul; Gumina, Greg; Bronstein, Lyudmila; Dragnea, Bogdan

2011-03-01

13

Low temperature chemical synthesis of ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrite nanoparticles of Ni0.4Zn0.6-xMnxFe2O4 where x varies from 0 to 0.25 in steps of 0.05 using metal nitrates were prepared by low temperature sol-gel autocombustion method in citric acid matrix. XRD patterns of all the samples exhibit spinel crystal structures and the crystallite sizes estimated using Scherrer equation have been found to be about 30 nm. TEM measurements on these nanoparticles showed the particle sizes to be around 32 nm which are in conformity with the crystallite sizes obtained through XRD. The magnetic measurements carried out using VSM on these NiZn ferrite nanoparticles showed good magnetic performance with Mn substitutions. Deviations, if any, in magnetic properties are attributed to the increased degree of inversion in cationic distributions and also to the spin disorder at the surfaces which contributes to decreased magnetic strength of the cations present in different lattice sites.

Ramesh, S.; Rao, S. N. R.; Rao, B. Parvatheeswara; Subba Rao, P. S. V.

2012-07-01

14

Lithium ferrite nanoparticles for ferrofluid applications  

NASA Astrophysics Data System (ADS)

Nanoparticles of Lithium ferrite in the particle size range of 10 nm have been prepared by a citrate precursor method at a relatively low temperature of 200°C. The particles show characteristic infra red (IR) spectrum of lithium ferrite and broadened X-ray diffraction (XRD) patterns typical of the nanoparticle nature. The sample decomposed at 200°C has the ?-LiFe 5O 8 type (a disordered type of spinel) structure which on annealing at 350°C transforms to the ?-LiFe 5O 8 type (an ordered type spinel) structure as shown by both IR spectra and XRD studies. Magnetization curves indicate a particle size distribution consisting of both ferromagnetic particles and a superparamagnetic fraction. With 4 ?Ms values of 2000 G these particles could be useful for applications in certain low magnetization ferrofluids.

Sankaranarayanan, V. K.; Prakash, Om; Pant, R. P.; Islam, Mohammad

2002-11-01

15

Physical and magnetic properties of highly aluminum doped strontium ferrite nanoparticles prepared by auto-combustion route  

NASA Astrophysics Data System (ADS)

Highly Al3+ ion doped nanocrystalline SrFe12-xAlxO19 (0?x?12), were prepared by the auto-combustion method and heat treated in air at 1100 °C for 12 h. The phase identification of the powders performed using x-ray diffraction show presence of high-purity hexaferrite phase and absence of any secondary phases. With Al3+ doping, the lattice parameters decrease due to smaller Al3+ ion replacing Fe3+ ions. Morphological analysis performed using transmission electron microscope show growth of needle shaped ferrites with high aspect ratio at Al3+ ion content exceeding x?2. Al3+ substitution modifies saturation magnetization (MS) and coercivity (HC). The room temperature MS values continuously reduced while HC value increased to a maximum value of 18,100 Oe at x=4, which is an unprecedented increase (˜321%) in the coercivity as compared to pure Sr-Ferrite. However, at higher Al3+ content x>4, a decline in magnetization and coercivity has been observed. The magnetic results indicate that the best results for applications of this ferrite will be obtained with an iron deficiency in the stoichiometric formulation.

Luo, H.; Rai, B. K.; Mishra, S. R.; Nguyen, V. V.; Liu, J. P.

2012-08-01

16

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

Microsoft Academic Search

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

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

2009-01-01

17

Magnetocaloric effect (MCE) in Nickel Ferrite nanoparticles  

Microsoft Academic Search

We report on the magneto caloric effect (MCE) in a Nickel ferrite (NiFe2O4) nanoparticle system. The nanoparticles were synthesized using chemical co-precipitation. Extensive characterization of structural and magnetic properties was done using XRD, TEM, DC and AC magnetization, and transverse susceptibility. The change in entropy was calculated using the thermodynamic Maxwell relation from the family of M-H curves taken at

J. Gass; M. B. Morales; N. A. Frey; M. J. Miner; S. Srinath; H. Srikanth

2007-01-01

18

Magnetocaloric effect (MCE) in ferrite nanoparticles  

Microsoft Academic Search

Enhancement of the magnetocaloric effect (MCE) in nanostructured materials is important for refrigeration applications particularly in potential spot cooling of MEMS and NEMS devices. We have investigated MCE in various classes of polydisperse and monodisperse soft ferrite nanoparticles with different blocking characteristics. Our observations indicate that in some systems, surface properties such as spin disorder and anisotropy lead to considerable

James Gass; Hariharan Srikanth

2008-01-01

19

Preparation of ferrite-coated MFM cantilevers  

NASA Astrophysics Data System (ADS)

Ferrite-coated magnetic force microscopy (MFM) cantilevers were prepared for the use with a high-frequency MFM (HF-MFM) setup. The ferrite coatings were fabricated by means of radio frequency (RF) magnetron sputtering directly on the Si surface. Two types of ferrites were employed in this study: NiZnFe 2O 4 spinel and Co 2Z-type hexaferrite (Ba 3Co 2Fe 24O 41, BCFO). The typical thickness of the coatings was 50 nm. For comparison, ferrite samples on (1 0 0) and (1 1 1)-oriented Si substrates (analogous to the surfaces of the cantilevers) were prepared. Successful HF-MFM imaging was performed with both types of cantilevers using harddisk writer poles as samples. The HF-MFM images obtained by ferrite-coated cantilevers evidently reveal more details of the magnetic field distribution of the writer poles up to the GHz range than conventional CoCr-coated MFM cantilevers.

Koblischka, M. R.; Kirsch, M.; Wei, J.; Sulzbach, T.; Hartmann, U.

2007-09-01

20

Ferrite nanoparticles for future heart diagnostics  

NASA Astrophysics Data System (ADS)

Normally, CoFe2O4 has been known as ferromagnetic ferrite with a quite large magnetic moment. However, since we aim to inject the particles into the human body, we are also interested in ZnFe2O4 because in the human body, Fe and Zn exist, so that adding ZnFe2O4 is safer. In both cases, the nanoparticles are coated by silica in order to get rid of toxicity. Our main purpose is to test whether these nanoparticles affect the contractile function of heart cells. Our results on rat's heart cells have shown that both Zn and Co ferrites improved the contractility of heart cells. Notably, although both nanoparticles increased contraction and delayed relaxation, Co ferrites induced a greater contraction but with a slower relaxation. We can theoretically argue that the magnetization effects of the quantum dots have a considerable effect on the pulsating properties of the heart cells. Through this effect, the locally applied magnetic field is able to induce as well as turn on/off various regular beating patterns, thus, resetting the heart beatings.

Hong, Nguyen Hoa; Raghavender, A. T.; Ciftja, O.; Phan, M.-H.; Stojak, K.; Srikanth, H.; Zhang, Yin Hua

2013-08-01

21

Atomic engineering of mixed ferrite and core-shell nanoparticles.  

PubMed

Nanoparticulate ferrites such as manganese zinc ferrite and nickel zinc ferrite hold great promise for advanced applications in power electronics. The use of these materials in current applications requires fine control over the nanoparticle size as well as size distribution to maximize their packing density. While there are several techniques for the synthesis of ferrite nanoparticles, reverse micelle techniques provide the greatest flexibility and control over size, crystallinity, and magnetic properties. Recipes for the synthesis of manganese zinc ferrite, nickel zinc ferrite, and an enhanced ferrite are presented along with analysis of the crystalline and magnetic properties. Comparisons are made on the quality of nanoparticles produced using different surfactant systems. The importance of various reaction conditions is explored with a discussion on the corresponding effects on the magnetic properties, particle morphology, stoichiometry, crystallinity, and phase purity. PMID:16193949

Morrison, Shannon A; Cahill, Christopher L; Carpenter, Everett E; Calvin, Scott; Harris, Vincent G

2005-09-01

22

Preparation and magnetic properties of Zn-Cu-Cr-La ferrite and its nanocomposites with polyaniline.  

PubMed

Nanosized Zn(0.6)Cu(0.4)Cr(0.5)Fe(1.5-x)La(x)O(4) (x=0 - 0.06) ferrites doped with La are synthesized by a rheological phase reaction method. Polyaniline (PANI)/ferrite nanocomposites are prepared by in situ polymerization method. The structure, morphology and ferromagnetic property of ferrite powders and nanocomposites are characterized by X-ray powder diffractometer (XRD), transmission electron microscope (TEM), Fourier transform infrared spectra (FTIR), UV-visible spectroscopy (UV), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). The results indicate that the PANI and nanosized ferrite powders can be combined effectively. The polymers can reduce the agglomeration of nanosized ferrite particles to some extent, which is good for the dispersedness and stabilization of nanoparticles. The PANI/ferrite nanocomposites under applied magnetic field exhibit the hysteretic loops of the ferromagnetic nature. The magnetic properties of nanocomposites are tailored by controlling the ferrite content. PMID:18313067

Li, Liangchao; Liu, Hui; Wang, Yuping; Jiang, Jing; Xu, Feng

2008-05-15

23

A new synthesis route from spent sulfuric acid pickling solution to ferrite nanoparticles  

Microsoft Academic Search

This paper describes a new synthesis route to magnetic ferrite nanoparticles, in which the dissolved ferrous iron(II) in spent pickling solutions is used as a starting material for the ferrite preparation. Firstly, the iron(II) in the spent pickling solution was microbially oxidized to iron(III) by using the acidophilic thermophilic microbe Acidianus brierleyi. Secondly, the iron(III) in the oxidized pickling solution

Yasuhiro Konishi; Toshiyuki Nomura; Kazunari Mizoe

2004-01-01

24

Fabrication of Mn-ferrite nanoparticles from MnO colloids.  

PubMed

The reaction mechanism for conversion of MnO nanoparticles to Mn-ferrite nanoparticles was studied, which involved sequential consumption of MnO and the growth of ferrite. The method could be applied to other ferrite nanoparticles including cobalt ferrite. PMID:19885477

Han, Anna; Choi, Donghyuk; Kim, Taehei; Lee, Jei Hee; Kim, Jai Keun; Yoon, Mi Jin; Choi, Kyeong Sook; Kim, Sang-Wook

2009-11-28

25

Cobalt ferrite nanoparticles: The control of the particle size and surface state and their effects on magnetic properties  

Microsoft Academic Search

In order to improve the efficacy of magnetic fluid hyperthermia (MFH) mediators, we synthesised cobalt ferrite nanoparticles with different sizes (between 5 and 7nm) via successive polyol synthesis. The static and dynamic magnetic properties of the prepared particles, dispersed in a solid matrix, were investigated in order to evaluate the possibility of applying cobalt ferrite as magnetic susceptors in MFH.

Giovanni Baldi; Daniele Bonacchi; Claudia Innocenti; Giada Lorenzi; Claudio Sangregorio

2007-01-01

26

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

27

Dielectric properties of cobalt ferrite nanoparticles in ultrathin nanocomposite films.  

PubMed

Multilayered nanocomposite films (thickness 50-90 nm) of cobalt ferrite nanoparticles (np-CoFe2O4, 18 nm) were deposited on top of interdigitated microelectrodes by the layer-by-layer technique in order to study their dielectric properties. For that purpose, two different types of nanocomposite films were prepared by assembling np-CoFe2O4 either with poly(3,4-ethylenedioxy thiophene):poly(styrene sulfonic acid) or with polyaniline and sulfonated lignin. Despite the different film architectures, the morphology of both was dominated by densely-packed layers of nanoparticles surrounded by polyelectrolytes. The dominant effect of np-CoFe2O4 was also observed after impedance spectroscopy measurements, which revealed that dielectric behavior of the nanocomposites was largely influenced by the charge transport across nanoparticle-polyelectrolyte interfaces. For example, nanocomposites containing np-CoFe2O4 exhibited a single low-frequency relaxation process, with time constants exceeding 15 ms. At 1 kHz, the dielectric constant and the dissipation factor (tan ?) of these nanocomposites were 15 and 0.15, respectively. These values are substantially inferior to those reported for pressed pellets made exclusively of similar nanoparticles. Impedance data were further fitted with equivalent circuit models from which individual contributions of particle's bulk and interfaces to the charge transport within the nanocomposites could be evaluated. The present study evidences that such nanocomposites display a dielectric behavior dissimilar from that exhibited by their individual counterparts much likely due to enlarged nanoparticle-polyelectrolyte interfaces. PMID:24145704

Alcantara, Gustavo B; Paterno, Leonardo G; Fonseca, Fernando J; Pereira-da-Silva, Marcelo A; Morais, Paulo C; Soler, Maria A G

2013-12-01

28

Ferrite Nanoparticles, Films, Single Crystals, and Metamaterials: High Frequency Applications  

SciTech Connect

Ferrite materials have long played an important role in power conditioning, conversion, and generation across a wide spectrum of frequencies (up to ten decades). They remain the preferred magnetic materials, having suitably low losses, for most applications above 1 MHz, and are the only viable materials for nonreciprocal magnetic microwave and millimeter-wave devices (including tunable filters, isolators, phase shifters, and circulators). Recently, novel processing techniques have led to a resurgence of research interest in the design and processing of ferrite materials as nanoparticles, films, single crystals, and metamaterials. These latest developments have set the stage for their use in emerging technologies that include cancer remediation therapies such as magnetohyperthermia, magnetic targeted drug delivery, and magneto-rheological fluids, as well as enhanced magnetic resonance imaging. With reduced dimensionality of nanoparticles and films, and the inherent nonequilibrium nature of many processing schemes, changes in local chemistry and structure have profound effects on the functional properties and performance of ferrites. In this lecture, we will explore these effects upon the fundamental magnetic and electronic properties of ferrites. Density functional theory will be applied to predict the properties of these ferrites, with synchrotron radiation techniques used to elucidate the chemical and structural short-range order. This approach will be extended to study the atomic design of ferrites by alternating target laser-ablation deposition. Recently, this approach has been shown to produce ferrites that offer attractive properties not found in conventionally grown ferrites. We will explore the latest research developments involving ferrites as related to microwave and millimeter-wave applications and the attempt to integrate these materials with semiconductor materials platforms.

Harris,V.

2006-01-01

29

Ni3Zn ferrite octahedral nanoparticles with high microwave permeability and high magnetic loss tangent  

NASA Astrophysics Data System (ADS)

Ni3Zn ferrite octahedral nanoparticles with grain size of about 40 nm were synthesized via a low temperature hydrothermal route. The saturation magnetization (Ms) and coercive force (Hc) of the sample are 57.5 emu/g and 197 Oe, respectively. In 50 MHz-8 GHz frequency range, the complex permeability and complex permittivity for Ni3Zn ferrite/wax composites containing 60 wt% ferrite powders were measured by a vector network analyzer. The real part ?r' of the permeability exhibits high values between 4 and 1.65 in 50 MHz-2 GHz range, and the imaginary part ?r'' of the permeability presents a broad peak with a maximum value of 1.53 at 2.1 GHz, the calculated reflection loss of ferrite/wax coating with the thickness of 8 mm reaches -13 dB at 2.1 GHz. The results indicate the as-prepared Ni3Zn ferrite octahedral nanoparticles can have applications in biomedicine, and microwave absorption and electric devices.

Wang, Zhongzhu; Wu, Mingzai; Jin, Shaowei; Li, Guang; Ma, Yongqing; Wang, Peihong

2013-10-01

30

Finite size and surface effects on the magnetic properties of cobalt ferrite nanoparticles  

Microsoft Academic Search

Cobalt ferrite, CoFe2O4, nanoparticles in the size range 2–15 nm have been prepared using a non-aqueous solvothermal method. The magnetic studies\\u000a indicate a superparamagnetic behavior, showing an increase in the blocking temperatures (ranging from 215 to more than 340 K)\\u000a with the particle size, D\\u000a TEM. Fitting M versus H isotherms to the saturation approach law, the anisotropy constant, K, and the

C. Vázquez-Vázquez; M. A. López-Quintela; M. C. Buján-Núñez; J. Rivas

2011-01-01

31

Synthesis and charcterization of Nanocrystalline NiCuZn Ferrite prepared by Sol-gel auto combution method  

NASA Astrophysics Data System (ADS)

Promising future applications of ferrite nanoparticles in medicine, making many devices like permanent magnets, memory storage devices etc. Ferrite nanoparticles have been the emerging focus of the recent scientific research. Therefore nanostructured powders of ferrites having chemical compositions [Ni0.8-xCu0.2Znxfe2O4], where x=0.3, 0.5, synthesised through nitrate citrate by sol-gel autocombustion method from stoichiometric mixture of their respective metal nitrate. The prepared powders were sintered at 400 0C and 600 0C for 4 hours. The structural, morphology, ferrite formation of powder were determined by X-ray powder diffractometry (XRD), Scanning Electron Microscope (SEM) photograph of the samples and Infrared (IR) spectroscopy technique. The X-ray revealed the formation of nano-sized ferrite particles with cubic spinel structure and the cubic phase in the ferrite matrix. The IR shows the characteristic ferrite bonds were confirmed. The average crystalline particles sized were calculated by Scherrer formula. The average crystalline size obtained from XRD was found between 40 and 44nm. The lattice parameters, X-ray density and bond length are different parameters are calculated from XRD patterns. The UV-Visible Spectroscopy of prepared sample shows that the band gap energy in the range of semiconductor materials. The Coercivity was found to change in proportionally and sintering temperature with the particle sizes of the investigated ferrites.

Rathod, Sopan M.; Shinde, Ashok B.

2012-11-01

32

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

33

Cobalt-ferrite nanoparticles: Structure, cation distributions, and magnetic properties  

NASA Astrophysics Data System (ADS)

Cobalt-ferrite nanoparticles have been synthesized in water-in-oil microemulsions (reversed micelles) with varying cation composition. The microenvironment provides a template effect that controls the size and particle shape. Transmission electron microscopy reveals that the particles are nanospheres with particle size ranging from 12 to 18 nm. X-ray diffraction results indicate that at low Co2+:Fe2+ ratio (1:10 and 1:5) in the precursor, the particles retain an essentially ferrite structure (?-Fe2O3). However, the cobalt-ferrite phase (CoFe2O4) forms upon further increase of the Co2+ content. The materials are found to exhibit superparamagnetism. The blocking temperatures and coercivities are dependent on the Co2+:Fe2+ ratio in the system.

Li, Sichu; John, Vijay T.; O'Connor, Charles; Harris, Vincent; Carpenter, Everett

2000-05-01

34

Magnetic micromachines prepared by ferrite plating technique  

NASA Astrophysics Data System (ADS)

By the sterolithography technique and the ferrite plating, we fabricated three types of magnetic micromachines which coated Fe3O4, Co0.39Fe2.61O4, and Co0.45Fe2.55O4, respectively. The stereolithography technique enables one to form the spiral-shape resinous templates and the ferrite plating enables one to coat the ferrites uniformly onto these templates from an aqueous solution. The total machine weight is light because a resin of the template body is almost the same density as water. We verified that the machines swim freely and wirelessly in water by applying a rotational magnetic field. As these machines coated with ferrites have the biocompatibility, there is the possibility of medical microrobots which swim in the human body for medical operations.

Nishimura, K.; Uchida, H.; Inoue, M.; Sendoh, M.; Ishiyama, K.; Arai, K. I.

2003-05-01

35

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

PubMed

?-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. PMID:24858357

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

2014-11-11

36

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

37

Mn–ferrite nanoparticles via reverse microemulsions: synthesis and characterization  

Microsoft Academic Search

Mn–ferrite nanoparticles were synthesized by thermal treatment at 800 °C of manganese and iron oxo-hydroxides obtained via\\u000a water-in-oil microemulsions consisting of n-hexanol as continuous phase, cetyl trimethyl ammonium bromide (CTAB) as the cationic surfactant and aqueous solutions of\\u000a metal salts and precipitant agent (tetramethyl ammonium hydroxide) as reagents. Nanoparticles were synthesized using a multi-microemulsion\\u000a approach. Two different co-precipitation routes are described

Alessandra Scano; Guido Ennas; Francesca Frongia; Aurelio La Barbera; M. Arturo López-Quintela; Giaime Marongiu; Giorgio Paschina; Davide Peddis; Martina Pilloni; Carlos Vázquez-Vázquez

2011-01-01

38

Size-dependent magnetic properties of calcium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

The union of nanotechnology with the other fields of science heralds the influx of many newer and better technologies, with the capability to revolutionize the human life. In the present work, calcium ferrite nanoparticles were synthesized by conventional sol-gel method and were characterised by X-ray diffraction, Transmission electron microscope, Vibrating sample magnetometer and Fourier transform infrared spectroscope. The synthesized nanoparticles were calcined at different temperatures and their magnetic behaviour was studied. The synthesized nanoparticles calcined at 900 °C were formed in the shape of capsules and exhibited mixed characteristics of ferrimagnetic and paramagnetic grains with magnetic saturation of 0.85 emu/g whereas nanoparticles calcined at 500 °C were spherical in shape and exhibited superparamagnetic characteristics with saturation magnetization of 37.67 emu/g.

Khanna, Lavanya; Verma, N. K.

2013-06-01

39

Effect of Mg substitution on the magnetic properties of NiCuZn ferrite nanoparticles prepared through a novel method using egg white  

NASA Astrophysics Data System (ADS)

Nanocrystalline Mg-substituted NiCuZn ferrites were successfully synthesized, for the first time, by using metal nitrates and freshly extracted egg white. The thermal decomposition process of the nitrate-egg white precursors was investigated by thermogravimetric (TG) technique. X-ray diffraction (XRD) revealed that, single-phase cubic ferrites with average particle size of 23.9-35.1 nm were directly formed after ignition at 500 °C. No noticeable variation of lattice parameters with increasing magnesium content was observed, while X-ray densities were found to decrease. This can be explained on the basis of ionic radii and atomic masses of the substituted cation. Transmission electron microscope (TEM) shows that, particles are permanently magnetized and get agglomerated. The saturation magnetization ( M s) and coercivity ( H c) as a function of Mg content were investigated using vibrating sample magnetometer (VSM). It has been found that the M s increases firstly up to x=0.2 and then decreases, while H c continuously decreases. Magnetic susceptibility measurements give results which agree well with those obtained by VSM. The obvious decrease in the Curie temperature ( T C) with increasing Mg indicates that the ferrimagnetic grains are widely separated and enclosed by non-magnetic magnesium ions.

Gabal, M. A.

2009-10-01

40

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

41

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

2014-05-01

42

Surface effects in the magnetic properties of crystalline 3 nm ferrite nanoparticles chemically synthesized  

NASA Astrophysics Data System (ADS)

We have systematically studied the magnetic properties of ferrite nanoparticles with 3, 7, and 11 nm of diameter with very narrow grain size distributions. Samples were prepared by the thermal decomposition of Fe(acac)3 in the presence of surfactants giving nanoparticles covered by oleic acid. High resolution transmission electron microscopy (HRTEM) images and XRD diffraction patterns confirms that all samples are composed by crystalline nanoparticles with the spinel structure expected for the iron ferrite. ac and dc magnetization measurements, as well in-field Mössbauer spectroscopy, indicate that the magnetic properties of nanoparticles with 11 and 7 nm are close to those expected for a monodomain, presenting large MS (close to the magnetite bulk). Despite the crystalline structure observed in HRTEM images, the nanoparticles with 3 nm are composed by a magnetically ordered region (core) and a surface region that presents a different magnetic order and it contains about 66% of Fe atoms. The high saturation and irreversibility fields in the M(H) loops of the particles with 3 nm together with the misalignment at 120 kOe in the in-field Mössbauer spectrum of surface component indicate a high surface anisotropy for the surface atoms, which is not observed for the core. For T<10 K, we observe an increase in the susceptibility and of the magnetization for former sample, indicating that surface moments tend to align with applied field increasing the magnetic core size.

Lima, E.; de Biasi, E.; Mansilla, M. Vasquez; Saleta, M. E.; Effenberg, F.; Rossi, L. M.; Cohen, R.; Rechenberg, H. R.; Zysler, R. D.

2010-11-01

43

Dielectric properties of Mn0.5Zn0.5Fe2O4 ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Mn0.5Zn0.5Fe2O4 ferrite nanoparticles have been prepared by sol-gel auto-combustion method with a view to understand the role of oxidizer to fuel ratio (OFR) on the dielectric properties. XRD study shows the formation of cubic ferrite with spinel structure and particle size increases with the increase in concentration of fuel. Dielectric properties and AC conductivity of the sample measured at room temperature are reported. OFR plays a vital role in determining the dielectric properties and AC conductivity of the prepared samples.

Murugesan, C.; Md Gazzali, P. M.; Sathyamoorthy, B.; Chandrasekaran, G.

2013-02-01

44

Study of magnetic and structural properties of ferrofluids based on cobalt-zinc ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 30 nm, dispersed in a liquid carrier. Magnetic Co (1- x) Zn xFe 2O 4 ( x=0.25, 0.50, 0.75) ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through Energy Dispersive X-ray Spectroscopy and X-ray diffraction, respectively. Transmission Electron Microscopy (TEM) studies permitted determining nanoparticle size; grain size of nanoparticle conglomerates was established via Atomic Force Microscopy. The magnetic behavior of ferrofluids was characterized by Vibrating Sample Magnetometer (VSM); and finally, a magnetic force microscope was used to visualize the magnetic domains of Co (1- x) Zn xFe 2O 4 nanoparticles. X-ray diffraction patterns of Co (1- x) Zn xFe 2O 4 show the presence of the most intense peak corresponding to the (311) crystallographic orientation of the spinel phase of CoFe 2O 4. Fourier Transform Infrared Spectroscopy confirmed the presence of the bonds associated to the spinel structures; particularly for ferrites. The mean size of the crystallite of nanoparticles determined from the full-width at half maximum of the strongest reflection of the (311) peak by using the Scherrer approximation diminished from (9.5±0.3) nm to (5.4±0.2) nm when the Zn concentration increases from 0.21 to 0.75. The size of the Co-Zn ferrite nanoparticles obtained by TEM is in good agreement with the crystallite size calculated from X-ray diffraction patterns, using Scherer's formula. The magnetic properties investigated with the aid of a VSM at room temperature presented super-paramagnetic behavior, determined by the shape of the hysteresis loop. In this study, we established that the coercive field of Co (1- x) Zn xFe 2O 4 magnetic nanoparticles, the crystal and nanoparticle sizes determined by X-ray Diffraction and TEM, respectively, decrease with the increase of the Zn at%. Finally, our magnetic nanoparticles are not very hard magnetic materials given that the hysteresis loop is small and for this reason Co (1- x) Zn xFe 2O 4 nanoparticles are considered as soft magnetic material.

López, J.; González-Bahamón, L. F.; Prado, J.; Caicedo, J. C.; Zambrano, G.; Gómez, M. E.; Esteve, J.; Prieto, P.

2012-02-01

45

Magnetic properties of substituted strontium ferrite nanoparticles and thin films  

NASA Astrophysics Data System (ADS)

SrFe 12-x(Zr 0.5Mg 0.5) xO 19 nanoparticles and thin films with x=0-2.5 were synthesized by a sol-gel method on thermally oxidized silicon wafer (Si/SiO 2). Structural and magnetic characteristics of synthesized samples were studied employing x-rays diffraction (XRD), transmission electron microscopy (TEM), magnetic susceptometer, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM). TEM micrographs display that the narrow size distribution of ferrite nanoparticles with average particle size of 50 nm were fabricated. Fitting obtained data of effective magnetic susceptibility by Vogel-Fulcher law confirms the existence of strong magnetic interaction among fine particles. XRD patterns and FE-SEM micrographs demonstrated that single phase c-axis hexagonal ferrite films with rather narrow grain size distribution were obtained. AFM micrographs exhibited that the surface roughness increases with an increase in Zr-Mg content. It was found from the VSM graphs that with an increase in substitution contents the coercivity decreases, while the saturation of magnetization increases. The Henkle plots confirms the existence of exchange coupling among nano-grain in ferrite thin films.

Ghasemi, Ali

2012-04-01

46

Study of Zn-Cu Ferrite Nanoparticles for LPG Sensing  

PubMed Central

Nanostructured zinc-copper mixed ferrite was synthesized using sol-gel method. XRD patterns of different compositions of zinc-copper ferrite, Zn(1?x)CuxFe2O4 (x = 0.0, 0.25, 0.50, 0.75), revealed single phase inverse spinel ferrite in all the samples synthesized. With increasing copper concentration, the crystallite size was found to be increased from 28?nm to 47?nm. The surface morphology of all the samples studied by the Scanning Electron Microscopy there exhibits porous structure of particles throughout the samples. The pellets of the samples are prepared for LPG sensing characteristics. The sensing is carried out at different operating temperatures (200, 225, and 250°C) with the variation of LPG concentrations (0.2, 0.4, and 0.6 vol%). The maximum sensitivity of 55.33% is observed at 250°C operating for the 0.6 vol% LPG.

Jain, Anuj; Baranwal, Ravi Kant; Bharti, Ajaya; Vakil, Z.; Prajapati, C. S.

2013-01-01

47

Influence of ferrite nanoparticle type and content on the crystallization kinetics and electroactive phase nucleation of poly(vinylidene fluoride).  

PubMed

This work reports on the nucleation of the ?-phase of poly(vinylidene fluoride) (PVDF) by incorporating CoFe(2)O(4) and NiFe(2)O(4) nanoparticles, leading in this way to the preparation of magnetoelectric composites. The fraction of filler nanoparticles needed to produce the same ?- to ?-phase ratio in crystallized PVDF is 1 order of magnitude lower in the cobalt ferrite nanoparticles. The interaction between nanoparticles and PVDF chains induce the all-trans conformation in PVDF segments, and this structure then propagates in crystal growth. The nucleation kinetics is enhanced by the presence of nanoparticles, as corroborated by the increasing number of spherulites with increasing nanoparticle content and by the variations of the Avrami's exponent. Further, the decrease of the crystalline fraction of PVDF with increasing nanoparticle content indicates that an important fraction of polymer chains are confined in interphases with the filler particle. PMID:21545124

Sencadas, Vitor; Martins, Pedro; Pitães, Alexandre; Benelmekki, Maria; Gómez Ribelles, José Luis; Lanceros-Mendez, Senentxu

2011-06-01

48

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

49

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 (MR/MS? 1), suggesting cubic anisotropy in the system, whereas for the NP sample, typical features of uniaxial anisotropy (MR/MS? 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 (KE) of the system. A high-temperature enhancement of HC and KE 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

50

Effect of samarium substitution on structural and magnetic properties of magnesium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Samarium doped magnesium ferrite was prepared (MgSmxFe2-xO4) by sol-gel method. X-ray diffraction analysis reveals that the samples are single phasic with crystallite sizes in the 13-25 nm regime. Increase in lattice parameter with doping concentration suggests the expansion in unit cell with Sm3+ doping. Fourier Transform Infrared Spectrum shows substitution of Sm3+ ions in octahedral B site. Transmission Electron Micrograph shows the spherical shape of nano-particles. Magnetic measurement shows a decrease in magnetization with doping which is explained using dependence on particle size.

Thankachan, Smitha; Jacob, Binu P.; Xavier, Sheena; Mohammed, E. M.

2013-12-01

51

Conjugation of manganese ferrite nanoparticles to an anti Sticholysin monoclonal antibody and conjugate applications  

Microsoft Academic Search

In this study the potential applications of manganese ferrite (MnFe2O4) nanoparticles for bioanalytical applications are evaluated. These magnetic nanoparticles show peroxidase-like activity similar to that reported for magnetite nanoparticles and peroxidase enzyme. Based on this finding, colloidal suspensions of manganese ferrite were conjugated to an anti-Sticholysin II (StII) monoclonal antibody. The resulting conjugate was then used as a revealing tool

V. Figueroa-Espí; A. Alvarez-Paneque; M. Torrens; A. J. Otero-González; E. Reguera

2011-01-01

52

Preparation and characterization of nanometric Mn ferrite via different methods  

Microsoft Academic Search

The structure and magnetic properties of MnFe2O4 ferrites have been investigated using five different preparation methods, including the ceramic technique, flash combustion, co-precipitation, sol-gel and citrate methods. The characteristics of one sample prepared by different methods have been studied to select the better method, i.e. the one that is the simplest and does not require an elaborate instrumental set-up. The

M. A. Ahmed; N. Okasha; S. I. El-Dek

2008-01-01

53

Preparation and magnetic properties of nano size nickel ferrite particles using hydrothermal method  

PubMed Central

Background Nickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe2O4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate) on the particles growth is investigated. Methods For investigation of the inhibition effect of surfactant on NiFe2O4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and inductively coupled plasma atomic emission spectrometer (ICP-AES) techniques were used to characterize the samples. Results The results of XRD and ICP-AES show that the products were pure NiFe2O4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm-1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe2O4 nanoparticles were in the range of 39.60 emu/g and 15.67 Qe that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature. Conclusions Nanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of NiFe2O4 nanoparticles decreased in comparison with surfactant- free prepared samples. All of the nickel ferrite nanoparticles were superparamagnetic at room temperature. Graphical abstract

2012-01-01

54

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

55

Cytotoxicity of nickel zinc ferrite nanoparticles on cancer cells of epithelial origin  

PubMed Central

In this study, in vitro cytotoxicity of nickel zinc (NiZn) ferrite nanoparticles against human colon cancer HT29, breast cancer MCF7, and liver cancer HepG2 cells was examined. The morphology, homogeneity, and elemental composition of NiZn ferrite nanoparticles were investigated by scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy, respectively. The exposure of cancer cells to NiZn ferrite nanoparticles (15.6–1,000 ?g/mL; 72 hours) has resulted in a dose-dependent inhibition of cell growth determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The quantification of caspase-3 and -9 activities and DNA fragmentation to assess the cell death pathway of the treated cells showed that both were stimulated when exposed to NiZn ferrite nanoparticles. Light microscopy examination of the cells exposed to NiZn ferrite nanoparticles demonstrated significant changes in cellular morphology. The HepG2 cells were most prone to apoptosis among the three cells lines examined, as the result of treatment with NiZn nanoparticles. In conclusion, NiZn ferrite nanoparticles are suggested to have potential cytotoxicity against cancer cells.

Al-Qubaisi, Mothanna Sadiq; Rasedee, Abdullah; Flaifel, Moayad Husein; Ahmad, Sahrim HJ; Hussein-Al-Ali, Samer; Hussein, Mohd Zobir; Eid, Eltayeb EM; Zainal, Zulkarnain; Saeed, Mohd; Ilowefah, Muna; Fakurazi, Sharida; Isa, Norhaszalina Mohd; Zowalaty, Mohamed Ezzat El

2013-01-01

56

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

57

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.

2014-01-01

58

Synthesis and characterization of silica coated potassium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Silica coated potassium ferrite nanoparticles (KFeO2 NPs) have been synthesized by conventional stöber process. The orthorhombic structure of KFeO2 NPs has been retained even after silica coating, only a slight variation has been observed in the angle range of 20°-25° (occurring due to amorphous silica), as shown by the X-ray diffraction pattern. The crystallite size using Scherrer's formula of bare and silica coated KFeO2 NPs has been calculated to be 21.0 nm and 22.5 nm, respectively. The spherical formation of silica coated KFeO2 NPs has been revealed by transmission electron microscope. Presence of silica on KFeO2 NPs has been confirmed by energy dispersive X-ray spectroscope. A small magnetic saturation value of 3.67emu/g has been observed in the vibrating sample magnetometer analysis.

Khanna, Lavanya; Verma, N. K.

2013-06-01

59

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

60

Magnetic properties of cobalt-ferrite nanoparticles embedded in polystyrene resin  

NASA Astrophysics Data System (ADS)

Samples of maghemite and cobalt-ferrite nanoparticles (sizes, 3-10 nm) were prepared by cross-linking sulfonated polystyrene resin with aqueous solutions of (1) FeCl2, (2) 80%FeCl2+20%CoCl2, (3) FeCl3, and (4) 80%FeCl3+20%CoCl2 by volume. Chemical analysis, x-ray powder-diffraction, and 57Fe Mössbauer spectroscopic measurements show that samples 1 and 3 consist of ?-Fe2O3 nanoparticles (sizes, ~10 and 3 nm) and sample 2 and 4 consist of CoxFe3-xO4 nanoparticles (sizes, ~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.

2006-04-01

61

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

PubMed

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

Batoo, Khalid Mujasam

2011-01-01

62

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

63

Microstructural and M?ssbauer 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.

2011-01-01

64

The role of multi-walled carbon nanotubes on the magnetic and reflection loss characteristics of substituted strontium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Substituted strontium ferrite SrFe12-x(Ni0.5Mn0.5Zr)x/2O19/multi-walled carbon nanotubes (MWCNTs) composites were prepared by a sol-gel method. X-ray diffraction patterns confirm the formation of single phase ferrite nanoparticle and nanocomposites of ferrite/carbon nanotubes. Fourier transform infrared spectroscopy demonstrates the existence of functional groups on the surface of carbon nanotubes. Superconducting quantum interference device measurements showed that the values of specific saturation magnetization increases, while coercivity decreases with an increase in substitution content. Zero field cooled magnetization and field cooled magnetization curves display that with an increase in substitution content, the blocking temperature increases. Field emission scanning electron microscopy micrographs demonstrate that ferrite nanoparticles were attached on external surfaces of the carbon nanotubes. The investigation of the microwave absorption indicates that with an addition of carbon nanotubes, the real and imaginary parts of permittivity and reflection loss enhanced. It is found that with increasing the thickness of absorbers, the resonance frequencies shift to lower regime.

Ghasemi, Ali

2013-03-01

65

Embryotoxicity of cobalt ferrite and gold nanoparticles: a first in vitro approach.  

PubMed

Nanoparticles (NPs) are emerging as promising biomedical tools thanks to their peculiar characteristics. Our purpose was to investigate the embryotoxicity of cobalt ferrite and gold NPs through the Embryonic Stem Cell Test (EST). The EST is an in vitro standard assay, which permits to classify substances as strongly, weakly or non-embryotoxic. Due to the particular physical-chemical nature of nanoparticles, we introduced a modification to the standard protocol exposing the Embryonic Stem Cells (ES-D3) to nanoparticles only during the first 5 days of the assay. Moreover, we proposed a method to discriminate and compare the embryotoxicity of the substances within the weakly embryotoxic range. Our ID(50) results permit to classify cobalt ferrite nanoparticles coated with gold and silanes as non-embryotoxic. The remaining nanoparticles have been classified as weakly embryotoxic in this decreasing order: gold salt (HAuCl(4).3H(2)O)>cobalt ferrite salt (CoFe(2)O(4))>cobalt ferrite nanoparticles coated with silanes (Si-CoFe)>gold nanoparticles coated with hyaluronic acid (HA-Au). PMID:20566333

Di Guglielmo, Claudia; López, David Ramos; De Lapuente, Joaquín; Mallafre, Joan Maria Llobet; Suàrez, Miquel Borràs

2010-09-01

66

Preparation of transparent conductors ferroelectric memory materials and ferrites  

DOEpatents

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

67

Preparation of transparent conductors ferroelectric memory materials and ferrites  

DOEpatents

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 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, R.N.; Ginley, D.S.

1998-07-28

68

Structural, Dielectric, FT-IR and Complex Impedance Properties of Cobalt Ferrite Nanoparticles  

NASA Astrophysics Data System (ADS)

Cobalt ferrite nanoparticles having the general formula CoFe2-xCuxO4 (0.0 <= x <= 0.5) were prepared by sol-gel method and characterized by using X-Ray diffraction (XRD), scanning electron microscopy (SEM ), Fourier transform infrared spectroscopy (FTIR), dielectric and impedance spectroscopy measurements. Confirmation of the single phase cubic spinel structure was made by using X-ray diffractometer. Lattice parameter `a' is found to decrease with increasing the doping contents. Debye- Scherer formula was used for finding the particle size and found in the range 30-45 nm. Morphological analysis was made by scanning electron microscopy which shows agglomerated flakes of particles having large pores on the surface. FT-IR spectra show two absorption bands assigned to the tetrahedral and octahedral complexes in the frequency range 400-600 cm-1. The variation of dielectric properties ?', V, tan? with frequency reveals that the dispersion is due to Maxwell-Wagner type of interfacial polarization. Impedance spectroscopy technique has been used to understand the conduction mechanism and to study the effect of grain and grain boundary on the electrical properties of the Cu doped CoFe2O4 ferrites.

Hashim, Mohd.; Alimuddin, Alimuddin; Ali, Sikander; Kumar, Shalendra; Kumar, Ravi

2011-11-01

69

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

70

Microwave Absorption Properties of Mn–Co–Sn Doped Barium Ferrite Nanoparticles  

Microsoft Academic Search

Substituted barium ferrite BaFe9(Mn0.5Co0.5Sn)3\\/2O19 was prepared by sol-gel method. X-ray diffraction (XRD), transmission electron microscope (TEM), AC susceptometer, vibrating sample magnetometer (VSM) and vector network analyzer were used to analyze the structure, static and dynamic magnetic properties of the prepared samples. The prepared ferrite particles possess irregular non spherical shape with a broad size distribution. The substitution was very effective

Ali Ghasemi; Vladimir Sepelak; Xiaoxi Liu; Akimitsu Morisako

2009-01-01

71

Preparation and characterization of honokiol nanoparticles  

Microsoft Academic Search

In this paper, honokiol nanoparticles were prepared by emulsion solvent evaporation method. The prepared honokiol nanoparticles\\u000a were characterized by particle size distribution, morphology, zeta potential and crystallography. Results showed that the\\u000a obtained honokiol nanoparticles at size of 33 nm might be amorphous, and could be well dispersed in water. Due to the great\\u000a dispersibility in water, the obtained honokiol nanoparticles might

Ma Ling Gou; Mei Dai; Xing Yi Li; Xian Huo Wang; Chang Yang Gong; Yao Xie; Ke Wang; Xia Zhao; Zhi Yong Qian; Yu Quan Wei

2008-01-01

72

Mössbauer and magnetic studies in nickel ferrite nanoparticles: Effect of size distribution  

NASA Astrophysics Data System (ADS)

The magnetic properties of nickel ferrite nanoparticles in the form of powders, prepared by the sol-gel process and subjected to different annealing temperatures, were investigated using both static and dynamic measurements namely hysteresis, zero field cooled-field cooled magnetization (ZFC-FC) measurements and Mössbauer spectroscopy. The Transmission Electron Microscopy (TEM) studies reveal particle sizes ˜2-8 nm for the as-prepared particles which increases upto 52 nm with annealing. A bimodal distribution, upto an annealing temperature of 300C was observed. ZFC-FC measurements for the as-prepared samples reveal twin peaks, indicative of the bimodal size distribution. ZFC-FC measurements performed for fields varying from 100 Oe to 3 kOe show a superparamagnetic phase with blocking temperatures between 320 and 85 K. Numerical simulations for the ZFC-FC studies indicate that the signature of the bimodal size distribution can be seen only at very low fields. The variation of coercivity with particle size, as determined from the hysteresis measurements, shows a transition from a single domain to a multi domain state for particle sizes larger than 35 nm. Mössbauer measurements performed at room temperature for the as-prepared sample shows a six finger pattern for the samples with higher particle size and a doublet pattern for the samples with smaller particle size, which is indicative of their superparamagnetic nature.

Malik, Rakesh; Annapoorni, S.; Lamba, Subhalakshmi; Raghavendra Reddy, V.; Gupta, Ajay; Sharma, Parmanand; Inoue, Akihisa

2010-12-01

73

Synthesis of shape controlled ferrite nanoparticles by sonochemical technique.  

PubMed

Synthesis of magnetic iron oxides/ferrites in the nano scale by sonochemical synthesis has become prominent recently. This technique facilitates the synthesis of magnetic particles in the nano scale attributed to the hotspot mechanism arising due to acoustic cavitation induced chemical reaction. Generally volatile organometallic precursor compounds favoring the formation of fully amorphous particles have been used to synthesize various nano magnetic materials. We report here the synthesis of ultrafine, < 10 nm magnetic iron oxide nanoparticles by sonochemical technique starting with a non-volatile precursor iron salt such as iron citrate which seems to favor the formation of semi crystalline/crystalline particles as the reaction takes place either in the interfacial region or in the bulk solution. Mono dispersed, ultra fine, approximately 4 nm spherical shaped magnetic maghemite particles having a saturation magnetization of 58.2 emu/g and coercivity of 118 Oe were obtained at low values of pH, 10 while higher pH, 11-13 favored the formation of elongated, cylindrical, acicular particles with a reduced magnetization. The coercivity was also found to decrease with increasing pH, with it being 118 Oe at pH 10 and 3 Oe at pH 13. When the ultrasound amplitude/intensity was low, 38% heat treatment of the samples at 300 degrees C (at pH 10) was required to make them crystalline, while application of high intensity ultrasound, 50% amplitude served as a single step mechanism for obtaining crystalline maghemite particles. The maghemite particles obtained at a pH of 10 could find applications in information storage media. PMID:19049216

Theerdhala, Sriharsha; Alhat, Devendra; Vitta, Satish; Bahadur, D

2008-08-01

74

Preparation methods of alginate nanoparticles.  

PubMed

This article reviews available methods for the formation of alginate nano-aggregates, nanocapsules and nanospheres. Primarily, alginate nanoparticles are being prepared by two methods. In the "complexation method", complex formation on the interface of an oil droplet is used to form alginate nanocapsules, and complex formation in an aqueous solution is used to form alginate nano-aggregates. In a second method w/o emulsification coupled with gelation of the alginate emulsion droplet can be used to form alginate nanospheres. We review advantages and disadvantages of these methods, and give an overview of the properties of the alginate particles produced with these methods. PMID:24745976

Paques, Jerome P; van der Linden, Erik; van Rijn, Cees J M; Sagis, Leonard M C

2014-07-01

75

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

Microsoft Academic Search

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

Chung-Wen Liu; Cheng-Hsiung Lin; Yen-Pei Fu

2006-01-01

76

Induction of apoptosis in cancer cells by NiZn ferrite nanoparticles through mitochondrial cytochrome C release  

PubMed Central

The long-term objective of the present study was to determine the ability of NiZn ferrite nanoparticles to kill cancer cells. NiZn ferrite nanoparticle suspensions were found to have an average hydrodynamic diameter, polydispersity index, and zeta potential of 254.2 ± 29.8 nm, 0.524 ± 0.013, and ?60 ± 14 mV, respectively. We showed that NiZn ferrite nanoparticles had selective toxicity towards MCF-7, HepG2, and HT29 cells, with a lesser effect on normal MCF 10A cells. The quantity of Bcl-2, Bax, p53, and cytochrome C in the cell lines mentioned above was determined by colorimetric methods in order to clarify the mechanism of action of NiZn ferrite nanoparticles in the killing of cancer cells. Our results indicate that NiZn ferrite nanoparticles promote apoptosis in cancer cells via caspase-3 and caspase-9, downregulation of Bcl-2, and upregulation of Bax and p53, with cytochrome C translocation. There was a concomitant collapse of the mitochondrial membrane potential in these cancer cells when treated with NiZn ferrite nanoparticles. This study shows that NiZn ferrite nanoparticles induce glutathione depletion in cancer cells, which results in increased production of reactive oxygen species and eventually, death of cancer cells.

Al-Qubaisi, Mothanna Sadiq; Rasedee, Abdullah; Flaifel, Moayad Husein; Ahmad, Sahrim Hj; Hussein-Al-Ali, Samer; Hussein, Mohd Zobir; Zainal, Zulkarnain; Alhassan, Fatah H; Taufiq-Yap, Yun H; Eid, Eltayeb EM; Arbab, Ismail Adam; Al-Asbahi, Bandar A; Webster, Thomas J; Zowalaty, Mohamed Ezzat El

2013-01-01

77

Synthesis of NiCuZn ferrite nanoparticles and microwave absorption characterization  

Microsoft Academic Search

This study aimed at the low temperature synthesis of NixCu0.5?xZn0.5Fe2O4 ferrite nanoparticles using the citrate precursor method and the reflectivity characterization of Radar absorbing materials. The NiCuZn phase obtained at 350°C by the Rietveld method showed homogeneous nanoparticle formation. The analysis of particle size and the critical diameter of the domains indicated monodomain formation on nanometric scale. Vibrating sample magnetometry

U. R. Lima; M. C. Nasar; R. S. Nasar; M. C. Rezende; J. H. Araújo; J. F. Oliveira

2008-01-01

78

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

79

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

PubMed

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 degrees 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 degrees 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. PMID:22414887

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

2012-03-30

80

Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel  

PubMed Central

Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network.

van Berkum, Susanne; Dee, Joris T.; Philipse, Albert P.; Erne, Ben H.

2013-01-01

81

Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel.  

PubMed

Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

van Berkum, Susanne; Dee, Joris T; Philipse, Albert P; Erné, Ben H

2013-01-01

82

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

83

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

84

Electron Spin Resonance Studies on the Quantum tunneling in Spinel Ferrite Nanoparticles  

NASA Astrophysics Data System (ADS)

The conversion of ferrimagnets to superparamagnets in spinel ferrite (MOFe2O3) nanoparticles from classical thermally driven transition becomes saliently from quantum tunneling on applying a transverse microwave magnetic field or by implicating of a strong internal anisotropic field at low temperatures. The microwave or crystal anisotropic field that is perpendicular to the Ising axis can destroy the magnetic long-range order as the field exceeds some critical values. Electron spin resonance (ESR) spectrometer, a very sensitive instrument with fast detecting window to explore quantum tunneling for magnetic nanoparticles, was exploited to study this fascinating interplay between thermal and quantum fluctuation in the vicinity of a quantum critical point. We have investigated the effects of various microwave fields and temperature dependence on the dynamic spin susceptibility of several kinds of spinel ferrite nanoparticles.

Hsieh, Chang-Tsun; Lue, Juh-Tzeng

2003-03-01

85

Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Multiferroic bismuth ferrite (BFO) and gadolinium (Gd) doped bismuth ferrite had been synthesized by a sol-gel method. Particle size had been estimated by Transmission electron microscopy (TEM) and found to decrease with Gd doping. We studied the temperature and frequency dependence of impedance and electric modulus and calculated the grain and grain boundary resistance and capacitance of the investigated samples. We observed that electrical activation energy increases for all the doped samples. Optical band gap also increases for the doped samples which can be used in photocatalytic application of BFO.

Mukherjee, A.; Banerjee, M.; Basu, S.; Pal, M.

2014-04-01

86

Synthesis and magnetic properties of CoFe2O4 spinel ferrite nanoparticles doped with lanthanide ions  

Microsoft Academic Search

Lanthanide ions have been doped into cobalt spinel ferrites using an oil-in-water micellar method to form CoLn0.12Fe1.88O4 nanoparticles with Ln=Ce, Sm, Eu, Gd, Dy, or Er. Doping with lanthanide ions (LnIII) modulates the magnetic properties of cobalt spinel ferrite nanoparticles. In particular cases of Gd3+ or Dy3+ ions, a dramatic increase in the blocking temperature and coercivity is observed. Indeed,

Myrtil L. Kahn; Z. John Zhang

2001-01-01

87

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

88

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

89

Galactosylated manganese ferrite nanoparticles for targeted MR imaging of asialoglycoprotein receptor  

NASA Astrophysics Data System (ADS)

Cancer cells can express specific biomarkers, such as cell membrane proteins and signaling factors. Thus, finding biomarkers and delivering diagnostic agents are important in the diagnosis of cancer. In this study, we investigated a biomarker imaging agent for the diagnosis of hepatic cancers. The asialoglycoprotein receptor (ASGPr) was selected as a biomarker for hepatoma cells and the ASGPr-targetable imaging agent bearing a galactosyl group was prepared using manganese ferrite nanoparticles (MFNP) and galactosylgluconic acid. The utility of the ASGPr-targetable imaging agent, galactosylated MFNP (G-MFNP) was assessed by several methods in ASGPr-expressing HepG2 cells as target cells and ASGPr-deficient MCF7 cells. Physical and chemical properties of G-MFNP were examined using Fourier-transform infrared spectroscopy, dynamic light scattering, zeta potential analysis, and transmission electron microscopy. No significant cytotoxicity was observed in either cell line. Targeting ability was assessed using flow cytometry, magnetic resonance imaging, inductively coupled plasma atomic emission spectroscopy, absorbance analysis, dark-field microscopy, Prussian blue staining, and transmission electron microscopy. We demonstrated that G-MFNP target successfully and bind to ASGPr-expressing HepG2 cells specifically. We suggest that these results will be useful in strategies for cancer diagnoses based on magnetic resonance imaging.

Yang, Seung-Hyun; Heo, Dan; Lee, Eugene; Kim, Eunjung; Lim, Eun-Kyung; Lee, Young Han; Haam, Seungjoo; Suh, Jin-Suck; Huh, Yong-Min; Yang, Jaemoon; Park, Sahng Wook

2013-11-01

90

Galactosylated manganese ferrite nanoparticles for targeted MR imaging of asialoglycoprotein receptor.  

PubMed

Cancer cells can express specific biomarkers, such as cell membrane proteins and signaling factors. Thus, finding biomarkers and delivering diagnostic agents are important in the diagnosis of cancer. In this study, we investigated a biomarker imaging agent for the diagnosis of hepatic cancers. The asialoglycoprotein receptor (ASGPr) was selected as a biomarker for hepatoma cells and the ASGPr-targetable imaging agent bearing a galactosyl group was prepared using manganese ferrite nanoparticles (MFNP) and galactosylgluconic acid. The utility of the ASGPr-targetable imaging agent, galactosylated MFNP (G-MFNP) was assessed by several methods in ASGPr-expressing HepG2 cells as target cells and ASGPr-deficient MCF7 cells. Physical and chemical properties of G-MFNP were examined using Fourier-transform infrared spectroscopy, dynamic light scattering, zeta potential analysis, and transmission electron microscopy. No significant cytotoxicity was observed in either cell line. Targeting ability was assessed using flow cytometry, magnetic resonance imaging, inductively coupled plasma atomic emission spectroscopy, absorbance analysis, dark-field microscopy, Prussian blue staining, and transmission electron microscopy. We demonstrated that G-MFNP target successfully and bind to ASGPr-expressing HepG2 cells specifically. We suggest that these results will be useful in strategies for cancer diagnoses based on magnetic resonance imaging. PMID:24192299

Yang, Seung-Hyun; Heo, Dan; Lee, Eugene; Kim, Eunjung; Lim, Eun-Kyung; Lee, Young Han; Haam, Seungjoo; Suh, Jin-Suck; Huh, Yong-Min; Yang, Jaemoon; Park, Sahng Wook

2013-11-29

91

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

92

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

93

Preparation and magnetic properties of composite powders of hollow microspheres coated with barium ferrite  

Microsoft Academic Search

The composites of barium ferrite coated on hollow ceramic microspheres are successfully prepared using sol–gel combustion method. The crystal structure and magnetic properties with different weight ratio of hollow microspheres in the composite are studied with X-ray diffraction (XRD), differential scanning calorimetry (DSC)\\/DTA and vibrating sample magnetometry (VSM). The results show that the composites are composed of barium ferrite and

Guohong Mu; Xifeng Pan; Haigen Shen; Mingyuan Gu

2007-01-01

94

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

95

Mössbauer spectroscopy, magnetic characteristics, and reflection loss analysis of nickel-strontium substituted cobalt ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

In current research work, Co1-xNix/2Srx/2Fe2O4 (x = 0-1 in a step of 0.2) ferrite nanoparticles were synthesized by a sol-gel method. According to the evolution in the subspectral areas obtained from Mössbauer spectroscopy, it was found that the relaxing iron belongs mostly to the site B, since the Mössbauer fraction of site A does not vary appreciably. With an increase in Ni-Sr substitution contents in cobalt ferrite, the coercivity and saturation of magnetization decrease. Variation of reflection loss versus frequency in microwave X-band demonstrates that the reflection peak shifts to lower frequency by adding substituted cations and the synthesized nanoparticles can be considered for application in electromagnetic wave absorber technology.

Ghasemi, Ali; Paesano, Andrea; Cerqueira Machado, Carla Fabiana; Shirsath, Sagar E.; Liu, Xiaoxi; Morisako, Akimitsu

2014-05-01

96

An integrated study of thermal treatment effects on the microstructure and magnetic properties of Zn-ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

The evolution of the magnetic state, crystal structure and microstructure parameters of nanocrystalline zinc-ferrite, tuned by thermal annealing of ˜4 nm nanoparticles, was systematically studied by complementary characterization methods. Structural analysis of neutron and synchrotron x-ray radiation data revealed a mixed cation distribution in the nanoparticle samples, with the degree of inversion systematically decreasing from 0.25 in an as-prepared nanocrystalline sample to a non-inverted spinel structure with a normal cation distribution in the bulk counterpart. The results of DC magnetization and Mössbauer spectroscopy experiments indicated a superparamagnetic relaxation in ˜4 nm nanoparticles, albeit with different freezing temperatures Tf of 27.5 K and 46 K, respectively. The quadrupole splitting parameter decreases with the annealing temperature due to cation redistribution between the tetrahedral and octahedral sites of the spinel structure and the associated defects. DC magnetization measurements indicated the existence of significant interparticle interactions among nanoparticles (‘superspins’). Additional confirmation for the presence of interparticle interactions was found from the fit of the Tf(H) dependence to the AT line, from which a value of the anisotropy constant of Keff = 5.6 × 105 erg cm-3 was deduced. Further evidence for strong interparticle interactions was found from AC susceptibility measurements, where the frequency dependence of the freezing temperature Tf(f) was satisfactory described by both Vogel-Fulcher and dynamic scaling theory, both applicable for interacting systems. The parameters obtained from these fits suggest collective freezing of magnetic moments at Tf.

Antic, Bratislav; Perovic, Marija; Kremenovic, Aleksandar; Blanusa, Jovan; Spasojevic, Vojislav; Vulic, Predrag; Bessais, Lotfi; Bozin, Emil S.

2013-02-01

97

Production of Co-Ti ferrite nanoparticles for use as agents in hyperthermia treatment  

Microsoft Academic Search

Co-Ti ferrite (Co1+xTixFe2-2xO4, 0.2 <= x <= 0.5) nanoparticles with average diameters ranging from 6 to 12 nm were produced by using our novel wet chemical method. The crystal structures and magnetic properties of the obtained samples were investigated by X-ray diffraction and superconducting quantum interference device (SQUID) magnetometer measurements. DC magnetization measurements showed that the coercive force Hc and

Daiki Shigeoka; Hikaru Katayanagi; Yuki Moro; Shinji Kimura; Toshiyuki Mashino; Yuko Ichiyanagi

2010-01-01

98

Preparation of electrophoretic nanoparticles for electronic paper.  

PubMed

As an electronic alternative for printed media, the E-paper has ultralow power consumption, reduced eyestrain, high contrast ratio. Electrophoretic displays are one of the most promising E-paper technologies, which are now widely used in consumer products. The properties of the electrophoretic display are mainly determined by the composition, size, light scattering properties, and density of the electrophoretic nanoparticles. First, we introduce the preparation of white and black electrophoretic nanoparticles, because the monochrome E-paper has achieved commercial success. Then the structure and properties of color electrophoretic nanoparticles for color E-paper products are discussed. In addition, the enhanced and novel electrophoretic nanoparticles are now propelling the development of next-generation E-paper with new applications. Finally, the active area of the preparation of electrophoretic nanoparticles is highlighted in terms of the development of future E-paper. PMID:24749445

Meng, Xianwei; Qiang, Li; Wei, Jianfei; Shi, Haitang

2014-02-01

99

A LOW TEMPERATURE PATH TO THE PREPARATION OF CoFe2O4 FERRITE  

Microsoft Academic Search

Ultrafine cobalt ferrite has been prepared by the decomposition of cobalt oxalate-hydrazinate complex, which is used as precursor. The preparation and thermal decomposition of the precursor have been studied using chemical, thermal, and infrared techniques. The precursor decomposes at low temperatures with the effusion of large amounts of gases. The coordination compounds used as chemical precursors have to include, ligands,

E. Chirtop; I. Mitova; R. M. Ion; M. Iliescu

100

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

101

Effects of magnetic cobalt ferrite nanoparticles on biological and artificial lipid membranes  

PubMed Central

Background The purpose of this work is to provide experimental evidence on the interactions of suspended nanoparticles with artificial or biological membranes and to assess the possibility of suspended nanoparticles interacting with the lipid component of biological membranes. Methods 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid vesicles and human red blood cells were incubated in suspensions of magnetic bare cobalt ferrite (CoFe2O4) or citric acid (CA)-adsorbed CoFe2O4 nanoparticles dispersed in phosphate-buffered saline and glucose solution. The stability of POPC giant unilamellar vesicles after incubation in the tested nanoparticle suspensions was assessed by phase-contrast light microscopy and analyzed with computer-aided imaging. Structural changes in the POPC multilamellar vesicles were assessed by small angle X-ray scattering, and the shape transformation of red blood cells after incubation in tested suspensions of nanoparticles was observed using scanning electron microscopy and sedimentation, agglutination, and hemolysis assays. Results Artificial lipid membranes were disturbed more by CA-adsorbed CoFe2O4 nanoparticle suspensions than by bare CoFe2O4 nanoparticle suspensions. CA-adsorbed CoFe2O4-CA nanoparticles caused more significant shape transformation in red blood cells than bare CoFe2O4 nanoparticles. Conclusion Consistent with their smaller sized agglomerates, CA-adsorbed CoFe2O4 nanoparticles demonstrate more pronounced effects on artificial and biological membranes. Larger agglomerates of nanoparticles were confirmed to be reactive against lipid membranes and thus not acceptable for use with red blood cells. This finding is significant with respect to the efficient and safe application of nanoparticles as medicinal agents.

Drasler, Barbara; Drobne, Damjana; Novak, Sara; Valant, Janez; Boljte, Sabina; Otrin, Lado; Rappolt, Michael; Sartori, Barbara; Iglic, Ales; Kralj-Iglic, Veronika; Sustar, Vid; Makovec, Darko; Gyergyek, Saso; Hocevar, Matej; Godec, Matjaz; Zupanc, Jernej

2014-01-01

102

Control of the Size of Cobalt Ferrite Nanoparticles : Synthesis and Properties  

Microsoft Academic Search

The preparation of a fluid of cobalt ferrite particles having a size varying from 2 to 5nm is described. This bas been achieved by using functionalized surfactants. The size of cobalt femte particles decreases when the total reactant concentration decreases. The magnetic properties are described with magnetization curves and \\

M. P. Pileni; N. Moumen; J. F. Hochepied; P. Bonville; P. Veillet

1997-01-01

103

Rod-shaped polyaniline barium ferrite nanocomposite: preparation, characterization and properties  

NASA Astrophysics Data System (ADS)

Rod-shaped polyaniline (PANI)-barium ferrite nanocomposite was synthesized by in situ polymerization of aniline in the presence of BaFe12O19 nanoparticles with diameters of 60-80 nm. The structure, morphology and properties of the nanocomposite were measured using powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. Different ferrite/PANI ratios were selected in order to study magnetic and conductive properties. The results indicated that there were some interactions between PANI chains and ferrite particles. The saturation magnetization and the coercivity varied with the ferrite content. The conductivity at room temperature decreased from 43.35 to 6.9 × 10-2 S cm-1 when the ferrite content changed from 0 to 50 wt%. The composite has excellent electromagnetic parameters which indicates potential application in high performance adsorbing materials in broadband and high frequency ranges. The polymerization mechanism and interactions in the nanocomposites were also studied.

Li, Yuanxun; Zhang, Huaiwu; Liu, Yingli; Wen, Qiye; Li, Jie

2008-03-01

104

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

105

Magnetic and structural studies of nickel-substituted cobalt ferrite nanoparticles, synthesized by the sol-gel method  

NASA Astrophysics Data System (ADS)

In this study Ni substituted cobalt ferrite nanoparticles (NixCo1-xFe2O4 where x=0.1, 0.3, 0.5, 0.7 and 0.9) were prepared by the sol-gel method. Phase identification of the samples was performed by the X-ray diffraction (XRD) method and the mean crystallite sizes of the samples were obtained using Scherrer's formula. The results show that a minimum calcining temperature of 500 °C is required to obtain single phase spinel structures for all the samples. It was observed that the lattice parameter of the samples decreases from 8.350 to 8.300 Å with increasing Ni content. Morphology of the samples was investigated by a field emission scanning electron microscope (FESEM). Also mean particle sizes of the samples were obtained from FESEM images and there no relation between particle size and Ni content was found. Magnetic measurements were carried out on the cold pressed samples and the results show that saturation magnetization decreases as x increases. Curie temperatures of the samples were determined and the results show that by increasing x values their Curie temperatures increase. This increase was explained based on the change in superexchange interactions between magnetic ions by substitution of Ni ions in Co ferrite. Also the coercive forces of the samples decreased with increasing x values which was explained by the changes in magnetocrystalline anisotropy.

Mozaffari, M.; Amighian, J.; Darsheshdar, E.

2014-01-01

106

Online monitoring of cell metabolism to assess the toxicity of nanoparticles: the case of cobalt ferrite.  

PubMed

Different in vitro assays are successfully used to determine the relative cytotoxicity of a broad range of compounds. Nevertheless, different research groups have pointed out the difficulty in using the same tests to assess the toxicity of nanoparticles (NPs). In this study, we evaluated the possible use of a microphysiometer, Bionas 2500 analyzing system Bionas GmbH®, to detect in real time changes in cell metabolisms linked to NPs exposure. We focused our work on response changes of fibroblast cultures linked to exposure by cobalt ferrite NPs and compared the results to conventional in vitro assays. The measurements with the microphysiometer showed a cobalt ferrite cytotoxic effect, confirmed by the Colony Forming Efficiency assay. In conclusion, this work demonstrated that the measurement of metabolic parameters with a microphysiometer is a promising method to assess the toxicity of NPs and offers the advantage to follow on-line the cell metabolic changes. PMID:21495878

Mariani, Valentina; Ponti, Jessica; Giudetti, Guido; Broggi, Francesca; Marmorato, Patrick; Gioria, Sabrina; Franchini, Fabio; Rauscher, Hubert; Rossi, François

2012-05-01

107

Magnetic and Mössbauer spectroscopic studies of NiZn ferrite nanoparticles synthesized by a combustion method  

NASA Astrophysics Data System (ADS)

The properties of nanocrystalline Ni0.5Zn0.5Fe2O4 synthesized by an auto-combustion method have been investigated by magnetic measurements and Mössbauer spectroscopy. The as-synthesized single phase nanosized ferrite powder is annealed at different temperatures in the range 673 1,273 K to obtain nanoparticles of different sizes. The powders are characterized by powder X-ray diffraction, vibrating sample magnetometer, transmission electron microscopy and Mössbauer spectroscopy. The as-synthesized powder with average particle size of ~9 nm is superparamagnetic. Magnetic transition temperature increases up to 665 K for the nanosized powder as compared to the transition temperature of 548 K for the bulk ferrite. This has been confirmed as due to the abnormal cation distribution, as evidenced from room temperature Mössbauer spectroscopic studies.

Sreeja, V.; Vijayanand, S.; Deka, S.; Joy, P. A.

2008-04-01

108

Effects of pH and citric acid content on the structure and magnetic properties of MnZn ferrite nanoparticles synthesized by a sol-gel autocombustion method  

NASA Astrophysics Data System (ADS)

MnZn ferrite nanoparticles have been synthesized by a sol-gel autocombustion technique with different pHs of 0, 5 and 7 and different citric acid to metal nitrate (CA/MN) molar ratios of 0.25, 0.5 and 1. The crystallite size, microstructure and magnetic properties were studied using X-ray diffraction, scanning electron microscopy and vibrating sample magnetometry methods. The results showed that the single phase MnZn ferrite could be achieved directly without any post-calcination using pH of 7 and CA/MN molar ratio of 0.5. MnZn ferrite nanoparticles prepared by pH=7 and CA/MN=0.5 with the crystallite size of 39 nm exhibited saturation magnetization of 20.9 emu/g and coercivity of 44 Oe.

Seyyed Ebrahimi, S. A.; Masoudpanah, S. M.

2014-05-01

109

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

110

A simple process for ferrite film preparation from one solution without using hazardous oxidizing agent  

NASA Astrophysics Data System (ADS)

A process for ferrite film preparation using an aqueous solution was developed and named as ``one solution spray technique'' (OSST). Highly crystallized spinel ferrite films can be prepared by spraying only one solution at a very low temperature of 90 °C without any postannealing. In contrast to the conventional spray technique (CST), two solutions (reaction solution and an oxidizing solution containing pH buffer) were independently sprayed. In OSST, reaction solution containing a mixture of FeCl2, CH3COOK, and urea was used. The Fe3O4 films prepared by OSST exhibited a real permeability of ?'=35 and a very high resonance frequency of fr=1.25 GHz, which was superior to that for films prepared by CST (fr=850 MHz). The ?''×f spectra, which are proportional to the noise suppression effect of the films, proved that the films prepared by this technique have suitable properties to be used as conducted noise suppressors in the gigahertz range.

Subramani, A. K.; Matsushita, N.; Watanabe, T.; Tada, M.; Abe, M.; Yoshimura, M.

2007-05-01

111

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 (50-70 nm) have been synthesized via emulsion polymerization. The complex permittivity, permeability, and microwave absorption properties of the composite were studied in the 12.4-18 GHz (Ku band) frequency range. The composite has shown high shielding effectiveness due to absorption (SEA) of 28.9 dB (~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

112

Faraday rotation of cobalt ferrite nanoparticle polymer composite films at cryogenic temperatures.  

PubMed

This paper investigates the behavior of the Verdet constant for cobalt ferrite (CoFe2O4) nanoparticles polymer composite films at low temperatures using a 532 nm laser source. An experimental setup for Faraday rotation (FR) at low temperatures is introduced and FRs were measured at various temperatures. Verdet constants were deduced from the paramagnetic model for terbium gallium garnet glass where ?4× improvement was observed at 40° K for CoFe2O4 composite film. PMID:24787165

Demir, Veysi; Gangopadhyay, Palash; Norwood, Robert A; Peyghambarian, Nasser

2014-04-01

113

Preparation and electrical properties of dense micro-cermets made of nickel ferrite and metallic copper  

NASA Astrophysics Data System (ADS)

Dense micro-cermets made of nickel ferrites and copper micrometric particles were obtained from partial reduction under hydrogenated atmosphere at 350 °C of mixed copper nickel ferrites, and sintering in nitrogen at 980 °C. The small copper particles are homogeneous in size and well dispersed in the spinel oxide matrix. No exudation of copper metal was observed after sintering. The micro-cermets prepared are semi-conducting materials with electrical conductivity lying from 44 to 130 S/cm at 980 °C. Their overall characteristics make them interesting for inert anodes dedicated to aluminium electrolysis in melted cryolite.

Baco-Carles, Valérie; Pasquet, Isabelle; Laurent, Véronique; Gabriel, Armand; Tailhades, Philippe

2009-08-01

114

Study of the thermal stability of nanoparticle distributions in an oxide dispersion strengthened (ODS) ferritic alloys  

NASA Astrophysics Data System (ADS)

Oxide dispersion strengthened (ODS) ferritic alloys have a vast applicability due to their excellent mechanical resistance at high temperature. The precipitate dispersion of the nanoparticles in the matrix has a great effect on the creep properties of the material; in order to study the kinetics of precipitation of Y2Ti2O7 nanoparticles in Fe-14Cr1W ODS alloy, annealing experiments were taken at different temperatures (1050 °C-1400 °C) and for different times (0.5-10 h), then these samples were characterized by the small-angle neutron scattering technique (SANS) under magnetic field and TEM investigations and microhardness measurements were performed to gather nanoscopic information about the dispersed oxide particles size.

Zhong, S. Y.; Ribis, J.; Klosek, V.; de Carlan, Y.; Lochet, N.; Ji, V.; Mathon, M. H.

2012-09-01

115

Synthesis and optical properties of nickel zinc ferrite nanoparticles grown within mesoporous silica template  

NASA Astrophysics Data System (ADS)

Nanocomposite (NC) of nickel zinc ferrite (NZF) in mesoporous silica template (KIT-6) was synthesized and characterized in this work. Impregnation procedure was used to synthesize NZF nanoparticles within the pores of KIT-6. The samples were characterized by transmission electron microscopy (TEM), FTIR and UV-Vis absorption studies and room temperature (RT) photoluminescence (PL) measurement. The morphology from Transmission Electron Microscopy of the NC showed the ordered porous structure of KIT-6 remained undistorted even after the incorporation of NZF nanoparticles within its pores. From UV-Vis spectra of the NC, a blue shift in the absorption band due to quantum confinement effect was found. Due to some defects present a broad PL peak centred at 490 nm after excitation at 428 nm of the NC was observed.

Banerjee, Shilpi; Chakravorty, Dipankar

2012-06-01

116

Mössbauer characterization of calcium-ferrite oxides prepared by calcining Fe2O3 and CaO  

NASA Astrophysics Data System (ADS)

Calcium ferrite oxides were prepared by calcining a mixture powder of iron- and calcium oxide. The 57Fe-Mössbauer spectra of the calcium ferrites oxides were measured, revealing that the products should be Ca2Fe2O5 and CaFe2O4, the ratio of which was dependent of the Fe/Ca atomic ratio of the mixture powder.

Hirabayashi, Daisuke; Sakai, Yoichi; Yoshikawa, Takeshi; Mochizuki, Kazuhiro; Kojima, Yoshihiro; Suzuki, Kenzi; Ohshita, Kazumasa; Watanabe, Yasuo

117

Mössbauer characterization of calcium ferrite oxides prepared by calcining Fe2O3 and CaO  

NASA Astrophysics Data System (ADS)

Calcium ferrite oxides were prepared by calcining a mixture powder of iron- and calcium oxide. The 57Fe-Mössbauer spectra of the calcium ferrites oxides were measured, revealing that the products should be Ca2Fe2O5 and CaFe2O4, the ratio of which was dependent of the Fe/Ca atomic ratio of the mixture powder.

Hirabayashi, Daisuke; Sakai, Yoichi; Yoshikawa, Takeshi; Mochizuki, Kazuhiro; Kojima, Yoshihiro; Suzuki, Kenzi; Ohshita, Kazumasa; Watanabe, Yasuo

2006-01-01

118

Manganese ferrite-based nanoparticles induce ex vivo, but not in vivo, cardiovascular effects  

PubMed Central

Magnetic nanoparticles (MNPs) have been used for various biomedical applications. Importantly, manganese ferrite-based nanoparticles have useful magnetic resonance imaging characteristics and potential for hyperthermia treatment, but their effects in the cardiovascular system are poorly reported. Thus, the objectives of this study were to determine the cardiovascular effects of three different types of manganese ferrite-based magnetic nanoparticles: citrate-coated (CiMNPs); tripolyphosphate-coated (PhMNPs); and bare magnetic nanoparticles (BaMNPs). The samples were characterized by vibrating sample magnetometer, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. The direct effects of the MNPs on cardiac contractility were evaluated in isolated perfused rat hearts. The CiMNPs, but not PhMNPs and BaMNPs, induced a transient decrease in the left ventricular end-systolic pressure. The PhMNPs and BaMNPs, but not CiMNPs, induced an increase in left ventricular end-diastolic pressure, which resulted in a decrease in a left ventricular end developed pressure. Indeed, PhMNPs and BaMNPs also caused a decrease in the maximal rate of left ventricular pressure rise (+dP/dt) and maximal rate of left ventricular pressure decline (?dP/dt). The three MNPs studied induced an increase in the perfusion pressure of isolated hearts. BaMNPs, but not PhMNPs or CiMNPs, induced a slight vasorelaxant effect in the isolated aortic rings. None of the MNPs were able to change heart rate or arterial blood pressure in conscious rats. In summary, although the MNPs were able to induce effects ex vivo, no significant changes were observed in vivo. Thus, given the proper dosages, these MNPs should be considered for possible therapeutic applications.

Nunes, Allancer DC; Ramalho, Laylla S; Souza, Alvaro PS; Mendes, Elizabeth P; Colugnati, Diego B; Zufelato, Nicholas; Sousa, Marcelo H; Bakuzis, Andris F; Castro, Carlos H

2014-01-01

119

Synthesis of MPTS-modified cobalt ferrite nanoparticles and their adsorption properties in relation to Au(III).  

PubMed

Cobalt ferrite magnetic nanoparticles (Co-MNP) were prepared by a co-precipitation method and subsequently coated with (3-mercaptopropyl)trimethoxysilane (MPTS) for the extraction and recovery of Au(III) from aqueous chloride solutions. Physical characterization of the MPTS-modified particles (Co-MPTS) was performed using FT-IR, TGA, and SEM. Results from FT-IR confirmed that MPTS was present on the surface of the magnetic nanoparticles. The amount of MPTS was 0.36 mmol g(-1) of Co-MPTS, obtained by elemental analysis. SEM images revealed aggregates composed of nanocrystalline Co-MPTS particles. The extraction efficiency as a function of the pH, contact time, and initial Au(III) concentration was evaluated. The modified particles showed maximum adsorption in the pH range from 1.0 to 4.0. The adsorption behavior of Co-MPTS toward Au(III) followed a Langmuir isotherm and the maximum adsorption capacity was found to be 120.5 mg g(-1). The stability of the modified materials was improved as compared to that of bare Co-MNP. The subsequent desorption of gold could be achieved by using acidified thiourea solution; the highest gold recovery reached 85%. PMID:19647836

Kraus, Andrea; Jainae, Kunawoot; Unob, Fuangfa; Sukpirom, Nipaka

2009-10-15

120

Enhanced antibactericidal function of W 4+-doped titania-coated nickel ferrite composite nanoparticles: A biomaterial system  

Microsoft Academic Search

The study demonstrates a distinct enhancement of antimicrobial activity of W4+-doped titania that is coated on nickel ferrite nanoparticles in comparison to undoped titania. The composite nanoparticles were synthesized by uniquely combining reverse micelle and chemical hydrolysis synthesis methods [Rana S, Rawat J, Misra RDK, Acta Biomater 2005;1:691]. The superior antimicrobial activity of W4+-doped titania is related to the inhibition

B. K. Sunkara; R. D. K. Misra

2008-01-01

121

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

122

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), ~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 (~12 emu/g).

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

2005-05-01

123

Synthesis and characterization of zinc ferrite nanoparticles by a thermal treatment method  

NASA Astrophysics Data System (ADS)

Crystalline zinc ferrite (ZnFe 2O 4) was prepared by the thermal treatment method, followed by calcination at various temperatures from 723 to 873 K. Poly (vinyl pyrrolidon) (PVP) was used as a capping agent to stabilize the particles and prevent them from agglomeration. The characterization studies were conducted by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average particle sizes of 17-31 nm were obtained by TEM images, which were in good agreement with the XRD results. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of metal oxide bands at all temperatures and the absence of organic bands at 873 K. The magnetic properties were demonstrated by a vibrating sample magnetometer (VSM), which displayed super paramagnetic behaviors for the calcined samples. The present study also substantiated that, in ferrites, the values of the quantities that were acquired by VSM, such as the saturation magnetization and coercivity field, are primarily dependent on the methods of preparation of the ferrites. Electron paramagnetic resonance (EPR) spectroscopy showed the existence of unpaired electrons and measured the peak-to-peak line width ( ?H), the resonant magnetic field ( Hr), and the g-factor values.

Naseri, Mahmoud Goodarz; Saion, Elias B.; Hashim, Mansor; Shaari, Abdul Halim; Ahangar, Hossein Abasstabar

124

Productive encounter: molecularly imprinted nanoparticles prepared using magnetic templates.  

PubMed

Synthesis of core-shell nanoparticles by surface initiated reversible addition fragmentation chain transfer polymerization in presence of a chiral template conjugated to magnetic nanoparticles is reported. The approach leads to imprinted nanoparticles featuring enantioselectivity and enhanced affinity compared to nanoparticles prepared using free template. PMID:24983025

Berghaus, Melanie; Mohammadi, Reza; Sellergren, Börje

2014-07-15

125

Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles  

PubMed Central

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.

2011-01-01

126

Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles.  

PubMed

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. PMID:21774807

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

2011-01-01

127

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

128

Preparation and characterization of manganese ferrite-based magnetic liposomes for hyperthermia treatment of cancer  

Microsoft Academic Search

Comparative evaluation of two different methods of magnetic liposomes preparation, namely thin film hydration (TFH) and double emulsion (DE) with different molar ratios of egg-phosphatidyl choline (egg-PC) and cholesterol using lauric acid coated manganese ferrite-based aqueous magnetic fluid, is reported. TFH was found to be a better method of encapsulation and TFH 2:1 (egg-PC: cholesterol) magnetic liposomes showed the highest

Pallab Pradhan; Jyotsnendu Giri; Rinti Banerjee; Jayesh Bellare; Dhirendra Bahadur

2007-01-01

129

Gas sensing properties of magnesium ferrite prepared by co-precipitation method  

Microsoft Academic Search

Polycrystalline magnesium ferrite (MgFe2O4) was prepared by the co-precipitation method. The synthesized compound was characterized for their phase and morphology by X-ray diffraction and scanning electron microscopy, respectively. Conductance responses of the (MgFe2O4) were measured towards gases like hydrogen sulfide (H2S), liquefied petroleum gas (LPG), ethanol vapors (C2H5OH), SOx, H2, NOx, NH3, methanol, acetone and petrol. The gas sensing characterstics

P. P. Hankare; S. D. Jadhav; U. B. Sankpal; R. P. Patil; R. Sasikala; I. S. Mulla

2009-01-01

130

Microwave absorption of nanosized barium ferrite particles prepared using high-energy ball milling  

Microsoft Academic Search

The M-type hexagonal barium ferrite powder was obtained after the calcination of precursor, which was prepared with self-propagating high-temperature synthesis. Using high-energy ball milling, the powder size was turned into nanoscale. X-ray diffraction (XRD), transmission electron microscope (TEM) and vector network analyzer were used to analyse its structure and microwave absorption property. The results indicate that the nanoscale milled barium

Jianxun Qiu; Haigen Shen; Mingyuan Gu

2005-01-01

131

Extracting indium and preparing ferric oxide for soft magnetic ferrite materials from zinc calcine reduction lixivium  

Microsoft Academic Search

A hydrometallurgical process for indium extraction and ferric oxide powder preparation for soft magnetic ferrite material\\u000a was developed. Using reduction lixivium from high-acid reductive leaching of zinc oxide calcine as raw solution, copper and\\u000a indium were firstly recovered by iron powder cementation and neutralization. The recovery ratios of Cu and In are 99% and\\u000a 95%, respectively. Some harmful impurities that

Jing He; Mo-tang Tang; Cun Zhou; Sheng-nan Wu; Yong-ming Chen; Tao Wang; Ling Huang

2011-01-01

132

Synthesis and magnetic properties of CoFe2O4 spinel ferrite nanoparticles doped with lanthanide ions  

NASA Astrophysics Data System (ADS)

Lanthanide ions have been doped into cobalt spinel ferrites using an oil-in-water micellar method to form CoLn0.12Fe1.88O4 nanoparticles with Ln=Ce, Sm, Eu, Gd, Dy, or Er. Doping with lanthanide ions (LnIII) modulates the magnetic properties of cobalt spinel ferrite nanoparticles. In particular cases of Gd3+ or Dy3+ ions, a dramatic increase in the blocking temperature and coercivity is observed. Indeed, the introduction of only 4% of Gd3+ ions increases the blocking temperature ~100 K and the coercivity 60%. Initial studies on the magnetic properties of these doped nanoparticles clearly demonstrate that the relationship between the modulation of magnetic properties and the nature of doped LnIII ions is interesting but very complex.

Kahn, Myrtil L.; Zhang, Z. John

2001-06-01

133

Synthesis and characterization of CoFe2O4 ferrite nanoparticles obtained by an electrochemical method.  

PubMed

Uniform size cobalt ferrite nanoparticles have been synthesized in one step using an electrochemical technique. Synthesis parameters such as the current density, temperature and stirring were optimized to produce pure cobalt ferrite. The nanoparticles have been investigated by means of magnetic measurements, Mössbauer spectroscopy, x-ray powder diffraction and transmission electron microscopy. The average size of the electrosynthesized samples was controlled by the synthesis parameters and this showed a rather narrow size distribution. The x-ray analysis shows that the CoFe(2)O(4) obtained presents a totally inverse spinel structure. The magnetic properties of the stoichiometric nanoparticles show ferromagnetic behavior at room temperature with a coercivity up to 6386 Oe and a saturation magnetization of 85 emu g(-1). PMID:22894928

Mazarío, E; Herrasti, P; Morales, M P; Menéndez, N

2012-09-01

134

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

135

Curcumin nanoparticles: preparation, characterization, and antimicrobial study.  

PubMed

Curcumin is a highly potent, nontoxic, bioactive agent found in turmeric and has been known for centuries as a household remedy to many ailments. The only disadvantage that it suffers is of low aqueous solubility and poor bioavailability. The aim of the present study was to develop a method for the preparation of nanoparticles of curcumin with a view to improve its aqueous-phase solubility and examine the effect on its antimicrobial properties. Nanoparticles of curcumin (nanocurcumin) were prepared by a process based on a wet-milling technique and were found to have a narrow particle size distribution in the range of 2-40 nm. Unlike curcumin, nanocurcumin was found to be freely dispersible in water in the absence of any surfactants. The chemical structure of nanocurcumin was the same as that of curcumin, and there was no modification during nanoparticle preparation. A minimum inhibitory concentration of nanocurcumin was determined for a variety of bacterial and fungal strains and was compared to that of curcumin. It was found that the aqueous dispersion of nanocurcumin was much more effective than curcumin against Staphylococcus aureus , Bacillus subtilis , Escherichia coli , Pseudomonas aeruginosa , Penicillium notatum , and Aspergillus niger . The results demonstrated that the water solubility and antimicrobial activity of curcumin markedly improved by particle size reduction up to the nano range. For the selected microorganisms, the activity of nanocurcumin was more pronounced against Gram-positive bacteria than Gram-negative bacteria. Furthermore, its antibacterial activity was much better than antifungal activity. The mechanism of antibacterial action of curcumin nanoparticles was investigated by transmission electron micrograph (TEM) analysis, which revealed that these particles entered inside the bacterial cell by completely breaking the cell wall, leading to cell death. PMID:21322563

Bhawana; Basniwal, Rupesh Kumar; Buttar, Harpreet Singh; Jain, V K; Jain, Nidhi

2011-03-01

136

Electron spin resonance studies on quantum tunneling in spinel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

The electron spin resonance (ESR) spectrometer, a very sensitive instrument with fast detecting window to explore quantum phase transitions for magnetic nanoparticles, was exploited to study the fascinating interplay between thermal and quantum fluctuations in the vicinity of a quantum critical point. We have measured ESR in ferrofluid samples containing nanosize particles of Fe2O3. The evolution of the ESR spectrum with temperature suggests that quantum tunneling of spins occurs in single domain magnetic particles in the low temperature regime. The effects of various microwave fields, particle sizes, and temperatures on the magnetic states of single domain spinel ferrite nanoparticles are investigated. We can consistently explain experimental data assuming that, as the temperature decreases, the spectrum changes from superparamagnetic (SPR) to blocked SPR and finally evolves quantum superparamagnetic behaviour as the temperature lowers down further. A nanoparticle system of a highly anisotropic magnetic material can be qualitatively specified by a simple quantum spin model, or by the Heisenberg model with strong easy-plane anisotropy.

Hsieh, C. T.; Lue, J. T.

2003-10-01

137

Distinguishing magnetic blocking and surface spin-glass freezing in nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Nickel ferrite nanoparticles dispersed in SiO2 matrix have been synthesized by sol-gel method. Structural analysis has been performed by using x-ray diffraction and transmission electron microscopy. Magnetic properties have been investigated by using superconducting quantum interference device magnetometry. In addition to the average blocking temperature peak at TB=120 K measured by a zero field cooled temperature scan of the dc susceptibility, an additional hump near 15 K is observed. Temperature dependent out-of-phase ac susceptibility shows the same features: one broad peak at high temperature and a second narrow peak at low temperature. The high temperature peak corresponds to magnetic blocking of individual nanoparticles, while the low temperature peak is attributed to surface spin-glass freezing which becomes dominant for decreasing particle diameter. To prove the dynamics of the spin (dis)order in both regimes of freezing and blocking, the frequency dependent ac susceptibility is investigated under a biasing dc field. The frequency shift in the ``frozen'' low-temperature ac susceptibility peak is fitted to a dynamic scaling law with a critical exponent zv=7.5, which indicates a spin-glass phase. Exchange bias is turned on at low temperature which signifies the existence of a strong core-shell interaction. Aging and memory effects are further unique fingerprints of a spin-glass freezing on the surface of isolated magnetic nanoparticles.

Nadeem, K.; Krenn, H.; Traussing, T.; Letofsky-Papst, I.

2011-01-01

138

Enhanced magnetic properties of Dy3+ substituted Ni-Cu-Zn ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Dy3+ substituted Ni-Cu-Zn (Ni0.4Cu0.4Zn0.2DyxFe2-xO4) ferrite nanoparticles were obtained at 600 °C by synthesizing sol-gel auto-combustion method, and they exhibit a particle size of 12-21 nm. X-ray diffraction patterns confirm the presence of secondary phase of DyFeO3 and Fe2O3 for the Dy3+ substituted samples. Ni-Cu-Zn ferries doped with Dy3+ possess better grain structure and growth than that of pure Ni-Cu-Zn ferrite. The saturation magnetization increases remarkably up to 81 emu/g with increasing the Dy3+ ions. The increased saturation magnetization related to increased exchange interactions between Fe-Fe ions and also with increased particle size. Blocking temperature was found to decrease with increasing Dy3+ substitution. An enhancement in initial permeability and Curie temperature was observed with Dy3+ substitution.

Shirsath, Sagar E.; Kadam, R. H.; Patange, S. M.; Mane, M. L.; Ghasemi, Ali; Morisako, Akimitsu

2012-01-01

139

Cryocrystallization during preparation of ferrites by cryochemical technology  

Microsoft Academic Search

Characteristics are considered for material prepared by cryochemical technology connected with its thermal conductivity and\\u000a heat capacity, i.e., heat penetration coefficient. It is concluded that for rapidly occurring solidification it is desirable\\u000a to use in calculations not the temperature of the cooling medium or substrate, but the contact temperature of interacting\\u000a media, and this increases calculation accuracy. The effect of

V. I. Gulevich

2007-01-01

140

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

141

Fabrication of a glucose biosensor based on citric acid assisted cobalt ferrite magnetic nanoparticles.  

PubMed

A novel and practical glucose biosensor was fabricated with immobilization of Glucose oxidase (GOx) enzyme on the surface of citric acid (CA) assisted cobalt ferrite (CF) magnetic nanoparticles (MNPs). This innovative sensor was constructed with glassy carbon electrode which is represented as (GOx)/CA-CF/(GCE). An explicit high negative zeta potential value (-22.4 mV at pH 7.0) was observed on the surface of CA-CF MNPs. Our sensor works on the principle of detection of H2O2 which is produced by the enzymatic oxidation of glucose to gluconic acid. This sensor has tremendous potential for application in glucose biosensing due to the higher sensitivity 2.5 microA/cm2-mM and substantial increment of the anodic peak current from 0.2 microA to 10.5 microA. PMID:22962799

Krishna, Rahul; Titus, Elby; Chandra, Sudeshna; Bardhan, Neel Kanth; Krishna, Rohit; Bahadur, Dhirendra; Gracio, José

2012-08-01

142

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

143

Preparation and characterization of manganese ferrite-based magnetic liposomes for hyperthermia treatment of cancer  

NASA Astrophysics Data System (ADS)

Comparative evaluation of two different methods of magnetic liposomes preparation, namely thin film hydration (TFH) and double emulsion (DE) with different molar ratios of egg-phosphatidyl choline (egg-PC) and cholesterol using lauric acid coated manganese ferrite-based aqueous magnetic fluid, is reported. TFH was found to be a better method of encapsulation and TFH 2:1 (egg-PC: cholesterol) magnetic liposomes showed the highest encapsulation efficiency and comparable heating ability to that of magnetic fluids. Stealth TFH 2:1 magnetic liposomes containing DSPE-PEG 2000 were three-fold more cytocompatible as compared to the magnetic fluid. Stealth TFH 2:1 manganese ferrite-based magnetic liposomes might be useful for hyperthermia treatment of cancer.

Pradhan, Pallab; Giri, Jyotsnendu; Banerjee, Rinti; Bellare, Jayesh; Bahadur, Dhirendra

2007-04-01

144

Magnetic anisotropy and high coercivity of epitaxial Co-ferrite films prepared by pulsed laser deposition  

NASA Astrophysics Data System (ADS)

CoFe2O4 films with different thicknesses (40-200 nm) were prepared on sapphire using pulsed laser deposition at different substrate temperatures. The films on (0001) sapphire showed a (111) epitaxial structure even at a low deposition temperature of 150 °C. The coercivity up to 8.8 kOe could be achieved in the 40 nm film on sapphire deposited at 550 °C. By comparison, the 33 nm film on quartz possesses a nanocrystalline structure with the grain size below 20 nm as well as a strong (111) preferential texture. The highest coercivity (12.5 kOe) up to now was obtained in the 33 nm Co-ferrite films. The study also revealed that high coercivity and large perpendicular anisotropy of these Co-ferrite thin films may be related to the textured structure and large residual strain.

Yin, J. H.; Ding, J.; Liu, B. H.; Yi, J. B.; Miao, X. S.; Chen, J. S.

2007-05-01

145

Solvothermal synthesis of cobalt ferrite nanoparticles loaded on multiwalled carbon nanotubes for magnetic resonance imaging and drug delivery.  

PubMed

Multiwalled carbon nanotube (MWCNT)/cobalt ferrite (CoFe(2)O(4)) magnetic hybrids were synthesized by a solvothermal method. The reaction temperature significantly affected the structure of the resultant MWCNT/CoFe(2)O(4) hybrids, which varied from 6nm CoFe(2)O(4) nanoparticles uniformly coated on the nanotubes at 180°C to agglomerated CoFe(2)O(4) spherical particles threaded by MWCNTs and forming necklace-like nanostructures at 240°C. Based on the superparamagnetic property at room temperature and high hydrophilicity, the MWCNT/CoFe(2)O(4) hybrids prepared at 180°C (MWCNT/CoFe(2)O(4)-180) were further investigated for biomedical applications, which showed a high T(2) relaxivity of 152.8 Fe mM(-1)s(-1) in aqueous solutions, a significant negative contrast enhancement effect on cancer cells and, more importantly, low cytotoxicity and negligible hemolytic activity. The anticancer drug doxorubicin (DOX) can be loaded onto the hybrids and subsequently released in a sustained and pH-responsive way. The DOX-loaded hybrids exhibited notable cytotoxicity to HeLa cancer cells due to the intracellular release of DOX. These results suggest that MWCNT/CoFe(2)O(4)-180 hybrids may be used as both effective magnetic resonance imaging contrast agents and anticancer drug delivery systems for simultaneous cancer diagnosis and chemotherapy. PMID:21664499

Wu, Huixia; Liu, Gang; Wang, Xue; Zhang, Jiamin; Chen, Yu; Shi, Jianlin; Yang, Hong; Hu, He; Yang, Shiping

2011-09-01

146

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

147

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

2014-07-01

148

Structural and magnetic properties of Zn-substituted cobalt ferrites prepared by co-precipitation method.  

PubMed

Zn substituted cobalt ferrite spinels with the general formula Zn(x)Co(1-x)Fe(2)O(4) (with x varying from 0 to 0.5) were synthesized by a co-precipitation method and calcined at 500 °C and 800 °C. It was found that Zn substitution has a big effect in decreasing the Curie temperature (T(c)), from around 440 °C for the undoped sample to ~180 °C with x = 0.5. However, these values were also strongly affected by the pre-calcination temperature of the samples, thus T(C) shifts from ~275 °C for the x = 0.3 sample to ~296 °C after calcination at 500 °C and 800 °C respectively. These effects are due to facilitation of demagnetisation by substitution of the non-magnetic Zn ions and by production of very small nanoparticles. The latter are removed by higher temperature calcinations and so T(C) increases. PMID:21952718

Yaseneva, Polina; Bowker, Michael; Hutchings, Graham

2011-11-01

149

Synthesis and coating of cobalt ferrite nanoparticles: a first step toward the obtainment of new magnetic nanocarriers.  

PubMed

Monodisperse and stable cobalt ferrite (CoFe2O4) nanoparticles (5.4 nm) have been produced, coated with mono- and difunctional phosphonic and hydroxamic acids, and fully characterized (using thermogravimetric analysis (TGA), dynamic light scattering (DLS), IR spectroscopy, transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID) measurements). Cobalt leakage of the coated nanoparticles has been also studied. Magnetic measurements show the possible applications in hyperthermia at low frequencies, and for this reason, water-soluble coated CoFe2O4 can be seen as a first step toward the obtainment of novel systems for biomagnetic applications. PMID:17335257

Baldi, Giovanni; Bonacchi, Daniele; Franchini, Mauro Comes; Gentili, Denis; Lorenzi, Giada; Ricci, Alfredo; Ravagli, Costanza

2007-03-27

150

Preparation and Characterization of Amino-Coated Maghemite Nanoparticles  

Microsoft Academic Search

The ferrous salt and ferric salt were used as raw materials to prepare magnetite (Fe3O4) nanoparticles as precursors, and then maghemite (?-Fe2O3) nanoparticles were obtained from the precursors via high temperature pyrolysis for further oxidation, and corresponding amino-coated maghemite nanoparticles are also obtained via surface modification of 3-aminopropyltriethyloxy silane (APTES). The properties and structure of nanoparticles are characterized by transmission

Lei Zeng; Rong Hu; Zhaohui Wu; Quanguo He

2010-01-01

151

Mössbauer effect studies on mixed lithium–zinc ferrites prepared by solution combustion method  

Microsoft Academic Search

Mössbauer effect studies have been made on lithium ferrites of varying compositions i.e. Li0.5???x\\/2Zn\\u000a x\\u000a Mn0.05Fe2.45???x\\/2O4 prepared by combustion method from stoichiometric aqueous solutions of metal nitrates and oxalyl dihydrazide. In these compositions\\u000a x varies from 0?0.5 in steps of 0.1. The Mössbauer spectral studies reveal that substitution of nonmagnetic Zn2?+? is responsible for successive increase in line-width and change

H. S. Dosanjh; B. S. Randhawa; Nitendar Kumar

2008-01-01

152

Microwave absorption properties of Ba M-type ferrite prepared by a modified coprecipitation method  

Microsoft Academic Search

The electromagnetic wave absorption properties were investigated in the Co–Ti substituted Ba M-type hexagonal ferrites (BaFe9.5(Co1?yTiy)2.5O19 (y=0.4–0.8)), which were prepared by a modified coprecipitation method. This modified chemical coprecipitation method was the combination of coprecipitation and synthesis from a salt melt. The Ba9.5(Co0.4Ti0.6)2.5O19 sample, which was sintered at 1423K for 5h with a Bi2O3 addition of 2wt%, exhibited high permeability

Satoshi Sugimoto; Kazuaki Haga; Toshio Kagotani; Koichiro Inomata

2005-01-01

153

Preparation of conducting silver paste with Ag nanoparticles prepared by e-beam irradiation  

NASA Astrophysics Data System (ADS)

Conducting silver paste was prepared by using Ag nanoparticles which were synthesized by e-beam irradiation method (from KAERI); its conductivity was comparatively determined with Ag nanoparticles which were prepared by thermolysis method (commercial). The silver nanoparticles with the diameter of approximately 150 nm size prepared by e-beam irradiation were mixed with glass frit and sintered for 1 h at 500 °C. It is presumably concluded that the wt% of silver nanoparticle, size distribution and homogenous dispersibility of Ag nanoparticles in the pastes are the critical factors for the high conductivity of the paste. Among the various wt% of silver nanoparticle in the conducting silver pastes, silver paste with 90 wt% of silver nanoparticle has the highest conductivity as 1.6×10 4 S cm -1. This conductivity value is 1.6 times higher than the Ag pastes which were prepared with silver nanoparticles obtained by thermolysis method.

Sohn, Jong Hwa; Pham, Long Quoc; Kang, Hyun Suk; Park, Ji Hyun; Lee, Byung Cheol; Kang, Young Soo

2010-11-01

154

Structural, electrical, magnetic and dielectric properties of rare-earth substituted cobalt ferrites nanoparticles synthesized by the co-precipitation method  

NASA Astrophysics Data System (ADS)

Pure nanoparticles of the rare-earth substituted cobalt ferrites CoRExFe2-xO4 (where RE=Nd, Sm and Gd and x=0.1 and 0.2) were prepared by the chemical co-precipitation method. X-ray diffraction, Transmission electron microscopy (TEM), d.c. electrical conductivity, Magnetic hysteresis and Thermal analysis are utilized in order to study the effect of variation in the rare-earth substitution and its impact on particle size, magnetic properties like MS, HC and Curie temperature. The phase identification of the materials by X-ray diffraction reveals the single-phase nature of the materials. The lattice parameter increased with rare-earth content for x?0.2. The Transmission electron micrographs of Nd-, Sm- and Gd-substituted CoFe2O4 exhibit the particle size 36.1 to 67.8 nm ranges. The data of temperature variation of the direct current electrical conductivity showed definite breaks, which corresponds to ferrimagnetic to paramagnetic transitions. The thermoelectric power for all compound are positive over the whole range of temperature. The dielectric constant decreases with frequency and rare-earth content for the prepared samples. The magnetic properties of rare-earth substituted cobalt ferrites showed a definite hysteresis loop at room temperature. The reduction of coercive force, saturation magnetization, ratio MR/MS and magnetic moments may be due to dilution of the magnetic interaction.

Nikumbh, A. K.; Pawar, R. A.; Nighot, D. V.; Gugale, G. S.; Sangale, M. D.; Khanvilkar, M. B.; Nagawade, A. V.

2014-04-01

155

Preparation and Characterization of Calcium Carbonate Nanoparticles  

NASA Astrophysics Data System (ADS)

Taking calcium supplements can reduce the risk of developing osteoporosis, but they are not readily absorbed in the gastrointestinal tract. Nanotechnology is expected to resolve this problem. In this study, we prepared and characterized calcium carbonate nanoparticle to improve the solubility by using bottom-up method. The experiment was done by titrating calcium chloride with sodium carbonate with the addition of polyvinylpyrrolidone (PVP) as stabilizer, using ultra-turrax. Various concentrations of calcium chloride and sodium carbonate as well as various speed of stirring were used to prepare the calcium carbonate nanoparticles. Evaluations studied were including particle size, polydispersity index (PI) and zeta potential with particle analyzer, surface morphology with scanning electron microscope, and saturated solubility. In addition, to test the ability of PVP to prevent particles growth, short stability study was performed by storing nano CaCO3 suspension at room temperature for 2 weeks. Results show that using 8000 rpm speed of stirring, the particle size tends to be bigger with the range of 500-600 nm (PI between 0.2-0.4) whereas with stirring speed of 4000 rpm, the particle size tends to be smaller with 300-400 nm (PI between 0.2-0.4). Stirring speed of 6000 rpm produced particle size within the range of 400-500 nm (PI between 0.2-0.4). SEM photograph shows that particles are monodisperse confirming that particles were physically stable without any agglomeration within 2 weeks storage. Taken together, nano CaCO3 is successfully prepared by bottom-up method and PVP is a good stabilizer to prevent the particle growth.

Hassim, Aqilah; Rachmawati, Heni

2010-10-01

156

Preparation and characterization of spinel nickel ferrite obtained by the soft mechanochemically assisted synthesis  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? NiFe{sub 2}O{sub 4} has been prepared by a soft mechanochemical route from mixture of powders. ? The spinel phase formation was completed after 25 h. ? The synthesized ferrites have a crystallite size of about 25 and 15 nm. ? Based on Raman research is observed five first-order Raman active modes. ? We were able to estimate the degree of inversion at most 0.82 and 0.66. -- Abstract: Nickel ferrite, NiFe{sub 2}O{sub 4} has been prepared by a soft mechanochemical route from mixture of (1) Ni(OH){sub 2} and ?-Fe{sub 2}O{sub 3} and (2) Ni(OH){sub 2} and Fe(OH){sub 3} powders in a planetary ball mill for varying duration. Soft mechanochemical reaction leading to formation of the NiFe{sub 2}O{sub 4} spinel phase was followed by X-ray diffraction, Raman and infrared spectroscopy, TGA, scanning and transmission microscopy. The spinel phase formation was first observed after 4 h of milling and its formation was completed after 25 h in the both cases. The synthesized NiFe{sub 2}O{sub 4} ferrite has a nanocrystalline structure with a crystallite size of about 20 and 10 nm respectively for the cases (1) and (2). The final grain size in the system (1) is about twice as large as that in the system (2), what is a consequence of different reaction paths in these two processing routes. There are five Raman and four IR active modes. Mössbauer spectroscopy studies implied on the possible cation distribution between the tetrahedral and octahedral sites in formed NiFe{sub 2}O{sub 4} spinel structure. We were able to estimate the degree of inversion at most 0.82 in the case (1) and 0.66 in the case (2).

Lazarevi?, Z.Ž., E-mail: lzorica@yahoo.com [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia); Jovaleki?, ?. [The Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, Belgrade (Serbia)] [The Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, Belgrade (Serbia); Re?nik, A. [Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana (Slovenia)] [Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana (Slovenia); Ivanovski, V.N. [Institute of Nuclear Sciences Vin?a, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia)] [Institute of Nuclear Sciences Vin?a, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Milutinovi?, A.; Rom?evi?, M. [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia)] [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia); Pavlovi?, M.B. [Faculty of Electrical Engineering, University of Belgrade, Bulevar Kralja Aleksandra 73, Belgrade (Serbia)] [Faculty of Electrical Engineering, University of Belgrade, Bulevar Kralja Aleksandra 73, Belgrade (Serbia); Ceki?, B. [Institute of Nuclear Sciences Vin?a, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia)] [Institute of Nuclear Sciences Vin?a, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Rom?evi?, N.Ž. [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia)] [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia)

2013-02-15

157

Synthesis and Thermal Stability of Polycrystalline New Divalent ??- and ?-Ferrites Prepared by Ion Exchange  

NASA Astrophysics Data System (ADS)

Using ion-exchange chemistry the divalent cations Ba 2+, Sr 2+, Ca 2+, Mg 2+ Cd 2+, Pb 2+, Co 2+, Zn 2+, Mn 2+, Fe 2+, and Sn 2+ have been substituted for K + in polycrystalline CdO-stabilized K-??-ferrite samples. Ba, Sr, Ca, Mg, Pb, and Cd ion exchange led to the synthesis of new materials, the divalent M2+ -??-ferrites ( M = Ba, Sr, Ca, Mg) and M2+ -?-ferrites ( M = Cd, Pb), respectively, Co 2+-diffusion resulted in the formation of a spinel-type Co-ferrite. In the case of Zn, Mn, Fe, and Sn the samples decomposed to ?-Fe 2O 3. The thermal stability of the new divalent ??- and ?-ferrites was studied either by high-temperature exchange reactions or by air annealing of the exchanged products. Ba- and Sr-??-ferrites and Pb-?-ferrite converted to M-type hexagonal ferrites with the magnetoplumbite structure. Mg-??-ferrite decomposed to a spinel-type Mg-ferrite, and Ca-??-ferrite and Cd-?-ferrite decomposed to ?-Fe 2O 3. Composition, lattice parameters, SEM photographs, and magnetic properties of the ferrites formed are given. The magnetic susceptibilities of the divalent ??- or ?-ferrites have values between 0.63 and 1.14 × 10 -4 emu/g · Oe at room temperature.

Kalogirou, O.

1993-02-01

158

Permeability and microstructure of manganese modified lithium ferrite prepared by sol–gel auto-combustion method  

Microsoft Academic Search

A series of manganese modified lithium ferrite powders, Li0.5Fe2.5O4 with different content of Mn (0, 0.05, 0.1, 0.15, 0.20, 0.25) were directly prepared by a novel sol–gel auto-combustion method at room temperature. The average particle sizes of as-synthesized powders were 50 nm and exhibited high activity and homogenous chemical composition. The lithium ferrites prepared by as-synthesized powders can be sintered

Xiwei Qi; Ji Zhou; Zhenxing Yue; Zhilun Gui; Longtu Li

2003-01-01

159

Synthesis and assembly of high-quality cobalt ferrite nanocrystals prepared by a modified sol–gel technique  

Microsoft Academic Search

Colloidal cobalt ferrite nanocrystals were produced using a new sol–gel-like synthesis based on the procedure developed by O’Brien et al. (J. Am. Chem. Soc. 123 (2001) 12085) for the synthesis of BaTiO3 nanocrystals. This synthesis involves the single-stage high-temperature hydrolysis of the metal alkoxide precursors to obtain crystalline, uniform, organically coated nanoparticles which are well-dispersed in an organic solvent. The

Tal Meron; Yuri Rosenberg; Yossi Lereah; Gil Markovich

2005-01-01

160

Preliminary evaluation of a 99mTc labeled hybrid nanoparticle bearing a cobalt ferrite core: in vivo biodistribution.  

PubMed

Magnetic nanoparticles have become important tools for imaging a wide range of diseases, improving drug delivery and applying hyperthermic treatment. Iron oxide based nanoparticles have been widely examined, unlike cobalt ferrite based ones. Herein, monodisperse and stable CoFe2O4 nanoparticles have been produced, coated and further stabilized using ethyl 12-(hydroxyamino)-12-oxododecanoate, poly(lactic-co-glycolic acid) and bovine serum albumin. The final product, NBRh1, was fully characterized and has been directly radiolabeled with 99mTc using SnCl1 as the reducing agent in high yields. In vitro stability and hyperthermic properties of 99mTC-NBRh1 were encouraging for further application in low frequencies hyperthermia and biomagnetic applications. In vivo evaluation followed after injection in healthy mice. The planar and SPECT imaging data as well as the biodistribution results were in accordance, showing high liver and spleen uptake as expected starting almost immediately after administration. In conclusion the preliminary results for nanoparticles bearing a cobalt ferrite core justify further investigations towards potential hyperthermic applications, drug transportation and liver or spleen imaging. PMID:22852467

Psimadas, Dimitrios; Baldi, Giovanni; Ravagli, Costanza; Bouziotis, Penelope; Xanthopoulos, Stavros; Franchini, Mauro Comes; Georgoulias, Panagiotis; Loudos, George

2012-08-01

161

Recent advances in nanosized Mn-Zn ferrite magnetic fluid hyperthermia for cancer treatment.  

PubMed

This paper reviews the recent research and development of nanosized manganese zinc (Mn-Zn) ferrite magnetic fluid hyperthermia (MFH) for cancer treatment. Mn-Zn ferrite MFH, which has a targeted positioning function that only the temperature of tumor tissue with magnetic nanoparticles can rise, while normal tissue without magnetic nanoparticles is not subject to thermal damage, is a promising therapy for cancer. We introduce briefly the composition and properties of magnetic fluid, the concept of MFH, and features of Mn-Zn ferrite magnetic nanoparticles for MFH such as thermal bystander effect, universality, high specific absorption rate, the targeting effect of small size, uniformity of hyperthermia temperature, and automatic temperature control and constant temperature effect. Next, preparation methods of Mn-Zn ferrite magnetic fluid are discussed, and biocompatibility and biosecurity of Mn-Zn ferrite magnetic fluid are analyzed. Then the applications of nanosized Mn-Zn ferrite MFH in cancer are highlighted, including nanosized Mn-Zn ferrite MFH alone, nanosized Mn-Zn ferrite MFH combined with As2O3 chemotherapy, and nanosized Mn-Zn ferrite MFH combined with radiotherapy. Finally, the combination application of nanosized Mn-Zn ferrite MFH and gene-therapy is conceived, and the challenges and perspectives for the future of nanosized Mn-Zn ferrite MFH for oncotherapy are discussed. PMID:24730298

Lin, Mei; Huang, Junxing; Sha, Min

2014-01-01

162

Strontium ferrite nanoparticles synthesized in presence of polyvinylalcohol: Phase composition, microstructural and magnetic properties  

NASA Astrophysics Data System (ADS)

Systematic study was devoted to the synthesis of hexagonal strontium ferrite nanoparticles employing polyvinylalcohol as stabilizing agent. Preliminary experiments allowed to select an optimal sol having molar ratio Sr/Fe=12, weight ratio PVA/[Sr+Fe]=1.4 and pH=2.1. The obtained sol were transformed to gels by an evaporation of water at 100 °C and drying at 112 °C under vacuum. The subsequent calcination was carried out for 3 h at 400 °C, achieved by heating rate of 17 K/min. The obtained precursor was used for a detail study of influence of annealing conditions (temperature range 600-700 °C, annealing time 10-190 min) on the resulting properties. Semiquantitative X-ray phase analysis approved a gradual increase of the M-phase content and a gradual growth of M-phase crystallites with temperature and time. Magnetic measurements showed a distinct influence of the phase composition, namely ratio of the contents of M-phase and maghemite on the shape of the magnetic loops, while the crystallite sizes have only a slight effect.

Veverka, P.; Knížek, K.; Pollert, E.; Bohá?ek, J.; Vasseur, S.; Duguet, E.; Portier, J.

2007-02-01

163

Adsorption of cobalt ferrite nanoparticles within layer-by-layer films: a kinetic study carried out using quartz crystal microbalance.  

PubMed

The paper reports on the successful use of the quartz crystal microbalance technique to assess accurate kinetics and equilibrium parameters regarding the investigation of in situ adsorption of nanosized cobalt ferrite particles (CoFe(2)O(4)--10.5 nm-diameter) onto two different surfaces. Firstly, a single layer of nanoparticles was deposited onto the surface provided by the gold-coated quartz resonator functionalized with sodium 3-mercapto propanesulfonate (3-MPS). Secondly, the layer-by-layer (LbL) technique was used to build multilayers in which the CoFe(2)O(4) nanoparticle-based layer alternates with the sodium sulfonated polystyrene (PSS) layer. The adsorption experiments were conducted by modulating the number of adsorbed CoFe(2)O(4)/PSS bilayers (n) and/or by changing the CoFe(2)O(4) nanoparticle concentration while suspended as a stable colloidal dispersion. Adsorption of CoFe(2)O(4) nanoparticles onto the 3-MPS-functionalized surface follows perfectly a first order kinetic process in a wide range (two orders of magnitude) of nanoparticle concentrations. These data were used to assess the equilibrium constant and the adsorption free energy. Alternatively, the Langmuir adsorption constant was obtained while analyzing the isotherm data at the equilibrium. Adsorption of CoFe(2)O(4) nanoparticles while growing multilayers of CoFe(2)O(4)/PSS was conducted using colloidal suspensions with CoFe(2)O(4) concentration in the range of 10(-8) to 10(-6) (moles of cobalt ferrite per litre) and for different numbers of cycles n = 1, 3, 5, and 10. We found the adsorption of CoFe(2)O(4) nanoparticles within the CoFe(2)O(4)/PSS bilayers perfectly following a first order kinetic process, with the characteristic rate constant growing with the increase of CoFe(2)O(4) nanoparticle concentration and decreasing with the rise of the number of LbL cycles (n). Additionally, atomic force microscopy was employed for assessing the LbL film roughness and thickness. We found the film thickness increasing from about 20 to 120 nm while shifting from 3 to 10 CoFe(2)O(4)/PSS bilayers, using the 8.9 × 10(-6) (moles of cobalt ferrite per litre) suspension. PMID:22025281

Alcantara, Gustavo B; Paterno, Leonardo G; Afonso, André S; Faria, Ronaldo C; Pereira-da-Silva, Marcelo A; Morais, Paulo C; Soler, Maria A G

2011-12-28

164

Preparations, characterizations and applications of chitosan-based nanoparticles  

Microsoft Academic Search

Chitosan is a natural polysaccharide prepared by the N-deacetylation of chitin. In this paper we have reviewed the methods\\u000a of preparation of chitosan-based nanoparticles and their pharmaceutical applications. There are five methods of their preparations:\\u000a emulsion cross-linking, emulsion-droplet coalescence, ionic gelation, reverse micellar method and chemically modified chitosan\\u000a method. Chitosan nanoparticles are used as carriers for low molecular weight drug,

Chenguang Liu; Yulong Tan; Chengsheng Liu; Xiguang Chen; Lejun Yu

2007-01-01

165

Preparations, characterizations and applications of chitosan-based nanoparticles  

NASA Astrophysics Data System (ADS)

Chitosan is a natural polysaccharide prepared by the N-deacetylation of chitin. In this paper we have reviewed the methods of preparation of chitosan-based nanoparticles and their pharmaceutical applications. There are five methods of their preparations: emulsion cross-linking, emulsion-droplet coalescence, ionic gelation, reverse micellar method and chemically modified chitosan method. Chitosan nanoparticles are used as carriers for low molecular weight drug, vaccines and DNA. Releasing characteristics, biodistribution and applications are also summarized.

Liu, Chenguang; Tan, Yulong; Liu, Chengsheng; Chen, Xiguang; Yu, Lejun

2007-07-01

166

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

167

Spark plasma sintering of cobalt ferrite nanopowders prepared by coprecipitation and hydrothermal synthesis  

Microsoft Academic Search

Cobalt ferrite exhibits a high coercivity at room temperature and a strong magnetic anisotropy compared to the other spinel ferrites and, consequently appears as an interesting material for permanent magnets and high-density recording. The magnetic properties depend also on the crystallite size. In order to keep the powder properties in a bulk material, dense nanostructured cobalt ferrite has to be

N. Millot; S. Le Gallet; D. Aymes; F. Bernard; Y. Grin

2007-01-01

168

A novel sonication route to prepare anthracene nanoparticles  

SciTech Connect

A novel sonication method has been successfully developed for the preparation of anthracene nanoparticles. The as-prepared nanoparticles are characterized using transmission electron microscopy, ultraviolet-visible absorption spectroscopy, fluorescence excitation and emission spectroscopy. Nanoparticles prepared with sonication are smaller and better dispersed than with magnetic stirring. Surfactants cetyltrimethylammonium bromide, bis(2-ethylhexyl)sodium sulfosuccinate, sodium dodecyl sulfonate and polyvinylpyrrolidone are used to control the size and morphology. Excimer band is found at 445 and 472 nm and possible mechanism is discussed.

Kang Peng; Chen Chunnian; Hao Lingyun; Zhu Chunling; Hu Yuan; Chen Zuyao

2004-04-02

169

Photoswitchable fluorescent nanoparticles: preparation, properties and applications.  

PubMed

This minireview highlights recent advances of research dedicated to photoswitchable fluorescent nanoparticles and their applications. Recently, several strategies have been developed to synthesize nanoparticles with optically switchable emission properties: either fluorescence on/off or dual-alternating-color fluorescence photoswitching. The underlying mechanisms of fluorescence photoswitching enable many different types of photoswitchable fluorescent nanoparticles to change fluorescence colors, thus validating the basis of the initial photoswitching design. Among all possible applications, the usage of photoswitchable fluorescent nanoparticles to empower super-resolution fluorescence imaging and to label biological targets was subsequently reviewed. Finally, we summarize the important areas regarding future research and development on photoswitchable fluorescent nanoparticles. PMID:19746389

Tian, Zhiyuan; Wu, Wuwei; Li, Alexander D Q

2009-10-19

170

Preparation and characterization of YADH-bound magnetic nanoparticles  

Microsoft Academic Search

The covalently binding of yeast alcohol dehydrogenase (YADH) to magnetic nanoparticles via carbodiimide activation was studied. The magnetic nanoparticles Fe3O4 with a mean diameter of 10.6nm were prepared by co-precipitating Fe2+ and Fe3+ ions in an ammonia solution and treating under hydrothermal conditions. Transmission electron microscopy (TEM) micrographs showed that the magnetic nanoparticles remained discrete and had no significant change

Dong-Hwang Chen; Min-Hung Liao

2002-01-01

171

Preparation and characterization of magnetite nanoparticles coated by amino silane  

Microsoft Academic Search

Magnetite nanoparticles were prepared by coprecipitation of Fe2+ and Fe3+ with NH4OH, and then, amino silane was coated onto the surface of the magnetite nanoparticles. Transmission electronic microscopy shows the average size of 7.5 nm in diameter. Powder X-ray diffraction and electronic diffraction measurements show the spinel structure for the magnetite nanoparticles. FT–IR spectra indicate that amino silane molecules have

Ming Ma; Yu Zhang; Wei Yu; Hao-ying Shen; Hai-qian Zhang; Ning Gu

2003-01-01

172

Method for the Preparation of IV-VI Semiconductor Nanoparticles.  

National Technical Information Service (NTIS)

A high temperature (on the order of about 90 degrees C. or above) non-aqueous synthetic procedure for the preparation of substantially monodisperse IV-VI semiconductor nanoparticles (quantum dots) is provided. The procedure includes first introducing a fi...

C. B. Murray D. Talapin K. S. Cho W. Gaschler

2004-01-01

173

Microwave-absorbing characteristics of epoxy resin composites containing nanoparticles of NiZn- and NiCuZn-ferrites  

Microsoft Academic Search

NiZn- and NiCuZn-ferrite nanoparticles (50–70nm) with the chemical formula Ni0.5 Zn0.5Fe2O4 (NiZn) and Ni0.35Cu0.15Zn0.5Fe2O4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83emu\\/g (NiZn) to 91emu\\/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in the frequency range

J. C. Aphesteguy; Abel Damiani; Dalmas DiGiovanni; S. E. Jacobo

2009-01-01

174

Microwave-absorbing characteristics of epoxy resin composites containing nanoparticles of NiZn- and NiCuZn-ferrites  

Microsoft Academic Search

NiZn- and NiCuZn-ferrite nanoparticles (50-70 nm) with the chemical formula Ni0.5 Zn0.5Fe2O4 (NiZn) and Ni0.35Cu0.15Zn0.5Fe2O4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83 emu\\/g (NiZn) to 91 emu\\/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in

J. C. Aphesteguy; Abel Damiani; Dalmas Digiovanni; S. E. Jacobo

2009-01-01

175

Potential of Negatively Charged Pectin Nanoparticles Encapsulating Paclitaxel: Preparation & Characterization  

Microsoft Academic Search

Sugars with their three dimensional structures are important for many biological functions. We report preparation of negatively charged pectin nanoparticles and its efficacy as a drug delivery vehicle for anticancer drug Paclitaxel assessed. Pectin nanoparticles were prepared by ionic gelation having a mean diameter of ~300350nm, and were stable over a wide range of temperature and pH. FT-IR spectra revealed

Anita K. Verma; A. Chanchal; A. Kumar

2011-01-01

176

Preparation and characterization of nanocrystalline disordered lithium ferrite by citrate precursor method  

NASA Astrophysics Data System (ADS)

Nanocrystalline Li 0.5Fe 2.5O 4 have been synthesized by citrate precursor gel formation method. DTA/TG measurements show that the metal citrates decomposed around 489 K followed by formation and crystallization of the ferrite. Nanoparticles with average particle size of 10 and 19 nm were obtained by sintering the samples at 573 and 773 K. XRD patterns show that both the sintered samples are single-phase cubic spinel oxide. XRD and FTIR show that 1:3 ordering is absent in these samples. Cation distribution of these samples show that only small amounts of Li l+ is present on the octahedral sites, and hence cation ordering in the octahedral site is not possible and the sample is disordered. Mössbauer studies show that the spectrum of the 19 nm sample can be fitted to two sextets corresponding to Fe 3+ on A and B sites, and large quadrupole splitting values are due to surface irregularities. The spectrum of the 10 nm sample was fitted to a number of symmetric sextets indicating large particle size distribution.

Dey, S.; Roy, A.; Das, D.; Ghose, J.

2004-03-01

177

Novel Methods of Lipidic Nanoparticle Preparation and Drug Loading  

NASA Astrophysics Data System (ADS)

In improving cancer chemotherapy, lipidic nanoparticle systems for drug delivery, such as liposomes and emulsions, have received much attention because they are capable of delivering their drug payload selectively to cancer cells and of circulating for a long period in the bloodstream. In addition, lipidic nanoparticles have been examined for use in gene delivery as a non-viral vector. Preparation methods of particles and drug loading methods are crucial for the physicochemical properties of nanoparticles, which are the key aspects for pharmaceutical applications. This review describes new preparation methods for nanoparticles and a loading method for drugs using nanotechnology, including an evaluation of nanoparticles from the point of drug release for applications in cancer therapy and gene delivery.

Maitani, Y.

2013-09-01

178

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

179

Zero-valent iron nanoparticles preparation  

SciTech Connect

Graphical abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}] at room temperature and a pressure of 3 atm. The synthesized nanoparticles were spherical and had diameters less than 5 nm. Highlights: ? Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}]. ? The conditions of reaction were at room temperature and a pressure of 3 atm. ? The synthesized nanoparticles were spherical and had diameters less than 5 nm. -- Abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}] at room temperature and a pressure of 3 atm. To monitor the reaction, a stainless steel pressure reactor lined with PTFE and mechanically stirred was designed. This design allowed the extraction of samples at different times, minimizing the perturbation in the system. In this way, the shape and the diameter of the nanoparticles produced during the reaction were also monitored. The results showed the production of zero-valent iron nanoparticles that were approximately 5 nm in diameter arranged in agglomerates. The agglomerates grew to 900 nm when the reaction time increased up to 12 h; however, the diameter of the individual nanoparticles remained almost the same. During the reaction, some byproducts constituted by amino species acted as surfactants; therefore, no other surfactants were necessary.

Oropeza, S. [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico)] [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico); Corea, M., E-mail: mcoreat@yahoo.com.mx [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico); Gómez-Yáñez, C. [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico)] [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico); Cruz-Rivera, J.J. [Universidad Autónoma de San Luis Potosí, Instituto de Metalurgia, Sierra Leona 550, San Luis Potosí, C.P. 78210 (Mexico)] [Universidad Autónoma de San Luis Potosí, Instituto de Metalurgia, Sierra Leona 550, San Luis Potosí, C.P. 78210 (Mexico); Navarro-Clemente, M.E., E-mail: mnavarroc@ipn.mx [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico)

2012-06-15

180

Optical emission spectroscopy as a tool for the biodistribution investigation of cobalt-ferrite nanoparticles in mice  

NASA Astrophysics Data System (ADS)

This study reports on the biodistribution investigation of two magnetic samples both based on cobalt-ferrite nanoparticles, a magnetic fluid sample (CoMF) and a stealth magnetoliposome polyethylene glycol-monolaurate (PEG-ML). Morphology observations and iron and cobalt concentrations were evaluated after treatment of mice upon intravenous injection. Both magnetic samples had an extended distribution throughout all investigated organs. CoMF was quickly eliminated mainly by the fecal via whereas PEG-ML was retained longer in the circulation and slowly eliminated. These differences are probably due to the presence of polyethylene glycol on the PEG-ML surface, recognized to be responsible for the internalization delay of nanoparticles.

Kückelhaus, S.; Tedesco, A. C.; Oliveira, D. M.; Morais, P. C.; Boaventura, G. R.; Lacava, Z. G. M.

2005-05-01

181

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

182

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.

2012-01-01

183

Preparation and Characterization of Mn0.5Zn0.5Fe2O4 @Au Composite Nanoparticles and Its AntiTumor Effect on Hepatocellular Carcinoma Cells  

Microsoft Academic Search

To explore the preparation method and characters of a new gold nanoshells on maganese-zinc ferrite(Mno.5Zno.5Fe2O4@Au) composite nanoparticles. Mno.5Zno.5Fe2O4@Au nanoparticles with core\\/shell structure were synthesized by reduction of Au 3+ with trisodium citrate in the presence of Mno.5Zno.5Fe2O4 magnetic nanoparticles(MZF- NPs) prepared by improved co-preciption with the character of superparamagnetism and detected by transmission electron microscopy(TEM), scanning electron microscopy(SEM), x-ray diffraction(XRD),

Yuntao Li; Jing Liu; Li Wang; Jia Zhang; Ziyu Wang; Zhiqiang Gao; Yuejiao Zhong; Dongsheng Zhang

2011-01-01

184

Hemoglobin loaded polymeric nanoparticles: preparation and characterizations.  

PubMed

In the present work polymeric nanoparticles based on Poly (maleic anhydride-alt-butyl vinyl ether) 5% grafted with m-PEG (2000) and 95% grafted with 2-methoxyethanol (VAM41-PEG) were loaded with human hemoglobin (Hb) and characterized from a physicochemical point of view. The assessment of structural and functional features of the loaded Hb was performed and the effect of the introduction of different reducing agents as aimed at minimizing Hb oxidation during the nanoparticles formulation process, was also investigated. Nanoparticles possessing an average diameter of 138±10 nm and physicochemical features suitable for this kind of application were successfully obtained. Although the oxidation of the protein was not avoided during its loading into nanoparticles, the presence of acidic moieties in the polymeric structure is proposed to be directly involved in the protein inactivation mechanism. PMID:21443949

Dessy, Alberto; Piras, Anna M; Schirò, Giorgio; Levantino, Matteo; Cupane, Antonio; Chiellini, Federica

2011-05-18

185

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....

186

Regio- and chemoselective reduction of nitroarenes and carbonyl compounds over recyclable magnetic ferrite-nickel nanoparticles (Fe(3)O(4)-Ni) by using glycerol as a hydrogen source.  

PubMed

Reduction by magnetic nano-Fe(3)O(4)-Ni: a facile, simple and environmentally friendly hydrogen-transfer reaction that takes place over recyclable ferrite-nickel magnetic nanoparticles (Fe(3)O(4)-Ni) by using glycerol as hydrogen source allows aromatic amines and alcohols to be synthesized from the precursor nitroarenes and carbonyl compounds. PMID:22933355

Gawande, Manoj B; Rathi, Anuj K; Branco, Paula S; Nogueira, Isabel D; Velhinho, Alexandre; Shrikhande, Janhavi J; Indulkar, Utkarsha U; Jayaram, Radha V; Ghumman, C Amjad A; Bundaleski, Nenad; Teodoro, Orlando M N D

2012-10-01

187

Preparation of magnetic fluorescent hollow nanoparticles with multi-layer  

NASA Astrophysics Data System (ADS)

A kind of novel magnetic fluorescent hollow nanoparticles with multi-layer shells by layer-by-layer self-assembly process was presented in this paper. Non-crosslinking poly(acrylic acid) (PAA) nanoparticles as core with 250 nm in diameters were prepared by distillation-precipitation polymerization in acetonitrile with 2, 2'-Azobisisobutyronitrile (AIBN) as initiator and without any stabilizer and crosslinker. Then 4-vinylpyridine (4-VPy) as monomer was selfassembled on the surface of PAA nanoparticles because of hydrogen-bonding effect between the surface carboxyl of PAA nanoparticles and pyridine of 4-VPy. The 4-VPy as first shell layer were crosslinked by ethylene glycol dimethacrylate (EGDMA) by seeds distillation-precipitation polymerization in acetonitrile. The core/shell structure of this kind of nanoparticles was investigated by FT-IR and TEM. We can find that the products had an absorption peak at 1641 cm-1 from the FT-IR, which showed that the vinyl groups had been connected in the polyAA microspheres. After that, the non-crosslinking PAA core was removed under a solution of sodium hydroxide in ethanol-water. On the other hand, CdTe quantum dots (QDs) with about 3 nm in diameters as shell were prepared in aqueous solution with 3- mercaptopropionic acid (MPA) as stabilizer and 1, 6-hexylenediamime modified Fe3O4 nanoparticles with about 11 nm in diameters as core were synthesized in water respectively. Because of the hydrogen-bonding between the surface carboxyl of MPA on CdTe QDs and the amino on Fe3O4 nanoparticles, the core/shell magnetic-fluorescent nanoparticles were obtained. Then, the magnetic-fluorescent nanoparticles as second shell layer were self-assembled on the hollow 4VPy nanoparticles.

Sun, Xiuxue; Zhang, Jimei; Dai, Zhao; Li, Ping; Zhou, Wen; Zheng, Guo

2009-07-01

188

Preparation and characterization of positively charged ruthenium nanoparticles  

Microsoft Academic Search

Positively charged ruthenium nanoparticles were prepared by NaBH4 reduction at room temperature and at pH values lower than 4.9. The ruthenium nanoparticles were characterized by zeta potential measurement, TEM, XPS, and XRD. Particles with a mean diameter of 1.8 nm and a standard deviation of 0.40 nm could be obtained under the experimental conditions. The surface charge on the particles is believed

Jun Yang; Jim Yang Lee; T. C Deivaraj; Heng-Phon Too

2004-01-01

189

Preparation and characterization of propranolol hydrochloride nanoparticles: a comparative study  

Microsoft Academic Search

The water-in-oil-in-water (w\\/o\\/w) emulsification process is the method of choice for the encapsulation inside polymeric particles of hydrophilic drugs such as proteins and peptides which are high molecular weight macromolecules. Our objective was to apply this technique in order to formulate nanoparticles loaded with both a hydrophilic and a low molecular weight drug such as propranolol-HCl. Nanoparticles were prepared using

Nathalie Ubrich; Philippe Bouillot; Christina Pellerin; Maurice Hoffman; Philippe Maincent

2004-01-01

190

New route for preparation and characterization of magnetite nanoparticles  

Microsoft Academic Search

We report here the synthesis of naked magnetic nanoparticles by using a facile method. Magnetic nanoparticles were prepared by mixing and stirring two equivalents of iron(II) chloride tetrahydrate with three equivalents of iron(III) chloride hexahydrate at room temperature. The mixture was treated by adding 100ml of 28% ammonium hydroxide. Immediately, the color of the solution turned from orange to black.

M. A. Abdalla; M. H. Jaafar; Z. A. Al-Othman; S. M. Alfadul; M. Ali Khan

2011-01-01

191

Preparation and characterization of stearic acid-pullulan nanoparticles  

Microsoft Academic Search

For a new anticancer drug carrier, we synthesized 4 compositions of amphiphilic stearic acidconjugated pullulan (SAP) and\\u000a characterized them with FT-IR spectroscopy. Crystalline changes were verified by x-ray diffraction patterns before and after\\u000a synthesis of the SAP conjugate. SAP nanoparticles were prepared by a diafiltration method, and the fluorescence spectroscopy\\u000a using pyrene showed particle self-assembly in water. SAP nanoparticles were

In-Sook Kim; In-Joon Oh

2010-01-01

192

The structure, morphology and magnetic properties of Sr-ferrite powder prepared by the molten-salt method  

NASA Astrophysics Data System (ADS)

Sub-micrometre high-performance Sr-ferrite powder was prepared by a molten-salt method using Na2SO4 as the fluxing agent. In the reaction process, a mixture of superfine powder was pre-sintered at 1150 °C for 3 h and then annealed at 850 °C for 2 h. The as-obtained Sr-ferrite powder is SrFe12O19 with a hexagonal magnetoplumbite structure. We observe that with raising the pre-sintering temperature as well as increasing the annealing temperature and time, there is an enlargement of particle size. We regulated the reaction parameters to optimize the magnetic properties of the Sr-ferrite powder. The structure with the best magnetic properties is quasi-cubic in shape and relatively uniform in size, showing a coercivity of 471.89 kA m?1, a saturation magnetization of 91.51 µWb m kg?1, a remanence ratio of 0.50 and a maximum magnetic energy product of 7.89 kJ m?3. We then studied the effects of particle size, demagnetization factor and magnetocrystalline anisotropy on coercivity. Compared with the conventional ceramic process, the one presented here is more convenient and economical for the production of homogeneous hexagonal ferrite powders of high magnetic performance.

He, Xuemin; Zhong, Wei; Yan, Shiming; Au, Chak-Tong; Lü, Liya; Du, Youwei

2014-06-01

193

Preparation and characterization of nanosize nickel-substituted cobalt ferrites (Co 1? x Ni x Fe 2O 4)  

Microsoft Academic Search

Nanosize nickel-substituted cobalt ferrites were prepared using aerosol route and characterized by TEM, XRD, magnetic and Mössbauer spectroscopy. The particle size of as obtained samples was found to be ?10nm which increases upto ?80nm on annealing at 1200°C. The unit cell parameter ‘a’ decreases linearly with the nickel concentration due to smaller ionic radius of nickel. The saturation magnetization for

Sonal Singhal; J. Singh; S. K Barthwal; K. Chandra

2005-01-01

194

Mössbauer effect studies and X-ray diffraction analysis of cobalt ferrite prepared in powder form by thermal decomposition method  

Microsoft Academic Search

Cobalt ferrite (CoxFe3?xO4) is prepared in powder form by thermal decomposition of iron and cobalt salts and is analysed by X-ray diffraction and Mössbauer\\u000a spectroscopic techniques. The variation of Mössbauer parameters, lattice parameters and crystallite size of the products formed\\u000a with variation in the composition of Fe and Co ratios are studied. The studies confirm the formation of nano-size cobalt

M. D. Joseph Sebastian; B. Rudraswamy; M. C. Radhakrishna; Ramani

2003-01-01

195

Preparation and evaluation of thiomer nanoparticles via high pressure homogenization.  

PubMed

The aim of this study was to establish and evaluate a high pressure homogenization method for the preparation of thiomer nanoparticles. Particles were formulated by incorporation of the model protein horseradish peroxidase in chitosan-glutathione (Ch-GSH) and poly(acrylic acid)-glutathione (PAA-GSH) via co-precipitation followed by air jet milling. The resulting microparticles were suspended in distilled water using an Ultraturax and subsequently micronized by high pressure homogenization. Finally, resulting particles were evaluated regarding size distribution, shape, zeta potential, drug load, protein activity and release behaviour. The mean particle size after 30 cycles with a pressure of 1500 bar was 538 +/- 94 nm for particles consisting of Ch-GSH and 638 +/- 94 nm for particles consisting of PAA-GSH. Nanoparticles of Ch-GSH had a positive zeta-potential of +1.03 mv, whereas nanoparticles from PAA-GSH had a negative zeta potential of -6.21 mv. The maximum protein load for nanoparticles based on Ch-GSH and based on PAA-GSH was 45 +/- 2% and 37 +/- %, respectively. The release profile of nanoparticles followed a first order release kinetic. Thiolated nanoparticles prepared by a high pressure homogenization technique were shown to be stable and provide controlled drug release characteristics. The preparation method described here might be a useful tool for a more upscaled production of nanoparticulate drug delivery systems. PMID:20367028

Hoyer, Herbert; Schlocker, Wolfgang; Greindl, Melanie; Ostermann, Thomas; Bernkop-Schnürch, Andreas

2010-01-01

196

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, Taranjit

2011-12-01

197

Elastic properties of nanocrystalline aluminum substituted nickel ferrites prepared by co-precipitation method  

NASA Astrophysics Data System (ADS)

NiAlxFe2-xO4 (x = 0.0-1.0 in the step of 0.2) spinel ferrite system was prepared by the co-precipitation method. The elemental compositional stoichiometry, microstructure, infrared spectral and elastic properties have been carried out by means of energy dispersive analysis of X-ray (EDAX), scanning electron microscopy (SEM) and infrared spectroscopic (IR) measurements. Infrared spectra were carried out at room temperature in the wavenumber range of 300-800 cm-1. The IR spectra show three major absorption bands. High frequency bands '?1' is assigned to the tetrahedral and low frequency bands '?2' is assigned to the octahedral complex. Small frequency bands '?3' is assigned to Al3+O-2 complexes. Force constant for the tetrahedral and octahedral site was determined by using IR data. Force constant used to calculate the stiffness constants (C11 and C12). Using the values of stiffness constants; elastic moduli such as Young's modulus, bulk modulus, modulus of rigidity, Poisson ratio and Debye temperature were calculated.

Patange, S. M.; Shirsath, Sagar E.; Jadhav, S. P.; Hogade, V. S.; Kamble, S. R.; Jadhav, K. M.

2013-04-01

198

Preparation of Alumina Nanoparticles by Pulsed Wire Discharge in Water  

NASA Astrophysics Data System (ADS)

Alumina nanoparticles were prepared by pulsed wire discharge (PWD) using aluminium wire in deionized water at relative energy of 2, which is the ratio of the charged energy of the capacitor and the vaporization energy of the wire. From voltage and current waveforms during PWD, calculated deposited energy of the wire was larger than the vaporization energy of the wire. Scanning electron microscopy images showed that the prepared Al2O3 nanoparticles were spherical particles with the median particle diameter of 103 nm and the geometric standard deviation of 2.3. The X-ray diffraction analyses indicated that the prepared nanoparticles were identified as ?-Al2O3. From these results, pure ?-Al2O3 with particle size of around 100 nm was successfully synthesized by PWD in water.

Tokoi, Y.; Izuari, Y. M.; Suzuki, T.; Nakayama, T.; Suematsu, H.; Niihara, K.

2011-10-01

199

Synthesis and magnetic properties of CoFe{sub 2}O{sub 4} spinel ferrite nanoparticles doped with lanthanide ions  

SciTech Connect

Lanthanide ions have been doped into cobalt spinel ferrites using an oil-in-water micellar method to form CoLn{sub 0.12}Fe{sub 1.88}O{sub 4} nanoparticles with Ln=Ce, Sm, Eu, Gd, Dy, or Er. Doping with lanthanide ions (Ln{sup III}) modulates the magnetic properties of cobalt spinel ferrite nanoparticles. In particular cases of Gd{sup 3+} or Dy{sup 3+} ions, a dramatic increase in the blocking temperature and coercivity is observed. Indeed, the introduction of only 4% of Gd{sup 3+} ions increases the blocking temperature {similar_to}100 K and the coercivity 60%. Initial studies on the magnetic properties of these doped nanoparticles clearly demonstrate that the relationship between the modulation of magnetic properties and the nature of doped Ln{sup III} ions is interesting but very complex. {copyright} 2001 American Institute of Physics.

Kahn, Myrtil L.; Zhang, Z. John

2001-06-04

200

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

201

The surface chemistry and stability of gold nanoparticles prepared using methanol extract of Eucalyptus camaldulensis  

Microsoft Academic Search

The development of nontoxic, clean techniques for synthesising metal nanoparticles such as gold has attracted increasing attention in recent years. Many reports have been published about the synthesis of gold nanoparticles using plant extracts. However, the stability of these prepared gold nanoparticles has not been investigated. In this research, the stability of gold nanoparticles prepared by Eucalyptus camaldulensis was investigated

Valiolah Elyasi Golmoraj; Mohammad Reza Khoshayand; Mohsen Amini; Kamyar Mollazadeh Moghadamd; Gholamreza Amin; Ahmad Reza Shahverdi

2011-01-01

202

On the Preparation of Single Crystal Ferrite Materials by the Floating Zone Technique.  

National Technical Information Service (NTIS)

The growth of single crystal ferrites, by the floating zone technique, was extensively investigated. A pressure vessel, incorporating a floating zone mechanism was constructed; also, appropriate facilities were provided for high frequency induction heatin...

D. A. Lepore R. C. Puttbach

1964-01-01

203

Magnetic and dielectric interactions in nano zinc ferrite powder: Prepared by self-sustainable propellant chemistry technique  

NASA Astrophysics Data System (ADS)

The structural, magnetic and dielectric properties of nano zinc ferrite prepared by the propellant chemistry technique are studied. The PXRD measurement at room temperature reveal that the compound is in cubic spinel phase, belong to the space group Fd-3m. The unit cell parameters have been estimated from Rietveld refinement. The calculated force constants from FTIR spectrum corresponding to octahedral and tetrahedral sites at 375 and 542 cm-1 are 6.61×102 and 3.77×102 N m-1 respectively; these values are slightly higher compared to the other ferrite systems. Magnetic hysteresis and EPR spectra show superparamagnetic property nearly to room temperature due to comparison values between magnetic anisotropy energy and the thermal energy. The calculated values of saturation magnetization, remenant magnetization, coercive field and magnetic moment supports for the existence of multi domain particles in the sample. The temperature dependent magnetic field shows the spin freezing state at 30 K and the blocking temperature at above room temperature. The frequency dependent dielectric interactions show the variation of dielectric constant, dielectric loss and impedance as similar to other ferrite systems. The AC conductivity in the prepared sample is due to the presence of electrons, holes and polarons. The synthesized material is suitable for nano-electronics and biomedical applications.

Daruka Prasad, B.; Nagabhushana, H.; Thyagarajan, K.; Nagabhushana, B. M.; Jnaneshwara, D. M.; Sharma, S. C.; Shivakumara, C.; Gopal, N. O.; Ke, Shyue-Chu; Chakradhar, R. P. S.

2014-05-01

204

Preparation and characterization of nanoparticles containing an antihypertensive agent.  

PubMed

Isradipine, an antihypertensive agent, was encapsulated by the nanoprecipitation method using polymers including poly(epsilon-caprolactone), poly(D,L-lactide) and poly(d, L-lactide-co-glycolide). In vitro scanning electron microscopy and differential scanning calorimetry were used to characterize the nanoparticles. The average diameters of the nanoparticles ranged from 110 nm to 208 nm. PCL nanoparticles were larger than nanoparticles prepared with the other polymers. The zeta potential of the nanoparticles was negative, with values of about -25 mV which promoted good stabilization of the particles. The amorphous state of PLA and PLAGA non-loaded nanoparticles and the semi-crystalline state of PCL were demonstrated with X-ray diffraction and differential scanning calorimetry. For all nanoparticles, isradipine was found to be totally amorphous in the polymer which suggested that the drug was molecularly dispersed in the matrix. The colloidal suspensions displayed a sustained release profile in comparison with the drug release profile of isradipine in a PEG solution. Results from this investigation suggest that these nanospheres will be a good candidate delivery system for oral administration, to reduce the initial hypotensive peak and to prolong the antihypertensive effect of the drug. PMID:9795032

Leroueil-Le Verger, M; Fluckiger, L; Kim, Y I; Hoffman, M; Maincent, P

1998-09-01

205

Preparation of candesartan and atorvastatin nanoparticles by solvent evaporation.  

PubMed

The solubility, absorption and distribution of a drug are involved in the basic aspects of oral bioavailability Solubility is an essential characteristic and influences the efficiency of the drug. Over the last ten years, the number of poorly soluble drugs has steadily increased. One of the progressive ways for increasing oral bioavaibility is the technique of nanoparticle preparation, which allows many drugs to thus reach the intended site of action. Candesartan cilexetil and atorvastatin, belonging to class II of the biopharmaceutical classification system, were chosen as model active pharmaceutical ingredients in this study. Forty samples were prepared either by antisolvent precipitation/solvent evaporation method or by the emulsion/solvent evaporation technique with various commonly used surface-active excipients as nanoparticle stabilizers. All samples were analyzed by means of dynamic light scattering. The particle size of the determined 36 nanoparticle samples was to 574 nm, whereas 32 samples contained nanoparticles of less than 200 nm. Relationships between solvents and excipients used and their amount are discussed. Based on the results the investigated solvent evaporation methods can be used as an effective and an affordable technique for the preparation of nanoparticles. PMID:23132139

Vaculikova, Eliska; Grunwaldova, Veronika; Kral, Vladimir; Dohnal, Jiri; Jampilek, Josef

2012-01-01

206

Effect of Sintering Temperature on the Structural and Dielectric Properties of Zinc Cadmium Ferrites Prepared by Egg-White Technique  

NASA Astrophysics Data System (ADS)

The effect of cadmium substitution and sintering temperature on the microstructure and dielectric properties of nano ZnCdxFe2-xO4 ferrites (x=0.0, 0.05, 0.1, 0.2, 0.3 and 0.5) has been investigated and prepared by egg-white technique. Electrical conductivity and dielectric measurements have been analysed in the frequency range from 100 Hz to 10 MHz. The variation of the real (??) and imaginary (??) part of dielectric constant, AC conductivity (?AC) and loss tangent (tan ?) with frequency has been studied. It follows the Maxwell-Wagner model based on the interfacial polarization in consonance with the Koop's phenomenological theory. It is found that the permittivity of ZnCdxFe2-xO4 ferrites improved and shows a maximum value (~9 × 103) at 100 Hz for the x=0.1 sample.

Dar, M. Abdullah; Siddiqui, W. A.; Alam, M.

207

Antimicrobial active silver nanoparticles and silver\\/polystyrene core-shell nanoparticles prepared in room-temperature ionic liquid  

Microsoft Academic Search

Uniform silver nanoparticles and silver\\/polystyrene core-shell nanoparticles were successfully synthesized in a room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]·BF4). [BMIM]·BF4 plays a protective role to prevent the nanoparticles from aggregation during the preparation process. Transmission electron micrographs confirm that both silver nanoparticles and core-shell nanoparticles are regular spheres with the sizes in the range of 5–15 nm and 15–25 nm, respectively. The

Jing An; Desong Wang; Qingzhi Luo; Xiaoyan Yuan

2009-01-01

208

Magnetic nanoparticles: preparation, physical properties, and applications in biomedicine  

NASA Astrophysics Data System (ADS)

Finally, we have addressed some relevant findings on the importance of having well-defined synthetic strategies developed for the generation of MNPs, with a focus on particle formation mechanism and recent modifications made on the preparation of monodisperse samples of relatively large quantities not only with similar physical features, but also with similar crystallochemical characteristics. Then, different methodologies for the functionalization of the prepared MNPs together with the characterization techniques are explained. Theorical views on the magnetism of nanoparticles are considered.

Akbarzadeh, Abolfazl; Samiei, Mohamad; Davaran, Soodabeh

2012-02-01

209

Preparation of inorganic silica nanofibers containing silver nanoparticles  

Microsoft Academic Search

Silica nanofibers containing silver nanoparticles were successfully prepared using sol-gel chemistry and electro-spinning\\u000a technique. Solution of tetraethly orthosilicate in ethanol containing silver nitrate was aged to have sufficient viscosity\\u000a and electrospun to form nanofibers. Upon thermal treatment, the gelation reaction between silanols was completed in the prepared\\u000a silica nanofibers, and at the same time, silver ions in the nanofiber changed

Kyung Dan Min; Ji Ho Youk; Young-Je Kwark; Won Ho Park

2007-01-01

210

Magnetic nanoparticles: preparation, physical properties, and applications in biomedicine  

PubMed Central

Finally, we have addressed some relevant findings on the importance of having well-defined synthetic strategies developed for the generation of MNPs, with a focus on particle formation mechanism and recent modifications made on the preparation of monodisperse samples of relatively large quantities not only with similar physical features, but also with similar crystallochemical characteristics. Then, different methodologies for the functionalization of the prepared MNPs together with the characterization techniques are explained. Theorical views on the magnetism of nanoparticles are considered.

2012-01-01

211

A novel approach for the preparation of discrete phosphor nanoparticles  

Microsoft Academic Search

Extensive work has been reported on making nanometre sized phosphors to keep up with continuing trends of high resolution displays and nanotechnology. However most of these nanophosphors suffer from surface agglomeration. Thus, a novel method has been developed to prepare discrete phosphor nanoparticles. The precursor phosphor powders obtained from solution by the urea precipitation method were coated with silica. Coating

Robert Withnall; Supriya Hajare; Shuo Zhang; George R. Fern; Terry G. Ireland; Jack Silver

2010-01-01

212

Mössbauer Studies on Nanosized Rubidium Ferrite (RbFeO2) Prepared by Thermal Decomposition of Rubidium Ferrioxalate Precursor using Precursor Method  

NASA Astrophysics Data System (ADS)

Pure, nanosized rubidium ferrites (RbFeO2) has been prepared from the thermolysis of rubidium trioxalatoferrate (III), Rb3[Fe(C2O4)3].3H2O. Various physico-chemical techniques i.e. Simultaneous TG-DTG, XRD & Mössbauer spectroscopy have been employed for the characterization of intermediates/products formed. Nanosized ferrites are formed at much lower temperature and in less time as compared to that of the conventional ceramic method. Magnetic properties for the ferrite product were also carried out.

Gupta, Manik; Randhawa, B. S.

2011-12-01

213

Visualization of internalization of functionalized cobalt ferrite nanoparticles and their intracellular fate.  

PubMed

In recent years, nanoparticles (NPs) and related applications have become an intensive area of research, especially in the biotechnological and biomedical fields, with magnetic NPs being one of the promising tools for tumor treatment and as MRI-contrast enhancers. Several internalization and cytotoxicity studies have been performed, but there are still many unanswered questions concerning NP interactions with cells and NP stability. In this study, we prepared functionalized magnetic NPs coated with polyacrylic acid, which were stable in physiological conditions and which were also nontoxic short-term. Using fluorescence, scanning, and transmission electron microscopy, we were able to observe and determine the internalization pathways of polyacrylic acid-coated NPs in Chinese hamster ovary cells. With scanning electron microscopy we captured what might be the first step of NPs internalization - an endocytic vesicle in the process of formation enclosing NPs bound to the membrane. With fluorescence microscopy we observed that NP aggregates were rapidly internalized, in a time-dependent manner, via macropinocytosis and clathrin-mediated endocytosis. Inside the cytoplasm, aggregated NPs were found enclosed in acidified vesicles accumulated in the perinuclear region 1 hour after exposure, where they stayed for up to 24 hours. High intracellular loading of NPs in the Chinese hamster ovary cells was obtained after 24 hours, with no observable toxic effects. Thus polyacrylic acid-coated NPs have potential for use in biotechnological and biomedical applications. PMID:23486857

Bregar, Vladimir B; Lojk, Jasna; Suštar, Vid; Verani?, Peter; Pavlin, Mojca

2013-01-01

214

Visualization of internalization of functionalized cobalt ferrite nanoparticles and their intracellular fate  

PubMed Central

In recent years, nanoparticles (NPs) and related applications have become an intensive area of research, especially in the biotechnological and biomedical fields, with magnetic NPs being one of the promising tools for tumor treatment and as MRI-contrast enhancers. Several internalization and cytotoxicity studies have been performed, but there are still many unanswered questions concerning NP interactions with cells and NP stability. In this study, we prepared functionalized magnetic NPs coated with polyacrylic acid, which were stable in physiological conditions and which were also nontoxic short-term. Using fluorescence, scanning, and transmission electron microscopy, we were able to observe and determine the internalization pathways of polyacrylic acid–coated NPs in Chinese hamster ovary cells. With scanning electron microscopy we captured what might be the first step of NPs internalization – an endocytic vesicle in the process of formation enclosing NPs bound to the membrane. With fluorescence microscopy we observed that NP aggregates were rapidly internalized, in a time-dependent manner, via macropinocytosis and clathrin-mediated endocytosis. Inside the cytoplasm, aggregated NPs were found enclosed in acidified vesicles accumulated in the perinuclear region 1 hour after exposure, where they stayed for up to 24 hours. High intracellular loading of NPs in the Chinese hamster ovary cells was obtained after 24 hours, with no observable toxic effects. Thus polyacrylic acid–coated NPs have potential for use in biotechnological and biomedical applications.

Bregar, Vladimir B; Lojk, Jasna; Sustar, Vid; Veranic, Peter; Pavlin, Mojca

2013-01-01

215

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

216

Copper(0) nanoparticles supported on silica-coated cobalt ferrite magnetic particles: cost effective catalyst in the hydrolysis of ammonia-borane with an exceptional reusability performance.  

PubMed

Herein we report the development of a new and cost-effective nanocomposite catalyst for the hydrolysis of ammonia-borane (NH(3)BH(3)), which is considered to be one of the most promising solid hydrogen carriers because of its high gravimetric hydrogen storage capacity (19.6% wt) and low molecular weight. The new catalyst system consisting of copper nanoparticles supported on magnetic SiO(2)/CoFe(2)O(4) particles was reproducibly prepared by wet-impregnation of Cu(II) ions on SiO(2)/CoFe(2)O(4) followed by in situ reduction of the Cu(II) ions on the surface of magnetic support during the hydrolysis of NH(3)BH(3) and characterized by ICP-MS, XRD, XPS, TEM, HR-TEM and N(2) adsorption-desorption technique. Copper nanoparticles supported on silica coated cobalt(II) ferrite SiO(2)/CoFe(2)O(4) (CuNPs@SCF) act as highly active catalyst in the hydrolysis of ammonia-borane, providing an initial turnover frequency of TOF = 2400 h(-1) at room temperature, which is not only higher than all the non-noble metal catalysts but also higher than the majority of the noble metal based homogeneous and heterogeneous catalysts employed in the same reaction. More importantly, they were easily recovered by using a permanent magnet in the reactor wall and reused for up to 10 recycles without losing their inherent catalytic activity significantly, which demonstrates the exceptional reusability of the CuNPs@SCF catalyst. PMID:22856878

Kaya, Murat; Zahmakiran, Mehmet; Ozkar, Saim; Volkan, Mürvet

2012-08-01

217

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

PubMed

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 Cr(3+) and Cr(2)O(7) (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; Sinisterra, Rubén D

2012-01-01

218

Preparation of griseofulvin nanoparticles from water-dilutable microemulsions.  

PubMed

Nanoparticles of griseofulvin, a model drug with poor solubility and low bioavailability, were prepared from water dilutable microemulsions by the solvent diffusion technique. Solvent-in-water microemulsion formulations containing water, butyl lactate, lecithin, taurodeoxycholate sodium salt (TDC) or dipotassium glycyrrhizinate (KG), 1,2-propanediol or ethanol were used. The formation of macroscopically homogeneous, stable, fluid, optically transparent, isotropic solutions (microemulsions) was investigated by constructing pseudo-ternary phase diagrams. In the presence of TDC or KG, microemulsion systems that remained transparent on water dilution could be obtained. The displacement of butyl lactate, with an excess of water, from the internal phase of the microemulsions containing the drug into the external phase, lead to successful fabrication of drug nanosuspensions. Nanoparticle size was dependent on microemulsion composition: using KG, griseofulvin nanoparticles below 100 nm with low polydispersity and an increased dissolution rate were obtained. PMID:12623199

Trotta, Michele; Gallarate, Marina; Carlotti, Maria Eugenia; Morel, Silvia

2003-03-26

219

Development of phosphonate modified Fe (1? x) Mn x Fe 2O 4 mixed ferrite nanoparticles: Novel peroxidase mimetics in enzyme linked immunosorbent assay  

Microsoft Academic Search

A highly facile and feasible strategy on the fabrication of advanced intrinsic peroxidase mimetics based on Mn2+ doped mixed ferrite (MnIIxFeII1?xFeIII2O4) nanoparticles was demonstrated for the quantitative and sensitive detection of mouse IgG (as a model analyte). Mn2+ doped Fe1?xMnxFe2O4 nanoparticles were synthesized using varying ratios of Mn2+:Fe2+ ions and characterized by the well known complementary techniques. The increase of

Dipsikha Bhattacharya; Ananya Baksi; Indranil Banerjee; Rajakumar Ananthakrishnan; Tapas K. Maiti; Panchanan Pramanik

2011-01-01

220

Effect of Cadmium Substitution on Structural and Magnetic Properties of Nano Sized Nickel Ferrite  

NASA Astrophysics Data System (ADS)

The structure and crystal phase of the nanocrystalline powders of Ni1-xCdxFe2O4 (0<=x<=0.5) mixed ferrite, synthesized by wet chemical co-precipitation method, were characterized by X-ray diffraction. Results showed that the lattice parameter increased with increasing Cd concentration. Microstructure was studied by scanning electron microscopy. TG/DTA studies were carried out on co-precipitated sulphate complexes. These studies revealed the low ferritization temperature (650 °C) of the ferrite system synthesized by presently adopted route of synthesis and occurrence of simultaneous decomposition and ferritization processes. Further studies by infrared spectroscopy were also conducted. Moreover, magnetic properties of the prepared nanoparticles were studied by magnetization and a.c. susceptibility measurements. The response of prepared Ni1-xCdxFe2O4 mixed ferrites to magnetic field was investigated. Results show that, magnetic susceptibility, Curie temperature, and effective magnetic moment decreased as the Cd content increases.

Pralhadrao Jadhav, Sanjay; Ghanshamji Toksha, Bhagwan; Marutirao Jadhav, Kamalakar; Dadarao Shinde, Narayan

2010-08-01

221

Mössbauer and magnetic studies of cobalt substituted lithium zinc ferrites prepared by citrate precursor method  

Microsoft Academic Search

Nanocrystalline lithium zinc ferrites substituted with cobalt were synthesized by the citrate precursor method. X-ray diffraction was used to confirm the spinel phase. Mössbauer studies at room temperature were carried out to study the effect of cobalt concentration on the various hyperfine interactions. Variation of the saturation magnetization with respect to composition was discussed. The result shows some anomalous behaviour

Ibetombi Soibam; Sumitra Phanjoubam; Chandra Prakash

2009-01-01

222

Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles  

PubMed Central

Summary Monatomic (Fe, Co) and bimetallic (FePt and CoPt) nanoparticles were prepared by exploiting the self-organization of precursor loaded reverse micelles. Achievements and limitations of the preparation approach are critically discussed. We show that self-assembled metallic nanoparticles can be prepared with diameters d = 2–12 nm and interparticle distances D = 20–140 nm on various substrates. Structural, electronic and magnetic properties of the particle arrays were characterized by several techniques to give a comprehensive view of the high quality of the method. For Co nanoparticles, it is demonstrated that magnetostatic interactions can be neglected for distances which are at least 6 times larger than the particle diameter. Focus is placed on FePt alloy nanoparticles which show a huge magnetic anisotropy in the L10 phase, however, this is still less by a factor of 3–4 when compared to the anisotropy of the bulk counterpart. A similar observation was also found for CoPt nanoparticles (NPs). These results are related to imperfect crystal structures as revealed by HRTEM as well as to compositional distributions of the prepared particles. Interestingly, the results demonstrate that the averaged effective magnetic anisotropy of FePt nanoparticles does not strongly depend on size. Consequently, magnetization stability should scale linearly with the volume of the NPs and give rise to a critical value for stability at ambient temperature. Indeed, for diameters above 6 nm such stability is observed for the current FePt and CoPt NPs. Finally, the long-term conservation of nanoparticles by Au photoseeding is presented.

Han, Luyang; Biskupek, Johannes; Kaiser, Ute; Ziemann, Paul

2010-01-01

223

Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles  

NASA Astrophysics Data System (ADS)

A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al2O3 and Fe3O4, on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An

2014-06-01

224

Preparation of silver nanoparticles using tryptophan and its formation mechanism.  

PubMed

A non-toxic route was used for the preparation of silver nanoparticles using tryptophan (Trp) as reducing/stabilizing agent in the presence of cetyltrimethyl ammonium bromide (CTAB). Role of water soluble neutral polymer poly(vinylpyrrolidone) (PVP) has been studied on the growth of yellow colour silver nanoparticle formation. The synthesized nanostructures were characterized by UV-Visible absorption spectroscopy, transmission electron microscopy (TEM) by observing the size and distribution of silver nanoparticles. As the reaction proceeded, particles grew up to about 10 and 20 nm in the presence and absence of PVP, respectively, as determined by TEM. The formed nanoparticles showed the highest absorption plasmon band at 425 nm. Rate of silver sol formation increases with the [Trp], [CTAB] and [PVP], reaching a limiting value and then decreases with the increase in concentrations of these reagents. It was observed that nanoparticles are spherical, aggregated and poly dispersed in the absence and presence of PVP, respectively. On the basis of kinetic data, a suitable mechanism is proposed and discussed for the silver sol formation. PMID:20801004

Zaheer, Zoya; Malik, Maqsood Ahmad; Al-Nowaiser, F M; Khan, Zaheer

2010-12-01

225

Preparation, structural and morphological studies of Ni doped titania nanoparticles.  

PubMed

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 16nm. 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). PMID:24667428

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

2014-07-15

226

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

227

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

228

Superparamagnetic Particle Size Limit of Mn-Zn Ferrite Nanoparticles Synthesised Through Aqueous Method  

SciTech Connect

Mn0.67Zn0.33Fe2O4 nanoparticles with size ranging from 20 to 80 nm have been synthesized using the modified oxidation method. The Curie temperatures for all the samples are found to be within 630 {+-} 5 K suggesting that there is no size-dependent cation distribution. Moessbauer studies on the synthesized nanoparticles suggest that the critical particle size limit for superparamagnetism to be about 25 nm at 293 K.

Joseyphus, R. Justin [Graduate School of Environmental Studies, Tohoku University, AramakiAza Aoba-ku, Sendai 980-8579 (Japan); Materials Science Centre, Dept. of Nuclear Physics, University of Madras, Guindy Campus, Chennai-25 (India); Narayanasamy, A. [Materials Science Centre, Dept. of Nuclear Physics, University of Madras, Guindy Campus, Chennai-25 (India); Jeyadevan, B.; Shinoda, K.; Tohji, K. [Graduate School of Environmental Studies, Tohoku University, AramakiAza Aoba-ku, Sendai 980-8579 (Japan)

2006-05-15

229

Superparamagnetic Particle Size Limit of Mn-Zn Ferrite Nanoparticles Synthesised Through Aqueous Method  

Microsoft Academic Search

Mn0.67Zn0.33Fe2O4 nanoparticles with size ranging from 20 to 80 nm have been synthesized using the modified oxidation method. The Curie temperatures for all the samples are found to be within 630 +\\/- 5 K suggesting that there is no size-dependent cation distribution. Mössbauer studies on the synthesized nanoparticles suggest that the critical particle size limit for superparamagnetism to be about

R. Justin Joseyphus; A. Narayanasamy; B. Jeyadevan; K. Shinoda; K. Tohji

2006-01-01

230

Preparation and characterization of zeolite framework stabilized cuprous oxide nanoparticles  

Microsoft Academic Search

Zeolite framework stabilized copper(I) oxide nanoparticles (4.8±2.6 nm) were prepared for the first time by using a four step procedure: the ion exchange of Cu2+ ions with the extra framework Na+ ions in Zeolite-Y, the reduction of the Cu2+ ions within the cavities of zeolite with sodium borohydride in aqueous solution, the dehydration of Zeolite-Y with the copper(0) nanoclusters, and the

Mehmet Zahmakiran; Saim Özkar

2009-01-01

231

A novel method for preparing monodispersed polystyrene nanoparticles  

Microsoft Academic Search

A preparation manner for monodispersed polystyrene (PS) nanoparticles polymerized by using a novel addition procedure of a\\u000a monomer is suggested. In systems containing a smaller amount of surfactant compared with conventional microemulsion polymerization,\\u000a the polymerization processes consists of three stages: adding dropwise the first part of the monomer for a few minutes at\\u000a 80C and polymerizing for 1 h; adding

Kaiyi Liu; Zhaoqun Wang

2007-01-01

232

Preparation and characterization of polymer-coated magnetic nanoparticles  

Microsoft Academic Search

Composite materials consisting of polystyrene-coated iron nanoparticles were prepared by the thermal decomposition of iron pentacarbonyl in the presence of polystyrene-tetraethylenepentamine dispersants. The nanocomposites contain both simple core-shell particles of 10-20 nm diameter, and more complex particles (20-100 nm) made from the agglomeration of several core-shell particles. Electron diffraction revealed that the core was composed of iron, in contrast to

N. A. D. Burke; H. D. H. Stover; F. P. Dawson; J. D. Lavers; P. K. Jain; H. Oka

2001-01-01

233

Preparation and characterization of magnetic nanoparticles with controlled magnetization  

Microsoft Academic Search

The effect of molar ratio of two hydrated iron salts used as precursors into a (co)precipitation-based synthesis method, on\\u000a the composition, size and specific saturation magnetization of mixed iron oxides and oxyhydroxides magnetic nanoparticles\\u000a as reaction products, was studied. The preparation procedure is based on a salt-assisted solid-state chemical reaction. The\\u000a obtained products are magnetic multiphase components with the mean

Dumitru-Daniel Herea; Horia Chiriac; Nicoleta Lupu

234

Surface-modified superparamagnetic nanoparticles for drug delivery: preparation, characterization, and cytotoxicity studies  

Microsoft Academic Search

Superparamagnetic iron oxide nanoparticles have been used for many years as magnetic resonance imaging (MRI) contrast agents or in drug delivery applications. In this study, a novel approach to prepare magnetic polymeric nanoparticles with magnetic core and polymeric shell using inverse microemulsion polymerization process is reported. Poly(ethyleneglycol) (PEG)-modified superparamagnetic iron oxide nanoparticles with specific shape and size have been prepared

Ajay Kumar Gupta; Stephen Wells

2004-01-01

235

Preparation of nanoporous titania spherical nanoparticles  

NASA Astrophysics Data System (ADS)

Preparation of nanoporous titania particles from well-defined titania-octadecylamine (titania-ODA) hybrid spherical particles with 450 nm in size, which were prepared by the method reported previously (Chem. Commun., 2009, pp. 6851-6853 [39]; RSC Adv., 2012, vol. 2, pp. 1343-1349 [40]), was studied. ODA was removed by solvent extraction with acidic ethanol to obtain nanoporous titania particles and subsequent calcination led to the formation of nanoporous titania particles with the nanopore size ranging from 2 to 4 nm depending on the calcination temperature. The as-synthesized titania was amorphous and was transformed into anatase (at around 300 °C) and rutile (at around 600 °C) by the heat treatment. The phase transition behavior was discussed in comparison with that of as-synthesized titania-ODA particles without ODA removal. Spherical particles of titania-ODA hybrids with 70 nm in size were also transformed into nanoporous titania particles composed of anatase crystallites by the washing and calcination at 500 °C for 1 h.

Shiba, Kota; Sato, Soh; Matsushita, Takayuki; Ogawa, Makoto

2013-03-01

236

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

237

Non-toxic nanoparticles from phytochemicals: preparation and biomedical application.  

PubMed

Nanoparticles (NPs) have various applications in biomedicine and drug delivery carriers and also are widely used in cosmetics. However, the preparation of biocompatible and non-toxic nanomaterials is a very important issue as most of the starting materials are synthesized using toxic chemical reagents. This review introduces the preparation of biocompatible NPs in a range of their concentrations using phytochemicals for biomedicine and biotechnology. Phytochemicals are natural products that are extracted from plants, vegetables, and fruits. Phytochemicals serve as reducing agents and stabilizers during NP synthesis to convert metal ions to metal NPs in water. Possible applications of such nanomaterials in biomedical sciences are also described in this review. PMID:24263370

Lee, Jaewook; Park, Enoch Y; Lee, Jaebeom

2014-06-01

238

Magnetic nanoparticles: preparation, physical properties, and applications in biomedicine.  

PubMed

Finally, we have addressed some relevant findings on the importance of having well-defined synthetic strategies developed for the generation of MNPs, with a focus on particle formation mechanism and recent modifications made on the preparation of monodisperse samples of relatively large quantities not only with similar physical features, but also with similar crystallochemical characteristics. Then, different methodologies for the functionalization of the prepared MNPs together with the characterization techniques are explained. Theorical views on the magnetism of nanoparticles are considered. PMID:22348683

Akbarzadeh, Abolfazl; Samiei, Mohamad; Davaran, Soodabeh

2012-01-01

239

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 NixCo1-xFe2O4 (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 Co0.4Ni0.6Fe2O4 (154.02 m(2) g(-1)). Co0.4Ni0.6Fe2O4 showed the best catalytic activity for reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 as reducing agent, whereas CoFe2O4 was found to be catalytically inactive. The reduction reaction followed pseudo-first order kinetics. The effect of varying the concentration of catalyst and NaBH4 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 NiFe2O4 nanoparticles as catalyst. PMID:24902783

Singh, Charanjit; Goyal, Ankita; Singhal, Sonal

2014-06-26

240

Fabrication and swimming properties of micro-machine coated with magnetite prepared by ferrite plating  

NASA Astrophysics Data System (ADS)

By the sterolithography technique and the ferrite plating, we have fabricated a magnetic micro-machine which coated Fe3O4. The sterolithography technique enables to form the spiral-shape resinous templates and the ferrite plating enables to coat Fe3O4 uniformly onto these templates from an aqueous solution. The total machine weight is light because a resin of the template body is almost the same density as water. We have verified that the machines swim freely and wirelessly in water by applying a rotational magnetic field. As the machine coated with Fe3O4 has a biocompatibility, there is a possibility of medical micro-robots which swim in human body for medical operations.

Nishimura, K.; Sendoh, M.; Ishiyama, K.; Arai, K. I.; Uchida, Hironaga; Inoue, Mitsuteru

2004-06-01

241

Structural, magnetic and electrical properties of cobalt ferrites prepared by the sol–gel route  

Microsoft Academic Search

Nanosized cobalt ferrites having the general formula CoFe2?xAlxO4 (for x=0.00, 0.25, 0.50) have been synthesized by the sol–gel route. The effect of Al3+ ions on structural, Curie temperature, DC electrical resistivity and dielecltric properties are presented in this paper. From the analysis of powder X-ray diffraction patterns, the nanocrystallite size was calculated by the most intense peak (311) using Scherrer

I. H. Gul; A. Maqsood

2008-01-01

242

Influence of aging time of oleate precursor on the magnetic relaxation of cobalt ferrite nanoparticles synthesized by the thermal decomposition method  

NASA Astrophysics Data System (ADS)

Cobalt ferrite nanoparticles are of interest because of their room temperature coercivity and high magnetic anisotropy constant, which make them attractive in applications such as sensors based on the Brownian relaxation mechanism and probes to determine the mechanical properties of complex fluids at the nanoscale. These nanoparticles can be synthesized with a narrow size distribution by the thermal decomposition of an iron-cobalt oleate precursor in a high boiling point solvent. We studied the influence of aging time of the iron-cobalt oleate precursor on the structure, chemical composition, size, and magnetic relaxation of cobalt ferrite nanoparticles synthesized by the thermal decomposition method. The structure and thermal behavior of the iron-cobalt oleate was studied during the aging process. Infrared spectra indicated a shift in the coordination state of the oleate and iron/cobalt ions from bidentate to bridging coordination. Aging seemed to influence the thermal decomposition of the iron-cobalt oleate as determined from thermogravimmetric analysis and differential scanning calorimetry, where shifts in the temperatures corresponding to decomposition events and a narrowing of the endotherms associated with these events were observed. Aging promoted formation of the spinel crystal structure, as determined from X-ray diffraction, and influenced the nanoparticle magnetic properties, resulting in an increase in blocking temperature and magnetocrystalline anisotropy. Mossbauer spectra also indicated changes in the magnetic properties resulting from aging of the precursor oleate. Although all samples exhibited some degree of Brownian relaxation, as determined from complex susceptibility measurements in a liquid medium, aging of the iron-cobalt oleate precursor resulted in crossing of the in-phase ?'and out-of-phase ?? components of the complex susceptibility at the frequency of the Brownian magnetic relaxation peak, as expected for nanoparticles that relax through a single relaxation mechanism. The resulting nanoparticles would be suitable for sensors based on the Brownian relaxation mechanism and in determining mechanical properties of complex fluids at the size scale of the nanoparticles.

Herrera, Adriana P.; Polo-Corrales, Liliana; Chavez, Ermides; Cabarcas-Bolivar, Jari; Uwakweh, Oswald N. C.; Rinaldi, Carlos

2013-02-01

243

Preparation of nanoparticles and organometallic compounds via the SMAD technique  

NASA Astrophysics Data System (ADS)

The SMAD method is a versatile synthetic technique for preparation of organometallic compounds, colloids and nanostructured materials from metals and semiconductors. In this work we use this technique to prepare beta-diketonate complexes of Ba and Cu, nanoparticles of Fe-SiO and copper, and for first time nanoparticles of ionic salt-like compounds. The evaporation and cocondensation of Fe, SiO, and an organic solvent, produces nanoparticles of Fe-SiO that when heat treated and passivated, acquire a core-shell structure that protects the iron core from oxidation, preserving its magnetic properties. beta-Diketonate complexes of Ba and Cu have been prepared free of water and with a considerable purity. Moreover, a striking finding was the dependence of the reactivity of the copper particles with their size toward the formation of the beta-diketonate complex. Nanocrystalline particles of copper have been prepared, and their chemical and catalytic reactivity have been tested in the Ullman reaction and the hydrogenation of CO2 to form CH3OH. Their chemical reactivity in the Ullman reaction is proportional to their surface area, and more reactive that those found in literature, with a maximum yield of 90% biphenyl at 150°C after 6 h. for the Cu*/toluene sample. Their catalytic activity tested using nanocrystalline ZnO as a support, resulted in a maximum conversion of 80% from CO2 to CH3OH. Nanocrystalline LiF particles have been successfully prepared with surface areas of 230--520 m2/g and with crystallite size of 5--10 nm. These particles present resistance to sintering when heated from room temperature up to 200°C. These samples can be densified without crystallite growth.

Ponce, Audaldo A.

244

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

245

Preparation and applications of ZnSe nanoparticles  

NASA Astrophysics Data System (ADS)

Semiconductor nanoparticles have been attracting widespread scientific and technological interest due to their unique size-tunable optical and electronic properties. The ZnSe nanoparticles have wide-ranging applications in laser, optical instruments, etc. because it has a wide band gap and transmittance range, high luminescence efficiency, low absorption coefficient, and excellent transparency to infrared. ZnSe nanoparticles have been prepared at room temperature. Zinc chloride 99 mM of 4 mL is added to 2.2g PVA. Volume of the solution is made up to 50 mL by bidistilled water. The Solution is left for 24 h at room temperature to swell. After that the solution is warmed up to 60°C and stirred for 4 h until viscous transparent solution was obtained. One milliliter of Sodium Hydrogen Selenide was dropped into the solution with gentle stirring. Solution is casted on flat glass plate dishes. After the solvent evaporation, a thin film containing ZnSe nanoparticles are obtained. The film is washed with de-ionized water to remove other soluble salts before measurements.

Ravindranadh, K.; Shekhawat, M. S.; Rao, M. C.

2013-06-01

246

Preparation of poly(lactic acid)\\/chitosan nanoparticles for anti-HIV drug delivery applications  

Microsoft Academic Search

Poly(lactic acid) (PLA)\\/chitosan (CS) nanoparticles were prepared by emulsion method for anti-HIV drug delivery applications. The prepared PLA\\/CS nanoparticles were characterized using DLS, SEM, and FTIR. The hydrophilic antiretroviral drug Lamivudine was loaded into PLA\\/CS nanoparticles. The encapsulation efficiency and in-vitro drug release behaviour of drug loaded PLA\\/CS nanoparticles were studied using UV spectrophotometer. In addition, the cytotoxicity of the

Ashish Dev; N. S. Binulal; A. Anitha; S. V. Nair; T. Furuike; H. Tamura; R. Jayakumar

2010-01-01

247

Preparation of barium titanate nanoparticle sphere arrays and their dielectric properties  

Microsoft Academic Search

Barium titanate (BaTiO3) nanoparticles from 27 to 192 nm were prepared by the 2-step thermal decomposition method from barium titanyl oxalate nanoparticles. These particles were dispersed well into 1-propanol, and dense BaTiO3 nanoparticle sphere arrays without stress-field were prepared by the meniscus method. Temperature dependence of dielectric properties was successfully measured using these dense nanoparticle sphere arrays, and size effect

Satoshi Wada; Aki Yazawa; Takuya Hoshina; Yoshikazu Kameshima; Hirofumi Kakemoto; Takaaki Tsurumi; Yoshihiro Kuroiwa

2008-01-01

248

Preparation of avidin-labelled gelatin nanoparticles as carriers for biotinylated peptide nucleic acid (PNA).  

PubMed

The possibility of preparing uniform nanoparticles consisting of proteins such as gelatin followed by covalent linkage of avidin was investigated. Gelatin nanoparticles were prepared by two step desolvation. Functional groups at the surface of the particulate system were quantified with site-specific reagents. The surface of the nanoparticles was thiolated and avidin was covalently attached to the nanoparticles via a bifunctional spacer at high levels. Biotinylated peptide nucleic acid (PNA) was effectively complexed by the avidin-conjugated nanoparticles. Avidin-conjugated protein nanoparticles should prove as potential carrier system for biotinylated drug derivatives in antisense therapy. PMID:10699706

Coester, C; Kreuter, J; von Briesen, H; Langer, K

2000-03-10

249

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

250

Electron spin resonance studies on quantum tunneling in spinel ferrite nanoparticles  

Microsoft Academic Search

The electron spin resonance (ESR) spectrometer, a very sensitive instrument with fast detecting window to explore quantum phase transitions for magnetic nanoparticles, was exploited to study the fascinating interplay between thermal and quantum fluctuations in the vicinity of a quantum critical point. We have measured ESR in ferrofluid samples containing nanosize particles of Fe2O3. The evolution of the ESR spectrum

C. T. Hsieh; J. T. Lue

2003-01-01

251

Electron spin resonance studies on quantum tunneling in spinel ferrite nanoparticles  

Microsoft Academic Search

The electron spin resonance (ESR) spectrometer, a very sensitive instrument with fast detecting window to explore quantum phase transitions for magnetic nanoparticles, was exploited to study the fascinating interplay between thermal and quantum fluctuations in the vicinity of a quantum critical point. We have measured ESR in ferrofluid samples containing nanosize particles of Fe 2O 3. The evolution of the

Chang-Tsun Hsieh; Juh-Tzeng Lue

2003-01-01

252

Luminol-silver nitrate chemiluminescence enhancement induced by cobalt ferrite nanoparticles.  

PubMed

CoFe(2)O(4) nanoparticles (NPs) could stimulate the weak chemiluminescence (CL) system of luminol and AgNO(3), resulting in a strong CL emission. The UV-visible spectra, X-ray photoelectron spectra and TEM images of the investigated system revealed that AgNO(3) was reduced by luminol to Ag in the presence of CoFe(2)O(4) NPs and the formed Ag covered the surface of CoFe(2)O(4) NPs, resulting in CoFe(2)O(4)-Ag core-shell nanoparticles. Investigation of the CL reaction kinetics demonstrated that the reaction among luminol, AgNO(3) and CoFe(2)O(4) NPs was fast at the beginning and slowed down later. The CL spectra of the luminol - AgNO(3) - CoFe(2)O(4) NPs system indicated that the luminophor was still an electronically excited 3-aminophthalate anion. A CL mechanism has been postulated. When the CoFe(2)O(4) NPs were injected into the mixture of luminol and AgNO(3), they catalyzed the reduction of AgNO(3) by luminol to produce luminol radicals and Ag, which immediately covered the CoFe(2)O(4) NPs to form CoFe(2)O(4)-Ag core-shell nanoparticles, and the luminol radicals reacted with the dissolved oxygen, leading to a strong CL emission. With the continuous deposition of Ag on the surface of CoFe(2)O(4) NPs, the catalytic activity of the core-shell nanoparticles was inhibited and a decrease in CL intensity was observed and also a slow growth of shell on the nanoparticles. PMID:21400653

Shi, Wenbing; Wang, Hui; Huang, Yuming

2011-01-01

253

Microwave ferrite materials and devices  

Microsoft Academic Search

The crystal structure of ferrites including garnets and their methods of preparation are first reviewed. This is followed by an examination of microwave ferrite devices and their application to actual systems. Sufficient theoretical details as well as an extensive though not exhaustive list of references are included for ready reference. The most widely used microwave ferrite device is the isolator,

R. Soohoo

1968-01-01

254

Effect of annealing in a reductive environment on the magnetic properties of barium ferrite nanoparticles doped with Ti4+ and Co2+  

NASA Astrophysics Data System (ADS)

It was found experimentally that the annealing of BaFe10.6Co0.7Ti0.7O19 and BaFe10.2Co0.9Ti0.9O19 complex magnetic oxide nanoparticles in paraffin vapor irreversibly increases their coercive force H c and saturation magnetization M s to the H c and M s values for barium ferrite BaFe12O19. The annealing of these nanoparticles, and of particles of magnetic oxides CrO2, ?-Fe2O3, and BaFe12O19 in air and in paraffin vapor, has not been shown to affect their H c and M s values. An explanation in terms of diffusion self-purification of nanoparticles from ion impurities activated by chemical processes on their surface is offered.

Petinov, V. I.

2011-10-01

255

Characterization of binary gold/platinum nanoparticles prepared by sonochemistry technique  

NASA Astrophysics Data System (ADS)

Aqueous solutions with Au 3+and Pt 4+ ions and additives of surfactants (SDS or PEG-MS) were irradiated with an ultrasound at 200 kHz with an input power of 4.2 W/cm 2, and colloidal nanoparticles were prepared. The prepared nanoparticles were characterized by XRD, TEM, HRTEM, EDX and 197Au Mössbauer spectroscopy. It was found that the structures of nanoparticles were changed with the surfactants; Au and Pt nanoparticles were prepared individually by using SDS, and bimetallic Au/Pt alloy nanoparticles with a core-shell structure were produced in the presence of PEG-MS.

Nakanishi, M.; Takatani, H.; Kobayashi, Y.; Hori, F.; Taniguchi, R.; Iwase, A.; Oshima, R.

2005-02-01

256

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

257

Preparation, and magnetic and electromagnetic properties of La-doped strontium ferrite films  

Microsoft Academic Search

SrLaxFe12?xO19 films (x=0–1.0) with large magneto-crystalline anisotropy were synthesized on SiO2 substrate by sol–gel and self-propagating high-temperature synthesis technique. The films were characterized by various experimental techniques including X-ray diffraction analysis, Field Emission Scanning Electron Microscope, Atomic Force Microscopy, Vibrating Sample Magnetometry and vector network analyzer. The results show that La ions completely enter into strontium ferrite lattice without changing

Y. Q. Li; Y. Huang; S. H. Qi; F. F. Niu; L. Niu

2011-01-01

258

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

259

Effect of light on the magnetic properties of cobalt ferrite nanoparticles  

Microsoft Academic Search

We report variations in the coercivity of CoFe2O4 nanoparticles as a function of particle size, temperature and light intensity. For 30 nm particles, this change in was 2300 Oe at 10 K, 120 Oe at 170 K, for a light intensity of under 2 milliwatts. The remanent magnetization was nearly unchanged by illumination. A simple model of optical absorption followed

Anit K. Giri; Kelly Pellerin; Wanida Pongsaksawad; Monica Sorescu; Sara A. Majetich

2000-01-01

260

Magnetic memory effects in nickel ferrite/polymer nanocomposites  

NASA Astrophysics Data System (ADS)

Memory effects are reported in the field cooled (FC) magnetization of pure nickel ferrite powders and nickel ferrite nanocomposites prepared by the solution casting method. Studies carried out at different concentrations of the nanocomposite indicate that memory effects are suppressed with increasing concentration of the magnetic component in the nanocomposite. This is linked to the increase in the dipolar interaction strength in the nanocomposites, which increase with increasing concentration, as confirmed by the Henkel plots. Model simulations of the FC magnetization carried out on an interacting array of monodispersed magnetic nanoparticles indicate that growing cluster sizes inhibit memory effects.

Malik, Rakesh; Sehdev, Neeru; Lamba, Subhalakshmi; Sharma, Parmanand; Makino, Akihiro; Annapoorni, Subramanian

2014-03-01

261

Synthesis and thermal stability of polycrystalline new divalent [beta][double prime]- and [beta]-ferrites prepared by ion exchange  

SciTech Connect

Using ion-exchange chemistry the divalent cations Ba[sup 2+], Sr[sup 2+], Ca[sup 2+], Mg[sup 2+], Cd[sup 2+], Pb[sup 2+], Co[sup 2+], Zn[sup 2+], Mn[sup 2+], Fe[sup 2+], and Sn[sup 2+] have been substituted for K[sup +] in polycrystalline CdO-stabilized K-[beta][double prime]-ferrite samples. Ba, Sr, Ca, Mg, Pb, and Cd ion exchange led to the synthesis of new materials, the divalent M[sup 2+]-[beta][double prime]-ferrites (M = Ba, Sr, Ca, Mg) and M[sup 2+]-[beta]-ferrites (M = Cd, Pb), respectively. Co[sup 2+]-diffusion resulted in the formation of a spinel-type Co-ferrite. In the case of Zn, Mn, Fe, and Sn the samples decomposed to [alpha]-Fe[sub 2]O[sub 3]. The thermal stability of the new divalent [beta][double prime]- and [beta]-ferrites was studied either by high-temperature exchange reactions or by air annealing of the exchanged products. Ba- and Sr-[beta][double prime]-ferrites and Pb-[beta]-ferrite converted to M-type hexagonal ferrites with the magnetoplumbite structure, Mg-[beta][double prime]-ferrite decomposed to a spinel-type Mg-ferrite, and Ca-[beta][double prime]-ferrite and Cd-[beta]-ferrite decomposed to [alpha]-Fe[sub 2]O[sub 3]. Composition, lattice parameters, SEM photographs, and magnetic properties of the ferrites formed are given. The magnetic susceptibilities of the divalent [beta][double prime]- or [beta]-ferrites have values between 0.63 and 1.14 [times] 10[sup [minus]4] emu/g[center dot]Oe at room temperature. 41 refs., 1 fig., 4 tabs.

Kalogirou, O. (Univ. of Hamburg (Germany) Aristotle Univ., Thessaloniki (Greece))

1993-02-01

262

Effect of retrogradation time on preparation and characterization of proso millet starch nanoparticles.  

PubMed

Starch nanoparticles were prepared from proso millet starch using a green and facile method combined with enzymolysis and recrystallization. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA) were used to characterize the morphology and crystal structure of the starch nanoparticles prepared with different retrogradation time (0.5, 4, 12, and 24h). The results showed that the sizes of the starch nanoparticles were between 20nm and 100nm. The crystal pattern changed from A-type (native starch) to B-type (nanoparticles), and the relative crystallinity of the nanoparticles increased obviously, as compared with the native starch. The nanoparticles prepared with the 12h retrogradation time had the highest degree of crystallinity (47.04%). Compared to conventional acid hydrolysis to make starch nanoparticles, the present approach has the advantage of being quite rapid and presenting a higher yield (about 55%). PMID:25037338

Sun, Qingjie; Gong, Min; Li, Ying; Xiong, Liu

2014-10-13

263

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

264

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

265

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

266

CO Responses of Sensors Based on Cerium Oxide Thick Films Prepared from Clustered Spherical Nanoparticles  

PubMed Central

Various types of CO sensors based on cerium oxide (ceria) have been reported recently. It has also been reported that the response speed of CO sensors fabricated from porous ceria thick films comprising nanoparticles is extremely high. However, the response value of such sensors is not suitably high. In this study, we investigated methods of improving the response values of CO sensors based on ceria and prepared gas sensors from core-shell ceria polymer hybrid nanoparticles. These hybrid nanoparticles have been reported to have a unique structure: The core consists of a cluster of ceria crystallites several nanometers in size. We compared the characteristics of the sensors based on thick films prepared from core-shell nanoparticles with those of sensors based on thick films prepared from conventionally used precipitated nanoparticles. The sensors prepared from the core-shell nanoparticles exhibited a resistance that was ten times greater than that of the sensors prepared from the precipitated nanoparticles. The response values of the gas sensors based on the core-shell nanoparticles also was higher than that of the sensors based on the precipitated nanoparticles. Finally, improvements in sensor response were also noticed after the addition of Au nanoparticles to the thick films used to fabricate the two types of sensors.

Izu, Noriya; Matsubara, Ichiro; Itoh, Toshio; Akamatsu, Takafumi; Shin, Woosuck

2013-01-01

267

Preparation of gold nanoparticles\\/graphene hybrid using 4-mercaptobenzoyl functionalized graphene nanosheets as templates  

Microsoft Academic Search

We report an effective and simple route to prepare gold nanoparticles\\/graphene hybrid via the way of chemical functionalization. First, graphene nanosheets were functionalized with 4-mercaptobenzonic acid via a direct Friedel-Crafts acylation reaction in a polyphosphoric acid\\/phosphorus pentoxide medium. Second, gold nanoparticles were prepared from the in situ reduction of gold (III) chloride trihydrate by sodium borohydride. Subsequently, gold nanoparticles were

Tuan Anh Pham; Jong Su Kim; Don Kim; Yeon Tae Jeong

2012-01-01

268

Preparation and characteristics of DNA-nanoparticles targeting to hepatocarcinoma cells  

Microsoft Academic Search

AIM: To prepare thymidine kinase gene (TK gene) nanoparticles and to investigate the expression of TK gene. METHODS: Poly(D,L-lactic-co-glycolic acid) (PLGA), a biodegradable and biocompatible polymer, was used to prepare recombinant plasmid PEGFP-AFP nanoparticles by a double-emulsion evaporation technique. Characteristics of the nanoparticles were investigated in this study, including morphology, entrapment efficiency, and tissue distribution. The expression of TK gene

Qin He; Ji Liu; Xun Sun; Zhi-Rong Zhang

2004-01-01

269

Duloxetine HCl lipid nanoparticles: preparation, characterization, and dosage form design.  

PubMed

Solid lipid nanoparticles (SLNs) of duloxetine hydrochloride (DLX) were prepared to circumvent the problems of DLX, which include acid labile nature, high first-pass metabolism, and high-dosing frequency. The DLX-SLNs were prepared by using two different techniques, viz. solvent diffusion method and ultrasound dispersion method, and evaluated for particle size, zeta potential, entrapment efficiency, physical characteristics, and chemical stability. Best results were obtained when SLNs were prepared by ultrasound dispersion method using glyceryl mono stearate as solid lipid and DLX in ratio of 1:20 and mixture of polysorbate 80 and poloxamer 188 as surfactant in concentration of 3%. The mean particle size of formulation and entrapment efficiency was 91.7 nm and 87%, respectively, and had excellent stability in acidic medium. Differential scanning calorimetry and X-ray diffraction data showed complete amorphization of DLX in lipid. In vitro drug release from SLNs was observed for 48 h and was in accordance with Higuchi kinetics. In vivo antidepressant activity was evaluated in mice by forced swim test. DLX-SLNs showed significant enhancement in antidepressant activity at 24 h when administered orally in comparison to drug solution. These results confirm the potential of SLNs in enhancing chemical stability and improving the efficacy of DLX via oral route. The SLN dispersion was converted into solid granules by adsorbing on colloidal silicon dioxide and characterized for particle size after redispersion, morphology, and flow properties. Results indicated that nanoparticles were successfully adsorbed on the carrier and released SLNs when dispersed in water. PMID:22167415

Patel, Ketan; Padhye, Sameer; Nagarsenker, Mangal

2012-03-01

270

Microstructure and mechanical properties of oxide dispersion strengthened ferritic steel prepared by a novel route  

NASA Astrophysics Data System (ADS)

Nanocrystalline oxide dispersion strengthened (ODS) ferritic steel powders with nominal composition of Fe-14Cr-3W-0.2Ti-0.3Y was synthesized using a sol-gel method combining with hydrogen reduction. X-ray diffraction patterns show that pure Fe-14Cr-3W-0.2Ti-0.3Y body-centered-cubic phase was obtained at a reduction temperature of 1200 °C for 3 h. Using such powders the ODS steel was produced by spark plasma sintering (SPS) technique. The energy dispersive spectrometry mapping and transmission electron microscopy results indicate that the oxide particles of Y2Ti2O7 with an average size of 55 nm and particle number density of 3.2 × 1019 m-3 are homogeneously dispersed in the steel matrix. The tensile strength and uniform elongation of the steel that was SPS sintered and mechanically-thermally treated at 1100 °C under a uniaxial pressure reach 1070 MPa and 15%, respectively.

Sun, Q. X.; Zhang, T.; Wang, X. P.; Fang, Q. F.; Hao, T.; Liu, C. S.

2012-05-01

271

Development of oxide dispersion strengthened ferritic steel prepared by chemical reduction and mechanical milling  

NASA Astrophysics Data System (ADS)

The oxide dispersion strengthened ferritic steel with a nominal composition of Fe-14Cr-2W-0.5Ti-0.06Si-0.2V-0.1Mn-0.05Ta-0.03C-0.3Y2O3 (14Cr-ODS) was fabricated by sol-gel method in combination with hydrogen reduction, mechanical alloying (MA) and hot isostatic pressing (HIP) techniques. Pure Fe-1.5Y2O3 precursor was obtained by a sol-gel process and a reduction process at 650 °C for 3 h and pure 14Cr-ODS alloy powders were obtained from this precursor and the alloying metallic powders by mechanical alloying. The microstructure analysis investigated by transmission electron microscopy (TEM) and energy dispersive spectrometry (EDS) reveal that Y-Ti-O complexes and V-Ti-O complexes with a main particle size of 8 nm are formed in the 14Cr-ODS steel matrix. After HIP sintering the weight and the relative density of the compacted ingots are about 0.8 kg and 99.7%. The uniform elongation and ultimate tensile strength of the ODS steel obtained by HIP after annealing at 1100 °C for 5 h are about 13% and 840 MPa, respectively.

Sun, Q. X.; Fang, Q. F.; Zhou, Y.; Xia, Y. P.; Zhang, T.; Wang, X. P.; Liu, C. S.

2013-08-01

272

Preparation and characterization of solid lipid nanoparticles loaded with doxorubicin.  

PubMed

Solid lipid nanoparticles (SLN) loaded with doxorubicin were prepared by solvent emulsification-diffusion method. Glyceryl caprate (Capmul)MCM C10) was used as lipid core, and curdlan as the shell material. Dimethyl sulfoxide (DMSO) was used to dissolve both lipid and drug. Polyethylene glycol 660 hydroxystearate (Solutol)HS15) was employed as surfactant. Major formulation parameters were optimized to obtain high quality nanoparticles. The mean particle size measured by photon correlation spectroscopy (PCS) was 199nm. The entrapment efficiency (EE) and drug loading capacity (DL), determined with fluorescence spectroscopy, were 67.5+/-2.4% and 2.8+/-0.1%, respectively. The drug release behavior was studied by in vitro method. Cell viability assay showed that properties of SLN remain unchanged during the process of freeze-drying. Stability study revealed that lyophilized SLN were equally effective (p<0.05) after 1 year of storage at 4 degrees C. In conclusion, SLN with small particle size, high EE, and relatively high DL for doxorubicin can be obtained by this method. PMID:19406231

Subedi, Robhash Kusam; Kang, Keon Wook; Choi, Hoo-Kyun

2009-06-28

273

Polyelectrolyte/magnetite nanoparticle multilayers: preparation and structure characterization.  

PubMed

Polyelectrolyte composite planar films containing a different number of iron oxide (Fe3O4) nanoparticle layers have been prepared using the layer-by-layer adsorption technique. The nanocomposite assemblies were characterized by ellipsometry, UV-vis spectroscopy, and AFM. Linear growth of the multilayer thickness with the increase of the layer number, N, up to 12 reflects an extensive character of this parameter in this range. A more complicated behavior of the refractive index is caused by changes in the multilayer structure, especially for the thicker nanocomposites. A quantitative analysis of the nanocomposite structure is provided comparing a classical and a modified effective medium approach taking into account the influence of light absorption by the Fe3O4 nanoparticles on the complex refractive index of the nanocomposite and contributions of all components to film thickness. Dominant influence of co-adsorbed water on their properties was found to be another interesting peculiarity of the nanocomposite film. This effect, as well as possible film property modulation by light, is discussed. PMID:17958452

Grigoriev, D; Gorin, D; Sukhorukov, G B; Yashchenok, A; Maltseva, E; Möhwald, H

2007-11-20

274

Preparation, characterization and cytotoxicity of schizophyllan/silver nanoparticle composite.  

PubMed

Silver nanoparticles (Ag-NPs) have been successfully prepared with a simple and "green" chemical reduction method. Triple helical schizophyllan (SPG) was used for the first time as reducing and stabilizing agents. The effect of temperature, silver nitrate/schizophyllan concentrations, pH of the reactions medium and the reaction time were investigated. The obtained schizophyllan/Ag-NP was characterized by UV-vis spectroscopy, TEM, DLS, X-ray diffraction, TGA, and ATR-FTIR. The results revealed that, Ag-NPs attached to SPG through a strong non-covalent interaction, leading to good dispersion of Ag-NPs with a diameter of 6 nm within the biopolymer matrix. By increasing the pH of the reaction medium, the triple helical structure of SPG was partially broken. The SPG/AgNP nanocomposite was non-toxic for mouse fibroblast line (NIH-3T3) and human keratinocyte cell line (HaCaT). PMID:24507278

Abdel-Mohsen, A M; Abdel-Rahman, Rasha M; Fouda, Moustafa M G; Vojtova, L; Uhrova, L; Hassan, A F; Al-Deyab, Salem S; El-Shamy, Ibrahim E; Jancar, J

2014-02-15

275

Preparation and characterization of Fe2O3 nanoparticles  

NASA Astrophysics Data System (ADS)

Nano particles hematite (Fe2O3) with good crystallinity were prepared by Pechini method. Hematite (Fe2O3) has emerged as a promising photo-electrode material due to its significant light absorption, chemical stability in aqueous environments, and ample abundance. Photoelectrochemical cells offer the ability to convert electromagnetic energy from our largest renewable source, the Sun, to stored chemical energy through the splitting of water into molecular oxygen and hydrogen. The structure and the size of the Fe2O3 nanoparticles were analyzed by SEM and XRD. The UV-Vis optical absorption of the samples was also investigated. These methods help to define the obstacles that remain to be surmounted in order to fully exploit the potential of this promising material for solar energy conversion.

Joya, M. R.; Barón-Jaimez, J.; Barba-Ortega, J.

2013-11-01

276

Control of Colloid Surface Chemistry through Matrix Confinement: Facile Preparation of Stable Antibody Functionalized Silver Nanoparticles  

PubMed Central

Here we describe a simple yet efficient gel matrix assisted preparation method which improves synthetic control over the interface between inorganic nanomaterials and biopolymers and yields stable biofunctionalized silver nanoparticles. Covalent functionalization of the noble metal surface is aided by the confinement of polyethylene glycol acetate functionalized silver nanoparticles in thin slabs of a 1% agarose gel. The gel confined nanoparticles can be transferred between reaction and washing media simply by immersing the gel slab in the solution of interest. The agarose matrix retains nanoparticles but is swiftly penetrated by the antibodies of interest. The antibodies are covalently anchored to the nanoparticles using conventional crosslinking strategies, and the resulting antibody functionalized nanoparticles are recovered from the gel through electroelution. We demonstrate the efficacy of this nanoparticle functionalization approach by labeling specific receptors on cellular surfaces with functionalized silver nanoparticles that are stable under physiological conditions.

Skewis, Lynell R.; Reinhard, Bjorn M.

2010-01-01

277

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.

Priyanka, K; Sathali, A Abdul Hasan

2012-01-01

278

Surface study of fine MgFe 2O 4 ferrite powder prepared by chemical methods  

NASA Astrophysics Data System (ADS)

To study surface behaviors, MgFe 2O 4 ferrite materials having different grain sizes were synthesized by two different chemical methods, i.e., a polymerization method and a reverse coprecipitation method. The single phase of the cubic MgFe 2O 4 was confirmed by the X-ray diffraction method for both the precursors decomposed at 600-1000 °C except for a very small peak of Fe 2O 3 was detected for the samples calcined at 600 and 700 °C by the polymerization method. The crystal size and particle size increased with an increase in the sintering temperature using both methods. The conductance of the MgFe 2O 4 decreased when the atmosphere was changed from ambient air to air containing 10.0 ppm NO 2. The conductance change, C = G(air)/ G(10 ppm NO 2), was reduced with an increase in the operating temperature. For the polymerization method, the maximum C-value was ca. 40 at 300 °C for the samples sintered at 900 °C. However, the samples sintered at 1000 °C showed a low conductance change in the 10 ppm NO 2 gas, because the ratio of the O 2 gas adsorption sites on the particle surface is smaller than those of the samples having a high C-value. The low Mg content on the surface affects the low ratio of the gas adsorption sites. For the reverse coprecipitation method, the particle size was smaller than that of the polymerization method. Although a stable conductance was obtained for the sample sintered at 900 and 1000 °C, its conductance change was less than that of the polymerization method.

Aono, Hiromichi; Hirazawa, Hideyuki; Naohara, Takashi; Maehara, Tsunehiro

2008-02-01

279

In situ preparation of monodispersed Ag/polyaniline/Fe3O4 nanoparticles via heterogeneous nucleation  

PubMed Central

Acrylic acid and styrene were polymerized onto monodispersed Fe3O4 nanoparticles using a grafting copolymerization method. Aniline molecules were then bonded onto the Fe3O4 nanoparticles by electrostatic self-assembly and further polymerized to obtain uniform polyaniline/Fe3O4 (PANI/Fe3O4) nanoparticles (approximately 35 nm). Finally, monodispersed Ag/PANI/Fe3O4 nanoparticles were prepared by an in situ reduction reaction between emeraldine PANI and silver nitrate. Fourier transform infrared and UV-visible spectrometers and a transmission electron microscope were used to characterize both the chemical structure and the morphology of the resulting nanoparticles.

2013-01-01

280

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

281

Preparation of monodisperse Co and Fe nanoparticle using precursor of M 2+-oleate 2 (M = Co, Fe)  

Microsoft Academic Search

The preparation of highly crystalline and monodisperse Co and Fe nanoparticle is reported. Co and Fe nanoparticles were prepared by M2+-oleate2 (M=Co and Fe) complex using thermal decomposition method. High-temperature (286°C) reflux of octyl ether solution containing M2+-oleate2 complex under Ar atmosphere generated monodisperse Co and Fe nanoparticles. Particle size of Co nanoparticles and Fe nanoparticles is 13.2±1.9nm and 12.5±1.3nm,

Don Keun Lee; Young Hwan Kim; Xiao-Li Zhang; Young Soo Kang

2006-01-01

282

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.

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

2011-01-01

283

Preparation and evaluation of nimesulide-loaded ethylcellulose and methylcellulose nanoparticles and microparticles for oral delivery.  

PubMed

The present study was designed to assess and compare with a range of surfactant-coated, nimesulide-free, and nimesulide-loaded ethylcellulose/methylcellulose (EC/MC) nanoparticles that were prepared by varying drug concentration (ED/MD), polymer concentration (EP/MP), and surfactant concentration (ES/MS). EC/MC nanoparticles prepared by desolvation method produced discrete particles and they were characterized by SEM, AFM, and FTIR studies. The particles mean size diameter (nm) ranged from 244 to 1056 nm and 1065 to 1710 nm for EC and MC nanoparticles, respectively. Studies on drug: polymer ratio showed a linear relationship between drug concentration and percentage of loading in nanoparticles. The encapsulation efficiency decreased with the increase of nimesulide concentration with respect to polymer concentration. Encapsulation efficiency of drug-loaded nanoparticles was varied between 32.8% and 64.9%. The in vitro release of drug-loaded nanoparticles was found to be a first order. This was significantly increased in EC nanoparticles (95.50%) in comparison with MC nanoparticles (95.12%) after 12 h in 24 h long study. Nimesulide release from EC nanoparticles was much slower at slightly alkaline pH 7.4. The in vitro hemolysis tests of nanoparticles were carried out to ascertain the hemocompatibility and shown to be insignificant for EC nanoparticles. In comparison, ES4 from EC formulations with nimesulide was found to be promising with slow and sustained drug release. PMID:19386664

Ravikumara, N R; Madhusudhan, B; Nagaraj, T S; Hiremat, Shobarani R; Raina, Gargi

2009-07-01

284

Preparation and characterization of Paliperidone loaded solid lipid nanoparticles.  

PubMed

Solid lipid nanoparticles were prepared and studied for the possibility of entrapment of Paliperidone (PPN) an antipsychotic drug that can be used for the treatment of schizophrenia. Here we report the preparation of Paliperidone loaded solid lipid particles (SLNs) with Capmul GMS 50 K as lipid vehicle. SLNs were stabilized by a surfactant namely sodium deoxycholate which can also act as permeability enhancer. Final size of SLNs produced were approximately 200 nm which was confirmed by dynamic light scattering (DLS), atomic force microscopy (AFM) and transmission electron microscopy (TEM). SLNs appeared spherical in TEM images while dough nut like shape was observed by AFM. The entrapment efficiency of this system was found to be 55% with 4.15% of drug loading in lipid matrix. Structural characterization of SLNs by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD) and differential scanning calorimetric (DSC) analysis revealed that, there was no interaction of PPN with lipid and PPN was well dispersed in the lipid matrix without any crystallization. PMID:23104026

Kumar, Sacheen; Randhawa, Jaspreet Kaur

2013-02-01

285

Janus nanoparticles: materials, preparation and recent advances in drug delivery.  

PubMed

Introduction: The term Janus particles was used to describe particles that are the combination of two distinct sides with differences in chemical nature and/or polarity on each face. Due to the exponential growth of interest on multifunctional nanotechnologies, such anisotropic nanoparticles are promising tools in the field of drug delivery. Areas covered: The main preparation processes and the materials used have been described first. Then a specific focus has been done on therapeutic and/or diagnostic applications of Janus particles. Expert opinion: Janus particles are demonstrated as interesting objects with advanced properties that combine features and functionalities of different materials in one single unit. Due to their dual structure, Janus particles are promising candidates for a variety of high-quality applications dealing with drug delivery purposes. Still, the main challenges for the future lie in the development of the preparation of shape-controlled and nano-sized particles with large-scale production processes and approved pharmaceutical excipients. PMID:24811771

Tran, Le-Tuyet-Chau; Lesieur, Sylviane; Faivre, Vincent

2014-07-01

286

Preparation and characterization of triclosan nanoparticles for periodontal treatment.  

PubMed

The aim of this work was to produce and characterize triclosan-loaded nanoparticles (NPs) by the emulsification-diffusion process, in an attempt to obtain a novel delivery system adequate for the treatment of periodontal disease. The NPs were prepared using poly(D,L-lactide-co-glycolide) (PLGA), poly(D,L-lactide) (PLA) and cellulose acetate phthalate (CAP). Poly(vinyl alcohol) (PVAL) was used as stabilizer. Batches were prepared with different amounts of triclosan (TCS) in order to evaluate the influence of drug on NP properties. Solid NPs of less than 500 nm in diameter were obtained. Entrapment efficiencies were higher than 63.8%. The characterization by scanning electron microscopy and light scattering indicated that high concentrations of TCS seemingly caused the increase of NP mean size. A decrease in the PLGA glass transition temperature was observed by differential scanning calorimetry. This could indicate that TCS in PLGA-NPs behaves as a non-conventional plasticizer. Subsequently, in vitro release studies were carried out under sink conditions using a device designed in our laboratory to allow a direct contact between the particles and the dissolution medium. A fast release of TCS from NPs was detected. A preliminary in vivo study in dogs with induced periodontal defects suggested that TCS-loaded NPs penetrate through the junctional epithelium. PMID:15814246

Piñón-Segundo, E; Ganem-Quintanar, A; Alonso-Pérez, V; Quintanar-Guerrero, D

2005-04-27

287

Conjugated polymer nanoparticles: preparation, properties, functionalization and biological applications.  

PubMed

In the past few years, conjugated polymer nanoparticles (CPNs) have been successfully prepared and applied in the biological field because of their unique opto-electronic properties. The rapid development of CPNs is mainly attributed to their simple synthesis procedures and easy separation steps. The advantages of CPNs include high brightness, excellent photostability, low cytotoxicity, high quantum yield and versatile surface modification. The functionalization of CPNs with specific recognition elements imparts them good ability for targeted recognition and imaging in vitro and in vivo. CPNs can be applied to deliver drug and gene, and simultaneously to real-time monitor the release process due to their self-luminous characteristics. Moreover, CPNs can sensitize oxygen molecules to generate reactive oxygen species (ROS) which can kill adjacent bacteria and tumor cells. In this tutorial review, we provide a recent development of the preparation methods, properties, and functionalization strategies of CPNs, especially discussing their biological applications in targeted imaging, drug/gene delivery and biomedicine. The challenges and outlooks in this field will also be discussed. PMID:23744297

Feng, Liheng; Zhu, Chunlei; Yuan, Huanxiang; Liu, Libing; Lv, Fengting; Wang, Shu

2013-08-21

288

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

289

Preparation, characterization and antibacterial properties against E. coli K88 of chitosan nanoparticle loaded copper ions  

NASA Astrophysics Data System (ADS)

The present study was conducted to prepare and characterize chitosan nanoparticle loaded copper ions, and evaluate their antibacterial activity. Chitosan nanoparticles were prepared based on ionotropic gelation, and then the copper ions were loaded. The particle size, zeta potential and morphology were determined. Antibacterial activity was evaluated against E. coli K88 by determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in vitro. Results showed that the antibacterial activity was significantly enhanced by the loading of copper ions compared to those of chitosan nanoparticles and copper ions. The MIC and MBC of chitosan nanoparticle loaded copper ions were 21 times and 42 times lower than those of copper ions, respectively. To confirm the antibacterial mechanism, morphological changes of E. coli K88 treated by chitosan nanoparticle loaded copper ions were dynamically observed with an atomic force microscope (AFM). It was found that chitosan nanoparticle loaded copper ions killed E. coli K88 through damage to the cell membrane.

Du, Wen-Li; Xu, Ying-Lei; Xu, Zi-Rong; Fan, Cheng-Li

2008-02-01

290

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

291

The morphology of silver nanoparticles prepared by enzyme-induced reduction  

PubMed Central

Summary Silver nanoparticles were synthesized by an enzyme-induced growth process on solid substrates. In order to customize the enzymatically grown nanoparticles (EGNP) for analytical applications in biomolecular research, a detailed study was carried out concerning the time evolution of the formation of the silver nanoparticles, their morphology, and their chemical composition. Therefore, silver-nanoparticle films of different densities were investigated by using scanning as well as transmission electron microscopy to examine their structure. Cross sections of silver nanoparticles, prepared for analysis by transmission electron microscopy were additionally studied by energy-dispersive X-ray spectroscopy in order to probe their chemical composition. The surface coverage of substrates with silver nanoparticles and the maximum particle height were determined by Rutherford backscattering spectroscopy. Variations in the silver-nanoparticle films depending on the conditions during synthesis were observed. After an initial growth state the silver nanoparticles exhibit the so-called desert-rose or nanoflower-like structure. This complex nanoparticle structure is in clear contrast to the auto-catalytically grown spherical particles, which maintain their overall geometrical appearance while increasing their diameter. It is shown, that the desert-rose-like silver nanoparticles consist of single-crystalline plates of pure silver. The surface-enhanced Raman spectroscopic (SERS) activity of the EGNP structures is promising due to the exceptionally rough surface structure of the silver nanoparticles. SERS measurements of the vitamin riboflavin incubated on the silver nanoparticles are shown as an exemplary application for quantitative analysis.

Schuler, Thomas; Strelau, Katharina K; Weber, Karina; Cialla, Dana; Diegel, Marco; Mattheis, Roland; Berger, Andreas; Moller, Robert; Popp, Jurgen

2012-01-01

292

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

293

Preparation of silver nanoparticles in the presence of chitosan by electrochemical method.  

PubMed

The present study involves the development of stabilized and densely dispersed chitosan-silver nanoparticles using a green approach based on electrochemical oxidation/complexation process followed by UV irradiation reduction. Formation of the nanoparticles was confirmed by appearance of surface plasmon absorption around 420 nm. The nanoparticles were characterized using transmission electron microscopy, X-ray diffraction, elemental analysis, atomic absorption, energy dispersive X-ray, Fourier transform infrared, and UV-Visible spectrophotometry. The obtained nanoparticles were uniform and spherical with average size of 2-16 nm. It was found that increasing the Ag content in the chitosan-Ag based films tends to decrease their equilibrium swelling values. The nanoparticles also demonstrated a relatively high antibacterial activity against Bacillus thuringiensis and Pseudomonas aeruginosa bacteria as compared to that of chitosan and the antibacterial activity increased with increasing the nanoparticle concentration. The obtained results revealed that the prepared nanoparticles could be tailored and used in various biomedical applications. PMID:24750629

Reicha, Fikry M; Sarhan, Afaf; Abdel-Hamid, Maysa I; El-Sherbiny, Ibrahim M

2012-06-01

294

A highly efficient phase transfer method for preparing alkylamine-stabilized Ru, Pt, and Au nanoparticles  

Microsoft Academic Search

A highly efficient phase-transfer method was developed to prepare alkylamine-stabilized nanoparticles of several noble metals. This method involved first mixing the metal hydrosols and an ethanol solution of dodecylamine and then extracting the dodecylamine-stabilized metal nanoparticles into toluene. The efficiency of this phase-transfer method was nearly 100%. Alkylamine-stabilized Ru, Pt, and Au nanoparticles 3.45, 4.33, and 7.89 nm in diameter, respectively,

J Yang; Jim Yang Lee; T. C Deivaraj; Heng-Phon Too

2004-01-01

295

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

296

Preparation of polystyrene grafted silica nanoparticles by two-steps UV induced reaction  

Microsoft Academic Search

Polystyrene grafted silica nanoparticles (PSSNs) were prepared by the followed two steps: methacryloxypropyl silica nanoparticles (MPSNs) were modified with the monomer-iniferter, 4-vinylbenzyl N,N-diethyldithiocarbamate (VBDC) under UV irradiation. Then the VBDC modified silica nanoparticles (VBDCSNs) were used as iniferter for the surface-initiated (SI) controlled\\/“living” radical polymerization of styrene. A percentage of grafting (PG%) of 315.7% was achieved with a conversion of

Peng Liu; Zhixing Su

2004-01-01

297

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.

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

2012-01-01

298

Encapsulation of BSA in polylactic acid–hyperbranched polyglycerol conjugate nanoparticles: preparation, characterization, and release kinetics  

Microsoft Academic Search

Nanoparticles based on an amphiphilic copolymer with polylactic acid (PLA) grafted onto hyperbranched polyglycerol (HPG) were\\u000a prepared by the use of BSA as a model protein. The characteristics of the nanoparticles were evaluated using particle size\\u000a analyzer, transmission electron microscopy, and X-ray photoelectron spectroscopy. The secondary structure of BSA released\\u000a from nanoparticles were analysed by circular dichroism experiments. Cell viability

Xiujun Gao; Xinge Zhang; Xuejiao Zhang; Cui Cheng; Zhen Wang; Chaoxing Li

2010-01-01

299

Control of Particle Size and Morphology of Cobalt-Ferrite Nanoparticles by Salt-Matrix during Annealing  

NASA Astrophysics Data System (ADS)

Salt-matrix annealing of mechanically alloyed Co-ferrite nanopowder was used to modify its particle size and morphology. Efficiency improvement due to suppression of sintering and growth resulted in reduction of average particle size from 100nm for salt-less to 40nm for salt-full annealing procedure. Nanosized single-phase cobalt-ferrite particles were observed after 2h annealing at 750°C in the samples milled for 20 hours both with and without NaCl. NaCl:CoFe2O4 ratio of 10:1 resulted in cabbage-like clusters containing particles smaller than 50 nm.

Azizi, A.; Sadrnezhaad, S. K.; Mostafavi, M.

300

Alkyl-terminated crystalline Ge nanoparticles prepared from NaGe: Synthesis, functionalization and optical properties  

NASA Astrophysics Data System (ADS)

High purity NaGe was directly prepared by a low-temperature reaction of NaH and Ge. The product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. This material is a useful starting reagent for the preparation of Ge nanoparticles. Hydrogen-terminated germanium (Ge) nanoparticles were prepared by reaction of NaGe with NH 4Br. These Ge nanoparticles could be prepared as amorphous or crystalline nanoparticles in quantitative yields and with a narrow size distribution. The nanoparticles were functionalized via thermally initiated hydrogermylation with 1-eicosyne, CH 3(CH 2) 17C?CH to produce alkyl-terminated Ge nanoparticles. The modified Ge nanoparticles were characterized by powder XRD, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) and Raman spectroscopy, and photoluminescence (PL) spectroscopy. The alkyl-functionalized Ge nanoparticles can be expected to have promising applications in many technological and biological areas.

Ma, Xuchu; Wu, Fengyi; Kauzlarich, Susan M.

2008-07-01

301

Preparation and Magnetic Properties of Fe and Ni Based Nanoparticles and Nanowires  

Microsoft Academic Search

In this work we present our experimental results on the preparation and magnetic properties of iron and nickel based nanoparticles and nanowires. Fe, Ni and Ni-Fe nanoparticles have been synthesized by polyol method and Ni-Fe nanowire arrays have been synthesized by electrochemical deposition. The morphology and sizes of synthesised nanostructures were studied by scanning electron microscopy (SEM), atomic force microscopy

H. Chiriac; A. E. Moga; C. Gherasimu

2006-01-01

302

Preparation, Structure, and Properties of Magnetic Materials Based on Co-Containing Nanoparticles  

Microsoft Academic Search

The recent experimental data on the preparation and properties of materials containing Co-based magnetic nanoparticles are summarized. Particular attention is focused on the synthesis of cobalt nanoparticles in “rigid” matrices (polymers, metals, and solid surfaces) and their static magnetic properties, which are of great importance for practical applications. The conclusion is made that surface effects play an important role in

S. P. Gubin; Yu. A. Koksharov

2002-01-01

303

Magnetic lipid nanoparticles loading doxorubicin for intracellular delivery: Preparation and characteristics  

Microsoft Academic Search

Tumor intracellular delivery is an effective route for targeting chemotherapy to enhance the curative effect and minimize the side effect of a drug. In this study, the magnetic lipid nanoparticles with an uptake ability by tumor cells were prepared dispersing ferroso-ferric oxide nanoparticles in aqueous phase using oleic acid (OA) as a dispersant, and following the solvent dispersion of lipid

Xiao-Ying Ying; Yong-Zhong Du; Ling-Hong Hong; Hong Yuan; Fu-Qiang Hu

2011-01-01

304

Design of rolipram-loaded nanoparticles: comparison of two preparation methods  

Microsoft Academic Search

The aim of the present work was to investigate the preparation of nanoparticles as a potential drug carrier and targeting system for the treatment of inflammatory bowel disease. Rolipram was chosen as the model drug to be incorporated within nanoparticles. Pressure homogenization–emulsification (PHE) with a microfluidizer or a modified spontaneous emulsification solvent diffusion method (SESD) were used in order to

Alf Lamprecht; Nathalie Ubrich; Hiromitsu Yamamoto; Ulrich Schäfer; Hirofumi Takeuchi; Claus-Michael Lehr; Philippe Maincent; Yoshiaki Kawashima

2001-01-01

305

Synthesis and optical properties of copper nanoparticles prepared by a chemical reduction method  

Microsoft Academic Search

Copper nanoparticles, due to their interesting properties, low cost preparation and many potential applications in catalysis, cooling fluid or conductive inks, have attracted a lot of interest in recent years. In this study, copper nanoparticles were synthesized through the chemical reduction of copper sulfate with sodium borohydride in water without inert gas protection. In our synthesis route, ascorbic acid (natural

Thi My Dung Dang; Thi Tuyet Thu Le; Eric Fribourg-Blanc; Mau Chien Dang

2011-01-01

306

Nanoaggregates of a pentacenequinone derivative as reactors for the preparation of palladium nanoparticles.  

PubMed

Fluorescent nanoaggregates of pentacenequinone derivative serve as reactors for the preparation of palladium nanoparticles in aqueous medium. Further, the combination of catalytic quantities of palladium nanoparticles with NaBH(4) smoothly reduces 4-nitrophenol to 4-aminophenol in aqueous medium. PMID:23042509

Bhalla, Vandana; Gupta, Ankush; Kumar, Manoj

2012-12-18

307

Preparation of primary amine-modified gold nanoparticles and their transfection ability into cultivated cells.  

PubMed

Cationic gold nanoparticles, prepared by reducing HAuCl(4) with NaBH(4) in the presence of 2-aminoethanethiol, formed a complex with plasmid DNA, and could be transfected into cultivated cells. PMID:15340630

Niidome, Takuro; Nakashima, Kanako; Takahashi, Hironobu; Niidome, Yasuro

2004-09-01

308

Strategy for preparation of hybrid polymer hydrogels using silica nanoparticles as multifunctional crosslinking points.  

PubMed

Novel hybrid polymer hydrogels were prepared in a facile manner by simple mixing of a water-soluble copolymer having trimethoxysilyl side chains with silica nanoparticles used as multiple crosslinkers. PMID:21069222

Takafuji, Makoto; Yamada, Shin-ya; Ihara, Hirotaka

2011-01-21

309

Photochemical preparation of silver nanoparticles supported on zeolite crystals.  

PubMed

A facile and rapid photochemical method for preparing supported silver nanoparticles (Ag-NPs) in a suspension of faujasite type (FAU) zeolite nanocrystals is described. Silver cations are introduced by ion exchange into the zeolite and subsequently irradiated with a Xe-Hg lamp (200 W) in the presence of a photoactive reducing agent (2-hydroxy-2-methylpropiophenone). UV-vis characterization indicates that irradiation time and intensity (I0) influence significantly the amount of silver cations reduced. The full reduction of silver cations takes place after 60 s of a polychromatic irradiation, and a plasmon band of Ag-NPs appears at 380 nm. Transmission electron microscopy combined with theoretical calculation of the plasmon absorbance band using Mie theory shows that the Ag-NPs, stabilized in the micropores and on the external surface of the FAU zeolite nanocrystals, have an almost spheroidal shape with diameters of 0.75 and 1.12 nm, respectively. Ag-NPs, with a homogeneous distribution of size and morphology, embedded in a suspension of FAU zeolites are very stable (?8 months), even without stabilizers or capping agents. PMID:24810992

Zaarour, Moussa; El Roz, Mohamad; Dong, Biao; Retoux, Richard; Aad, Roy; Cardin, Julien; Dufour, Christian; Gourbilleau, Fabrice; Gilson, Jean-Pierre; Mintova, Svetlana

2014-06-01

310

Preparation and characterization of nocodazole-loaded solid lipid nanoparticles.  

PubMed

Nocodazole (NCD) has more carcinogenic effect than similar drugs. Moreover, it has low drug release time and high particle size. Solid Lipid Nanoparticles (SLNs) have been evaluated for decrease in particle size and therefore increase in drug release time, for such drugs. In this study, NCD has been successfully incorporated into SLNs systems and remained stable for a period of 90 days. NCD structure related to the chemical nature of solid lipid is a key factor to decide whether anticarcinogenic agent will be incorporated in the long term and for a controlled optimization of active ingredient incorporation and loading, intensive characterization of the physical state of the lipid particles were highly essential. Thus, NMR, FT-IR, DSC (for thermal behavior) analyses were performed and the results did not indicate any problem on stability. Moreover, SLNs were decreased size of NCD in addition to increase in time of the drug release. After SLN preparation, particle size, polydispersity index, electrical conductivity and zeta potential were measured and drug release from NCD-loaded SLNs were performed. These values seem to be of the desired range. PMID:23869451

Genç, Lütfi

2014-09-01

311

Preparation of Polydiacetylene-Attached TiO2 Nanoparticles  

Microsoft Academic Search

Polydiacetylene-attached titania nanoparticles were synthesized by the reaction with 10,12-pentacosadiynoic acid (PDA). The surface of titania nanoparticles was modified with a silane coupling agent, 3-aminopropyltrimethoxy silane (APTMS). 10,12-Pentacosadiynoic acid (PDA) was also modified by the esterification of N-hydroxy-succinimide (HS) with 4-pyrrolidinopyridine as a catalyst. The modified PDA (HS-PDA) was attached to titania by the reaction between modified TiO2nanoparticles and HS-PDA.

Yong Ku Kwon; Jin Mi Jung; Kwang Hee Lee

2007-01-01

312

Zirconia nanoparticles prepared by laser vaporization as fillers for dental adhesives  

Microsoft Academic Search

Zirconia nanoparticles prepared by laser vaporization were incorporated into the primer or into the adhesive of a commercial adhesive system in order to evaluate its effect on bond strength to dentin. Zirconia nanoparticles (20–50nm) were prepared using a particular laser vaporization technique and incorporated into the primer (P) or into the adhesive (A) of the Adper Scotchbond Multi-Purpose (SBMP) system

Ulrich Lohbauer; Andrea Wagner; Renan Belli; Christian Stoetzel; Andrea Hilpert; Heinz-Dieter Kurland; Janet Grabow; Frank A. Müller

2010-01-01

313

Preparation of hollow capsule-stabilized gold nanoparticles through the encapsulation of the dendrimer  

Microsoft Academic Search

The narrow-dispersed dendrimer-encapsulated gold nanoparticles without agglomeration were prepared from the grafted-dendrimers on the surface of the silica microspheres, successively by complexation of the gold chloride anion with the nitrogen atom of the dendrimer and the reduction with sodium borohydride as reductant. The hollow capsule-stabilized gold nanoparticles were prepared through the encapsulation of dendrimer successively by LBL self-assembly process of

Hongying Wu; Zelin Liu; Xudong Wang; Baohui Zhao; Jian Zhang; Chenxi Li

2006-01-01

314

Preparation of hydrophobic gold nanoparticles with safe organic solvents by microwave irradiation method  

Microsoft Academic Search

A safe organic solvent mixture n-heptane\\/ethanol was used as dispersion medium in reversal micelle to replace the commonly used toxic and highly volatile organic solvent such as chloroform and other solvents. This method overcame the obstacle for preparing hydrophobic nanoparticles by microwave irradiation method. The hydrophobic gold nanoparticles capped with octadecylamine (C18NH2) were prepared by using ethanol reduction in reverse

Ming Shen; Yu-kou Du; Hui-lin Rong; Jin-ru Li; Long Jiang

2005-01-01

315

General preparation for Pt-based alloy nanoporous nanoparticles as potential nanocatalysts  

PubMed Central

Although Raney nickel made by dealloying has been used as a heterogeneous catalyst in a variety of organic syntheses for more than 80 years, only recently scientists have begun to realize that dealloying can generate nanoporous alloys with extraordinary structural characteristics. Herein, we achieved successful synthesis of a variety of monodisperse alloy nanoporous nanoparticles via a facile chemical dealloying process using nanocrystalline alloys as precursors. The as-prepared alloy nanoporous nanoparticles with large surface area and small pores show superior catalytic properties compared with alloyed nanoparticles. It is believed that these novel alloy nanoporous nanoparticles would open up new opportunities for catalytic applications.

Wang, Dingsheng; Zhao, Peng; Li, Yadong

2011-01-01

316

Preparation of palladium nanoparticles–titanium electrodes as a new anode for direct methanol fuel cells  

Microsoft Academic Search

Pd nanoparticle\\/Ti electrodes are prepared by electroless plating of palladium on titanium plates. The morphology and surface\\u000a analysis of Pd nanoparticle\\/Ti electrodes are investigated using scanning electron microscopy and energy-dispersive X-ray\\u000a spectroscopy, respectively. The results indicate that palladium nanoparticles are homogeneously deposited on the surface of\\u000a titanium plates. The electro-catalytic activity of Pd nanoparticle\\/Ti electrodes in the methanol electro-oxidation is

Javad Hosseini; Ali Bodaghi

2011-01-01

317

Oriented Y-type hexagonal ferrite thin films prepared by chemical solution deposition  

NASA Astrophysics Data System (ADS)

Thin films of Ba2Zn2Fe12O22 (Y) hexaferrite were prepared through the chemical solution deposition method on SrTiO3(1 1 1) (ST) single crystal substrates using epitaxial SrFe12O19 (M) hexaferrite thin layer as a seed template layer. The process of crystallization was mainly investigated by means of X-ray diffraction and atomic force microscopy. A detailed inspection revealed that growth of seed layer starts through the break-up of initially continuous film into isolated grains with expressive shape anisotropy and hexagonal habit. The vital parameters of the seed layer, i.e. thickness, substrate coverage, crystallization conditions and temperature ramp were optimized with the aim to obtain epitaxially crystallized Y phase. X-ray diffraction Pole figure measurements and ? scans reveal perfect parallel in-plane alignment of SrTiO3 substrate and both hexaferrite phases.

Buršík, J.; Kužel, R.; Knížek, K.; Drbohlav, I.

2013-07-01

318

Preparation and properties of bio-compatible magnetic Fe 3O 4 nanoparticles  

NASA Astrophysics Data System (ADS)

In this work, we study the preparation and properties of bio-compatible magnetic nanoparticles for immunoassay and DNA detection. The magnetite (Fe 3O 4) nanoparticles were prepared by a chemical co-precipitation method and dextran was selected as the surfactant to suspend the nanoparticles. Suspended particles associated with avidin followed by biotin were qualitatively analyzed by enzyme-linked immunosorbent assay (ELISA) method. We found further the ethylenediamine blocked activated residual groups efficiently, hence enhancing the attachment of biotin for probing the avidin.

Chan, H. T.; Do, Y. Y.; Huang, P. L.; Chien, P. L.; Chan, T. S.; Liu, R. S.; Huang, C. Y.; Yang, S. Y.; Horng, H. E.

2006-09-01

319

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

320

[Preparation of superparamagnetic paclitaxel nanoparticles from modified chitosan and their cytotoxicity against malignant brain glioma].  

PubMed

We synthesized the superparamagnetic paclitaxel nanoparticles from modified chitosan tangling around Fe3O4 ferrofluid and taxol, and observed the nanoparticles with transmission electronic microscopy (TEM). Then we evaluated the paramagnetism of the particles by vibration specimen magnetometer (VSM) and tested their cytotoxicity with flow cytometry (FCM). The prepared nanoparticle solution was black without any floccule or sediment and appeared transparent after diluted. The nanoparticles were spherical and dispersed in water with mean diameter of 15 nm under TEM and showed superparamagnetic character. FCM test showed the nanoparticles had significant toxic effects against malignant astrocytoma U251 cell lines, equal to taxol alone. These results showed that the superparamagnetic nanoparticle not only enhanced the solubility of paclitaxel in water, but also was superparamagnetic and cytotoxic, which make suitable tools for magnetic targeting chemotherapy of brain gliomas. PMID:21774213

Zhao, Ming; Li, Anmin; Chang, Jin; Wang, Hanjie; Liang, Shuli; Zhang, Jiajing; Yan, Runmin

2011-06-01

321

Artesunate-loaded chitosan/lecithin nanoparticles: preparation, characterization, and in vivo studies.  

PubMed

Artesunate (AST), the most widely used artemisnin derivative, has poor aqueous solubility and suffers from low oral bioavailability (~40%). Under these conditions, nanoparticles with controlled and sustained released properties can be a suitable solution for improving its biopharmaceuticals properties. This work reports the preparation and characterization of auto-assembled chitosan/lecithin nanoparticles loaded with AST and AST complexed with ?-cyclodextrin (?-CD) to boost its antimalarial activity. The nanoparticles prepared by direct injection of lecithin alcoholic solution into chitosan/water solution have shown the particle size distribution below 300?nm. Drug entrapment efficiency was found to be maximum (90%) for nanoparticles containing 100?mg of AST. Transmission electron microscopy images show spherical shape with contrasted corona (chitosan) surrounded by a lipidic core (lecithin + isopropyl myristate). Differential scanning calorimeter thermograms demonstrated the presence of drug in drug-loaded nanoparticles along with the disappearance of decomposition exotherm suggesting the increased physical stability of drug in prepared formulations. Negligible changes in the characteristic peaks of drug in Fourier-transform infrared spectra indicated the absence of any interaction among the various components entrapped in the nanoparticle formulation. In vitro drug release behavior was found to be influenced by pH value. Increased in vivo antimalarial activity in terms of less mean percent parasitemia was observed in infected Plasmodium berghei mice after the oral administration of all the prepared nanoparticle formulations. PMID:22348223

Chadha, Renu; Gupta, Sushma; Pathak, Natasha

2012-12-01

322

Synthesis and characterizations of ferrite nanomaterials for phenyl hydrazine chemical sensor applications.  

PubMed

This paper presents the synthesis, characterization and phenyl hydrazine chemical sensing applications of Cd0.5Mg0.5Fe2O4 ferrite nanoparticles. The nanoparticles were synthesized by facile and simple co-precipitation method and characterized in detail in terms of their morphological, structural, compositional and electrical properties. The detailed characterization studies revealed that the prepared nanoparticles are grown in high density, possessing Cd0.5Mg0.5Fe2O4 composition and exhibiting spinel cubic structure. Moreover, the prepared Cd0.5Mg0.5Fe2O4 ferrite nanoparticles were used as efficient electron mediators for the fabrication of high-sensitive, robust, reliable and reproducible phenyl hydrazine chemical sensor by simple I-V technique. The fabricated chemical sensor exhibits a highsensitivity of 7.01 microA mM(-1) cm(-2) with an experimental detection limit of 3.125 mM in a short response time of -10.0 s. This work demonstrates that Cd0.5Mg0.5Fe2O4 ferrite nanoparticles can efficiently be utilized for the fabrication of highly sensitive and reliable chemical sensors. PMID:24734630

Al-Heniti, S H; Umar, Ahmad; Zaki, H M; Dar, G N; Al-Ghamdi, A A; Kim, S H

2014-05-01

323

Phase Control of Ti--Fe Nanoparticles Prepared by Pulsed Wire Discharge  

NASA Astrophysics Data System (ADS)

Ti--Fe nanoparticles were prepared by pulsed wire discharge (PWD) using iron (Fe) and titanium (Ti) twisted wire in Ar gas at a pressure of 100 kPa. The content of Fe (CFe), which was changed from 0 to 100 wt %, was controlled by adjusting the number of Ti and Fe wires in the twisted wire. From the X-ray diffraction, the phase of the prepared nanoparticles changed from ?-Ti to ?-Ti, FeTi, Fe2Ti, Fe(Ti), and Fe with increasing CFe. FeTi nanoparticles were obtained at approximately CFe = 30 wt %. From these results, the phases of the prepared Ti--Fe nanoparticles were controlled by adjusting the content of Fe in the twisted wire.

Tokoi, Yoshinori; Orikawa, Takuya; Suzuki, Tsuneo; Nakayama, Tadachika; Suematsu, Hisayuki; Niihara, Koichi

2011-01-01

324

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

325

[Preparation of polyelectrolyte microcapsules containing ferrosoferric oxide nanoparticles].  

PubMed

In this study, polyelectrolyte microcapsules have been fabricated by biocompatible ferrosoferric oxide nanoparticles (Fe3O4 NPs) and poly allyamine hydrochloride (PAH) using layer by layer assembly technique. The Fe3O4 NPs were prepared by chemical co-precipitation, and characterized by transmission electron microscopy (TEM) and infrared spectrum (IR). Quartz cell also was used as a substrate for building multilayer films to evaluate the capability of forming planar film. The result showed that Fe3O4 NPs were selectively deposited on the surface of quartz cell. Microcapsules containing Fe3O4 NPs were fabricated by Fe3O4 NPs and PAH alternately self-assembly on calcium carbonate microparticles firstly, then 0.2 molL(-1) EDTA was used to remove the calcium carbonate. Scanning electron microscopy (SEM), Zetasizer and vibrating sample magnetometer (VSM) were used to characterize the microcapsule's morphology, size and magnetic properties. The result revealed that Fe3O4 NPs and PAH were successfully deposited on the surface of CaCO3 microparticles, the microcapsule manifested superparamagnetism, size and saturation magnetization were 4.9 +/- 1.2 microm and 8.94 emu x g(-1), respectively. As a model drug, Rhodamin B isothiocyanate labeled bovine serum albumin (RBITC-BSA) was encapsulated in microcapsule depended on pH sensitive of the microcapsule film. When pH 5.0, drug add in was 2 mg, the encapsulation efficiency was (86.08 +/- 3.36) % and the drug loading was 8.01 +/- 0.30 mg x m(L-1). PMID:21465817

Liu, Xiao-Qing; Zheng, Chun-Li; Zhu, Jia-Bi

2011-01-01

326

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.

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

2010-01-01

327

Sol-gel derived nanoparticles of Zn substituted lithium ferrite (Li 0.32Zn 0.36Fe 2.32O 4): magnetic and Mössbauer effect measurements and their theoretical analysis  

NASA Astrophysics Data System (ADS)

Nanoparticles of Zn substituted lithium ferrite (Li 0.32Zn 0.36Fe 2.32O 4) have been prepared by a sol-gel method where the ultra-sonication technique has been adopted to reduce the agglomeration effect among the nanoparticles. The samples were heat-treated at three different temperatures and the formation of the nanocrystalline phase was confirmed by X-ray diffractograms (XRD). The average particle size of each sample has been estimated from the (311) peak of the XRD pattern using the Debye-Scherrer formula and the average sizes are in the range of 10-21 nm. The average particle size, crystallographic phase, etc. of some selected samples obtained from the high-resolution transmission electron microscopy are in agreement with those estimated from the XRD patterns. Static magnetic measurements viz., hysteresis loops, field cooled and zero field cooled magnetization versus temperature curves of some samples carried out by SQUID in the temperature range of 300 to 5 K clearly indicate the presence of superparamagnetic (SPM) relaxation of the nanoparticles in the samples. The maximum magnetization of the SPM sample annealed at 500 °C is quite high (68 Am 2/Kg) and the hysteresis loops are almost square shaped with very low value of coercive field at room temperature (827.8 A/m). The particle size, magneto-crystalline anisotropy, etc. have been estimated from the detailed theoretical analysis of the static magnetic data. The dynamic magnetic behavior of the samples was also investigated by observing the ac hysteresis loops and magnetization versus field curves with different time windows at room temperatures. The different soft magnetic quantities viz., coercive field, magnetization, remanance, hysteresis losses, etc. were extracted from dynamic measurements. Dynamic measurements confirmed that the samples are in their mixed state of SPM and ordered ferrimagnetic particles, which is in good agreement with the results of static magnetic measurements. Mössbauer spectra of the samples recorded at room temperature (300 K) and at different temperatures down to 20 K confirmed the presence of the SPM relaxation of the nanoparticles of the samples.

Sutradhar, S.; Pati, S.; Acharya, S.; Das, S.; Das, D.; Chakrabarti, P. K.

2012-04-01

328

Preparation of pure iron/Ni-Zn ferrite high strength soft magnetic composite by spark plasma sintering  

NASA Astrophysics Data System (ADS)

A dense microcellular structure is fabricated using micron-sized pure iron powder cladded with 10 wt% Zn0.5Ni0.5Fe2O4 nanopowder by filling the pure iron with Ni-Zn-ferrites composite and subjecting the mixture to a temperature of 600 °C. The SEM image shows that the thickness of cell wall is in the range of 1.0-2.0 ?m, and the inner dimension of the alloy is in the range of 15-40 ?m. By coating Ni-Zn-ferrites, the electrical resistivity is increased. The composite exhibits not only good soft magnetic properties but also good mechanical strength.

Wang, Minggang; Zan, Zhao; Deng, Na; Zhao, Zhankui

2014-06-01

329

Magnetic properties of Co-ferrite thin films prepared by PLD with in situ heating and post-annealing  

NASA Astrophysics Data System (ADS)

Co-ferrite thin films on (1 0 0) SiO 2 substrates were deposited using pulsed laser deposition with in situ heating and post-annealing heat treatments. The structure and magnetic properties of the films were analyzed by X-ray diffractionmetry, atomic force microscopy, transmission electron microscopy, Raman spectroscopy and alternating gradient force magnetometry. High perpendicular coercivity around 8.9 kOe has been obtained in the film with in situ substrate heating at 700 °C. High coercivity of Co-ferrite thin film was found to be related to nanocystalline grain size, large lattice strain, surface roughness and preferential texture structure.

Yin, J. H.; Ding, J.; Chen, J. S.; Miao, X. S.

2006-08-01

330

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

331

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

332

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.

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

2011-01-01

333

Preparation and Characterization of FeCo Alloy Nanoparticles  

Microsoft Academic Search

FeCo alloy nanoparticles were synthesized by a new reduction process in liquid phase with sodium borohydride and L-ascorbic acid as reductant, and cetyltrimethylammonium bromide as surfactant. The structure and magnetic properties of the samples were investigated by laser particle size analyzer, X-ray powder diffraction, transmission electron microscopy, selected-area electron diffraction and vibrating sample magnetometer. The nanoparticles obtained are nearly spherical

Fengping Wang; Xinghua Xue; Guizhen Wang; Jingyao Cai; Xin Fu

2011-01-01

334

Sonochemical preparation of hydroxyapatite nanoparticles stabilized by glycosaminoglycans.  

PubMed

Stable hydroxyapatite (HAP) nanoparticles system was synthesized from Ca(H(2)PO(4))(2) aqueous solution and saturated Ca(OH)(2) aqueous solution by an improved precipitation method. This method was reformed through using ultrasound irradiation as assistant technology due to its unique chemical reaction effects and adding glycosaminoglycans (GAGs) as regulation additive due to its strong interaction with HAP. The products were characterized by Malvern Zetasizer 3000HS Analysis system, TEM and ED. The size distribution and zeta potential of HAP nanoparticles were influenced by the concentration of GAGs. With the GAGs concentration of 0.35g/L, the better excellent HAP nanoparticle system could be obtained with the number-averaged particle size of 22.2nm in 84.5% area and 54.6nm in 15.5% area between 18.1nm and 117.4nm and the zeta potential of -60.9mV. In the presence of GAGs, the particle size and size distribution are little sensitive to the ultrasound irradiation (UI) time. With the increasing of UI time from 0.5h to 3h and 5h, the particle size increased a little and the crystallinity was improved. GAGs inhibited HAP crystal growth and stabilized HAP nanoparticles. Based on the TEM observation and size distribution determination of HAP nanoparticles, the possible formation mechanism of HAP nanoparticles stabilized by GAGs under UI was discussed. PMID:16904363

Han, Yingchao; Li, Shipu; Wang, Xinyu; Bauer, Ingo; Yin, Meizhen

2007-03-01

335

Gas sensing properties of ZnFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

Gas sensing performance of ZnFe2O4 ferrite nanoparticles towards various organic volatile compounds is investigated. A self-combustion of a citrate-gel precursor at ~90 °C in ambient air followed by annealing at 400 °C for 2 h has been explored to prepare a single phase spinel ferrite powder containing granular nanoparticles of average 23 nm diameters. A powder compact measures chemiresistive sensitivity of 59, 51, and 67% for organic vapor-analytes methanol, ethanol, and acetone respectively of 200 ppm at 250 °C. Excellent sensitivity of the granular nanoparticles results due to a large surface area to volume ratio effect.

Misra, Susmita; Ram, S.

2013-06-01

336

Particle size control of silver nanoparticles prepared by pulsed wire discharge in liquid media  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were prepared by pulsed wire discharge (PWD) using silver wire in deionized water at various relative energy (K) from 10 to 98, which is ratio of the charged energy of the capacitor in the electrical circuit to the vaporization energy of the wire. From energy deposition calculated by the measured voltage and current waveforms, deposited energy of the wire was increased with increasing K. From X-ray diffraction (XRD) analysis, prepared nanoparticles were phase identified as silver. From transmission electron microscopy observations, the shape of prepared silver nanoparticles were spherical and the median particle diameter (D50) and the geometric standard deviation (?g) were calculated from the particle distribution. D50 was decreased from 34 to 19 nm with increasing K. The particle size in prepared by PWD in liquid media can be controlled by K.

Tokoi, Y.; Josho, K.; Izuari, Y. M.; Suzuki, T.; Nakayama, T.; Suematsu, H.; Lee, S. W.; Fu, Z.; Niihara, K.

2011-03-01

337

Synthesis and characterization of CoFe 2O 4 magnetic nanoparticles prepared by temperature-controlled coprecipitation method  

Microsoft Academic Search

Magnetic nanoparticles of cobalt ferrite (CoFe2O4) have been synthesized in a homogeneous aqueous solution without any template and subsequent heat treatment. The average particle size could be varied in the range of 2–14nm by controlling coprecipitation temperature of Co2+ and Fe3+ ions in alkaline solution although the size distribution is pretty wide. As the precipitation temperature increased in the range

Yeong Il Kim; Don Kim; Choong Sub Lee

2003-01-01

338

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

PubMed

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. Avidin was attached to the surface of the thiolated nanoparticles via a bifunctional spacer which reacted in a first step with amino groups of avidin and in a second step with the sulfhydryl groups introduced onto the surface of the nanoparticles. Biotinylated peptide nucleic acid (PNA) as a model compound for biotinylated drugs was effectively coupled to the nanoparticles by complex formation with the covalently attached avidin. Since the formation of the interaction between biotin and avidin is very rapid and stable a highly effective drug carrier system for biotinylated compounds such as PNAs was achieved. PMID:10799823

Langer, K; Coester, C; Weber, C; von Briesen, H; Kreuter, J

2000-05-01

339

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

340

Sample preparation and EFTEM of Meat Samples for Nanoparticle Analysis in Food  

NASA Astrophysics Data System (ADS)

Nanoparticles are used in industry for personal care products and the preparation of food. In the latter application, their functions include the prevention of microbes' growth, increase of the foods nutritional value and sensory quality. EU regulations require a risk assessment of the nanoparticles used in foods and food contact materials before the products can reach the market. However, availability of validated analytical methodologies for detection and characterisation of the nanoparticles in food hampers appropriate risk assessment. As part of a research on the evaluation of the methods for screening and quantification of Ag nanoparticles in meat we have tested a new TEM sample preparation alternative to resin embedding and cryo-sectioning. Energy filtered TEM analysis was applied to evaluate thickness and the uniformity of thin meat layers acquired at increasing input of the sample demonstrating that the protocols used ensured good stability under the electron beam, reliable sample concentration and reproducibility.

Lari, L.; Dudkiewicz, A.

2014-06-01

341

Preparation of lisinopril-capped gold nanoparticles for molecular imaging of angiotensin-converting enzyme  

NASA Astrophysics Data System (ADS)

Overexpression of angiotensin-converting enzyme (ACE) has been associated with the pathophysiology of cardiac and pulmonary fibrosis. Moreover, the prescription of ACE inhibitors, such as lisinopril, has shown a favorable effect on patient outcome for patients with heart failure or systemic hypertension. Thus targeted imaging of the ACE would be of crucial importance for monitoring tissue ACE activity as well as the treatment efficacy in heart failure. In this respect, lisinopril-coated gold nanoparticles were prepared to provide a new type of probe for targeted molecular imaging of ACE by tuned K-edge computed tomography (CT) imaging. The preparation involved non-modified lisinopril, using its primary amine group as the anchoring function on the gold nanoparticles surface. The stable lisinopril-coated gold nanoparticles obtained were characterized by UV-vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM). Their zeta potential was also measured in order to assess the charge density on the modified gold nanoparticles (GNPs).

Li, Yuan; Baeta, Cesar; Aras, Omer; Daniel, Marie-Christine

2009-05-01

342

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.

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

2012-01-01

343

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

344

Preparation of monodisperse and size-controlled poly(ethylene glycol) hydrogel nanoparticles using liposome templates.  

PubMed

Liposomes were used as templates to prepare size-controlled and monodisperse poly(ethylene glycol) (PEG) hydrogel nanoparticles. The procedure for the preparation of PEG nanoparticles using liposomes consists of encapsulation of photopolymerizable PEG hydrogel solution into the cavity of the liposomes, extrusion through a membrane with a specific pore size, and photopolymerization of the contents inside the liposomes by UV irradiation. The size distributions of the prepared particles were 1.32+/-0.16 microm (12%), 450+/-62 nm (14%), and 94+/-12 nm (13%) after extrusion through membrane filters with pore sizes of 1 microm, 400 nm, and 100 nm, respectively. With this approach, it is also possible to modify the surface of the hydrogel nanoparticles with various functional groups in a one-step procedure. To functionalize the surface of a PEG nanoparticle, methoxy poly(ethylene glycol)-aldehyde was added as copolymer to the hydrogel-forming components and aldehyde-functionalized PEG nanoparticles could be obtained easily by UV-induced photopolymerization, following conjugation with poly-L-lysine-FITC through amine-aldehyde coupling. The prepared PEG particles showed strong fluorescence from FITC on the edge of the particles using confocal microscopy. The immobilization of biomaterials such as enzymes in hydrogel particles could be performed with loading beta-galactosidases during the hydration step for liposome preparation without additional procedures. The resorufin produced by applying resorufin beta-D-galactopyranoside as the substrate showed the fluorescence under the confocal microscopy. PMID:19081576

An, Se Yong; Bui, Minh-Phuong Ngoc; Nam, Yun Jung; Han, Kwi Nam; Li, Cheng Ai; Choo, Jaebum; Lee, Eun Kyu; Katoh, Shigeo; Kumada, Yoichi; Seong, Gi Hun

2009-03-01

345

Methoxypolyethylene Glycol Cyanoacrylate-Docosyl Cyanoacrylate Graft Copolymer: Synthesis, Characterization, and Preparation of Nanoparticles  

Microsoft Academic Search

Amphiphilic poly (MePEG-co-alkyl cyanoacrylate) copolymers have been studied as carriers for stealth nanoparticles. A promising area is nanoparticles prepared using copolymers with both high ratio of PEG blocks and sufficient hydrophobicity. In this study, poly (MePEG cyanoacrylate-co-docosyl cyanoacrylate) copolymer with longer alkyl chains has been synthesized by condensing MePEG cyanoacetate and docosyl cyanoacetate with formaldehyde in the presence of pyrrolidine.

Xiuli Wei; Hui Yan; Huinan Xu; Wei Wu

2006-01-01

346

Preparation of indium tin oxide (ITO) nanoparticles by DC arc plasma  

Microsoft Academic Search

Tin-doped indium oxide (ITO) nanoparticles were prepared by DC arc plasma. The mixture of In(OH)3 and SnCl2 as precursors was injected into the arc plasma through a powder feeder and vaporized by the arc plasma. The ITO nanoparticles were synthesized through the rapid quenching of the thermal plasma processing and did not require post-treatment. The doped level of the synthesized

Dong-Wook Kim; Dong-Wha Park

2010-01-01

347

Structural, optical and photoelectric properties of indium-doped zinc oxide nanoparticles prepared in dimethyl sulphoxide  

Microsoft Academic Search

ZnO and In3+-doped ZnO nanoparticles were prepared by homogeneous nucleation in a dimethyl sulphoxide (DMSO). During the synthesis the concentration of the zinc acetate precursor (0.01–0.1moldm?3) and the In3+\\/Zn2+ molar ratio (0.01–0.1) were varied. The crystalline structure of the nanoparticles was investigated by X-ray diffraction. The thermal behaviour of the particles was determined by thermogravimetric (TG) and differential scanning calorimetric

Imre Dékány

2008-01-01

348

Preparation of silver nanoparticles on cellulose nanocrystals and the application in electrochemical detection of DNA hybridization  

Microsoft Academic Search

Synthesis of Ag nanopaticles was carried out with carboxylated cellulose nanocrystals as the scaffolds by reducing metallic\\u000a cations using NaBH4. Ag particles with a size less than 10 nm were readily prepared and dispersed well. The carboxyl and hydroxyl groups of carboxylated\\u000a cellulose nanocrystals supplied a coordination effect to adsorb metallic cations and Ag nanoparticles, which prevent the aggregation\\u000a of nanoparticles.

He Liu; Dan Wang; Zhanqian Song; Shibin Shang

2011-01-01

349

In situ preparation of CaCO 3\\/polystyrene composite nanoparticles  

Microsoft Academic Search

CaCO3\\/polystyrene inorganic\\/organic composite nanoparticles (80 nm) with a core\\/shell structure were obtained by in situ emulsion polymerization of styrene (St) on the surface of modified CaCO3 nanoparticles. The nanometer CaCO3 slurry was prepared via carbonation of a Ca(OH)2 slurry in the presence of sodium oleate at room temperature in order to introduce polymerizable groups onto its surface. TEM photographs of composite

Ye Sheng; Jingzhe Zhao; Bing Zhou; Xuefeng Ding; Yanhui Deng; Zichen Wang

2006-01-01

350

Preparation and characterization novel polymer-coated magnetic nanoparticles as carriers for doxorubicin  

Microsoft Academic Search

The poly(lactide-co-glycolide)-coated magnetic nanoparticles (PLGA MNPs) were prepared as carriers of doxorubicin (PLGA–DOX MNPs) through water-in-oil-in-water (W\\/O\\/W) emulsification method. The characteristics of PLGA–DOX MNPs were measured by using transmission electron microscopy (TEM) and vibrating-sampling magnetometry (VSM). It was found that the synthesized nanoparticles were spherical in shape with an average size of 100±20nm, low aggregation and good magnetic responsivity. Meanwhile,

Fang Li; Jing Sun; Huaishi Zhu; Xuejun Wen; Chao Lin; Donglu Shi

2011-01-01

351

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

352

Preparation of novel magnetic fluorescent nanoparticles using amino acids.  

PubMed

Nanotechnology has opened new gates to pharmaceutical sciences and medicine from the aspect of drug delivery and imaging systems. Currently, bimodal fluorescent-magnetic nanoparticles are of great interest to biomedical scientists. In order to constructing these kinds of nanoparticles, fluorescent molecules should be linked to a magnetic core, while luminescence quenching is prevented. In order to alleviate this effect, usually fluorescent molecules are attached to a magnetic core after a multistep hydrocarbon, polymer or silica coating, which significantly increases the particle's size and reduces its magnetic saturation value. In this study, for the first time, amino acids (L-lysine and L-arginine) have been used as a linker and spacer between a fluorescent molecule (FITC) and a magnetic nanoparticle (Fe(3)O(4)) in a simple, two-step synthesis. Also, 3-aminopropyltriethoxysilane (APTES) was used without any previous silica coating for fluorescent magnetic nanoparticles construction. Routinely APTES is used after silica coating by tetraethoxysilane (TEOS). Either of L-lysine, L-arginine and APTES coating provides surface functional groups which interact with the isothiocyanate group of FITC. According to the obtained results, amino acids could be used for successful construction of fluorescent magnetic nanoparticles in a simple synthesis pathway, without any significant impact on the excitation and emission properties of fluorescent molecule. PMID:23104022

Ebrahiminezhad, Alireza; Ghasemi, Younes; Rasoul-Amini, Sara; Barar, Jaleh; Davaran, Soodabeh

2013-02-01

353

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

354

Colloidal formulations of etoposide based on poly(butyl cyanoacrylate) nanoparticles: preparation, physicochemical properties and cytotoxicity.  

PubMed

This article describes the preparation, physicochemical characterization and cytotoxicity assessment of novel colloidal formulations of etoposide based on poly(butyl cyanoacrylate) nanoparticles. Nanoparticles were prepared by controlled emulsion polymerization of butyl cyanoacrylate in aqueous medium using two different non-ionic colloidal stabilizers (pluronic F68 and polysorbate 80). The nanoparticles were spherical in shape, with average size ranging from 110-150 nm (empty nanoparticles) to 170-260 nm (drug-loaded nanoparticles), monomodal size distributions, and negative zeta-potentials at pH 7.4. Drug loading efficiency was around 63-68%. More than 80% of the drug was released from the formulations within 6-7h of dialysis experiments. Pluronic-coated nanoparticles possessed lower magnitude of the ?-potentials (around -4 mV) in comparison with the polysorbate-coated ones (around -12 mV). All tested etoposide formulations induced apoptosis in adenocarcinoma human epithelial (A549) cells, as evident from condensation of chromatin and fragmentation of nuclei. It was found that etoposide formulated with poly(butyl cyanoacrylate) nanoparticles and polysorbate 80 exhibited the highest cytotoxicity toward adenocarcinoma cells. PMID:23010022

Yordanov, Georgi; Skrobanska, Ralica; Evangelatov, Alexander

2013-01-01

355

Preparation of magnetic Fe3O4@SiO2 nanoparticles for immobilization of lipase.  

PubMed

Magnetic Fe3O4 nanoparticles were prepared with coprecipitatation method and covered with SiO2 to form the core-shell Fe3O4@SiO2 nanoparticles. Then the nanoparticles were modified with glutaradehyde for functionalization of the surface to aldehyde groups. The transmission electron microscopy confirmed the core-shell structure and revealed that the size of the nanoparticles was around 10 nm. It was observed that the lipase was immobilized on the nanoparticles successfully from the Fourier transform infrared spectra. The immobilized lipase on Fe3O4@SiO2 nanoparticles was characterized and compared to free enzyme. There are no significant differences observed in the optimal pH, temperature and Km before and after immobilization. However, the immobilized lipase displayed higher relative activity in the range of pH from 7.0 to 9.5. Compare with the free enzyme, the immobilized one showed higher thermal stability at temperature range from 30 to 70 degrees C, especially at high temperature. The relative activity of immobilized enzyme was 5.8 fold of the free lipase at 70 degrees C after 10 h incubation. Thus, the prepared lipase was proved to have the advantages like higher relative activity, better stability, broader pH range and easy to recovery. These results suggest that immobilization of lipase on Fe3O4@SiO2 nanoparticles has the potential industrial applications. PMID:24734736

Liu, Wei; Zhou, Fang; Zhang, Xiao-Yun; Li, Yue; Wang, Xiang-Yu; Xu, Xi-Ming; Zhang, Ye-Wang

2014-04-01

356

Preparation, physicochemical characterization and performance evaluation of gold nanoparticles in radiotherapy.  

PubMed

Purpose: The aim of the present study was preparation, physicochemical characterization and performance evaluation of gold nanoparticles (GNPs) in radiotherapy. Another objective was the investigation of anti-bacterial efficacy of gold nanoparticle against E. coli clinical strains. Methods: Gold nanoparticles prepared by controlled reduction of an aqueous HAuCl4 solution using Tri sodium citrate. Particle size analysis and Transmission electron microscopy were used for physicochemical characterization. Polymer gel dosimetry was used for evaluation of the enhancement of absorbed dose. Diffusion method in agar media was used for investigation of anti-bacterial effect. Results: Gold nanoparticles synthesized in size range from 57 nm to 346 nm by planning different formulation. Gold nanoparticle in 57 nm size increased radiation dose effectiveness with the magnitude of about 21 %. At the concentration of 400 ppm, Nano gold exhibited significant anti-bacterial effect against E. coli clinical strains. Conclusion: It is concluded that gold nanoparticles can be applied as dose enhancer in radiotherapy. The Investigation of anti-bacterial efficacy showed that gold nanoparticle had significant effect against E. coli clinical strains. PMID:24312871

Kamiar, Ali; Ghotalou, Reza; Vali Zadeh, Hadi

2013-01-01

357

Diverse Structural and Magnetic Properties of Differently Prepared MnAs Nanoparticles  

SciTech Connect

Discrete nanoparticles of MnAs with distinct magnetostructural properties have been prepared by small modifications of solution-phase arrested precipitation reactions. Rietveld and X-ray atomic pair distribution function based approaches were used to explore the evolution of the structure of the samples with temperature, and these data were compared to the magnetic response measured with ac susceptibility. Relative to a bulk standard, one type of MnAs nanoparticles was found to demonstrate similar but smaller structural transitions and corresponding magnetic changes. However, both magnetic and structural transitions in the second type of nanoparticles are strongly suppressed.

Billinge, S.J.; Tian, P.; Zhang, Y.; Senevirathne, K.; Brock, S.L.; Dixit, A.; Lawes, G.

2011-04-01

358

Preparation and characterization of methyltrimethoxysilane-Ag nanoparticles using chemical reduction at room temperature  

NASA Astrophysics Data System (ADS)

A new, direct, simple and high yield solution phase synthesis for preparing narrow-sized silver nanoparticles by chemical reduction in aqueous solution of AgNO3 in the presence of incorporated Sn particles in methyltrimethoxysilane (MTMS) at room temperature is reported. The resulting MTMS-silver nanoparticles were characterized by means of powder X-ray diffraction and transmission electron microscopy. The produced Ag particles present a tight size distribution with an average diameter of about 15 nm. Dispersed silver nanoparticles in tetrahydrofuran-dimethylformamide (1:1) mixture exhibit some broad surface plasmon resonance bands in UV-visible spectrum.

Farasat, Mahshid; Golzan, Mir Maqsood

2014-03-01

359

Method for the preparation of a composition of nanoparticles of at least one crystalline metal oxide  

US Patent & Trademark Office Database

The invention relates to a method for the preparation of a composition of nanoparticles of at least one crystalline metal oxide from at least one organometallic precursor. One precursor(s) which can react spontaneously to oxidation is selected; a liquid solution of the precursor(s) is produced in a solvent non-aqueous medium, and the liquid solution is placed in contact with at least one oxidant in adapted reactional conditions in order to directly result in the production of nanoparticles of crystalline metal oxide(s). The invention also relates to a composition of nanoparticles obtained in the form of a colloidal liquid solution.

2010-04-27

360

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.

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

361

Preparation of New Reducing Agent for the Synthesis of Silver Nanoparticles  

NASA Astrophysics Data System (ADS)

2,3,5,6-Tetrakis-(morpholinomethyl)hydroquinone (TMMH) is used first time to prepare spherical silver nanoparticles by the reduction of Silver nitrate (AgNO3) in water-ethanol medium without using any stabilizing and capping agent. The compound (TMMH) was isolated by aminomethylation of hydroquinone with morpholine. The resultant compound characterized by 1H NMR, 13C NMR and FT-IR Spectra for conformation studies. The ratio of AgNO3 and compound (TMMH) played role in controlling the particle size and shape of silver nanoparticles. The formation of the silver nanoparticles was observed in UV-Vis absorption spectroscopy.

Manivel, P.; Sivashanmugan, K.; Viswanathan, C.; Mangalaraj, D.

2011-07-01

362

Preparation of hollow titania nanoparticles of single-nanometer size using a PAMAM dendrimer template.  

PubMed

Hollow titania nanoparticles of single-nanometer size have been prepared from titanium oxysulfate (TiOSO?) using poly(amidoamine) (PAMAM) dendrimer molecules (Generations 5 with amino terminal groups) as a template. At low pH (pH 1), hydrolysis of the titania precursor was attenuated and the sol-gel reaction preferentially proceeded at the dendrimer surface. Calcination at 450°C yielded crystalline titania nanoparticles of 5.5 nm diameter with a ~2 nm cavity. These hollow titania nanoparticles showed a larger band-gap energy than solid particles of corresponding size. PMID:23985494

Sorida, Nao; Hakoda, Shuichiro; Torigoe, Kanjiro; Endo, Takeshi; Sakai, Kenichi; Sakai, Hideki; Abe, Masahiko

2013-01-01

363

Structural and magnetic properties of La3+ substituted strontium hexaferrite nanoparticles prepared by citrate precursor method  

NASA Astrophysics Data System (ADS)

Lanthanum (La3+) doped strontium ferrite is a promising material for high density perpendicular recording media due to high magnetocrystalline anisotropy and coercivity. The effects of La3+ on magnetic properties have been analyzed using vibrating sample magnetometer and discussed. The results show that the coercivity has been improved by substitution of La3+ on iron sites; coercivity value found to be increased with increase in La3+ content and is maximum for x=0.63 in SrLaxFe12-xO19, indicating the high magnetocrystalline anisotropy. La3+ doped strontium ferrite, prepared by citrate precursor technique, have been analyzed by means of X-ray diffraction (XRD), field emission scanning electron microscopy, fourier transform infrared spectroscopy and inductance capacitance resistance meter bridge. The XRD analysis shows that crystalline ferrite phase with hexagonal structure (P63/mmc) have been formed when the precursor calcined at 900 °C for 5 h. The crystallite size is found in the range of 31-38 nm and the elemental composition has been examined by energy dispersive X-ray. The dc electrical resistivity has been found to be increased with increasing La3+ content.

Thakur, Ankush; Singh, R. R.; Barman, P. B.

2013-01-01

364

Aqueous Solution Preparation, Structure, and Magnetic Properties of Nano-Granular ZnxFe3?xO4 Ferrite Films  

PubMed Central

This paper reports a simple and novel process for preparing nano-granular ZnxFe3?xO4 ferrite films (0 ? x ? 0.99) on Ag-coated glass substrates in DMAB-Fe(NO3)3-Zn(NO3)2 solutions. The deposition process may be applied in preparing other cations-doped spinel ferrite films. The Zn content x in the ZnxFe3?xO4 films depends linearly on the Zn2+ ion concentration ranging from 0.0 to 1.0 mM in the aqueous solutions. With x increasing from 0 to 0.99, the lattice constant increases from 0.8399 to 0.8464 nm; and the microstructure of the films changes from the non-uniform nano-granules to the fine and uniform nano-granules of 50–60 nm in size. The saturation magnetization of the films first increases from 75 emu/g to the maximum 108 emu/g with x increasing from 0 to 0.33 and then decreases monotonously to 5 emu/g with x increasing from 0.33 to 0.99. Meanwhile, the coercive force decreases monotonously from 116 to 13 Oe.

2010-01-01

365

Streptomycin-loaded PLGA-alginate nanoparticles: preparation, characterization, and assessment  

NASA Astrophysics Data System (ADS)

The aim of this study was to formulate and characterize streptomycin-loaded PLGA-alginate nanoparticles for their potential therapeutic use in Salmonella subsp. enterica ATCC 14028 infections. The streptomycin nanoparticle was prepared by solvent diffusion method, and the other properties such as size, zeta potential, loading efficacy, release kinetics, and antimicrobial strength were evaluated. The survey shows that nanoparticles may serve as a carrier of streptomycin and may provide localized antibacterial activity in the treatment of Salmonellosis. Electron microscopy showed spherical particles with indentations. The average size of the nanoparticles was 90 nm. At pH 7.2, the release kinetics of streptomycin from the nanoparticles was successfully illustrated as an initial burst defined by a first order equation that after this stage, it has a drastic tendency to obtain steady state. Nevertheless, nanoparticles showed loading efficacy nearly about 70-75 %. In addition, the tendency of concentration of streptomycin released from nanoparticles to reach antibacterial activity was similar to that of free streptomycin against PLGA-alginate, but it had threefold more antimicrobial strength in comparison with free streptomycin. This work shows the potential use of streptomycin-loaded PLGA-alginate nanoparticles and its capability.

Asadi, Asadollah

2013-04-01

366

Streptomycin-loaded PLGA-alginate nanoparticles: preparation, characterization, and assessment  

NASA Astrophysics Data System (ADS)

The aim of this study was to formulate and characterize streptomycin-loaded PLGA-alginate nanoparticles for their potential therapeutic use in Salmonella subsp. enterica ATCC 14028 infections. The streptomycin nanoparticle was prepared by solvent diffusion method, and the other properties such as size, zeta potential, loading efficacy, release kinetics, and antimicrobial strength were evaluated. The survey shows that nanoparticles may serve as a carrier of streptomycin and may provide localized antibacterial activity in the treatment of Salmonellosis. Electron microscopy showed spherical particles with indentations. The average size of the nanoparticles was 90 nm. At pH 7.2, the release kinetics of streptomycin from the nanoparticles was successfully illustrated as an initial burst defined by a first order equation that after this stage, it has a drastic tendency to obtain steady state. Nevertheless, nanoparticles showed loading efficacy nearly about 70-75 %. In addition, the tendency of concentration of streptomycin released from nanoparticles to reach antibacterial activity was similar to that of free streptomycin against PLGA-alginate, but it had threefold more antimicrobial strength in comparison with free streptomycin. This work shows the potential use of streptomycin-loaded PLGA-alginate nanoparticles and its capability.

Asadi, Asadollah

2014-04-01

367

Effect of PVP on the low temperature bonding process using polyol prepared Ag nanoparticle paste for electronic packaging application  

NASA Astrophysics Data System (ADS)

There has been an increasing interest in developing low temperature interconnection process using metal nanoparticles. In this study the Ag nanoparticles (NPs) for this low temperature bonding process applications were prepared based on the polyol method using polyvinylpyrrolidone (PVP) as the protecting agent. The effect of PVP on the Ag nanoparticle size, nanoparticle solution viscosity and the bondability of the Ag nanoparticle paste were studied. The silver nanoparticle with diameter of 90 nm, 40 nm and 20 nm were synthesized by adjusting PVP concentration. The bonding processes using different kind of Ag nanoparticle paste were conducted. The joint with shear strength of 50 MPa were formed using Ag nanoparticle (NP) paste prepared with appropriate PVP concentration.

Yan, Jianfeng; Zou, Guisheng; Wu, Aiping; Ren, Jialie; Yan, Jiuchun; Hu, Anming; Liu, Lei; Zhou, Y. Norman

2012-08-01

368

Gold Nanoparticles: Preparation, Properties, and Applications in Bionanotechnology  

PubMed Central

Gold nanoparticles (AuNPs) are important components for biomedical applications. AuNPs have been widely employed for diagnostics, and have seen increasing use in the area of therapeutics. In this mini-review, we present fabrication strategies for AuNPs and highlight a selection of recent applications of these materials in bionanotechnology.

Yeh, Yi-Cheun; Creran, Brian; Rotello, Vincent M.

2014-01-01

369

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

370

NMR-D study of the local spin dynamics and magnetic anisotropy in different nearly monodispersed ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

We present a systematic experimental comparison of the superparamagnetic relaxation time constants obtained by means of dynamic magnetic measurements and 1H-NMR relaxometry, on ferrite-based nanosystems with different composition, various core sizes and dispersed in different solvents. The application of a heuristic model for the relaxivity allowed a comparison between the reversal time of magnetization as seen by NMR and the results from the AC susceptibility experiments, and an estimation of fundamental microscopic properties. A good agreement between the NMR and AC results was found when fitting the AC data to a Vogel-Fulcher law. Key parameters obtained from the model have been exploited to evaluate the impact of the contribution from magnetic anisotropy to the relaxivity curves and estimate the minimum approach distance of the bulk solvent.

Bordonali, L.; Kalaivani, T.; Sabareesh, K. P. V.; Innocenti, C.; Fantechi, E.; Sangregorio, C.; Casula, M. F.; Lartigue, L.; Larionova, J.; Guari, Y.; Corti, M.; Arosio, P.; Lascialfari, A.

2013-02-01

371

Preparation and antibacterial activity of Fe3O4@Ag nanoparticles  

NASA Astrophysics Data System (ADS)

Bifunctional Fe3O4@Ag nanoparticles with both superparamagnetic and antibacterial properties were prepared by reducing silver nitrate on the surface of Fe3O4 nanoparticles using the water-in-oil microemulsion method. Formation of well-dispersed nanoparticles with sizes of 60 ± 20 nm was confirmed by transmission electron microscopy and dynamic light scattering. X-ray diffraction patterns and UV-visible spectroscopy indicated that both Fe3O4 and silver are present in the same particle. The superparamagnetism of Fe3O4@Ag nanoparticles was confirmed with a vibrating sample magnetometer. Their antibacterial activity was evaluated by means of minimum inhibitory concentration value, flow cytometry, and antibacterial rate assays. The results showed that Fe3O4@Ag nanoparticles presented good antibacterial performance against Escherichia coli (gram-negative bacteria), Staphylococcus epidermidis (gram-positive bacteria) and Bacillus subtilis (spore bacteria). Furthermore, Fe3O4@Ag nanoparticles can be easily removed from water by using a magnetic field to avoid contamination of surroundings. Reclaimed Fe3O4@Ag nanoparticles can still have antibacterial capability and can be reused.

Gong, Ping; Li, Huimin; He, Xiaoxiao; Wang, Kemin; Hu, Jianbing; Tan, Weihong; Zhang, Shouchun; Yang, Xiaohai

2007-07-01

372

Preparation and comparison of chitosan nanoparticles with different degrees of glutathione thiolation  

PubMed Central

Background Chitosan has gained considerable attentions as a biocompatible carrier to improve delivery of active agents. Application of this vehicle in the form of nanoparticle could profit advantages of nanotechnology to increase efficacy of active agents. The purpose of this study was to provide detailed information about chitosan–glutathione (Cht-GSH)nanoparticles which are gaining popularity because of their high mucoadhesive and extended drug release properties. Methods Depolymerization of chitosan was carried out using sodium nitrite method.Glutathione was covalently attached to chitosan and the solubility of the resulting conjugates was evaluated. Nanoparticles were prepared by ionic gelation method and then the effect of glutathione immobilization on properties of nanoparticles was investigated. Results Thiolation efficiency was higher in lower molecular weight chitosan polymers compared to unmodified chitosan nanoparticles. Cht-GSH conjugates of the same molecular weight but with different degrees of thiolation had the same hydrodynamic diameter (995± nm) and surface charge (102± mV) as unmodified chitosan, but comprised of a denser network structure and lower concentration. Cht-GSH nanoparticles also exhibited greater mucoadhesive strength which was less affected by ionic strength and pH of the environment. Conclusion Thiolation improves the solubility of chitosan without any significant changes in size and charge of nanoparticles, but affects the nanogel structure.

Yousefpour, P.; Atyabi, F.; Dinarvand, R.; Vasheghani-Farahani, E.

2011-01-01

373

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

374

Co-Pt nanoparticles encapsulated in carbon cages prepared by sonoelectrodeposition  

NASA Astrophysics Data System (ADS)

Co-Pt nanoparticles encapsulated in carbon cages have been prepared by sonoelectrodeposition followed by annealing in a CO atmosphere. Sonoelectrodeposition is a useful technique to make metallic nanoparticles, using ultrasound during electrodeposition to remove nanoparticles as they grow on the cathode surface. We used an electrolyte containing chloroplatinic acid and cobalt chloride and found that the atomic ratio of Co:Pt in the as-formed materials varied from 0.2 to 0.8 as the deposition current density was changed from 15 to 35 mA cm - 2. However, the as-deposited materials were inhomogeneous, comprising a mixture of Pt-rich and Co-rich nanoparticles. X-ray diffraction indicated that subsequent heat treatment (700 °C for 1 h) under CO gas created an ordered CoPt alloy phase that exhibited hard magnetic properties. Transmission electron microscopy showed many of the resulting nanoparticles to be encapsulated in carbon cages, which we ascribe to Co-catalyzed decomposition of CO during annealing. The thickness of the carbon cages was about ten layers, which may have helped reduce sintering during annealing. The size of the resultant nanoparticles was about 100 nm diameter, larger than the typical 5-10 nm diameter of as-deposited nanoparticles.

Hoang Luong, Nguyen; Hoang Hai, Nguyen; Dang Phu, Nguyen; MacLaren, D. A.

2011-07-01

375

Encapsulation of acetylshikonin by polyamidoamine dendrimers for preparing prominent nanoparticles.  

PubMed

Acetylshikonin (AS) has demonstrated antitumor potential. However, the development of therapeutic applications utilizing AS is inhibited by its poor solubility in water. In the present work, polyamidoamine (PAMAM) dendrimers and their PEGylated derivatives were employed to increase the solubility of AS. A distinct color transition was observed during the encapsulation of AS suggesting strong intermolecular forces between PAMAM and AS. Ultraviolet-visible, high-performance liquid chromatography, and (1)H NMR were used to verify the interaction between PAMAM and AS. The maximum amount of combined AS to each PAMAM molecule was determined. The cytotoxicity of AS nanoparticles was evaluated against leukemia (K562) and breast cancer (SK-BR-3) cell lines; the AS nanoparticles were shown to effectively inhibit tumor cells. PMID:24449188

Peng, Jianqing; Zhou, Wen; Xia, Xinyi; Qi, Xiaole; Sun, Luan; Wang, Min; Wu, Zhenghong; Li, Zhengrong

2014-04-01

376

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

377

Preparation and decoloration property of polystyrene-grafted palygorskite nanoparticles  

Microsoft Academic Search

The polymerization of styrene on inorganic palygorskite nanorods was carried out by reverse atom transfer radical polymerization (RATRP) in a completely controlled manner to form structurally well-defined PS-grafted hybrid nanocomposite. Well-defined PS chains were grown from the nanoparticle surfaces to yield individual particles composed of a palygorskite core and a well-defined outer PS layer. It has been found that the

Zi-Qiang Lei; Shou-Xin Wen

2007-01-01

378

Preparation of tourmaline nano-particles through a hydrothermal process and its infrared emission properties.  

PubMed

Tourmaline nano-particles were successfully prepared via a hydrothermal process using HCl as an additive. The reaction temperature (T) and the concentration of HCI (C(HCl)) had effects on the size and morphology of the tourmaline nano-particles. The optimum reaction condition was that: T = 180 degrees C and C(HCl) = 0.1 mol/l. The obtained nano-particles were spherical with the diameter of 48 nm. The far-infrared emissivity of the product was 0.923. The formation mechnism of the tourmaline nano-particles might come from the corrosion of grain boundary between the tourmaline crystals in acidic hydrothermal conditions and then the asymmetric contraction of the crystals. PMID:24734669

Xue, Gang; Han, Chao; Liang, Jinsheng; Wang, Saifei; Zhao, Chaoyue

2014-05-01

379

Preparation of silver nanoparticles in virgin coconut oil using laser ablation  

PubMed Central

Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10?8, 1.6 × 10?8, 2.4 × 10?8, respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method.

Zamiri, Reza; Azmi, B Z; Sadrolhosseini, Amir Reza; Ahangar, Hossein Abbastabar; Zaidan, A W; Mahdi, M A

2011-01-01

380

Preparation of anatase/rutile mixed-phase titania nanoparticles for dye-sensitized solar cells.  

PubMed

Acid-labile high surface mesoporous ZnO/Zn(OH)2 composite material is used as a novel hard template for the preparation of mesoporous amorphous TiO2. The template-free amorphous TiO2 material is then thermally crystallized at suitable temperature to control the relative ratio of anatase and rutile phases in a particle. Four different anatase/rutile (AR) mixed-phase TiO2 nanoparticles (AR-3, AR-15, AR-20, and AR-23 denoted for the samples of 3%, 15%, 20%, and 23% rutile phase, respectively) are prepared and characterized by powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). The coexistence of anatase and rutile phases in a TiO2 nanoparticle is visually confirmed by HRTEM analysis. These mixed-phase TiO2 nanoparticles are examined as candidates for photoelectrodes of dye-sensitized solar cells (DSSCs). The J-V curves and IPCE spectra for the DSSCs prepared from the mixed-phase TiO2 nanoparticles are obtained, and their photovoltaic properties are investigated. The photo-conversion efficiency (eta) indicates the highest value of 5.07% for AR-20. The synergistic effect of coexisting anatase and rutile phases with an optimal ratio in a TiO2 nanoparticle of AR-20 for an efficient interfacial transfer of photo-generated electrons is likely to lead to the highest efficiency among the AR-n samples. PMID:23755675

Hwang, Yong-Kyung; Park, Sung Soo; Lim, Jun-Heok; Won, Yong Sun; Huh, Seong

2013-03-01

381

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.

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

2013-01-01

382

Facile solvothermal preparation of monodisperse gold nanoparticles and their engineered assembly of ferritin-gold nanoclusters.  

PubMed

Herein, we report a quick and simple synthesis of water-soluble gold nanoparticles using a HAuCl4 and oleylamine mixture. Oleylamine serves as a reduction agent as well as a stabilizer for nanoparticle surfaces. The particle sizes can be adjusted by modulating reaction temperature and time. Solvothermal reduction of HAuCl4 with oleylamine can be confirmed by measuring the product in Fourier transform infrared (FTIR) spectroscopy. The plasmon band shifting from yellow to red confirms a nanosized particle formation. Amide bonds on the surface of the nanoparticles formed hydrogen bonds with one another, resulting in a hydrophobic monolayer. Particles dispersed well in nonpolar organic solvents, such as in hexane or toluene, by brief sonication. Next, we demonstrated the transfer of gold nanoparticles into water by lipid capsulation using 1-myristoyl-2-hydroxy-sn-glycero-3-phosphocholine (MHPC), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy polyethylene glycol)-2000 (DPPE-PEG2k), and 1,2-dioleoyl-sn-glycero-3-N-{5-amino-1-carboxypentyl}iminodiacetic acid succinyl nickel salt [DGS-NTA(Ni)]. The particle concentration can be obtained using an absorbance in ultraviolet-visible (UV-vis) spectra (at 420 nm). Instrumental analyses using transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) analysis, dynamic light scattering (DLS), and FTIR confirmed successful production of gold nanoparticles and fair solubility in water. Prepared gold particles were selectively clustered via engineered ferritin nanocages that provide multiple conjugation moieties. A total of 5-6 gold nanoparticles were clustered on a single ferritin nanocage confirmed in TEM. Reported solvothermal synthesis and preparation of gold nanoclusters may serve as an efficient, alternate way of preparing water-soluble gold nanoparticles, which can be used in a wide variety of biomedical applications. PMID:24283573

Choi, Jonghoon; Park, Sungwook; Stojanovi?, Zoran; Han, Hyung-Seop; Lee, Jongwook; Seok, Hyun Kwang; Uskokovi?, Dragan; Lee, Kwan Hyi

2013-12-17

383

Effective preparation of graphite nanoparticles using mechanochemical solid-state reactions  

NASA Astrophysics Data System (ADS)

The mechanochemical milling was utilized to control the nanostructures of plate-like graphite (Gp) microparticles in an argon atmosphere and at room temperature. The aggregated Gp nanoparticles were prepared by the simple solid-state process without organic solvent. Electron microscope observations, X-ray diffraction patterns and Raman spectra revealed the fractured plate-like Gp microparticles as well as the Gp microparticles agglomerated to each other through the dissociative edge surfaces by the milling process to finally generate the Gp nanoparticle aggregates. In the process, the ratio of the edge plane surfaces with the dangling bondings to layered internal surfaces clearly increased with the milling. Therefore, the low environmental burden process for preparing the Gp nanoparticle aggregation was achieved.

Motozuka, S.; Tagaya, M.; Ogawa, N.; Fukui, K.; Nishikawa, M.; Shiba, K.; Uehara, T.; Kobayashi, T.

2014-07-01

384

A novel method for the preparation of retinoic acid-loaded nanoparticles.  

PubMed

The goal of present work was to investigate the use of bioerodible polymeric nanoparticles as carriers of retinoic acid (RA), which is known to induce differentiation of several cell lines into neurons. A novel method, named "Colloidal-Coating", has been developed for the preparation of nanoparticles based on a copolymer of maleic anhydride and butyl vinyl ether (VAM41) loaded with RA. Nanoparticles with an average diameter size of 70 nm and good morphology were prepared. The activity of the encapsulated RA was evaluated on SK-N-SH human neuroblastoma cells, which are known to undergo inhibition of proliferation and neuronal differentiation upon treatment with RA. The activity of RA was not affected by the encapsulation and purification processes. PMID:19564952

Errico, Cesare; Gazzarri, Matteo; Chiellini, Federica

2009-05-01

385

Semiconductor nanoparticle-based hydrogels prepared via self-initiated polymerization under sunlight, even visible light  

PubMed Central

Since ancient times, people have used photosynthesized wood, bamboo, and cotton as building and clothing materials. The advantages of photo polymerization include the mild and easy process. However, the direct use of available sunlight for the preparation of materials is still a challenge due to its rather dilute intensity. Here, we show that semiconductor nanoparticles can be used for initiating monomer polymerization under sunlight and for cross-linking to form nanocomposite hydrogels with the aid of clay nanosheets. Hydrogels are an emerging multifunctional platform because they can be easily prepared using solar energy, retain semiconductor nanoparticle properties after immobilization, exhibit excellent mechanical strength (maximum compressive strength of 4.153?MPa and tensile strength 1.535?MPa) and high elasticity (maximum elongation of 2784%), and enable recyclable photodegradation of pollutants. This work suggests that functional nanoparticles can be immobilized in hydrogels for their collective application after combining their mechanical and physiochemical properties.

Zhang, Da; Yang, Jinhu; Bao, Song; Wu, Qingsheng; Wang, Qigang

2013-01-01

386

Structural and spectroscopic characterization of prepared Ag2S nanoparticles with a novel sulfuring agent.  

PubMed

Ag2S nanoparticles were prepared by a solvothermal process via reaction of Ag(NO3) and a new sulfuring agent from class of thio Schiff-base (2-(benzylidene amino) benzenethiol (C13H11NS)) in presence of various solvents. Spectra such as X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SEAD), ultraviolet-visible (UV-Vis) spectroscopy, thermo gravimetric-differential thermal analysis (TG-DTA), and Fourier transform Infrared (FT-IR) employed to characterize the synthesized products. Results of this paper indicate that shape and size of the silver sulfide can be controlled by means of setting certain reaction parameters such as the reaction temperature, presence of surfactant, and type of solvent. Silver sulfide nanoparticles with different morphology and size successfully prepared. In addition, the growth mechanisms of the Ag2S nanoparticles discussed preliminarily. PMID:24973787

Shakouri-Arani, Maryam; Salavati-Niasari, Masoud

2014-12-10

387

Green preparation and characterisation of waxy maize starch nanoparticles through enzymolysis and recrystallisation.  

PubMed

Waxy maize starch was treated by a facile and green enzymolysis procedure to fabricate starch nanoparticles (StNPs). The yield of StNPs was raised to 85% by pullulanase treatment, and the preparation duration was two days. Morphology (SEM, TEM), crystalline structure (XRD), thermal gravimetry analysis (TGA), and the group changing (FTIR) of StNPs prepared with different starch concentrations (10%, 15%, 20% and 25%,w/v) were investigated. Compared with native starch, the topography of all StNPs exhibited irregularly-shaped fragments, the particle diameters decreased from several ?m to about 60-120nm, and the crystal pattern changed from A-type to B+V-type. The StNPs prepared with 15% starch slurry had the highest degree of crystallinity at 55.41%. The eco-friendly prepared nanoparticles could be widely used in biomedical applications and development of new materials. PMID:24874379

Sun, Qingjie; Li, Guanghua; Dai, Lei; Ji, Na; Xiong, Liu

2014-11-01

388

Preparation of Highly Oil-Absorbing Resins Consisting of Hollow Nanoparticle Aggregates by Spray Drying  

Microsoft Academic Search

We report on the preparation of a novel poly(styrene-dodecyl methacrylate) (P(St-DMA)) absorbent resin by spray drying. The microstructures of the prepared resins have been examined by scanning electron microscope (SEM), showing that the resins consisted of hollow micrometer-sized spheres that were aggregated by nanoparticles. Meanwhile, the effects of the content of the cross-linker divinybenzene (DVB) on the oil absorption capacity,

Kaibing Huang; Xia Xiao; Zhenhua Chen; Jin Li

2009-01-01

389

Preparation of iron nanoparticles by reduction of acicular ?-FeOOH particles  

Microsoft Academic Search

Acicular ?-FeOOH nanoparticles were prepared either by oxidation of ferrous chloride in a lamellar liquid crystal phase at 60°C, or by forced hydrolysis of ferric chloride at 80°C. The particles prepared in the liquid crystal phase were rod-shaped, with an average length of 85 nm and an aspect ratio of 12. Sodium borohydride reduction of these particles gave needle-shaped iron

Min Chen; Bo Tang; David E. Nikles

1998-01-01

390

Preparation of Spherical and Triangular Silver Nanoparticles by a Convenient Method  

Microsoft Academic Search

Silver nanoparticles with spherical and triangular shapes were prepared in a convenient way (simple and rapid) at room temperature by chemical reduction method. The obtained Ag NPs were characterized by transmission electron microscopy and UV-visible spectrophotometer. The results indicated that, as silver nitrate, polyvinyl pyrrolidone and sodium borohydride were used as reagent, protective agent and reducing agent respectively, spherical and

Kai Li; Xiaotong Jia; Aiwei Tang; Xibin Zhu; Huan Meng; Yingfeng Wang

2012-01-01

391

Three dimensional film electrode prepared from oppositely charged carbon nanoparticles as efficient enzyme host  

Microsoft Academic Search

Three dimensional carbon film electrodes were prepared from oppositely charged carbon nanoparticles (ca. 9 to 18nm diameter) by a layer-by-layer approach. This was done by alternative immersion of indium tin oxide plates into suspension of positively and negatively charged particles. A stable film is formed already after single immersion and withdrawal step as confirmed by scanning electron microscopy. Up to

Katarzyna Szot; John D. Watkins; Steven D. Bull; Frank Marken; Marcin Opallo

2010-01-01

392

Iron oxide nanoparticles supported on ultradispersed diamond powders: Effect of the preparation procedure  

Microsoft Academic Search

The state of the iron oxide nanoparticles, supported on ultradispersed diamond (UDD) powders is studied by X-ray diffraction, nitrogen physisorption, temperature-programmed reduction, FTIR and Mössbauer spectroscopy. Methanol decomposition to hydrogen and CO is used as a catalytic test. The peculiarities of the iron oxide species strongly depend on the detonation procedure used for the UDD powders preparation as well as

Momtchil Dimitrov; Ljubomira Ivanova; Daniela Paneva; Tanya Tsoncheva; Stavry Stavrev; Ivan Mitov; Christo Minchev

2009-01-01

393

Preparation of Y2O3:Er,Yb nanoparticles by laser ablation in liquid  

NASA Astrophysics Data System (ADS)

We prepared a Y2O3:Er,Yb nanoparticles by laser ablation in liquid. The laser used the second harmonic generation Nd:YAG (532 nm). A preparation process and measurement of upconversion properties were performed by varying the range of the energy density of the laser. Images from scanning electron microscopy (SEM) indicated that two types of nanoparticles existed in the product of laser ablation in liquid. We concluded the following: one type of nanoparticles was prepared from the nucleation of materials in a plume and the other was prepared by fragmentation. In the photoluminescence spectra, green (2H11/2, 4S3/2 ? 4I15/2) and red (4F9/2 ? 4I15/2) fluorescence were observed using a 980 nm laser diode (LD) as the excitation source. We confirmed that the fluorescence intensity increased with increasing energy density of the laser. Thus, we concluded that the number of the nanoparticles increased as the energy density of the laser was increased.

Nunokawa, Takashi; Onodera, Yuji; Hara, Masahiko; Kitamoto, Yoshitaka; Odawara, Osamu; Wada, Hiroyuki

2012-11-01

394

Transmetallation as an effective strategy for the preparation of bimetallic CoPd and CuPd nanoparticles  

NASA Astrophysics Data System (ADS)

The preparation of palladium alloy nanoparticles is of great interest for many applications, especially in catalysis. Starting from presynthesized nanoparticles of a less noble metal, a transmetallation reaction involving a redox process at the nanoparticle surface can be exploited to modify the nanoparticle composition and crystalline phase. As an example, monodispersed ?-cobalt and face-centered cubic copper nanoparticles were synthesized in organic solvents at high temperature and the as-formed nanoparticles were reacted with palladium(ii) hexafluoroacetylacetonate resulting in the formation of alloyed nanoparticles whose composition closely follows the reactant ratio. The oxidative state of the nanoparticle surface greatly affects the success of the transmetallation reaction and a reduction treatment was necessary to achieve the desired final product. Electron microscopy and X-ray diffraction showed that for cobalt a limiting palladium content for the ?-phase alloy is found, above which an fcc alloy nucleates, while for copper the fcc crystalline phase is preserved throughout the whole composition range.

Bersani, Marco; Conte, Luca; Martucci, Alessandro; Guglielmi, Massimo; Mattei, Giovanni; Bello, Valentina; Rosei, Renzo; Centazzo, Massimo

2014-01-01

395

Characterization of ferrogels prepared using ?-Fe2O3 and Fe3O4 nanoparticles  

NASA Astrophysics Data System (ADS)

In this study, we compare the characteristics of ferrogels prepared using ?-Fe2O3 and Fe3O4 nanoparticles. The magnetic nanoparticles with ~ 20 nm diameter were distributed in N-isopropylacrylamide (NIPAM) gel prepared using N,N'-methylenebisacrylamide (BIS), ammonium persulfate (APS) and N,N,N',N'-tetramethylethylenediamine (TEMED). Particle distribution and agglomeration characteristics of the prepared ferrogels were investigated using ultra small angle x-ray scattering (USAXS) and transmission electron microscopy (TEM). The ferrogel samples prepared using Fe3O4 and ?-Fe2O3 particles have similar particle distribution. The ferrogels, prepared with ?-Fe2O3 nanoparticles, however, demonstrate significantly different agglomeration characteristics compared to the ferrogels prepared using Fe3O4. In both systems, the agglomerated particles appear to be spherical, with few of those indicating chain like structures. Based on the particle concentration and sizes, the DC SQUID magnetometry data of these samples showed the magnetic moments range between 0.9 to 2.5 emu/g. Details of our results and analysis are presented.

Suthar, Kamlesh J.; Ghantasala, Muralidhar K.; Mancini, Derrick C.; Ilavsky, Jan

2009-03-01

396

Structural, magnetic and electrical characterization of Mg-Ni nano-crystalline ferrites prepared through egg-white precursor  

NASA Astrophysics Data System (ADS)

Soft Ni-Mg nano-crystalline ferrites with the general formula Ni1-xMgxFe2O4 (0?x?1) were synthesized through egg-white method. The precursor decomposition was followed by thermal analysis techniques. The obtained ferrites were characterized by X-ray diffraction, Fourier transform infrared and transmission electron microscopy measurements. X-ray diffraction showed the cubic spinel structure with crystallite size variation within the range 20-45 nm. The different structural data obtained were discussed in the view of ionic radii of the entire ions and their distribution within the lattice. The appropriate suggested cation distribution was then confirmed through Fourier transform infrared as well as electrical and magnetic properties measurements. Transmission electron microscopy exhibited a nano-crystal aggregation phenomenon. The observed size of the spherical particles agrees well with that obtained by X-ray diffraction. Hysteresis loop measurements revealed dilution in the obtained magnetic parameters by Mg-substitution due to the preferential occupancy of Mg2+ ions by the octahedral sites. Ac-electrical conductivity as a function of temperature and frequency exhibited a semi-conducting behavior with conductivity decreases by increasing Mg-content. The change in the slope of the curve indicates the changing in the conduction mechanism from electron hopping to polaron mechanism by increasing temperature. The obtained structural, electrical and magnetic properties were explained based on the cation distribution among tetrahedral and octahedral sites.

Gabal, M. A.; Al Angari, Y. M.; Zaki, H. M.

2014-08-01

397

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

398

Microbial preparation of metal-substituted magnetite nanoparticles  

SciTech Connect

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 (MyFe3-yO4) from a doped precursor, mixed-M iron oxyhydroxide, (MxFe1-xOOH, x 0.5, M is Mn, Zn, Ni, Co, and Cr). Within the range of 0.01 x 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.

Moon, Ji Won [ORNL; Roh, Yul [Chonnam National University, Gwangju; Lauf, Robert J [ORNL; Vali, Hojatollah [McGill University, Montreal, Quebec; Yeary, Lucas W [ORNL; Phelps, Tommy Joe [ORNL

2007-01-01

399

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

400

Enhanced Oral Delivery of Docetaxel Using Thiolated Chitosan Nanoparticles: Preparation, In Vitro and In Vivo Studies  

PubMed Central

The aim of this study was to evaluate a nanoparticulate system with mucoadhesion properties composed of a core of polymethyl methacrylate surrounded by a shell of thiolated chitosan (Ch-GSH-pMMA) for enhancing oral bioavailability of docetaxel (DTX), an anticancer drug. DTX-loaded nanoparticles were prepared by emulsion polymerization method using cerium ammonium nitrate as an initiator. Physicochemical properties of the nanoparticles such as particle size, size distribution, morphology, drug loading, and entrapment efficiency were characterized. The pharmacokinetic study was carried out in vivo using wistar rats. The half-life of DTX-loaded NPs was about 9 times longer than oral DTX used as positive control. The oral bioavailability of DTX was increased to 68.9% for DTX-loaded nanoparticles compared to 6.5% for positive control. The nanoparticles showed stronger effect on the reduction of the transepithelial electrical resistance (TEER) of Caco-2 cell monolayer by opening the tight junctions. According to apparent permeability coefficient (Papp) results, the DTX-loaded NPs showed more specific permeation across the Caco-2 cell monolayer in comparison to the DTX. In conclusion, the nanoparticles prepared in this study showed promising results for the development of an oral drug delivery system for anticancer drugs.

Saremi, Shahrooz; Kebriaeezadeh, Abbas; Ostad, Seyed Nasser; Atyabi, Fatemeh

2013-01-01

401

A convenient method to prepare emulsified polyacrylate nanoparticles from powders [corrected] for drug delivery applications.  

PubMed

We describe a method to obtain purified, polyacrylate nanoparticles in a homogeneous powdered form that can be readily reconstituted in aqueous media for in vivo applications. Polyacrylate-based nanoparticles can be easily prepared by emulsion polymerization using a 7:3 mixture of butyl acrylate and styrene in water containing sodium dodecyl sulfate as a surfactant and potassium persulfate as a water-soluble radical initiator. The resulting emulsions contain nanoparticles measuring 40-50 nm in diameter with uniform morphology, and can be purified by centrifugation and dialysis to remove larger coagulants as well as residual surfactant and monomers associated with toxicity. These purified emulsions can be lyophilized in the presence of maltose (a non-toxic cryoprotectant) to provide a homogeneous dried powder, which can be reconstituted as an emulsion by addition of an aqueous diluent. Dynamic light scattering and microbiological experiments were carried out on the reconstituted nanoparticles. This procedure allows for ready preparation of nanoparticle emulsions for drug delivery applications. PMID:21704525

Garay-Jimenez, Julio C; Turos, Edward

2011-08-01

402

Chemical Preparation and Characterization of Elemental Cu, Ni, and Cu/Ni Core/Shell Nanoparticles  

NASA Astrophysics Data System (ADS)

Elemental Ni, Cu, and Cu core/Ni shell nanoparticles have been prepared in a polyol-type process. The elemental nanoparticles were prepared by dissolving NiCl2.6H2O and/or CuCl2.2H2O in ethylene glycol (EG) and heating the solution to reflux prior to the addition of NaOH. The resulting precipitate was then extracted, dried, and characterized by scanning electron microscopy (SEM) with elemental analysis, x-ray diffraction (XRD), and in the case of the elemental Ni nanoparticles, vibrating sample magnetometry (VSM) measurements. The best fit lattice parameters obtained from the elemental Ni and Cu nanoparticles were 0.35289(28) and 0.36171(23) nm, respectively, in good agreement with the corresponding bulk values. On the other hand, the measured saturation magnetization of about 49 emu/g was somewhat smaller than the bulk Ni value. In the case of the Cu/Ni nanoparticles, the best fit lattice parameters for the Ni and Cu components of the core/shell structure were 0.35299(26) and 0.36101(10) nm, indicating the formation of an essentially pure Ni shell and a slight amount of Ni incorporation in the Cu core.

Higgins, Laura; Lattanzi, Michael; Kelly, Brian; Poirier, Gerald; Unruh, Karl

2011-03-01

403

Preparation and characterization of galactosylated bovine serum albumin nanoparticles for liver-targeted delivery of oridonin.  

PubMed

In this study, galactosylated bovine serum albumin (GB), which could be developed for a liver targeting carrier was synthetized and it was identified by Fourier transform infrared (FT-IR) spectrometer. Oridonin loaded bovine serum albumin nanoparticle (ORI-BSA-NP) and oridonin loaded GB nanoparticle (ORI-GB-NP) were prepared and optimized by the desolvation technique. During the preparation of ORI-GB-NP, galactosamine was introduced to end-cap the free aldehyde groups on nanoparticles. The characteristics of ORI-GB-NP such as particle size, zeta potential, particle morphologie, entrapment efficiency and drug loading were evaluated. The nearly spherical nanoparticles, with a narrow size distribution below 200 nm, were negatively charged with zeta potential of about -30 mV. Meanwhile, differential scanning calorimetry (DSC) and X-ray diffraction confirmed the amorphous state of ORI in ORI-GB-NP. The in vitro drug release of ORI from ORI-GB-NP presented a biphasic pattern with an initial burst effect and consequently sustained release. These results implied that the nanoparticles possessed fine physicochemical characteristics and seemed to be a stable delivery system for poorly soluble oridonin. PMID:23518367

Li, Caiyun; Zhang, Dianrui; Guo, Hejian; Hao, Leilei; Zheng, Dandan; Liu, Guangpu; Shen, Jingyi; Tian, Xiaona; Zhang, Qiang

2013-05-01

404

Preparation and in vitro-in vivo evaluation of salmon calcitonin-loaded polymeric nanoparticles.  

PubMed

The aim of the study was to develop and characterize polymeric nanoparticles as a sustained release system for salmon calcitonin (sCT). Nanoparticles were prepared by a double emulsion solvent evaporation method using Eudragit RS and two types of a biodegradable poly(lactic-co-glycolic) copolymer (PLGA). It was demonstrated that sCT was incorporated into nanoparticles with encapsulation efficiencies in the range 69-83%. In vitro release studies, unconventionally conducted in 5% acetic acid, showed great differences in sCT release time profiles. Nanoparticles with fast release profile (Eudragit RS, PLGA/Eudragit RS) released 80-100% of the encapsulated drug within a few hours. In contrast, the sCT release from pure PLGA nanoparticles was very slow, incomplete and reached only 20% after 4 weeks. In vivo study, conducted in Wistar rats, proved that elevated serum sCT levels could be sustained for 3 days after subcutaneous administration of PLGA nanoparticles and the achieved bioavailability was increased compared to sCT solution. PMID:19229671

Glowka, Eliza; Sapin-Minet, Anne; Leroy, Pierre; Lulek, Janina; Maincent, Philippe

2010-01-01

405

Preparation, characterization and in vitro drug release studies of novel polymeric nanoparticles.  

PubMed

Polymeric nanoparticles of AADG cross-linked with MBA encapsulating water soluble macromolecules such as FITC-Dextran have been prepared in the reverse micellar system. The particles obtained were of >85nm in diameter which were highly monodisperse. An optically clear solution was obtained on redispersing these nanoparticles in aqueous buffer. Size and morphology of the particles remains the same on re-dispersing the lyophilized powder of these nanoparticles in aqueous buffer. The size dependency of the particles on the monomer and surfactant concentration was observed. The average size of the nanoparticles as obtained from DLS studies ranges from 74 to 114nm in case 0.06M AOT and 62-104nm in case of 0.1M AOT concentration. FITC-Dextran was entrapped into nanoparticles with high efficiency (>70%). The pH dependent release of the entrapped molecules from these nanoparticles was also studied. At pH 5.0 solution, approximately 43% of FITC-Dx was released and at pH 7.4 it was about 70%. PMID:16920286

Nimesh, Surendra; Manchanda, Romila; Kumar, Rupesh; Saxena, Amit; Chaudhary, Preeti; Yadav, Veena; Mozumdar, Subho; Chandra, Ramesh

2006-10-12

406

Preparation of porous polymer monoliths featuring enhanced surface coverage with gold nanoparticles  

PubMed Central

A new approach to the preparation of porous polymer monoliths with enhanced coverage of pore surface with gold nanoparticles has been developed. First, a generic poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith was reacted with cystamine followed by the cleavage of its disulfide bonds with tris(2-carboxylethyl)phosphine which liberated the desired thiol groups. Dispersions of gold nanoparticles with sizes varying from 5 to 40 nm were then pumped through the functionalized monoliths. The materials were then analyzed using both energy dispersive X-ray spectroscopy and thermogravimetric analysis. We found that the quantity of attached gold was dependent on the size of nanoparticles, with the maximum attachment of more than 60 wt% being achieved with 40 nm nanoparticles. Scanning electron micrographs of the cross sections of all the monoliths revealed the formation of a non-aggregated, homogenous monolayer of nanoparticles. The surface of the bound gold was functionalized with 1-octanethiol and 1-octadecanethiol, and these monolithic columns were used successfully for the separations of proteins in reversed phase mode. The best separations were obtained using monoliths modified with 15, 20, and 30 nm nanoparticles since these sizes produced the most dense coverage of pore surface with gold.

Lv, Yongqin; Alejandro, Fernando Maya; Frechet, Jean M. J.

2012-01-01

407

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.

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

2014-01-01

408

Nanostructures of functionalized gold nanoparticles prepared by particle lithography with organosilanes.  

PubMed

Periodic arrays of organosilane nanostructures were prepared with particle lithography to define sites for selective adsorption of functionalized gold nanoparticles. Essentially, the approach for nanoparticle lithography consists of procedures with two masks. First, latex mesospheres were used as a surface mask for deposition of an organosilane vapor, to produce an array of holes within a covalently bonded, organic thin film. The latex particles were readily removed with solvent rinses to expose discrete patterns of nanosized holes of uncovered substrate. The nanostructured film of organosilanes was then used as a surface mask for a second patterning step, with immersion in a solution of functionalized nanoparticles. Patterned substrates were fully submerged in a solution of surface-active gold nanoparticles coated with 3-mercaptopropyltrimethoxysilane. Regularly shaped, nanoscopic areas of bare substrate produced by removal of the latex mask provided sites to bind silanol-terminated gold nanoparticles, and the methyl-terminated areas of the organosilane film served as an effective resist, preventing nonspecific adsorption on masked areas. Characterizations with atomic force microscopy demonstrate the steps for lithography with organosilanes and functionalized nanoparticles. Patterning was accomplished for both silicon and glass substrates, to generate nanostructures with periodicities of 200-300 nm that match the diameters of the latex mesospheres of the surface masks. Nanoparticles were shown to bind selectively to uncovered, exposed areas of the substrate and did not attach to the methyl-terminal groups of the organosilane mask. Billions of well-defined nanostructures of nanoparticles can be generated using this high-throughput approach of particle lithography, with exquisite control of surface density and periodicity at the nanoscale. PMID:21928785

Lusker, Kathie L; Li, Jie-Ren; Garno, Jayne C

2011-11-01

409

Preparation and properties of amorphous titania-coated zinc oxide nanoparticles  

SciTech Connect

Amorphous TiO{sub 2}-coated ZnO nanoparticles were prepared by the solvothermal synthesis of ZnO nanoparticles in ethanol and the followed by sol-gel coating of TiO{sub 2} nanolayer. The analyses of X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that the resultant ZnO nanoparticles were hexagonal with a wurtzite structure and a mean diameter of about 60 nm. Also, after TiO{sub 2} coating, the TEM images clearly indicated the darker ZnO nanoparticles being surrounded by the lighter amorphous TiO{sub 2} layers. The zeta potential analysis revealed the pH dependence of zeta potentials for ZnO nanoparticles shifted completely to that for TiO{sub 2} nanoparticles after TiO{sub 2} coating, confirming the formation of core-shell structure and suggesting the coating of TiO{sub 2} was achieved via the adhesion of the hydrolyzed species Ti-O{sup -} to the positively charged surface of ZnO nanoparticles. Furthermore, the analyses of Fourier transform infrared (FTIR) and Raman spectra were also conducted to confirm that amorphous TiO{sub 2} were indeed coated on the surface of ZnO nanoparticles. In addition, the analyses of ultraviolet-visible (UV-VIS) and photoluminescence (PL) spectra revealed that the absorbance of amorphous TiO{sub 2}-coated ZnO nanoparticles at 375 nm gradually decreased with an increase in the Ti/Zn molar ratio and the time for TiO{sub 2} coating, and the emission intensity of ZnO cores could be significantly enhanced by the amorphous TiO{sub 2} shell. - Graphical abstract: Amorphous titania-coated ZnO nanoparticles with a core-shell structure were prepared. It was found that the emission intensity of ZnO cores could be significantly enhanced by the amorphous TiO{sub 2} shell.

Liao Minhung [Applied Science and Technology Research Center, Department of Cosmetology and Styling, Transworld Institute of Technology, Douliu 640, Yulin, Taiwan (China)]. E-mail: liaomh@mail.tit.edu.tw; Hsu, C.-H. [Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan 701 (China); Chen, D.-H. [Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan 701 (China)]. E-mail: chendh@mail.ncku.edu.tw

2006-07-15

410

Water-repellent coatings prepared by modification of ZnO nanoparticles  

NASA Astrophysics Data System (ADS)

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 ˜14 nm 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 Zn2+ 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.

Chakradhar, R. P. S.; Dinesh Kumar, V.

411

Preparation of linoleic acid-capped silver nanoparticles and their antimicrobial effect.  

PubMed

Silver nanoparticles have been prepared through the chemical reduction of silver ions by ethanol using linoleic acid as a stabilising agent. This colloidal solution shows an absorption band in the visible range with an absorption peak at 421 nm. The peaks in the X-ray diffraction (XRD) pattern matches well with the standard values of the face-centred-cubic form of metallic silver. Transmission Electron Microscope (TEM) micrograph shows a nearly uniform distribution of the particles with an average size of 8 nm. This linoleic acid-capped silver nanoparticles show antimicrobial activity against Escherichia coli and Staphylococcus aureus. PMID:22559712

Das, R; Gang, S; Nath, S S; Bhattacharjee, R

2012-06-01

412

[Preparation and antibacterial capacity of artificial skin loaded with nanoparticles silver using bacterial cellulose].  

PubMed

In the present paper, in-situ preparation of silver nanoparticles have been conducted in 3D network structure of BC membrane through liquid phase chemical deoxidization method. The characterization of products was investigated using scanning electron microscopy (SEM), infrared spectroscopy (IR), energy dispersion spectrometry (SEM-EDS). The absorbing water capacity and preserving water capacity of substitutes and the antibacterial capacities of antibacterial agent-loaded artificial skin were tested. The results showed the silver nanoparticles were approximately spherical particles with an average diameter of 45nm, and were noted to have excellent sterilizing efficacy the efficiency of against Escherichia coli, yeast and Candida albicans. PMID:19947484

Sun, Dongping; Yang, Jiazhi; Li, Jun; Zhou, Lingli; Yu, Junwei

2009-10-01

413

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

414

Structural and optical properties of ZnO nanoparticles prepared by chemical precipitation technique  

NASA Astrophysics Data System (ADS)

In this investigation, ZnO nanoparticles were prepared by chemical precipitation method. Ethylenediaminetetra acetic acid (EDTA) was used as a capping agent. The particles were characterized by XRD, UV-Vis spectroscopy, Scanning electron microscopy (SEM), and FTIR spectroscopy. Calculation based on the XRD data reveals that the synthesized ZnO nanoparticles are of hexagonal phase with ~ 40 nm average particle size. The surface morphology was investigated by using SEM and the elemental analysis by Energy dispersive analysis of X-rays (EDAX). Band gap was also calculated using UV-Vis spectroscopy. A standard peak of zinc oxide was observed at 480 cm-1 from FTIR spectroscopy.

Saini, Dinesh; Duchaniya, Rajendra Kumar; Kachhwaha, Sumita

2013-06-01

415

Size selected synthesis of CoFe2O4 nanoparticles prepared in a chitosan matrix  

NASA Astrophysics Data System (ADS)

In this paper we report the synthesis and magnetic properties of CoFe2O4 nanoparticles. The nanoparticles with sizes ranging from 6 to 20 nm were prepared in a chitosan matrix. Size selection was achieved by introducing a nonionic surfactant Tween-X, where X={20, 60, 80, and 85}. Aqueous dispersions of Tween-X show micelles with increasing hydrodynamic sizes as X increases. Mössbauer spectroscopy measurements at 300 K show superparamagnetic behavior for the small particles, changing gradually to a blocked magnetic regime as the particle size increases. Magnetization measurements at 300 K show increasing values for the ratio Mr/MHmax and coercive fields (Hc).

Gurgel, A. L.; Soares, J. M.; Chaves, D. S.; Chaves, D. S.; Xavier, M. M.; Morales, M. A.; Baggio-Saitovitch, E. M.

2010-05-01

416

SOFT MAGNETIC PROPERTIES OF Mg0.7-xNi0.3ZnxFe2O4 FERRITES SYNTHESIZED BY SOL-GEL AUTO-COMBUSTION TECHNIQUE WITHOUT POST-PREPARATION THERMAL TREATMENT  

NASA Astrophysics Data System (ADS)

Single phase nanocrystalline soft magnetic Mg0.7-xNi0.3ZnxFe2O4, ferrites with x = 0.0 - 0.7 were prepared by sol gel auto-combustion method. X-ray diffraction confirms the formation of single phase nano-crystalline cubic spinel ferrites with average grain diameter ranging between 12.9 nm to 23.9 nm. Formation of the ferrite phase without subsequent heat treatment makes sol-gel auto combustion technique especially suitable and economical for the large scale industrial production of the nano-crystalline ferrites for multilayer chip inductor applications (MLCI). Both, lattice parameter and X-ray density shows a linear increase with increasing Zn2+ concentration, attributed to the difference in ionic radii and density of Mg and Zn. Increase in Zn content enhances the soft magnetic behavior, exhibiting linear decrease of coercivity from 122.34 Oe to 72.45 Oe, explained by increase of density with Zn addition. The maximum magnetization (Mmax)increases up to 0.106 Tesla (for x = 0.4) and. then decreases with increase of Zn content, discussed on the basis of increase of the occupancy of A-site in spinel ferrite by non-magnetic Zn2+ ion.

Ghosh, A.; Satalkar, M.; Rathod, S.; Nag, S. P.; Vyas, P.; Kane, N.; Ghodke, N.; Prasad, R.; Dwivedi, R.

417

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

418

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

419

Synthesis and magnetic properties of the size-controlled Mn–Zn ferrite nanoparticles by oxidation method  

Microsoft Academic Search

Size-controlled Mn0.67Zn0.33Fe2O4 nanoparticles in the wide range from 80 to 20nm have been synthesized, for the first time, using the oxidation method. It has been demonstrated that the particle size can be tailor-made by varying the concentration of the oxidant. The magnetization of the 80nm particles was 49Am2kg?1 compared to 34Am2kg?1 for the 20nm particles. The Curie temperatures for all

R. Justin Joseyphus; A. Narayanasamy; K. Shinoda; B. Jeyadevan; K. Tohji

2006-01-01

420

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 wit