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Sample records for ultrasmall cofe2o4 nanoparticles

  1. Monodisperse polyvinylpyrrolidone-coated CoFe2O4 nanoparticles: Synthesis, characterization and cytotoxicity study

    NASA Astrophysics Data System (ADS)

    Wang, Guangshuo; Ma, Yingying; Mu, Jingbo; Zhang, Zhixiao; Zhang, Xiaoliang; Zhang, Lina; Che, Hongwei; Bai, Yongmei; Hou, Junxian; Xie, Hailong

    2016-03-01

    In this study, monodisperse cobalt ferrite (CoFe2O4) nanoparticles were prepared successfully with various additions of polyvinylpyrrolidone (PVP) by sonochemical method, in which PVP served as a stabilizer and dispersant. The effects and roles of PVP on the morphology, microstructure and magnetic properties of the obtained CoFe2O4 were investigated in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and superconducting quantum interference device (SQUID). It was found that PVP-coated CoFe2O4 showed relatively well dispersion with narrow size distribution. The field-dependent magnetization curves indicated superparamagnetic behavior of PVP-coated CoFe2O4 with moderate saturation magnetization and hydrophilic character at room temperature. More importantly, the in vitro cytotoxicity testing exhibited negligible cytotoxicity of as-prepared PVP-CoFe2O4 even at the concentration as high as 150 μg/mL after 24 h treatment. Considering the superparamagnetic properties, hydrophilic character and negligible cytotoxicity, the monodisperse CoFe2O4 nanoparticles hold great potential in a variety of biomedical applications.

  2. Magnetic CoFe2O4 nanoparticles supported on titanate nanotubes (CoFe2O4/TNTs) as a novel heterogeneous catalyst for peroxymonosulfate activation and degradation of organic pollutants.

    PubMed

    Du, Yunchen; Ma, Wenjie; Liu, Pingxin; Zou, Bohua; Ma, Jun

    2016-05-01

    Magnetic spinel ferrites, as heterogeneous catalysts to generate powerful radicals from peroxymonosulfate (PMS) for the degradation of organic pollutants, have received much attention in recent years due to the characteristic of environmental benefits. In this study, with titanate nanotubes (TNTs) as catalyst support, a novel CoFe2O4/TNTs hybrid was constructed by an impregnation-calcination method. Characterization results revealed that TNTs support could promise small size and good dispersion of CoFe2O4 nanoparticles. Compared to the pure CoFe2O4, the as-prepared CoFe2O4/TNTs not only exhibited better performance in catalytic decomposition of Rhodamine B, but also realized higher total organic carbon removal and less cobalt leaching, which could be attributed to the enhanced catalytic ability from smaller CoFe2O4 nanoparticles and the unique ion-exchange ability from TNTs support. Some influential factors, including reaction temperature, dosages of PMS and CoFe2O4/TNTs, and pH values were investigated and analyzed. Moreover, CoFe2O4/TNTs maintained its catalytic efficiency during the repeated batch experiments and also displayed functional advantages in the catalytic degradation of phenol. We believe the CoFe2O4/TNTs hybrid can be an efficient and green heterogeneous catalyst for the degradation of organic pollutants, and this study provides insights into the rational design and development of alternative catalysts for wastewater treatment. PMID:26808243

  3. Polyethylene glycol coated CoFe2O4 nanoparticles: A potential spinel ferrite for biomedical applications

    NASA Astrophysics Data System (ADS)

    Humbe, Ashok V.; Birajdar, Shankar D.; Bhandari, J. M.; Waghule, N. N.; Bhagwat, V. R.; Jadhav, K. M.

    2015-06-01

    The structural and magnetic properties of the polyethylene glycol (PEG) coated cobalt spinel ferrite (CoFe2O4) nanoparticles have been reported in the present study. CoFe2O4 nanoparticles were prepared by sol-gel auto-combustion method using citric acid + ethylene glycol as a fuel. The prepared powder of cobalt ferrite nanoparticles was annealed at 600°C for 6h and used for further study. The structural characterization of CoFe2O4 nanoparticles were carried out by X-ray diffraction technique. The X-ray analysis confirmed the formation of single phase cubic spinel structure. The crystallite size, Lattice constant and X-ray density of the PEG coated CoFe2O4 nanoparticles were calculated by using XRD data. The presence of PEG on CoFe2O4 nanoparticles and reduced agglomeration in the CoFe2O4 nanoparticles were revealed by SEM studies. The magnetic properties were studied by pulse field hysteresis loop tracer technique at a room temperature. The magnetic parameters such as saturation magnetization, remanence magnetization, coercivity etc have been obtained. These magnetic parameters were get decreased by PEG coating.

  4. Dynamics of CoFe2O4 Single-Core Nanoparticles in Viscoelastic Media

    NASA Astrophysics Data System (ADS)

    Remmer, Hilke; Dieckhoff, Jan; Tschöpe, Andreas; Roeben, Eric; Schmidt, Annette M.; Ludwig, Frank

    The dynamics of single-core CoFe2O4 nanoparticles in viscoelastic media was studied utilizing ac susceptibility and fluxgate magnetorelaxometry measurements. As viscoelastic medium aqueous gelatin suspensions with gelatin contents between 2.5 wt% and 10 wt% were used. Specifically, the gelation kinetics after cooling the sample from the sol state (313 K) to 296 K was investigated. It is shown that the measurement results can be analyzed with the Voigt-Kelvin model thus providing information on local dynamic viscosity and shear modulus.

  5. Feasibility of TEOS coated CoFe2O4 nanoparticles to a GMR biosensor agent for single molecular detection.

    PubMed

    Tang, Shao Qiang; Moon, Seung Je; Park, Ki Ho; Paek, Sun Ha; Chung, Kyung-Won; Bae, Seongtae

    2011-01-01

    Magnetic properties of 200 nm ferrimagnetic CoFe2O4 nanoparticles before and after coating with TEOS were explored and compared to soft ferrimagnetic MgFe2O4 nanoparticles (200 nm) to evaluate the feasibility as an in-vitro GMR SV (giant magnetoresistance spin-valve) biosensor agent for single molecular detection (SMD). It was found that the magnetic degradation (or variation) of TEOS coated CoFe2O4 and MgFe2O4 nanoparticles are dominantly affected by the chemical dispersion process, which is carried out in the oleic acid (OA), oleylamine (OL), or OA+OL surfactant, before starting major coating process. In addition, the TEOS coating thickness controlled by TEOS concentration and pH level in the buffer solution prominently influenced on the magnetic degradation of TEOS coated nanoparticles. According to the experimental analysis results, the magnetic degradation of TEOS coated nanoparticles is mainly attributed to the variation of particle dipole interaction caused by the degree of particle aggregation depending on TEOS coating process conditions. The TEOS coated CoFe2O4 nanoparticles exhibited a higher magnetic stability for a GMR biosensor agent, e.g., small variation of remnant magnetization, saturation magnetization and magnetic coercivity, than that of MgFe2O4 nanoparticles at the different coating process conditions. The physical and chemical analysis confirmed that this is primarily due to its higher magnetic anisotropy. The experimentally verified high biocompatibility as well as the stably maintained magnetic properties of TEOS coated CoFe2O4 nanoparticles demonstrate that CoFe2O4 nanoparticles can be considered as one of the promising ferrimagnetic nanoparticle sensor agent for an SMD GMR SV biosensor. PMID:21446410

  6. Significantly improved dehydrogenation of ball-milled MgH2 doped with CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Shan, Jiawei; Li, Ping; Wan, Qi; Zhai, Fuqiang; Zhang, Jun; Li, Ziliang; Liu, Zhaojiang; Volinsky, Alex A.; Qu, Xuanhui

    2014-12-01

    CoFe2O4 nanoparticles are added to magnesium hydride (MgH2) by high-energy ball milling in order to improve its hydriding properties. The hydrogen storage properties and catalytic mechanism are investigated by pressure-composition-temperature (PCT), differential thermal analysis (DTA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The nonisothermal desorption results show that the onset desorption temperature of the MgH2 + 7 mol% CoFe2O4 is 160 °C, which is 200 °C lower than of the as-received MgH2. The dehydrogenation process of the MgH2 doped with the CoFe2O4 nanoparticles includes two steps. DTA curves and XRD patterns reveal that a chemical reaction happens between MgH2 and CoFe2O4, forming the final products of the ternary combination, corresponding to Co3Fe7, MgO and Co. The onset desorption temperature of the ball-milled MgH2 doped with Co3Fe7, MgO and Co is about 260 °C, approximately 100 °C lower than the un-doped MgH2, demonstrating that the ternary combination (Co3Fe7, MgO, and Co) also has a great catalytic effect on the MgH2 hydrogen storage properties. It is also confirmed that the various methods of adding the ternary combination have different effects on the MgH2 hydriding-dehydriding process.

  7. Synthesis of patterned nanogold and mesoporous CoFe2O4 nanoparticle assemblies and their application in clinical immunoassays

    NASA Astrophysics Data System (ADS)

    Liu, Bingqian; Li, Qunfang; Zhang, Bing; Cui, Yuling; Chen, Huafeng; Chen, Guonan; Tang, Dianping

    2011-05-01

    Herein, we describe a facile and feasible synthesis method for patterning nanogold particles onto magnetic mesoporous CoFe2O4 nanostructures (Au-MMNs) by using poly(vinyl pyrrolidone) (PVP) as cross-linker. Initially, mesoporous CoFe2O4 nanoparticles were initially synthesized with a thermal decomposition method by using mesoporous silica nanoparticles as templates, and then nanometre-sized gold particles were produced through the in situ reduction of the AuIII on the PVP-functionalized CoFe2O4. The as-prepared Au-MMNs were characterized by transmission electron microscopy (TEM), N2 adsorption-desorption isotherms, UV-visible adsorption spectrometer, vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). Furthermore, we also demonstrate the conjugation capacity of the synthesized Au-MMNs toward biomolecules by using quartz crystal microbalance (QCM), and the possible application in the electrochemical immunoassays. Experimental results indicated that the resulting Au-MMNs display good conjugation capability toward the biomolecules, and excellent analytical properties for determination of target molecules.

  8. Effect of cobalt ferrite (CoFe2O4) nanoparticles on the growth and development of Lycopersicon lycopersicum (tomato plants).

    PubMed

    López-Moreno, Martha L; Avilés, Leany Lugo; Pérez, Nitza Guzmán; Irizarry, Bianca Álamo; Perales, Oscar; Cedeno-Mattei, Yarilyn; Román, Félix

    2016-04-15

    Nanoparticles (NPs) have been synthetized and studied to be incorporated in many industrial and medical applications in recent decades. Due to their different physical and chemical properties compared with bulk materials, researchers are focused to understand their interactions with the surroundings. Living organisms such as plants are exposed to these materials and they are able to tolerate different concentrations and types of NPs. Cobalt ferrite (CoFe2O4) NPs are being studied for their application in medical sciences because of their high coercivity, anisotropy, and large magnetostriction. These properties are desirable in magnetic resonance imaging, drug delivery, and cell labeling. This study is aimed to explore the tolerance of Solanum lycopersicum L. (tomato) plants to CoFe2O4 NPs. Tomato plants were grown in hydroponic media amended with CoFe2O4 nanoparticles in a range from 0 to 1000mgL(-1). Exposure to CoFe2O4 NPs did not affect germination and growth of plants. Uptake of Fe and Co inside plant tissues increased as CoFe2O4 nanoparticle concentration was increased in the media. Mg uptake in plant leaves reached its maximum level of 4.9mgg(-1) DW (dry weight) at 125mgL(-1) of CoFe2O4 NPs exposure and decreased at high CoFe2O4 NPs concentrations. Similar pattern was observed for Ca uptake in leaves where the maximum concentration found was 10mgg(-1) DW at 125mgL(-1) of CoFe2O4 NPs exposure. Mn uptake in plant leaves was higher at 62.5mgL(-1) of CoFe2O4 NPs compared with 125 and 250mgL(-1) treatments. Catalase activity in tomato roots and leaves decreased in plants exposed to CoFe2O4 NPs. Tomato plants were able to tolerate CoFe2O4 NPs concentrations up to 1000mgL(-1) without visible toxicity symptoms. Macronutrient uptake in plants was affected when plants were exposed to 250, 500 and 1000mgL(-1) of CoFe2O4 NPs.

  9. The Influence of Chelating Agent on the Structural and Magnetic Properties of CoFe2O4, Nanoparticles.

    PubMed

    Pedra, P P; Silva Filho, J L; Lima, R J S; Sharma, S K; Moura, K O; Duque, J G S; Meneses, C T

    2016-05-01

    We have studied the influence of chelating agents (glycerin and sucrose) on the structural and magnetic properties of cobalt ferrite (CoFe2O4) nanoparticles synthesized via co-precipitation method. The Rietveld refinements from X-ray diffraction patterns confirm that all samples are single phase identified in a cubic crystalline system belonging to the space group Fd-3m. Besides, we have verified that the addition of chelating agents produces a decreasing in the particles average size from 14(2) to 5(1) nm. Magnetization measurements as a function of temperature show a decrease in the blocking temperature (T(B)) to sample obtained with addition of sucrose. A superparamagnetic behavior at room temperature was observed by magnetic measurements as function of field in the sample with 0.020 mol/L of sucrose. The results show that character chelating of sucrose reduces the coalescence effect and magnetic interaction in the CoFe2O4 nanoparticles. These results suggest that sucrose could be an alternative to control the structural and magnetic properties of other oxides nanoparticles. PMID:27483850

  10. Surface spin effects in La-doped CoFe2O4 nanoparticles prepared by microemulsion route

    NASA Astrophysics Data System (ADS)

    Burianova, Simona; Poltierova Vejpravova, Jana; Holec, Petr; Plocek, Jiri; Niznansky, Daniel

    2011-10-01

    A comparative study of pure CoFe2O4 nanoparticles and La-doped CoFe2O4 nanoparticles, prepared by microemulsion route has been performed. The samples were characterized using x-ray diffraction and transmission electron microscopy in order to obtain average particle size. The doping of small amount of La3+ ions (up to 3 molar %) causes significant reduction of the particle size using the identical preparation route. The samples were investigated by magnetization measurements, which revealed the coercivity values strongly dependent on particle size, but not significantly on level of La3+ doping. Detailed in-field Mössbauer spectroscopy studies were performed in order to determine spin canting angles and cation distribution within the spinel network. The non-negligible canting angles up to 40° in the La-doped samples were observed. The presence of the spin surface effects was also supported by magnetic measurement as the magnetization did not saturate even in considerably high magnetic fields (7 T). Moreover, significantly reduced values of the saturation magnetization were obtained. The observed features originated by the surface spin disorder in nanosized particles are explained in the frame of the core-shell model.

  11. Effective approach towards Si-bilayer-IDA modified CoFe2O4 magnetic nanoparticles for high efficient protein separation.

    PubMed

    Li, Jianhao; Chen, Mengjun; Gao, Zhuo; Du, Jie; Yang, Wantai; Yin, Meizhen

    2016-10-01

    Ultrafine cobalt ferrite (CoFe2O4) nanoparticles with narrow size distributions and regular morphologies were prepared through an improved procedure based on the high-temperature diol reduction method. By replacing the original reducing agent like expensive dihydric alcohol, oleylamine was applied as both stabilizer and reducing agent, which benefit for large scale synthesis of magnetic CoFe2O4 nanoparticles. To produce protein-separation agent with both high specific surface area and magnet content, inverse microemulsion system and substitution reaction were employed to render the produced CoFe2O4 nanoparticles with dense silica bilayer and iminodiacetic acid (IDA)-like structure modification. After the chelation with Cu(2+), the metal-immobilized CoFe2O4 nanoparticles can specifically absorb bovine hemoglobin (BHb) with maximum adsorption capacity as qm=1812.3mg/g. Compared with the reported Cu(2+)-immobilized magnetic nanoparticles, the as-prepared CoFe2O4@Si-IDA-Cu(2+) nanoparticles exhibited excellent adsorption capacity and were applied as high efficient protein separation agent in a real complex biological fluid like bovine blood. PMID:27400241

  12. Effective approach towards Si-bilayer-IDA modified CoFe2O4 magnetic nanoparticles for high efficient protein separation.

    PubMed

    Li, Jianhao; Chen, Mengjun; Gao, Zhuo; Du, Jie; Yang, Wantai; Yin, Meizhen

    2016-10-01

    Ultrafine cobalt ferrite (CoFe2O4) nanoparticles with narrow size distributions and regular morphologies were prepared through an improved procedure based on the high-temperature diol reduction method. By replacing the original reducing agent like expensive dihydric alcohol, oleylamine was applied as both stabilizer and reducing agent, which benefit for large scale synthesis of magnetic CoFe2O4 nanoparticles. To produce protein-separation agent with both high specific surface area and magnet content, inverse microemulsion system and substitution reaction were employed to render the produced CoFe2O4 nanoparticles with dense silica bilayer and iminodiacetic acid (IDA)-like structure modification. After the chelation with Cu(2+), the metal-immobilized CoFe2O4 nanoparticles can specifically absorb bovine hemoglobin (BHb) with maximum adsorption capacity as qm=1812.3mg/g. Compared with the reported Cu(2+)-immobilized magnetic nanoparticles, the as-prepared CoFe2O4@Si-IDA-Cu(2+) nanoparticles exhibited excellent adsorption capacity and were applied as high efficient protein separation agent in a real complex biological fluid like bovine blood.

  13. The enhanced microwave absorption property of CoFe(2)O(4) nanoparticles coated with a Co(3)Fe(7)-Co nanoshell by thermal reduction.

    PubMed

    Xi, Li; Wang, Zhen; Zuo, Yalu; Shi, Xiaoning

    2011-01-28

    CoFe(2)O(4) nanoparticles were fabricated by a sol-gel method and then were coated with Co(3)Fe(7)-Co by means of a simple reduction process at different temperatures under 2% H(2) with the protection of argon to generate the dielectric-core/metallic-shell structure. The optimum reflection loss (RL) calculated from permittivity and permeability of the 80 wt% CoFe(2)O(4)/Co(3)Fe(7)-Co and 20 wt% epoxy resin composites reached - 34.4 dB, which was much lower than that of unreduced CoFe(2)O(4) and epoxy resin composites, at 2.4 GHz with a matching thickness of 4.0 mm. Moreover the RL exceeding - 10 dB in the maximum frequency range of 2.2-16 GHz was achieved for a thickness of composites of 1.0-4.5 mm with 600 °C thermal reduction process. The improved microwave absorption properties are a consequence of a proper electromagnetic match and the enhanced magnetic loss besides its dielectric loss due to the existence of the core/shell structure in CoFe(2)O(4) composites. Thus, the reductive CoFe(2)O(4) nanoparticles have great potential for being a highly efficient microwave absorber.

  14. Canted spin structure and the first order magnetic transition in CoFe2O4 nanoparticles coated by amorphous silica

    NASA Astrophysics Data System (ADS)

    Lyubutin, I. S.; Starchikov, S. S.; Gervits, N. E.; Korotkov, N. Yu.; Dmitrieva, T. V.; Lin, Chun-Rong; Tseng, Yaw-Teng; Shih, Kun-Yauh; Lee, Jiann-Shing; Wang, Cheng-Chien

    2016-10-01

    The functional polymer (PMA-co-MAA) latex microspheres were used as a core template to prepare magnetic hollow spheres consisting of CoFe2O4/SiO2 composites. The spinel type crystal structure of CoFe2O4 ferrite is formed under annealing, whereas the polymer cores are completely removed after annealing at 450 °C. Magnetic and Mössbauer spectroscopy measurements reveal very interesting magnetic properties of the CoFe2O4/SiO2 hollow spheres strongly dependent on the particle size which can be tuned by the annealing temperature. In the ground state of low temperatures, the CoFe2O4 nanoparticles are in antiferromagnetic state due to the canted magnetic structure. Under heating in the applied field, the magnetic structure gradually transforms from canted to collinear, which increases the magnetization. The Mössbauer data revealed that the small size CoFe2O4/SiO2 particles (2.2-4.3 nm) do not show superparamagnetic behavior but transit from the magnetic to the paramagnetic state by a jump-like magnetic transition of the first order This effect is a specific property of the magnetic nanoparticles isolated by inert material, and can be initiated by internal pressure creating at the particle surface. The suggested method of synthesis can be modified with various bio-ligands on the silane surface, and such materials can find many applications in diagnostics and bio-separation.

  15. Bioavailability of cobalt and iron from citric-acid-adsorbed CoFe2O4 nanoparticles in the terrestrial isopod Porcellio scaber.

    PubMed

    Romih, Tea; Drašler, Barbara; Jemec, Anita; Drobne, Damjana; Novak, Sara; Golobič, Miha; Makovec, Darko; Susič, Robert; Kogej, Ksenija

    2015-03-01

    The aim of this study was to determine whether citric acid adsorbed onto cobalt ferrite (CoFe2O4) nanoparticles (NPs) influences the bioavailability of their constituents Co and Fe. Dissolution of Co and Fe was assessed by two measures: (i) in aqueous suspension using chemical analysis, prior to application onto the food of test organisms; and (ii) in vivo, measuring the bioavailability in the model terrestrial invertebrate (Porcellio scaber, Isopoda, Crustacea). The isopods were exposed to citric-acid-adsorbed CoFe2O4 NPs for 2 weeks, and tissue accumulation of Co and Fe was assessed. This was compared to pristine CoFe2O4 NPs, and CoCl2 and Fe(III) salts as positive controls. The combined data shows that citric acid enhances free metal ion concentration from CoFe2O4 NPs in aqueous suspension, although in vivo, very similar amounts of assimilated Co were found in isopods exposed to both types of NPs. Therefore, evaluation of the dissolution in suspension by chemical means is not a good predictor of metal assimilation of this model organism; body assimilation of Co and Fe is rather governed by the physiological capacity of P. scaber for the uptake of these metals. Moreover, we propose that citric acid, due to its chelating properties, may hinder the uptake of Co that dissolves from citric-acid-adsorbed CoFe2O4 NPs, if citric acid is present in sufficient quantity.

  16. Magnetic and Mössbauer spectroscopy studies of hollow microcapsules made of silica-coated CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Lyubutin, I. S.; Gervits, N. E.; Starchikov, S. S.; Lin, Chun-Rong; Tseng, Yaw-Teng; Shih, Kun-Yauh; Wang, Cheng-Chien; Chen, I.-Han; Ogarkova, Yu L.; Korotkov, N. Yu

    2016-01-01

    The hollow microcapsules made of silica-coated CoFe2O4 nanoparticles were synthesized using chemical co-precipitation, followed by the sol-gel method. Poly(MMA-co-MAA) microspheres were used as a core template which can be completely removed after annealing at 450 °C. The microcapsules are monodisperse with the outer diameter of about 450 nm and the thickness of the shell is about 50 nm. The nanoparticles of Co-ferrite are single crystalline. The size of the nanoparticles and magnetic properties of CoFe2O4/SiO2 hollow spheres can be tuned with high accuracy at the annealing stage. The Mössbauer data indicate that CoFe2O4 ferrite is an inverse spinel, in which Fe3+ and Co2+ ions are distributed in both octahedral and tetrahedral sites with the inversion degree close to the bulk ferrite value. At low temperature the CoFe2O4/SiO2 nanoparticles are in antiferromagnetic (AFM) state due to the canted or triangular magnetic structure. Under heating in the applied field, AFM structure transforms to the ferrimagnetic (FM) structure, that increases the magnetization. The Mössbauer data revealed that the small size CoFe2O4/SiO2 particles do not show superparamagnetic behavior, but they transit to the paramagnetic state by the jump-like first order magnetic transition (JMT). This effect is a specific property of the magnetic nanoparticles isolated by inert material. The suggested method of synthesis can be modified with various bio-ligands on the silane surface, and such materials can find many applications in diagnostics and bio-separation.

  17. Quasi-static magnetic properties and high-frequency energy losses in CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Tykhonenko-Polishchuk, Yu. O.; Kulyk, N. N.; Yelenich, O. V.; Bečyte, V.; Mažeika, K.; Kalita, V. M.; Belous, A. G.; Tovstolytkin, A. I.

    2016-06-01

    Two series of nanosized cobalt spinel ferrites CoFe2O4 are synthesized from metal salts using high-energy ball milling with the addition of NaCl as a growth agent (series CFO-NaCl), and without (CFO Series). The particle properties are characterized using atomic force microscopy, as well as magnetic and calorimetric measurements. It is shown that the average sizes of the nanoparticles were ˜5.6 and ˜10.3 nm for CFO and CFO-NaCl series, respectively. We performed magnetostatic measurements and determined the parameters that are required to analyze the magnetic state and remagnetization processes of the nanoparticles. It is shown that the blocking temperature is ≈160 K for CFO samples and ≈300 K for the CFO-NaCl series. It was concluded that at 293 K the CFO series particles exhibit a superparamagnetic state, whereas the CFO-NaCl series are in the blocked state. The specific loss power that is scattered by the synthesized nanoparticle ensembles placed in an alternating magnetic field, is measured experimentally and theoretically assessed. The nature of the processes that determine the thermal characteristics of the nanoparticles is analyzed.

  18. Immobilization of glucose oxidase using CoFe2O4/SiO2 nanoparticles as carrier

    NASA Astrophysics Data System (ADS)

    Wang, Hai; Huang, Jun; Wang, Chao; Li, Dapeng; Ding, Liyun; Han, Yun

    2011-04-01

    Aminated-CoFe2O4/SiO2 magnetic nanoparticles (NPs) were prepared from primary silica particles using modified StÖber method. Glucose oxidase (GOD) was immobilized on CoFe2O4/SiO2 NPs via cross-linking with glutaraldehyde (GA). The optimal immobilization condition was achieved with 1% (v/v) GA, cross-linking time of 3 h, solution pH of 7.0 and 0.4 mg GOD (in 3.0 mg carrier). The immobilized GOD showed maximal catalytic activity at pH 6.5 and 40 °C. After immobilization, the GOD exhibited improved thermal, storage and operation stability. The immobilized GOD still maintained 80% of its initial activity after the incubation at 50 °C for 25 min, whereas free enzyme had only 20% of initial activity after the same incubation. After kept at 4 °C for 28 days, the immobilized and free enzyme retained 87% and 40% of initial activity, respectively. The immobilized GOD maintained approximately 57% of initial activity after reused 7 times. The KM (Michaelis-Menten constant) values for immobilized GOD and free GOD were 14.6 mM and 27.1 mM, respectively.

  19. Synthesis of well-dispersed magnetic CoFe2O4 nanoparticles in cellulose aerogels via a facile oxidative co-precipitation method.

    PubMed

    Wan, Caichao; Li, Jian

    2015-12-10

    With the increasing emphasis on green chemistry, it is becoming more important to develop environmentally friendly matrix materials for the synthesis of nanocomposites. Cellulose aerogels with hierarchical micro/nano-scale three-dimensional network beneficial to control and guide the growth of nanoparticles, are suitable as a class of ideal green nanoparticles hosts to fabricate multifunctional nanocomposites. Herein, a facile oxidative co-precipitation method was carried out to disperse CoFe2O4 nanoparticles in the cellulose aerogels matrixes, and the cellulose aerogels were prepared from the native wheat straw based on a green NaOH/polyethylene glycol solution. The mean diameter of the well-dispersed CoFe2O4 nanoparticles in the hybrid aerogels is 98.5 nm. Besides, the hybrid aerogels exhibit strong magnetic responsiveness, which could be flexibly actuated by a small magnet. And this feature also makes this class of magnetic aerogels possibly useful as recyclable adsorbents and some magnetic devices. Meanwhile, the mild green preparation method could also be extended to fabricate other miscellaneous cellulose-based nanocomposites.

  20. The effect of surface modification on the magnetic properties of CoFe2O4 nano-particles synthesized by the hydrothermal method.

    PubMed

    Zhang, Yue; Fei, Chunlong; Liu, Yong; Wang, Rongjuan; Yan, Gaolin; Xiong, Rui; Shi, Jing

    2010-10-01

    Cobalt ferrite (CoFe2O4) nano-particles were synthesized by the hydrothermal method with the addition of a surfactant sodium bis(2-ethylhexyl) sulphosuccinate (AOT). Characterization measurements including X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy showed that all the final products were single-phase CoFe2O4 nano-crystals with AOT molecules bonding to the surfaces, the average crystallite sizes were all near 25 nm, and the lattice constant increased with the increasing mass of AOT. The magnetic hysteresis loops measured at room temperature indicated that the bonding of the AOT to the surfaces led to an increase of the saturation magnetization (Ms), the coercivity (Hc) and the remanence ratio (Mr/Ms). Furthermore, as the concentration of AOT reached the critical micelle concentration (CMC), turning points were observed in the the curves of Hc, Mr/Ms and K(eff) (effective magnetic anisotropy constants) versus. the mass of AOT due to the formation of the AOT micelles.

  1. The effect of poly vinyl alcohol (PVA) surfactant on phase formation and magnetic properties of hydrothermally synthesized CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Jalalian, M.; Mirkazemi, S. M.; Alamolhoda, S.

    2016-12-01

    Nanoparticles of CoFe2O4 were synthesized by hydrothermal process at 190 °C with and without poly vinyl alcohol (PVA) addition using treatment durations of 1.5-6 h. The synthesized powders were characterized with X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), Field emission scanning electron microscope (FESEM) and vibration sample magnetometer (VSM) techniques. XRD results show presence of CoFe2O4 as the main phase and Co3O4 as the lateral phase in some samples. The results show that in the samples synthesized without PVA addition considerable amount of lateral phase is present after 3 h of hydrothermal treatment while with PVA addition this phase is undetectable in the XRD patterns of the sample synthesized at the same conditions. Microstructural studies represent increasing of particle size with increasing of hydrothermal duration and formation of coarser particles with PVA addition. The highest maximum magnetization (Mmax) values in both of the samples that were synthesized with and without PVA addition are about 59 emu/g that were obtained after 4.5 h of hydrothermal treatment. Intrinsic coercive field (iHc) value of the sample without PVA addition increases from 210 to 430 Oe. While with PVA addition the iHc value changes from 83 Oe to 493 Oe. The mechanism of changes in Mmax and iHc values has been explained.

  2. The anomalous memory effect related to the relaxation of surface and core moments observed in well-dispersed CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Huang, S.; Ma, Y. Q.; Xu, S. T.

    2015-12-01

    Well-dispersed uniform cobalt ferrite nanoparticles were synthesized by thermal decomposition of a metal-organic salt in organic solvent with a high boiling point, and characterized by XRD, TEM and detailed magnetic measurements. The moments of CoFe2O4 nanoparticles consist of the core and canted surface moments below 200 K, and the exchange-coupling between the surface and core spins enhanced the remanence (Mr) to saturation (Ms) magnetization ratio (Mr/Ms) at the temperature of 10 K. Interestingly, the anomalous memory effect was observed in a broad temperature range which can be attributed to the relaxation of surface spins below 200 K and the one from the moments of magnetically ordered entity larger than one particle above 200 K.

  3. Comparison of the magnetic, radiolabeling, hyperthermic and biodistribution properties of hybrid nanoparticles bearing CoFe2O4 and Fe3O4 metal cores

    NASA Astrophysics Data System (ADS)

    Psimadas, D.; Baldi, G.; Ravagli, C.; Comes Franchini, M.; Locatelli, E.; Innocenti, C.; Sangregorio, C.; Loudos, G.

    2014-01-01

    Metal oxide nanoparticles, hybridized with various polymeric chemicals, represent a novel and breakthrough application in drug delivery, hyperthermia treatment and imaging techniques. Radiolabeling of these nanoformulations can result in new and attractive dual-imaging agents as well as provide accurate in vivo information on their biodistribution profile. In this paper a comparison study has been made between two of the most promising hybrid core-shell nanosystems, bearing either magnetite (Fe3O4) or cobalt ferrite (CoFe2O4) cores, regarding their magnetic, radiolabeling, hyperthermic and biodistribution properties. While hyperthermic properties were found to be affected by the metal-core type, the radiolabeling ability and the in vivo fate of the nanoformulations seem to depend critically on the size and the shell composition.

  4. Size-regulated group separation of CoFe2O4 nanoparticles using centrifuge and their magnetic resonance contrast properties

    PubMed Central

    2013-01-01

    Magnetic nanoparticle (MNP)-based magnetic resonance imaging (MRI) contrast agents (CAs) have been the subject of extensive research over recent decades. The particle size of MNPs varies widely and is known to influence their physicochemical and pharmacokinetic properties. There are two commonly used methods for synthesizing MNPs, organometallic and aqueous solution coprecipitation. The former has the advantage of being able to control the particle size more effectively; however, the resulting particles require a hydrophilic coating in order to be rendered water soluble. The MNPs produced using the latter method are intrinsically water soluble, but they have a relatively wide particle size distribution. Size-controlled water-soluble MNPs have great potential as MRI CAs and in cell sorting and labeling applications. In the present study, we synthesized CoFe2O4 MNPs using an aqueous solution coprecipitation method. The MNPs were subsequently separated into four groups depending on size, by the use of centrifugation at different speeds. The crystal shapes and size distributions of the particles in the four groups were measured and confirmed by transmission electron microscopy and dynamic light scattering. Using X-ray diffraction analysis, the MNPs were found to have an inverse spinel structure. Four MNP groups with well-selected semi-Gaussian-like diameter distributions were obtained, with measured T2 relaxivities (r2) at 4.7 T and room temperature in the range of 60 to 300 mM−1s−1, depending on the particle size. This size regulation method has great promise for applications that require homogeneous-sized MNPs made by an aqueous solution coprecipitation method. Any group of the CoFe2O4 MNPs could be used as initial base cores of MRI T2 CAs, with almost unique T2 relaxivity owing to size regulation. The methodology reported here opens up many possibilities for biosensing applications and disease diagnosis. PACS 75.75.Fk, 78.67.Bf, 61.46.Df PMID:24004536

  5. Oleate-based hydrothermal preparation of CoFe2O4 nanoparticles, and their magnetic properties with respect to particle size and surface coating

    NASA Astrophysics Data System (ADS)

    Repko, Anton; Vejpravová, Jana; Vacková, Taťana; Zákutná, Dominika; Nižňanský, Daniel

    2015-09-01

    We present a facile and high-yield synthesis of cobalt ferrite nanoparticles by hydrothermal hydrolysis of Co-Fe oleate in the presence of pentanol/octanol/toluene and water at 180 or 220 °C. The particle size (6-10 nm) was controlled by the composition of the organic solvent and temperature. Magnetic properties were then investigated with respect to the particle size and surface modification with citric acid or titanium dioxide (leading to hydrophilic particles). The as-prepared hydrophobic nanoparticles (coated by oleic acid) had a minimum inter-particle distance of 2.5 nm. Their apparent blocking temperature (estimated as a maximum of the zero-field-cooled magnetization) was 180 K, 280 K and 330 K for the particles with size of 6, 9 and 10.5 nm, respectively. Replacement of oleic acid on the surface by citric acid decreased inter-particle distance to less than 1 nm, and increased blocking temperature by ca. 10 K. On the other hand, coating with titanium dioxide, supported by nitrilotri(methylphosphonic acid), caused increase of the particle spacing, and lowering of the blocking temperature by ca. 20 K. The CoFe2O4@TiO2 nanoparticles were sufficiently stable in water, methanol and ethanol. The particles were also investigated by Mössbauer spectroscopy and alternating-current (AC) susceptibility measurements, and their analysis with Vögel-Fulcher and power law. Effect of different particle coating and dipolar interactions on the magnetic properties is discussed.

  6. CoFe2O4 magnetic nanoparticles as a highly active heterogeneous catalyst of oxone for the degradation of diclofenac in water.

    PubMed

    Deng, Jing; Shao, Yisheng; Gao, Naiyun; Tan, Chaoqun; Zhou, Shiqing; Hu, Xuhao

    2013-11-15

    A magnetic nanoscaled catalyst cobalt ferrite (CoFe2O4) was successfully prepared and used for the activation of oxone to generate sulfate radicals for the degradation of diclofenac. The catalyst was characterized by transmission electron microscopy, X-ray diffractometry, Fourier transform infrared spectroscopy and vibrating sample magnetometer. The effects of calcination temperature, initial pH, catalyst and oxone dosage on the degradation efficiency were investigated. Results demonstrated that CoFe2O4-300 exhibited the best catalytic performance and almost complete removal of diclofenac was obtained in 15 min. The degradation efficiency increased with initial pH decreasing in the pH range of 5-9. The increase of catalyst and oxone dosage both had the positive effect on the degradation of diclofenac. Moreover, CoFe2O4 could retain high degradation efficiency even after being reused for five cycles. Finally, the major diclofenac degradation intermediates were identified and the primary degradation pathways were proposed. PMID:24140535

  7. Determination of Montelukast in Plasma Using β - Cyclodextrins Coated on CoFe2O4 Magnetic Nanoparticles in Luminol-H2O2 Chemiluminescence System Optimized by Doehlert Design.

    PubMed

    Samadi-Maybodi, Abdolraouf; Bakhtiar, Alireza; Fatemi, Mohammad Hossein

    2016-05-01

    A novel chemiluminescence method using β - cyclodextrins coated on CoFe2O4 magnetic nanoparticles is proposed for the chemiluminometric determination of montelukast in plasma. The effect of coated β - cyclodexterinon CoFe2O4 magnetic nanoparticles in the chemiluminescence of luminol-H2O2 system was investigated. It was found that β - cyclodexterin coated on CoFe2O4 magnetic nanoparticles could greatly enhance the chemiluminescence of the luminol-H2O2 system. Doehlert design was applied in order to optimize the number of experiments to be carried out to ascertain the possible interactions between the parameters and their effects on the chemiluminescence emission intensity. This design was selected because the levels of each variable may vary in a very efficient way with few experiments. Doehlert design and response surface methodology have been employed for optimization pH and concentrations of the components. Results showed under the optimized experimental conditions, the relative CL intensity (ΔI) is increased linearly in the concentration range of 0.003-0.586 μgml(-1) of montelukast with limit of detection (LOD) 1.09 × 10(-4) μgml(-1) at S/N ratio of 3, limit of quantitative (LOQ) 3.59 × 10(-4) μgml(-1) and the relative standard deviation 2.63 %. The method has been successfully applied to the determination of montelukast in plasma of human body. Results specified that relative chemiluminescence intensity (ΔI) has good proportional with the montelukast concentration with R(2) = 0.99979. The test of the recovery efficiency for known amounts of montelukast was also performed, the recoveries range obtained from 98.2 to 103.3 %, with RSDs of <4 % indicated that the proposed method was reliable. PMID:26979057

  8. Fatty acid as structure directing agent for controlled secondary growth of CoFe2O4 nanoparticles to achieve mesoscale assemblies: A facile approach for developing hierarchical structures

    NASA Astrophysics Data System (ADS)

    Saikia, K.; Kaushik, S. D.; Sen, D.; Mazumder, S.; Deb, P.

    2016-08-01

    Mesoscale hierarchical assemblies have emerged out as a new class of structures between fine dimension nanoparticles and bulk structures, having distinctly different physical properties from either side. Controlling the self-assembly process of primary nanoparticles and subsequent secondary growth mechanism is the key aspect for achieving such ordered structures. In this work, we introduce a new insight on achieving hierarchical assemblies of CoFe2O4 nanoparticles based on the temporal stability of the primary nanoparticles, where, the growth and stability of the primary particles are controlled by using oleic acid. It is found that the developed particles, at a critical concentration of oleic acid, prefer a secondary growth process, rather than promoting their individual growth. Domination of the attractive hydrophobic interaction over steric repulsion among the primary particles at this critical concentration of oleic acid is found to be the key factor for the initial aggregation of the primary particles, which eventually leads to the formation of spherical hierarchical assemblies via oriented attachment. It is also realized that the extremely well or poor stability conditions of the primary particles do not allow this secondary growth process. Estimated values of Co2+ distribution factor show that the cation distribution factor of CoFe2O4 system is not affected by the nature of dominant growth processes, when these are controlled. Interestingly, magnetic measurements reflect the stronger interparticle interaction in the hierarchical system and high magnetic moment values at low magnetic field.

  9. Morphology and magnetic properties of CoFe2O4 nanocables fabricated by electrospinning based on the Kirkendall effect

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengmei; Yang, Guijin; Wei, Jinxin; Bian, Haiqin; Gao, Jiming; Li, Jinyun; Wang, Tao

    2016-07-01

    CoFe2O4 nanocables have been successfully fabricated by electrospinning involving the nanoscale Kirkendall effect. The average diameters of the outer tubes and inner wires of CoFe2O4 nanocables are around 200 nm and 85 nm, respectively. The detailed formation process nanoscale morphology, structure and unique magnetic properties of CoFe2O4 nanocables have been studied comprehensively. Each fully calcined individual nanocable is composed of CoFe2O4 monocrystallites, which stacked along the longitudinal direction with random orientation. The coercivity (Hc) of the CoFe2O4 nanocables decreases from 11043 Oe at 10 K to 707 Oe at 300 K, and a spin reorientation has been detected at 5 K and 100 K, which is different from CoFe2O4 nanorods and nanoparticles.

  10. Preparation, characterization and catalytic activity of CoFe2O4 nanoparticles as a magnetically recoverable catalyst for selective oxidation of benzyl alcohol to benzaldehyde and reduction of organic dyes.

    PubMed

    Nasrollahzadeh, Mahmoud; Bagherzadeh, Mojtaba; Karimi, Hirbod

    2016-03-01

    The CoFe2O4 nanoparticles (NPs) performance was studied in the oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) with hydrogen peroxide as an oxidant under solvent-free conditions. The influences of reaction conditions like the amount of catalyst, the molar ratio of H2O2:BzOH, reaction temperature and times on the oxidation of BzOH by using CoFe2O4 NPs were investigated in details. Under optimum conditions, excellent result, >99% conversation of BzOH to BzH as the only product, was obtained. The nanocatalyst was also used for the reduction of 4-nitrophenol (4-NP), Congo red (CR), Methylene blue (MB) in water at room temperature. The magnetic properties of the catalyst provided a convenient and easy route for the separation of the catalyst from the reaction mixture by an external bar magnet. No obvious loss of activity was observed when the spent catalyst reused in three consecutive runs.

  11. Impact of ignition temperature on particle size and magnetic properties of CoFe2O4 nanoparticles prepared by self-propagated MILD combustion technique

    NASA Astrophysics Data System (ADS)

    Kaliyamoorthy, Venkatesan; Rajan Babu, D.; Saminathan, Madeswaran

    2016-11-01

    We prepared nanocrystalline CoFe2O4 by changing its ignition temperatures, using moderate and intense low-oxygen dilution (MILD) combustion technique. The effect of ignition temperature on the particle size and its magnetic behavior was investigated by HR-TEM and VSM respectively. We observed a vast change in the structural behavior and the magnetic properties of the prepared samples. X-ray diffraction studies revealed that the resultant samples had single phase with different grain sizes from 23±5 nm to 16±5 nm, which was understood by observing the growth of the grains through heat released from the combustion reaction. FE-SEM analysis showed high porosity with heterogeneous distribution of the pore size based on the adiabatic temperature and EPMA analysis, which confirmed the elemental compositions of the prepared samples. The saturation magnetization values measured at room temperature, employing vibrating sample magnetometer (VSM) decreased gradually from 50 to 34 emu/g when the ignition temperature was increased from 243 °C to 400 °C. Some of Fe ions on the B sites moved periodically to the A sites because of quenching treatment. The presence of Fe2+ ions in the existing ferrite structure ruled the magnetic behavior of the sample, as confirmed by the Mössbauer analysis.

  12. Facile synthesis and magnetorheological properties of superparamagnetic CoFe2O4/GO nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Guangshuo; Ma, Yingying; Dong, Xufeng; Tong, Yu; Zhang, Lina; Mu, Jingbo; Bai, Yongmei; Hou, Junxian; Che, Hongwei; Zhang, Xiaoliang

    2015-12-01

    In this study, cobalt ferrite/graphene oxide (CoFe2O4/GO) nanocomposites were synthesized successfully by a facile sonochemical method. The microstructure and physical properties of CoFe2O4/GO nanocomposites were investigated in detail by TEM, XRD and SQUID. It was found that GO nanosheets were fully exfoliated and decorated homogeneously with CoFe2O4 nanoparticles having diameters of 8∼15 nm. The field-dependent magnetization curve indicated superparamagnetic behavior of as-prepared CoFe2O4/GO with saturation magnetization (Ms) of 34.9 emu/g at room temperature. The ferrofluid was prepared by the obtained CoFe2O4/GO with 25 wt% particles and its magnetorheological (MR) properties were tested using a Physica MCR301 rheometer fitted with a magneto-rheological module. The CoFe2O4/GO-based ferrofluid exhibited typical MR effect with increasing viscosity, shear stress and yield stress depending on the applied magnetic field strength.

  13. Effect of Mn2+ doping and SiO2 coating on magneto-optical properties of CoFe2O4 nano-particles

    NASA Astrophysics Data System (ADS)

    Awad, Kamal R.; Wahsh, M. M. S.; Othman, A. G. M.; Girgis, E.; Mabrouk, M. R.; Morsy, Fatma A.

    2015-11-01

    Co1-xMnxFe2O4 (x = 0.2, 0.4, 0.6, 0.8, 1.0) magnetic nanoparticles were prepared using a modified citrate gel method and fired at 500 °C for 2 h. The modified Stöber method was used for coating the magnetic nanoparticles with a silica shell. The effects of Mn2+ substitution and the method of preparation on the formation of crystalline phases, particle size, morphology and the optical and magnetic properties of the synthesized materials were investigated by XRD, SAED, HR-TEM, EDX, UV/VIS double-beam spectrophotometry and vibrating sample magnetometry. The average crystallite size of the synthesized nanoparticles was 18.6-43.9 nm. The maximum value of saturation magnetization (Ms) achieved was 65.668 emu/g for Mn0.2Co0.8Fe2O4 nanoparticles. Diffuse reflectance increased with an increase of Mn2+content and SiO2 shell. These coated magnetic nanoparticles are promising materials for application to magnetic sensors and biomedical nanodevices.

  14. Effect of annealing on particle size, microstructure and gas sensing properties of Mn substituted CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Kumar, E. Ranjith; Kamzin, A. S.; Janani, K.

    2016-11-01

    Microstructure, morphological and gas sensor studies of Mn substituted cobalt ferrite nanoparticles synthesized by a simple evaporation method and auto- combustion method. The influence of heat treatment on phase and particle size of spinel ferrite nanoparticles were determined by X-ray diffraction and Mossbauer spectroscopy. The XRD study reveals that the lattice constant and crystallite size of the samples increases with the increase of annealing temperature. Last one was confirmed by Mossbauer data. The lowest size of particles of MnCoFe2O4 (~3 nm) is obtained by auto combustion method. The spherical shaped nanoparticles are recorded by TEM. Furthermore, conductance response of Mn-Co ferrite nanomaterial was measured by exposing the material to reducing gas like liquefied petroleum gas (LPG) which showed a sensor response of ~0.19 at an optimum operating temperature of 250 °C.

  15. Phase constituents and magnetic properties of the CoFe2O4 nanoparticles prepared by polyvinylpyrrolidone (PVP)-assisted hydrothermal route

    NASA Astrophysics Data System (ADS)

    Jalalian, M.; Mirkazemi, S. M.; Alamolhoda, S.

    2016-09-01

    In this research, nanoparticles of cobalt ferrite were synthesized by a simple hydrothermal process at 190 °C using different treatment durations with the assistance of polyvinylpyrrolidone (PVP) surfactant. The synthesized powders were characterized using X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscope and vibration sample magnetometer techniques. The quantitative values of phase constituents and also inversion parameter of cobalt ferrite spinel structure were calculated by Rietveld method using XRD results. XRD results show formation of cobalt ferrite as the main phase in all samples and also the presence of small amounts of Co3O4 lateral phase in some cases. Raman spectroscopies also confirm the presence of this lateral phase. Microstructural studies represent formation of nanoparticles with a narrow particle size distribution. Magnetic measurements represent that maximum magnetization ( M max) values are in the range of 25-57 emu/g with changes in the hydrothermal treatment duration. Intrinsic coercivity force values ( i H c ) change from 0 to 487 Oe in different samples. The highest M max value of 57 emu/g was obtained in the sample after 3 h of hydrothermal treatment with PVP addition. The i H c value of this sample was 35 Oe, while without PVP addition, the high M max value of 60 emu/g is observed in a sample that has i H c value equal to 320 Oe.

  16. Impact of Nd3+ in CoFe2O4 spinel ferrite nanoparticles on cation distribution, structural and magnetic properties

    NASA Astrophysics Data System (ADS)

    Yadav, Raghvendra Singh; Havlica, Jaromir; Masilko, Jiri; Kalina, Lukas; Wasserbauer, Jaromir; Hajdúchová, Miroslava; Enev, Vojtěch; Kuřitka, Ivo; Kožáková, Zuzana

    2016-02-01

    Nd3+ doped cobalt ferrite nanoparticles have been synthesized by starch-assisted sol-gel auto-combustion method. The significant role played by Nd3+ added to cobalt ferrite in changing cation distribution and further in influencing structural and magnetic properties, was explored and reported. The crystal structure formation and crystallite size were studied from X-ray diffraction studies. The microstructural features were investigated by field emission scanning electron microscopy and transmission electron microscopy that demonstrates the nanocrystalline grain formation with spherical morphology. An infrared spectroscopy study shows the presence of two absorption bands related to tetrahedral and octahedral group complexes within the spinel ferrite lattice system. The change in Raman modes in synthesized ferrite system were observed with Nd3+ substitution, particle size and cation redistribution. The impact of Nd3+ on cation distribution of Co2+ and Fe3+ at octahedral and tetrahedral sites in spinel ferrite cobalt ferrite nanoparticles was investigated by X-ray photoelectron spectroscopy. Room temperature magnetization measurements showed that the saturation magnetization and coercivity increase with addition of Nd3+ substitution in cobalt ferrite.

  17. Simultaneous effects of surface spins: rarely large coercivity, high remanence magnetization and jumps in the hysteresis loops observed in CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, S. T.; Ma, Y. Q.; Zheng, G. H.; Dai, Z. X.

    2015-04-01

    Well-dispersed uniform cobalt ferrite nanoparticles were synthesized by thermal decomposition of a metal-organic salt in organic solvent with a high boiling point. Some of the nanoparticles were diluted in a SiO2 matrix and then the undiluted and diluted samples were characterized and their magnetic behavior explored. The undiluted and diluted samples exhibited maximum coercivity Hc of 23 817 and 15 056 Oe at 10 K, respectively, which are the highest values reported to date, and the corresponding ratios of remanence (Mr) to saturation (Ms) magnetization (Mr/Ms) were as high as 0.85 and 0.76, respectively. Interestingly, the magnetic properties of the samples changed at 200 K, which was observed in magnetic hysteresis M(H) loops and zero-field cooling curves as well as the temperature dependence of Hc, Mr/Ms, anisotropy, dipolar field, and the magnetic grain size. Below 200 K, both samples have large effective anisotropy, which arises from the surface spins, resulting in large Hc and Mr/Ms. Above 200 K, the effective anisotropy decreases because there is no contribution from surface spins, while the dipolar interaction increases, resulting in small Hc and Mr/Ms. Our results indicate that strong anisotropy and weak dipolar interaction tend to increase Hc and Mr/Ms, and also clarify that the jumps around H = 0 in M(H) loops can be attributed to the reorientation of surface spins. This work exposes the underlying mechanism in nanoscale magnetic systems, which should lead to improved magnetic performance.

  18. Magnetoelectric CoFe2O4/polyvinylidene fluoride electrospun nanofibres

    NASA Astrophysics Data System (ADS)

    Gonçalves, R.; Martins, P.; Moya, X.; Ghidini, M.; Sencadas, V.; Botelho, G.; Mathur, N. D.; Lanceros-Mendez, S.

    2015-04-01

    Magnetoelectric 0-1 composites comprising CoFe2O4 (CFO) nanoparticles in a polyvinylidene fluoride (PVDF) polymer-fibre matrix have been prepared by electrospinning. The average diameter of the electrospun composite fibres is ~325 nm, independent of the nanoparticle content, and the amount of the crystalline polar β phase is strongly enhanced when compared to pure PVDF polymer fibres. The piezoelectric response of these electroactive nanofibres is modified by an applied magnetic field, thus evidencing the magnetoelectric character of the CFO/PVDF 0-1 composites.

  19. Microwave assisted combustion synthesis of nanocrystalline CoFe2O4 for LPG sensing

    NASA Astrophysics Data System (ADS)

    Chaudhari, Prashant; Acharya, S. A.; Darunkar, S. S.; Gaikwad, V. M.

    2015-08-01

    A microwave-assisted citrate precursor method has been utilized for synthesis of nanocrystalline powders of CoFe2O4. The process takes only a few minutes to obtain as-synthesized CoFe2O4. Structural properties of the synthesized material were investigated by X-ray diffraction; scanning electron microscopy, Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy. The gas sensing properties of thick film of CoFe2O4 prepared by screen printing towards Liquid Petroleum Gas (LPG) revealed that CoFe2O4 thick films are sensitive and shows maximum sensitivity at 350°C for 2500 ppm of LPG.

  20. Synthesis and characterization of superparamagnetic CoFe2O4/MWCNT hybrids for tumor-targeted therapy.

    PubMed

    Sun, Chuanyu; Liu, Yong; Ding, Weihong; Gou, Yuancheng; Xu, Ke; Xia, Guowei; Ding, Qiang

    2013-01-01

    Owing to their great potentialities of carbon nanotubes (CNTs)-based magnetic nano-composites, numerous applications of them have been found in nanotechnology, integrated functional system, and in medicine. Herein, nearly monodisperse CoFe2O4 nanoparticles have been deposited on multi-walled carbon nanotubes (MWCNTs) by high-temperature hydrolysis and inorganic polymerization of ionic Co(II) and Fe(III) salts and MWCNTs in a polyol solution. X-ray diffraction, energy-dispersive X-ray spectrometry and transmission electron microscopy were used to characterize the final products. The average size of CoFe2O4 nanoparticles and their coverage density on MWCNTs can be adjusted to some extent by altering the reaction parameters. A proposed formation mechanism of the magnetic hybrids is presented. Magnetic measurements showed that the hybrids were superparamagnetic at room temperature and their saturation magnetization could be fine tuned by changing the loading of CoFe2O4 nanoparticles on the MWCNTs.

  1. Microemulsion synthesis and magnetic properties of hydroxyapatite-encapsulated nano CoFe2O4

    NASA Astrophysics Data System (ADS)

    Foroughi, Firoozeh; Hassanzadeh-Tabrizi, S. A.; Amighian, Jamshid

    2015-05-01

    Hydroxyapatite-encapsulated cobalt ferrite (CoFe2O4) nanopowders were synthesized by one step microemulsion method. The powders were characterized by X-ray Diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometer. TEM results showed that nanoparticles calcined at 700 °C have core-shell morphology. It was found that the resultant phases, morphology and magnetic properties of the samples depend on calcining temperature. The synthesized nanoparticles showed a maximum saturation magnetization of 7.8 emu/g with a wasp-waisted hysteresis loop. The magnetion was reduced by increasing calcining temperature to 900 °C. This reduction is due to the reaction of cobalt ferrite with hydroxyapatite which leads to CaFe12(PO4)8(OH)12 phase.

  2. Magnetic Properties of CoFe_2O4 and Fe_3O_4

    NASA Astrophysics Data System (ADS)

    Rodriguez, Robert; Chan, T.; Kenning, G. G.; Huang, L.; Yan, Y.

    2002-03-01

    In order to optimize the magnetization of magnetic nanoparticles for use as Magnetic Resonance Imaging contrast agents and other in vivo biological applications, we have synthesized CoFe_2O_4(Liu, C.; Bingsuo, Z.; Rondinone, A.J.; Zhang, Z.J. J. Am. Chem. Soc.) 122, 6263 (2000). and Fe_3O_4(Shen, T.; Weissleder, R.; Papisov, M.; Bogdanov, A.; Brady, T. MRM) 29, 599 (1993). magnetic nanoparticles of sizes 5, 8, and 11nm using water-in-oil reverse micelles. Size was determined using Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD), and High Pressure Liquid Chromatography (HPLC). Magnetic properties were measure from 10K-340K using SQUID magnetometry. Magnetization as a function of magnetic field has been performed at approximately body temperature ( ~310K) in order to help us determine the optimal size and composition for in vivo application.

  3. A simple aloe vera plant-extracted microwave and conventional combustion synthesis: Morphological, optical, magnetic and catalytic properties of CoFe2O4 nanostructures

    NASA Astrophysics Data System (ADS)

    Manikandan, A.; Sridhar, R.; Arul Antony, S.; Ramakrishna, Seeram

    2014-11-01

    Nanocrystalline magnetic spinel CoFe2O4 was synthesized by a simple microwave combustion method (MCM) using ferric nitrate, cobalt nitrate and Aloe vera plant extracted solution. For the comparative study, it was also prepared by a conventional combustion method (CCM). Powder X-ray diffraction, energy dispersive X-ray and selected-area electron diffraction results indicate that the as-synthesized samples have only single-phase spinel structure with high crystallinity and without the presence of other phase impurities. The crystal structure and morphology of the powders were revealed by high resolution scanning electron microscopy and transmission electron microscopy, show that the MCM products of CoFe2O4 samples contain sphere-like nanoparticles (SNPs), whereas the CCM method of samples consist of flake-like nanoplatelets (FNPs). The band gap of the samples was determined by UV-Visible diffuse reflectance and photoluminescence spectroscopy. The magnetization (Ms) results showed a ferromagnetic behavior of the CoFe2O4 nanostructures. The Ms value of CoFe2O4-SNPs is higher i.e. 77.62 emu/g than CoFe2O4-FNPs (25.46 emu/g). The higher Ms value of the sample suggest that the MCM technique is suitable for preparing high quality nanostructures for magnetic applications. Both the samples were successfully tested as catalysts for the conversion of benzyl alcohol. The resulting spinel ferrites were highly selective for the oxidation of benzyl alcohol and exhibit important difference among their activities. It was found that CoFe2O4-SNPs catalyst show the best performance, whereby 99.5% selectivity of benzaldehyde was achieved at close to 93.2% conversion.

  4. Magnetic and elastic properties of CoFe2O4- polydimethylsiloxane magnetically oriented elastomer nanocomposites

    NASA Astrophysics Data System (ADS)

    Soledad Antonel, P.; Jorge, Guillermo; Perez, Oscar E.; Butera, Alejandro; Gabriela Leyva, A.; Martín Negri, R.

    2011-08-01

    Magnetic elastic structured composites were prepared by using CoFe2O4 ferromagnetic and superparamagnetic nanoparticles as fillers in polydimethylsiloxane (PDMS) matrixes, which were cured in the presence of a uniform magnetic field. Cobalt-iron oxide nanoparticles of three different average sizes (between 2 and 12 nm) were synthesized and characterized. The smallest nanoparticles presented superparamagnetic behavior, with a blocking temperature of approximately 75 K, while larger particles are already blocked at room temperature. Macroscopically structured-anisotropic PDMS-CoFe2O4 composites were obtained when curing the dispersion of the nanoparticles in the presence of a uniform magnetic field (0.3 T). The formation of the particle's chains (needles) orientated in the direction of the magnetic field was observed only when loading with the larger magnetically blocked nanoparticles. The SEM images show that the needles are formed by groups of nanoparticles which retain their original average size. The Young's moduli of the structured composites are four times larger when measured along the oriented needles than in the perpendicular direction. Magnetization (VSM) and ferromagnetic resonance curves of the structured composites were determined as a function of the relative orientation between the needles and the probe field. The remanence magnetization was 30% higher when measured parallel to the needles, while the coercive field remains isotropic. These observations are discussed in terms of the individual nanoparticle's properties and its aggregation in the composites.

  5. Synthesize and characterization of a novel anticorrosive cobalt ferrite nanoparticles dispersed in silica matrix (CoFe2O4-SiO2) to improve the corrosion protection performance of epoxy coating

    NASA Astrophysics Data System (ADS)

    Gharagozlou, M.; Ramezanzadeh, B.; Baradaran, Z.

    2016-07-01

    This study aimed at studying the effect of an anticorrosive nickel ferrite nanoparticle dispersed in silica matrix (NiFe2O4-SiO2) on the corrosion protection properties of steel substrate. NiFe2O4 and NiFe2O4-SiO2 nanopigments were synthesized and then characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscope (TEM). Then, 1 wt.% of nanopigments was dispersed in an epoxy coating and the resultant nanocomposites were applied on the steel substrates. The corrosion inhibition effects of nanopigments were tested by an electrochemical impedance spectroscopy (EIS) and salt spray test. Results revealed that dispersing nickel ferrite nanoparticles in a silica matrix (NiFe2O4-SiO2) resulted in the enhancement of the nanopigment dispersion in the epoxy coating matrix. Inclusion of 1 wt.% of NiFe2O4-SiO2 nanopigment into the epoxy coating enhanced its corrosion protection properties before and after scratching.

  6. Preparation and photocatalytic properties of nanometer-sized magnetic TiO2/SiO2/CoFe2O4 composites.

    PubMed

    Li, Hansheng; Zhang, Yaping; Wu, Qin; Wang, Xitao; Liu, Changhao

    2011-11-01

    Magnetic TiO2/SiO2/CoFe2O4 nanoparticles (TiO2/SCFs) were prepared by a sol-gel process in a reverse microemulsion combined with solvent-thermal technique. TiO2/SCFs were characterized by Fourier transform infrared spectrometry, thermogravimetric analysis-differential scanning calorimetry, X-ray diffraction, Raman spectrometry, TEM, BET specific surface area measurement, and magnetic analysis. Structure analyses indicated that TiO2/SCFs presented a core-shell structure with TiO2 uniformly coating on SiO2/CoFe2O4 nanomagnets (SCFs) and typical ferromagnetic hysteresis. TiO2/SCFs showed larger specific surface area and better photocatalytic activities than TiO2 and TiO2/CoFe2O4 photocatalysts prepared by the same method. The doping interaction between TiO2 and CoFe2O4 reduced thanks to the inert SiO2 mesosphere.

  7. Structural and magnetic properties of turmeric functionalized CoFe2O4 nanocomposite powder

    NASA Astrophysics Data System (ADS)

    Mehran, E.; Farjami Shayesteh, S.; Sheykhan, M.

    2016-10-01

    The structural and magnetic properties of the synthesized pure and functionalized CoFe2O4 magnetic nanoparticles (NPs) are studied by analyzing the results from the x-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR spectroscopy, thermogravimetry (TG), and vibrating sample magnetometer (VSM). To extract the structure and lattice parameters from the XRD analysis results, we first apply the pseudo-Voigt model function to the experimental data obtained from XRD analysis and then the Rietveld algorithm is used in order to optimize the model function to estimate the true intensity values. Our simulated intensities are in good agreement with the experimental peaks, therefore, all structural parameters such as crystallite size and lattice constant are achieved through this simulation. Magnetic analysis reveals that the synthesized functionalized NPs have a saturation magnetization almost equal to that of pure nanoparticles (PNPs). It is also found that the presence of the turmeric causes a small reduction in coercivity of the functionalized NPs in comparison with PNP. Our TGA and FTIR results show that the turmeric is bonded very well to the surface of the NPs. So it can be inferred that a nancomposite (NC) powder of turmeric and nanoparticles is produced. As an application, the anti-arsenic characteristic of turmeric makes the synthesized functionalized NPs or NC powder a good candidate for arsenic removal from polluted industrial waste water. Project supported by the University of Guilan and the Iran Nanotechnology Initiative Council.

  8. Spin Hall magnetoresistance in CoFe2O4/Pt films

    DOE PAGES

    Wu, Hao; Qintong, Zhang; Caihua, Wan; Ali, Syed Shahbaz; Yuan, Zhonghui; You, Lu; Wang, Junling; Choi, Yongseong; Han, Xiufeng

    2015-05-13

    Pulse laser deposition and magnetron sputtering techniques have been employed to prepare MgO(001)//CoFe2O4/Pt samples. Cross section transmission electron microscope results prove that the CoFe2O4 film epitaxially grew along (001) direction. X-ray magnetic circular dichroism results show that magnetic proximity effect in this sample is negligible. Magnetoresistance (MR) properties confirm that spin Hall MR (SMR) dominates in this system. Spin Hall effect-induced anomalous Hall voltage was also observed in this sample. Lastly, these results not only demonstrate the universality of SMR effect but also demonstrate the utility in spintronics of CoFe2O4 as a new type of magnetic insulator.

  9. Magnetoelectricity in CoFe2O4 nanocrystal-P(VDF-HFP) thin films

    PubMed Central

    2013-01-01

    Transition metal ferrites such as CoFe2O4, possessing a large magnetostriction coefficient and high Curie temperature (Tc > 600 K), are excellent candidates for creating magnetic order at the nanoscale and provide a pathway to the fabrication of uniform particle-matrix films with optimized potential for magnetoelectric coupling. Here, a series of 0–3 type nanocomposite thin films composed of ferrimagnetic cobalt ferrite nanocrystals (8 to 18 nm) and a ferroelectric/piezoelectric polymer poly(vinylidene fluoride-co-hexafluoropropene), P(VDF-HFP), were prepared by multiple spin coating and cast coating over a thickness range of 200 nm to 1.6 μm. We describe the synthesis and structural characterization of the nanocrystals and composite films by XRD, TEM, HRTEM, STEM, and SEM, as well as dielectric and magnetic properties, in order to identify evidence of cooperative interactions between the two phases. The CoFe2O4 polymer nanocomposite thin films exhibit composition-dependent effective permittivity, loss tangent, and specific saturation magnetization (Ms). An enhancement of the effective permittivity and saturation magnetization of the CoFe2O4-P(VDF-HFP) films was observed and directly compared with CoFe2O4-polyvinylpyrrolidone, a non-ferroelectric polymer-based nanocomposite prepared by the same method. The comparison provided evidence for the observation of a magnetoelectric effect in the case of CoFe2O4-P(VDF-HFP), attributed to a magnetostrictive/piezoelectric interaction. An enhancement of Ms up to +20.7% was observed at room temperature in the case of the 10 wt.% CoFe2O4-P(VDF-HFP) sample. PMID:24004499

  10. Synthesis and characterization of Cr doped CoFe2O4

    NASA Astrophysics Data System (ADS)

    Verma, Kavita; Patel, K. R.; Ram, Sahi; Barbar, S. K.

    2016-05-01

    Polycrystalline samples of pure and Cr-doped cobalt ferrite (CoFe2O4 and CoCrFeO4) were prepared by solid state reaction route method. X-ray diffraction pattern infers that both the samples are in single phase with Fd3m space group. Slight reduction in the lattice parameter of CoCrFeO4 has been observed as compared to CoFe2O4. The dielectric dispersion has been explained on the basis of Fe2+ ↔ Fe3+ hopping mechanism. The polarizations at lower frequencies are mainly attributed to electronic exchange between Fe2+ ↔ Fe3+ ions on the octahedral site in the ferrite lattice. In the present system a part from n-type charge carrier (Fe3+/Fe2+), the presence of (Co3+/Co2+) ions give rise to p-type charge carrier. Therefore in addition to n-type charge carrier, the local displacement of p-type charge carrier in direction of external electric field also contributes to net polarization. However, the dielectric constant and loss tangent of CoCrFeO4 are found to be lower than CoFe2O4 and is attributed to the availability of ferrous ion. CoCrFeO4 have less amount of ferrous ion available for polarization as compared to that of CoFe2O4. The impedance spectra reveal a grain interior contribution to the conduction process.

  11. Synthesis and magnetic properties of spinel CoFe 2O 4 nanowire arrays

    NASA Astrophysics Data System (ADS)

    Yuan, J. J.; Zhao, Q.; Xu, Y. S.; Liu, Z. G.; Du, X. B.; Wen, G. H.

    2009-09-01

    Spinel CoFe 2O 4 nanowire arrays were synthesized in nanopores of anodic aluminum oxide (AAO) template using aqueous solution of cobalt and iron nitrates as precursor. The precursor was filled into the nanopores by vacuum impregnation. After heat treatment, it transformed to spinel CoFe 2O 4 nanowires. The structure, morphology and magnetic properties of the sample were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The results indicate that the nanowire arrays are compact. And the individual nanowires have a high aspect ratio, which are about 80 nm in diameter and 10 μm in length. The nanowires are polycrystalline spinel phase. Magnetic measurements indicate that the nanowire arrays are nearly magnetic isotropic. The reason is briefly discussed. Moreover, the temperature dependence of the coercive force of the nanowire arrays was studied.

  12. Flux growth of high-quality CoFe 2O 4 single crystals and their characterization

    NASA Astrophysics Data System (ADS)

    Wang, W. H.; Ren, X.

    2006-04-01

    We report the growth of high-quality CoFe 2O 4 single crystals using a borax flux method. The crystals were characterized by powder X-ray diffraction, electron probe microanalysis and Raman spectroscopy. We found the crystals are flux-free and highly homogeneous in composition. X-ray rocking curves of the CoFe 2O 4 single crystals showed a full-width at half-maximum of 0.15°. The saturation magnetization of the CoFe 2O 4 single crystals was measured to be 90 emu/g or equivalently 3.65 μ B/f.u. at 5 K.

  13. On the microstructural and magnetic properties of fine-grained CoFe2O4 ceramics produced by combining polyol process and spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Gaudisson, T.; Artus, M.; Acevedo, U.; Herbst, F.; Nowak, S.; Valenzuela, R.; Ammar, S.

    2014-12-01

    Starting from polyol-made CoFe2O4 ferrite nanoparticles of different aggregation states, high-density fine-grained ceramics were produced using Spark Plasma Sintering technique at 600 and 500 °C, under vacuum and applying a uniaxial pressure of more than 80 MPa. The grain growth of thus produced ceramics appears to be proportional to the temperature plateau and inversely proportional to the aggregation state of the initial powders. Average grain sizes ranging between about 50 and 350 nm were obtained. In all the cases, magnetic measurements evidenced a ferrimagnetic behavior at room temperature with non-zero coercivity, while their starting powders exhibited superparamagnetic features.

  14. Enhanced magnetic moment in ultrathin Fe-doped CoFe2O4 films

    NASA Astrophysics Data System (ADS)

    Moyer, J. A.; Vaz, C. A. F.; Kumah, D. P.; Arena, D. A.; Henrich, V. E.

    2012-11-01

    The effect of film thickness on the magnetic properties of ultrathin Fe-doped cobalt ferrite (Co1-xFe2+xO4) grown on MgO (001) substrates is investigated by superconducting quantum interference device magnetometry and x-ray magnetic linear dichroism, while the distribution of the Co2+ cations between the octahedral and tetrahedral lattice sites is studied with x-ray absorption spectroscopy. For films thinner than 10 nm, there is a large enhancement of the magnetic moment; conversely, the remanent magnetization and coercive fields both decrease, while the magnetic spin axes of all the cations become less aligned with the [001] crystal direction. In particular, at 300 K the coercive fields of the thinnest films vanish. The spectroscopy data show that no changes occur in the cation distribution as a function of film thickness, ruling this out as the origin of the enhanced magnetic moment. However, the magnetic measurements all support the possibility that these ultrathin Fe-doped CoFe2O4 films are transitioning into a superparamagnetic state, as has been seen in ultrathin Fe3O4. A weakening of the magnetic interactions at the antiphase boundaries, leading to magnetically independent domains within the film, could explain the enhanced magnetic moment in ultrathin Fe-doped CoFe2O4 and the onset of superparamagnetism at room temperature.

  15. Optimizing piezoelectric and magnetoelectric responses on CoFe2O4/P(VDF-TrFE) nanocomposites

    NASA Astrophysics Data System (ADS)

    Martins, P.; Lasheras, A.; Gutierrez, J.; Barandiaran, J. M.; Orue, I.; Lanceros-Mendez, S.

    2011-12-01

    Magnetoelectric (ME) nanocomposite films composed of magnetostrictive CoFe2O4 nanoparticles with sizes between 35 and 55 nm embedded in P(VDF-TrFE) have been successfully prepared by a solvent casting method. The ferroelectric, piezoelectric, magnetic and ME properties of the nanocomposite and their variation with the wt% of the ferrite filler, thickness of the composite and direction of the applied magnetic field have been investigated. Ferroelectric and piezoelectric properties were improved when a small amount of ferrite nanoparticles was added to the polymeric matrix. Magnetic properties vary linearity with ferrite content. The highest ME response of 41.3 mV cm-1 Oe-1 was found in the composite with 72 wt% when a 2.5 kOe DC field was transversely applied to the sample surface. This value is among the highest reported in two phase particulate polymer nanocomposites. Thickness of the composite has no influence in the ME response, allowing tailoring sensor thickness for specific applications. The good value of the ME coefficient and the flexibility of the films make these composites suitable for applications in ME smart devices.

  16. Research Update: Facile synthesis of CoFe2O4 nano-hollow spheres for efficient bilirubin adsorption

    NASA Astrophysics Data System (ADS)

    Rakshit, Rupali; Pal, Monalisa; Chaudhuri, Arka; Mandal, Madhuri; Mandal, Kalyan

    2015-11-01

    Herein, we report an unprecedented bilirubin (BR) adsorption efficiency of CoFe2O4 (CFO) nanostructures in contrast to the commercially available activated carbon and resin which are generally used for haemoperfusion and haemodialysis. We have synthesized CFO nanoparticles of diameter 100 nm and a series of nano-hollow spheres of diameter 100, 160, 250, and 350 nm using a simple template free solvothermal technique through proper variation of reaction time and capping agent, oleylamine (OLA), respectively, and carried out SiO2 coating by employing Stöber method. The comparative BR adsorption study of CFO and SiO2 coated CFO nanostructures indicates that apart from porosity and hollow configuration of nanostructures, the electrostatic affinity between anionic carboxyl group of BR and cationic amine group of OLA plays a significant role in adsorbing BR. Finally, we demonstrate that the BR adsorption capacity of the nanostructures can be tailored by varying the morphology as well as size of the nanostructures. We believe that our developed magnetic nanostructures could be considered as a potential material towards therapeutic applications against hyperbilirubinemia.

  17. Thermal generation of spin current in epitaxial CoFe2O4 thin films

    DOE PAGES

    Guo, Er -Jia; Herklotz, Andreas; Kehlberger, Andreas; Cramer, Joel; Jakob, Gerhard; Klaeui, Mathias

    2016-01-12

    The longitudinal spin Seebeck effect (LSSE) has been investigated in high-quality epitaxial CoFe2O4 (CFO) thin films. The thermally excited spin currents in the CFO films are electrically detected in adjacent Pt layers due to the inverse spin Hall effect (ISHE). The LSSE signal exhibits a linear increase with increasing temperature gradient, yielding a LSSE coefficient of –100 nV/K at room temperature. The temperature dependence of the LSSE is investigated from room temperature down to 30 K, showing a significant reduction at low temperatures, revealing that the total amount of thermally generated magnons decreases. Moreover, we demonstrate that the spin Seebeckmore » effect is an effective tool to study the magnetic anisotropy induced by epitaxial strain, especially in ultrathin films with low magnetic moments.« less

  18. A facile synthesis of encapsulated CoFe2O4 into carbon nanofibres and its application as conversion anodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Ren, Shuhua; Zhao, Xiangyu; Chen, Ruiyong; Fichtner, Maximilian

    2014-08-01

    CoFe2O4 nanoparticles anchored into in-situ formed carbon nanofibres were synthesized by a simple solvent-free and template-free pyrolysis-oxidation process and have been investigated as a promising anode material for Li-ion batteries. Ferrocene and cobaltocene as precursor materials, act as both metal and carbon sources. Carbon contents in the composite can be easily adjusted by varying oxidation conditions. The as-prepared composites show a high and stable capacity. More than 700 mAh g-1 based on the total mass of the as-prepared composite was obtained in the composite with 36% carbon content after long-term cycling of 250 cycles. The superior electrochemical properties are suggested to be benefited from the synergistic effects by combining CoFe2O4 and carbon and also their intimate contact developed in the synthetic process. This work opens a facile and broadly applicable way for fabrication and utilization of metal oxide/mixed metal oxide-carbon composites for Li-ion batteries.

  19. Thickness dependence of exchange coupling in epitaxial Fe3O4/CoFe2O4 soft/hard magnetic bilayers

    NASA Astrophysics Data System (ADS)

    Lavorato, G.; Winkler, E.; Rivas-Murias, B.; Rivadulla, F.

    2016-08-01

    Epitaxial magnetic heterostructures of (soft -) Fe3O4/(hard -) CoFe2O4(001 ) have been fabricated with a varying thicknesses of soft ferrite from 5 to 25 nm. We report a change in the regime of magnetic interaction between the layers from rigid-coupling to exchange-spring behavior, above a critical thickness of the soft magnetic Fe3O4 layer. We show that the symmetry and epitaxial matching between the spinel structures of CoFe2O4 and Fe3O4 at the interface stabilize the Verwey transition close to the bulk value even for 5-nm-thick Fe3O4 . The large interface exchange-coupling constant estimated from low-temperature M (H ) data confirmed the good quality of the ferrite-ferrite interface and the major role played by the interface in the magnetization dynamics. The results presented here constitute a model system for understanding the magnetic behavior of interfaces in core/shell nanoparticles and magnetic oxide-based spintronic devices.

  20. Microstructural investigation of magnetic CoFe2O4 nanowires inside carbon nanotubes by electron tomography.

    PubMed

    Ersen, Ovidiu; Bégin, Sylvie; Houllé, Matthieu; Amadou, Julien; Janowska, Izabela; Grenèche, Jean-Marc; Crucifix, Corinne; Pham-Huu, Cuong

    2008-04-01

    Magnetic nanowires of CoFe 2O4 were casted inside the channel of multiwall carbon nanotubes by mild chemical synthesis. A detailed investigation of these nanowires was performed using mainly the electron tomography technique; this study provides a complete characterization of their microstructure in terms of the spatial organization and the size distribution of individual particles forming the nanowire as well as its residual porosity. In particular, we have shown that the size of the CoFe 2O4 monocrystalline particles is closely dependent on the location of the particle within the nanotube, i.e., small particles close to the tube tip (5 nm) and bigger particles inside the tube channel (15 nm). As the theoretical critical size for superparamagnetic relaxation in CoFe 2O4 is estimated within the range of 4-9 nm, the size distribution obtained by 3D-TEM agrees with the Mossbauer study that suggests the presence of two different magnetic components inside the nanowire. We have shown also that, by using this preparation method and for this internal diameter of nanotube, the CoFe 2O4 nanowire exhibits a continuous structure along the tube, has a residual porosity of 38%, and can fill the tube at only 50%, parameters which influence in a significant manner the magnetic behavior of this system. PMID:18336009

  1. Toxicity of cobalt ferrite (CoFe2O4) nanobeads in Chlorella vulgaris: interaction, adaptation and oxidative stress.

    PubMed

    Ahmad, Farooq; Yao, Hongzhou; Zhou, Ying; Liu, Xiaoyi

    2015-11-01

    The potential toxicity of CoFe2O4 nanobeads (NBs) in Chlorella vulgaris was observed up to 72h. Algal cell morphology, membrane integrity and viability were severely compromised due to adsorption and aggregation of NBs on algal surfaces, release of Fe(3+) and Co(2+) ions and possible mechanical damage by NBs. Interactions with NBs and effective decrease in ions released by aggregation and exudation of algal cells as a self defense mechanism were observed by Fourier transform infrared attenuated total reflectance (FTIR-ATR) and inductively coupled plasma mass spectrometry (ICP-MS). The results corroborated CoFe2O4 NBs induced ROS triggered oxidative stress, leading to a reduction in catalase activity, activation of the mutagenic glutathione s-transferase (mu-GST) and acid phosphatase (AP) antioxidant enzymes, and an increase in genetic aberrations, metabolic and cellular signal transduction dysfunction. Circular dichroism (CD) spectra indicated the weak interactions of NBs with BSA, with slight changes in the α-helix structure of BSA confirming conformational changes in structure, hence the potential for functional interactions with biomolecules. Possible interferences of CoFe2O4 NBs with assay techniques and components indicated CoFe2O4 NBs at lower concentration do not show any significant interference with ROS, catalase, mu-GST and no interference with CD measurements. This study showed ROS production is one of the pathways of toxicity initiated by CoFe2O4 NBs and illustrates the complex processes that may occur between organisms and NBs in natural complex ecosystem.

  2. Dielectric response of epitaxially strained CoFe2O4 spinel thin films

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Diego; Foerster, Michael; Fina, Ignasi; Fontcuberta, Josep; Fritsch, Daniel; Ederer, Claude

    2012-09-01

    Aiming to explore strain effects on the dielectric permittivity of ultrathin films of oxides with spinel structure, we report here on the thickness (4-160 nm) dependence of the dielectric response of CoFe2O4 (CFO) epitaxial films grown on La2/3Sr1/3MnO3 buffered SrTiO3(001) substrates. It is found that films thicker than ˜30 nm display bulklike permittivity values (ɛr≈14); however, a pronounced and gradual ɛr reduction is observed for thinner films when the in-plane compressive strain induced by the substrate increases. First-principle calculations are used to simulate the variation of the permittivity of CFO spinel thin films under epitaxial strain; in agreement with simple bond-length considerations, the out-of-plane permittivity is predicted to increase under in-plane compressive strain due to the resulting out-of-plane lattice expansion, but this enhancement can be overcompensated if this expansion is suppressed, resulting in an effective reduction of permittivity. However, the predicted reduction is substantially smaller than observed experimentally. We discuss possible mechanisms to account for this observation.

  3. In situ chemical vapor deposition growth of carbon nanotubes on hollow CoFe2O4 as an efficient and low cost counter electrode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Yuan, Hong; Jiao, Qingze; Zhang, Shenli; Zhao, Yun; Wu, Qin; Li, Hansheng

    2016-09-01

    The composites of hollow CoFe2O4 and carbon nanotubes (h-CoFe2O4@CNTs) are successfully prepared by using a simple hydrothermal process coupling with the in-situ chemical vapor deposition (CVD) as electrocatalytic materials for counter electrode of dye-sensitized solar cells. The CNTs are uniformly grown on the surface of hollow CoFe2O4 particles verified by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) measurements. The electrochemical performances of hollow CoFe2O4@CNTs composites are evaluated by the EIS, Tafel polarization and CV measurements, and exhibiting high electrocatalytic performance for the reduction of triiodide. The presence of conductive polypyrrole nanoparticles could further improve the conductivity and catalytic performance of the resultant composites. Controlling the thickness of composites film, the optimum photovoltaic conversion efficiency of 6.55% is obtained, which is comparable to that of the cells fabricated with Pt counter electrode (6.61%). In addition, the composites exhibit a good long-term electrochemical stability in I3-/I- electrolyte.

  4. A facile hydrothermal synthesis, characterization and magnetic properties of mesoporous CoFe2O4 nanospheres

    NASA Astrophysics Data System (ADS)

    Reddy, M. Penchal; Mohamed, A. M. A.; Zhou, X. B.; Du, S.; Huang, Q.

    2015-08-01

    Mesoporous CoFe2O4 nanospheres with an average size of 180 nm were fabricated via a facile hydrothermal process using ethylene glycol as solvent and sodium acetate (NaAc) as electrostatic stabilizer. In this method, ethylene glycol plays a vital role in the formation of cobalt nanoospheres as a solvent and reducing agent. The structure and morphology of the prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The nanospheres exhibited ferromagnetic properties with high saturation magnetization value of about 60.19 emu/g at room temperature. The BET surface area of the nanospheres was determined using the nitrogen absorption method. The porous CoFe2O4 nanospheres displayed good magnetic properties, which may provide a very promising candidate for their applications in target drug delivery.

  5. Could microwave induced catalytic oxidation (MICO) process over CoFe2O4 effectively eliminate brilliant green in aqueous solution?

    PubMed

    Ju, Yongming; Wang, Xiaoyan; Qiao, Junqin; Li, Guohua; Wu, You; Li, Yuan; Zhang, Xiuyu; Xu, Zhencheng; Qi, Jianying; Fang, Jiande; Dionysiou, Dionysios D

    2013-12-15

    In this study, we adopted the chemical co-precipitation (CP) method and sol-gel method followed by calcination at temperatures of 100-900°C for 12h to synthesize CoFe2O4 materials, which were further characterized by TEM, XRD and XPS techniques. The properties of CoFe2O4 materials were evaluated in a microwave (MW) induced catalytic oxidation (MICO) process for the elimination of brilliant green (BG). The results showed that: (1) the removal rates of BG gradually decreased over a series of CoFe2O4 materials prepared by CP method and calcinated with 100-700°C (except 900°C) for 12h within three reuse cycles; for comparison, no removal of BG was obtained over CoFe2O4 synthesized by sol-gel method and CoFe2O4-900 (CP); (2) no hydroxyl radicals were captured with salicylic acid used as molecular probe in the MICO process; (3) MW irradiation enhanced the release of residual NaOH within the microstructure of CoFe2O4 and further discolored BG, because BG is sensitive to pH; (4) granular activated carbon (GAC), an excellent MW-absorbing material possessing higher dielectric loss tangent compared to that of a series of CoFe2O4 materials, could not remove BG in suspensions at a higher efficiency, even if the loading amount was 20 g L(-1). Accordingly, MICO process over CoFe2O4 materials and GAC could not effectively eliminate BG in suspensions. PMID:24220199

  6. Superior Electrochemical Properties of Nanofibers Composed of Hollow CoFe2 O4 Nanospheres Covered with Onion-Like Graphitic Carbon.

    PubMed

    Hong, Young Jun; Cho, Jung Sang; Kang, Yun Chan

    2015-12-01

    Nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon are prepared by applying nanoscale Kirkendall diffusion to the electrospinning process. Amorphous carbon nanofibers embedded with CoFe2 @onion-like carbon nanospheres are prepared by reduction of the electrospun nanofibers. Oxidation of the CoFe2 -C nanofibers at 300 °C under a normal atmosphere produces porous nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon. CoFe2 nanocrystals are transformed into the hollow CoFe2 O4 nanospheres during oxidation through a well-known nanoscale Kirkendall diffusion process. The discharge capacities of the carbon-free CoFe2 O4 nanofibers composed of hollow nanospheres and the nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon are 340 and 930 mA h g(-1) , respectively, for the 1000th cycle at a current density of 1 A g(-1) . The nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon exhibit an excellent rate performance even in the absence of conductive materials.

  7. Magnetic field dependence of piezoelectric resonance frequency in CoFe2O4-BaTiO3 composites

    NASA Astrophysics Data System (ADS)

    Kagomiya, Isao; Hayashi, Yusuke; Kakimoto, Ken-ichi; Kobayashi, Kazuyoshi

    2012-08-01

    The particulate and the multilayer CoFe2O4(CFO)-BaTiO3(BT) composites were prepared by the conventional solid state reaction method and the tape casting method, respectively. Both the prepared composites were simultaneously ferroelectric and ferromagnetic at room temperature. For the multilayer composite sample, a piezoelectric resonance frequency remarkably depended on the applied DC magnetic field, while no remarkable magnetic field dependence was observed for the particulate composite samples. An uniform magnetostriction of the CFO phase in the multilayer composite contributes to piezoelectric effect of the BT phases, resulting in the modulation of the piezoelectric resonance frequency.

  8. Directed self-assembly of epitaxial CoFe2O(4)-BiFeO3 multiferroic nanocomposites.

    PubMed

    Comes, Ryan; Liu, Hongxue; Khokhlov, Mikhail; Kasica, Richard; Lu, Jiwei; Wolf, Stuart A

    2012-05-01

    CoFe(2)O(4) (CFO)-BiFeO(3) (BFO) nanocomposites are an intriguing option for future memory and logic technologies due to the magnetoelectric properties of the system. However, these nanocomposites form with CFO pillars randomly located within a BFO matrix, making implementation in devices difficult. To overcome this, we present a technique to produce patterned nanocomposites through self-assembly. CFO islands are patterned on Nb-doped SrTiO(3) to direct the self-assembly of epitaxial CFO-BFO nanocomposites, producing square arrays of CFO pillars.

  9. Magnetic and magnetostrictive behavior of Dy 3+ doped CoFe 2O 4 single crystals grown by flux method

    NASA Astrophysics Data System (ADS)

    Kambale, Rahul C.; Song, K. M.; Won, C. J.; Lee, K. D.; Hur, N.

    2012-02-01

    We studied the effect of Dy 3+ content on the magnetic properties of cobalt ferrite single crystal. The single crystals of CoFe 1.9Dy 0.1O 4 were grown by the flux method using Na 2B 4O 7.10 H 2O (Borax) as a solvent (flux). The black and shiny single crystals were obtained as a product. The X-ray diffraction analysis at room temperature confirmed the spinel cubic structure with lattice constant a=8.42 Å of the single crystals. The compositional analysis endorses the presence of constituents Co, Fe and Dy elements after sintering at 1300 °C within the final structure. The magnetic hysteresis measurements at various temperatures viz. 10 K, 100 K, 200 K and 300 K reveal the soft ferrimagnetic nature of the single crystal than that of for pure CoFe 2O 4. The observed saturation magnetization ( Ms) and coercivity ( Hc) are found to be lower than that of pure CoFe 2O 4 single crystal. The magnetostriction ( λ) measurement was carried out along the [001] direction. The magnetic measurements lead to conclude that the present single crystals can be used for magneto-optic recording media.

  10. A novel method to fabricate CoFe2O4/SrFe12O19 composite ferrite nanofibers with enhanced exchange coupling effect

    NASA Astrophysics Data System (ADS)

    Pan, Lining; Cao, Derang; Jing, Panpan; Wang, Jianbo; Liu, Qingfang

    2015-03-01

    Nanocomposite of CoFe2O4/SrFe12O19 has been synthesized by the electrospinning and calcination process. A novel method that cobalt powder was used to replace traditional cobalt salt in the precursor sol-gel for electrospinning was proposed. The crystal structures, morphologies, and magnetic properties of these samples have been characterized in detail. Moreover, when the average crystallite size of the hard/soft phases reached up to an optimal value, the CoFe2O4 have an enhanced saturation magnetization of 62.8 emu/g and a coercivity of 2,290 Oe. Significantly, the hysteresis loops for the nanocomposites show a single-phase magnetization behavior, and it has been found that the exchange coupling interaction strongly exists in the CoFe2O4/SrFe12O19 magnetic nanocomposite nanofibers.

  11. A novel method to fabricate CoFe2O4/SrFe12O19 composite ferrite nanofibers with enhanced exchange coupling effect.

    PubMed

    Pan, Lining; Cao, Derang; Jing, Panpan; Wang, Jianbo; Liu, Qingfang

    2015-01-01

    Nanocomposite of CoFe2O4/SrFe12O19 has been synthesized by the electrospinning and calcination process. A novel method that cobalt powder was used to replace traditional cobalt salt in the precursor sol-gel for electrospinning was proposed. The crystal structures, morphologies, and magnetic properties of these samples have been characterized in detail. Moreover, when the average crystallite size of the hard/soft phases reached up to an optimal value, the CoFe2O4 have an enhanced saturation magnetization of 62.8 emu/g and a coercivity of 2,290 Oe. Significantly, the hysteresis loops for the nanocomposites show a single-phase magnetization behavior, and it has been found that the exchange coupling interaction strongly exists in the CoFe2O4/SrFe12O19 magnetic nanocomposite nanofibers. PMID:25852422

  12. Magnetic Properties of Liquid-Phase Sintered CoFe2O4 for Application in Magnetoelastic and Magnetoelectric Transducers

    PubMed Central

    de Brito, Vera Lúcia Othéro; Cunha, Stéphanie Alá; Lemos, Leonardo Violim; Nunes, Cristina Bormio

    2012-01-01

    Cobalt ferrite is a ferrimagnetic magnetostrictive ceramic that has potential application in magnetoelastic and magnetoelectric transducers. In this work, CoFe2O4 was obtained using a conventional ceramic method and Bi2O3 was used as additive in order to obtain liquid-phase sintered samples. Bi2O3 was added to the ferrite in amounts ranging from 0.25 mol% to 0.45 mol% and samples were sintered at 900 °C and 950 °C. It was observed the presence of Bi-containing particles in the microstructure of the sintered samples and the magnetostriction results indicated microstructural anisotropy. It was verified that it is possible to get dense cobalt ferrites, liquid-phase sintered, with relative densities higher than 90% and with magnetostriction values very close to samples sintered without additives. PMID:23112589

  13. Bistable Magnetoresistance Switching in Exchange-Coupled CoFe2O4-Fe3O4 Binary Nanocrystal Superlattices by Self-Assembly and Thermal Annealing

    SciTech Connect

    Chen, J; Ye, XC; Oh, SJ; Kikkawa, JM; Kagan, CR; Murray, CB

    2013-02-01

    Self-assembly of multicomponent nanocrystal superlattices provides a modular approach to the design of metamaterials by choosing constituent nanocrystal building blocks with desired physical properties and engineering the interparticle coupling. In this work, we report the self-assembly of binary nanocrystal superlattices composed of magnetically hard CoFe2O4 nanocrystals and magnetically soft Fe3O4 nanocrystals. Both NaZn13- and MgZn2-type CoFe2O4-Fe3O4 binary nanocrystal superlattices have been formed by the liquid-air interfacial assembly approach. Exchange coupling is achieved in both types of binary superlattices after thermal annealing under vacuum at 400 degrees C. The exchange-coupled CoFe2O4-Fe3O4 binary nanocrystal superlattices show single-phase magnetization switching behavior and magnetoresistance switching behavior below 200 K. The NaZn13-type CoFe2O4-Fe3O4 binary nanocrystal superlattices annealed at 500 degrees C even exhibit bistable magnetoresistance switching behavior at room temperature constituting a simple nonvolatile memory function.

  14. Comparative study of nano-sized particles CoFe2O4 effects on superconducting properties of Y-123 and Y-358

    NASA Astrophysics Data System (ADS)

    Slimani, Y.; Hannachi, E.; Ben Salem, M. K.; Hamrita, A.; Varilci, A.; Dachraoui, W.; Ben Salem, M.; Ben Azzouz, F.

    2014-10-01

    The effects of nano-sized CoFe2O4 particles (10 nm) addition on the structural and the normal state resistivity of YBa2Cu3O7 (noted Y-123) and Y3Ba5Cu8O18 (noted Y-358) polycrystalline were systematically studied. Samples were synthesized in oxygen atmosphere using a standard solid state reaction technique by adding CoFe2O4 up to 2 wt%. Phases, microstructure and superconductivity have been systematically investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrical measurements ρ(T). XRD results reveal that the lattice parameters change for both Y-123 and Y-358 phases. SEM observations reveal that the grain size is reduced with increasing the content of CoFe2O4. The measurements for the resistivity dependence of temperature show that the depression in superconducting temperature is more pronounced for CoFe2O4 addition in Y-358 compound than in Y-123 one. These results may be attributed to the existence of much more disorder due to a greater number of Cu sites to be substituted by Fe and Co in Y-358 compared to Y-123.

  15. Label-free electrochemical immunosensor based on enhanced signal amplification between Au@Pd and CoFe2O4/graphene nanohybrid

    PubMed Central

    Zhang, Yong; Li, Jiaojiao; Wang, Zhiling; Ma, Hongmin; Wu, Dan; Cheng, Qianhe; Wei, Qin

    2016-01-01

    The improvement of sensitivity of electrochemical immunosensor can be achieved via two approaches: increasing loading capacities of antibody and enlarging responding electrochemical signals. Based on these, CoFe2O4/graphene nanohybrid (CoFe2O4/rGO) as support was firstly used for preparing electrochemical biosensor, and with the addition of Au@Pd nanorods (NRs) as mimic enzyme, a label-free electrochemical immunosensor was prepared. Due to the high electrical conductivity, open porous structure and large loading capacities of CoFe2O4/rGO, the enhanced signal amplification between Au@Pd NRs and CoFe2O4/rGO was studied. Fabricated as a novel substrate, the prepared immunosensor had a good analytical performance and exhibited a wide linear range from 0.01 to 18.0 ng·mL−1 with a low detection limit of 3.3 pg·mL−1 for estradiol, which was succeeded in applying to detect estradiol in the natural water. PMID:26987503

  16. Synthesis and magnetic properties of hard magnetic (CoFe 2O 4)-soft magnetic (Fe 3O 4) nano-composite ceramics by SPS technology

    NASA Astrophysics Data System (ADS)

    Fei, Chunlong; Zhang, Yue; Yang, Zhi; Liu, Yong; Xiong, Rui; Shi, Jing; Ruan, Xuefeng

    2011-07-01

    CoFe2O4/Fe3O4 nano-composite ceramics were synthesized by Spark Plasma Sintering. The X-ray diffraction patterns show that all samples are composed of CoFe2O4 and Fe3O4 phases when the sintering temperature is below 900 °C. It is found that the magnetic properties strongly depend on the sintering temperature. The two-step hysteresis loops for samples sintered below 500 °C are observed, but when sintering temperature reaches 500 °C, the step disappears, which indicates that the CoFe2O4 and Fe3O4 are well exchange coupled. As the sintering temperature increases from 500 to 800 °C, the results of X-ray diffractometer indicate the constriction of crystalline regions due to the ion diffusion at the interfaces of CoFe2O4/Fe3O4 phases, which have great impact on the magnetic properties.

  17. Octadecylamine-Mediated Versatile Coating of CoFe2O4 NPs for the Sustained Release of Anti-Inflammatory Drug Naproxen and in Vivo Target Selectivity.

    PubMed

    Georgiadou, Violetta; Makris, George; Papagiannopoulou, Dionysia; Vourlias, Georgios; Dendrinou-Samara, Catherine

    2016-04-13

    Magnetic nanoparticles (MNPs) can play a distinct role in magnetic drug delivery via their distribution to the targeted area. The preparation of such MNPs is a challenging multiplex task that requires the optimization of size, magnetic, and surface properties for the achievement of desirable target selectivity, along with the sustained drug release as a prerequisite. In that context, CoFe2O4 MNPs with a small size of ∼7 nm and moderate saturation magnetization of ∼60 emu g(-1) were solvothermally synthesized in the presence of octadecylamine (ODA) with a view to investigate the functionalization route effect on the drug release. Synthetic regulations allowed us to prepare MNPs with aminated (AmMNPs) and amine-free (FAmMNPs) surface. The addition of the nonsteroidal anti-inflammatory drug with a carboxylate donor, Naproxen (NAP), was achieved by direct coupling with the NH2 groups, rendered by ODA, through the formation of an amide bond in the case of AmMNPs. In the case of FAmMNPs, indirect coupling of NAP was performed through an intermediate linker (polyethylenimine) and on PEG-ylated MNPs. FT-IR, (1)H NMR, (13)C NMR, and UV-vis data confirmed the addition of NAP, whereas diverse drug-release behavior was observed for the different functionalization approaches. The biological behavior of the MNPs@NAP was evaluated in vitro in rat serum and in vivo in mice, after radiolabeling with a γ-emitting radionuclide, (99m)Tc. The in vivo fate of MNPs@NAP carriers was in straightforward relation with the direct or indirect coupling of NAP. Furthermore, an inflammation was induced intramuscularly, where the directly coupled (99m)Tc-MNPs@NAP carriers showed increased accumulation at the inflammation site. PMID:26984632

  18. Strain-controlled easy axis orientation of epitaxial CoFe2O4 films by He implantation

    NASA Astrophysics Data System (ADS)

    Herklotz, Andreas; Wong, Antony T.; Rus, Stefania F.; Ward, Thomas Z.

    2015-03-01

    Heteroepitaxial strain engineering is an essential tool in the strongly correlated systems for investigating fundamental coupling effects and for more practical control of thin film properties. Here, we use strain doping by He implantation as an alternative technique to control thin film functionalities. We demonstrate the tuning of the magnetic anisotropy of CoFe2O4 (CFO) films through He implantation. Compressively strained thin films of CFO are grown coherently on MgO substrates and show pronounced out-of-plane magnetic anisotropy. Successive doping of the CFO films with He using a commercial ion gun results in an expansion of the out-of-plane lattice parameter while maintaining in-plane epitaxial lock to the substrate. We observe a continuous rotation of the magnetic easy axis towards the film plane with increasing unit cell tetragonality. The results are in agreement with the strain-induced change of the magnetic anisotropy due to the large negative magnetostriction of CFO and demonstrate that strain doping via He implantation is an elegant path to tune desired characteristics of transition metal oxide thin films. This work was supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division.

  19. Modification of structure and magnetic anisotropy of epitaxial CoFe2O4 films by hydrogen reduction

    NASA Astrophysics Data System (ADS)

    Chen, Aiping; Poudyal, Narayan; Xiong, Jie; Liu, J. Ping; Jia, Quanxi

    2015-03-01

    Heteroepitaxial CoFe2O4 (CFO) thin films with different thicknesses were deposited on MgO (001) substrates. The as-deposited CFO films show a clear switching of magnetic anisotropy with increasing film thickness. The thinner films (<100 nm) show a perpendicular magnetic anisotropy due to the out-of-plane compressive strain. The thicker films exhibit an in-plane easy axis owing to the dominating shape anisotropy effect. The magnetostriction coefficient of CFO films is estimated to be λ[001] = -188 × 10-6. Metallic CoFe2 films were obtained by annealing the as-deposited CFO films in forming gas (Ar 93% + H2 7%) at 450 °C. XRD shows that CoFe2 films are textured out-of-plane and aligned in-plane, owing to lattice matching between CoFe2 and MgO substrate. TEM results indicate that as-deposited films are continuous while the annealed films exhibit a nanopore mushroom structure. The magnetic anisotropy of CoFe2 films is dominated by the shape effect. The results demonstrate that hydrogen reduction can be effectively used to modify microstructures and physical properties of complex metal oxide materials.

  20. Exchange spring behaviour in SrFe12O19-CoFe2O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    Roy, Debangsu; Anil Kumar, P. S.

    2015-07-01

    Nanocomposites of hard (SrFe12O19) and soft ferrite (CoFe2O4) are prepared by mixing individual ferrite components at appropriate weight ratio and subsequent heat treatment. The magnetization of the composites showed hysteresis loop that is characteristic of the exchange spring system. The variation of Jr/Jr(∞) vs. Jd/ Jr(∞) for these nanocomposites are investigated to understand the presence of both the interacting field and the disorder in the system. This is further corroborated with the First Order Reversal Curve analysis (FORC) on the nanocomposites of 1:4 (Cobalt Ferrite: Strontium Ferrite) and 1:16 (Cobalt Ferrite: Strontium Ferrite). The FORC distribution reveals that the pinning mechanism is stronger in the nanocomposite of 1:4 compared to 1:16. However, the nanocomposite of 1:16 exhibit superior exchange coupling strength in contrast to 1:4. The asymmetric nature of the FORC distribution at Hc = 0 Oe for both the nanocomposites validates the intercoupling between the reversible and irreversible magnetization.

  1. Magnetoelectric coupling in multiferroic BaTiO3-CoFe2O4 composite nanofibers via electrospinning

    NASA Astrophysics Data System (ADS)

    Fu, Bi; Lu, Ruie; Gao, Kun; Yang, Yaodong; Wang, Yaping

    2015-07-01

    Magnetoelectric (ME) coupling in Pb-based multiferroic composites has been widely investigated due to the excellent piezoelectric property of lead zirconate titanate (PZT). In this letter, we report a strategy to create a hybrid Pb-free ferroelectric and ferromagnetic material and detect its ME coupling at the nanoscale. Hybrid Pb-free multiferroic BaTiO3-CoFe2O4 (BTO-CFO) composite nanofibers (NFs) were generated by sol-gel electrospinning. The perovskite structure of BTO and the spinel structure of CFO nanograins were homogenously distributed in the composite NFs and verified by bright-field transmission electron microscopy observations along the perovskite [111] zone axis. Multiferroicity was confirmed by amplitude-voltage butterfly curves and magnetic hysteresis loops. ME coupling was observed in terms of a singularity on a dM/dT curve at the ferroelectric Curie temperature (TC) of BaTiO3. The lateral ME coefficient was investigated by the evolution of the piezoresponse under an external magnetic field of 1000 Oe and was estimated to be α31 =0.78× 104 \\text{mV cm}-1 \\text{Oe}-1 . These findings could enable the creation of nanoscale Pb-free multiferroic composite devices.

  2. Development of novel exchange spring magnet by employing nanocomposites of CoFe2O4 and CoFe2

    NASA Astrophysics Data System (ADS)

    Safi, Rohollah; Ghasemi, Ali; Shoja-Razavi, Reza; Tavoosi, Majid

    2016-12-01

    CoFe2O4sbnd CoFe2 hard-soft nanocomposites were prepared via reduction of the cobalt ferrite CoFe2O4 in hydrogen atmosphere at different temperature. The structure and the room temperature magnetization of the samples were characterized by X-ray diffraction, field emission scanning electron microscope (FESEM) and vibrating sample magnetometer (VSM). It was found that the saturation magnetization of the nanocomposite powders increases by reduction temperature while their coercivity decreases. The highest Mr/Ms ratio of 0.52 was obtained for sample reduced at 550 °C. Single smooth hysteresis loops of nanocomposites show that these nanocomposites behave as the single-phase materials. This result indicates the presence of exchange coupling between two different hard and soft phases.

  3. Reusable nanocomposite of CoFe2O4/chitosan-graft-poly(acrylic acid) for removal of Ni(II) from aqueous solution

    NASA Astrophysics Data System (ADS)

    Nguyen, Van Cuong; Huynh, Thi Kim Ngoc

    2014-06-01

    In this paper, CoFe2O4/chitosan-graft-poly(acrylic acid) (CoFe2O4/CS-graft-PAA) nanocomposites were prepared successfully by coprecipitation of the compounds in alkaline solution and were used for removal of nickel (II) ions from aqueous solution. The sorption rate was affected significantly by the initial concentration of the solution, sorbent amount, and pH value of the solution. Batch experiments were conducted to investigate the adsorption capacity under different initial concentration (ranging from 25 to 150 mg L-1), solution pH (4.1, 5.3, 6.4 and 7.6), and contact time. These nanocomposites can be recycled conveniently from water with the assistance of an external magnet because of their exceptional properties. The prepared nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), x-ray powder diffraction (XRD), and thermogravimetric analysis (TGA).

  4. Fabrication of CoFe2O4-graphene nanocomposite and its application in the magnetic solid phase extraction of sulfonamides from milk samples.

    PubMed

    Li, Yazhen; Wu, Xuewen; Li, Zhaoqian; Zhong, Shuxian; Wang, Weiping; Wang, Aijun; Chen, Jianrong

    2015-11-01

    In the present study, a graphene-based magnetic nanocomposite (CoFe2O4-graphene, CoFe2O4-G) was synthesized and used successfully as an adsorbent for the magnetic solid phase extraction (MSPE) of sulfonamides for the first time. The surface morphologies and structures of the CoFe2O4-G nanocomposite were investigated by scanning electron microscopy (SEM), FT-IR, UV-vis spectroscopy, X-ray diffraction (XRD) and vibration sample magnetometer (VSM). Five sulfonamides, including sulfamerazine, sulfamethizole, sulfadoxine, sulfamethoxazole and sulfisoxazole were used as model analytes to evaluate the enrichment properties of the prepared adsorbent in MSPE. After preconcentration, the adsorbent could be conveniently separated from the aqueous samples by an external magnet, and the analytes desorbed from adsorbent were determined by high performance liquid chromatography-ultraviolet detection (HPLC-UV). Extraction parameters including sample pH, amount of sorbent, extraction time and desorption conditions were optimized in detail. Under the optimal conditions, good linear relationships between the peak areas and the concentrations of the analytes were obtained. The linear ranges were 0.02-50.00 mg L(-1) with correlation coefficients (r)≧0.9982. The limits of detection were less than 1.59 μg L(-1). Good reproducibility was obtained. The relative standard deviations of intra- and inter-day analysis were less than 4.3% and 6.5%, respectively. The proposed method was successfully applied for the analysis of sulfonamides in milk samples. The average recoveries determined for two milk samples spiked at levels from 5 to 20 μg L(-1) were 62.0-104.3% with relative standard deviations less than 14.0%. In addition, the CoFe2O4-G could be reused after cleaning with acetone and ultrapure water successively.

  5. CoFe 2O 4 spinel protection coating thermally converted from the electroplated Co-Fe alloy for solid oxide fuel cell interconnect application

    NASA Astrophysics Data System (ADS)

    Bi, Z. H.; Zhu, J. H.; Batey, J. L.

    CoFe 2O 4 has been demonstrated as a potential spinel coating for protecting the Cr-containing ferritic interconnects. This spinel had an electrical conductivity of 0.85 S cm -1 at 800 °C in air and an average coefficient of thermal expansion (CTE) of 11.80 × 10 -6 K -1 from room temperature to 800 °C. A series of Co-Fe alloys were co-deposited onto the Crofer 22 APU ferritic steel via electroplating with an acidic chloride solution. After thermal oxidation in air at 800 °C, a CoFe 2O 4 spinel layer was attained from the plated Co 0.40Fe 0.60 film. Furthermore, a channeled Crofer 22 APU interconnect electrodeposited with a 40-μm Co 0.40Fe 0.60 alloy film as a protective coating was evaluated in a single-cell configuration. The presence of the dense, Cr-free CoFe 2O 4 spinel layer was effective in blocking the Cr migration/transport and thus contributed to the improvement in cell performance stability.

  6. Magnetoelectric coupling effect in lead-free Bi4Ti3O12/CoFe2O4 composite films derived from chemistry solution deposition

    NASA Astrophysics Data System (ADS)

    Tang, Zhehong; Chen, Jieyu; Bai, Yulong; Zhao, Shifeng

    2016-08-01

    Lead-free magnetoelectric composite films combining Bi4Ti3O12 and CoFe2O4 were synthesized by chemical solution deposition on Pt (100)/Ti/SiO2/Si substrate. Morphological and electrical domain structure, ferroelectric, leakage, dielectric, piezoelectric, magnetic and magnetoelectric properties were investigated for Bi4Ti3O12/CoFe2O4 composite films. Well-defined interfaces between Bi4Ti3O12 and CoFe2O4 film layers and electrical domain structure were observed. The composite films show the coexistence of ferroelectric and ferromagnetic orders at room temperature. Larger piezoelectric coefficient and magnetization are obtained for the composite films, which is contributed to the magnetoelectric effect since it originates from the interface coupling through mechanical strain transfer. This work presents a feasible way to modulate the magnetoelectric coupling in ferromagnetic/ferroelectric composite films for developing lead-free micro-electro-mechanical system and information storage devices.

  7. Coin-like α-Fe2O3@CoFe2O4 core-shell composites with excellent electromagnetic absorption performance.

    PubMed

    Lv, Hualiang; Liang, Xiaohui; Cheng, Yan; Zhang, Haiqian; Tang, Dongming; Zhang, Baoshan; Ji, Guangbin; Du, Youwei

    2015-03-01

    In this paper, we designed a novel core-shell composite for microwave absorption application in which the α-Fe2O3 and the porous CoFe2O4 nanospheres served as the core and shell, respectively. Interestingly, during the solvothermal process, the solvent ratio (V) of PEG-200 to distilled water played a key role in the morphology of α-Fe2O3 for which irregular flake, coin-like, and thinner coin-like forms of α-Fe2O3 can be produced with the ratios of 1:7, 1:3, and 1:1, respectively. The porous 70 nm diameter CoFe2O4 nanospheres were generated as the shell of α-Fe2O3. It should be noted that the CoFe2O4 coating layer did not damage the original shape of α-Fe2O3. As compared with the uncoated α-Fe2O3, the Fe2O3@CoFe2O4 composites exhibited improved microwave absorption performance over the tested frequency range (2-18 GHz). In particular, the optimal reflection loss value of the flake-like composite can reach -60 dB at 16.5 GHz with a thin coating thickness of 2 mm. Furthermore, the frequency bandwidth corresponding to the RLmin value below -10 dB was up to 5 GHz (13-18 GHz). The enhanced microwave absorption properties of these composites may originate from the strong electron polarization effect (i.e., the electron polarization between Fe and Co) and the electromagnetic wave scattering on this special porous core-shell structure. In addition, the synergy effect between α-Fe2O3 and CoFe2O4 also favored balancing the electromagnetic parameters. Our results provided a promising approach for preparing an absorbent with good absorption intensity and a broad frequency that was lightweight.

  8. Monolithic integration of room-temperature multifunctional BaTiO3-CoFe2O4 epitaxial heterostructures on Si(001).

    PubMed

    Scigaj, Mateusz; Dix, Nico; Gázquez, Jaume; Varela, María; Fina, Ignasi; Domingo, Neus; Herranz, Gervasi; Skumryev, Vassil; Fontcuberta, Josep; Sánchez, Florencio

    2016-01-01

    The multifunctional (ferromagnetic and ferroelectric) response at room temperature that is elusive in single phase multiferroic materials can be achieved in a proper combination of ferroelectric perovskites and ferrimagnetic spinel oxides in horizontal heterostructures. In this work, lead-free CoFe2O4/BaTiO3 bilayers are integrated with Si(001) using LaNiO3/CeO2/YSZ as a tri-layer buffer. They present structural and functional properties close to those achieved on perovskite substrates: the bilayers are fully epitaxial with extremely flat surface, and exhibit robust ferromagnetism and ferroelectricity at room temperature. PMID:27550543

  9. Monolithic integration of room-temperature multifunctional BaTiO3-CoFe2O4 epitaxial heterostructures on Si(001)

    PubMed Central

    Scigaj, Mateusz; Dix, Nico; Gázquez, Jaume; Varela, María; Fina, Ignasi; Domingo, Neus; Herranz, Gervasi; Skumryev, Vassil; Fontcuberta, Josep; Sánchez, Florencio

    2016-01-01

    The multifunctional (ferromagnetic and ferroelectric) response at room temperature that is elusive in single phase multiferroic materials can be achieved in a proper combination of ferroelectric perovskites and ferrimagnetic spinel oxides in horizontal heterostructures. In this work, lead-free CoFe2O4/BaTiO3 bilayers are integrated with Si(001) using LaNiO3/CeO2/YSZ as a tri-layer buffer. They present structural and functional properties close to those achieved on perovskite substrates: the bilayers are fully epitaxial with extremely flat surface, and exhibit robust ferromagnetism and ferroelectricity at room temperature. PMID:27550543

  10. Monolithic integration of room-temperature multifunctional BaTiO3-CoFe2O4 epitaxial heterostructures on Si(001)

    NASA Astrophysics Data System (ADS)

    Scigaj, Mateusz; Dix, Nico; Gázquez, Jaume; Varela, María; Fina, Ignasi; Domingo, Neus; Herranz, Gervasi; Skumryev, Vassil; Fontcuberta, Josep; Sánchez, Florencio

    2016-08-01

    The multifunctional (ferromagnetic and ferroelectric) response at room temperature that is elusive in single phase multiferroic materials can be achieved in a proper combination of ferroelectric perovskites and ferrimagnetic spinel oxides in horizontal heterostructures. In this work, lead-free CoFe2O4/BaTiO3 bilayers are integrated with Si(001) using LaNiO3/CeO2/YSZ as a tri-layer buffer. They present structural and functional properties close to those achieved on perovskite substrates: the bilayers are fully epitaxial with extremely flat surface, and exhibit robust ferromagnetism and ferroelectricity at room temperature.

  11. On stoichiometry and intermixing at the spinel/perovskite interface in CoFe2O4/BaTiO3 thin films.

    PubMed

    Tileli, Vasiliki; Duchamp, Martial; Axelsson, Anna-Karin; Valant, Matjaz; Dunin-Borkowski, Rafal E; Alford, Neil McN

    2015-01-01

    The performance of complex oxide heterostructures depends primarily on the interfacial coupling of the two component structures. This interface character inherently varies with the synthesis method and conditions used since even small composition variations can alter the electronic, ferroelectric, or magnetic functional properties of the system. The focus of this article is placed on the interface character of a pulsed laser deposited CoFe2O4/BaTiO3 thin film. Using a range of state-of-the-art transmission electron microscopy methodologies, the roles of substrate morphology, interface stoichiometry, and cation intermixing are determined on the atomic level. The results reveal a surprisingly uneven BaTiO3 substrate surface formed after the film deposition and Fe atom incorporation in the top few monolayers inside the unit cell of the BaTiO3 crystal. Towards the CoFe2O4 side, a disordered region extending several nanometers from the interface was revealed and both Ba and Ti from the substrate were found to diffuse into the spinel layer. The analysis also shows that within this somehow incompatible composite interface, a different phase is formed corresponding to the compound Ba2Fe3Ti5O15, which belongs to the ilmenite crystal structure of FeTiO3 type. The results suggest a chemical activity between these two oxides, which could lead to the synthesis of complex engineered interfaces.

  12. On stoichiometry and intermixing at the spinel/perovskite interface in CoFe2O4/BaTiO3 thin films

    NASA Astrophysics Data System (ADS)

    Tileli, Vasiliki; Duchamp, Martial; Axelsson, Anna-Karin; Valant, Matjaz; Dunin-Borkowski, Rafal E.; Alford, Neil Mcn.

    2014-11-01

    The performance of complex oxide heterostructures depends primarily on the interfacial coupling of the two component structures. This interface character inherently varies with the synthesis method and conditions used since even small composition variations can alter the electronic, ferroelectric, or magnetic functional properties of the system. The focus of this article is placed on the interface character of a pulsed laser deposited CoFe2O4/BaTiO3 thin film. Using a range of state-of-the-art transmission electron microscopy methodologies, the roles of substrate morphology, interface stoichiometry, and cation intermixing are determined on the atomic level. The results reveal a surprisingly uneven BaTiO3 substrate surface formed after the film deposition and Fe atom incorporation in the top few monolayers inside the unit cell of the BaTiO3 crystal. Towards the CoFe2O4 side, a disordered region extending several nanometers from the interface was revealed and both Ba and Ti from the substrate were found to diffuse into the spinel layer. The analysis also shows that within this somehow incompatible composite interface, a different phase is formed corresponding to the compound Ba2Fe3Ti5O15, which belongs to the ilmenite crystal structure of FeTiO3 type. The results suggest a chemical activity between these two oxides, which could lead to the synthesis of complex engineered interfaces.The performance of complex oxide heterostructures depends primarily on the interfacial coupling of the two component structures. This interface character inherently varies with the synthesis method and conditions used since even small composition variations can alter the electronic, ferroelectric, or magnetic functional properties of the system. The focus of this article is placed on the interface character of a pulsed laser deposited CoFe2O4/BaTiO3 thin film. Using a range of state-of-the-art transmission electron microscopy methodologies, the roles of substrate morphology, interface stoichiometry, and cation intermixing are determined on the atomic level. The results reveal a surprisingly uneven BaTiO3 substrate surface formed after the film deposition and Fe atom incorporation in the top few monolayers inside the unit cell of the BaTiO3 crystal. Towards the CoFe2O4 side, a disordered region extending several nanometers from the interface was revealed and both Ba and Ti from the substrate were found to diffuse into the spinel layer. The analysis also shows that within this somehow incompatible composite interface, a different phase is formed corresponding to the compound Ba2Fe3Ti5O15, which belongs to the ilmenite crystal structure of FeTiO3 type. The results suggest a chemical activity between these two oxides, which could lead to the synthesis of complex engineered interfaces. Electronic supplementary information (ESI) available: Magnetic moment data of the structure, linear decomposition graph of the interface layer in its constituent components of CoFe2O4 and BaTiO3, reference Fe L3,2 EEL data used for MLLS analysis of the Fe oxidation and coordination variation, and a table detailing the partial ionization cross-sections used for quantitative MLLS analysis. See DOI: 10.1039/c4nr04339a

  13. Hyperfine interaction and tuning of magnetic anisotropy of Cu doped CoFe2O4 ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Batoo, Khalid Mujasam; Salah, Dina; Kumar, Gagan; Kumar, Arun; Singh, Mahavir; Abd El-sadek, M.; Mir, Feroz Ahmad; Imran, Ahamad; Jameel, Daler Adil

    2016-08-01

    Ferrimagnetic oxides may contain single or multi domain particles which get converted into superparamagnetic state near a critical size. To explore the existence of these particles, we have made Mössbauer and magnetic studies of Cu2+ substitution effect in CoFe2-xO4 Ferrites (0.0, 0.1, 0.2, 0.3, 0.4, and 0.5). All the samples have a cubic spinel structure with lattice parameters increasing linearly with increase in Cu content. The hysteresis loops yield a saturation magnetization, coercive field, and remanent magnetization that vary significantly with Cu content. The magnetic hysteresis curves shows a reduction in saturation magnetization and an increase in coercitivity with Cu2+ ion substitution. The anisotropy constant, K1, is found strongly dependent on the composition of Cu2+ ions. The variation of saturation magnetization with increasing Cu2+ ion content has been explained in the light of Neel's molecular field theory. Mössbauer spectra at room temperature shows two ferrimagnetically relaxed Zeeman sextets. The dependence of Mössbauer parameters such as isomer shift, quadrupole splitting, line width and hyperfine magnetic field on Cu2+ ion concentration have been discussed.

  14. Hierarchical templating of a BiFeO3-CoFe2O4 multiferroic nanocomposite by a triblock terpolymer film.

    PubMed

    Choi, Hong Kyoon; Aimon, Nicolas M; Kim, Dong Hun; Sun, Xue Yin; Gwyther, Jessica; Manners, Ian; Ross, Caroline A

    2014-09-23

    A process route to fabricate templated BiFeO3/CoFe2O4 (BFO/CFO) vertical nanocomposites is presented in which the self-assembly of the BFO/CFO is guided using a self-assembled triblock terpolymer. A linear triblock terpolymer was selected instead of a diblock copolymer in order to produce a square-symmetry template, which had a period of 44 nm. The triblock terpolymer pattern was transferred to a (001) Nb:SrTiO3 substrate to produce pits that formed preferential sites for the nucleation of CFO crystals, in contrast to the BFO, which wetted the flat regions of the substrate. The crystallographic orientation and magnetic properties of the templated BFO/CFO were characterized.

  15. Magnetic and thermoelectric properties of Fe3-xCoxO4 thin films and CoFe2O4/Fe3O4 superlattices

    NASA Astrophysics Data System (ADS)

    Nguyen van, Quang; Christian, Meny; Duong, Anh Tuan; Shin, Yooleemi; S. H, Rhim; Nguyen Thi, Minh Hai; Cho, Sunglae

    2015-03-01

    Microcrystalline ferrites are used as a medium for the magnetic recording and storage of information. Magnetite, Fe3O4, is a ferrimagnet with a cubic inverse spinel structure and exhibits a metal-insulator, Verwey, transition at about 120 K. It is predicted to possess as half-metallic nature, ~ 100% spin polarization, and high TC (850 K). Cobalt ferrite, Co3O4, is one of the most important members of the ferrite family, which is characterized by its high HC, moderate magnetization and very high magnetocrystalline anisotropy. Here we report on the magnetic and thermoelectric properties of Fe3-xCoxO4 (x = 0 to 1) thin films and CoFe2O4/Fe3O4 superlattices grown on MgO (100) by MBE. XRD and RHEED patterns confirmed the inverse spinel structure of the Fe3O4 films. Magnetic properties of the Fe3-xCoxO4 films are markedly sensitive to the Co content. The Verwey transition was disappeared in Co-doped films. A negative MR curve with butterfly shape was observed with low Co content but disappeared for the samples with x = 0.8 and 1. Seebeck coefficients increased with Co concentration; -70 μV/K for x =0 and -220 μV/K for x =1. We will also discuss on the relationship between magnetic and thermoelectric characteristics in CoFe2O4/Fe3O4 superlattices with the modulations of 5, 10, and 20 nm.

  16. Synthesis, characterization and Monte Carlo simulation of CoFe2O4/Polyvinylpyrrolidone nanocomposites: The coercivity investigation

    NASA Astrophysics Data System (ADS)

    Mirzaee, Sh; Farjami shayesteh, S.; Mahdavifar, S.; Hekmatara, S. Hoda.

    2015-11-01

    To study the influence of polymer matrix on the effective magnetic anisotropy constant and coercivity of magnetic nanoparticles, we have synthesized the Cobalt ferrite/Polyvinylpyrrolidone (PVP) nanocomposites by co-precipitation method in four different processes. In addition the Monte Carlo simulation and law of approach to the saturation magnetization have been applied to achieve the anisotropy constants. The obtained experimental and theoretical results showed a decrease in anisotropy constant relative to the bulk cobalt ferrite. We have showed that the PVP matrix can interact with metal cations and made them approximately immobilized to participate in spinel structure. Hence different anisotropy constants or coercivity were obtained for synthesized nanocomposites. In addition, PVP matrix can attach to the surface of magnetic particles and make them approximately non-interacting. The synthesized samples have been characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Magnetic measurements were made at room temperature using a vibrating sample magnetometer (VSM).

  17. Tuning the photovoltaic effect of multiferroic CoFe2O4/Pb(Zr, Ti)O3 composite films by magnetic fields

    NASA Astrophysics Data System (ADS)

    Pan, Dan-Feng; Chen, Guang-Yi; Bi, Gui-Feng; Zhang, Hao; Liu, Jun-Ming; Wang, Guang-Hou; Wan, Jian-Guo

    2016-05-01

    The 0-3 type CoFe2O4-Pb(Zr,Ti)O3 (CFO-PZT) multiferroic composite films have been prepared by a sol-gel process and spin-coating technique. A confirmable photovoltaic effect is observed under ultraviolet light irradiation. Moreover, this photovoltaic effect can be tuned by external magnetic fields. The maximum magnetic modulation ratios of short-circuit current density and open-circuit voltage can reach as high as 13.7% and 12.8% upon the application of 6 kOe DC magnetic field. Through remnant polarization measurements under various magnetic fields and detailed analysis of the energy band structures, we elucidate the mechanism of tuning photovoltaic effect by magnetic fields and attribute it to the combination of two factors. One is the decreased ferroelectric-polarization-induced depolarization electric field and another is the band structure reconstruction at CFO-PZT interfaces, both of which are dominated by the magnetoelectric coupling via interfacial stress transferring at nanoscale. This work makes some attempts of coupling photo-induced effects with magnetoelectric effect in multiferroic materials and will widen the practical ranges of multiferroic-based applications.

  18. Switching of magnetic easy-axis using crystal orientation for large perpendicular coercivity in CoFe2O4 thin film

    NASA Astrophysics Data System (ADS)

    Shirsath, Sagar E.; Liu, Xiaoxi; Yasukawa, Yukiko; Li, Sean; Morisako, Akimitsu

    2016-07-01

    Perpendicular magnetization and precise control over the magnetic easy axis in magnetic thin film is necessary for a variety of applications, particularly in magnetic recording media. A strong (111) orientation is successfully achieved in the CoFe2O4 (CFO) thin film at relatively low substrate temperature of 100 °C, whereas the (311)-preferred randomly oriented CFO is prepared at room temperature by the DC magnetron sputtering technique. The oxygen-deficient porous CFO film after post-annealing gives rise to compressive strain perpendicular to the film surface, which induces large perpendicular coercivity. We observe the coercivity of 11.3 kOe in the 40-nm CFO thin film, which is the highest perpendicular coercivity ever achieved on an amorphous SiO2/Si substrate. The present approach can guide the systematic tuning of the magnetic easy axis and coercivity in the desired direction with respect to crystal orientation in the nanoscale regime. Importantly, this can be achieved on virtually any type of substrate.

  19. Magnetoelectric Coupling in Well-Ordered Epitaxial BiFeO3/CoFe2O4/SrRuO3 Heterostructured Nanodot Array.

    PubMed

    Tian, Guo; Zhang, Fengyuan; Yao, Junxiang; Fan, Hua; Li, Peilian; Li, Zhongwen; Song, Xiao; Zhang, Xiaoyan; Qin, Minghui; Zeng, Min; Zhang, Zhang; Yao, Jianjun; Gao, Xingsen; Liu, Junming

    2016-01-26

    Multiferroic magnetoelectric (ME) composites exhibit sizable ME coupling at room temperature, promising applications in a wide range of novel devices. For high density integrated devices, it is indispensable to achieve a well-ordered nanostructured array with reasonable ME coupling. For this purpose, we explored the well-ordered array of isolated epitaxial BiFeO3/CoFe2O4/SrRuO3 heterostructured nanodots fabricated by nanoporous anodic alumina (AAO) template method. The arrayed heterostructured nanodots demonstrate well-established epitaxial structures and coexistence of piezoelectric and ferromagnetic properties, as revealed by transmission electron microscopy (TEM) and peizoeresponse/magnetic force microscopy (PFM/MFM). It was found that the heterostructured nanodots yield apparent ME coupling, likely due to the effective transfer of interface couplings along with the substantial release of substrate clamping. A noticeable change in piezoelectric response of the nanodots can be triggered by magnetic field, indicating a substantial enhancement of ME coupling. Moreover, an electric field induced magnetization switching in these nanodots can be observed, showing a large reverse ME effect. These results offer good opportunities of the nanodots for applications in high-density ME devices, e.g., high density recording (>100 Gbit/in.(2)) or logic devices. PMID:26651132

  20. Switching of magnetic easy-axis using crystal orientation for large perpendicular coercivity in CoFe2O4 thin film

    PubMed Central

    Shirsath, Sagar E.; Liu, Xiaoxi; Yasukawa, Yukiko; Li, Sean; Morisako, Akimitsu

    2016-01-01

    Perpendicular magnetization and precise control over the magnetic easy axis in magnetic thin film is necessary for a variety of applications, particularly in magnetic recording media. A strong (111) orientation is successfully achieved in the CoFe2O4 (CFO) thin film at relatively low substrate temperature of 100 °C, whereas the (311)-preferred randomly oriented CFO is prepared at room temperature by the DC magnetron sputtering technique. The oxygen-deficient porous CFO film after post-annealing gives rise to compressive strain perpendicular to the film surface, which induces large perpendicular coercivity. We observe the coercivity of 11.3 kOe in the 40-nm CFO thin film, which is the highest perpendicular coercivity ever achieved on an amorphous SiO2/Si substrate. The present approach can guide the systematic tuning of the magnetic easy axis and coercivity in the desired direction with respect to crystal orientation in the nanoscale regime. Importantly, this can be achieved on virtually any type of substrate. PMID:27435010

  1. Evidence on the presence of Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in CoFe2O4@Au nano structure

    NASA Astrophysics Data System (ADS)

    El-Sayed, H. M.

    2016-03-01

    In this work, a straight forward method for preparing CoFe2O4/Au core shell nano composite is introduced. By this method, samples with different thickness of Au as shell were obtained. The crystal and micro structures of the prepared samples were studied using x-ray diffraction and TEM micrographs. The presence of plasmonic frequencies of gold nano particles was investigated by measuring absorbance spectra in the visible range. It was found that, the plasma frequency decreases with increasing the gold thickness. The effect of the gold thickness on the magnetization, nucleation field and magnetic loss were studied. The experimental measurements showed an oscillating behavior of the magnetic parameters with increasing gold thickness. These results could be explained in terms of the presence of Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between the ferromagnetic components via the conduction electrons of the gold metal. The heating ability of the magnetic Co-Ferrite particles under high frequency magnetic field was enhanced by the presence of the gold as a shell.

  2. Enhanced electrocatalytic activity of PANI and CoFe2O4/PANI composite supported on graphene for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Mohanraju, Karuppannan; Sreejith, Vasudevan; Ananth, Ramaiyan; Cindrella, Louis

    2015-06-01

    New catalysts of reduced graphene oxide (rGO) with poly aniline (PANI) and cobalt ferrite (CF) have been successfully prepared by simple chemical reduction method. Their electrocatalytic activity for oxygen reduction reaction (ORR) was evaluated. Semi-crystalline nature of CF was analyzed by X-ray diffraction (XRD) study. Surface morphology by HR-SEM showed features of CF particles and PANI film on graphene sheets. FT-IR studies revealed changes in C-N and Cdbnd N stretching vibrations of PANI confirming bonding of PANI to graphene sheets. Raman spectrum showed presence of PANI on distorted graphene layers. TG/DTA revealed thermal stability and extent of loading of CF in composite. ORR performance was studied using catalyst modified rotating disc electrode (RDE). A maximum kinetic current density of -3.46 mA cm-2 at -0.2 V was obtained for CF/PANI/rGO. Tafel slope, onset and half wave potentials for the catalyst were obtained from ORR response. Durability studies showed that synthesized electrocatalyst has better stability and methanol tolerance than commercial Pt/C catalyst. To the best of our knowledge, this is the first study aiming enhancement of ORR activity using PANI and CoFe2O4 on graphene support. A trace amount of Pt in the composite boosted the performance of single PEM fuel cell.

  3. Ligand-induced evolution of intrinsic fluorescence and catalytic activity from cobalt ferrite nanoparticles.

    PubMed

    Pal, Monalisa; Kundu, Anirban; Rakshit, Rupali; Mandal, Kalyan

    2015-06-01

    To develop CoFe(2)O(4) as magneto-fluorescent nanoparticles (NPs) for biomedical applications, it would be advantageous to identify any intrinsic fluorescence of this important magnetic material by simply adjusting the surface chemistry of the NPs themselves. Herein, we demonstrate that intrinsic multicolor fluorescence, covering the whole visible region, can be induced by facile functionalization of CoFe(2)O(4) NPs with Na-tartrate. Moreover, the functionalized CoFe(2)O(4) NPs also show unprecedented catalytic efficiency in the degradation of both biologically and environmentally harmful dyes, pioneering the potential application of these NPs in therapeutics and wastewater treatment. Detailed investigation through various spectroscopic tools unveils the story behind the emergence of this unique optical property of CoFe(2)O(4) NPs upon functionalization with tartrate ligands. We believe our developed multifunctional CoFe(2)O(4) NPs hold great promise for advanced biomedical and technological applications. PMID:25867626

  4. Ligand-induced evolution of intrinsic fluorescence and catalytic activity from cobalt ferrite nanoparticles.

    PubMed

    Pal, Monalisa; Kundu, Anirban; Rakshit, Rupali; Mandal, Kalyan

    2015-06-01

    To develop CoFe(2)O(4) as magneto-fluorescent nanoparticles (NPs) for biomedical applications, it would be advantageous to identify any intrinsic fluorescence of this important magnetic material by simply adjusting the surface chemistry of the NPs themselves. Herein, we demonstrate that intrinsic multicolor fluorescence, covering the whole visible region, can be induced by facile functionalization of CoFe(2)O(4) NPs with Na-tartrate. Moreover, the functionalized CoFe(2)O(4) NPs also show unprecedented catalytic efficiency in the degradation of both biologically and environmentally harmful dyes, pioneering the potential application of these NPs in therapeutics and wastewater treatment. Detailed investigation through various spectroscopic tools unveils the story behind the emergence of this unique optical property of CoFe(2)O(4) NPs upon functionalization with tartrate ligands. We believe our developed multifunctional CoFe(2)O(4) NPs hold great promise for advanced biomedical and technological applications.

  5. Investigation on multiferroic, optical and photoluminescence properties of CoFe2O4/(Pb1-xSrx)TiO3 nanostructured composite thin films

    NASA Astrophysics Data System (ADS)

    Bala, Kanchan; Sharma, Pankaj; Negi, N. S.

    2016-11-01

    Multiferroic nanostructured composite thin films consisting of CoFe2O4 (CFO) and Pb1-xSrxTiO3 (PST; x = 0.1, 0.2, 0.3, 0.4 and 0.5) layers have been deposited on Pt/TiO2/SiO2/Si and quartz substrates by using metallo-organic decomposition process and spin coating. The effect of Sr content on the multiferroic and optical properties have been investigated. The phase purity such as spinel structure of CFO and perovskite structure of PST has been verified by X-ray diffraction. Cross-sectional scanning electron microscopy images revealed clear interface between CFO and PST layers without any noticeable diffusion. The multiferroic properties of CFO/PST composite films have been confirmed by magnetic and ferroelectric hysteresis loops with low leakage current density. The residual strain sensitivity of multiferroic and optical properties has been observed in the composite films. The decrease in saturation magnetization and saturation polarization with increase in Sr content has been observed which could be attributed to the decrease in residual strain of CFO/PST composite films. The magnetic phase transition temperature of the CFO/PST composite films is also reduced. The optical refractive index decreases with increase of amount of Sr content. The photoluminescence spectra of the CFO/PST composite films possess a blue shift which can be attributed to the Pb and oxygen vacancies as localized sensitizing centers. We show that the multiferroic and optical properties of the CFO/PST composite films are highly sensitive to the heterostructure strains which can be controlled by Sr content.

  6. Preparation of silica coated cobalt ferrite magnetic nanoparticles for the purification of histidine-tagged proteins

    NASA Astrophysics Data System (ADS)

    Aygar, Gülfem; Kaya, Murat; Özkan, Necati; Kocabıyık, Semra; Volkan, Mürvet

    2015-12-01

    Surface modified cobalt ferrite (CoFe2O4) nanoparticles containing Ni-NTA affinity group were synthesized and used for the separation of histidine tag proteins from the complex matrices through the use of imidazole side chains of histidine molecules. Firstly, CoFe2O4 nanoparticles with a narrow size distribution were prepared in an aqueous solution using the controlled co-precipitation method. In order to obtain small CoFe2O4 agglomerates, oleic acid and sodium chloride were used as dispersants. The CoFe2O4 particles were coated with silica and subsequently the surface of these silica coated particles (SiO2-CoFe2O4) was modified by amine (NH2) groups in order to add further functional groups on the silica shell. Then, carboxyl (-COOH) functional groups were added to the SiO2-CoFe2O4 magnetic nanoparticles through the NH2 groups. After that Nα,Nα-Bis(carboxymethyl)-L-lysine hydrate (NTA) was attached to carboxyl ends of the structure. Finally, the surface modified nanoparticles were labeled with nickel (Ni) (II) ions. Furthermore, the modified SiO2-CoFe2O4 magnetic nanoparticles were utilized as a new system that allows purification of the N-terminal His-tagged recombinant small heat shock protein, Tpv-sHSP 14.3.

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

    PubMed

    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

    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

  8. Strong magnetoelectric coupling in sol-gel derived multiferroic (Pb0.76Ca0.24)TiO3-CoFe2O4 composite films

    NASA Astrophysics Data System (ADS)

    Cheng, T. D.; Tang, X. G.; Wang, Yu; Chan, H. L. W.

    2012-10-01

    A multilayer heterostructure composite thin films consisting of alternating layers (Pb0.76Ca0.24)TiO3 (PCT) and CoFe2O4 (CFO) were grown on Pt/Ti/SiO2/Si(100) substrate by a sol-gel process. X-ray measurements indicated high quality of crystallization of both PCT and CFO layers. The magnetic and ferroelectric properties of the composite were investigated. Well-defined polarization vs. electric field (P-E) and magnetic hysteresis (M-H) loops were obtained. A strong magnetoelectric (ME) response was observed in the sample which was subjected to an alternating magnetic field, and a high ME voltage coefficient αE = 870 mV/Oe cm was obtained for the composite thin films when applied magnetic field parallel to the sample plane.

  9. Multiferroic and magnetoelectric properties of Ba0.85Ca0.15Zr0.1Ti0.9O3-CoFe2O4 core-shell nanocomposite

    NASA Astrophysics Data System (ADS)

    Kumar, Ajith S.; Lekha, C. S. Chitra; Vivek, S.; Saravanan, Venkata; Nandakumar, K.; Nair, Swapna S.

    2016-11-01

    Lead-free magnetoelectric (ME) composites with remarkable ME coupling are required for the realization of eco-friendly multifunctional devices. This work demonstrates the ME properties of Ba0.85Ca0.15Zr0.1Ti0.9O3-CoFe2O4 (BCZT-CFO) core-shell composites synthesized via co-sol-gel technique. Room temperature ferroelectric and ferromagnetic characterization have shown that the samples are magnetic and ferroelectric along with an adequate magnetoelectric coupling of 12.15 mV/(cm Oe). The strong dependence of electric parameters on applied magnetic DC bias fields demonstrated in ferroelectric and magnetoelectric measurements provide a framework for the development of potential magnetoelectric devices. Also, the high sensitivity of magnetoelectric coupling towards the applied AC magnetic field can be used for its application in magnetoelectric sensors.

  10. Structural and morphological studies of manganese substituted CoFe2O4 and NiFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Ranjith kumar, E.; Jayaprakash, R.; Patel, Rajesh

    2013-10-01

    Nanocrystalline manganese substituted cobalt and nickel ferrites have been synthesized through the evaporation method by using egg white. These powders were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The XRD pattern of manganese substituted spinel ferrites contains some impurity peaks, which are the decomposition of the ferrites to α-Fe2O3 phase at higher annealing temperature. The microstructure and particle size of the annealed sample analyzed by TEM, which gives the particle size well with XRD. The magnetic properties were measured using Vibrating Sample Magnetometer (VSM). The surface/near-surface chemical states of the nanocrystalline manganese substituted cobalt and nickel ferrites are analyzed by XPS within a range of binding energies of 0-1000 eV.

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

    PubMed Central

    Drašler, Barbara; Drobne, Damjana; Novak, Sara; Valant, Janez; Boljte, Sabina; Otrin, Lado; Rappolt, Michael; Sartori, Barbara; Iglič, Aleš; Kralj-Iglič, Veronika; Šuštar, Vid; Makovec, Darko; Gyergyek, Sašo; Hočevar, Matej; Godec, Matjaž; Zupanc, Jernej

    2014-01-01

    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. PMID:24741305

  12. Synthesis of Monodisperse FeCo Nanoparticles by Reductive Salt-Matrix Annealing

    SciTech Connect

    Poudyal, Narayan; Chaubey, Girija S.; Rong, Chuan-bing; Cui, Jun; Liu, J.Ping

    2013-08-02

    We report here a novel synthetic method to prepare monodisperse air-stable FeCo nanoparticles. CoFe2O4 nanoparticles with different sizes were first synthesized by a chemical solution method. The as-synthesized CoFe2O4 nanoparticles were then mixed with ball-milled NaCl powders and heated to 400–500oC in forming gas (Ar 93% + H2 7%). The salt powder worked as a separating medium that prevents the CoFe2O4 nanoparticles from agglomerating during the heat treatment while the forming gas reduces the CoFe2O4 nanoparticles to FeCo nanoparticles. Monodisperse FeCo nanoparticles were recovered by dissolving the NaCl in water and subsequently washing with ethanol and acetone. Structural analyses confirmed that FeCo nanoparticles retained the same size as their oxide precursors. The size of the FeCo nanoparticles can be well tuned by controlling the size of the CoFe2O4 nanoparticles. The saturation magnetization of FeCo nanoparticles is size dependent and increases with size.

  13. Strain and Ferroelectric-Field Effects Co-mediated Magnetism in (011)-CoFe2O4/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 Multiferroic Heterostructures.

    PubMed

    Wang, Ping; Jin, Chao; Zheng, Dongxing; Li, Dong; Gong, Junlu; Li, Peng; Bai, Haili

    2016-09-14

    Electric-field mediated magnetism was investigated in CoFe2O4 (CFO, deposited by reactive cosputtering under different oxygen flow rates) films fabricated on (011)-Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) substrates. Ascribed to the volatile strain effect of PMN-PT, the magnetization of the CFO films decreases along the [01-1] direction whereas it increases along the [100] direction under the electric field, which is attributed to the octahedron distortion in the spinel ferrite. Moreover, a nonvolatile mediation was obtained in the CFO film with low oxygen flow rate (4 sccm), deriving from the ferroelectric-field effect, in which the magnetization is different after removing the positive and negative fields. The cooperation of the two effects produces four different magnetization states in the CFO film with low oxygen flow rate (4 sccm), compared to the only two different states in the CFO film with high oxygen flow rate (10 sccm). It is suggested that the ferroelectric-field effect is related to the oxygen vacancies in CFO films. PMID:27540866

  14. Strain and Ferroelectric-Field Effects Co-mediated Magnetism in (011)-CoFe2O4/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 Multiferroic Heterostructures.

    PubMed

    Wang, Ping; Jin, Chao; Zheng, Dongxing; Li, Dong; Gong, Junlu; Li, Peng; Bai, Haili

    2016-09-14

    Electric-field mediated magnetism was investigated in CoFe2O4 (CFO, deposited by reactive cosputtering under different oxygen flow rates) films fabricated on (011)-Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) substrates. Ascribed to the volatile strain effect of PMN-PT, the magnetization of the CFO films decreases along the [01-1] direction whereas it increases along the [100] direction under the electric field, which is attributed to the octahedron distortion in the spinel ferrite. Moreover, a nonvolatile mediation was obtained in the CFO film with low oxygen flow rate (4 sccm), deriving from the ferroelectric-field effect, in which the magnetization is different after removing the positive and negative fields. The cooperation of the two effects produces four different magnetization states in the CFO film with low oxygen flow rate (4 sccm), compared to the only two different states in the CFO film with high oxygen flow rate (10 sccm). It is suggested that the ferroelectric-field effect is related to the oxygen vacancies in CFO films.

  15. Ultrasmall inorganic nanoparticles: State-of-the-art and perspectives for biomedical applications.

    PubMed

    Zarschler, Kristof; Rocks, Louise; Licciardello, Nadia; Boselli, Luca; Polo, Ester; Garcia, Karina Pombo; De Cola, Luisa; Stephan, Holger; Dawson, Kenneth A

    2016-08-01

    Ultrasmall nanoparticulate materials with core sizes in the 1-3nm range bridge the gap between single molecules and classical, larger-sized nanomaterials, not only in terms of spatial dimension, but also as regards physicochemical and pharmacokinetic properties. Due to these unique properties, ultrasmall nanoparticles appear to be promising materials for nanomedicinal applications. This review overviews the different synthetic methods of inorganic ultrasmall nanoparticles as well as their properties, characterization, surface modification and toxicity. We moreover summarize the current state of knowledge regarding pharmacokinetics, biodistribution and targeting of nanoscale materials. Aside from addressing the issue of biomolecular corona formation and elaborating on the interactions of ultrasmall nanoparticles with individual cells, we discuss the potential diagnostic, therapeutic and theranostic applications of ultrasmall nanoparticles in the emerging field of nanomedicine in the final part of this review.

  16. Ultrasmall inorganic nanoparticles: State-of-the-art and perspectives for biomedical applications.

    PubMed

    Zarschler, Kristof; Rocks, Louise; Licciardello, Nadia; Boselli, Luca; Polo, Ester; Garcia, Karina Pombo; De Cola, Luisa; Stephan, Holger; Dawson, Kenneth A

    2016-08-01

    Ultrasmall nanoparticulate materials with core sizes in the 1-3nm range bridge the gap between single molecules and classical, larger-sized nanomaterials, not only in terms of spatial dimension, but also as regards physicochemical and pharmacokinetic properties. Due to these unique properties, ultrasmall nanoparticles appear to be promising materials for nanomedicinal applications. This review overviews the different synthetic methods of inorganic ultrasmall nanoparticles as well as their properties, characterization, surface modification and toxicity. We moreover summarize the current state of knowledge regarding pharmacokinetics, biodistribution and targeting of nanoscale materials. Aside from addressing the issue of biomolecular corona formation and elaborating on the interactions of ultrasmall nanoparticles with individual cells, we discuss the potential diagnostic, therapeutic and theranostic applications of ultrasmall nanoparticles in the emerging field of nanomedicine in the final part of this review. PMID:27013135

  17. Magnetoelectric coupling in lead-free piezoelectric Lix(K0.5Na0.5)1 - xNb1 - yTayO3 and magnetostrictive CoFe2O4 laminated composites

    NASA Astrophysics Data System (ADS)

    Fu, Jiyong; Santa Rosa, Washington; M'Peko, Jean Claude; Algueró, Miguel; Venet, Michel

    2016-04-01

    To replace lead zirconium titanate in magnetoelectric (ME) composites owing to concerns regarding its toxicity, we investigate the ME coupling in bilayer composites comprising lead-free Lix(K0.5Na0.5)1 - xNb1 - yTayO3 (LKNNT) (piezoelectric) and CoFe2O4 (magnetostrictive) phases. We prepare the LKNNT ceramics and measure its piezoelectric coefficient d31, a crucial ingredient determining ME couplings, for several Li (x = 0.03 , 0.035 , 0.04) and Ta (y = 0.15 , 0.2 , 0.25) concentrations, and find that the highest d31 occurs at y = 0.2 for all the values of x studied here. We then evaluate both the transverse (αE,31) and the longitudinal (αE,33) low-frequency ME coupling coefficients of our composites, for each the above composition of (x , y). At x = 0.03, we find the usual scenario of αE,31 and αE,33, i.e., the strongest ME coupling occurs when d31 is maximal, namely at y = 0.2. On the other hand, interestingly, we also obtain the strongest ME coupling when the LKNNT layer has a relatively weaker d31, e.g., at y = 0.25 for x = 0.035 and y = 0.15 for x = 0.04, following from the interplay of d31 and other ingredients (e.g., dielectric constant). Our calculated ME couplings, with αE,31 in magnitude around twice of αE,33, are comparable to those in lead-based composites. The effect of the volume fraction and interface parameter on the ME coupling is also discussed.

  18. Ultrasmall lanthanide-doped nanoparticles as multimodal platforms

    NASA Astrophysics Data System (ADS)

    Yust, Brian G.; Pedraza, Francisco J.; Sardar, Dhiraj K.

    2014-03-01

    Recently, there has been a great amount of interest in nanoparticles which are able to provide a platform with high contrast for multiple imaging modalities in order to advance the tools available to biomedical researchers and physicians. However, many nanoparticles do not have ideal properties to provide high contrast in different imaging modes. In order to address this, ultrasmall lanthanide doped oxide and fluoride nanoparticles with strong NIR to NIR upconversion fluorescence and a strong magnetic response for magnetic resonance imaging (MRI) have been developed. Specifically, these nanoparticles incorporate gadolinium, dysprosium, or a combination of both into the nano-crystalline host to achieve the magnetic properties. Thulium, erbium, and neodymium codopants provide the strong NIR absorption and emission lines that allow for deeper tissue imaging since near infrared light is not strongly absorbed or scattered by most tissues within this region. This also leads to better image quality and lower necessary excitation intensities. As a part of the one pot synthesis, these nanoparticles are coated with peg, pmao, or d-glucuronic acid to make them water soluble, biocompatible, and bioconjugable due to the available carboxyl or amine groups. Here, the synthesis, morphological characterization, magnetic response, NIR emission, and the quantum yield will be discussed. Cytotoxicity tested through cell viability at varying concentrations of nanoparticles in growth media will also be discussed.

  19. Molecularly stabilised ultrasmall gold nanoparticles: synthesis, characterization and bioactivity

    NASA Astrophysics Data System (ADS)

    Leifert, Annika; Pan-Bartnek, Yu; Simon, Ulrich; Jahnen-Dechent, Willi

    2013-06-01

    Gold nanoparticles (AuNPs) are widely used as contrast agents in electron microscopy as well as for diagnostic tests. Due to their unique optical and electrical properties and their small size, there is also a growing field of potential applications in medical fields of imaging and therapy, for example as drug carriers or as active compounds in thermotherapy. Besides their intrinsic optical properties, facile surface decoration with (bio)functional ligands renders AuNPs ideally suited for many industrial and medical applications. However, novel AuNPs may have toxicological profiles differing from bulk and therefore a thorough analysis of the quantitative structure-activity relationship (QSAR) is required. Several mechanisms are proposed that cause adverse effects of nanoparticles in biological systems. Catalytic generation of reactive species due to the large and chemically active surface area of nanomaterials is well established. Because nanoparticles approach the size of biological molecules and subcellular structures, they may overcome natural barriers by active or passive uptake. Ultrasmall AuNPs with sizes of 2 nm or less may even behave as molecular ligands. These types of potential interactions would imply a size and ligand-dependent behaviour of any nanomaterial towards biological systems. Thus, to fully understand their QSAR, AuNPs bioactivity should be analysed in biological systems of increasing complexity ranging from cell culture to whole animal studies.

  20. Synthesis and properties MFe2O4 (M = Fe, Co) nanoparticles and core-shell structures

    NASA Astrophysics Data System (ADS)

    Yelenich, O. V.; Solopan, S. O.; Greneche, J. M.; Belous, A. G.

    2015-08-01

    Individual Fe3-xO4 and CoFe2O4 nanoparticles, as well as Fe3-xO4/CoFe2O4 core/shell structures were synthesized by the method of co-precipitation from diethylene glycol solutions. Core/shell structure were synthesized with CoFe2O4-shell thickness of 1.0, 2.5 and 3.5 nm. X-ray diffraction patterns of individual nanoparticles and core/shell are similar and indicate that all synthesized samples have a cubic spinel structure. Compares Mössbauer studies of CoFe2O4, Fe3-xO4 nanoparticles indicate superparamagnetic properties at 300 K. It was shown that individual magnetite nanoparticles are transformed into maghemite through oxidation during the synthesis procedure, wherein the smallest nanoparticles are completely oxidized while a magnetite core does occur in the case of the largest nanoparticles. The Mössbauer spectra of core/shell nanoparticles with increasing CoFe2O4-shell thickness show a gradual decrease in the relative intensity of the quadrupole doublet and significant decrease of the mean isomer shift value at both RT and 77 K indicating a decrease of the superparamagnetic relaxation phenomena. Specific loss power for the prepared ferrofluids was experimentally calculated and it was determined that under influence of ac-magnetic field magnetic fluid based on individual CoFe2O4 and Fe3-xO4 particles are characterized by very low heating temperature, when magnetic fluids based on core/shell nanoparticles demonstrate higher heating effect.

  1. On Ultrasmall Nanocrystals

    PubMed Central

    McBride, James R.; Dukes, Albert D.; Schreuder, Michael A.; Rosenthal, Sandra J.

    2010-01-01

    Ultrasmall nanocrystals are a growing sub-class of traditional nanocrystals that exhibit new properties at diameters typically below 2 nm. In this review, we define what constitutes an ultrasmall nanoparticle while distinguishing between ultrasmall and magic-size nanoparticles. After a brief overview of ultrasmall nanoparticles, including ultrasmall gold clusters, our recent work is presented covering the optical properties, structure, and application of ultrasmall CdSe nanocrystals. This unique material has potential application in solid state lighting due to its balanced white emission. This section is followed by a discussion on the blurring boundary between what can be considered a nanoparticle and a molecule. PMID:21132106

  2. Biointeractions of ultrasmall glutathione-coated gold nanoparticles: effect of small size variations

    NASA Astrophysics Data System (ADS)

    Sousa, Alioscka A.; Hassan, Sergio A.; Knittel, Luiza L.; Balbo, Andrea; Aronova, Maria A.; Brown, Patrick H.; Schuck, Peter; Leapman, Richard D.

    2016-03-01

    Recent in vivo studies have established ultrasmall (<3 nm) gold nanoparticles coated with glutathione (AuGSH) as a promising platform for applications in nanomedicine. However, systematic in vitro investigations to gain a more fundamental understanding of the particles' biointeractions are still lacking. Herein we examined the behavior of ultrasmall AuGSH in vitro, focusing on their ability to resist aggregation and adsorption from serum proteins. Despite having net negative charge, AuGSH particles were colloidally stable in biological media and able to resist binding from serum proteins, in agreement with the favorable bioresponses reported for AuGSH in vivo. However, our results revealed disparate behaviors depending on nanoparticle size: particles between 2 and 3 nm in core diameter were found to readily aggregate in biological media, whereas those strictly under 2 nm were exceptionally stable. Molecular dynamics simulations provided microscopic insight into interparticle interactions leading to aggregation and their sensitivity to the solution composition and particle size. These results have important implications, in that seemingly small variations in size can impact the biointeractions of ultrasmall AuGSH, and potentially of other ultrasmall nanoparticles as well.Recent in vivo studies have established ultrasmall (<3 nm) gold nanoparticles coated with glutathione (AuGSH) as a promising platform for applications in nanomedicine. However, systematic in vitro investigations to gain a more fundamental understanding of the particles' biointeractions are still lacking. Herein we examined the behavior of ultrasmall AuGSH in vitro, focusing on their ability to resist aggregation and adsorption from serum proteins. Despite having net negative charge, AuGSH particles were colloidally stable in biological media and able to resist binding from serum proteins, in agreement with the favorable bioresponses reported for AuGSH in vivo. However, our results revealed disparate

  3. Cytotoxicity of Ultrasmall Gold Nanoparticles on Planktonic and Biofilm Encapsulated Gram-Positive Staphylococci.

    PubMed

    Boda, Sunil Kumar; Broda, Janine; Schiefer, Frank; Weber-Heynemann, Josefine; Hoss, Mareike; Simon, Ulrich; Basu, Bikramjit; Jahnen-Dechent, Willi

    2015-07-01

    The emergence of multidrug resistant bacteria, especially biofilm-associated Staphylococci, urgently requires novel antimicrobial agents. The antibacterial activity of ultrasmall gold nanoparticles (AuNPs) is tested against two gram positive: S. aureus and S. epidermidis and two gram negative: Escherichia coli and Pseudomonas aeruginosa strains. Ultrasmall AuNPs with core diameters of 0.8 and 1.4 nm and a triphenylphosphine-monosulfonate shell (Au0.8MS and Au1.4MS) both have minimum inhibitory concentration (MIC) and minimum bactericidal concentration of 25 × 10(-6) m [Au]. Disc agar diffusion test demonstrates greater bactericidal activity of the Au0.8MS nanoparticles over Au1.4MS. In contrast, thiol-stabilized AuNPs with a diameter of 1.9 nm (AuroVist) cause no significant toxicity in any of the bacterial strains. Ultrasmall AuNPs cause a near 5 log bacterial growth reduction in the first 5 h of exposure, and incomplete recovery after 21 h. Bacteria show marked membrane blebbing and lysis in biofilm-associated bacteria treated with ultrasmall AuNP. Importantly, a twofold MIC dosage of Au0.8MS and Au1.4MS each cause around 80%-90% reduction in the viability of Staphylococci enveloped in biofilms. Altogether, this study demonstrates potential therapeutic activity of ultrasmall AuNPs as an effective treatment option against staphylococcal infections. PMID:25712910

  4. Biointeractions of ultrasmall glutathione-coated gold nanoparticles: effect of small size variations.

    PubMed

    Sousa, Alioscka A; Hassan, Sergio A; Knittel, Luiza L; Balbo, Andrea; Aronova, Maria A; Brown, Patrick H; Schuck, Peter; Leapman, Richard D

    2016-03-28

    Recent in vivo studies have established ultrasmall (<3 nm) gold nanoparticles coated with glutathione (AuGSH) as a promising platform for applications in nanomedicine. However, systematic in vitro investigations to gain a more fundamental understanding of the particles' biointeractions are still lacking. Herein we examined the behavior of ultrasmall AuGSH in vitro, focusing on their ability to resist aggregation and adsorption from serum proteins. Despite having net negative charge, AuGSH particles were colloidally stable in biological media and able to resist binding from serum proteins, in agreement with the favorable bioresponses reported for AuGSH in vivo. However, our results revealed disparate behaviors depending on nanoparticle size: particles between 2 and 3 nm in core diameter were found to readily aggregate in biological media, whereas those strictly under 2 nm were exceptionally stable. Molecular dynamics simulations provided microscopic insight into interparticle interactions leading to aggregation and their sensitivity to the solution composition and particle size. These results have important implications, in that seemingly small variations in size can impact the biointeractions of ultrasmall AuGSH, and potentially of other ultrasmall nanoparticles as well. PMID:26934984

  5. Ultradispersed Cobalt Ferrite Nanoparticles Assembled in Graphene Aerogel for Continuous Photo-Fenton Reaction and Enhanced Lithium Storage Performance

    PubMed Central

    Qiu, Bocheng; Deng, Yuanxin; Du, Mengmeng; Xing, Mingyang; Zhang, Jinlong

    2016-01-01

    The Photo-Fenton reaction is an advanced technology to eliminate organic pollutants in environmental chemistry. Moreover, the conversion rate of Fe3+/Fe2+ and utilization rate of H2O2 are significant factors in Photo-Fenton reaction. In this work, we reported three dimensional (3D) hierarchical cobalt ferrite/graphene aerogels (CoFe2O4/GAs) composites by the in situ growing CoFe2O4 crystal seeds on the graphene oxide (GO) followed by the hydrothermal process. The resulting CoFe2O4/GAs composites demonstrated 3D hierarchical pore structure with mesopores (14~18 nm), macropores (50~125 nm), and a remarkable surface area (177.8 m2 g−1). These properties endowed this hybrid with the high and recyclable Photo-Fenton activity for methyl orange pollutant degradation. More importantly, the CoFe2O4/GAs composites can keep high Photo-Fenton activity in a wide pH. Besides, the CoFe2O4/GAs composites also exhibited excellent cyclic performance and good rate capability. The 3D framework can not only effectively prevent the volume expansion and aggregation of CoFe2O4 nanoparticles during the charge/discharge processes for Lithium-ion batteries (LIBs), but also shorten lithium ions and electron diffusion length in 3D pathways. These results indicated a broaden application prospect of 3D-graphene based hybrids in wastewater treatment and energy storage. PMID:27373343

  6. Ultradispersed Cobalt Ferrite Nanoparticles Assembled in Graphene Aerogel for Continuous Photo-Fenton Reaction and Enhanced Lithium Storage Performance.

    PubMed

    Qiu, Bocheng; Deng, Yuanxin; Du, Mengmeng; Xing, Mingyang; Zhang, Jinlong

    2016-01-01

    The Photo-Fenton reaction is an advanced technology to eliminate organic pollutants in environmental chemistry. Moreover, the conversion rate of Fe(3+)/Fe(2+) and utilization rate of H2O2 are significant factors in Photo-Fenton reaction. In this work, we reported three dimensional (3D) hierarchical cobalt ferrite/graphene aerogels (CoFe2O4/GAs) composites by the in situ growing CoFe2O4 crystal seeds on the graphene oxide (GO) followed by the hydrothermal process. The resulting CoFe2O4/GAs composites demonstrated 3D hierarchical pore structure with mesopores (14~18 nm), macropores (50~125 nm), and a remarkable surface area (177.8 m(2 )g(-1)). These properties endowed this hybrid with the high and recyclable Photo-Fenton activity for methyl orange pollutant degradation. More importantly, the CoFe2O4/GAs composites can keep high Photo-Fenton activity in a wide pH. Besides, the CoFe2O4/GAs composites also exhibited excellent cyclic performance and good rate capability. The 3D framework can not only effectively prevent the volume expansion and aggregation of CoFe2O4 nanoparticles during the charge/discharge processes for Lithium-ion batteries (LIBs), but also shorten lithium ions and electron diffusion length in 3D pathways. These results indicated a broaden application prospect of 3D-graphene based hybrids in wastewater treatment and energy storage. PMID:27373343

  7. Ultradispersed Cobalt Ferrite Nanoparticles Assembled in Graphene Aerogel for Continuous Photo-Fenton Reaction and Enhanced Lithium Storage Performance

    NASA Astrophysics Data System (ADS)

    Qiu, Bocheng; Deng, Yuanxin; Du, Mengmeng; Xing, Mingyang; Zhang, Jinlong

    2016-07-01

    The Photo-Fenton reaction is an advanced technology to eliminate organic pollutants in environmental chemistry. Moreover, the conversion rate of Fe3+/Fe2+ and utilization rate of H2O2 are significant factors in Photo-Fenton reaction. In this work, we reported three dimensional (3D) hierarchical cobalt ferrite/graphene aerogels (CoFe2O4/GAs) composites by the in situ growing CoFe2O4 crystal seeds on the graphene oxide (GO) followed by the hydrothermal process. The resulting CoFe2O4/GAs composites demonstrated 3D hierarchical pore structure with mesopores (14~18 nm), macropores (50~125 nm), and a remarkable surface area (177.8 m2 g‑1). These properties endowed this hybrid with the high and recyclable Photo-Fenton activity for methyl orange pollutant degradation. More importantly, the CoFe2O4/GAs composites can keep high Photo-Fenton activity in a wide pH. Besides, the CoFe2O4/GAs composites also exhibited excellent cyclic performance and good rate capability. The 3D framework can not only effectively prevent the volume expansion and aggregation of CoFe2O4 nanoparticles during the charge/discharge processes for Lithium-ion batteries (LIBs), but also shorten lithium ions and electron diffusion length in 3D pathways. These results indicated a broaden application prospect of 3D-graphene based hybrids in wastewater treatment and energy storage.

  8. Ultradispersed Cobalt Ferrite Nanoparticles Assembled in Graphene Aerogel for Continuous Photo-Fenton Reaction and Enhanced Lithium Storage Performance.

    PubMed

    Qiu, Bocheng; Deng, Yuanxin; Du, Mengmeng; Xing, Mingyang; Zhang, Jinlong

    2016-07-04

    The Photo-Fenton reaction is an advanced technology to eliminate organic pollutants in environmental chemistry. Moreover, the conversion rate of Fe(3+)/Fe(2+) and utilization rate of H2O2 are significant factors in Photo-Fenton reaction. In this work, we reported three dimensional (3D) hierarchical cobalt ferrite/graphene aerogels (CoFe2O4/GAs) composites by the in situ growing CoFe2O4 crystal seeds on the graphene oxide (GO) followed by the hydrothermal process. The resulting CoFe2O4/GAs composites demonstrated 3D hierarchical pore structure with mesopores (14~18 nm), macropores (50~125 nm), and a remarkable surface area (177.8 m(2 )g(-1)). These properties endowed this hybrid with the high and recyclable Photo-Fenton activity for methyl orange pollutant degradation. More importantly, the CoFe2O4/GAs composites can keep high Photo-Fenton activity in a wide pH. Besides, the CoFe2O4/GAs composites also exhibited excellent cyclic performance and good rate capability. The 3D framework can not only effectively prevent the volume expansion and aggregation of CoFe2O4 nanoparticles during the charge/discharge processes for Lithium-ion batteries (LIBs), but also shorten lithium ions and electron diffusion length in 3D pathways. These results indicated a broaden application prospect of 3D-graphene based hybrids in wastewater treatment and energy storage.

  9. Facile growth of well-dispersed and ultra-small MoS2 nanodots in ordered mesoporous silica nanoparticles.

    PubMed

    Wang, Yi; Wang, Shanshan; Li, Chengyi; Qian, Min; Bu, Juan; Wang, Jianxin; Huang, Rongqin

    2016-08-11

    A facile one-step solvothermal method was developed for the homogeneously confined growth of ultra-small (∼1.5 nm) and monodispersed 2H phase MoS2 nanodots into mesoporous silica nanoparticles (MSNs). PMID:27387440

  10. Facile growth of well-dispersed and ultra-small MoS2 nanodots in ordered mesoporous silica nanoparticles.

    PubMed

    Wang, Yi; Wang, Shanshan; Li, Chengyi; Qian, Min; Bu, Juan; Wang, Jianxin; Huang, Rongqin

    2016-08-11

    A facile one-step solvothermal method was developed for the homogeneously confined growth of ultra-small (∼1.5 nm) and monodispersed 2H phase MoS2 nanodots into mesoporous silica nanoparticles (MSNs).

  11. A facile one-pot method to synthesize ultrasmall core-shell superparamagnetic and upconversion nanoparticles.

    PubMed

    Cheng, Qian; Guo, Hongxuan; Li, Yu; Liu, Shouxin; Sui, Jiehe; Cai, Wei

    2016-08-01

    Ultrasmall core-shell Fe3O4@NaYF4:Yb(3+)/Er(3+) nanoparticles with bifunctional properties have been successfully synthesized via one pot thermolysis method using oleylamine as both solvent and stabilizer. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), upconversion (UC) luminescence spectra and the physical properties measurement system (PPMS) were used to characterize the resulting samples. The synthesized samples have uniform morphology with a mean size of 14.5nm and excellent dispersibility. Moreover, these nanoparticles exhibit superparamagnetic behaviour with saturation magnetization of 8.45emμ/g and efficient up-conversion emission with a two-photon induced process when excited by a 980nm laser. These results suggest that the synthesized ultrasmall bifunctional nanoparticles may find many biomedical applications, such as clinical diagnosis and treatment of cancers.

  12. Ultra-small lipid-polymer hybrid nanoparticles for tumor-penetrating drug delivery

    NASA Astrophysics Data System (ADS)

    Dehaini, Diana; Fang, Ronnie H.; Luk, Brian T.; Pang, Zhiqing; Hu, Che-Ming J.; Kroll, Ashley V.; Yu, Chun Lai; Gao, Weiwei; Zhang, Liangfang

    2016-07-01

    Lipid-polymer hybrid nanoparticles, consisting of a polymeric core coated by a layer of lipids, are a class of highly scalable, biodegradable nanocarriers that have shown great promise in drug delivery applications. Here, we demonstrate the facile synthesis of ultra-small, sub-25 nm lipid-polymer hybrid nanoparticles using an adapted nanoprecipitation approach and explore their utility for targeted delivery of a model chemotherapeutic. The fabrication process is first optimized to produce a monodisperse population of particles that are stable under physiological conditions. It is shown that these ultra-small hybrid nanoparticles can be functionalized with a targeting ligand on the surface and loaded with drug inside the polymeric matrix. Further, the in vivo fate of the nanoparticles after intravenous injection is characterized by examining the blood circulation and biodistribution. In a final proof-of-concept study, targeted ultra-small hybrid nanoparticles loaded with the cancer drug docetaxel are used to treat a mouse tumor model and demonstrate improved efficacy compared to a clinically available formulation of the drug. The ability to synthesize a significantly smaller version of the established lipid-polymer hybrid platform can ultimately enhance its applicability across a wider range of applications.

  13. Confirmation of disordered structure of ultrasmall CdSe nanoparticles from X-ray atomic pair distribution function analysis.

    PubMed

    Yang, Xiaohao; Masadeh, Ahmad S; McBride, James R; Božin, Emil S; Rosenthal, Sandra J; Billinge, Simon J L

    2013-06-14

    The atomic pair distribution function (PDF) analysis of X-ray powder diffraction data has been used to study the structure of small and ultra-small CdSe nanoparticles. A method is described that uses a wurtzite and zinc-blende mixed phase model to account for stacking faults in CdSe particles. The mixed-phase model successfully describes the structure of nanoparticles larger than 2 nm yielding a stacking fault density of about 30%. However, for ultrasmall nanoparticles smaller than 2 nm, the models cannot fit the experimental PDF showing that the structure is significantly modified from that of larger particles and the bulk. The observation of a significant change in the average structure at ultra-small size is likely to explain the unusual properties of the ultrasmall particles such as their white light emitting ability.

  14. Probing the interaction induced conformation transitions in acid phosphatase with cobalt ferrite nanoparticles: Relation to inhibition and bio-activity of Chlorella vulgaris acid phosphatase.

    PubMed

    Ahmad, Farooq; Zhou, Xing; Yao, Hongzhou; Zhou, Ying; Xu, Chao

    2016-09-01

    The present study explored the interaction and kinetics of cobalt ferrite nanoparticles (NPs) with acid phosphatase (ACP) by utilizing diverse range of spectroscopic techniques. The results corroborate, the CoFe2O4 NPs cause fluorescence quenching in ACP by static quenching mechanism. The negative values of van't Hoff thermodynamic expressions (ΔH=-0.3293Jmol(-1)K(-1) and ΔG=-3.960kJmol(-1)K(-1)) corroborate the spontaneity and exothermic nature of static quenching. The positive value of ΔS (13.2893Jmol(-1)K(-1)) corroborate that major contributors of higher and stronger binding affinity among CoFe2O4 NPs with ACP were electrostatic. In addition, FTIR, UV-CD, UV-vis spectroscopy and three dimensional fluorescence (3D) techniques confirmed that CoFe2O4 NPs binding induces microenvironment perturbations leading to secondary and tertiary conformation changes in ACP to a great extent. Furthermore, synchronous fluorescence spectroscopy (SFS) affirmed the comparatively significant changes in microenvironment around tryptophan (Trp) residue by CoFe2O4 NPs. The effect of CoFe2O4 NPs on the activation kinetics of ACP was further examined in Chlorella vulgaris. Apparent Michaelis constant (Km) values of 0.57 and 26.5mM with activation energy values of 0.538 and 3.428kJmol(-1) were determined without and with 200μM CoFe2O4 NPs. Apparent Vmax value of -7Umml(-1) corroborate that enzyme active sites were completely captured by the NPs leaving no space for the substrate. The results confirmed that CoFe2O4 NPs ceased the activity by unfolding of ACP enzyme. This suggests CoFe2O4 NPs perturbed the enzyme activity by transitions in conformation and hence the metabolic activity of ACP. This study provides the pavement for novel and simple approach of using sensitive biomarkers for sensing NPs in environment. PMID:27209386

  15. Unconventional route to encapsulated ultrasmall gold nanoparticles for high-temperature catalysis.

    PubMed

    Zhang, Tingting; Zhao, Hongyu; He, Shengnan; Liu, Kai; Liu, Hongyang; Yin, Yadong; Gao, Chuanbo

    2014-07-22

    Ultrasmall gold nanoparticles (us-AuNPs, <3 nm) have been recently recognized as surprisingly active and extraordinarily effective green catalysts. Their stability against sintering during reactions, however, remains a serious issue for practical applications. Encapsulating such small nanoparticles in a layer of porous silica can dramatically enhance the stability, but it has been extremely difficult to achieve using conventional sol-gel coating methods due to the weak metal/oxide affinity. In this work, we address this challenge by developing an effective protocol for the synthesis of us-AuNP@SiO2 single-core/shell nanospheres. More specifically, we take an alternative route by starting with ultrasmall gold hydroxide nanoparticles, which have excellent affinity to silica, then carrying out controllable silica coating in reverse micelles, and finally converting gold hydroxide particles into well-protected us-AuNPs. With a single-core/shell configuration that prevents sintering of nearby us-AuNPs and amino group modification of the Au/SiO2 interface that provides additional coordinating interactions, the resulting us-AuNP@SiO2 nanospheres are highly stable at high temperatures and show high activity in catalytic CO oxidation reactions. A dramatic and continuous increase in the catalytic activity has been observed when the size of the us-AuNPs decreases from 2.3 to 1.5 nm, which reflects the intrinsic size effect of the Au nanoparticles on an inert support. The synthesis scheme described in this work is believed to be extendable to many other ultrasmall metal@oxide nanostructures for much broader catalytic applications.

  16. Magnetoelectric studies on CoFe2O4/0.5(BaTi0.8Zr0.2O3)-0.5(Ba0.7Ca0.3TiO3) lead-free bilayer thin films derived by the chemical solution deposition

    NASA Astrophysics Data System (ADS)

    Venkata Ramana, E.; Zavašnik, Janez; Graça, M. P. F.; Valente, M. A.

    2016-08-01

    Lead-free multiferroic bilayer thin films were fabricated on (111)Pt/Si substrate via a simple sol-gel chemical solution deposition, by altering the position of piezoelectric (Ba0.85Ca0.15) (Ti0.9Zr0.1)O3 (BCTZO) and ferromagnetic CoFe2O4 (CFO). Single layer BCTZO experiences the out-of-plane compressive stress, while this layer is under tensile strain in both the bilayers. The microstructural study confirms the formation of bilayers with expected chemical composition composed of multiple well-developed crystallites having no crystallographic dependencies. Thin films of BCTZO and CFO/BCTZO exhibited saturated ferroelectric hysteresis loops at room temperature with a Pr of 7.2 and 5.6 μC/cm2. The magnetic field induced shift in phonon vibrations coupled with direct magnetoelectric (ME) measurements demonstrated a stress-mediated coupling mechanism in the bilayers. We found a superior ME coefficient (105 MV/cm Oe) and dielectric tunability (˜52%) for CFO/BCTZO bilayer compared to the BCTZO/CFO bilayer, which demonstrates that the modification of strain state in bilayers is useful for the desired ME coupling. The BCTZO having piezoelectricity on par with that of lead-based ones can be useful to tailor lead-free ME applications.

  17. Geometrically confined ultrasmall gadolinium oxide nanoparticles boost the T1 contrast ability

    NASA Astrophysics Data System (ADS)

    Ni, Kaiyuan; Zhao, Zhenghuan; Zhang, Zongjun; Zhou, Zijian; Yang, Li; Wang, Lirong; Ai, Hua; Gao, Jinhao

    2016-02-01

    High-performance magnetic resonance imaging (MRI) contrast agents and novel contrast enhancement strategies are urgently needed for sensitive and accurate diagnosis. Here we report a strategy to construct a new T1 contrast agent based on the Solomon-Bloembergen-Morgan (SBM) theory. We loaded the ultrasmall gadolinium oxide nanoparticles into worm-like interior channels of mesoporous silica nanospheres (Gd2O3@MSN nanocomposites). This unique structure endows the nanocomposites with geometrical confinement, high molecular tumbling time, and a large coordinated number of water molecules, which results in a significant enhancement of the T1 contrast with longitudinal proton relaxivity (r1) as high as 45.08 mM-1 s-1. Such a high r1 value of Gd2O3@MSN, compared to those of ultrasmall Gd2O3 nanoparticles and gadolinium-based clinical contrast agents, is mainly attributed to the strong geometrical confinement effect. This strategy provides new guidance for developing various high-performance T1 contrast agents for sensitive imaging and disease diagnosis.High-performance magnetic resonance imaging (MRI) contrast agents and novel contrast enhancement strategies are urgently needed for sensitive and accurate diagnosis. Here we report a strategy to construct a new T1 contrast agent based on the Solomon-Bloembergen-Morgan (SBM) theory. We loaded the ultrasmall gadolinium oxide nanoparticles into worm-like interior channels of mesoporous silica nanospheres (Gd2O3@MSN nanocomposites). This unique structure endows the nanocomposites with geometrical confinement, high molecular tumbling time, and a large coordinated number of water molecules, which results in a significant enhancement of the T1 contrast with longitudinal proton relaxivity (r1) as high as 45.08 mM-1 s-1. Such a high r1 value of Gd2O3@MSN, compared to those of ultrasmall Gd2O3 nanoparticles and gadolinium-based clinical contrast agents, is mainly attributed to the strong geometrical confinement effect. This strategy

  18. Nanoencapsulation of ultra-small superparamagnetic particles of iron oxide into human serum albumin nanoparticles

    PubMed Central

    Altinok, Mahmut; Urfels, Stephan; Bauer, Johann

    2014-01-01

    Summary Human serum albumin nanoparticles have been utilized as drug delivery systems for a variety of medical applications. Since ultra-small superparamagnetic particles of iron oxide (USPIO) are used as contrast agents in magnetic resonance imaging, their encapsulation into the protein matrix enables the synthesis of diagnostic and theranostic agents by surface modification and co-encapsulation of active pharmaceutical ingredients. The present investigation deals with the surface modification and nanoencapsulation of USPIO into an albumin matrix by using ethanolic desolvation. Particles of narrow size distribution and with a defined particle structure have been achieved. PMID:25551054

  19. Use of a polyol liquid collection medium to obtain ultrasmall magnetic nanoparticles by laser pyrolysis.

    PubMed

    Martínez, G; Malumbres, A; Mallada, R; Hueso, J L; Irusta, S; Bomatí-Miguel, O; Santamaría, J

    2012-10-26

    The present work addresses the main bottleneck in the synthesis of magnetic nanoparticles by laser pyrolysis. Since the introduction of laser pyrolysis for the production of nanoparticles nearly three decades ago, this method has been repeatedly presented as a highly promising alternative, on account of two main characteristics: (i) its flexibility, since nanoparticles can be formed from a wide variety of precursors in both gas and liquid phase, and (ii) its continuous nature, avoiding the intrinsic variability of batch processing. However, the results reported to date invariably show considerable aggregation of the obtained nanoparticles, which strongly limits their application in most fields. In this work, we have been able to circumvent this problem by collecting the particles in a polyol liquid medium. This method prevents the formation of aggregates and renders a uniform distribution of well dispersed ultrasmall nanoparticles (<4 nm) in a water-compatible solvent. We consider that the effectiveness of this novel collection method for the production of well-dispersed magnetic nanoparticles will be of high interest to a wide range of scientists working in the nanoparticle synthesis field and may enable new applications wherever there is a strict requirement for non-agglomerated nanoparticles.

  20. Geometrically confined ultrasmall gadolinium oxide nanoparticles boost the T(1) contrast ability.

    PubMed

    Ni, Kaiyuan; Zhao, Zhenghuan; Zhang, Zongjun; Zhou, Zijian; Yang, Li; Wang, Lirong; Ai, Hua; Gao, Jinhao

    2016-02-14

    High-performance magnetic resonance imaging (MRI) contrast agents and novel contrast enhancement strategies are urgently needed for sensitive and accurate diagnosis. Here we report a strategy to construct a new T1 contrast agent based on the Solomon-Bloembergen-Morgan (SBM) theory. We loaded the ultrasmall gadolinium oxide nanoparticles into worm-like interior channels of mesoporous silica nanospheres (Gd2O3@MSN nanocomposites). This unique structure endows the nanocomposites with geometrical confinement, high molecular tumbling time, and a large coordinated number of water molecules, which results in a significant enhancement of the T1 contrast with longitudinal proton relaxivity (r1) as high as 45.08 mM(-1) s(-1). Such a high r1 value of Gd2O3@MSN, compared to those of ultrasmall Gd2O3 nanoparticles and gadolinium-based clinical contrast agents, is mainly attributed to the strong geometrical confinement effect. This strategy provides new guidance for developing various high-performance T1 contrast agents for sensitive imaging and disease diagnosis.

  1. Rapid synthesis of PEGylated ultrasmall gadolinium oxide nanoparticles for cell labeling and tracking with MRI.

    PubMed

    Faucher, Luc; Tremblay, Mélanie; Lagueux, Jean; Gossuin, Yves; Fortin, Marc-André

    2012-09-26

    Ultrasmall paramagnetic Gd(2)O(3) nanoparticles have been developed as contrast agents for molecular and cellular preclinical MRI procedures. These small particles (mean diameter <5 nm) have the highest Gd density of all paramagnetic contrast agents. They generate strong positive contrast enhancement in T(1)-weighted MRI. Signal enhancement is modulated by the interactions of water molecules with Gd, and very small particles provide the optimal surface-to-volume ratios necessary to reach high relaxivities. Conventional Gd(2)O(3) nanocrystal synthesis techniques, and subsequent polyethylene glycol (PEG) grafting procedures are usually time-consuming and recovery losses are also limitative. The present study reports on a new, fast, and efficient one-pot Gd(2)O(3) synthesis technique that provides PEGylated nanoparticles of very small size (mean diameter = 1.3 nm). Readily coated with PEG, the particles are colloidally stable in aqueous media and provide high longitudial relaxivities and small r(2)/r(1) ratios (r(1) = 14.2 mM(-1) s(-1) at 60 MHz; r(2)/r(1) = 1.20), ideal for T(1)-weighted MRI. In this study, F98 brain cancer cells (glioblastoma multiforme) were labeled with the contrast agent and implanted in vivo (mice brains). The labeled cells appeared positively contrasted at least 48 h after implantation. Each one of the implanted animals developed a brain tumor. The performance of PEG-Gd(2)O(3) was also compared with that of commercially available iron oxide nanoparticles. This study demonstrated that ultrasmall PEG-Gd(2)O(3) nanoparticles provide strong positive contrast enhancement in T(1)-weighted imaging, and allow the visualization of labeled cells implanted in vivo.

  2. Ultrasmall Superparamagnetic Iron Oxide Nanoparticles with Europium(III) DO3A as a Bimodal Imaging Probe.

    PubMed

    Carron, Sophie; Bloemen, Maarten; Vander Elst, Luce; Laurent, Sophie; Verbiest, Thierry; Parac-Vogt, Tatjana N

    2016-03-18

    A new prototype consisting of ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles decorated with europium(III) ions encapsulated in a DO3A organic scaffold was designed as a platform for further development of bimodal contrast agents for MRI and optical imaging. The USPIO nanoparticles act as negative MRI contrast agents, whereas the europium(III) ion is a luminophore that is suitable for use in optical imaging detection. The functionalized USPIO nanoparticles were characterized by TEM, DLS, XRD, FTIR, and TXRF analysis, and a full investigation of the relaxometric and optical properties was conducted. The typical luminescence emission of europium(III) was observed and the main red emission wavelength was found at 614 nm. The relaxometric study of these ultrasmall nanoparticles showed r2 values of 114.8 mM(-1) Fes(-1) at 60 MHz, which is nearly double the r2 relaxivity of Sinerem(®).

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

    PubMed

    Lisjak, Darja; Jenuš, Petra; Mertelj, Alenka

    2014-06-10

    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

  4. Coupling of HPLC with electrospray ionization mass spectrometry for studying the aging of ultrasmall multifunctional gadolinium-based silica nanoparticles.

    PubMed

    Truillet, Charles; Lux, François; Tillement, Olivier; Dugourd, Philippe; Antoine, Rodolphe

    2013-11-01

    Sub-5 nm multimodal nanoparticles have great potential for theranostic applications due to their easy renal elimination combined with complementary imaging properties and therapeutic facilities. Their potential clinical use requires the full characterization of not only the nanoparticle but also all its possible degradation products. We have recently proposed new ultrasmall gadolinium-based nanoparticles for multimodal imaging and radiosensitization. The aim of this article is to describe an analytical tool to characterize degradation products in a highly diluted medium. We demonstrate that HPLC coupled to electrospray ionization mass spectrometry (ESI-MS) can be used in order to determine precisely the composition of nanoparticles and their degradation fragments during aging.

  5. Impact of agglomeration on the relaxometric properties of paramagnetic ultra-small gadolinium oxide nanoparticles.

    PubMed

    Faucher, Luc; Gossuin, Yves; Hocq, Aline; Fortin, Marc-André

    2011-07-22

    Ultra-small gadolinium oxide nanoparticles (US-Gd(2)O(3)) are used to provide 'positive' contrast effects in magnetic resonance imaging (MRI), and are being considered for molecular and cellular imaging applications. However, these nanoparticles can aggregate over time in aqueous medium, as well as when internalized into cells. This study is aimed at measuring in vitro, in aqueous medium, the impact of aggregation on the relaxometric properties of paramagnetic US-Gd(2)O(3) particles. First, the nanoparticle core size as well as aggregation behaviour was assessed by HRTEM. DLS (hydrodynamic diameter) was used to measure the hydrodynamic diameter of nanoparticles and nanoaggregates. The relaxometric properties were measured by NMRD profiling, as well as with (1)H NMR relaxometers. Then, the positive contrast enhancement effect was assessed by using magnetic resonance scanners (at 1.5 and 7 T). At every magnetic field, the longitudinal relaxivity (r(1)) decreased upon agglomeration, while remaining high enough to provide positive contrast. On the other hand, the transverse relaxivity (r(2)) slightly decreased at 0.47 and 1.41 T, but it was enhanced at higher fields (7 and 11.7 T) upon agglomeration. All NMRD profiles revealed a characteristic relaxivity peak in the range 60-100 MHz, suggesting the possibility to use US-Gd(2)O(3) as an efficient 'positive-T(1)' contrast agent at clinical magnetic fields (1-3 T), in spite of aggregation.

  6. Impact of agglomeration on the relaxometric properties of paramagnetic ultra-small gadolinium oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Faucher, Luc; Gossuin, Yves; Hocq, Aline; Fortin, Marc-André

    2011-07-01

    Ultra-small gadolinium oxide nanoparticles (US-Gd2O3) are used to provide 'positive' contrast effects in magnetic resonance imaging (MRI), and are being considered for molecular and cellular imaging applications. However, these nanoparticles can aggregate over time in aqueous medium, as well as when internalized into cells. This study is aimed at measuring in vitro, in aqueous medium, the impact of aggregation on the relaxometric properties of paramagnetic US-Gd2O3 particles. First, the nanoparticle core size as well as aggregation behaviour was assessed by HRTEM. DLS (hydrodynamic diameter) was used to measure the hydrodynamic diameter of nanoparticles and nanoaggregates. The relaxometric properties were measured by NMRD profiling, as well as with 1H NMR relaxometers. Then, the positive contrast enhancement effect was assessed by using magnetic resonance scanners (at 1.5 and 7 T). At every magnetic field, the longitudinal relaxivity (r1) decreased upon agglomeration, while remaining high enough to provide positive contrast. On the other hand, the transverse relaxivity (r2) slightly decreased at 0.47 and 1.41 T, but it was enhanced at higher fields (7 and 11.7 T) upon agglomeration. All NMRD profiles revealed a characteristic relaxivity peak in the range 60-100 MHz, suggesting the possibility to use US-Gd2O3 as an efficient 'positive-T1' contrast agent at clinical magnetic fields (1-3 T), in spite of aggregation.

  7. Various ligand-coated ultrasmall gadolinium-oxide nanoparticles: Water proton relaxivity and in-vivo T1 MR image

    NASA Astrophysics Data System (ADS)

    Park, Ja Young; Kim, Sung June; Lee, Gang Ho; Jin, Seonguk; Chang, Yongmin; Bae, Ji Eun; Chae, Kwon Seok

    2015-04-01

    Surface coating of nanoparticles with ligands is essential in magnetic resonance imaging (MRI) because of solubility in water and biocompatibility. In this study, five organic molecules were used for surface coating of ultrasmall gadolinium-oxide (Gd2O3) nanoparticles (d avg = 2.0 nm). All of the samples showed large longitudinal (r1) and transverse (r2) water proton relaxivities with r2/r1 ratios that were close to one, corresponding to ideal conditions for T1 MRI contrast agents. Finally, in-vivo T1 MR images were acquired to prove the effectiveness of the surface-coated ultrasmall Gd2O3 nanoparticles as a T1 MRI contrast agent.

  8. Charge-controlled nanoprecipitation as a modular approach to ultrasmall polymer nanocarriers: making bright and stable nanoparticles.

    PubMed

    Reisch, Andreas; Runser, Anne; Arntz, Youri; Mély, Yves; Klymchenko, Andrey S

    2015-05-26

    Ultrasmall polymer nanoparticles are rapidly gaining importance as nanocarriers for drugs and contrast agents. Here, a straightforward modular approach to efficiently loaded and stable sub-20-nm polymer particles is developed. In order to obtain ultrasmall polymer nanoparticles, we investigated the influence of one to two charged groups per polymer chain on the size of particles obtained by nanoprecipitation. Negatively charged carboxylate and sulfonate or positively charged trimethylammonium groups were introduced into the polymers poly(d,l-lactide-co-glycolide) (PLGA), polycaprolactone (PCL), and poly(methyl methacrylate) (PMMA). According to dynamic light scattering, atomic force and electron microscopy, the presence of one to two charged groups per polymer chain can strongly reduce the size of polymer nanoparticles made by nanoprecipitation. The particle size can be further decreased to less than 15 nm by decreasing the concentration of polymer in the solvent used for nanoprecipitation. We then show that even very small nanocarriers of 15 nm size preserve the capacity to encapsulate large amounts of ionic dyes with bulky counterions at efficiencies >90%, which generates polymer nanoparticles 10-fold brighter than quantum dots of the same size. Postmodification of their surface with the PEG containing amphiphiles Tween 80 and pluronic F-127 led to particles that were stable under physiological conditions and in the presence of 10% fetal bovine serum. This modular route could become a general method for the preparation of ultrasmall polymer nanoparticles as nanocarriers of contrast agents and drugs.

  9. Ultrasmall and phase-pure W2C nanoparticles for efficient electrocatalytic and photoelectrochemical hydrogen evolution

    PubMed Central

    Gong, Qiufang; Wang, Yu; Hu, Qi; Zhou, Jigang; Feng, Renfei; Duchesne, Paul N.; Zhang, Peng; Chen, Fengjiao; Han, Na; Li, Yafei; Jin, Chuanhong; Li, Yanguang; Lee, Shuit-Tong

    2016-01-01

    Earlier research has been primarily focused on WC as one of the most promising earth-abundant electrocatalysts for hydrogen evolution reaction (HER), whereas the other compound in this carbide family—W2C—has received far less attention. Our theoretical calculations suggest that such a focus is misplaced and W2C is potentially more HER-active than WC. Nevertheless, the preparation of phase pure and sintering-free W2C nanostructures represents a formidable challenge. Here we develop an improved carburization method and successfully prepare ultrasmall and phase-pure W2C nanoparticles. When evaluated for HER electrocatalysis, W2C nanoparticles exhibit a small onset overpotential of 50 mV, a Tafel slope of 45 mV dec−1 and outstanding long-term cycling stability, which are dramatically improved over all existing WC-based materials. In addition, the integration of W2C nanoparticles with p-type Si nanowires enables highly active and sustainable solar-driven hydrogen production. Our results highlight the great potential of this traditionally non-popular material in HER electrocatalysis. PMID:27752046

  10. Adsorption kinetics of plasma proteins on ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles.

    PubMed

    Jansch, M; Stumpf, P; Graf, C; Rühl, E; Müller, R H

    2012-05-30

    In this study the kinetics of plasma protein adsorption onto ultrasmall superparamagnetic iron oxide (USPIO) particles have been analyzed and compared to previously published kinetic studies on polystyrene particles (PS particles), oil-in-water nanoemulsions and solid lipid nanoparticles (SLNs). SPIO and USPIO nanoparticles are commonly used as magnetic resonance imaging (MRI) enhancers for tumor imaging as well as in drug delivery applications. Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) has been used to determine the plasma protein adsorption onto the citrate/triethylene glycol-stabilized iron oxide surface. The results indicate that the existence of a Vroman effect, a displacement of previously adsorbed abundant proteins, such as albumin or fibrinogen, respectively, on USPIO particles has to be denied. Previously, identical findings have been reported for oil-in-water nanoemulsions. Furthermore, the protein adsorption kinetics differs dramatically from that of other solid drug delivery systems (PS, SLN). More relevant for the in vivo fate of long circulating particles is the protein corona after several minutes or even hours. Interestingly, the patterns received after an incubation time of 0.5 min to 240 min are found to be qualitatively and quantitatively similar. This leads to the assumption of a long-lived ("hard") protein corona around the iron oxide nanoparticles. PMID:22342465

  11. Ultrasmall cationic superparamagnetic iron oxide nanoparticles as nontoxic and efficient MRI contrast agent and magnetic-targeting tool.

    PubMed

    Uchiyama, Mayara Klimuk; Toma, Sergio Hiroshi; Rodrigues, Stephen Fernandes de Paula; Shimada, Ana Lucia Borges; Loiola, Rodrigo Azevedo; Cervantes Rodríguez, Hernán Joel; Oliveira, Pedro Vitoriano; Luz, Maciel Santos; Rabbani, Said Rahnamaye; Toma, Henrique Eisi; Poliselli Farsky, Sandra Helena; Araki, Koiti

    2015-01-01

    Fully dispersible, cationic ultrasmall (7 nm diameter) superparamagnetic iron oxide nanoparticles, exhibiting high relaxivity (178 mM(-1)s(-1) in 0.47 T) and no acute or subchronic toxicity in Wistar rats, were studied and their suitability as contrast agents for magnetic resonance imaging and material for development of new diagnostic and treatment tools demonstrated. After intravenous injection (10 mg/kg body weight), they circulated throughout the vascular system causing no microhemorrhage or thrombus, neither inflammatory processes at the mesentery vascular bed and hepatic sinusoids (leukocyte rolling, adhesion, or migration as evaluated by intravital microscopy), but having been spontaneously concentrated in the liver, spleen, and kidneys, they caused strong negative contrast. The nanoparticles are cleared from kidneys and bladder in few days, whereas the complete elimination from liver and spleen occurred only after 4 weeks. Ex vivo studies demonstrated that cationic ultrasmall superparamagnetic iron oxide nanoparticles caused no effects on hepatic and renal enzymes dosage as well as on leukocyte count. In addition, they were readily concentrated in rat thigh by a magnet showing its potential as magnetically targeted carriers of therapeutic and diagnostic agents. Summarizing, cationic ultrasmall superparamagnetic iron oxide nanoparticles are nontoxic and efficient magnetic resonance imaging contrast agents useful as platform for the development of new materials for application in theranostics.

  12. Ultrasmall cationic superparamagnetic iron oxide nanoparticles as nontoxic and efficient MRI contrast agent and magnetic-targeting tool

    PubMed Central

    Uchiyama, Mayara Klimuk; Toma, Sergio Hiroshi; Rodrigues, Stephen Fernandes; Shimada, Ana Lucia Borges; Loiola, Rodrigo Azevedo; Cervantes Rodríguez, Hernán Joel; Oliveira, Pedro Vitoriano; Luz, Maciel Santos; Rabbani, Said Rahnamaye; Toma, Henrique Eisi; Poliselli Farsky, Sandra Helena; Araki, Koiti

    2015-01-01

    Fully dispersible, cationic ultrasmall (7 nm diameter) superparamagnetic iron oxide nanoparticles, exhibiting high relaxivity (178 mM−1s−1 in 0.47 T) and no acute or subchronic toxicity in Wistar rats, were studied and their suitability as contrast agents for magnetic resonance imaging and material for development of new diagnostic and treatment tools demonstrated. After intravenous injection (10 mg/kg body weight), they circulated throughout the vascular system causing no microhemorrhage or thrombus, neither inflammatory processes at the mesentery vascular bed and hepatic sinusoids (leukocyte rolling, adhesion, or migration as evaluated by intravital microscopy), but having been spontaneously concentrated in the liver, spleen, and kidneys, they caused strong negative contrast. The nanoparticles are cleared from kidneys and bladder in few days, whereas the complete elimination from liver and spleen occurred only after 4 weeks. Ex vivo studies demonstrated that cationic ultrasmall superparamagnetic iron oxide nanoparticles caused no effects on hepatic and renal enzymes dosage as well as on leukocyte count. In addition, they were readily concentrated in rat thigh by a magnet showing its potential as magnetically targeted carriers of therapeutic and diagnostic agents. Summarizing, cationic ultrasmall superparamagnetic iron oxide nanoparticles are nontoxic and efficient magnetic resonance imaging contrast agents useful as platform for the development of new materials for application in theranostics. PMID:26251595

  13. Synthesis of magnetic cobalt ferrite nanoparticles with controlled morphology, monodispersity and composition: the influence of solvent, surfactant, reductant and synthetic conditions.

    PubMed

    Lu, Le T; Dung, Ngo T; Tung, Le D; Thanh, Cao T; Quy, Ong K; Chuc, Nguyen V; Maenosono, Shinya; Thanh, Nguyen T K

    2015-12-14

    In our present work, magnetic cobalt ferrite (CoFe2O4) nanoparticles have been successfully synthesised by thermal decomposition of Fe(III) and Co(II) acetylacetonate compounds in organic solvents in the presence of oleic acid (OA)/ oleylamine (OLA) as surfactants and 1,2-hexadecanediol (HDD) or octadecanol (OCD-ol) as an accelerating agent. As a result, CoFe2O4 nanoparticles of different shapes were tightly controlled in size (range of 4-30 nm) and monodispersity (standard deviation only at ca. 5%). Experimental parameters, such as reaction time, temperature, surfactant concentration, solvent, precursor ratio, and accelerating agent, in particular, the role of HDD, OCD-ol, and OA/OLA have been intensively investigated in detail to discover the best conditions for the synthesis of the above magnetic nanoparticles. The obtained nanoparticles have been successfully applied for producing oriented carbon nanotubes (CNTs), and they have potential to be used in biomedical applications.

  14. Chemisorption of cyanogen chloride by spinel ferrite magnetic nanoparticles.

    PubMed

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

    2013-05-01

    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%.

  15. RGD-functionalized ultrasmall iron oxide nanoparticles for targeted T1-weighted MR imaging of gliomas

    NASA Astrophysics Data System (ADS)

    Luo, Yu; Yang, Jia; Yan, Yu; Li, Jingchao; Shen, Mingwu; Zhang, Guixiang; Mignani, Serge; Shi, Xiangyang

    2015-08-01

    We report a convenient approach to prepare ultrasmall Fe3O4 nanoparticles (NPs) functionalized with an arginylglycylaspartic acid (RGD) peptide for in vitro and in vivo magnetic resonance (MR) imaging of gliomas. In our work, stable sodium citrate-stabilized Fe3O4 NPs were prepared by a solvothermal route. Then, the carboxylated Fe3O4 NPs stabilized with sodium citrate were conjugated with polyethylene glycol (PEG)-linked RGD. The formed ultrasmall RGD-functionalized nanoprobe (Fe3O4-PEG-RGD) was fully characterized using different techniques. We show that these Fe3O4-PEG-RGD particles with a size of 2.7 nm are water-dispersible, stable, cytocompatible and hemocompatible in a given concentration range, and display targeting specificity to glioma cells overexpressing αvβ3 integrin in vitro. With the relatively high r1 relaxivity (r1 = 1.4 mM-1 s-1), the Fe3O4-PEG-RGD particles can be used as an efficient nanoprobe for targeted T1-weighted positive MR imaging of glioma cells in vitro and the xenografted tumor model in vivo via an active RGD-mediated targeting pathway. The developed RGD-functionalized Fe3O4 NPs may hold great promise to be used as a nanoprobe for targeted T1-weighted MR imaging of different αvβ3 integrin-overexpressing cancer cells or biological systems.We report a convenient approach to prepare ultrasmall Fe3O4 nanoparticles (NPs) functionalized with an arginylglycylaspartic acid (RGD) peptide for in vitro and in vivo magnetic resonance (MR) imaging of gliomas. In our work, stable sodium citrate-stabilized Fe3O4 NPs were prepared by a solvothermal route. Then, the carboxylated Fe3O4 NPs stabilized with sodium citrate were conjugated with polyethylene glycol (PEG)-linked RGD. The formed ultrasmall RGD-functionalized nanoprobe (Fe3O4-PEG-RGD) was fully characterized using different techniques. We show that these Fe3O4-PEG-RGD particles with a size of 2.7 nm are water-dispersible, stable, cytocompatible and hemocompatible in a given concentration

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

    PubMed

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

    2012-03-30

    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.

  17. Ultra-small gadolinium oxide nanoparticles to image brain cancer cells in vivo with MRI.

    PubMed

    Faucher, Luc; Guay-Bégin, Andrée-Anne; Lagueux, Jean; Côté, Marie-France; Petitclerc, Eric; Fortin, Marc-André

    2011-01-01

    The majority of contrast agents used in magnetic resonance imaging (MRI) is based on the rare-earth element gadolinium. Gadolinium-based nanoparticles could find promising applications in pre-clinical diagnostic procedures of certain types of cancer, such as glioblastoma multiforme. This is one of the most malignant, lethal and poorly accessible forms of cancer. Recent advances in colloidal nanocrystal synthesis have led to the development of ultra-small crystals of gadolinium oxide (US-Gd(2)O(3), 2-3 nm diameter). As of today, this is the smallest and the densest of all Gd-containing nanoparticles. Cancer cells labeled with a sufficient quantity of this compound appear bright in T(1)-weighted MRI images. Here we demonstrate that US-Gd(2)O(3) can be used to label GL-261 glioblastoma multiforme cells, followed by localization and visualization in vivo using MRI. Very high amounts of Gd are efficiently internalized and retained in cells, as confirmed with TEM and ICP-MS. Labeled cells were visualized in vivo at 1.5 T using the chicken embryo model. This is one more step toward the development of "positively contrasted" cell tracking procedures with MRI.

  18. Ultrasmall dual-modality silica nanoparticle drug conjugates: Design, synthesis, and characterization.

    PubMed

    Yoo, Barney; Ma, Kai; Zhang, Li; Burns, Andrew; Sequeira, Sonia; Mellinghoff, Ingo; Brennan, Cameron; Wiesner, Ulrich; Bradbury, Michelle S

    2015-11-15

    The physicochemical design and synthesis of effective cancer-directed and particle-based nanotherapeutic imaging agents remains a challenging task. Of critical importance is the ability to demonstrate maximum delivery, retention, and treatment efficacy for platforms designed to deposit their cargo at sites of disease without attendant dose-limiting toxicity. In this work, we describe dual-modality nanoparticle drug conjugates (NDCs) which utilize protease sensitive linkers to attached drug compounds and imaging labels to a clinically translated class of ultrasmall silica nanoparticle (C' dots). We describe the synthesis and characterization of these linker-drug constructs. Linkers incorporating dipeptide enzyme substrates are attached to analogs of a prototypical epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), through a cleavable amide bond or para-aminobenzyloxycarbonyl (PABC) group. These constructs are conjugated onto C' dots leading to the desired NDCs. These NDCs exhibit fast and predictable release kinetics in the presence of model proteases, and are stable in various biological media. Finally, in vitro assays show NDCs to be highly active in reducing phosphorylated EGFR levels in H1650 cells, a human tumor-derived cell line. The data suggests that NDCs exhibit desirable properties that warrant further development toward oncological therapy. PMID:26462054

  19. Determination of biodistribution of ultrasmall, near-infrared emitting gold nanoparticles by photoacoustic and fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Poon, Wilson; Heinmiller, Andrew; Zhang, Xuan; Nadeau, Jay L.

    2015-06-01

    This study compares fluorescence and photoacoustic (PA) imaging of ex vivo tumors and organs from tumor-bearing mice injected intravenously with ultrasmall (<3 nm) tiopronin-capped Au nanoparticles and compares the data with inductively coupled plasma mass spectrometry (ICP-MS). Good agreement is seen in particle distributions and concentrations at the organ level. The spatial resolution from the imaging techniques allows for localization of the particles within organ structures. Although the particles do not have a plasmon peak, their absorbance in the near-infrared (NIR) is sufficient for PA excitation. PA imaging shows an increase of signal as particle concentrations increase, with changes in spectrum if particles aggregate. Fluorescence imaging using the particles' native NIR emission shows agreement in general intensity in each organ, though quenching of emission can be seen at very high concentrations. Both of these imaging techniques are noninvasive and labor-saving alternatives to organ digestion and ICP-MS and may provide insight into cellular distribution of particles. The simple construct avoids the use of toxic semiconductor materials or dyes, relying upon the gold itself for both the fluorescence and PA signal. This provides a useful alternative to more complex approaches to multimodal imaging and one that is readily translatable to the clinic.

  20. Ligand-size dependent water proton relaxivities in ultrasmall gadolinium oxide nanoparticles and in vivo T1 MR images in a 1.5 T MR field.

    PubMed

    Kim, Cho Rong; Baeck, Jong Su; Chang, Yongmin; Bae, Ji Eun; Chae, Kwon Seok; Lee, Gang Ho

    2014-10-01

    The dependence of longitudinal (r1) and transverse (r2) water proton relaxivities of ultrasmall gadolinium oxide (Gd2O3) nanoparticles on the surface coating ligand-size was investigated. Both r1 and r2 values decreased with increasing ligand-size. We attributed this to the ligand-size effect. In addition the effectiveness of d-glucuronic acid-coated ultrasmall Gd2O3 nanoparticles as T1 magnetic resonance imaging (MRI) contrast agents was confirmed by measuring the in vitro cytotoxicity and using in vivo T1 MR images in a mouse in a 1.5 T MR field.

  1. Effects of the synthesis temperature on the crystalline structure and the magnetic properties of cobalt ferrite nanoparticles prepared via coprecipitation

    NASA Astrophysics Data System (ADS)

    Hutamaningtyas, Evangelin; Utari; Suharyana; Purnama, Budi; Wijayanta, Agung Tri

    2016-08-01

    The effects of the synthesis temperature on the crystalline structure and the magnetic properties of cobalt ferrite (CoFe2O4) nanoparticles prepared via coprecipitation are discussed. The synthesis was conducted at temperatures of 75 °C, 85 °C and 95 °C. Fourier transform infrared spectroscopy characterization related to a stretching vibration at a wavenumber of 590 cm-1 indicated the formation of a CoFe2O4 metal oxide. In addition, powder X ray diffraction (XRD) characterization proved that the metal oxide was CoFe2O4. Crystallite sizes calculated using the Scherer formula at the strongest peak of the XRD spectra of the samples synthesized at 75 °C, 85 °C and 95 °C were 32 nm, 43 nm and 50.4 nm, respectively. Finally, the results of the vibrating sample magnetometer characterization showed that the saturation magnetization decreased with increasing synthesis temperature, which is related to the dominant preference of Co2+ over Fe3+ cations at the octahedral sites.

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

    PubMed

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

    2011-09-01

    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.

  3. Non-Specific Zn2+ Ion Sensing Using Ultrasmall Gadolinium Oxide Nanoparticle as a Magnetic Resonance Imaging Contrast Agent.

    PubMed

    Bony, Badrul Alam; Baeck, Jong Su; Chang, Yongmin; Lee, Gang Ho

    2016-03-01

    The gadolinium oxide (Gd2O3) nanoparticles are well-known potential candidates for a positive magnetic resonance imaging (MRI) contrast agent owing to their large longitudinal water proton relaxivity (r1) value with r2/r1 ratio close to one (r2 = transverse water proton relaxivity). In addition they may be used to sense metal ions because their r1 and r2 values can be altered in the presence of metal ions. This may allow us to study metabolic processes involving metal ions and to diagnose disease related to abnormal concentrations of metal ions in the body in a non-invasive way. In this study ultrasmall Gd2O3 nanoparticles were for the first time applied to non-specifically sense Zn2+ ions in aqueous solution. We explored this by measuring r1 and r2 values in the presence of Zn2+ ions in solution.

  4. One-step synthesis of water-dispersible ultra-small Fe3O4 nanoparticles as contrast agents for T1 and T2 magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Wang, Guannan; Zhang, Xuanjun; Skallberg, Andreas; Liu, Yaxu; Hu, Zhangjun; Mei, Xifan; Uvdal, Kajsa

    2014-02-01

    Uniform, highly water-dispersible and ultra-small Fe3O4 nanoparticles were synthesized via a modified one-step coprecipitation approach. The prepared Fe3O4 nanoparticles not only show good magnetic properties, long-term stability in a biological environment, but also exhibit good biocompatibility in cell viability and hemolysis assay. Due to the ultra-small sized and highly water-dispersibility, they exhibit excellent relaxivity properties, the 1.7 nm sized Fe3O4 nanoparticles reveal a low r2/r1 ratio of 2.03 (r1 = 8.20 mM-1 s-1, r2 = 16.67 mM-1 s-1) and the 2.2 nm sized Fe3O4 nanoparticles also appear to have a low r2/r1 ratio of 4.65 (r1 = 6.15 mM-1 s-1, r2 = 28.62 mM-1 s-1). This demonstrates that the proposed ultra-small Fe3O4 nanoparticles have great potential as a new type of T1 magnetic resonance imaging contrast agents. Especially, the 2.2 nm sized Fe3O4 nanoparticles, have a competitive r1 value and r2 value compared to commercial contrasting agents such as Gd-DTPA (r1 = 4.8 mM-1 s -1), and SHU-555C (r2 = 69 mM-1 s-1). In vitro and in vivo imaging experiments, show that the 2.2 nm sized Fe3O4 nanoparticles exhibit great contrast enhancement, long-term circulation, and low toxicity, which enable these ultra-small sized Fe3O4 nanoparticles to be promising as T1 and T2 dual contrast agents in clinical settings.Uniform, highly water-dispersible and ultra-small Fe3O4 nanoparticles were synthesized via a modified one-step coprecipitation approach. The prepared Fe3O4 nanoparticles not only show good magnetic properties, long-term stability in a biological environment, but also exhibit good biocompatibility in cell viability and hemolysis assay. Due to the ultra-small sized and highly water-dispersibility, they exhibit excellent relaxivity properties, the 1.7 nm sized Fe3O4 nanoparticles reveal a low r2/r1 ratio of 2.03 (r1 = 8.20 mM-1 s-1, r2 = 16.67 mM-1 s-1) and the 2.2 nm sized Fe3O4 nanoparticles also appear to have a low r2/r1 ratio of 4.65 (r1 = 6.15 mM-1 s

  5. One-step synthesis of water-dispersible ultra-small Fe3O4 nanoparticles as contrast agents for T1 and T2 magnetic resonance imaging.

    PubMed

    Wang, Guannan; Zhang, Xuanjun; Skallberg, Andreas; Liu, Yaxu; Hu, Zhangjun; Mei, Xifan; Uvdal, Kajsa

    2014-03-01

    Uniform, highly water-dispersible and ultra-small Fe3O4 nanoparticles were synthesized via a modified one-step coprecipitation approach. The prepared Fe3O4 nanoparticles not only show good magnetic properties, long-term stability in a biological environment, but also exhibit good biocompatibility in cell viability and hemolysis assay. Due to the ultra-small sized and highly water-dispersibility, they exhibit excellent relaxivity properties, the 1.7 nm sized Fe3O4 nanoparticles reveal a low r2/r1 ratio of 2.03 (r1 = 8.20 mM(-1) s(-1), r2 = 16.67 mM(-1) s(-1)); and the 2.2 nm sized Fe3O4 nanoparticles also appear to have a low r2/r1 ratio of 4.65 (r1 = 6.15 mM(-1) s(-1), r2 = 28.62 mM(-1) s(-1)). This demonstrates that the proposed ultra-small Fe3O4 nanoparticles have great potential as a new type of T1 magnetic resonance imaging contrast agents. Especially, the 2.2 nm sized Fe3O4 nanoparticles, have a competitive r1 value and r2 value compared to commercial contrasting agents such as Gd-DTPA (r1 = 4.8 mM(-1) s (-1)), and SHU-555C (r2 = 69 mM(-1) s(-1)). In vitro and in vivo imaging experiments, show that the 2.2 nm sized Fe3O4 nanoparticles exhibit great contrast enhancement, long-term circulation, and low toxicity, which enable these ultra-small sized Fe3O4 nanoparticles to be promising as T1 and T2 dual contrast agents in clinical settings.

  6. Fabrication and evaluation of tumor-targeted positive MRI contrast agent based on ultrasmall MnO nanoparticles.

    PubMed

    Huang, Haitao; Yue, Tao; Xu, Ke; Golzarian, Jafar; Yu, Jiahui; Huang, Jin

    2015-07-01

    Gd(III) chelate is currently used as positive magnetic resonance imaging (MRI) contrast agent in clinical diagnosis, but generally induces the risk of nephrogenic systemic fibrosis (NSF) due to the dissociated Gd(3+) from Gd(III) chelates. To develop a novel positive MRI contrast agent with low toxicity and high sensitivity, ultrasmall MnO nanoparticles were PEGylated via catechol-Mn chelation and conjugated with cRGD as active targeting function to tumor. Particularly, the MnO nanoparticles with a size of ca. 5nm were modified by α,β-poly(aspartic acid)-based graft polymer containing PEG and DOPA moieties and, meanwhile, conjugated with cRGD to produce the contrast agent with a size of ca. 100nm and a longitudinal relaxivity (r1) of 10.2mM(-1)S(-1). Such nanoscaled contrast agent integrated passive- and active-targeting function to tumor, and its efficient accumulation behavior in tumor was verified by in vivo distribution study. At the same time, the PEG moiety played a role of hydrophilic coating to improve the biocompatibility and stability under storing and physiological conditions, and especially might guarantee enough circulation time in blood. Moreover, in vivo MRI revealed a good and long-term effect of enhancing MRI signal for as-fabricated contrast agent while cell viability assay proved its acceptable cytotoxicity for MRI application. On the whole, the as-fabricated PEGylated and cRGD-functionalized contrast agent based on ultrasmall MnO nanoparticles showed a great potential to the T1-weighted MRI diagnosis of tumor.

  7. Synergistic Effect between Ultra-Small Nickel Hydroxide Nanoparticles and Reduced Graphene Oxide sheets for the Application in High-Performance Asymmetric Supercapacitor

    PubMed Central

    Liu, Yonghuan; Wang, Rutao; Yan, Xingbin

    2015-01-01

    Nanoscale electrode materials including metal oxide nanoparticles and two-dimensional graphene have been employed for designing supercapacitors. However, inevitable agglomeration of nanoparticles and layers stacking of graphene largely hamper their practical applications. Here we demonstrate an efficient co-ordination and synergistic effect between ultra-small Ni(OH)2 nanoparticles and reduced graphene oxide (RGO) sheets for synthesizing ideal electrode materials. On one hand, to make the ultra-small Ni(OH)2 nanoparticles work at full capacity as an ideal pseudocapacitive material, RGO sheets are employed as an suitable substrate to anchor these nanoparticles against agglomeration. As a consequence, an ultrahigh specific capacitance of 1717 F g−1 at 0.5 A g−1 is achieved. On the other hand, to further facilitate ion transfer within RGO sheets as an ideal electrical double layer capacitor material, the ultra-small Ni(OH)2 nanoparticles are introduced among RGO sheets as the recyclable sacrificial spacer to prevent the stacking. The resulting RGO sheets exhibit superior rate capability with a high capacitance of 182 F g−1 at 100 A g−1. On this basis, an asymmetric supercapacitor is assembled using the two materials, delivering a superior energy density of 75 Wh kg−1 and an ultrahigh power density of 40 000 W kg−1. PMID:26053847

  8. Synergistic Effect between Ultra-Small Nickel Hydroxide Nanoparticles and Reduced Graphene Oxide sheets for the Application in High-Performance Asymmetric Supercapacitor

    NASA Astrophysics Data System (ADS)

    Liu, Yonghuan; Wang, Rutao; Yan, Xingbin

    2015-06-01

    Nanoscale electrode materials including metal oxide nanoparticles and two-dimensional graphene have been employed for designing supercapacitors. However, inevitable agglomeration of nanoparticles and layers stacking of graphene largely hamper their practical applications. Here we demonstrate an efficient co-ordination and synergistic effect between ultra-small Ni(OH)2 nanoparticles and reduced graphene oxide (RGO) sheets for synthesizing ideal electrode materials. On one hand, to make the ultra-small Ni(OH)2 nanoparticles work at full capacity as an ideal pseudocapacitive material, RGO sheets are employed as an suitable substrate to anchor these nanoparticles against agglomeration. As a consequence, an ultrahigh specific capacitance of 1717 F g-1 at 0.5 A g-1 is achieved. On the other hand, to further facilitate ion transfer within RGO sheets as an ideal electrical double layer capacitor material, the ultra-small Ni(OH)2 nanoparticles are introduced among RGO sheets as the recyclable sacrificial spacer to prevent the stacking. The resulting RGO sheets exhibit superior rate capability with a high capacitance of 182 F g-1 at 100 A g-1. On this basis, an asymmetric supercapacitor is assembled using the two materials, delivering a superior energy density of 75 Wh kg-1 and an ultrahigh power density of 40 000 W kg-1.

  9. Rapid microwave-assisted synthesis of PVP-coated ultrasmall gadolinium oxide nanoparticles for magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Vahdatkhah, Parisa; Madaah Hosseini, Hamid Reza; Khodaei, Azin; Montazerabadi, Ali Reza; Irajirad, Rasoul; Oghabian, Mohamad Ali; Delavari H., Hamid

    2015-05-01

    Synthesis of polyvinyl pyrrolidone (PVP) coated ultrasmall Gd2O3 nanoparticles (NPs) with enhanced T1-weighted signal intensity and r2/r1 ratio close to unity is performed by a microwave-assisted polyol process. PVP coated Gd2O3NPs with spherical shape and uniform size of 2.5 ± 0.5 nm have been synthesized below 5 min and structure and morphology confirmed by HRTEM, XRD and FTIR. The longitudinal (r1) and transversal relaxation (r2) of Gd2O3NPs is measured by a 3 T MRI scanner. The results showed considerable increasing of relaxivity for Gd2O3NPs in comparison to gadolinium chelates which are commonly used for clinical magnetic resonance imaging. In addition, a mechanism for Gd2O3NPs formation and in situ surface modification of PVP-grafted Gd2O3NPs is proposed.

  10. Ligand-size and ligand-chain hydrophilicity effects on the relaxometric properties of ultrasmall Gd2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Tegafaw, Tirusew; Xu, Wenlong; Lee, Sang Hyup; Chae, Kwon Seok; Cha, Hyunsil; Chang, Yongmin; Lee, Gang Ho

    2016-06-01

    The relaxometric properties of ultrasmall Gd2O3 nanoparticles coated with various ligands were investigated. These ligands include small diacids with hydrophobic chains, namely, succinic acid (Mw = 118.09 amu), glutaric acid (Mw = 132.12 amu), and terephthalic acid (Mw = 166.13 amu), and large polyethylenimines (PEIs) with hydrophilic chains, namely, PEI-1300 ( M ¯ n = 1300 ) and PEI-10000 ( M ¯ n = 10000 ). Ligand-size and ligand-chain hydrophilicity effects were observed. The longitudinal (r1) and transverse (r2) water proton relaxivities generally decreased with increasing ligand-size (the ligand-size effect). The ligand-size effect was weaker for PEI because its hydrophilic chains allow water molecules to access the nanoparticle (the ligand-chain hydrophilicity effect). This result was explained on the basis of the magnetic dipole interaction between the dipoles of the nanoparticle and water proton. In addition, all samples were found to be non-toxic in cellular cytotoxicity tests.

  11. Transfer of ultrasmall iron oxide nanoparticles from human brain-derived endothelial cells to human glioblastoma cells.

    PubMed

    Halamoda Kenzaoui, Blanka; Angeloni, Silvia; Overstolz, Thomas; Niedermann, Philippe; Chapuis Bernasconi, Catherine; Liley, Martha; Juillerat-Jeanneret, Lucienne

    2013-05-01

    Nanoparticles (NPs) are being used or explored for the development of biomedical applications in diagnosis and therapy, including imaging and drug delivery. Therefore, reliable tools are needed to study the behavior of NPs in biological environment, in particular the transport of NPs across biological barriers, including the blood-brain tumor barrier (BBTB), a challenging question. Previous studies have addressed the translocation of NPs of various compositions across cell layers, mostly using only one type of cells. Using a coculture model of the human BBTB, consisting in human cerebral endothelial cells preloaded with ultrasmall superparamagnetic iron oxide nanoparticles (USPIO NPs) and unloaded human glioblastoma cells grown on each side of newly developed ultrathin permeable silicon nitride supports as a model of the human BBTB, we demonstrate for the first time the transfer of USPIO NPs from human brain-derived endothelial cells to glioblastoma cells. The reduced thickness of the permeable mechanical support compares better than commercially available polymeric supports to the thickness of the basement membrane of the cerebral vascular system. These results are the first report supporting the possibility that USPIO NPs could be directly transferred from endothelial cells to glioblastoma cells across a BBTB. Thus, the use of such ultrathin porous supports provides a new in vitro approach to study the delivery of nanotherapeutics to brain cancers. Our results also suggest a novel possibility for nanoparticles to deliver therapeutics to the brain using endothelial to neural cells transfer.

  12. Ultrasmall integrin-targeted silica nanoparticles modulate signaling events and cellular processes in a concentration-dependent manner.

    PubMed

    Benezra, Miriam; Phillips, Evan; Overholtzer, Michael; Zanzonico, Pat B; Tuominen, Esa; Wiesner, Ulrich; Bradbury, Michelle S

    2015-04-01

    Cellular and molecular-level interactions of nanoparticles with biological systems are a rapidly evolving field requiring an improved understanding of endocytic trafficking as the principal driver and regulator of signaling events and cellular responses. An understanding of these processes is vital to nanomedicine applications. Studies investigating the complex interplay of these processes and their relationship to targeted nanoparticles exploiting endocytic pathways are notably lacking. It is known that integrins traffic through the endosomal pathway and participate in diverse roles controlling signal transduction, cell migration, and proliferation. Here, it is shown that ultrasmall, nontoxic, core-shell silica nanoparticles (C-dots), surface-functionalized with cRGDY peptides, modestly activate integrin-signaling pathways, in turn, promoting the enhancement of cellular functions. First, nanomolar concentrations, two orders of magnitude higher than clinical trial doses, internalize within αvβ3 integrin-expressing melanoma and endothelial cells, predominantly through an integrin receptor-dependent endocytic route. Second, integrin-mediated activation of focal adhesion kinase (FAK) and downstream signaling pathways occurs, in turn, upregulating phosphorylated protein expression levels and promoting concentration-dependent cellular migration and proliferative activity. Inhibiting FAK catalytic activity leads to decreased phosphorylation levels and cellular migration rates. These findings may inform the design of more effectively-targeted nanomedicines and provide insights into endocytic regulation of signal transduction.

  13. Ultra-small Fe3O4 nanoparticle decorated graphene nanosheets with superior cyclic performance and rate capability

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Song, Bohang; Lu, Li; Xue, Junmin

    2013-07-01

    Advanced anode materials for next generation lithium ion batteries have attracted great interest due to the ever increasing demand for powerful, light-weight, and compact electrical devices. In this work, graphene nanosheets decorated with ultra-small Fe3O4 nanoparticles (USIO/G) were synthesized via a facile hydrothermal method. Compared with other reported Fe3O4-based anode composites, USIO/G demonstrated superior cyclic ability and excellent rate capability owing to its ultra-small size of active lithium storage sites, Fe3O4, with an average diameter less than 5 nm. Furthermore, graphene nanosheets played an important role in the overall electrochemical performance of the composite by enhancing the electrical conductivity, forming a flexible network, and providing extra lithium storage sites. The obtained composites were tested for electrochemical performance for a total number of 2120 cycles: a rate capability test with current densities ranged from 90 to 7200 mA g-1 for 920 cycles, followed by a cycling test at 1800 mA g-1 for 1200 cycles. For the rate capability test, steady reversible capacities were delivered under each current density with final reversible capacities of 1177, 1096, 833, 488, 242, and 146 mA h g-1 at 90, 180, 900, 1800, 3600, and 7200 mA g-1, respectively. The subsequent cyclic test demonstrated the superior cyclic stability of USIO/G and a reversible capacity of 437 mA h g-1 at the 2120th cycle was delivered.Advanced anode materials for next generation lithium ion batteries have attracted great interest due to the ever increasing demand for powerful, light-weight, and compact electrical devices. In this work, graphene nanosheets decorated with ultra-small Fe3O4 nanoparticles (USIO/G) were synthesized via a facile hydrothermal method. Compared with other reported Fe3O4-based anode composites, USIO/G demonstrated superior cyclic ability and excellent rate capability owing to its ultra-small size of active lithium storage sites, Fe3O4, with

  14. Synthesis, Characterization, and X-ray Attenuation Properties of Ultrasmall BiOI Nanoparticles: Toward Renal Clearable Particulate CT Contrast Agents

    PubMed Central

    2015-01-01

    A unique decelerated hydrolytic procedure is developed and reported here for the preparation of ultrasmall nanoparticles (NPs) of PVP-coated BiOI with a narrow size distribution, i.e., 2.8 ± 0.5 nm. The crystal structure of this compound is determined by X-ray powder diffraction using the bulk materials. The stability, cytotoxicity, and potential use of the PVP-coated ultrasmall BiOI NPs as a CT contrast agent are investigated. Because of the combined X-ray attenuation effect of bismuth and iodine, such NPs exhibit a CT value that is among the best of those of the inorganic nanoparticle-based CT contrast agents reported in the literature. PMID:25283335

  15. Magnoelastic coupling in magnetic oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Sun, Qi; Baker, Sheila; Birkel, Christina; Seshadri, Ram; Tremel, Wolfgang; Christianson, Andrew; Musfeldt, Janice

    2012-02-01

    Phonons are exquisitely sensitive to finite length scale effects in a wide variety of materials. To investigate confinement in combination with strong magnetoelastic interactions, we measured the infrared vibrational properties of MnO and CoFe2O4 nanoparticles and their parent compounds. For MnO, a charge and bonding analysis reveals that Born effective charge, local effective charge, total polarizability, and the force constant are overall lower in the nanoparticles compared to the bulk. We find that the spin-lattice coupling drops from ˜7 cm-1 in the single crystal to <1 cm-1 in the nanoparticles. For CoFe2O4, the spectroscopic response is sensitive to the size-induced crossover to the superparamagnetic state, which occurs between 7 and 10 nm, and a spin-phonon coupling analysis supports the core-shell model. Moreover, it provides an estimate of the thickness of the magnetically disordered shell, increasing from 0.4 nm in the 14 nm particles to 0.8 nm in the 5 nm particles, demonstrating that the associated local lattice distortions take place on the length scale of the unit cell. These findings are important for understanding finite length scale effects in magnetic oxides and other more complex functional oxides.

  16. A top-down synthesis route to ultrasmall multifunctional Gd-based silica nanoparticles for theranostic applications.

    PubMed

    Mignot, Anna; Truillet, Charles; Lux, François; Sancey, Lucie; Louis, Cédric; Denat, Franck; Boschetti, Frédéric; Bocher, Laura; Gloter, Alexandre; Stéphan, Odile; Antoine, Rodolphe; Dugourd, Philippe; Luneau, Dominique; Novitchi, Ghenadie; Figueiredo, Leandro Carlos; de Morais, Paulo Cesar; Bonneviot, Laurent; Albela, Belen; Ribot, François; Van Lokeren, Luk; Déchamps-Olivier, Isabelle; Chuburu, Françoise; Lemercier, Gilles; Villiers, Christian; Marche, Patrice N; Le Duc, Géraldine; Roux, Stéphane; Tillement, Olivier; Perriat, Pascal

    2013-05-01

    New, ultrasmall nanoparticles with sizes below 5 nm have been obtained. These small rigid platforms (SRP) are composed of a polysiloxane matrix with DOTAGA (1,4,7,10-tetraazacyclododecane-1-glutaric anhydride-4,7,10-triacetic acid)-Gd(3+) chelates on their surface. They have been synthesised by an original top-down process: 1) formation of a gadolinium oxide Gd2O3 core, 2) encapsulation in a polysiloxane shell grafted with DOTAGA ligands, 3) dissolution of the gadolinium oxide core due to chelation of Gd(3+) by DOTAGA ligands and 4) polysiloxane fragmentation. These nanoparticles have been fully characterised using photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), a superconducting quantum interference device (SQUID) and electron paramagnetic resonance (EPR) to demonstrate the dissolution of the oxide core and by inductively coupled plasma mass spectrometry (ICP-MS), mass spectrometry, fluorescence spectroscopy, (29)Si solid-state NMR, (1)H NMR and diffusion ordered spectroscopy (DOSY) to determine the nanoparticle composition. Relaxivity measurements gave a longitudinal relaxivity r1 of 11.9 s(-1)  mM(-1) per Gd at 60 MHz. Finally, potentiometric titrations showed that Gd(3+) is strongly chelated to DOTAGA (complexation constant logβ110 =24.78) and cellular tests confirmed the that nanoconstructs had a very low toxicity. Moreover, SRPs are excreted from the body by renal clearance. Their efficiency as contrast agents for MRI has been proved and they are promising candidates as sensitising agents for image-guided radiotherapy.

  17. Fabrication of Efficient Hydrogenation Nanoreactors by Modifying the Freedom of Ultrasmall Platinum Nanoparticles within Yolk-Shell Nanospheres.

    PubMed

    Peng, Juan; Lan, Guojun; Guo, Miao; Wei, Xuming; Li, Can; Yang, Qihua

    2015-07-13

    The synthesis of silica-based yolk-shell nanospheres confined with ultrasmall platinum nanoparticles (Pt NPs) stabilized with poly(amidoamine), in which the interaction strength between Pt NPs and the support could be facilely tuned, is reported. By ingenious utilization of silica cores with different surface wettability (hydrophilic vs. -phobic) as the adsorbent, Pt NPs could be confined in different locations of the yolk-shell nanoreactor (core vs. hollow shell), and thus, exhibit different interaction strengths with the nanoreactor (strong vs. weak). It is interesting to find that the adsorbed Pt NPs are released from the core to the hollow interiors of the yolk-shell nanospheres when a superhydrophobic inner core material (SiO2 -Ph) is employed, which results in the preparation of an immobilized catalyst (Pt@SiO2-Ph); this possesses the weakest interaction strength with the support and shows the highest catalytic activity (88 500 and 7080 h(-1) for the hydrogenation of cyclohexene and nitrobenzene, respectively), due to its unaffected freedom of Pt NPs for retention of the intrinsic properties.

  18. Tuning the magnetism of ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Viñas, S. Liébana; Simeonidis, K.; Li, Z.-A.; Ma, Z.; Myrovali, E.; Makridis, A.; Sakellari, D.; Angelakeris, M.; Wiedwald, U.; Spasova, M.; Farle, M.

    2016-10-01

    The importance of magnetic interactions within an individual nanoparticle or between adjacent ones is crucial not only for the macroscopic collective magnetic behavior but for the AC magnetic heating efficiency as well. On this concept, single-(MFe2O4 where M=Fe, Co, Mn) and core-shell ferrite nanoparticles consisting of a magnetically softer (MnFe2O4) or magnetically harder (CoFe2O4) core and a magnetite (Fe3O4) shell with an overall size in the 10 nm range were synthesized and studied for their magnetic particle hyperthermia efficiency. Magnetic measurements indicate that the coating of the hard magnetic phase (CoFe2O4) by Fe3O4 provides a significant enhancement of hysteresis losses over the corresponding single-phase counterpart response, and thus results in a multiplication of the magnetic hyperthermia efficiency opening a novel pathway for high-performance, magnetic hyperthermia agents. At the same time, the existence of a biocompatible Fe3O4 outer shell, toxicologically renders these systems similar to iron-oxide ones with significantly milder side-effects.

  19. Synthesis of ultra-small cysteine-capped gold nanoparticles by pH switching of the Au(I)-cysteine polymer.

    PubMed

    Cappellari, Paula S; Buceta, David; Morales, Gustavo M; Barbero, Cesar A; Sergio Moreno, M; Giovanetti, Lisandro J; Ramallo-López, José Martín; Requejo, Felix G; Craievich, Aldo F; Planes, Gabriel A

    2015-03-01

    We report a synthetic approach for the production of ultra-small (0.6 nm) gold nanoparticles soluble in water with a precise control of the nanoparticle size. Our synthetic approach utilizes a pH-depending Au-cysteine polymer as a quencher for the AuNPs grown. The method extends the synthetic capabilities of nanoparticles with sizes down to 1 nm. In addition to the strict pH control, the existence of free -SH groups present in the mixture of reaction has been observed as a key requirement for the synthesis of small nanoparticles in mild conditions. UV-Vis, SAXS, XANES, EXAFS and HR-TEM, has been used to determinate the particle size, characterization of the gold precursor and gold-cysteine interaction.

  20. Synthesis of magnetic cobalt ferrite nanoparticles with controlled morphology, monodispersity and composition: the influence of solvent, surfactant, reductant and synthetic conditions

    NASA Astrophysics Data System (ADS)

    Lu, Le T.; Dung, Ngo T.; Tung, Le D.; Thanh, Cao T.; Quy, Ong K.; Chuc, Nguyen V.; Maenosono, Shinya; Thanh, Nguyen T. K.

    2015-11-01

    In our present work, magnetic cobalt ferrite (CoFe2O4) nanoparticles have been successfully synthesised by thermal decomposition of Fe(iii) and Co(ii) acetylacetonate compounds in organic solvents in the presence of oleic acid (OA)/ oleylamine (OLA) as surfactants and 1,2-hexadecanediol (HDD) or octadecanol (OCD-ol) as an accelerating agent. As a result, CoFe2O4 nanoparticles of different shapes were tightly controlled in size (range of 4-30 nm) and monodispersity (standard deviation only at ca. 5%). Experimental parameters, such as reaction time, temperature, surfactant concentration, solvent, precursor ratio, and accelerating agent, in particular, the role of HDD, OCD-ol, and OA/OLA have been intensively investigated in detail to discover the best conditions for the synthesis of the above magnetic nanoparticles. The obtained nanoparticles have been successfully applied for producing oriented carbon nanotubes (CNTs), and they have potential to be used in biomedical applications.In our present work, magnetic cobalt ferrite (CoFe2O4) nanoparticles have been successfully synthesised by thermal decomposition of Fe(iii) and Co(ii) acetylacetonate compounds in organic solvents in the presence of oleic acid (OA)/ oleylamine (OLA) as surfactants and 1,2-hexadecanediol (HDD) or octadecanol (OCD-ol) as an accelerating agent. As a result, CoFe2O4 nanoparticles of different shapes were tightly controlled in size (range of 4-30 nm) and monodispersity (standard deviation only at ca. 5%). Experimental parameters, such as reaction time, temperature, surfactant concentration, solvent, precursor ratio, and accelerating agent, in particular, the role of HDD, OCD-ol, and OA/OLA have been intensively investigated in detail to discover the best conditions for the synthesis of the above magnetic nanoparticles. The obtained nanoparticles have been successfully applied for producing oriented carbon nanotubes (CNTs), and they have potential to be used in biomedical applications. Electronic

  1. Synthesis of ultrasmall magnetic iron oxide nanoparticles and study of their colloid and surface chemistry

    NASA Astrophysics Data System (ADS)

    Goloverda, Galina; Jackson, Barry; Kidd, Clayton; Kolesnichenko, Vladimir

    2009-05-01

    Colloidal nanoparticles of Fe 3O 4 (4 nm) were synthesized by high-temperature hydrolysis of chelated iron (II) and (III) diethylene glycol alkoxide complexes in a solution of the parent alcohol (H 2DEG) without using capping ligands or surfactants: [Fe(DEG)Cl 2] 2-+2[Fe(DEG)Cl 3] 2-+2H 2O+2OH -→Fe 3O 4+3H 2DEG+8Cl - The obtained particles were reacted with different small-molecule polydentate ligands, and the resulting adducts were tested for aqueous colloid formation. Both the carboxyl and α-hydroxyl groups of the hydroxyacids are involved in coordination to the nanoparticles' surface. This coordination provides the major contribution to the stability of the ligand-coated nanoparticles against hydrolysis.

  2. Differential stress reaction of human colon cells to oleic-acid-stabilized and unstabilized ultrasmall iron oxide nanoparticles.

    PubMed

    Schütz, Catherine A; Staedler, Davide; Crosbie-Staunton, Kieran; Movia, Dania; Chapuis Bernasconi, Catherine; Kenzaoui, Blanka Halamoda; Prina-Mello, Adriele; Juillerat-Jeanneret, Lucienne

    2014-01-01

    Therapeutic engineered nanoparticles (NPs), including ultrasmall superparamagnetic iron oxide (USPIO) NPs, may accumulate in the lower digestive tract following ingestion or injection. In order to evaluate the reaction of human colon cells to USPIO NPs, the effects of non-stabilized USPIO NPs (NS-USPIO NPs), oleic-acid-stabilized USPIO NPs (OA-USPIO NPs), and free oleic acid (OA) were compared in human HT29 and CaCo2 colon epithelial cancer cells. First the biophysical characteristics of NS-USPIO NPs and OA-USPIO NPs in water, in cell culture medium supplemented with fetal calf serum, and in cell culture medium preconditioned by HT29 and CaCo₂ cells were determined. Then, stress responses of the cells were evaluated following exposure to NS-USPIO NPs, OA-USPIO NPs, and free OA. No modification of the cytoskeletal actin network was observed. Cell response to stress, including markers of apoptosis and DNA repair, oxidative stress and degradative/autophagic stress, induction of heat shock protein, or lipid metabolism was determined in cells exposed to the two NPs. Induction of an autophagic response was observed in the two cell lines for both NPs but not free OA, while the other stress responses were cell- and NP-specific. The formation of lipid vacuoles/droplets was demonstrated in HT29 and CaCo₂ cells exposed to OA-USPIO NPs but not to NS-USPIO NPs, and to a much lower level in cells exposed to equimolar concentrations of free OA. Therefore, the induction of lipid vacuoles in colon cells exposed to OA utilized as a stabilizer for USPIO NPs is higly amplified compared to free OA, and is not observed in the absence of this lipid in NS-USPIO NPs. PMID:25092978

  3. Ultra-small rhenium nanoparticles immobilized on DNA scaffolds: An excellent material for surface enhanced Raman scattering and catalysis studies.

    PubMed

    Anantharaj, S; Sakthikumar, K; Elangovan, Ayyapan; Ravi, G; Karthik, T; Kundu, Subrata

    2016-12-01

    Highly Sensitive and ultra-small Rhenium (Re) metal nanoparticles (NPs) were successfully stabilized in water by the staging and fencing action of the versatile biomolecule DNA that resulted in two distinct aggregated chain-like morphologies with average grain sizes of 1.1±0.1nm and 0.7±0.1nm for the very first time within a minute of reaction time. Re NPs are formed by the borohydride reduction of ammonium perrhenate (NH4ReO4) in the presence of DNA at room temperature (RT) under stirring. The morphologies were controlled by carefully monitoring the molar ratio of NH4ReO4 and DNA. The synthesized material was employed in two potential applications: as a substrate for surface enhanced Raman scattering (SERS) studies and as a catalyst for the reduction of aromatic nitro compounds. SERS study was carried out by taking methylene blue (MB) as the probe and the highest SERS enhancement factor (EF) of 2.07×10(7) was found for the aggregated chain-like having average grain size of 0.7±0.1nm. Catalytic reduction of 4-nitro phenol (4-NP), 2-nitro phenol (2-NP) and 4-nitroaniline (4-NA) with a rate constant value of 6×10(-2)min(-1), 33.83×10(-2)min(-1) and 37.4×10(-2)min(-1) have testified the excellent catalytic performance of our Re NPs immobilized on DNA. The overall study have revealed the capability of DNA in stabilizing the highly reactive Re metal at nanoscale and made them applicable in practice. The present route can also be extended to prepare one dimensional (1-D), self-assembled NPs of other reactive metals, mixed metals or even metal oxides for specific applications in water based solutions. PMID:27571687

  4. Ultra-small lipid nanoparticles promote the penetration of coenzyme Q10 in skin cells and counteract oxidative stress.

    PubMed

    Lohan, Silke B; Bauersachs, Sonja; Ahlberg, Sebastian; Baisaeng, Nuttakorn; Keck, Cornelia M; Müller, Rainer H; Witte, Ellen; Wolk, Kerstin; Hackbarth, Steffen; Röder, Beate; Lademann, Jürgen; Meinke, Martina C

    2015-01-01

    UV irradiation leads to the formation of reactive oxygen species (ROS). An imbalance between the antioxidant system and ROS can lead to cell damage, premature skin aging or skin cancer. To counteract these processes, antioxidants such as coenzyme Q10 (CoQ10) are contained in many cosmetics. To improve and optimize cell/tissue penetration properties of the lipophilic CoQ10, ultra-small lipid nanoparticles (usNLC) were developed. The antioxidant effectiveness of CoQ10-loaded usNLC compared to conventional nanocarriers was investigated in the human keratinocyte cell line HaCaT. Using confocal laser scanning microscopy investigations of the carriers additionally loaded with nile red showed a clear uptake into cells and their distribution within the cytoplasm. By use of the XTT cell viability test, CoQ10 concentrations of 10-50 μg/ml were shown to be non-toxic, and the antioxidant potential of 10 μg/ml CoQ10 loaded usNLC in the HaCaT cells was analyzed via electron paramagnetic resonance spectroscopy after cellular exposure to UVA (1J/cm(2)) and UVB (18 mJ/cm(2)) irradiation. In comparison with the CoQ10-loaded conventional carriers, usNLC-CoQ10 demonstrated the strongest reduction of the radical formation; reaching up to 23% compared to control cells without nanocarrier treatment. Therefore, usNLC-CoQ10 are very suitable to increase the antioxidant potential of skin.

  5. Structure investigation of ultra-small CdSe nanoparticles using the atomic PDF

    NASA Astrophysics Data System (ADS)

    Masadeh, Ahmad S.; Billinge, Simon J. L.; Bozin, Emil S.; McBride, James R.; Rosenthal, Sandra J.

    2011-03-01

    The size-dependent structure of CdSe nanoparticles, with diameter ranging from 1.5 to 3.6 nm, has been studied using the atomic pair distribution function (PDF) method. The samples are prepared by the methods of Peng et al, with modifications. The structure of the smallest stable size, (~ 1.5 nm), have been found to posses locally distorted wurtzite structure, with no clear evidence of a heavily disordered surface region. The PDF data of the smallest particle show an extra structural peak appears around r = 3.5 A indicates there is structure modification happened in this sample. This peak start appearing the nanoparticles PDF data gradually as nanoparticle size decreases. The structural parameters are reported quantitatively. We measure a size-dependent strain on the Cd-Se bond which reaches 1.0% at the smallest particle size. The size of the well-ordered core extracted directly from the data agrees with the size determined from other methods.

  6. Controllable synthesis of gold nanoparticles with ultrasmall size and high monodispersity via continuous supplement of precursor.

    PubMed

    Li, Yuanyuan; Liu, Shoujie; Yao, Tao; Sun, Zhihu; Jiang, Zheng; Huang, Yuying; Cheng, Hao; Huang, Yuanyuan; Jiang, Yong; Xie, Zhi; Pan, Guoqiang; Yan, Wensheng; Wei, Shiqiang

    2012-10-14

    Synthesis of monodisperse small Au nanoparticles in a controllable manner is of great importance for fundamental science and technical applications. Here, we report a "precursor continuous-supply" strategy for controllable synthesis of 0.9-3.3 nm Au nanoparticles with a narrow size distribution of 0.1-0.2 nm, using a weak reductant to slow-down the reducing rate of AuClPPh(3) precursor in ethanol. Time-dependent X-ray absorption and UV-Vis absorption measurements revealed that owing to the joint use of AuClPPh(3) and ethanol, the remnant AuClPPh(3) was self-supplied and the precursor concentration was maintained at a level near to its equilibrium solubility (ca. 1.65 mmol L(-1)) in ethanol. Hence the nucleation duration was extended that focused the initial size distribution of the Au clusters. With reaction going on for 58 min, most of AuClPPh(3) with a nominal Au concentration of 17.86 mmol L(-1) was converted to ethanol-soluble Au clusters with a size of about 1.0 nm, resulting in a high-yield synthesis.

  7. Paramagnetic ultrasmall gadolinium oxide nanoparticles as advanced T1 MRI contrast agent: account for large longitudinal relaxivity, optimal particle diameter, and in vivo T1 MR images.

    PubMed

    Park, Ja Young; Baek, Myung Ju; Choi, Eun Sook; Woo, Seungtae; Kim, Joo Hyun; Kim, Tae Jeong; Jung, Jae Chang; Chae, Kwon Seok; Chang, Yongmin; Lee, Gang Ho

    2009-11-24

    Paramagnetic ultrasmall gadolinium oxide (Gd(2)O(3)) nanoparticles with particle diameters (d) of approximately 1 nm were synthesized by using three kinds of Gd(III) ion precursors and by refluxing each of them in tripropylene glycol under an O(2) flow. A large longitudinal relaxivity (r(1)) of water proton of 9.9 s(-1) mM(-1) was estimated. As a result, high contrast in vivo T(1) MR images of the brain tumor of a rat were observed. This large r(1) is discussed in terms of the huge surface to volume ratio (S/V) of the ultrasmall gadolinium oxide nanoparticles coupled with the cooperative induction of surface Gd(III) ions for the longitudinal relaxation of a water proton. It is found from the d dependence of r(1) that the optimal range of d for the maximal r(1), which may be used as an advanced T(1) MRI contrast agent, is 1-2.5 nm.

  8. Iridium ultrasmall nanoparticles, worm-like chain nanowires, and porous nanodendrites: One-pot solvothermal synthesis and catalytic CO oxidation activity

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Li, Shuai-Chen; Zhu, Wei; Ke, Jun; Yu, Jing-Wen; Zhang, Zhi-Ping; Dai, Lin-Xiu; Gu, Jun; Zhang, Ya-Wen

    2016-06-01

    We report a facile one-pot solvothermal synthesis of monodisperse iridium (Ir) ultrasmall (1.5-2.5 nm in diameter) nanoparticles (NPs), worm-like chain nanowires (NWs), and porous nanodendrites (NDs), for which CO oxidation reaction has been employed as a probe reaction to investigate the effects of nanoparticle size and surface-capping organics on the catalytic activities. Time-dependent experiments revealed that an oriented attachment mechanism induced by the strong adsorption of halide anions (Br- and I-) on specific facet of Ir nanoclusters or by decreasing the reduction rate of Ir precursors with changing their concentrations during the synthesis was responsible for the formation of Ir NWs and NDs. Annealing tests indicated that an O2-H2 atmosphere treatment turned out to be an effective measure to clean up the surface-capping organics of Ir NPs supported on commercial SiO2. Catalytic CO oxidation reaction illustrated that a significant improvement in the catalytic activity of CO oxidation reaction was achieved together with the changing of activation energies after such atmosphere treatment for the supported catalysts of the ultrasmall Ir NPs. It is noteworthy that this enhancement in catalytic activity could be ascribed to the changes in the surface status (including populations of Ir species in metallic and oxidized states, removal of surface capping organics, the variety of active sites, and total effective active site number) for the supported nanocatalysts during the atmosphere treatment.

  9. Dual-mode T1 and T2 magnetic resonance imaging contrast agent based on ultrasmall mixed gadolinium-dysprosium oxide nanoparticles: synthesis, characterization, and in vivo application

    NASA Astrophysics Data System (ADS)

    Tegafaw, Tirusew; Xu, Wenlong; Wasi Ahmad, Md; Baeck, Jong Su; Chang, Yongmin; Bae, Ji Eun; Chae, Kwon Seok; Kim, Tae Jeong; Lee, Gang Ho

    2015-09-01

    A new type of dual-mode T1 and T2 magnetic resonance imaging (MRI) contrast agent based on mixed lanthanide oxide nanoparticles was synthesized. Gd3+ (8S7/2) plays an important role in T1 MRI contrast agents because of its large electron spin magnetic moment resulting from its seven unpaired 4f-electrons, and Dy3+ (6H15/2) has the potential to be used in T2 MRI contrast agents because of its very large total electron magnetic moment: among lanthanide oxide nanoparticles, Dy2O3 nanoparticles have the largest magnetic moments at room temperature. Using these properties of Gd3+ and Dy3+ and their oxide nanoparticles, ultrasmall mixed gadolinium-dysprosium oxide (GDO) nanoparticles were synthesized and their potential to act as a dual-mode T1 and T2 MRI contrast agent was investigated in vitro and in vivo. The D-glucuronic acid coated GDO nanoparticles (davg = 1.0 nm) showed large r1 and r2 values (r2/r1 ≈ 6.6) and as a result clear dose-dependent contrast enhancements in R1 and R2 map images. Finally, the dual-mode imaging capability of the nanoparticles was confirmed by obtaining in vivo T1 and T2 MR images.

  10. Dual-mode T1 and T2 magnetic resonance imaging contrast agent based on ultrasmall mixed gadolinium-dysprosium oxide nanoparticles: synthesis, characterization, and in vivo application.

    PubMed

    Tegafaw, Tirusew; Xu, Wenlong; Ahmad, Md Wasi; Baeck, Jong Su; Chang, Yongmin; Bae, Ji Eun; Chae, Kwon Seok; Kim, Tae Jeong; Lee, Gang Ho

    2015-09-11

    A new type of dual-mode T1 and T2 magnetic resonance imaging (MRI) contrast agent based on mixed lanthanide oxide nanoparticles was synthesized. Gd(3+) ((8)S7/2) plays an important role in T1 MRI contrast agents because of its large electron spin magnetic moment resulting from its seven unpaired 4f-electrons, and Dy(3+) ((6)H15/2) has the potential to be used in T2 MRI contrast agents because of its very large total electron magnetic moment: among lanthanide oxide nanoparticles, Dy2O3 nanoparticles have the largest magnetic moments at room temperature. Using these properties of Gd(3+) and Dy(3+) and their oxide nanoparticles, ultrasmall mixed gadolinium-dysprosium oxide (GDO) nanoparticles were synthesized and their potential to act as a dual-mode T1 and T2 MRI contrast agent was investigated in vitro and in vivo. The D-glucuronic acid coated GDO nanoparticles (davg = 1.0 nm) showed large r1 and r2 values (r2/r1 ≈ 6.6) and as a result clear dose-dependent contrast enhancements in R1 and R2 map images. Finally, the dual-mode imaging capability of the nanoparticles was confirmed by obtaining in vivo T1 and T2 MR images.

  11. Dual-mode T1 and T2 magnetic resonance imaging contrast agent based on ultrasmall mixed gadolinium-dysprosium oxide nanoparticles: synthesis, characterization, and in vivo application.

    PubMed

    Tegafaw, Tirusew; Xu, Wenlong; Ahmad, Md Wasi; Baeck, Jong Su; Chang, Yongmin; Bae, Ji Eun; Chae, Kwon Seok; Kim, Tae Jeong; Lee, Gang Ho

    2015-09-11

    A new type of dual-mode T1 and T2 magnetic resonance imaging (MRI) contrast agent based on mixed lanthanide oxide nanoparticles was synthesized. Gd(3+) ((8)S7/2) plays an important role in T1 MRI contrast agents because of its large electron spin magnetic moment resulting from its seven unpaired 4f-electrons, and Dy(3+) ((6)H15/2) has the potential to be used in T2 MRI contrast agents because of its very large total electron magnetic moment: among lanthanide oxide nanoparticles, Dy2O3 nanoparticles have the largest magnetic moments at room temperature. Using these properties of Gd(3+) and Dy(3+) and their oxide nanoparticles, ultrasmall mixed gadolinium-dysprosium oxide (GDO) nanoparticles were synthesized and their potential to act as a dual-mode T1 and T2 MRI contrast agent was investigated in vitro and in vivo. The D-glucuronic acid coated GDO nanoparticles (davg = 1.0 nm) showed large r1 and r2 values (r2/r1 ≈ 6.6) and as a result clear dose-dependent contrast enhancements in R1 and R2 map images. Finally, the dual-mode imaging capability of the nanoparticles was confirmed by obtaining in vivo T1 and T2 MR images. PMID:26291827

  12. Maghemite decorated with ultra-small palladium nanoparticles (γ-Fe2O3–Pd): applications in the Heck–Mizoroki olefination, Suzuki reaction and allylic oxidation of alkenes

    EPA Science Inventory

    A nanocatalyst comprising ultra-small Pd/PdO nanoparticles (<5 nm) supported on maghemite was prepared by a co-precipitation protocol using inexpensive raw materials and was deployed successfully in various significant synthetic transformations, namely the Heck–Mizoroki olefinati...

  13. 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

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

    2012-08-01

    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

  14. Nanophased CoFe 2O 4 prepared by combustion method

    NASA Astrophysics Data System (ADS)

    Yan, C.-H.; Xu, Z.-G.; Cheng, F.-X.; Wang, Z.-M.; Sun, L.-D.; Liao, C.-S.; Jia, J.-T.

    1999-07-01

    The combustion method has been utilized to prepare nanophased powders of cobalt spinel ferrite using glycine as fuel. Structural and magnetic properties of the products were investigated with an X-ray diffractometer, a surface analyzer, and an alternating gradient magnetometer, respectively. Cobalt spinel ferrite prepared by the present method can easily form the well-crystallized nanoscale particles with a large specific surface area. The magnetization and coercivity show a strong dependence on the G/N (glycine to nitrates) ratio in the range from 0.2 to 1.0.

  15. Ultrasmall Organic Nanoparticles with Aggregation-Induced Emission and Enhanced Quantum Yield for Fluorescence Cell Imaging.

    PubMed

    Xu, Suying; Bai, Xilin; Ma, Jingwen; Xu, Minmin; Hu, Gaofei; James, Tony D; Wang, Leyu

    2016-08-01

    The use of fluorescence probes for biomedical imaging has attracted significant attention over recent years owing to their high resolution at cellular level. The probes are available in many formats including small particle size based imaging agents which are considered to be promising candidates, due to their excellent stabilities. Yet, concerns over the potential cytotoxicity effects of inorganic luminescent particles have led to questions about their suitability for imaging applications. Exploration of alternatives inspired us to use organic fluorophores with aggregation-induced emission (AIE), prepared by functionalizing the amine group on tetraphenylethene with 3,5-bis(trifluoromethyl)phenyl isocyanate. The as-synthesized novel AIE fluorophore (TPE-F) display enhanced quantum yield and longer lifetime as compared with its counterparts (4,4',4″,4‴-(ethene-1,1,2,2-tetrayl)tetraaniline, TPE-AM). Furthermore, the TPE-F was encapsulated into small-size organic nanoparticles (NPs; dynamic light scattering size, ∼10 nm) with polysuccinimide (PSI). The biocompatibility, excellent stability, bright fluorescence, and selective cell targeting of these NPs enable the as-prepared TPE-F NPs to be suitable for specific fluorescence cell imaging. PMID:27349933

  16. Enhancing the antimicrobial activity of natural extraction using the synthetic ultrasmall metal nanoparticles

    PubMed Central

    Li, Huanhuan; Chen, Quansheng; Zhao, Jiewen; Urmila, Khulal

    2015-01-01

    The use of Catechin as an antibacterial agent is becoming ever-more common, whereas unstable and easy oxidation, have limited its application. A simple and low-energy-consuming approach to synthesize highly stable and dispersive Catechin-Cu nanoparticles(NPs) has been developed, in which the stability and dispersivity of the NPs are varied greatly with the pH value and temperature of the reaction. The results demonstrate that the optimal reaction conditions are pH 11 at room temperature. As-synthesized NPs display excellent antimicrobial activity, the survival rates of bacterial cells exposed to the NPs were evaluated using live/dead Bacterial Viability Kit. The results showed that NPs at the concentration of 10 ppm and 20 ppm provided rapid and effective killing of up to 90% and 85% of S. aureus and E. coli within 3 h, respectively. After treatment with 20 ppm and 40 ppm NPs, the bacteria are killed completely. Furthermore, on the basis of assessing the antibacterial effects by SEM, TEM, and AFM, it was found the cell membrane damage of the bacteria caused by direct contact of the bacteria with the NPs was the effective mechanism in the bacterial inactivation. PMID:26046938

  17. Synthesis of stable ultra-small Cu nanoparticles for direct writing flexible electronics

    NASA Astrophysics Data System (ADS)

    Li, Wei; Chen, Minfang

    2014-01-01

    In this study, pure Cu nanoparticles (NPs) have been successfully synthesized and the Cu nano-ink was prepared for direct writing on photo paper using a roller pen. The tri-sodium citrate was used as initial reducing-cum-surfactant agent followed by hydrazine as a second massive reducing agent and cetyltrimethylammonium bromide (CTAB) as extra surfactant agent. From the XRD, TEM, and HR-TEM analyses, the synthesized particles are confirmed to be Cu in spherical shape with sizes range of 2.5 ± 1.0 nm. By analyzing the FT-IR spectroscopy and TGA curves, it was found that the obtained particles capped with tri-sodium citrate and CTAB layers are stable to oxidation up to the temperature 228 °C. The reduced size and enhanced air-stability of the Cu NPs result in an improved particle density upon sintering, which is mainly responsible for the increased conductivity of the Cu patterns. The resistivity of Cu patterns sintered in Ar at 160 °C for 2 h is 7.2 ± 0.6 μΩ cm, which is 4.40 times the bulk Cu resistivity. The drawn Cu lines exhibited excellent integrity and good conductivity, which were experimentally tested. Moreover, a Cu electrode and a sample RFID antenna were successfully made.

  18. Novel Synthesis of Ultra-Small Dextran Coated Maghemite Nanoparticles for MRI and CT Contrast Agents via a Low Temperature Co-Precipitation Reaction.

    PubMed

    Rabias, Ioannis; Fardis, Michael; Kehagias, Thomas; Kletsas, Dimitris; Pratsinis, Harris; Tsitrouli, Danai; Maris, Thomas G; Papavassiliou, George

    2015-01-01

    Ultra-small dextran coated maghemite nanoparticles are synthesized via a low temperature modified co-precipitation method. A monoethylene glycol/water solution of 1:1 molar ratios and a fixed apparatus is used at a constant temperature of 5-10 degrees C. The growth of nanoparticles is prohibited due to low temperature synthesis and differs from usual thermal decomposition methods via Ostwald ripening. Strict temperature control and reaction timing of less than 20 minutes are essential to maintain narrow distribution in particle size. These nanoparticles are water-dispersible and biocompatible by capping with polyethylene glycol ligands. The aqueous suspensions are tested for cytotoxic activity on normal human skin fibroblasts. There is no reduction of the cells' viability at any concentration tested, the highest being 1% v/v of the suspension in culture medium, corresponding to the highest concentrations to be administered in vivo. Initial comparison with a T1 MRI contrast agent in sale shows that maghemite nanoparticles exhibit high r1 and r2 relaxivities in MRI tomography and strong contrast in computed tomography, demonstrating that these nanoparticles can be efficient T1, T2 and CT contrast agents. PMID:26328331

  19. Au Nanocage Functionalized with Ultra-small Fe3O4 Nanoparticles for Targeting T1–T2Dual MRI and CT Imaging of Tumor

    NASA Astrophysics Data System (ADS)

    Wang, Guannan; Gao, Wei; Zhang, Xuanjun; Mei, Xifan

    2016-06-01

    Diagnostic approaches based on multimodal imaging of clinical noninvasive imaging (eg. MRI/CT scanner) are highly developed in recent years for accurate selection of the therapeutic regimens in critical diseases. Therefore, it is highly demanded in the development of appropriate all-in-one multimodal contrast agents (MCAs) for the MRI/CT multimodal imaging. Here a novel ideal MCAs (F-AuNC@Fe3O4) were engineered by assemble Au nanocages (Au NC) and ultra-small iron oxide nanoparticles (Fe3O4) for simultaneous T1–T2dual MRI and CT contrast imaging. In this system, the Au nanocages offer facile thiol modification and strong X-ray attenuation property for CT imaging. The ultra-small Fe3O4 nanoparticles, as excellent contrast agent, is able to provide great enhanced signal of T1- and T2-weighted MRI (r1 = 6.263 mM‑1 s‑1, r2 = 28.117 mM‑1 s‑1) due to their ultra-refined size. After functionalization, the present MCAs nanoparticles exhibited small average size, low aggregation and excellent biocompatible. In vitro and In vivo studies revealed that the MCAs show long-term circulation time, renal clearance properties and outstanding capability of selective accumulation in tumor tissues for simultaneous CT imaging and T1- and T2-weighted MRI. Taken together, these results show that as-prepared MCAs are excellent candidates as MRI/CT multimodal imaging contrast agents.

  20. Au Nanocage Functionalized with Ultra-small Fe3O4 Nanoparticles for Targeting T1–T2Dual MRI and CT Imaging of Tumor

    PubMed Central

    Wang, Guannan; Gao, Wei; Zhang, Xuanjun; Mei, Xifan

    2016-01-01

    Diagnostic approaches based on multimodal imaging of clinical noninvasive imaging (eg. MRI/CT scanner) are highly developed in recent years for accurate selection of the therapeutic regimens in critical diseases. Therefore, it is highly demanded in the development of appropriate all-in-one multimodal contrast agents (MCAs) for the MRI/CT multimodal imaging. Here a novel ideal MCAs (F-AuNC@Fe3O4) were engineered by assemble Au nanocages (Au NC) and ultra-small iron oxide nanoparticles (Fe3O4) for simultaneous T1–T2dual MRI and CT contrast imaging. In this system, the Au nanocages offer facile thiol modification and strong X-ray attenuation property for CT imaging. The ultra-small Fe3O4 nanoparticles, as excellent contrast agent, is able to provide great enhanced signal of T1- and T2-weighted MRI (r1 = 6.263 mM−1 s−1, r2 = 28.117 mM−1 s−1) due to their ultra-refined size. After functionalization, the present MCAs nanoparticles exhibited small average size, low aggregation and excellent biocompatible. In vitro and In vivo studies revealed that the MCAs show long-term circulation time, renal clearance properties and outstanding capability of selective accumulation in tumor tissues for simultaneous CT imaging and T1- and T2-weighted MRI. Taken together, these results show that as-prepared MCAs are excellent candidates as MRI/CT multimodal imaging contrast agents. PMID:27312564

  1. Cobalt ferrite nanoparticles with improved aqueous colloidal stability and electrophoretic mobility

    NASA Astrophysics Data System (ADS)

    Munjal, Sandeep; Khare, Neeraj

    2016-04-01

    We have synthesized CoFe2O4 (CFO) nanoparticles of size ˜ 12.2 nm by hydrothermal synthesis method. To control the size of these CFO nanoparticles, oleic acid was used as a surfactant. The inverse spinel phase of the synthesized nanoparticles was confirmed by X-ray diffraction method. As synthesized oleic acid coated CFO (OA@CFO) nanoparticles has very less electrophoretic mobility in the water and are not water dispersible. These OA@CFO nanoparticles were successfully turned into water soluble phase with a better colloidal aqueous stability, through a chemical treatment using citric acid. The modified citric acid coated CFO (CA@CFO) nanoparticles were dispersible in water and form a stable aqueous solution with high electrophoretic mobility.

  2. Bcl-2-functionalized ultrasmall superparamagnetic iron oxide nanoparticles coated with amphiphilic polymer enhance the labeling efficiency of islets for detection by magnetic resonance imaging

    PubMed Central

    Yang, Bin; Cai, Haolei; Qin, Wenjie; Zhang, Bo; Zhai, Chuanxin; Jiang, Biao; Wu, Yulian

    2013-01-01

    Based on their versatile, biocompatible properties, superparamagnetic iron oxide (SPIO) or ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are utilized for detecting and tracing cells or tumors in vivo. Here, we developed an innoxious and concise synthesis approach for a novel B-cell lymphoma (Bcl)-2 monoclonal antibody-functionalized USPIO nanoparticle coated with an amphiphilic polymer (carboxylated polyethylene glycol monooleyl ether [OE-PEG-COOH]). These nanoparticles can be effectively internalized by beta cells and label primary islet cells, at relatively low iron concentration. The biocompatibility and cytotoxicity of these products were investigated by comparison with the commercial USPIO product, FeraSpin™ S. We also assessed the safe dosage range of the product. Although some cases showed a hypointensity change at the site of transplant, a strong magnetic resonance imaging (MRI) was detectable by a clinical MRI scanner, at field strength of 3.0 Tesla, in vivo, and the iron deposition/attached in islets was confirmed by Prussian blue and immunohistochemistry staining. It is noteworthy that based on our synthesis approach, in future, we could exchange the Bcl-2 with other probes that would be more specific for the targeted cells and that would have better labeling specificity in vivo. The combined results point to the promising potential of the novel Bcl-2-functionalized PEG-USPIO as a molecular imaging agent for in vivo monitoring of islet cells or other cells. PMID:24204136

  3. Facile Scalable Synthesis of TiO2/Carbon Nanohybrids with Ultrasmall TiO2 Nanoparticles Homogeneously Embedded in Carbon Matrix.

    PubMed

    Wang, Xiaoyan; Meng, Jian-Qiang; Wang, Meimei; Xiao, Ying; Liu, Rui; Xia, Yonggao; Yao, Yuan; Metwalli, Ezzeldin; Zhang, Qian; Qiu, Bao; Liu, Zhaoping; Pan, Jing; Sun, Ling-Dong; Yan, Chun-Hua; Müller-Buschbaum, Peter; Cheng, Ya-Jun

    2015-11-01

    A facile scalable synthesis of TiO2/C nanohybrids inspired by polymeric dental restorative materials has been developed, which creates ultrasmall TiO2 nanoparticles homogeneously embedded in the carbon matrix. The average size of the nanoparticles is tuned between about 1 and 5 nm with the carbon content systematically increased from 0% to 65%. Imaging analysis and a scattering technique have been applied to investigate the morphology of the TiO2 nanoparticles. The composition, nature of carbon matrix, crystallinity, and tap density of the TiO2/C nanohybrids have been studied. The application of the TiO2/C nanohybrids as lithium-ion battery anode is demonstrated. Unusual discharge/charge profiles have been exhibited, where characteristic discharge/charge plateaus of crystalline TiO2 are significantly diminished. The tap density, cyclic capacities, and rate performance at high current densities (10 C, 20 C) of the TiO2/C nanohybrid anodes have been effectively improved compared to the bare carbon anode and the TiO2/C nanohybrids with larger particle size. PMID:26465800

  4. Metal-induced self-assembly of peroxiredoxin as a tool for sorting ultrasmall gold nanoparticles into one-dimensional clusters.

    PubMed

    Ardini, Matteo; Giansanti, Francesco; Di Leandro, Luana; Pitari, Giuseppina; Cimini, Annamaria; Ottaviano, Luca; Donarelli, Maurizio; Santucci, Sandro; Angelucci, Francesco; Ippoliti, Rodolfo

    2014-07-21

    Nanomanipulation of matter to create responsive, ordered materials still remains extremely challenging. Supramolecular chemistry has inspired new strategies by which such nanomaterials can be synthesized step by step by exploiting the self-recognition properties of molecules. In this work, the ring-shaped architecture of the 2-Cys peroxiredoxin I protein from Schistosoma mansoni, engineered to have metal ion-binding sites, is used as a template to build up 1D nanoscopic structures through metal-induced self-assembly. Chromatographic and microscopic analyses demonstrate the ability of the protein rings to stack directionally upon interaction with divalent metal ions and form well-defined nanotubes by exploiting the intrinsic recognition properties of the ring surfaces. Taking advantage of such behavior, the rings are then used to capture colloidal Ni(2+)-functionalized ultrasmall gold nanoparticles and arrange them into 1D arrays through stacking into peapod-like complexes. Finally, as the formation of such nano-peapods strictly depends on nanoparticle dimensions, the peroxiredoxin template is used as a colloidal cut-off device to sort by size the encapsulated nanoparticles. These results open up possibilities in developing Prx-based methods to synthesize new advanced functional materials. PMID:24910403

  5. Synthesis of high saturation magnetization FeCo nanoparticles by polyol reduction method

    NASA Astrophysics Data System (ADS)

    Yang, F. J.; Yao, J.; Min, J. J.; Li, J. H.; Chen, X. Q.

    2016-03-01

    FeCo nanoparticles with different compositions were prepared by a polyol reduction method and annealed in gas mixtures. All FeCo nanoparticles show large saturation magnetization (over 220 emu/g). The largest saturation magnetization of 273 emu/g was observed in the Fe55Co45 sample. As for Fe48Co52, the impurity phase of CoFe2O4 existed when nanoparticles were annealed at low temperature (200-400 °C). While annealed at above 450 °C, pure Fe48Co52 nanoparticles with large saturation magnetization of 230 emu/g were obtained. These FeCo nanoparticles with large saturation magnetization have great potential in some industry fields.

  6. Synthesis and controllable oxidation of monodisperse cobalt-doped wüstite nanoparticles and their core-shell stability and exchange-bias stabilization.

    PubMed

    Chen, Chih-Jung; Chiang, Ray-Kuang; Kamali, Saeed; Wang, Sue-Lein

    2015-09-14

    Cobalt-doped wüstite (CWT), Co0.33Fe0.67O, nanoparticles were prepared via the thermal decomposition of CoFe2-oleate complexes in organic solvents. A controllable oxidation process was then performed to obtain Co0.33Fe0.67O/CoFe2O4 core-shell structures with different core-to-shell volume ratios and exchange bias properties. The oxidized core-shell samples with a ∼4 nm CoFe2O4 shell showed good resistance to oxygen transmission. Thus, it is inferred that the cobalt ferrite shell provides a better oxidation barrier performance than magnetite in the un-doped case. The hysteresis loops of the oxidized 19 nm samples exhibited a high exchange bias field (H(E)), an enhanced coercivity field (H(C)), and a pronounced vertical shift, thus indicating the presence of a strong exchange bias coupling effect. More importantly, the onset temperature of H(E) was found to be higher than 200 K, which suggests that cobalt doping increases the Néel temperature (T(N)) of the CWT core. In general, the results show that the homogeneous dispersion of Co in iron precursors improves the stability of the final CWT nanoparticles. Moreover, the CoFe2O4 shells formed following oxidation increase the oxidation resistance of the CWT cores and enhance their anisotropy energy.

  7. Synthesis and controllable oxidation of monodisperse cobalt-doped wüstite nanoparticles and their core-shell stability and exchange-bias stabilization.

    PubMed

    Chen, Chih-Jung; Chiang, Ray-Kuang; Kamali, Saeed; Wang, Sue-Lein

    2015-09-14

    Cobalt-doped wüstite (CWT), Co0.33Fe0.67O, nanoparticles were prepared via the thermal decomposition of CoFe2-oleate complexes in organic solvents. A controllable oxidation process was then performed to obtain Co0.33Fe0.67O/CoFe2O4 core-shell structures with different core-to-shell volume ratios and exchange bias properties. The oxidized core-shell samples with a ∼4 nm CoFe2O4 shell showed good resistance to oxygen transmission. Thus, it is inferred that the cobalt ferrite shell provides a better oxidation barrier performance than magnetite in the un-doped case. The hysteresis loops of the oxidized 19 nm samples exhibited a high exchange bias field (H(E)), an enhanced coercivity field (H(C)), and a pronounced vertical shift, thus indicating the presence of a strong exchange bias coupling effect. More importantly, the onset temperature of H(E) was found to be higher than 200 K, which suggests that cobalt doping increases the Néel temperature (T(N)) of the CWT core. In general, the results show that the homogeneous dispersion of Co in iron precursors improves the stability of the final CWT nanoparticles. Moreover, the CoFe2O4 shells formed following oxidation increase the oxidation resistance of the CWT cores and enhance their anisotropy energy. PMID:26243163

  8. Synthesis of cobalt ferrite nanoparticles from thermolysis of prospective metal-nitrosonaphthol complexes and their photochemical application in removing methylene blue

    NASA Astrophysics Data System (ADS)

    Tavana, Jalal; Edrisi, Mohammad

    2016-03-01

    In this study, cobalt ferrite (CoFe2O4) nanoparticles were synthesized by two novel methods. The first method is based on the thermolysis of metal-NN complexes. In the second method, a template free sonochemical treatment of mixed cobalt and iron chelates of α-nitroso-β-naphthol (NN) was applied. Products prepared through method 1 were spherical, with high specific surface area (54.39 m2 g-1) and small average crystalline size of 13 nm. However, CoFe2O4 nanoparticles prepared by method 2 were in random shapes, a broad range of crystalline sizes and a low specific surface area of 25.46 m2 g-1 though highly pure. A Taguchi experimental design was implemented in method 1 to determine and obtain the optimum catalyst. The structural and morphological properties of products were investigated by x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, Brunauer-Emmett-Teller and dynamic laser light scattering. The crystalline size calculations were performed using Williamson-Hall method on XRD spectrum. The photocatalytic activity of the optimum nanocrystalline cobalt ferrite was investigated for degradation of a representative pollutant, methylene blue (MB), and visible light as energy source. The results showed that some 92% degradation of MB could be achieved for 7 h of visible light irradiation.

  9. Synthesis and dose interval dependent hepatotoxicity evaluation of intravenously administered polyethylene glycol-8000 coated ultra-small superparamagnetic iron oxide nanoparticle on Wistar rats.

    PubMed

    Rajan, Balan; Sathish, Shanmugam; Balakumar, Subramanian; Devaki, Thiruvengadam

    2015-03-01

    Superparamagnetic iron oxide nanoparticles are being used in medical imaging, drug delivery, cancer therapy, and so on. However, there is a direct need to identify any nanotoxicity associated with these nanoparticles. However uncommon, drug-induced liver injury (DILI) is a major health concern that challenges pharmaceutical industry and drug regulatory agencies alike. In this study we have synthesized and evaluated the dose interval dependent hepatotoxicity of polyethylene glycol-8000 coated ultra-small superparamagnetic iron oxide nanoparticles (PUSPIOs). To assess the hepatotoxicity of intravenously injected PUSPIOs, alterations in basic clinical parameters, hematological parameters, hemolysis assay, serum levels of liver marker enzymes, serum and liver lipid peroxidation (LPO) levels, enzymatic antioxidant levels, and finally histology of liver, kidney, spleen, lung, brain, and heart tissues were studied in control and experimental Wistar rat groups over a 30-day period. The results of our study showed a significant increase in the aspartate transaminase (AST) enzyme activity at a dose of 10mg/kg b.w. PUSPIOs twice a week. Besides, alanine transaminase (ALT), alkaline phosphatase (ALP), and gamma-glutamyl transferase (γGT) enzyme activity showed a slender increase when compared with control experimental groups. A significant increase in the serum and liver LPO levels at a dose of 10mg/kg b.w. PUSPIOs twice a week was also observed. Histological analyses of liver, kidney, spleen, lung, brain and heart tissue samples showed no obvious uncharacteristic changes. In conclusion, PUSPIOs were found to posses excellent biocompatibility and Wistar rats showed much better drug tolerance to the dose of 10mg/kg b.w. per week than the dose of 10mg/kg b.w. twice a week for the period of 30 days.

  10. Synthesis and dose interval dependent hepatotoxicity evaluation of intravenously administered polyethylene glycol-8000 coated ultra-small superparamagnetic iron oxide nanoparticle on Wistar rats.

    PubMed

    Rajan, Balan; Sathish, Shanmugam; Balakumar, Subramanian; Devaki, Thiruvengadam

    2015-03-01

    Superparamagnetic iron oxide nanoparticles are being used in medical imaging, drug delivery, cancer therapy, and so on. However, there is a direct need to identify any nanotoxicity associated with these nanoparticles. However uncommon, drug-induced liver injury (DILI) is a major health concern that challenges pharmaceutical industry and drug regulatory agencies alike. In this study we have synthesized and evaluated the dose interval dependent hepatotoxicity of polyethylene glycol-8000 coated ultra-small superparamagnetic iron oxide nanoparticles (PUSPIOs). To assess the hepatotoxicity of intravenously injected PUSPIOs, alterations in basic clinical parameters, hematological parameters, hemolysis assay, serum levels of liver marker enzymes, serum and liver lipid peroxidation (LPO) levels, enzymatic antioxidant levels, and finally histology of liver, kidney, spleen, lung, brain, and heart tissues were studied in control and experimental Wistar rat groups over a 30-day period. The results of our study showed a significant increase in the aspartate transaminase (AST) enzyme activity at a dose of 10mg/kg b.w. PUSPIOs twice a week. Besides, alanine transaminase (ALT), alkaline phosphatase (ALP), and gamma-glutamyl transferase (γGT) enzyme activity showed a slender increase when compared with control experimental groups. A significant increase in the serum and liver LPO levels at a dose of 10mg/kg b.w. PUSPIOs twice a week was also observed. Histological analyses of liver, kidney, spleen, lung, brain and heart tissue samples showed no obvious uncharacteristic changes. In conclusion, PUSPIOs were found to posses excellent biocompatibility and Wistar rats showed much better drug tolerance to the dose of 10mg/kg b.w. per week than the dose of 10mg/kg b.w. twice a week for the period of 30 days. PMID:25721486

  11. Thiolated DNA-based chemistry and control in the structure and optical properties of plasmonic nanoparticles with ultrasmall interior nanogap.

    PubMed

    Oh, Jeong-Wook; Lim, Dong-Kwon; Kim, Gyeong-Hwan; Suh, Yung Doug; Nam, Jwa-Min

    2014-10-01

    The design, synthesis and control of plasmonic nanostructures, especially with ultrasmall plasmonically coupled nanogap (∼1 nm or smaller), are of significant interest and importance in chemistry, nanoscience, materials science, optics and nanobiotechnology. Here, we studied and established the thiolated DNA-based synthetic principles and methods in forming and controlling Au core-nanogap-Au shell structures [Au-nanobridged nanogap particles (Au-NNPs)] with various interior nanogap and Au shell structures. We found that differences in the binding affinities and modes among four different bases to Au core, DNA sequence, DNA grafting density and chemical reagents alter Au shell growth mechanism and interior nanogap-forming process on thiolated DNA-modified Au core. Importantly, poly A or poly C sequence creates a wider interior nanogap with a smoother Au shell, while poly T sequence results in a narrower interstitial interior gap with rougher Au shell, and on the basis of the electromagnetic field calculation and experimental results, we unraveled the relationships between the width of the interior plasmonic nanogap, Au shell structure, electromagnetic field and surface-enhanced Raman scattering. These principles and findings shown in this paper offer the fundamental basis for the thiolated DNA-based chemistry in forming and controlling metal nanostructures with ∼1 nm plasmonic gap and insight in the optical properties of the plasmonic NNPs, and these plasmonic nanogap structures are useful as strong and controllable optical signal-generating nanoprobes.

  12. Antibiotic-free nanotherapeutics: ultra-small, mucus-penetrating solid lipid nanoparticles enhance the pulmonary delivery and anti-virulence efficacy of novel quorum sensing inhibitors.

    PubMed

    Nafee, Noha; Husari, Ayman; Maurer, Christine K; Lu, Cenbin; de Rossi, Chiara; Steinbach, Anke; Hartmann, Rolf W; Lehr, Claus-Michael; Schneider, Marc

    2014-10-28

    Cystic fibrosis (CF) is a genetic disease mainly manifested in the respiratory tract. Pseudomonas aeruginosa (P. aeruginosa) is the most common pathogen identified in cultures of the CF airways, however, its eradication with antibiotics remains challenging as it grows in biofilms that counterwork human immune response and dramatically decrease susceptibility to antibiotics. P. aeruginosa regulates pathogenicity via a cell-to-cell communication system known as quorum sensing (QS) involving the virulence factor (pyocyanin), thus representing an attractive target for coping with bacterial pathogenicity. The first in vivo potent QS inhibitor (QSI) was recently developed. Nevertheless, its lipophilic nature might hamper its penetration of non-cellular barriers such as mucus and bacterial biofilms, which limits its biomedical application. Successful anti-infective inhalation therapy necessitates proper design of a biodegradable nanocarrier allowing: 1) high loading and prolonged release, 2) mucus penetration, 3) effective pulmonary delivery, and 4) maintenance of the anti-virulence activity of the QSI. In this context, various pharmaceutical lipids were used to prepare ultra-small solid lipid nanoparticles (us-SLNs) by hot melt homogenization. Plain and QSI-loaded SLNs were characterized in terms of colloidal properties, drug loading, in vitro release and acute toxicity on Calu-3 cells. Mucus penetration was studied using a newly-developed confocal microscopy technique based on 3D-time-lapse imaging. For pulmonary application, nebulization efficiency of SLNs and lung deposition using next generation impactor (NGI) were performed. The anti-virulence efficacy was investigated by pyocyanin formation in P. aeruginosa cultures. Ultra-small SLNs (<100nm diameter) provided high encapsulation efficiency (68-95%) according to SLN composition, high burst in phosphate buffer saline compared to prolonged release of the payload over >8h in simulated lung fluid with minor burst. All

  13. Polymer-Lipid Hybrid Theranostic Nanoparticles Co-Delivering Ultrasmall Superparamagnetic Iron Oxide and Paclitaxel for Targeted Magnetic Resonance Imaging and Therapy in Atherosclerotic Plaque.

    PubMed

    Dong, Yinmei; Chen, Huaiwen; Chen, Chao; Zhang, Xuefeng; Tian, Xia; Zhang, Yingying; Shi, Zhang; Liu, Qi

    2016-06-01

    Magnetic resonance imaging (MRI) combined with ultrasmall superparamagnetic iron oxide (USPIO) is effective for the detection of atherosclerotic (AS) plaque, and paclitaxel is effective for the treatment of AS. C11 is a polypeptide with high affinity and specificity for collagen IV. It is abundantly expressed in the outer layer of AS plaque. This study aimed to develop USPIO + paclitaxel-loaded polymer-lipid hybrid theranostic nanoparticles conjugated with C11 (UP-NP-C11) for simultaneous imaging and treatment AS plaque. UP-NP-C11 was developed by the nanoprecipitation method, and the theranostics of AS plaque by UP-NP-C11 were evaluated both in vitro and in the rabbit AS model. UP-NP-C11 was of desired particle size (140.2 nm), showed encapsulation efficiency of 35.5% and 55.2% for USPIO and paclitaxel, respectively, and had drug release profile. The accumulation of USPIO in Matrigel (containing abundant collagen IV) and macrophages coated on the Matrigel was significantly higher in the UP-NP-C11-treated group than in the group treated by UP-NP (USPIO + paclitaxel-loaded nanoparticles). Thus, UP-NP-C11 exerted better growth inhibitory effect and MRI ability in macrophages than UP-NP. Significantly, UP-NP-C11 showed better in vivo MRI ability and therapeutic effect in rabbit AS plaque than UP-NP and commercial USPIO + paclitaxel, and Prussian blue staining revealed significantly greater accumulation of USPIOs in the UP-NP-C11-treated group than in the control group. Furthermore, UP-NP-C11 did not cause severe toxicity to the rabbits. UP-NP-C11 represents a potential approach for targeted MRI and therapy in AS plaque. PMID:27319218

  14. Grain Size Control of the Magnetic Nanoparticles by Solid State Route Modification

    NASA Astrophysics Data System (ADS)

    Barreto, A. C. H.; Santiago, V. R.; Freire, R. M.; Mazzetto, S. E.; Sasaki, J. M.; Vasconcelos, I. F.; Denardin, J. C.; Mele, Giuseppe; Carbone, Luigi; Fechine, P. B. A.

    2013-07-01

    The CoFe2O4 and NiFe2O4 nanoparticles were synthesized exploiting a co-precipitation method and afterward calcinated at 400 °C through two different experimental apparatus: a conventional muffle and rotatory oven. X-ray diffraction (XRD) analysis revealed that nanocrystalline ferrites grew with a face center cubic structure (fcc) and Fd3 m symmetry space group. XRD, transmission electron microscopy, and magnetic measurements confirmed the compositional homogeneity and the narrow size particle distribution (6-8 nm) of the sample thermally treated in a rotary oven, in all likelihood due to the sample's constant turning movement. The size of the magnetic particles is extremely important and influences the choice of a potential technological application. For this reason, our study emerges as a new and simple innovating procedure to control the size of magnetic nanoparticles.

  15. Polyethylene glycol-covered ultra-small Gd2O3 nanoparticles for positive contrast at 1.5 T magnetic resonance clinical scanning

    NASA Astrophysics Data System (ADS)

    Fortin, Marc-André; Petoral, Rodrigo M., Jr.; Söderlind, Fredrik; Klasson, A.; Engström, Maria; Veres, Teodor; Käll, Per-Olof; Uvdal, Kajsa

    2007-10-01

    The size distribution and magnetic properties of ultra-small gadolinium oxide crystals (US-Gd2O3) were studied, and the impact of polyethylene glycol capping on the relaxivity constants (r1, r2) and signal intensity with this contrast agent was investigated. Size distribution and magnetic properties of US-Gd2O3 nanocrystals were measured with a TEM and PPMS magnetometer. For relaxation studies, diethylene glycol (DEG)-capped US-Gd2O3 nanocrystals were reacted with PEG-silane (MW 5000). Suspensions were adequately dialyzed in water to eliminate traces of Gd3+ and surfactants. The particle hydrodynamic radius was measured with dynamic light scattering (DLS) and the proton relaxation times were measured with a 1.5 T MRI scanner. Parallel studies were performed with DEG-Gd2O3 and PEG-silane-SPGO (Gd2O3,< 40 nm diameter). The small and narrow size distribution of US-Gd2O3 was confirmed with TEM (~3 nm) and DLS. PEG-silane-US-Gd2O3 relaxation parameters were twice as high as for Gd-DTPA and the r2/r1 ratio was 1.4. PEG-silane-SPGO gave low r1 relaxivities and high r2/r1 ratios, less compatible with positive contrast agent requirements. Higher r1 were obtained with PEG-silane in comparison to DEG-Gd2O3. Treatment of DEG-US-Gd2O3 with PEG-silane provides enhanced relaxivity while preventing aggregation of the oxide cores. This study confirms that PEG-covered Gd2O3 nanoparticles can be used for positively contrasted MR applications requiring stability, biocompatible coatings and nanocrystal functionalization.

  16. Surface-Enhanced Raman Scattering Active Plasmonic Nanoparticles with Ultrasmall Interior Nanogap for Multiplex Quantitative Detection and Cancer Cell Imaging.

    PubMed

    Li, Jiuxing; Zhu, Zhi; Zhu, Bingqing; Ma, Yanli; Lin, Bingqian; Liu, Rudi; Song, Yanling; Lin, Hui; Tu, Song; Yang, Chaoyong

    2016-08-01

    Due to its large enhancement effect, nanostructure-based surface-enhanced Raman scattering (SERS) technology had been widely applied for bioanalysis and cell imaging. However, most SERS nanostructures suffer from poor signal reproducibility, which hinders the application of SERS nanostructures in quantitative detection. We report an etching-assisted approach to synthesize SERS-active plasmonic nanoparticles with 1 nm interior nanogap for multiplex quantitative detection and cancer cell imaging. Raman dyes and methoxy poly(ethylene glycol) thiol (mPEG-SH) were attached to gold nanoparticles (AuNPs) to prepare gold cores. Next, Ag atoms were deposited on gold cores in the presence of Pluronic F127 to form a Ag shell. HAuCl4 was used to etch the Ag shell and form an interior nanogap in Au@AgAuNPs, leading to increased Raman intensity of dyes. SERS intensity distribution of Au@AgAuNPs was found to be more uniform than that of aggregated AuNPs. Finally, Au@AgAuNPs were used for multiplex quantitative detection and cancer cell imaging. With the advantages of simple and rapid preparation of Au@AgAuNPs with highly uniform, stable, and reproducible Raman intensity, the method reported here will widen the applications of SERS-active nanoparticles in diagnostics and imaging. PMID:27385563

  17. Mechanisms of cell penetration and cytotoxicity of ultrasmall Au nanoparticles conjugated to doxorubicin and/or targeting peptides

    NASA Astrophysics Data System (ADS)

    Nadeau, Jay; Poon, Wilson; Zhang, Xuan

    2015-03-01

    The goals of this work were to determine whether conjugation of any of four selected peptides to Au nanoparticles improved their delivery to B16 melanoma in vitro and in vivo. In in vitro cytotoxicity assays, peptides and conjugates were endocytosed but did not escape from endosomes. None of the peptides showed any cytotoxicity, with or without conjugation to the nanoparticles. The combination of peptides and doxorubicin did not improve upon the cytotoxicity of gold-doxorubicin alone. We then tested targeting in vivo using inductively coupled plasma mass spectrometry to quantify the concentration of Au in the organs of B16 tumor-bearing mice 4, 24, and 72 h after intravenous Au nanoparticle injection. These experiments showed that in some cases, peptide conjugation improved upon the enhanced permeability and retention (EPR) effect. A peptide based upon the myxoma virus and the cyclic RGD peptide were both effective at tumor targeting; myxoma was more effective with un-PEGylated particles, and cRGD with PEGylated particles. The FREG and melanocyte stimulating hormone (MSH) peptides did not improve targeting. These results suggest that these peptides may improve delivery of Au particles to tumors, but also may prevent entry of particles into cell nuclei.

  18. Acid-functionalized nanoparticles for biomass hydrolysis

    NASA Astrophysics Data System (ADS)

    Pena Duque, Leidy Eugenia

    Cellulosic ethanol is a renewable source of energy. Lignocellulosic biomass is a complex material composed mainly of cellulose, hemicellulose, and lignin. Biomass pretreatment is a required step to make sugar polymers liable to hydrolysis. Mineral acids are commonly used for biomass pretreatment. Using acid catalysts that can be recovered and reused could make the process economically more attractive. The overall goal of this dissertation is the development of a recyclable nanocatalyst for the hydrolysis of biomass sugars. Cobalt iron oxide nanoparticles (CoFe2O4) were synthesized to provide a magnetic core that could be separated from reaction using a magnetic field and modified to carry acid functional groups. X-ray diffraction (XRD) confirmed the crystal structure was that of cobalt spinel ferrite. CoFe2O4 were covered with silica which served as linker for the acid functions. Silica-coated nanoparticles were functionalized with three different acid functions: perfluoropropyl-sulfonic acid, carboxylic acid, and propyl-sulfonic acid. Transmission electron microscope (TEM) images were analyzed to obtain particle size distributions of the nanoparticles. Total carbon, nitrogen, and sulfur were quantified using an elemental analyzer. Fourier transform infra-red spectra confirmed the presence of sulfonic and carboxylic acid functions and ion-exchange titrations accounted for the total amount of catalytic acid sites per nanoparticle mass. These nanoparticles were evaluated for their performance to hydrolyze the beta-1,4 glycosidic bond of the cellobiose molecule. Propyl-sulfonic (PS) and perfluoropropyl-sulfonic (PFS) acid functionalized nanoparticles catalyzed the hydrolysis of cellobiose significantly better than the control. PS and PFS were also evaluated for their capacity to solubilize wheat straw hemicelluloses and performed better than the control. Although PFS nanoparticles were stronger acid catalysts, the acid functions leached out of the nanoparticle during

  19. Strain Field in Ultrasmall Gold Nanoparticles Supported on Cerium-Based Mixed Oxides. Key Influence of the Support Redox State.

    PubMed

    López-Haro, Miguel; Yoshida, Kenta; Del Río, Eloy; Pérez-Omil, José A; Boyes, Edward D; Trasobares, Susana; Zuo, Jian-Min; Gai, Pratibha L; Calvino, José J

    2016-05-01

    Using a method that combines experimental and simulated Aberration-Corrected High Resolution Electron Microscopy images with digital image processing and structure modeling, strain distribution maps within gold nanoparticles relevant to real powder type catalysts, i.e., smaller than 3 nm, and supported on a ceria-based mixed oxide have been determined. The influence of the reduction state of the support and particle size has been examined. In this respect, it has been proven that reduction even at low temperatures induces a much larger compressive strain on the first {111} planes at the interface. This increase in compression fully explains, in accordance with previous DFT calculations, the loss of CO adsorption capacity of the interface area previously reported for Au supported on ceria-based oxides.

  20. Magnetic nanoparticles for "smart liposomes".

    PubMed

    Nakayama, Yoshitaka; Mustapić, Mislav; Ebrahimian, Haleh; Wagner, Pawel; Kim, Jung Ho; Hossain, Md Shahriar Al; Horvat, Joseph; Martinac, Boris

    2015-12-01

    Liposomal drug delivery systems (LDDSs) are promising tools used for the treatment of diseases where highly toxic pharmacological agents are administered. Currently, destabilising LDDSs by a specific stimulus at a target site remains a major challenge. The bacterial mechanosensitive channel of large conductance (MscL) presents an excellent candidate biomolecule that could be employed as a remotely controlled pore-forming nanovalve for triggered drug release from LDDSs. In this study, we developed superparamagnetic nanoparticles for activation of the MscL nanovalves by magnetic field. Synthesised CoFe2O4 nanoparticles with the radius less than 10 nm were labelled by SH groups for attachment to MscL. Activation of MscL by magnetic field with the nanoparticles attached was examined by the patch clamp technique showing that the number of activated channels under ramp pressure increased upon application of the magnetic field. In addition, we have not observed any cytotoxicity of the nanoparticles in human cultured cells. Our study suggests the possibility of using magnetic nanoparticles as a specific trigger for activation of MscL nanovalves for drug release in LDDSs. PMID:26184724

  1. Ultra-small Nd3+-doped nanoparticles as near-infrared luminescent biolabels of hemin in bacteria

    NASA Astrophysics Data System (ADS)

    Xi, Yonglan; Chang, Zhizhou; Ye, Xiaomei; Huang, Hongying; Huang, Yanan; Xiao, Qingbo; Lin, Hongzhen

    2016-01-01

    Near-infrared (NIR) luminescent Nd3+-doped nanoparticles (NPs) have attracted considerable attention in bioimaging and biodetection. Here, we demonstrate sub-6 nm NaGdF4:Nd3+,Fe3+ NPs as luminescent biolabels of hemin molecules that act as the exogenous electron carriers in microbial communities. Contrary to the severe quenching of the visible luminescence for either upconverting or downconverting NPs, the Nd3+-doped NPs show superior properties in avoiding the optical absorption of hemin within the UV and visible spectral regions. A detailed examination showed that the Nd3+-doped NPs exhibit no obvious toxic effects on the microbial communities and show scarce influence on the characteristics of labeled hemin molecules in enhancing the reducing power of the fermentation system. More importantly, by monitoring the NIR luminescence of Nd3+-doped NPs, the selective accumulation of exogenous electron carriers in bacteria that are lacking reducing power has been revealed for the first time. The application of Nd3+-doped NPs as biolabels in bacteria would provide new opportunities for further unravelling the role of exogenous electron carriers in anaerobic digestion.Near-infrared (NIR) luminescent Nd3+-doped nanoparticles (NPs) have attracted considerable attention in bioimaging and biodetection. Here, we demonstrate sub-6 nm NaGdF4:Nd3+,Fe3+ NPs as luminescent biolabels of hemin molecules that act as the exogenous electron carriers in microbial communities. Contrary to the severe quenching of the visible luminescence for either upconverting or downconverting NPs, the Nd3+-doped NPs show superior properties in avoiding the optical absorption of hemin within the UV and visible spectral regions. A detailed examination showed that the Nd3+-doped NPs exhibit no obvious toxic effects on the microbial communities and show scarce influence on the characteristics of labeled hemin molecules in enhancing the reducing power of the fermentation system. More importantly, by

  2. Ultrasmall PdmMn1-mOx binary alloyed nanoparticles on graphene catalysts for ethanol oxidation in alkaline media

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohammad Shamsuddin; Park, Dongchul; Jeon, Seungwon

    2016-03-01

    A rare combination of graphene (G)-supported palladium and manganese in mixed-oxides binary alloyed catalysts (BACs) have been synthesized with the addition of Pd and Mn metals in various ratios (G/PdmMn1-mOx) through a facile wet-chemical method and employed as an efficient anode catalyst for ethanol oxidation reaction (EOR) in alkaline fuel cells. The as prepared G/PdmMn1-mOx BACs have been characterized by several instrumental techniques; the transmission electron microscopy images show that the ultrafine alloyed nanoparticles (NPs) are excellently monodispersed onto the G. The Pd and Mn in G/PdmMn1-mOx BACs have been alloyed homogeneously, and Mn presents in mixed-oxidized form that resulted by X-ray diffraction. The electrochemical performances, kinetics and stability of these catalysts toward EOR have been evaluated using cyclic voltammetry in 1 M KOH electrolyte. Among all G/PdmMn1-mOx BACs, the G/Pd0.5Mn0.5Ox catalyst has shown much superior mass activity and incredible stability than that of pure Pd catalysts (G/Pd1Mn0Ox, Pd/C and Pt/C). The well dispersion, ultrafine size of NPs and higher degree of alloying are the key factor for enhanced and stable EOR electrocatalysis on G/Pd0.5Mn0.5Ox.

  3. Magnetic properties of CoFe2O4 thin films prepared by a sol-gel method

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Gwang; Park, Jae Yun; Oh, Young-Jei; Kim, Chul Sung

    1998-09-01

    Thin films with cobalt ferrite layers on thermally oxidized silicon wafers were fabricated by a sol-gel method. Magnetic and structural properties of the films were investigated with an x-ray diffractometer, a vibrating sample magnetometer and atomic force microscopy. The crystallization temperature for Co ferrite thin films was determined by using Mössbauer spectroscopy. Co ferrite films annealed at and above 450 °C have only a single phase spinel structure without any preferred crystallite orientation. Their rms surface roughness is less than 3 nm and the size of grains is about 30 nm for annealing temperatures greater than 650 °C. Films fired at and above 550 °C have moderate saturation magnetization and there is no significant difference of their magnetic properties for external fields applied parallel and perpendicular to their planes. The coercivity shows a strong dependence on the annealing temperature.

  4. Magnetic structure of Fe-doped CoFe2O4 probed by x-ray magnetic spectroscopies

    NASA Astrophysics Data System (ADS)

    Moyer, J. A.; Vaz, C. A. F.; Arena, D. A.; Kumah, D.; Negusse, E.; Henrich, V. E.

    2011-08-01

    The magnetic properties of iron-doped cobalt ferrite (Co1-xFe2+xO4) (001) thin films grown epitaxially on MgO (001) substrates are investigated by superconducting quantum interference device magnetometry and soft x-ray magnetic linear and circular dichroisms. All Co1-xFe2+xO4 (0.01 ⩽ x ⩽ 0.63) samples have out-of-plane magnetic easy axes and large coercive fields, unlike Fe3O4, due to a large Co2+ orbital moment. The magnetic moments for those samples are significantly reduced from their bulk values; however, as x increases, the magnetic moments tend nearer to their bulk values and increase more rapidly as x approaches 1. This reduction in magnetic moment is attributed to spin canting among the Co2+ cations, owing to a small in-plane tensile strain in the film and to an increased antiferromagnetic alignment among all the cations caused by a partially inverse spinel cubic structure and the likely presence of antiphase boundaries. Our results show that small changes in stoichiometry can lead to significant changes in the magnetic moment of Co1-xFe2+xO4, especially at large values of x.

  5. Structural, electrical, and optomagnetic tweaking of Zn doped CoFe2-xZnxO4-δ nanoparticles

    NASA Astrophysics Data System (ADS)

    Agrawal, Shraddha; Parveen, Azra; Azam, Ameer

    2016-09-01

    Nanoparticles of pure and Zn doped CoFe2O4 of the composition CoFe2-xZnxO4-δ (x=0, 0.05, 0.10, 0.15) have been successfully synthesized by microwave gel combustion. The microstructural and compositional analyses were carried out by X-ray diffraction, Scanning Electron Microscopy. The crystallite size was found to increase with the increase in the Zn content. The dielectric constant (ε) and A.C. conductivity were studied as a function of frequency and temperature and were explained on the basis of Maxwell-Wagner model and electron hopping respectively. The energy band gap was found to decrease gradually with Zn doping. The magnetic measurements, depicts an increase in magnetization with the increase in Zn concentration, which in turn shows a strong dependency on the particle size. The magnetic hysteresis loop confirms the ferromagnetic nature.

  6. Synthesis and controllable oxidation of monodisperse cobalt-doped wüstite nanoparticles and their core-shell stability and exchange-bias stabilization

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Jung; Chiang, Ray-Kuang; Kamali, Saeed; Wang, Sue-Lein

    2015-08-01

    Cobalt-doped wüstite (CWT), Co0.33Fe0.67O, nanoparticles were prepared via the thermal decomposition of CoFe2-oleate complexes in organic solvents. A controllable oxidation process was then performed to obtain Co0.33Fe0.67O/CoFe2O4 core-shell structures with different core-to-shell volume ratios and exchange bias properties. The oxidized core-shell samples with a ~4 nm CoFe2O4 shell showed good resistance to oxygen transmission. Thus, it is inferred that the cobalt ferrite shell provides a better oxidation barrier performance than magnetite in the un-doped case. The hysteresis loops of the oxidized 19 nm samples exhibited a high exchange bias field (HE), an enhanced coercivity field (HC), and a pronounced vertical shift, thus indicating the presence of a strong exchange bias coupling effect. More importantly, the onset temperature of HE was found to be higher than 200 K, which suggests that cobalt doping increases the Néel temperature (TN) of the CWT core. In general, the results show that the homogeneous dispersion of Co in iron precursors improves the stability of the final CWT nanoparticles. Moreover, the CoFe2O4 shells formed following oxidation increase the oxidation resistance of the CWT cores and enhance their anisotropy energy.Cobalt-doped wüstite (CWT), Co0.33Fe0.67O, nanoparticles were prepared via the thermal decomposition of CoFe2-oleate complexes in organic solvents. A controllable oxidation process was then performed to obtain Co0.33Fe0.67O/CoFe2O4 core-shell structures with different core-to-shell volume ratios and exchange bias properties. The oxidized core-shell samples with a ~4 nm CoFe2O4 shell showed good resistance to oxygen transmission. Thus, it is inferred that the cobalt ferrite shell provides a better oxidation barrier performance than magnetite in the un-doped case. The hysteresis loops of the oxidized 19 nm samples exhibited a high exchange bias field (HE), an enhanced coercivity field (HC), and a pronounced vertical shift, thus

  7. Giant enhancement of upconversion in ultra-small Er³⁺/Yb³⁺:NaYF₄ nanoparticles via laser annealing.

    PubMed

    Bednarkiewicz, A; Wawrzynczyk, D; Gagor, A; Kepinski, L; Kurnatowska, M; Krajczyk, L; Nyk, M; Samoc, M; Strek, W

    2012-04-13

    Most of the synthesis routes of lanthanide-doped phosphors involve thermal processing which results in nanocrystallite growth, stabilization of the crystal structure and augmentation of luminescence intensity. It is of great interest to be able to transform the sample in a spatially localized manner, which may lead to many applications like 2D and 3D data storage, anti-counterfeiting protection, novel design bio-sensors and, potentially, to fabrication of metamaterials, 3D photonic crystals or plasmonic devices. Here we demonstrate irreversible spatially confined infrared-laser-induced annealing (LIA) achieved in a thin layer of dried colloidal solution of ultra-small ∼8 nm NaYF₄ nanocrystals (NCs) co-doped with 2% Er³⁺ and 20% Yb³⁺ ions under a localized tightly focused beam from a continuous wave 976 nm medium power laser diode excitation. The LIA results from self-heating due to non-radiative relaxation accompanying the NIR laser energy upconversion in lanthanide ions. We notice that localized LIA appears at optical power densities as low as 15.5 kW cm⁻² (∼354 ± 29 mW) threshold in spots of 54 ± 3 µm diameter obtained with a 10 × microscope objective. In the course of detailed studies, a complete recrystallization to different phases and giant 2-3 order enhancement in luminescence yield is found. Our results are highly encouraging and let us conclude that the upconverting ultra-small lanthanide-doped nanophosphors are particularly promising for direct laser writing applications.

  8. Influence of nanoparticle-membrane electrostatic interactions on membrane fluidity and bending elasticity.

    PubMed

    Santhosh, Poornima Budime; Velikonja, Aljaž; Perutkova, Šarka; Gongadze, Ekaterina; Kulkarni, Mukta; Genova, Julia; Eleršič, Kristina; Iglič, Aleš; Kralj-Iglič, Veronika; Ulrih, Nataša Poklar

    2014-02-01

    The aim of this work is to investigate the effect of electrostatic interactions between the nanoparticles and the membrane lipids on altering the physical properties of the liposomal membrane such as fluidity and bending elasticity. For this purpose, we have used nanoparticles and lipids with different surface charges. Positively charged iron oxide (γ-Fe2O3) nanoparticles, neutral and negatively charged cobalt ferrite (CoFe2O4) nanoparticles were encapsulated in neutral lipid 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine and negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine lipid mixture. Membrane fluidity was assessed through the anisotropy measurements using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene. Though the interaction of both the types of nanoparticles reduced the membrane fluidity, the results were more pronounced in the negatively charged liposomes encapsulated with positively charged iron oxide nanoparticles due to strong electrostatic attractions. X-ray photoelectron spectroscopy results also confirmed the presence of significant quantity of positively charged iron oxide nanoparticles in negatively charged liposomes. Through thermally induced shape fluctuation measurements of the giant liposomes, a considerable reduction in the bending elasticity modulus was observed for cobalt ferrite nanoparticles. The experimental results were supported by the simulation studies using modified Langevin-Poisson-Boltzmann model. PMID:24309194

  9. Dendrimer-Templated Ultrasmall and Multifunctional Photothermal Agents for Efficient Tumor Ablation.

    PubMed

    Zhou, Zhengjie; Wang, Yitong; Yan, Yang; Zhang, Qiang; Cheng, Yiyun

    2016-04-26

    Ultrasmall and multifunctional nanoparticles are highly desirable for photothermal cancer therapy, but the synthesis of these nanoparticles remains a huge challenge. Here, we used a dendrimer as a template to synthesize ultrasmall photothermal agents and further modified them with multifunctional groups. Dendrimer-encapsulated nanoparticles (DENPs) including copper sulfide, platinum, and palladium nanoparticles possessed a sub-5 nm size and exhibited an excellent photothermal effect. DENPs were further modified with TAT or RGD peptides to facilitate their cellular uptake and targeting delivery to tumors. They were also decorated with fluorescent probes for real-time imaging and tracking of the particles' distribution. The in vivo study revealed RGD-modified DENPs efficiently reduced the tumor growth upon near-infrared irradiation. In all, our study provides a facile and flexible scaffold to prepare ultrasmall and multifunctional photothermal agents. PMID:27054555

  10. Enigmatic, ultrasmall, uncultivated Archaea

    SciTech Connect

    Baker, Brett J.; Comolli, Luis; Dick, Gregory J.; Hauser, Loren John; Hyatt, Philip Douglas; Dill, Brian; Land, Miriam L; Verberkmoes, Nathan C; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2010-01-01

    Metagenomics has provided access to genomes of as yet uncultivated microorganisms in natural environments, yet there are gaps in our knowledge particularly for Archaea that occur at relatively low abundance and in extreme environments. Ultrasmall cells (<500 nm in diameter) from lineages without cultivated representatives that branch near the crenarchaeal/euryarchaeal divide have been detected in a variety of acidic ecosystems. We reconstructed composite, near-complete 1-Mb genomes for three lineages, referred to as ARMAN (archaeal Richmond Mine acidophilic nanoorganisms), from environmental samples and a biofilm filtrate. Genes of two lineages are among the smallest yet described, enabling a 10% higher coding density than found genomes of the same size, and there are noncontiguous genes. No biological function could be inferred for up to 45% of genes and no more than 63% of the predicted proteins could be assigned to a revised set of archaeal clusters of orthologous groups. Some core metabolic genes are more common in Crenarchaeota than Euryarchaeota, up to 21% of genes have the highest sequence identity to bacterial genes, and 12 belong to clusters of orthologous groups that were previously exclusive to bacteria. A small subset of 3D cryo-electron tomographic reconstructions clearly show penetration of the ARMAN cell wall and cytoplasmic membranes by protuberances extended from cells of the archaeal order Thermoplasmatales. Interspecies interactions, the presence of a unique internal tubular organelle [Comolli, et al. (2009) ISME J 3:159 167], and many genes previously only affiliated with Crenarchaea or Bacteria indicate extensive unique physiology in organisms that branched close to the time that Cren- and Euryarchaeotal lineages diverged.

  11. Enigmatic, ultrasmall, uncultivated Archaea

    SciTech Connect

    Baker, Brett J.; Comolli, Luis; Dick, Gregory J.; Hauser, Loren John; Hyatt, Philip Douglas; Dill, Brian; Land, Miriam L; Verberkmoes, Nathan C; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2010-01-01

    Metagenomics has provided access to genomes of as yet uncultivated microorganisms in natural environments, yet there are gaps in our knowledge-particularly for Archaea-that occur at relatively low abundance and in extreme environments. Ultrasmall cells (<500 nm in diameter) from lineages without cultivated representatives that branch near the crenarchaeal/euryarchaeal divide have been detected in a variety of acidic ecosystems. We reconstructed composite, near-complete similar to 1-Mb genomes for three lineages, referred to as ARMAN (archaeal Richmond Mine acidophilic nanoorganisms), from environmental samples and a biofilm filtrate. Genes of two lineages are among the smallest yet described, enabling a 10% higher coding density than found genomes of the same size, and there are noncontiguous genes. No biological function could be inferred for up to 45% of genes and no more than 63% of the predicted proteins could be assigned to a revised set of archaeal clusters of orthologous groups. Some core metabolic genes are more common in Crenarchaeota than Euryarchaeota, up to 21% of genes have the highest sequence identity to bacterial genes, and 12 belong to clusters of orthologous groups that were previously exclusive to bacteria. A small subset of 3D cryo-electron tomographic reconstructions clearly show penetration of the ARMAN cell wall and cytoplasmic membranes by protuberances extended from cells of the archaeal order Thermoplasmatales. Interspecies interactions, the presence of a unique internal tubular organelle [Comolli, et al. (2009) ISME J 3: 159-167], and many genes previously only affiliated with Crenarchaea or Bacteria indicate extensive unique physiology in organisms that branched close to the time that Cren- and Euryarchaeotal lineages diverged.

  12. Enigmatic, ultrasmall, uncultivated Archaea

    PubMed Central

    Baker, Brett J.; Comolli, Luis R.; Dick, Gregory J.; Hauser, Loren J.; Hyatt, Doug; Dill, Brian D.; Land, Miriam L.; VerBerkmoes, Nathan C.; Hettich, Robert L.; Banfield, Jillian F.

    2010-01-01

    Metagenomics has provided access to genomes of as yet uncultivated microorganisms in natural environments, yet there are gaps in our knowledge—particularly for Archaea—that occur at relatively low abundance and in extreme environments. Ultrasmall cells (<500 nm in diameter) from lineages without cultivated representatives that branch near the crenarchaeal/euryarchaeal divide have been detected in a variety of acidic ecosystems. We reconstructed composite, near-complete ~1-Mb genomes for three lineages, referred to as ARMAN (archaeal Richmond Mine acidophilic nanoorganisms), from environmental samples and a biofilm filtrate. Genes of two lineages are among the smallest yet described, enabling a 10% higher coding density than found genomes of the same size, and there are noncontiguous genes. No biological function could be inferred for up to 45% of genes and no more than 63% of the predicted proteins could be assigned to a revised set of archaeal clusters of orthologous groups. Some core metabolic genes are more common in Crenarchaeota than Euryarchaeota, up to 21% of genes have the highest sequence identity to bacterial genes, and 12 belong to clusters of orthologous groups that were previously exclusive to bacteria. A small subset of 3D cryo-electron tomographic reconstructions clearly show penetration of the ARMAN cell wall and cytoplasmic membranes by protuberances extended from cells of the archaeal order Thermoplasmatales. Interspecies interactions, the presence of a unique internal tubular organelle [Comolli, et al. (2009) ISME J 3:159–167], and many genes previously only affiliated with Crenarchaea or Bacteria indicate extensive unique physiology in organisms that branched close to the time that Cren- and Euryarchaeotal lineages diverged. PMID:20421484

  13. Structural and magnetic properties of cobalt-doped iron oxide nanoparticles prepared by solution combustion method for biomedical applications

    PubMed Central

    Venkatesan, Kaliyamoorthy; Rajan Babu, Dhanakotti; Kavya Bai, Mane Prabhu; Supriya, Ravi; Vidya, Radhakrishnan; Madeswaran, Saminathan; Anandan, Pandurangan; Arivanandhan, Mukannan; Hayakawa, Yasuhiro

    2015-01-01

    Cobalt-doped iron oxide nanoparticles were prepared by solution combustion technique. The structural and magnetic properties of the prepared samples were also investigated. The average crystallite size of cobalt ferrite (CoFe2O4) magnetic nanoparticle was calculated using Scherrer equation, and it was found to be 16±5 nm. The particle size was measured by transmission electron microscope. This value was found to match with the crystallite size calculated by Scherrer equation corresponding to the prominent intensity peak (311) of X-ray diffraction. The high-resolution transmission electron microscope image shows clear lattice fringes and high crystallinity of cobalt ferrite magnetic nanoparticles. The synthesized magnetic nanoparticles exhibited the saturation magnetization value of 47 emu/g and coercivity of 947 Oe. The anti-microbial activity of cobalt ferrite nanoparticles showed better results as an anti-bacterial agent. The affinity constant was determined for the nanoparticles, and the cytotoxicity studies were conducted for the cobalt ferrite nanoparticles at different concentrations and the results are discussed. PMID:26491320

  14. Structural and magnetic properties of cobalt-doped iron oxide nanoparticles prepared by solution combustion method for biomedical applications.

    PubMed

    Venkatesan, Kaliyamoorthy; Rajan Babu, Dhanakotti; Kavya Bai, Mane Prabhu; Supriya, Ravi; Vidya, Radhakrishnan; Madeswaran, Saminathan; Anandan, Pandurangan; Arivanandhan, Mukannan; Hayakawa, Yasuhiro

    2015-01-01

    Cobalt-doped iron oxide nanoparticles were prepared by solution combustion technique. The structural and magnetic properties of the prepared samples were also investigated. The average crystallite size of cobalt ferrite (CoFe2O4) magnetic nanoparticle was calculated using Scherrer equation, and it was found to be 16±5 nm. The particle size was measured by transmission electron microscope. This value was found to match with the crystallite size calculated by Scherrer equation corresponding to the prominent intensity peak (311) of X-ray diffraction. The high-resolution transmission electron microscope image shows clear lattice fringes and high crystallinity of cobalt ferrite magnetic nanoparticles. The synthesized magnetic nanoparticles exhibited the saturation magnetization value of 47 emu/g and coercivity of 947 Oe. The anti-microbial activity of cobalt ferrite nanoparticles showed better results as an anti-bacterial agent. The affinity constant was determined for the nanoparticles, and the cytotoxicity studies were conducted for the cobalt ferrite nanoparticles at different concentrations and the results are discussed.

  15. Passing through the renal clearance barrier: toward ultrasmall sizes with stable ligands for potential clinical applications

    PubMed Central

    Zhang, Xiao-Dong; Yang, Jiang; Song, Sha-Sha; Long, Wei; Chen, Jie; Shen, Xiu; Wang, Hao; Sun, Yuan-Ming; Liu, Pei-Xun; Fan, Saijun

    2014-01-01

    The use of nanoparticles holds promise for medical applications, such as X-ray imaging, photothermal therapy and radiotherapy. However, the in vivo toxicity of inorganic nanoparticles raises some concern regarding undesirable side effects which prevent their further medical application. Ultrasmall sub-5.5 nm particles can pass through the barrier for renal clearance, minimizing their toxicity. In this letter we address some recent interesting work regarding in vivo toxicity and renal clearance, and discuss the possible strategy of utilizing ultrasmall nanomaterials. We propose that small hydrodynamic sized nanoclusters can achieve both nontoxic and therapeutic clinical features. PMID:24812507

  16. Strong and moldable cellulose magnets with high ferrite nanoparticle content.

    PubMed

    Galland, Sylvain; Andersson, Richard L; Ström, Valter; Olsson, Richard T; Berglund, Lars A

    2014-11-26

    A major limitation in the development of highly functional hybrid nanocomposites is brittleness and low tensile strength at high inorganic nanoparticle content. Herein, cellulose nanofibers were extracted from wood and individually decorated with cobalt-ferrite nanoparticles and then for the first time molded at low temperature (<120 °C) into magnetic nanocomposites with up to 93 wt % inorganic content. The material structure was characterized by TEM and FE-SEM and mechanically tested as compression molded samples. The obtained porous magnetic sheets were further impregnated with a thermosetting epoxy resin, which improved the load-bearing functions of ferrite and cellulose material. A nanocomposite with 70 wt % ferrite, 20 wt % cellulose nanofibers, and 10 wt % epoxy showed a modulus of 12.6 GPa, a tensile strength of 97 MPa, and a strain at failure of ca. 4%. Magnetic characterization was performed in a vibrating sample magnetometer, which showed that the coercivity was unaffected and that the saturation magnetization was in proportion with the ferrite content. The used ferrite, CoFe2O4, is a magnetically hard material, demonstrated by that the composite material behaved as a traditional permanent magnet. The presented processing route is easily adaptable to prepare millimeter-thick and moldable magnetic objects. This suggests that the processing method has the potential to be scaled-up for industrial use for the preparation of a new subcategory of magnetic, low-cost, and moldable objects based on cellulose nanofibers. PMID:25331121

  17. Strong and moldable cellulose magnets with high ferrite nanoparticle content.

    PubMed

    Galland, Sylvain; Andersson, Richard L; Ström, Valter; Olsson, Richard T; Berglund, Lars A

    2014-11-26

    A major limitation in the development of highly functional hybrid nanocomposites is brittleness and low tensile strength at high inorganic nanoparticle content. Herein, cellulose nanofibers were extracted from wood and individually decorated with cobalt-ferrite nanoparticles and then for the first time molded at low temperature (<120 °C) into magnetic nanocomposites with up to 93 wt % inorganic content. The material structure was characterized by TEM and FE-SEM and mechanically tested as compression molded samples. The obtained porous magnetic sheets were further impregnated with a thermosetting epoxy resin, which improved the load-bearing functions of ferrite and cellulose material. A nanocomposite with 70 wt % ferrite, 20 wt % cellulose nanofibers, and 10 wt % epoxy showed a modulus of 12.6 GPa, a tensile strength of 97 MPa, and a strain at failure of ca. 4%. Magnetic characterization was performed in a vibrating sample magnetometer, which showed that the coercivity was unaffected and that the saturation magnetization was in proportion with the ferrite content. The used ferrite, CoFe2O4, is a magnetically hard material, demonstrated by that the composite material behaved as a traditional permanent magnet. The presented processing route is easily adaptable to prepare millimeter-thick and moldable magnetic objects. This suggests that the processing method has the potential to be scaled-up for industrial use for the preparation of a new subcategory of magnetic, low-cost, and moldable objects based on cellulose nanofibers.

  18. Core/Shell and High Aspect Ratio Magnetic Oxide Nanoparticles for Antenna Applications

    NASA Astrophysics Data System (ADS)

    Ekiert, Thomas F., Jr.; O'Malley, Matthew; Yocum, Brandon; Lippold, Jennifer; Lyle, Mallory; Griner, Angela; Flynn, Cory; Nickel, Anna; Alexander, Max D., Jr.

    2012-02-01

    Improved antenna gain, reduced antenna aperture size, and improved bandwidth are of interest to an increasingly mobile world. To obtain these improvements our efforts are directed at developing new magnetic oxide nanoparticle/polymer composites with modifiable permeability and permittivity and low electrical losses. Our approach consists of producing core/shell and shape controlled magnetic nanoparticles. Methods of synthesis utilize microwave and traditional heating to perform hydrothermal and solvothermal reactions. Decomposition of metal acetylacetonates is performed using various alcohols resulting in spherical nanoparticles with diameters of 8-16 nm and 3-7 nm for Fe3O4 and CoFe2O4, respectively. Microwave methods result in similar particles, but are produced in an hour or less as compared to 48 hrs via the traditional solvothermal method. Successive growths are used to produce larger monolithic particles as well as core/shell systems where exchange coupling between the core and shell is observed. Hexaferrite particles have been produced via hydrothermal synthesis, while high aspect ratio Fe3O4 nanoparticles ( 10-100 nm) produced via hydrothermal synthesis result in nanoneedles with high μr.

  19. High longitudinal relaxivity of ultra-small gadolinium oxide prepared by microsecond laser ablation in diethylene glycol

    NASA Astrophysics Data System (ADS)

    Luo, Ningqi; Tian, Xiumei; Xiao, Jun; Hu, Wenyong; Yang, Chuan; Li, Li; Chen, Dihu

    2013-04-01

    Ultra-small gadolinium oxide (Gd2O3) can be used as T1-weighted Magnetic Resonance Imaging (MRI) contrast agent own to its high longitudinal relaxivity (r1) and has attracted intensive attention in these years. In this paper, ultra-small Gd2O3 nanoparticles of 3.8 nm in diameter have been successfully synthesized by a microsecond laser ablating a gadolinium (Gd) target in diethylene glycol (DEG). The growth inhibition effect induced by the large viscosity of DEG makes it possible to synthesize ultra-small Gd2O3 by laser ablation in DEG. The r1 value and T1-weighted MR images are measured by a 3.0 T MRI spectroscope. The results show these nanoparticles with a high r1 value of 9.76 s-1 mM-1 to be good MRI contrast agents. We propose an explanation for the high r1 value of ultra-small Gd2O3 by considering the decreasing factor (surface to volume ratio of the nanoparticles, S/V) and the increasing factor (water hydration number of the Gd3+ on Gd2O3 surface, q), which offer a new look into the relaxivity studies of MRI contrast agents. Our research provides a new approach to preparing ultra-small Gd2O3 of high r1 value by laser ablation in DEG and develops the understanding of high relaxivity of ultra-small Gd2O3 MRI contrast agents.

  20. Hemolysin coregulated protein 1 as a molecular gluing unit for the assembly of nanoparticle hybrid structures.

    PubMed

    Pham, Tuan Anh; Schreiber, Andreas; Sturm Née Rosseeva, Elena V; Schiller, Stefan; Cölfen, Helmut

    2016-01-01

    Hybrid nanoparticle (NP) structures containing organic building units such as polymers, peptides, DNA and proteins have great potential in biosensor and electronic applications. The nearly free modification of the polymer chain, the variation of the protein and DNA sequence and the implementation of functional moieties provide a great platform to create inorganic structures of different morphology, resulting in different optical and magnetic properties. Nevertheless, the design and modification of a protein structure with functional groups or sequences for the assembly of biohybrid materials is not trivial. This is mainly due to the sensitivity of its secondary, tertiary and quaternary structure to the changes in the interaction (e.g., hydrophobic, hydrophilic, electrostatic, chemical groups) between the protein subunits and the inorganic material. Here, we use hemolysin coregulated protein 1 (Hcp1) from Pseudomonas aeruginosa as a building and gluing unit for the formation of biohybrid structures by implementing cysteine anchoring points at defined positions on the protein rim (Hcp1_cys3). We successfully apply the Hcp1_cys3 gluing unit for the assembly of often linear, hybrid structures of plasmonic gold (Au NP), magnetite (Fe3O4 NP), and cobalt ferrite nanoparticles (CoFe2O4 NP). Furthermore, the assembly of Au NPs into linear structures using Hcp1_cys3 is investigated by UV-vis spectroscopy, TEM and cryo-TEM. One key parameter for the formation of Au NP assembly is the specific ionic strength in the mixture. The resulting network-like structure of Au NPs is characterized by Raman spectroscopy, showing surface-enhanced Raman scattering (SERS) by a factor of 8·10(4) and a stable secondary structure of the Hcp1_cys3 unit. In order to prove the catalytic performance of the gold hybrid structures, they are used as a catalyst in the reduction reaction of 4-nitrophenol showing similar catalytic activity as the pure Au NPs. To further extend the functionality of the

  1. Hemolysin coregulated protein 1 as a molecular gluing unit for the assembly of nanoparticle hybrid structures

    PubMed Central

    Pham, Tuan Anh; Schreiber, Andreas; Sturm (née Rosseeva), Elena V

    2016-01-01

    Summary Hybrid nanoparticle (NP) structures containing organic building units such as polymers, peptides, DNA and proteins have great potential in biosensor and electronic applications. The nearly free modification of the polymer chain, the variation of the protein and DNA sequence and the implementation of functional moieties provide a great platform to create inorganic structures of different morphology, resulting in different optical and magnetic properties. Nevertheless, the design and modification of a protein structure with functional groups or sequences for the assembly of biohybrid materials is not trivial. This is mainly due to the sensitivity of its secondary, tertiary and quaternary structure to the changes in the interaction (e.g., hydrophobic, hydrophilic, electrostatic, chemical groups) between the protein subunits and the inorganic material. Here, we use hemolysin coregulated protein 1 (Hcp1) from Pseudomonas aeruginosa as a building and gluing unit for the formation of biohybrid structures by implementing cysteine anchoring points at defined positions on the protein rim (Hcp1_cys3). We successfully apply the Hcp1_cys3 gluing unit for the assembly of often linear, hybrid structures of plasmonic gold (Au NP), magnetite (Fe3O4 NP), and cobalt ferrite nanoparticles (CoFe2O4 NP). Furthermore, the assembly of Au NPs into linear structures using Hcp1_cys3 is investigated by UV–vis spectroscopy, TEM and cryo-TEM. One key parameter for the formation of Au NP assembly is the specific ionic strength in the mixture. The resulting network-like structure of Au NPs is characterized by Raman spectroscopy, showing surface-enhanced Raman scattering (SERS) by a factor of 8·104 and a stable secondary structure of the Hcp1_cys3 unit. In order to prove the catalytic performance of the gold hybrid structures, they are used as a catalyst in the reduction reaction of 4-nitrophenol showing similar catalytic activity as the pure Au NPs. To further extend the functionality

  2. Evolution of the magnetic structure with chemical composition in spinel iron oxide nanoparticles.

    PubMed

    Muscas, G; Yaacoub, N; Concas, G; Sayed, F; Sayed Hassan, R; Greneche, J M; Cannas, C; Musinu, A; Foglietti, V; Casciardi, S; Sangregorio, C; Peddis, D

    2015-08-28

    Magnetic properties of iron oxide nanoparticles with spinel structure are strictly related to a complex interplay between cationic distribution and the presence of a non-collinear spin structure (spin canting). With the aim to gain better insight into the effect of the magnetic structure on magnetic properties, in this paper we investigated a family of small crystalline ferrite nanoparticles of the formula CoxNi1-xFe2O4 (0 ≤x≤ 1) having equal size (≈4.5 nm) and spherical-like shape. The field dependence of magnetization at low temperatures indicated a clear increase of magnetocrystalline anisotropy and saturation magnetization (higher than the bulk value for CoFe2O4: ∼130 A m(2) kg(-1)) with the increase of cobalt content. The magnetic structure of nanoparticles has been investigated by Mössbauer spectroscopy under an intense magnetic field (8 T) at a low temperature (10 K). The magnetic properties have been explained in terms of an evolution of the magnetic structure with the increase of cobalt content. In addition a direct correlation between cationic distribution and spin canting has been proposed, explaining the presence of a noncollinear spin structure in terms of superexchange interaction energy produced by the average cationic distribution and vacancies in the spinel structure.

  3. Sol–gel hydrothermal synthesis of strontium hexaferrite nanoparticles and the relation between their crystal structure and high coercivity properties

    NASA Astrophysics Data System (ADS)

    Hue Dang, Thi Minh; Dung Trinh, Viet; Huan Bui, Doan; Huong Phan, Manh; Chinh Huynh, Dang

    2012-06-01

    Hard magnetic strontium hexaferrite SrFe12O19 nanoparticles were synthesized by the sol–gel hydrothermal method. The factors affecting the synthesized process, such as the mole proportion of the reactants, pH, temperature, the hydrothermal conditions and the calcination process, have been investigated. The crystal structures of these materials were refined by Rietveld method. The obtained materials have single crystal phase, equal nano-size, plate shape and high anisotropy. The high magnetic coercivity of 6.3 kOe with the magnetization at 11.1 kOe of 66 emu g‑1 at room temperature was observed for the strontium hexaferrite nanoparticles. For other nanoparticles (SrLnxFe12-xO19 and SrFe12O19/CoFe2O4) synthesized on the basis of SrFe12O19 the complex completion of the crystal structure distortion and the interaction between magnetic phases were observed.

  4. Tuning magnetoelectric coupling using porosity in multiferroic nanocomposites of ALD-grown Pb(Zr,Ti)O3 and templated mesoporous CoFe2O4

    NASA Astrophysics Data System (ADS)

    Chien, Diana; Buditama, Abraham N.; Schelhas, Laura T.; Kang, Hye Yeon; Robbennolt, Shauna; Chang, Jane P.; Tolbert, Sarah H.

    2016-09-01

    In this manuscript, we examine ways to create multiferroic composites with controlled nanoscale architecture. We accomplished this by uniformly depositing piezoelectric lead zirconate titanate (PZT) into templated mesoporous, magnetostrictive cobalt ferrite (CFO) thin films to form nanocomposites in which strain can be transferred at the interface between the two materials. To study the magnetoelectric coupling, the nanostructure was electrically poled ex situ prior to magnetic measurements. No samples showed a change in in-plane magnetization as a function of voltage due to substrate clamping. Out-of-plane changes were observed, but contrary to expectations based on total PZT volume fraction, mesoporous CFO samples partially filled with PZT showed more change in out-of-plane magnetization than the sample with fully filled pores. This result suggests that residual porosity in the composite adds mechanical flexibility and results in greater magnetoelectric coupling.

  5. Targeted and controlled anticancer drug delivery and release with magnetoelectric nanoparticles

    NASA Astrophysics Data System (ADS)

    Rodzinski, Alexandra; Guduru, Rakesh; Liang, Ping; Hadjikhani, Ali; Stewart, Tiffanie; Stimphil, Emmanuel; Runowicz, Carolyn; Cote, Richard; Altman, Norman; Datar, Ram; Khizroev, Sakhrat

    2016-02-01

    It is a challenge to eradicate tumor cells while sparing normal cells. We used magnetoelectric nanoparticles (MENs) to control drug delivery and release. The physics is due to electric-field interactions (i) between MENs and a drug and (ii) between drug-loaded MENs and cells. MENs distinguish cancer cells from normal cells through the membrane’s electric properties; cancer cells have a significantly smaller threshold field to induce electroporation. In vitro and in vivo studies (nude mice with SKOV-3 xenografts) showed that (i) drug (paclitaxel (PTX)) could be attached to MENs (30-nm CoFe2O4@BaTiO3 nanostructures) through surface functionalization to avoid its premature release, (ii) drug-loaded MENs could be delivered into cancer cells via application of a d.c. field (~100 Oe), and (iii) the drug could be released off MENs on demand via application of an a.c. field (~50 Oe, 100 Hz). The cell lysate content was measured with scanning probe microscopy and spectrophotometry. MENs and control ferromagnetic and polymer nanoparticles conjugated with HER2-neu antibodies, all loaded with PTX were weekly administrated intravenously. Only the mice treated with PTX-loaded MENs (15/200 μg) in a field for three months were completely cured, as confirmed through infrared imaging and post-euthanasia histology studies via energy-dispersive spectroscopy and immunohistochemistry.

  6. Targeted and controlled anticancer drug delivery and release with magnetoelectric nanoparticles

    PubMed Central

    Rodzinski, Alexandra; Guduru, Rakesh; Liang, Ping; Hadjikhani, Ali; Stewart, Tiffanie; Stimphil, Emmanuel; Runowicz, Carolyn; Cote, Richard; Altman, Norman; Datar, Ram; Khizroev, Sakhrat

    2016-01-01

    It is a challenge to eradicate tumor cells while sparing normal cells. We used magnetoelectric nanoparticles (MENs) to control drug delivery and release. The physics is due to electric-field interactions (i) between MENs and a drug and (ii) between drug-loaded MENs and cells. MENs distinguish cancer cells from normal cells through the membrane’s electric properties; cancer cells have a significantly smaller threshold field to induce electroporation. In vitro and in vivo studies (nude mice with SKOV-3 xenografts) showed that (i) drug (paclitaxel (PTX)) could be attached to MENs (30-nm CoFe2O4@BaTiO3 nanostructures) through surface functionalization to avoid its premature release, (ii) drug-loaded MENs could be delivered into cancer cells via application of a d.c. field (~100 Oe), and (iii) the drug could be released off MENs on demand via application of an a.c. field (~50 Oe, 100 Hz). The cell lysate content was measured with scanning probe microscopy and spectrophotometry. MENs and control ferromagnetic and polymer nanoparticles conjugated with HER2-neu antibodies, all loaded with PTX were weekly administrated intravenously. Only the mice treated with PTX-loaded MENs (15/200 μg) in a field for three months were completely cured, as confirmed through infrared imaging and post-euthanasia histology studies via energy-dispersive spectroscopy and immunohistochemistry. PMID:26875783

  7. Micrometric periodic assembly of magnetotactic bacteria and magnetic nanoparticles using audio tapes

    NASA Astrophysics Data System (ADS)

    Godoy, M.; Moreno, A. J.; Jorge, G. A.; Ferrari, H. J.; Antonel, P. S.; Mietta, J. L.; Ruiz, M.; Negri, R. M.; Pettinari, M. J.; Bekeris, V.

    2012-02-01

    We report micrometric periodic assembly of live and dead magnetotactic bacteria, Magnetospirillum magneticum AMB-1, which synthesize chains of magnetic nanoparticles inside their bodies, and of superparamagnetic Fe3O4 and ferromagnetic CoFe2O4 nanoparticles in aqueous suspensions using periodically magnetized audio tapes. The distribution of the stray magnetic field at the surface of the tapes was determined analytically and experimentally by magneto-optic imaging. Calculations showed that the magnetic field close to the tape surface was of the order of 100 mT, and the magnetic field gradient was larger than 1 T mm-1. Drops of aqueous solutions were deposited on the tapes, and bacteria and particles were trapped at locations where magnetic energy is minimized, as observed using conventional optical microscopy. Suspensions of M. magneticum AMB-1 treated with formaldehyde and kanamycin were studied, and patterns of trapped dead bacteria indicated that magnetic forces dominate over self-propelling forces in these experiments, in accordance with calculated values. The behavior of the different types of samples is discussed.

  8. Ultrasmall Carbide Nanospheres - Formation and Electronic Properties

    NASA Astrophysics Data System (ADS)

    Reinke, Petra; Monazami, Ehsan; McClimon, John

    2015-03-01

    Metallic nanoparticles are highly coveted but are subject to rapid Ostwald ripening even at moderate temperatures limiting study of their properties. Ultrasmall transition metal carbide ``nanospheres'' are synthesized by a solid-state reaction between fullerene as carbon scaffold, and a W surface. This produces nanospheres with a narrow size distribution below 2.5 nm diameter. The nanosphere shape is defined by the scaffold and densely packed arrays can be achieved. The metal-fullerene reaction is temperature driven and progresses through an intermediate semiconducting phase until the fully metallic nanospheres are created at about 350 C. The reaction sequence is observed with STM, and STS maps yield the local density of states. The reaction presumably progresses by stepwise introduction of W-atoms in the carbon scaffold. The results of high resolution STM/STS in combination with DFT calculations are used to unravel the reaction mechanism. We will discuss the transfer of this specific reaction mechanism to other transition metal carbides. The nanospheres are an excellent testbed for the physics and chemistry of highly curved surfaces.

  9. Fabrication of Porous Anodic Alumina with Ultrasmall Nanopores

    NASA Astrophysics Data System (ADS)

    Ding, Gu Qiao; Yang, Rong; Ding, Jian Ning; Yuan, Ning Yi; Zhu, Yuan Yuan

    2010-08-01

    Anodization of Al foil under low voltages of 1-10 V was conducted to obtain porous anodic aluminas (PAAs) with ultrasmall nanopores. Regular nanopore arrays with pore diameter 6-10 nm were realized in four different electrolytes under 0-30°C according to the AFM, FESEM, TEM images and current evolution curves. It is found that the pore diameter and interpore distance, as well as the barrier layer thickness, are not sensitive to the applied potentials and electrolytes, which is totally different from the rules of general PAA fabrication. The brand-new formation mechanism has been revealed by the AFM study on the samples anodized for very short durations of 2-60 s. It is discovered for the first time that the regular nanoparticles come into being under 1-10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultrasmall nanopores. Under higher potentials from 10 to 40 V, the surface nanoparticles will be less and less and nanopores transform into general PAAs.

  10. Tuning the magnetic properties of Co-ferrite nanoparticles through the 1,2-hexadecanediol concentration in the reaction mixture.

    PubMed

    Moya, Carlos; Morales, María del Puerto; Batlle, Xavier; Labarta, Amílcar

    2015-05-21

    This work reports on the effect of the 1,2-hexadecanediol content on the structural and magnetic properties of CoFe2O4 nanoparticles synthesized by thermal decomposition of metal-organic precursors in 1-octadecene. Although pseudo-spherical particles having an average size of about 8 nm and similar stoichiometry have been observed in all studied samples, a high level of variability in the crystal quality and, in turn, in the magnetic properties has been found as a function of the amount of 1,2-hexadecanediol added to the reaction mixture. The magnetic study reveals that samples progress from glassy magnetic behavior to bulk-like, ferrimagnetic order as the crystal quality improves. The analysis of the reaction mixtures by Fourier transform infrared spectroscopy at various stages of the reaction shows the key role of the 1,2-hexadecanediol in favoring the decomposition of the metal-organic precursor, formation of an intermediate Co(2+)Fe(3+)-oleate complex and, finally, the nucleation of nanoparticles at lower temperatures.

  11. Surface spin-glass in cobalt ferrite nanoparticles dispersed in silica matrix

    NASA Astrophysics Data System (ADS)

    Zeb, F.; Sarwer, W.; Nadeem, K.; Kamran, M.; Mumtaz, M.; Krenn, H.; Letofsky-Papst, I.

    2016-06-01

    Surface effects in cobalt ferrite (CoFe2O4) nanoparticles dispersed in a silica (SiO2) matrix were studied by using AC and DC magnetization. Nanoparticles with different concentration of SiO2 were synthesized by using sol-gel method. Average crystallite size lies in the range 25-34 nm for different SiO2 concentration. TEM image showed that particles are spherical and elongated in shape. Nanoparticles with higher concentration of SiO2 exhibit two peaks in the out-of-phase ac-susceptibility. First peak lies in the high temperature regime and corresponds to average blocking temperature of the nanoparticles. Second peak lies in the low temperature regime and is attributed to surface spin-glass freezing in these nanoparticles. Low temperature peak showed SiO2 concentration dependence and was vanished for large uncoated nanoparticles. The frequency dependence of the AC-susceptibility of low temperature peak was fitted with dynamic scaling law which ensures the presence of spin-glass behavior. With increasing applied DC field, the low temperature peak showed less shift as compared to blocking peak, broaden, and decreased in magnitude which also signifies its identity as spin-glass peak for smaller nanoparticles. M-H loops showed the presence of more surface disorder in nanoparticles dispersed in 60% SiO2 matrix. All these measurements revealed that surface effects become strengthen with increasing SiO2 matrix concentration and surface spins freeze in to spin-glass state at low temperatures.

  12. A study of the properties of SrFe12-xCoxO19 nanoparticles

    NASA Astrophysics Data System (ADS)

    Mousavi Ghahfarokhi, S. E.; Ranjbar, F.; Zargar Shoushtari, M.

    2014-01-01

    In this paper, the nanoparticles of SrFe12-xCoxO19 (x=0-2) were synthesized via the sol-gel technique. The XRD results showed that all samples with x≤0.5 are single-phase. It seems that the Fe3+ ions are substituted by Co2+ ions in the crystallography sites of the SrFe12O19 structure, but for the x>0.5 cases, the phase of CoFe2O4 is materialized in the samples. The DC electrical resistivity decreases with the increase of cobalt content up to level of x=0.5, but it increases on further addition of cobalt. We found that the dielectric constant and the dielectric loss for samples with x=1 and 1.2 into the pure sample (SrFe12O19), decrease as the Co2+ content increases. The variation of AC conductivity (σac) with frequency ranging from 500 Hz to 200 KHz shows that electrical conductivity in these ferrites is mainly due to the electron hopping mechanism.

  13. The role of annealing temperature and bio template (egg white) on the structural, morphological and magnetic properties of manganese substituted MFe2O4 (M=Zn, Cu, Ni, Co) nanoparticles

    NASA Astrophysics Data System (ADS)

    Ranjith Kumar, E.; Jayaprakash, R.; Kumar, Sanjay

    2014-02-01

    Manganese substituted ferrites (ZnFe2O4, CuFe2O4, NiFe2O4 and CoFe2O4) have been prepared in the bio template medium by using a simple evaporation method. The annealing temperature plays an important position on changing particle size and morphology of the mixed ferrite nanoparticles were found out by X-ray diffraction, transmission electron microscopy and scanning electron microscopy methods. The role of manganese substitution in the mixed ferrite nanoparticles were also analyzed for different annealing temperature. The substitution of Mn also creates a vital change in magnetic properties which is studied by using vibrating sample magnetometer (VSM). These spinel ferrites are decomposed to α-Fe2O3 after annealing above 550 °C in air. However, α-Fe2O3 phase was slowly vanished after ferrites annealing above 900 °C. The effect of this secondary phase on the structural change and magnetic properties of the mixed ferrite nanoparticles is discussed.

  14. Use of oleic-acid functionalized nanoparticles for the magnetic solid-phase microextraction of alkylphenols in fruit juices using liquid chromatography-tandem mass spectrometry.

    PubMed

    Viñas, Pilar; Pastor-Belda, Marta; Torres, Aitor; Campillo, Natalia; Hernández-Córdoba, Manuel

    2016-05-01

    Magnetic nanoparticles of cobalt ferrite with oleic acid as the surfactant (CoFe2O4/oleic acid) were used as sorbent material for the determination of alkylphenols in fruit juices. High sensitivity and specificity were achieved by liquid chromatography and detection using both diode-array (DAD) and electrospray-ion trap-tandem mass spectrometry (ESI-IT-MS/MS) in the selected reaction monitoring (SRM) mode of the negative fragment ions for alkylphenols (APs) and in positive mode for ethoxylate APs (APEOs). The optimized conditions for the different variables influencing the magnetic separation procedure were: mass of magnetic nanoparticles, 50mg, juice volume, 10mL diluted to 25mL with water, pH 6, stirring for 10min at room temperature, separation with an external neodymium magnet, desorption with 3mL of methanol and orbital shaking for 5min. The enriched organic phase was evaporated and reconstituted with 100µL acetonitrile before injecting 30µL into a liquid chromatograph with a mobile phase composed of acetonitrile/0.1% (v/v) formic acid under gradient elution. Quantification limits were in the range 3.6 to 125ngmL(-1). The recoveries obtained were in the 91-119% range, with RSDs lower than 14%. The ESI-MS/MS spectra permitted the correct identification of both APs and APEOs in the fruit juice samples. PMID:26946030

  15. Facile Syntheses of Monodisperse Ultra-Small Au Clusters

    SciTech Connect

    Bertino, Massimo F.; Sun, Zhong-Ming; Zhang, Rui; Wang, Lai S.

    2006-11-02

    During our effort to synthesize the tetrahedral Au20 cluster, we found a facile synthetic route to prepare monodisperse suspensions of ultra-small Au clusters AuN (N<12) using diphosphine ligands. In our monophasic and single-pot synthesis, a Au precursor ClAu(I)PPh3 and a bidentate phosphine ligand P(Ph)2(CH2)MP(Ph)2 (Ph = phenyl) are dissolved in an organic solvent. Au(I) is reduced slowly by a borane-tert-butylamine complex to form Au clusters coordinated by the diphosphine ligand. The Au clusters are characterized by both high resolution mass spectrometry and UV-Vis absorption spectroscopy. We found that the mean cluster size obtained depends on the chain length M of the ligand. In particular, a single monodispersed Au11 cluster is obtained with the P(Ph)2(CH2)3P(Ph)2 ligand, whereas P(Ph)2(CH2)MP(Ph)2 ligands with M = 5 and 6 yield Au10 and Au8 clusters. The simplicity of our synthetic method makes it suitable for large-scale production of nearly monodisperse ultrasmall Au clusters. It is suggested that diphosphines provide a set of flexible ligands to allow size-controlled synthesis of Au nanoparticles.

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

    PubMed Central

    2011-01-01

    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

  17. Well-Combined Magnetically Separable Hybrid Cobalt Ferrite/Nitrogen-Doped Graphene as Efficient Catalyst with Superior Performance for Oxygen Reduction Reaction.

    PubMed

    Lu, Lei; Hao, Qingli; Lei, Wu; Xia, Xifeng; Liu, Peng; Sun, Dongping; Wang, Xin; Yang, Xujie

    2015-11-18

    Catalysts with low-cost, high activity and stability toward oxygen reduction reaction (ORR) are extremely desirable, but its development still remains a great challenge. Here, a novel magnetically separable hybrid of multimetal oxide, cobalt ferrite (CoFe2O4), anchored on nitrogen-doped reduced graphene oxide (CoFe2O4/NG) is prepared via a facile solvothermal method followed by calcination at 500 °C. The structure of CoFe2O4/NG and the interaction of both components are analyzed by several techniques. The possible formation of Co/Fe-N interaction in the CoFe2O4/NG catalyst is found. As a result, the well-combination of CoFe2O4 nanoparticles with NG and its improved crystallinity lead to a synergistic and efficient catalyst with high performance to ORR through a four-electron-transfer process in alkaline medium. The CoFe2O4/NG exhibits particularly comparable catalytic activity as commercial Pt/C catalyst, and superior stability against methanol oxidation and CO poisoning. Meanwhile, it has been proved that both nitrogen doping and the spinel structure of CoFe2O4 can have a significant contribution to the catalytic activity by contrast experiments. Multimetal oxide hybrid demonstrates better catalysis to ORR than a single metal oxide hybrid. All results make the low-cost and magnetically separable CoFe2O4/NG a promising alternative for costly platinum-based ORR catalyst in fuel cells and metal-air batteries. PMID:26390018

  18. On the magnetic anisotropy and nuclear relaxivity effects of Co and Ni doping in iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Orlando, T.; Albino, M.; Orsini, F.; Innocenti, C.; Basini, M.; Arosio, P.; Sangregorio, C.; Corti, M.; Lascialfari, A.

    2016-04-01

    We report a systematic experimental study of the evolution of the magnetic and relaxometric properties as a function of metal (Co, Ni) doping in iron oxide nanoparticles. A set of five samples, having the same size and ranging from stoichiometric cobalt ferrite (CoFe2O4) to stoichiometric nickel ferrite (NiFe2O4) with intermediate doping steps, was ad hoc synthesized. Using both DC and AC susceptibility measurements, the evolution of the magnetic anisotropy depending on the doping is qualitatively discussed. In particular, we observed that the height of the magnetic anisotropy barrier is directly proportional to the amount of Co, while the Ni has an opposite effect. By Nuclear Magnetic Resonance Dispersion (NMR-D) experiments, the experimental longitudinal r1 and transverse r2 relaxivity profiles were obtained, and the heuristic theory of Roch et al. was used to analyze the data of both r1 and, for the first time, r2. While the experimental and fitting results obtained from r1 profiles were satisfying and confirmed the anisotropy trend, the model applied to r2 hardly explains the experimental findings.

  19. Enhancement of specific absorption rate by exchange coupling of the core-shell structure of magnetic nanoparticles for magnetic hyperthermia

    NASA Astrophysics Data System (ADS)

    Phadatare, M. R.; Meshram, J. V.; Gurav, K. V.; Hyeok Kim, Jin; Pawar, S. H.

    2016-03-01

    Conversion of electromagnetic energy into heat by nanoparticles (NPs) has the potential to be a powerful, non-invasive technique for biomedical applications such as magnetic fluid hyperthermia, drug release, disease treatment and remote control of single cell functions, but poor conversion efficiencies have hindered practical applications so far. In this paper, an attempt has been made to increase the efficiency of magnetic thermal induction by NPs. To increase the efficiency of magnetic thermal induction by NPs, one can take advantage of the exchange coupling between a magnetically hard core and magnetically soft shell to tune the magnetic properties of the NP and maximize the specific absorption rate, which is the gauge of conversion efficiency. In order to examine the tunability of magnetocrystalline anisotropy and its magnetic heating power, a representative magnetically hard material (CoFe2O4) has been coupled to a soft material (Ni0.5Zn0.5Fe2O4). The synthesized NPs show specific absorption rates that are of an order of magnitude larger than the conventional one.

  20. Magneto-electric Nanoparticles to Enable Field-controlled High-Specificity Drug Delivery to Eradicate Ovarian Cancer Cells

    NASA Astrophysics Data System (ADS)

    Guduru, Rakesh; Liang, Ping; Runowicz, Carolyn; Nair, Madhavan; Atluri, Venkata; Khizroev, Sakhrat

    2013-10-01

    The nanotechnology capable of high-specificity targeted delivery of anti-neoplastic drugs would be a significant breakthrough in Cancer in general and Ovarian Cancer in particular. We addressed this challenge through a new physical concept that exploited (i) the difference in the membrane electric properties between the tumor and healthy cells and (ii) the capability of magneto-electric nanoparticles (MENs) to serve as nanosized converters of remote magnetic field energy into the MENs' intrinsic electric field energy. This capability allows to remotely control the membrane electric fields and consequently trigger high-specificity drug uptake through creation of localized nano-electroporation sites. In in-vitro studies on human ovarian carcinoma cell (SKOV-3) and healthy cell (HOMEC) lines, we applied a 30-Oe d.c. field to trigger high-specificity uptake of paclitaxel loaded on 30-nm CoFe2O4@BaTiO3 MENs. The drug penetrated through the membrane and completely eradicated the tumor within 24 hours without affecting the normal cells.

  1. Developing a Millifluidic Platform for the Synthesis of Ultrasmall Nanoclusters: Ultrasmall Copper Nanoclusters as a Case Study

    SciTech Connect

    Biswas, Sanchita; Miller, Jeffrey T.; Li, Yuehao; Nandakumar, Krishnaswamy; Kumar, Challa S.S.R.

    2012-02-02

    The future of lab-on-a-chip devices for the synthesis of nanomaterials hinges on the successful development of high-throughput methods with better control over their size. While significant effort in this direction mainly focuses on developing “difficult to fabricate” complex microfluidic reactors, scant attention has been paid to the “easy to fabricate” and simple millifluidic systems that could provide the required control as well as high throughput. By utilizing numerical simulation of fluids within the millifluidic space at different flow rates, the results presented here show velocity profiles and residence time distributions similar to the case of microfluidics. By significantly reducing the residence time and residence time distribution, a continuous flow synthesis of ultrasmall copper nanoclusters (UCNCs) with exceptional colloidal stability is achieved. In-situ synchrotron-radiation-based X-ray absorption spectroscopy (XAS) reveal that the as-prepared clusters are about 1 nm, which is further supported by transmission electron microscopy and UV–vis spectroscopy studies. The clusters reported here are the smallest ever produced using a lab-on-a-chip platform. When supported on silica, they are found to efficiently catalyze C–H oxidation reactions, hitherto unknown to be catalyzed by Cu. This work suggests that a millifluidic platform can be an inexpensive, versatile, easy-to-use, and powerful tool for nanoparticle synthesis in general, and more specifically for ultrasmall nanoclusters (UNCs).

  2. High longitudinal relaxivity of ultra-small gadolinium oxide prepared by microsecond laser ablation in diethylene glycol

    SciTech Connect

    Luo Ningqi; Xiao Jun; Hu Wenyong; Chen Dihu; Tian Xiumei; Yang Chuan; Li Li

    2013-04-28

    Ultra-small gadolinium oxide (Gd{sub 2}O{sub 3}) can be used as T{sub 1}-weighted Magnetic Resonance Imaging (MRI) contrast agent own to its high longitudinal relaxivity (r{sub 1}) and has attracted intensive attention in these years. In this paper, ultra-small Gd{sub 2}O{sub 3} nanoparticles of 3.8 nm in diameter have been successfully synthesized by a microsecond laser ablating a gadolinium (Gd) target in diethylene glycol (DEG). The growth inhibition effect induced by the large viscosity of DEG makes it possible to synthesize ultra-small Gd{sub 2}O{sub 3} by laser ablation in DEG. The r{sub 1} value and T{sub 1}-weighted MR images are measured by a 3.0 T MRI spectroscope. The results show these nanoparticles with a high r{sub 1} value of 9.76 s{sup -1} mM{sup -1} to be good MRI contrast agents. We propose an explanation for the high r{sub 1} value of ultra-small Gd{sub 2}O{sub 3} by considering the decreasing factor (surface to volume ratio of the nanoparticles, S/V) and the increasing factor (water hydration number of the Gd{sup 3+} on Gd{sub 2}O{sub 3} surface, q), which offer a new look into the relaxivity studies of MRI contrast agents. Our research provides a new approach to preparing ultra-small Gd{sub 2}O{sub 3} of high r{sub 1} value by laser ablation in DEG and develops the understanding of high relaxivity of ultra-small Gd{sub 2}O{sub 3} MRI contrast agents.

  3. Ultra-small particles of iron oxide as peroxidase for immunohistochemical detection

    NASA Astrophysics Data System (ADS)

    Wu, Yihang; Song, Mengjie; Xin, Zhuang; Zhang, Xiaoqing; Zhang, Yu; Wang, Chunyu; Li, Suyi; Gu, Ning

    2011-06-01

    Dimercaptosuccinic acid (DMSA) modified ultra-small particles of iron oxide (USPIO) were synthesized through a two-step process. The first step: oleic acid (OA) capped Fe3O4 (OA-USPIO) were synthesized by a novel oxidation coprecipitation method in H2O/DMSO mixing system, where DMSO acts as an oxidant simultaneously. The second step: OA was replaced by DMSA to obtain water-soluble nanoparticles. The as-synthesized nanoparticles were characterized by TEM, FTIR, TGA, VSM, DLS, EDS and UV-vis. Hydrodynamic sizes and Peroxidase-like catalytic activity of the nanoparticles were investigated. The hydrodynamic sizes of the nanoparticles (around 24.4 nm) were well suited to developing stable nanoprobes for bio-detection. The kinetic studies were performed to quantitatively evaluate the catalytic ability of the peroxidase-like nanoparticles. The calculated kinetic parameters indicated that the DMSA-USPIO possesses high catalytic activity. Based on the high activity, immunohistochemical experiments were established: using low-cost nanoparticles as the enzyme instead of expensive HRP, Nimotuzumab was conjugated onto the surface of the nanoparticles to construct a kind of ultra-small nanoprobe which was employed to detect epidermal growth factor receptor (EGFR) over-expressed on the membrane of esophageal cancer cell. The proper sizes of the probes and the result of membranous immunohistochemical staining suggest that the probes can be served as a useful diagnostic reagent for bio-detection.

  4. Ultrasmall dopamine-coated nanogolds: preparation, characteristics, and CT imaging

    PubMed Central

    Yu, Yao; Wu, Youshen; Liu, JiaJun; Zhan, Yonghua; Wu, Daocheng

    2016-01-01

    ABSTRACT Water-dispersible ultrasmall nanogolds (WDU AuNPs) and their dopamine-coated nanogolds (WDU AuNPs@DPAs) were prepared by a reduction method with sodium borohydride as a reducing agent and a stabilised agent of 2-mercaptosuccinic acid in aqueous solution. The effects of these nanoparticles on computed tomography (CT) imaging were evaluated. The size distributions and Zeta potential of the nanoparticles were measured with a Malvern size analyser, and nanoparticle morphology was observed by transmission electron microscopy. These characteristics were confirmed by Fourier transform spectroscopy and ultraviolet/visible spectra. It was found that WDU AuNPs@DPAs were 5.4 nm in size with clear core–shell structure. The 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyltetrazolium bromide assay results showed that the WDU AuNPs and WDU AuNPs@DPAs were hypotoxic to different cells. The WDU AuNPs@DPAs showed a much longer circulation time and a larger CT attenuation coefficient than iohexol and could be excreted by the kidney and bladder. These nanoparticles showed considerable potential for future application in CT imaging. PMID:27366201

  5. Ultrasmall fluorescent ion-exchanging nanospheres containing selective ionophores.

    PubMed

    Xie, Xiaojiang; Mistlberger, Günter; Bakker, Eric

    2013-10-15

    We present a convenient precipitation procedure to fabricate ultrasmall fluorescent ion-selective nanosensors that operate on the basis of bulk ion-exchange sensing principles. The nanosphere matrix is composed of bis(2-ethylhexyl) sebacate (DOS) and a triblock copolymer Pluronic(®) F-127, which also functions as a surfactant to stabilize the nanoparticle. The particles can be prepared easily in large quantity without resorting to further complicated purification. Dynamic light scattering shows that these particles have a monodisperse size distribution with an average diameter of ∼40 nm, suggesting that the nanoparticles are among the smallest ionophore-based ion-selective nanosensors reported to date. A newly reported oxazinoindoline (Ox) as well as a Nile blue derivative (chromoionophore I) was used as a chromoionophore. Na(+)- and H(+)-selective nanospheres were characterized by absorbance and fluorescence spectroscopy. Owing to the very small size of the nanospheres, the suspension containing the particles is transparent. In the additional presence of the pH indicator HPTS, spectroscopic interrogation of pH and Na(+) in the same sample was demonstrated. As an example, the nanospheres were used to measure the Na(+) level in commercial mineral waters, and the results showed good agreement with atomic absorption spectroscopy (AAS).

  6. Synthesis of Ultrasmall Cu2 O Nanocubes and Octahedra with Tunable Sizes for Facet-Dependent Optical Property Examination.

    PubMed

    Ke, Wei-Hong; Hsia, Chi-Fu; Chen, Ying-Jui; Huang, Michael H

    2016-07-01

    Size-tunable small to ultrasmall Cu2 O nanocubes and octahedra are synthesized in aqueous solution without the introduction of any surfactant. These nanocrystals provide strong evidence of the existence of facet-dependent optical absorption properties of Cu2 O nanoparticles, showing nanocubes always have a more redshifted absorption band than that of octahedra having a similar volume by about 15 nm. PMID:27218827

  7. Atomic scale dynamics of ultrasmall germanium clusters

    PubMed Central

    Bals, S.; Van Aert, S.; Romero, C.P.; Lauwaet, K.; Van Bael, M.J.; Schoeters, B.; Partoens, B.; Yücelen, E.; Lievens, P.; Van Tendeloo, G.

    2012-01-01

    Starting from the gas phase, small clusters can be produced and deposited with huge flexibility with regard to composition, materials choice and cluster size. Despite many advances in experimental characterization, a detailed morphology of such clusters is still lacking. Here we present an atomic scale observation as well as the dynamical behaviour of ultrasmall germanium clusters. Using quantitative scanning transmission electron microscopy in combination with ab initio calculations, we are able to characterize the transition between different equilibrium geometries of a germanium cluster consisting of less than 25 atoms. Seven-membered rings, trigonal prisms and some smaller subunits are identified as possible building blocks that stabilize the structure. PMID:22692540

  8. Atomic scale dynamics of ultrasmall germanium clusters.

    PubMed

    Bals, S; Van Aert, S; Romero, C P; Lauwaet, K; Van Bael, M J; Schoeters, B; Partoens, B; Yücelen, E; Lievens, P; Van Tendeloo, G

    2012-06-12

    Starting from the gas phase, small clusters can be produced and deposited with huge flexibility with regard to composition, materials choice and cluster size. Despite many advances in experimental characterization, a detailed morphology of such clusters is still lacking. Here we present an atomic scale observation as well as the dynamical behaviour of ultrasmall germanium clusters. Using quantitative scanning transmission electron microscopy in combination with ab initio calculations, we are able to characterize the transition between different equilibrium geometries of a germanium cluster consisting of less than 25 atoms. Seven-membered rings, trigonal prisms and some smaller subunits are identified as possible building blocks that stabilize the structure.

  9. High β phase content in PVDF/CoFe2O4 nanocomposites induced by DC magnetic fields

    NASA Astrophysics Data System (ADS)

    Jiang, Shenglin; Wan, Hongyan; Liu, Huan; Zeng, Yike; Liu, Jianguo; Wu, Yunyi; Zhang, Guangzu

    2016-09-01

    Flexible ferroelectrics being exploited as energy harvesting and conversion materials are highly desirable for wearable and skin-mountable electronic devices. As one of the most typical ferroelectric polymers, poly(vinylidene fluoride) (PVDF) has been widely used in modern electronic systems and devices, whose ferroelectric performance relies heavily on its β phase content. In this work, to achieve high-β-phase-content PVDF, we first introduced CoFe2O4 nanoparticles into PVDF. With the incorporation of CoFe2O4 nanoparticles used as an effective polymer nucleation agent, the percentage of the β phase in the PVDF has been significantly enhanced, e.g., 84% in the nanocomposite with 5 wt. % CoFe2O4 versus only 73% in the pure PVDF. In order to further increase the β phase content in PVDF, we subsequently proposed an easily realized strategy. By applying DC magnetic fields during the solution-casting process of the PVDF/CoFe2O4 nanocomposites, a further improved β phase content as high as 95% can be achieved. The further improvement of the β phase content is attributable to the tensile stress at the CoFe2O4/PVDF interfaces created by the coupling of magnetic field and CoFe2O4 by means of the magnetostriction effect. The high β-phase content makes the PVDF/CoFe2O4 nanocomposites a promising candidate for flexible and wearable electronic device applications.

  10. RGD-conjugated iron oxide magnetic nanoparticles for magnetic resonance imaging contrast enhancement and hyperthermia.

    PubMed

    Zheng, S W; Huang, M; Hong, R Y; Deng, S M; Cheng, L F; Gao, B; Badami, D

    2014-03-01

    The purpose of this study was to develop a specific targeting magnetic nanoparticle probe for magnetic resonance imaging and therapy in the form of local hyperthermia. Carboxymethyl dextran-coated ultrasmall superparamagnetic iron oxide nanoparticles with carboxyl groups were coupled to cyclic arginine-glycine-aspartic peptides for integrin α(v)β₃ targeting. The particle size, magnetic properties, heating effect, and stability of the arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide were measured. The arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide demonstrates excellent stability and fast magneto-temperature response. Magnetic resonance imaging signal intensity of Bcap37 cells incubated with arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide was significantly decreased compared with that incubated with plain ultrasmall superparamagnetic iron oxide. The preferential uptake of arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide by target cells was further confirmed by Prussian blue staining and confocal laser scanning microscopy.

  11. Ultrasmall all-optical plasmonic switch and its application to superresolution imaging

    NASA Astrophysics Data System (ADS)

    Wu, Hsueh-Yu; Huang, Yen-Ta; Shen, Po-Ting; Lee, Hsuan; Oketani, Ryosuke; Yonemaru, Yasuo; Yamanaka, Masahito; Shoji, Satoru; Lin, Kung-Hsuan; Chang, Chih-Wei; Kawata, Satoshi; Fujita, Katsumasa; Chu, Shi-Wei

    2016-04-01

    Because of their exceptional local-field enhancement and ultrasmall mode volume, plasmonic components can integrate photonics and electronics at nanoscale, and active control of plasmons is the key. However, all-optical modulation of plasmonic response with nanometer mode volume and unity modulation depth is still lacking. Here we show that scattering from a plasmonic nanoparticle, whose volume is smaller than 0.001 μm3, can be optically switched off with less than 100 μW power. Over 80% modulation depth is observed, and shows no degradation after repetitive switching. The spectral bandwidth approaches 100 nm. The underlying mechanism is suggested to be photothermal effects, and the effective single-particle nonlinearity reaches nearly 10‑9 m2/W, which is to our knowledge the largest record of metallic materials to date. As a novel application, the non-bleaching and unlimitedly switchable scattering is used to enhance optical resolution to λ/5 (λ/9 after deconvolution), with 100-fold less intensity requirement compared to similar superresolution techniques. Our work not only opens up a new field of ultrasmall all-optical control based on scattering from a single nanoparticle, but also facilitates superresolution imaging for long-term observation.

  12. Ultrasmall all-optical plasmonic switch and its application to superresolution imaging

    PubMed Central

    Wu, Hsueh-Yu; Huang, Yen-Ta; Shen, Po-Ting; Lee, Hsuan; Oketani, Ryosuke; Yonemaru, Yasuo; Yamanaka, Masahito; Shoji, Satoru; Lin, Kung-Hsuan; Chang, Chih-Wei; Kawata, Satoshi; Fujita, Katsumasa; Chu, Shi-Wei

    2016-01-01

    Because of their exceptional local-field enhancement and ultrasmall mode volume, plasmonic components can integrate photonics and electronics at nanoscale, and active control of plasmons is the key. However, all-optical modulation of plasmonic response with nanometer mode volume and unity modulation depth is still lacking. Here we show that scattering from a plasmonic nanoparticle, whose volume is smaller than 0.001 μm3, can be optically switched off with less than 100 μW power. Over 80% modulation depth is observed, and shows no degradation after repetitive switching. The spectral bandwidth approaches 100 nm. The underlying mechanism is suggested to be photothermal effects, and the effective single-particle nonlinearity reaches nearly 10−9 m2/W, which is to our knowledge the largest record of metallic materials to date. As a novel application, the non-bleaching and unlimitedly switchable scattering is used to enhance optical resolution to λ/5 (λ/9 after deconvolution), with 100-fold less intensity requirement compared to similar superresolution techniques. Our work not only opens up a new field of ultrasmall all-optical control based on scattering from a single nanoparticle, but also facilitates superresolution imaging for long-term observation. PMID:27063920

  13. Studying the effect of Zn-substitution on the magnetic and hyperthermic properties of cobalt ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Mameli, V.; Musinu, A.; Ardu, A.; Ennas, G.; Peddis, D.; Niznansky, D.; Sangregorio, C.; Innocenti, C.; Thanh, Nguyen T. K.; Cannas, C.

    2016-05-01

    The possibility to finely control nanostructured cubic ferrites (MIIFe2O4) paves the way to design materials with the desired magnetic properties for specific applications. However, the strict and complex interrelation among the chemical composition, size, polydispersity, shape and surface coating renders their correlation with the magnetic properties not trivial to predict. In this context, this work aims to discuss the magnetic properties and the heating abilities of Zn-substituted cobalt ferrite nanoparticles with different zinc contents (ZnxCo1-xFe2O4 with 0 < x < 0.6), specifically prepared with similar particle sizes (~7 nm) and size distributions having the crystallite size (~6 nm) and capping agent amount of 15%. All samples have high saturation magnetisation (Ms) values at 5 K (>100 emu g-1). The increase in the zinc content up to x = 0.46 in the structure has resulted in an increase of the saturation magnetisation (Ms) at 5 K. High Ms values have also been revealed at room temperature (~90 emu g-1) for both CoFe2O4 and Zn0.30Co0.70Fe2O4 samples and their heating ability has been tested. Despite a similar saturation magnetisation, the specific absorption rate value for the cobalt ferrite is three times higher than the Zn-substituted one. DC magnetometry results were not sufficient to justify these data, the experimental conditions of SAR and static measurements being quite different. The synergic combination of DC with AC magnetometry and 57Fe Mössbauer spectroscopy represents a powerful tool to get new insights into the design of suitable heat mediators for magnetic fluid hyperthermia.The possibility to finely control nanostructured cubic ferrites (MIIFe2O4) paves the way to design materials with the desired magnetic properties for specific applications. However, the strict and complex interrelation among the chemical composition, size, polydispersity, shape and surface coating renders their correlation with the magnetic properties not trivial to predict

  14. Brine Assemblages of Ultrasmall Microbial Cells within the Ice Cover of Lake Vida, Antarctica

    PubMed Central

    Kuhn, Emanuele; Ichimura, Andrew S.; Peng, Vivian; Fritsen, Christian H.; Trubl, Gareth; Doran, Peter T.

    2014-01-01

    The anoxic and freezing brine that permeates Lake Vida's perennial ice below 16 m contains an abundance of very small (≤0.2-μm) particles mixed with a less abundant population of microbial cells ranging from >0.2 to 1.5 μm in length. Fluorescent DNA staining, electron microscopy (EM) observations, elemental analysis, and extraction of high-molecular-weight genomic DNA indicated that a significant portion of these ultrasmall particles are cells. A continuous electron-dense layer surrounding a less electron-dense region was observed by EM, indicating the presence of a biological membrane surrounding a cytoplasm. The ultrasmall cells are 0.192 ± 0.065 μm, with morphology characteristic of coccoid and diplococcic bacterial cells, often surrounded by iron-rich capsular structures. EM observations also detected the presence of smaller unidentified nanoparticles of 0.020 to 0.140 μm among the brine cells. A 16S rRNA gene clone library from the brine 0.1- to 0.2-μm-size fraction revealed a relatively low-diversity assemblage of Bacteria sequences distinct from the previously reported >0.2-μm-cell-size Lake Vida brine assemblage. The brine 0.1- to 0.2-μm-size fraction was dominated by the Proteobacteria-affiliated genera Herbaspirillum, Pseudoalteromonas, and Marinobacter. Cultivation efforts of the 0.1- to 0.2-μm-size fraction led to the isolation of Actinobacteria-affiliated genera Microbacterium and Kocuria. Based on phylogenetic relatedness and microscopic observations, we hypothesize that the ultrasmall cells in Lake Vida brine are ultramicrocells that are likely in a reduced size state as a result of environmental stress or life cycle-related conditions. PMID:24727273

  15. Brine assemblages of ultrasmall microbial cells within the ice cover of Lake Vida, Antarctica.

    PubMed

    Kuhn, Emanuele; Ichimura, Andrew S; Peng, Vivian; Fritsen, Christian H; Trubl, Gareth; Doran, Peter T; Murray, Alison E

    2014-06-01

    The anoxic and freezing brine that permeates Lake Vida's perennial ice below 16 m contains an abundance of very small (≤0.2-μm) particles mixed with a less abundant population of microbial cells ranging from >0.2 to 1.5 μm in length. Fluorescent DNA staining, electron microscopy (EM) observations, elemental analysis, and extraction of high-molecular-weight genomic DNA indicated that a significant portion of these ultrasmall particles are cells. A continuous electron-dense layer surrounding a less electron-dense region was observed by EM, indicating the presence of a biological membrane surrounding a cytoplasm. The ultrasmall cells are 0.192 ± 0.065 μm, with morphology characteristic of coccoid and diplococcic bacterial cells, often surrounded by iron-rich capsular structures. EM observations also detected the presence of smaller unidentified nanoparticles of 0.020 to 0.140 μm among the brine cells. A 16S rRNA gene clone library from the brine 0.1- to 0.2-μm-size fraction revealed a relatively low-diversity assemblage of Bacteria sequences distinct from the previously reported >0.2-μm-cell-size Lake Vida brine assemblage. The brine 0.1- to 0.2-μm-size fraction was dominated by the Proteobacteria-affiliated genera Herbaspirillum, Pseudoalteromonas, and Marinobacter. Cultivation efforts of the 0.1- to 0.2-μm-size fraction led to the isolation of Actinobacteria-affiliated genera Microbacterium and Kocuria. Based on phylogenetic relatedness and microscopic observations, we hypothesize that the ultrasmall cells in Lake Vida brine are ultramicrocells that are likely in a reduced size state as a result of environmental stress or life cycle-related conditions.

  16. Ultrasensitive spectroscopy of ultrasmall quantum dots for energy conversion and lighting applications

    NASA Astrophysics Data System (ADS)

    Davis, Lloyd; Orfield, Noah; Rosenthal, Sandra

    2013-03-01

    Quantum dots typically have narrow spectra with a peak that tunes with their size but ultrasmall semiconductor nanocrystals of diameters less than a few nanometers have size-independent spectra and many other strikingly different properties. One especially interesting feature is that ultrasmall CdSe nanocrystals emit an almost pure white-light spectrum, which has great potential for solid-state lighting that yields excellent color rendering. To gain understanding of the photophysical properties and mechanisms for broadband emission, we have constructed a modular fluorescence microscope for ultrasensitive spectroscopy of individual nanoparticles. Using 400-nm wide-field excitation from a frequency-doubled Ti-Sapphire laser and a high-efficiency electron-multiplying CCD, we observe that single CdSe nanocrystals exhibit blinking and abrupt photobleaching, often after detection of only a few hundred photons. Moreover, spectrally dispersed imaging shows that each particle emits the entire broadband spectrum. We discuss mechanisms for homogeneous broadband emission and ongoing experiments in which the instrument is configured for scanning, confocal, two-channel, time-resolved single photon counting for studies of photon antibunching, emission lifetimes, and correlations between spectral regions.

  17. Ultrasmall Cu2-x S Nanodots for Highly Efficient Photoacoustic Imaging-Guided Photothermal Therapy.

    PubMed

    Mou, Juan; Li, Pei; Liu, Chengbo; Xu, Huixiong; Song, Liang; Wang, Jin; Zhang, Kun; Chen, Yu; Shi, Jianlin; Chen, Hangrong

    2015-05-20

    Monodisperse, ultrasmall (<5 nm) Cu(2-x)S nanodots (u-Cu(2-x)S NDs) with significantly strong near-infrared absorption and conversion are successfully demonstrated for effective deep-tissue photoacoustic imaging-guided photothermal therapy both in vitro and in vivo. Owing to ultrasmall nanoparticle size and high water dispersibility as well as long stability, such nanodots possess a prolonged circulation in blood and good passive accumulation within tumors through the enhanced permeability and retention effect. These u-Cu(2-x)S NDs have negligible side effects to both blood and normal tissues according to in vivo toxicity evaluations for up to 3 months, showing excellent hemo/histocompatibility. Furthermore, these u-Cu(2-x)S NDs can be thoroughly cleared through feces and urine within 5 days, showing high biosafety for further potential clinical translation. This novel photoacoustic imaging-guided photothermal therapy based on u-Cu(2-x)S NDs composed of a single component shows great prospects as a multifunctional nanoplatform with integration and multifunction for cancer diagnosis and therapy.

  18. Ultrasmall, well-dispersed, hollow siliceous spheres with enhanced endocytosis properties.

    PubMed

    Zhu, Jie; Tang, Jiawei; Zhao, Lingzhi; Zhou, Xufeng; Wang, Yunhua; Yu, Chengzhong

    2010-01-01

    The synthesis of ultrasmall, well-dispersed, hollow siliceous spheres (HSSs) by using a block copolymer as the template and tetraethoxysilane as a silica source under acidic conditions is reported. After removing the surfactant core of as-synthesized, spherical, silica-coated block-copolymer micelles, HSSs with a uniform particle size of 24.7 nm, a cavity diameter of 11.7 nm, and a wall thickness of 6.5 nm are obtained. It is shown that by surface functionalization of HSSs with methyl groups during synthesis, HSSs can be further dispersed in solvents such as water or ethanol to form a stable sol. Moreover, the hollow cavities are accessible for further loading of functional components. In addition, it is demonstrated that HSSs possess superior endocytosis properties for HeLa cells compared to those of conventional mesoporous silica nanoparticles. A feasible and designable strategy for synthesizing novel well-dispersed hollow structures with ultrasmall diameters instead of conventional ordered mesostructures is provided. It is expected that HSSs may find broad applications in bionanotechnology, such as drug carriers, cell imaging, and targeted therapy.

  19. Synthesis and characterization of a mixture of CoFe2O4 and MgFe2O4 from layered double hydroxides: Band gap energy and magnetic responses

    NASA Astrophysics Data System (ADS)

    Agú, Ulises A.; Oliva, Marcos I.; Marchetti, Sergio G.; Heredia, Angélica C.; Casuscelli, Sandra G.; Crivello, Mónica E.

    2014-11-01

    A mixture of nanocrystals of cobalt ferrite and magnesium ferrite was obtained from Layered Double Hydroxides (LDH) through a co-precitation method with a theoretical molar ratio M2+:Fe3+=3:1, where M2+represents Mg2+ and/or Co2+. The molar ratios between Co2+:Fe3+ were 0.0 (0Co), 0.2 (5Co), and 0.4 (10Co). In order to assess the effect on the properties of the LDH and their oxides, the molar percentages were 0, 5 and 10%. Two different synthesis methods were evaluated; (i) ageing at room temperature (rt), and (ii) hydrothermal ageing at 200 °C in autoclave (ht), both methods needed 15 h of ageing. Then, these LDH were calcined in air atmosphere at 550 °C for 10 h. The calcined materials were characterized by X-ray diffraction (XRD), thermogravymetric analysis (TGA), temperature-programmed reduction (TPR), infrared spectroscopy with Fourier transform (FTIR), Diffuse Reflectance UV-visible spectroscopy (UV-vis-DRS), Mössbauer spectroscopy and inductively coupled plasma optical emission spectroscopy (ICP-OES). The magnetic response was analyzed using a vibrating sample magnetometer (VSM). The band gap energy of the iron oxides was determined through the UV-vis-DRS analysis. Through these studies it was possible to identify the presence of a mixture of cobalt ferrite and magnesium ferrite. Samples did not show hematite and cobalt oxides, but the presence of MgO in the periclase phase was determined. This magnesium oxide promoted a good dispersion of the ferrites. Moreover, when a single ferrite phase of Co or Mg was formed, a diminution of the crystal size with consequent enlarged values of band gap energy was observed. Thus, materials synthesized by room temperature ageing promoted the superparamagnetic behaviour of samples, attributed to the content of the cobalt ferrite structure in nanocrystals. In regard to the estimated band gap energy, all samples exhibited low levels. These results indicate that these solids would be suitable for photocatalysts use in all visible light range, and that they could be easily removed from the reaction medium by a simple magnetic separation procedure.

  20. THE THICKNESS DEPENDENCE OF OXYGEN PERMEABILITY IN SOL-GEL DERIVED CGO-COFE2O4 THIN FILMS ON POROUS CERAMIC SUBSTRATES: A SPUTTERED BLOCKING LAYER FOR THICKNESS CONTROL

    SciTech Connect

    Brinkman, K

    2009-01-08

    Mixed conductive oxides are a topic of interest for applications in oxygen separation membranes as well as use in producing hydrogen fuel through the partial oxidation of methane. The oxygen flux through the membrane is governed both by the oxygen ionic conductivity as well as the material's electronic conductivity; composite membranes like Ce{sub 0.8}Gd{sub 0.2}O{sub 2-{delta}} (CGO)-CoFe{sub 2}O{sub 4} (CFO) use gadolinium doped ceria oxides as the ionic conducting material combined with cobalt iron spinel which serves as the electronic conductor. In this study we employ {approx} 50 nm sputtered CeO{sub 2} layers on the surface of porous CGO ceramic substrates which serve as solution 'blocking' layers during the thin film fabrication process facilitating the control of film thickness. Films with thickness of {approx} 2 and 4 microns were prepared by depositing 40 and 95 separate sol-gel layers respectively. Oxygen flux measurements indicated that the permeation increased with decreasing membrane thickness; thin film membrane with thickness on the micron level showed flux values an order of magnitude greater (0.03 {micro}mol/cm{sup 2} s) at 800 C as compared to 1mm thick bulk ceramic membranes (0.003 {micro}mol/cm{sup 2}).

  1. Magnetic ionic liquids produced by the dispersion of magnetic nanoparticles in 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI.NTf2).

    PubMed

    Medeiros, Anderson M M S; Parize, Alexandre L; Oliveira, Vanda M; Neto, Brenno A D; Bakuzis, Andris F; Sousa, Marcelo H; Rossi, Liane M; Rubim, Joel C

    2012-10-24

    ̀This paper reports on the advancement of magnetic ionic liquids (MILs) as stable dispersions of surface-modified γ-Fe(2)O(3), Fe(3)O(4), and CoFe(2)O(4) magnetic nanoparticles (MNPs) in a hydrophobic ionic liquid, 1-n-butyl 3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI.NTf(2)). The MNPs were obtained via coprecipitation and were characterized using powder X-ray diffraction, transmission electron microscopy, Raman spectroscopy and Fourier transform near-infrared (FT-NIR) spectroscopy, and magnetic measurements. The surface-modified MNPs (SM-MNPs) were obtained via the silanization of the MNPs with the aid of 1-butyl-3-[3-(trimethoxysilyl)propyl]imidazolium chloride (BMSPI.Cl). The SM-MNPs were characterized by Raman spectroscopy and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy and by magnetic measurements. The FTIR-ATR spectra of the SM-MNPs exhibited characteristic absorptions of the imidazolium and those of the Fe-O-Si-C moieties, confirming the presence of BMSPI.Cl on the MNP surface. Thermogravimetric analysis (TGA) showed that the SM-MNPs were modified by at least one BMSPI.Cl monolayer. The MILs were characterized using Raman spectroscopy, differential scanning calorimetry (DSC), and magnetic measurements. The Raman and DSC results indicated an interaction between the SM-MNPs and the IL. This interaction promotes the formation of a supramolecular structure close to the MNP surface that mimics the IL structure and is responsible for the stability of the MIL. Magnetic measurements of the MILs indicated no hysteresis. Superparamagnetic behavior and a saturation magnetization of ~22 emu/g could be inferred from the magnetic measurements of a sample containing 50% w/w γ-Fe(2)O(3) SM-MNP/BMI.NTf(2).

  2. Inflammatory imaging with ultrasmall superparamagnetic iron oxide.

    PubMed

    Matsushita, Taro; Kusakabe, Yoshinori; Fujii, Hitomi; Murase, Katsutoshi; Yamazaki, Youichi; Murase, Kenya

    2011-02-01

    The purpose of this study was to investigate the usefulness and feasibility of magnetic resonance imaging (MRI) with ultrasmall superparamagnetic iron oxide (USPIO) (USPIO-enhanced MRI) for imaging inflammatory tissues. First, we investigated the relationship between the apparent transverse relaxation rate (R2*) and the concentration of USPIO by phantom studies and measured the apparent transverse relaxivity (r2*) of USPIO. Second, we performed animal experiments using a total of 30 mice. The mice were divided into five groups [A (n=6), B (n=6), C (n=6), sham control (n=6), and control (n=6)]. The mice in Groups A, B, C and control were subcutaneously injected with 0.1 ml of turpentine oil on Day 0, while those in the sham control group were subcutaneously injected with 0.1 ml of saline. The mice in Groups A, B, C and sham control were intraperitoneally injected with 200 μmol Fe per kilogram body weight of USPIO (28 nm in diameter) immediately after the first MRI study on Days 3, 5, 7 and 7, respectively, and those in the control group were not injected with USPIO. The second and third MRI studies were performed at 24 and 48 h after USPIO administration, respectively. The maps of R2* were generated from the apparent transverse relaxation time (T2*)-weighted images with six different echo times. The phantom studies showed that there was a linear relationship between R2* and the concentration of USPIO (r=0.99) and the r2* value of USPIO was 105.7 mM(-1) s(-1). There was a significant increase of R2* in inflammatory tissues in Group C at 24 h after USPIO administration compared with the precontrast R2* value. Our results suggest that USPIO-enhanced MRI combined with R2* measurement is useful for detecting inflammatory tissues. PMID:20850245

  3. Ultrasmall Black Phosphorus Quantum Dots: Synthesis and Use as Photothermal Agents.

    PubMed

    Sun, Zhengbo; Xie, Hanhan; Tang, Siying; Yu, Xue-Feng; Guo, Zhinan; Shao, Jundong; Zhang, Han; Huang, Hao; Wang, Huaiyu; Chu, Paul K

    2015-09-21

    Black phosphorus quantum dots (BPQDs) were synthesized using a liquid exfoliation method that combined probe sonication and bath sonication. With a lateral size of approximately 2.6 nm and a thickness of about 1.5 nm, the ultrasmall BPQDs exhibited an excellent NIR photothermal performance with a large extinction coefficient of 14.8 L g(-1) cm(-1) at 808 nm, a photothermal conversion efficiency of 28.4%, as well as good photostability. After PEG conjugation, the BPQDs showed enhanced stability in physiological medium, and there was no observable toxicity to different types of cells. NIR photoexcitation of the BPQDs in the presence of C6 and MCF7 cancer cells led to significant cell death, suggesting that the nanoparticles have large potential as photothermal agents.

  4. Cobalt ferrite nanoparticles decorated on exfoliated graphene oxide, application for amperometric determination of NADH and H2O2.

    PubMed

    Ensafi, Ali A; Alinajafi, Hossein A; Jafari-Asl, M; Rezaei, B; Ghazaei, F

    2016-03-01

    Here, cobalt ferrite nanohybrid decorated on exfoliated graphene oxide (CoFe2O4/EGO) was synthesized. The nanohybrid was characterized by different methods such as X-ray diffraction spectroscopy, scanning electron microscopy, energy dispersive X-ray diffraction microanalysis, transmission electron microscopy, FT-IR, Raman spectroscopy and electrochemical methods. The CoFe2O4/EGO nanohybrid was used to modify glassy carbon electrode (GCE). The voltammetric investigations showed that CoFe2O4/EGO nanohybrid has synergetic effect towards the electro-reduction of H2O2 and electro-oxidation of nicotinamide adenine dinucleotide (NADH). Rotating disk chronoamperometry was used for their quantitative analysis. The calibration curves were observed in the range of 0.50 to 100.0 μmol L(-1) NADH and 0.9 to 900.0 μmol L(-1) H2O2 with detections limit of 0.38 and 0.54 μmol L(-1), respectively. The repeatability, reproducibility and selectivity of the electrochemical sensor for analysis of the analytes were studied. The new electrochemical sensor was successfully applied for the determination of NADH and H2O2 in real samples with satisfactory results.

  5. Dynamic fluctuations in ultrasmall nanocrystals induce white light emission

    SciTech Connect

    Pennycook, Timothy J; Mcbride, J. R.; Rosenthal, Sandra; Pennycook, Stephen J; Pantelides, Sokrates T.

    2012-01-01

    Nanocrystals typically emit monochromatically at their size-dependent energy gaps. Recently, it was found that by pushing the size of a nanocrystal to its lower limits, absorption occurs at increasingly larger energies, but the expected blue to ultraviolet emission does not occur. Instead, individual ultrasmall CdSe nanocrystals emit white light1-5. Here we show that following excitation, partial thermalization sets the ultrasmall nanocrystals into a fluxional6 state, with a continuously varying energy gap which results in white light emission. Even the larger, monochromatic nanocrystals have a fluxional surface but a stable crystal core. A degree of fluxionality persists even at room temperature and represents a radical change to the accepted view of nanocrystals, with wide-ranging ramifications for other applications. The results were obtained using a combination of state-of-the-art experiment and theory: dynamic imaging by aberration-corrected scanning transmission electron microscopy and finite-temperature quantum molecular dynamics simulations. The results show that small is different, but ultrasmall is different yet again.

  6. Mesoscopic superconductivity in ultrasmall metallic grains

    SciTech Connect

    Alhassid, Y.; Nesterov, K. N.

    2014-10-15

    A nano-scale metallic grain (nanoparticle) with irregular boundaries in which the single-particle dynamics are chaotic is a zero-dimensional system described by the so-called universal Hamiltonian in the limit of a large number of electrons. The interaction part of this Hamiltonian includes a superconducting pairing term and a ferromagnetic exchange term. Spin-orbit scattering breaks spin symmetry and suppresses the exchange interaction term. Of particular interest is the fluctuation-dominated regime, typical of the smallest grains in the experiments, in which the bulk pairing gap is comparable to or smaller than the single-particle mean-level spacing, and the Bardeen-Cooper-Schrieffer (BCS) mean-field theory of superconductivity is no longer valid. Here we study the crossover between the BCS and fluctuation-dominated regimes in two limits. In the absence of spin-orbit scattering, the pairing and exchange interaction terms compete with each other. We describe the signatures of this competition in thermodynamic observables, the heat capacity and spin susceptibility. In the presence of strong spin-orbit scattering, the exchange interaction term can be ignored. We discuss how the magnetic-field response of discrete energy levels in such a nanoparticle is affected by pairing correlations. We identify signatures of pairing correlations in this response, which are detectable even in the fluctuation-dominated regime.

  7. Spinning Dust Emission from Ultra-small Silicates: Emissivity and Polarization Spectrum

    NASA Astrophysics Data System (ADS)

    Hoang, Thiem; Vinh, Nguyen-Anh; Quynh Lan, Nguyen

    2016-06-01

    Anomalous microwave emission (AME) is an important Galactic foreground of cosmic microwave background radiation. It is believed that AME arises from rotational emission by spinning polycyclic aromatic hydrocarbons in the interstellar medium (ISM). In this paper, we suppose that a new population of ultra-small silicate grains perhaps exists in the ISM, and quantify the rotational emissivity from these tiny particles and its polarization spectrum. We find that spinning silicate nanoparticles can produce strong rotational emission when the tiny grains follow a log-normal size distribution. The polarization fraction of spinning dust emission from tiny silicates increases with decreasing dipole moment per atom (β) and can reach P˜ 20 % for β ˜ 0.1 {{D}} at a grain temperature of 60 K. We identify a parameter space (β ,{Y}{{Si}}), with {Y}{{Si}} being the fraction of Si abundance in nanoparticles, in which its rotational emission can adequately reproduce both the observed AME and the polarization of the AME, without violating the observational constraints of ultraviolet extinction and polarization of starlight. Our results reveal that rotational emission from spinning silicate may be an important source of AME.

  8. Ultrasmall mixed ferrite colloids as multidimensional magnetic resonance imaging, cell labeling, and cell sorting agents.

    PubMed

    Groman, Ernest V; Bouchard, Jacqueline C; Reinhardt, Christopher P; Vaccaro, Dennis E

    2007-01-01

    One area that has been overlooked in the evolution of magnetic nanoparticle technology is the possibility of introducing informational atoms into the iron oxide core of the coated colloid. Introduction of suitable atoms into the iron oxide core offers an opportunity to produce a quantifiable probe, thereby adding one or more dimensions to the magnetic colloid's informational status. Lanthanide-doped iron oxide nanoparticles have been synthesized to introduce informational atoms through the formation of colloidal mixed ferrites. These colloids are designated ultrasmall mixed ferrite iron oxides (USMIOs). USMIOs containing 5 mol % europium exhibit superparamagnetic behavior with an induced magnetization of 56 emu/g Fe at 1.5 T, a powder X-ray diffraction pattern congruent with magnetite, and R1 and R2 relaxivity values of 15.4 (mM s) (-1) and 33.9 (mM s) (-1), respectively, in aqueous solution at 37 degrees C and 0.47 T. USMIO can be detected by five physical methods, combining the magnetic resonance imaging (MRI) qualities of iron with the sensitive and quantitative detection of lanthanide metals by neutron activation analysis (NA), time-resolved fluorescence (TRF), X-ray fluorescence, along with detection by electron microscopy (EM). In addition to quantitative detection using neutron activation analysis, the presence of lanthanides in the iron oxide matrix confers attractive optical properties for long-term multilabeling studies with europium and terbium. These USMIOs offer high photostability, a narrow emission band, and a broad absorption band combining the high sensitivity of time-resolved fluorescence with the high spatial resolution of MRI. USMIO nanoparticles are prepared through modifications of traditional magnetite-based iron oxide colloid synthetic methods. A 5 mol % substitution of ferric iron with trivalent europium yielded a colloid with nearly identical magnetic, physical, and chemical characteristics to its magnetite colloid parent.

  9. Bright White Light Emission from Ultrasmall Cadmium Selenide Nanocrystals

    SciTech Connect

    Rosson, Teresa; Claiborne, Sarah; McBride, James; Stratton, Benjamin S; Rosenthal, Sandra

    2012-01-01

    A simple treatment method using formic acid has been found to increase the fluorescence quantum yield of ultrasmall white light-emitting CdSe nanocrystals from 8% to 45%. Brighter white-light emission occurs with other carboxylic acids as well, and the magnitude of the quantum yield enhancement is shown to be dependent on the alkyl chain length. Additionally, the nanocrystal luminescence remains enhanced relative to the untreated nanocrystals over several days. This brightened emission opens the possibility for even further quantum yield improvement and potential for use of these white-light nanocrystals in solid-state lighting applications.

  10. Synthesis, kinetics and photocatalytic study of "ultra-small" Ag-NPs obtained by a green chemistry method using an extract of Rosa 'Andeli' double delight petals.

    PubMed

    Suárez-Cerda, Javier; Alonso-Nuñez, Gabriel; Espinoza-Gómez, Heriberto; Flores-López, Lucía Z

    2015-11-15

    This paper reports the effect of different concentrations of Rosa 'Andeli' double delight petals aqueous extract (PERA) in the synthesis of silver nanoparticles (Ag-NPs), using an easy green chemistry method. Its kinetics study and photocatalytic activity were also evaluated. The Ag-NPs were obtained using an aqueous silver nitrate solution (AgNO3) with 9.66% w/v, 7.25% w/v, and 4.20% w/v PERA as both reducing-stabilizing agent. The formation of the Ag-NPs was demonstrated by analysis of UV-vis spectroscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). TEM analysis shows spherical nanoparticles in shape and size between ∼0.5 and 1.4nm. A comparative study was done to determine which concentration was the best reducing-stabilizing agent, and we found out that "ultra-small" nanoparticles (0.5-1.1nm) were obtained with 9.66% w/v of PERA. The size of the Ag-NPs depends on the concentration of PERA and Ag(I). The reaction of formation of "ultra-small" Ag-NPs, proved to be first order for metallic precursor (silver) and second order for reducing-stabilizing agent (PERA). The Ag-NPs showed photocatalytic activity, in degradation of commercial dye with an efficiency of 95%. PMID:26218196

  11. Synthesis, kinetics and photocatalytic study of "ultra-small" Ag-NPs obtained by a green chemistry method using an extract of Rosa 'Andeli' double delight petals.

    PubMed

    Suárez-Cerda, Javier; Alonso-Nuñez, Gabriel; Espinoza-Gómez, Heriberto; Flores-López, Lucía Z

    2015-11-15

    This paper reports the effect of different concentrations of Rosa 'Andeli' double delight petals aqueous extract (PERA) in the synthesis of silver nanoparticles (Ag-NPs), using an easy green chemistry method. Its kinetics study and photocatalytic activity were also evaluated. The Ag-NPs were obtained using an aqueous silver nitrate solution (AgNO3) with 9.66% w/v, 7.25% w/v, and 4.20% w/v PERA as both reducing-stabilizing agent. The formation of the Ag-NPs was demonstrated by analysis of UV-vis spectroscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). TEM analysis shows spherical nanoparticles in shape and size between ∼0.5 and 1.4nm. A comparative study was done to determine which concentration was the best reducing-stabilizing agent, and we found out that "ultra-small" nanoparticles (0.5-1.1nm) were obtained with 9.66% w/v of PERA. The size of the Ag-NPs depends on the concentration of PERA and Ag(I). The reaction of formation of "ultra-small" Ag-NPs, proved to be first order for metallic precursor (silver) and second order for reducing-stabilizing agent (PERA). The Ag-NPs showed photocatalytic activity, in degradation of commercial dye with an efficiency of 95%.

  12. Engineering ultrasmall water-soluble gold and silver nanoclusters for biomedical applications.

    PubMed

    Luo, Zhentao; Zheng, Kaiyuan; Xie, Jianping

    2014-05-25

    Gold and silver nanoclusters or Au/Ag NCs with core sizes smaller than 2 nm have been an attractive frontier of nanoparticle research because of their unique physicochemical properties such as well-defined molecular structure, discrete electronic transitions, quantized charging, and strong luminescence. As a result of these unique properties, ultrasmall size, and good biocompatibility, Au/Ag NCs have great potential for a variety of biomedical applications, such as bioimaging, biosensing, antimicrobial agents, and cancer therapy. In this feature article, we will first discuss some critical biological considerations, such as biocompatibility and renal clearance, of Au/Ag NCs that are applied for biomedical applications, leading to some design criteria for functional Au/Ag NCs in the biological settings. According to these biological considerations, we will then survey some efficient synthetic strategies for the preparation of protein- and peptide-protected Au/Ag NCs with an emphasis on our recent contributions in this fast-growing field. In the last part, we will highlight some potential biomedical applications of these protein- and peptide-protected Au/Ag NCs. It is believed that with continued efforts to understand the interactions of biomolecule-protected Au/Ag NCs with the biological systems, scientists can largely realize the great potential of Au/Ag NCs for biomedical applications, which could finally pave their way towards clinical use.

  13. Physicochemical characterization of ultrasmall superparamagnetic iron oxide particles (USPIO) for biomedical application as MRI contrast agents

    PubMed Central

    Di Marco, Mariagrazia; Sadun, Claudia; Port, Marc; Guilbert, Irene; Couvreur, Patrick; Dubernet, Catherine

    2007-01-01

    Ultrasmall superparamagnetic iron oxide (USPIO) particles are maghemite or magnetite nanoparticles currently used as contrast agent in magnetic resonance imaging. The coatings surrounding the USPIO inorganic core play a major role in both the in vitro stability and, over all, USPIO’s in vivo fate. Different physicochemical properties such as final size, surface charge and coating density are key factors in this respect. Up to now no precise structure – activity relationship has been described to predict entirely the USPIOs stability, as well as their pharmacokinetics and their safety. This review is focused on both the classical and the latest available techniques allowing a better insight in the magnetic core structure and the organic surface of these particles. Concurrently, this work clearly shows the difficulty to obtain a complete physicochemical characterization of USPIOs particles owing to their small dimensions, reaching the analytical resolution limits of many commercial instruments. An extended characterization is therefore necessary to improve the understanding of the properties of USPIOs when dispersed in an aqueous environment and to set the specifications and limits for their conception. PMID:18203428

  14. Ultra-small, highly stable, and membrane-impermeable fluorescent nanosensors for oxygen

    NASA Astrophysics Data System (ADS)

    Wang, Xu-dong; Stolwijk, Judith A.; Sperber, Michaela; Meier, Robert J.; Wegener, Joachim; Wolfbeis, Otto S.

    2013-09-01

    We report on the preparation of ultra-small fluorescent nanosensors for oxygen via a one-pot approach. The nanoparticles have a hydrophobic core capable of firmly hosting hydrophobic luminescent oxygen probes. Their surface is composed of a dense and long-chain poly(ethylene glycol) shell, which renders them cell-membrane impermeable but yet highly sensitive to oxygen, and also highly stable in aqueous solutions and cell culture media. These features make them potentially suitable for sensing oxygen in extracellular fluids such as blood, interstitial and brain fluid, in (micro) bioreactors and micro- or nanoscale fluidic devices. Four kinds of nanosensors are presented, whose excitation spectra cover a wide spectral range (395-630 nm), thus matching many common laser lines, and with emission maxima ranging from 565 to 800 nm, thereby minimizing interference from background luminescence of biomatter. The unquenched lifetimes are on the order of 5.8-234 μs, which—in turn—enables lifetime imaging and additional background separation via time-gated methods.

  15. Ultrasmall hollow gold-silver nanoshells with extinctions strongly red-shifted to the near-infrared.

    PubMed

    Vongsavat, Varadee; Vittur, Brandon M; Bryan, William W; Kim, Jun-Hyun; Lee, T Randall

    2011-09-01

    Hollow gold-silver nanoshells having systematically varying sizes between 40 and 100 nm were prepared. These particles consist of a hollow spherical silver shell surrounded by a thin gold layer. By varying the volume of the gold stock solution added to suspensions of small silver-core templates, we tailored the hollow gold-silver nanoshells to possess strong tunable optical extinctions that range from the visible to the near-IR spectral regions, with extinctions routinely centered at ∼950 nm. The size and morphology of these core/shell nanoparticles were characterized by dynamic light scattering (DLS), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Separately, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used for measuring their elemental composition; UV-vis spectroscopy was used to evaluate their optical properties. Given their relatively small size compared to other nanoparticles that absorb strongly at near IR wavelengths, these easy-to-synthesize particles should find use in applications that require ultrasmall nanoparticles with extinctions comfortably beyond visible wavelengths (e.g., medicinal therapies, diagnostic imaging, nanofluidics, and display technologies). PMID:21761855

  16. Hierarchical nanostructures are crucial to mitigate ultrasmall thermal point loads.

    PubMed

    Xu, Zhiping; Buehler, Markus J

    2009-05-01

    Here we show that hierarchical structures based on one-dimensional filaments such as carbon nanotubes lead to superior thermal management networks, capable of effectively mitigating high-density ultrasmall nanoscale heat sources through volumetric heat sinks at micrometer and larger scales. The figure of merit of heat transfer is quantified through the effective thermal conductance as well as the steady-state temperature distribution in the network. In addition to providing an overall increased thermal conductance, we find that hierarchical structures drastically change the temperature distribution in the immediate vicinity of a heat source, significantly lowering the temperature at shorter distances. Our work brings about a synergistic viewpoint that combines advances in materials synthesis and insight gained from hierarchical biological structures, utilized to create novel functional materials with exceptional thermal properties. PMID:19323550

  17. Cytotoxicity, tumor targeting and PET imaging of sub-5 nm KGdF4 multifunctional rare earth nanoparticles.

    PubMed

    Cao, Xinmin; Cao, Fengwen; Xiong, Liqin; Yang, Yang; Cao, Tianye; Cai, Xi; Hai, Wangxi; Li, Biao; Guo, Yixiao; Zhang, Yimin; Li, Fuyou

    2015-08-28

    Ultrasmall sub-5 nm KGdF4 rare earth nanoparticles were synthesized as multifunctional probes for fluorescent, magnetic, and radionuclide imaging. The cytotoxicity of these nanoparticles in human glioblastoma U87MG and human non-small cell lung carcinoma H1299 cells was evaluated, and their application for in vitro and in vivo tumor targeted imaging has also been demonstrated.

  18. Magnetization and stability study of a cobalt-ferrite-based ferrofluid

    NASA Astrophysics Data System (ADS)

    Kamali, Saeed; Pouryazdan, Mohsen; Ghafari, Mohammad; Itou, Masayoshi; Rahman, Masoud; Stroeve, Pieter; Hahn, Horst; Sakurai, Yoshiharu

    2016-04-01

    In this study the structural and magnetization properties of a CoFe2O4-based ferrofluid was investigated using x-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), Mössbauer spectroscopy, and magnetic Compton scattering (MCS) measurements. The XRD diagram indicates that the nanoparticles in the ferrofluid are inverse spinel and TEM graph shows that the ferrofluid consists of spherical nanoparticles with an average diameter of 18± 1 nm, in good agreement with the size, 19.4 nm, extracted from line broadening of the XRD peaks. According to EDS measurements the composition of the nanoparticles is CoFe2O4. Mössbauer spectroscopy shows that the cation distributions are (Co0.38Fe0.62)[Co0.62Fe1.38]O4. The MCS measurement, performed at 10 K, indicates that the magnetization of the nanoparticles is similar to magnetization of maghemite and magnetite. While the magnetization of the inverse spinels are in [111] direction, interestingly, the magnetization deduced from MCS is in [100] direction. The CoFe2O4-based ferrofluid is found to be stable at ambient conditions, which is important for applications.

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

    NASA Astrophysics Data System (ADS)

    Pulišová, P.; Kováč, J.; Voigt, A.; Raschman, P.

    2013-09-01

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

  20. Ultrasmall superparamagnetic iron oxide (USPIO)-based liposomes as magnetic resonance imaging probes

    PubMed Central

    Frascione, Daniela; Diwoky, Clemens; Almer, Gunter; Opriessnig, Peter; Vonach, Caroline; Gradauer, Kerstin; Leitinger, Gerd; Mangge, Harald; Stollberger, Rudolf; Prassl, Ruth

    2012-01-01

    Background Magnetic liposomes (MLs) are phospholipid vesicles that encapsulate magnetic and/or paramagnetic nanoparticles. They are applied as contrast agents for magnetic resonance imaging (MRI). MLs have an advantage over free magnetic nanocores, in that various functional groups can be attached to the surface of liposomes for ligand-specific targeting. We have synthesized PEG-coated sterically-stabilized magnetic liposomes (sMLs) containing ultrasmall superparamagnetic iron oxides (USPIOs) with the aim of generating stable liposomal carriers equipped with a high payload of USPIOs for enhanced MRI contrast. Methods Regarding iron oxide nanoparticles, we have applied two different commercially available surface-coated USPIOs; sMLs synthesized and loaded with USPIOs were compared in terms of magnetization and colloidal stability. The average diameter size, morphology, phospholipid membrane fluidity, and the iron content of the sMLs were determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), fluorescence polarization, and absorption spectroscopy, respectively. A colorimetric assay using potassium thiocyanate (KSCN) was performed to evaluate the encapsulation efficiency (EE%) to express the amount of iron enclosed into a liposome. Subsequently, MRI measurements were carried out in vitro in agarose gel phantoms to evaluate the signal enhancement on T1- and T2-weighted sequences of sMLs. To monitor the biodistribution and the clearance of the particles over time in vivo, sMLs were injected in wild type mice. Results DLS revealed a mean particle diameter of sMLs in the range between 100 and 200 nm, as confirmed by TEM. An effective iron oxide loading was achieved just for one type of USPIO, with an EE% between 74% and 92%, depending on the initial Fe concentration (being higher for lower amounts of Fe). MRI measurements demonstrated the applicability of these nanostructures as MRI probes. Conclusion Our results show that the development of

  1. Hydrogen gas sensing with networks of ultra-small palladium nanowires formed on filtration membranes.

    SciTech Connect

    Zeng, X. Q.; Latimer, M. L.; Xiao, Z. L.; Panuganti, S.; Welp, U.; Kwok, W. K.; Xu, T.

    2010-11-29

    Hydrogen sensors based on single Pd nanowires show promising results in speed, sensitivity, and ultralow power consumption. The utilization of single Pd nanowires, however, face challenges in nanofabrication, manipulation, and achieving ultrasmall transverse dimensions. We report on hydrogen sensors that take advantage of single palladium nanowires in high speed and sensitivity and that can be fabricated conveniently. The sensors are based on networks of ultrasmall (<10 nm) palladium nanowires deposited onto commercially available filtration membranes. We investigated the sensitivities and response times of these sensors as a function of the thickness of the nanowires and also compared them with a continuous reference film. The superior performance of the ultrasmall Pd nanowire network based sensors demonstrates the novelty of our fabrication approach, which can be directly applied to palladium alloy and other hydrogen sensing materials.

  2. Hydrogen gas sensing with networks of ultrasmall palladium nanowires formed on filtration membranes.

    PubMed

    Zeng, X Q; Latimer, M L; Xiao, Z L; Panuganti, S; Welp, U; Kwok, W K; Xu, T

    2011-01-12

    Hydrogen sensors based on single Pd nanowires show promising results in speed, sensitivity, and ultralow power consumption. The utilization of single Pd nanowires, however, face challenges in nanofabrication, manipulation, and achieving ultrasmall transverse dimensions. We report on hydrogen sensors that take advantage of single palladium nanowires in high speed and sensitivity and that can be fabricated conveniently. The sensors are based on networks of ultrasmall (<10 nm) palladium nanowires deposited onto commercially available filtration membranes. We investigated the sensitivities and response times of these sensors as a function of the thickness of the nanowires and also compared them with a continuous reference film. The superior performance of the ultrasmall Pd nanowire network based sensors demonstrates the novelty of our fabrication approach, which can be directly applied to palladium alloy and other hydrogen sensing materials.

  3. Measuring and controlling the transport of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Stephens, Jason R.

    Despite the large body of literature describing the synthesis of magnetic nanoparticles, few analytical tools are commonly used for their purification and analysis. Due to their unique physical and chemical properties, magnetic nanoparticles are appealing candidates for biomedical applications and analytical separations. Yet in the absence of methods for assessing and assuring their purity, the ultimate use of magnetic particles and heterostructures is likely to be limited. For magnetic nanoparticles, it is the use of an applied magnetic flux or field gradient that enables separations. Flow based techniques are combined with applied magnetic fields to give methods such as magnetic field flow fractionation and high gradient magnetic separation. Additional techniques have been explored for manipulating particles in microfluidic channels and in mesoporous membranes. This thesis further describes development of these and new analytical tools for separation and analysis of colloidal particles is critically important to enable the practical use of these, particularly for medicinal purposes. Measurement of transport of nanometer scale particles through porous media is important to begin to understand the potential environmental impacts of nanomaterials. Using a diffusion cell with two compartments separated by either a porous alumina or polycarbonate membrane as a model system, diffusive flux through mesoporous materials is examined. Experiments are performed as a function of particle size, pore diameter, and solvent, and the particle fluxes are monitored by the change in absorbance of the solution in the receiving cell. Using the measured extinction coefficient and change in absorbance of the solution as a function of time, the fluxes of 3, 8, and 14 nm diameter CoFe2O4 particles are determined as they are translocated across pores with diameters 30, 50, 100, and 200 nm in hexane and aqueous solutions. In general, flux decreases with increasing particle size and

  4. Oscillatory-like relaxation behavior of light transmitted through ferrofluids.

    PubMed

    Li, Jian; Qiu, Xiaoyan; Lin, Yueqiang; Liu, Xiaodong; Fu, Jun; Miao, Hua; Zhang, Qingmei; Zhang, Tingzhen

    2011-10-20

    An oscillatory-like relaxation process in which there are two valleys in the T-t curve is observed when light is transmitted through binary ferrofluids composed of both ferrimagnetic CoFe(2)O(4) nanoparticles and paramagnetic p-MgFe(2)O(4) nanoparticles in the presence of a high magnetic field and through pure (single) CoFe(2)O(4) ferrofluids in a low magnetic field. This relaxation behavior is explained using a model of a bidispersed system based on both chained and unchained particles. In such a bidispersed system, the variation of the transmitted light results mainly from the motion of the chains, with the polarized unchained particles' gas producing the modulation effect. The oscillatory-like relaxation phenomenon depends on the features of both the chained and unchained particle systems. If either the particle volume fraction of chained particles or of unchained particles is very low, or the degree of polarization of the unchained particles gas is very weak, a simple nonlinear relaxation process, giving only a valley in the T-t curve, will appear for the transmitted light. For pure CoFe(2)O(4) ferrofluids, the number of chained and unchained particles does not remain constant under different values of the magnetic field. According to the analysis of the relaxation behavior of transmitted light, it is known that binary ferrofluids based on strong magnetic CoFe(2)O(4) particles and weak magnetic p-MgFe(2)O(4) particles can be much closer to the theoretical bidispersed system than single ferrofluids containing only strong magnetic particles. PMID:22015404

  5. nanoparticles

    NASA Astrophysics Data System (ADS)

    Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J. Enrique

    2014-10-01

    Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.

  6. In Situ Confinement of Ultrasmall Pd Clusters within Nanosized Silicalite-1 Zeolite for Highly Efficient Catalysis of Hydrogen Generation.

    PubMed

    Wang, Ning; Sun, Qiming; Bai, Risheng; Li, Xu; Guo, Guanqi; Yu, Jihong

    2016-06-22

    Well-dispersed and ultrasmall Pd clusters in nanosized silicalite-1 (MFI) zeolite have been prepared under direct hydrothermal conditions using [Pd(NH2CH2CH2NH2)2]Cl2 as precursor. High-resolution scanning transmission electron microscopy studies indicate that the Pd clusters are encapsulated within the intersectional channels of MFI, and the Pd clusters in adjacent channels visually aggregate, forming nanoparticles (NPs) of ∼1.8 nm. The resultant catalysts show an excellent activity and highly efficient H2 generation toward the complete decomposition of formic acid (FA) under mild conditions. Notably, thanks to the further reduced Pd NP size (∼1.5 nm) and the additionally introduced basic sites, the Pd/S-1-in-K catalyst affords turnover frequency values up to 856 h(-1) at 25 °C and 3027 h(-1) at 50 °C. The easy in situ confinement synthesis of metal clusters in zeolites endows the catalysts with superior catalytic activities, excellent recyclability, and high thermal stability, thus opening new perspectives for the practical application of FA as a viable and effective H2 storage material for use in fuel cells. PMID:27248462

  7. Ultrasmall Biocompatible WO3- x Nanodots for Multi-Modality Imaging and Combined Therapy of Cancers.

    PubMed

    Wen, Ling; Chen, Ling; Zheng, Shimin; Zeng, Jianfeng; Duan, Guangxin; Wang, Yong; Wang, Guanglin; Chai, Zhifang; Li, Zhen; Gao, Mingyuan

    2016-07-01

    Ultrasmall biocompatible WO3 - x nanodots with an outstanding X-ray radiation sensitization effect are prepared, and demonstrated to be applicable for multi-modality tumor imaging through computed tomography and photoacoustic imaging (PAI), and effective cancer treatment combining both photothermal therapy and radiation therapy.

  8. Fabrication and multifunctional properties of ultrasmall water-soluble tungsten oxide quantum dots.

    PubMed

    Peng, Huaping; Liu, Pan; Lin, Danwei; Deng, Yani; Lei, Yun; Chen, Wei; Chen, Yuanzhong; Lin, Xinhua; Xia, Xinghua; Liu, Ailin

    2016-07-21

    A facile and green method has been demonstrated to synthesize ultrasmall tungsten oxide quantum dots (WOx QDs). The water-soluble WOx QDs present high luminescence stability, strong peroxidase-like activity, and excellent electrochemiluminescence properties. This work provides an eco-friendly strategy to prepare multifunctional WOx QDs, and opens the door for bioapplications of the WOx QDs. PMID:27381501

  9. Pluriformity of inflammation in multiple sclerosis shown by ultra-small iron oxide particle enhancement.

    PubMed

    Vellinga, Machteld M; Oude Engberink, Raoul D; Seewann, Alexandra; Pouwels, Petra J W; Wattjes, Mike P; van der Pol, Susanne M A; Pering, Christiane; Polman, Chris H; de Vries, Helga E; Geurts, Jeroen J G; Barkhof, Frederik

    2008-03-01

    Gadolinium-DTPA (Gd-DTPA) is routinely used as a marker for inflammation in MRI to visualize breakdown of the blood-brain barrier (BBB) in multiple sclerosis. Recent data suggest that ultra-small superparamagnetic particles of iron oxide (USPIO) can be used to visualize cellular infiltration, another aspect of inflammation. This project aimed to compare the novel USPIO particle SHU555C to the longitudinal pattern of Gd-DTPA enhancement in multiple sclerosis. Nineteen relapsing-remitting patients were screened monthly using Gd-enhanced MRI. In case of new enhancing lesions, USPIO were injected and 24 h later, MRI was performed and blood was collected to confirm USPIO loading of circulating monocytes. Lesion development was monitored by 3 monthly Gd-DTPA-enhanced scans and a final scan 7-11 months after injection. USPIO-enhancement was observed as hyperintensity on T1-weighted images, whereas no signal changes were observed on T2-weighted-gradient-echo images. In 14 patients with disease activity, 188 USPIO-positive lesions were seen, 144 of which were Gd-negative. By contrast, there were a total of 59 Gd-positive lesions, 15 of which were USPIO negative. Three patterns of USPIO-enhancement were seen: (i) focal enhancement; (ii) ring-like enhancement and (iii) return to isointensity of a previously hypointense lesion. The latter pattern was most frequently observed for lesions that turned out to be transiently hypointense on follow-up scans, and ring-enhancing lesions were less likely to evolve into black holes at follow-up than lesions without ring-like USPIO-enhancement; we speculate this to be associated with repair. In 4% of the USPIO-positive/Gd negative lesions, USPIO-enhancement preceded Gd-enhancement by 1 month. USPIO-enhancement remained visible for up to 3 months in 1.5% of all USPIO-positive lesions. In 29% of the lesions enhancing with both contrast agents, USPIO-enhancement persisted whereas Gd-enhancement had already resolved. In conclusion, the new

  10. ²⁰¹Tl⁺-labelled Prussian blue nanoparticles as contrast agents for SPECT scintigraphy.

    PubMed

    Perrier, M; Busson, M; Massasso, G; Long, J; Boudousq, V; Pouget, J-P; Peyrottes, S; Perigaud, Ch; Porredon-Guarch, C; de Lapuente, J; Borras, M; Larionova, J; Guari, Y

    2014-11-21

    Prussian blue (PB) and its analogues on the nanometric scale are exciting nano-objects that combine the advantages of molecular-based materials and nanochemistry. Herein, we demonstrate that ultra-small PB nanoparticles of 2-3 nm can be easily labelled with radioactive (201)Tl(+) to obtain new nanoprobes as radiotracers for 201-thallium-based imaging.

  11. Tunable Ultrasmall Visible-to-Extended Near-Infrared Emitting Silver Sulfide Quantum Dots for Integrin-Targeted Cancer Imaging

    PubMed Central

    2016-01-01

    The large size of many near-infrared (NIR) fluorescent nanoparticles prevents rapid extravasation from blood vessels and subsequent diffusion to tumors. This confines in vivo uptake to the peritumoral space and results in high liver retention. In this study, we developed a viscosity modulated approach to synthesize ultrasmall silver sulfide quantum dots (QDs) with distinct tunable light emission from 500 to 1200 nm and a QD core diameter between 1.5 and 9 nm. Conjugation of a tumor-avid cyclic pentapeptide (Arg-Gly-Asp-DPhe-Lys) resulted in monodisperse, water-soluble QDs (hydrodynamic diameter < 10 nm) without loss of the peptide’s high binding affinity to tumor-associated integrins (KI = 1.8 nM/peptide). Fluorescence and electron microscopy showed that selective integrin-mediated internalization was observed only in cancer cells treated with the peptide-labeled QDs, demonstrating that the unlabeled hydrophilic nanoparticles exhibit characteristics of negatively charged fluorescent dye molecules, which typically do not internalize in cells. The biodistribution profiles of intravenously administered QDs in different mouse models of cancer reveal an exceptionally high tumor-to-liver uptake ratio, suggesting that the small sized QDs evaded conventional opsonization and subsequent high uptake in the liver and spleen. The seamless tunability of the QDs over a wide spectral range with only a small increase in size, as well as the ease of labeling the bright and noncytotoxic QDs with biomolecules, provides a platform for multiplexing information, tracking the trafficking of single molecules in cells, and selectively targeting disease biomarkers in living organisms without premature QD opsonization in circulating blood. PMID:25560768

  12. General Approach for MOF-Derived Porous Spinel AFe2O4 Hollow Structures and Their Superior Lithium Storage Properties.

    PubMed

    Yu, Hong; Fan, Haosen; Yadian, Boluo; Tan, Huiteng; Liu, Weiling; Hng, Huey Hoon; Huang, Yizhong; Yan, Qingyu

    2015-12-01

    A general and simple approach for large-scale synthesis of porous hollow spinel AFe2O4 nanoarchitectures via metal organic framework self-sacrificial template strategy is proposed. By employing this method, we can successfully synthesize uniform NiFe2O4, ZnFe2O4, and CoFe2O4 hollow architectures that are hierarchically assembled by nanoparticles. When these hollow microcubes were tested as anode for lithium ion batteries, good rate capability and long-term cycling stability can be achieved. For example, high specific capacities of 636, 449, and 380 mA h g(-1) were depicted by NiFe2O4, ZnFe2O4, and CoFe2O4, respectively, at a high current density of 8.0 A g(-1). NiFe2O4 exhibits high specific capacities of 841 and 447 mA h g(-1) during the 100th cycle when it was tested at current densities of 1.0 and 5.0 A g(-1), respectively. Discharge capacities of 390 and 290 mA h g(-1) were delivered by the ZnFe2O4 and CoFe2O4, respectively, during the 100th cycle at 5.0 A g(-1).

  13. General Approach for MOF-Derived Porous Spinel AFe2O4 Hollow Structures and Their Superior Lithium Storage Properties.

    PubMed

    Yu, Hong; Fan, Haosen; Yadian, Boluo; Tan, Huiteng; Liu, Weiling; Hng, Huey Hoon; Huang, Yizhong; Yan, Qingyu

    2015-12-01

    A general and simple approach for large-scale synthesis of porous hollow spinel AFe2O4 nanoarchitectures via metal organic framework self-sacrificial template strategy is proposed. By employing this method, we can successfully synthesize uniform NiFe2O4, ZnFe2O4, and CoFe2O4 hollow architectures that are hierarchically assembled by nanoparticles. When these hollow microcubes were tested as anode for lithium ion batteries, good rate capability and long-term cycling stability can be achieved. For example, high specific capacities of 636, 449, and 380 mA h g(-1) were depicted by NiFe2O4, ZnFe2O4, and CoFe2O4, respectively, at a high current density of 8.0 A g(-1). NiFe2O4 exhibits high specific capacities of 841 and 447 mA h g(-1) during the 100th cycle when it was tested at current densities of 1.0 and 5.0 A g(-1), respectively. Discharge capacities of 390 and 290 mA h g(-1) were delivered by the ZnFe2O4 and CoFe2O4, respectively, during the 100th cycle at 5.0 A g(-1). PMID:26572743

  14. Nanoparticles for neuroimaging

    NASA Astrophysics Data System (ADS)

    Re, F.; Moresco, R.; Masserini, M.

    2012-02-01

    The advent of nanotechnology has introduced a variety of novel exciting possibilities into the medical and clinical field. Nanoparticles, ultra-small object sized between 100 and 1 nm, are promising diagnostic tools for various diseases among other devices, thanks to the possibility of their functionalization allowing the selective targeting of organs, tissues and cells and to facilitate their transport to primary target organs. However, brain targeting represents a still unresolved challenge due to the presence of the blood-brain barrier, a tightly packed layer of endothelial cells that prevents unwanted substances entering the central nervous system. We review a range of nanoparticles suitable for in vivo diagnostic imaging of neurodegenerative diseases and brain disorders, highlighting the possibility to potentially increase their efficiency and kinetics of brain-targeting. We also review a range of imaging techniques with an emphasis on most recently introduced molecular imaging modalities, their current status and future potential.

  15. Graphene stabilized ultra-small CuNi nanocomposite with high activity and recyclability toward catalysing the reduction of aromatic nitro-compounds

    NASA Astrophysics Data System (ADS)

    Fang, Hao; Wen, Ming; Chen, Hanxing; Wu, Qingsheng; Li, Weiying

    2015-12-01

    Nowadays, it is of great significance and a challenge to design a noble-metal-free catalyst with high activity and a long lifetime for the reduction of aromatic nitro-compounds. Here, a 2D structured nanocomposite catalyst with graphene supported CuNi alloy nanoparticles (NPs) is prepared, and is promising for meeting the requirements of green chemistry. In this graphene/CuNi nanocomposite, the ultra-small CuNi nanoparticles (~2 nm) are evenly anchored on graphene sheets, which is not only a breakthrough in the structures, but also brings about an outstanding performance in activity and stability. Combined with a precise optimization of the alloy ratios, the reaction rate constant of graphene/Cu61Ni39 reached a high level of 0.13685 s-1, with a desirable selectivity as high as 99% for various aromatic nitro-compounds. What's more, the catalyst exhibited a unprecedented long lifetime because it could be recycled over 25 times without obvious performance decay or even a morphology change. This work showed the promise and great potential of noble-metal-free catalysts in green chemistry.Nowadays, it is of great significance and a challenge to design a noble-metal-free catalyst with high activity and a long lifetime for the reduction of aromatic nitro-compounds. Here, a 2D structured nanocomposite catalyst with graphene supported CuNi alloy nanoparticles (NPs) is prepared, and is promising for meeting the requirements of green chemistry. In this graphene/CuNi nanocomposite, the ultra-small CuNi nanoparticles (~2 nm) are evenly anchored on graphene sheets, which is not only a breakthrough in the structures, but also brings about an outstanding performance in activity and stability. Combined with a precise optimization of the alloy ratios, the reaction rate constant of graphene/Cu61Ni39 reached a high level of 0.13685 s-1, with a desirable selectivity as high as 99% for various aromatic nitro-compounds. What's more, the catalyst exhibited a unprecedented long lifetime

  16. Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe3O4 nanoparticle rings

    NASA Astrophysics Data System (ADS)

    Takeno, Yumu; Murakami, Yasukazu; Sato, Takeshi; Tanigaki, Toshiaki; Park, Hyun Soon; Shindo, Daisuke; Ferguson, R. Matthew; Krishnan, Kannan M.

    2014-11-01

    This study reports on the correlation between crystal orientation and magnetic flux distribution of Fe3O4 nanoparticles in the form of self-assembled rings. High-resolution transmission electron microscopy demonstrated that the nanoparticles were single-crystalline, highly monodispersed, (25 nm average diameter), and showed no appreciable lattice imperfections such as twins or stacking faults. Electron holography studies of these superparamagnetic nanoparticle rings indicated significant fluctuations in the magnetic flux lines, consistent with variations in the magnetocrystalline anisotropy of the nanoparticles. The observations provide useful information for a deeper understanding of the micromagnetics of ultrasmall nanoparticles, where the magnetic dipolar interaction competes with the magnetic anisotropy.

  17. Synthesis and characterisation of biologically compatible TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Cheyne, Richard W.; Smith, Tim Ad; Trembleau, Laurent; McLaughlin, Abbie C.

    2011-06-01

    We describe for the first time the synthesis of biocompatible TiO2 nanoparticles containing a functional NH2 group which are easily dispersible in water. The synthesis of water dispersible TiO2 nanoparticles coated with mercaptosuccinic acid is also reported. We show that it is possible to exchange the stearic acid from pre-synthesised fatty acid-coated anatase 5-nm nanoparticles with a range of organic ligands with no change in the size or morphology. With further organic functionalisation, these nanoparticles could be used for medical imaging or to carry cytotoxic radionuclides for radioimmunotherapy where ultrasmall nanoparticles will be essential for rapid renal clearance.

  18. Studies on ultrasmall bacteria in relation to the presence of bacteria in the stratosphere

    NASA Astrophysics Data System (ADS)

    Alshammari, Fawaz; Wainwright, Milton; Alabri, Khalid; Alharbi, Sulamain A.

    2011-04-01

    Recent studies confirm that bacteria exist in the stratosphere. It is generally assumed that these bacteria are exiting from Earth, although it is possible that some are incoming from space. Most stratospheric bacterial isolates belong to the spore-forming genus Bacillus, although non-spore formers have also been isolated. Theoretically, the smaller a bacterium is, the more likely it is to be carried from Earth to the stratosphere. Ultrasmall bacteria have been frequently isolated from Earth environments, but not yet from the stratosphere. This is an anomalous situation, since we would expect such small bacteria to be over represented in the stratosphere-microflora. Here, we show that ultrasmall bacteria are present in the environment on Earth (i.e. in seawater and rainwater) and discuss the paradox of why they have not been isolated from the stratosphere.

  19. An insight into the metabolic responses of ultra-small superparamagnetic particles of iron oxide using metabonomic analysis of biofluids

    NASA Astrophysics Data System (ADS)

    Feng, Jianghua; Liu, Huili; Zhang, Limin; Bhakoo, Kishore; Lu, Lehui

    2010-10-01

    Ultra-small superparamagnetic particles of iron oxides (USPIO) have been developed as intravenous organ/tissue-targeted contrast agents to improve magnetic resonance imaging (MRI) in vivo. However, their potential toxicity and effects on metabolism have attracted particular attention. In the present study, uncoated and dextran-coated USPIO were investigated by analyzing both rat urine and plasma metabonomes using high-resolution NMR-based metabonomic analysis in combination with multivariate statistical analysis. The wealth of information gathered on the metabolic profiles from rat urine and plasma has revealed subtle metabolic changes in response to USPIO administration. The metabolic changes include the elevation of urinary α-hydroxy-n-valerate, o- and p-HPA, PAG, nicotinate and hippurate accompanied by decreases in the levels of urinary α-ketoglutarate, succinate, citrate, N-methylnicotinamide, NAG, DMA, allantoin and acetate following USPIO administration. The changes associated with USPIO administration included a gradual increase in plasma glucose, N-acetyl glycoprotein, saturated fatty acid, citrate, succinate, acetate, GPC, ketone bodies (β-hydroxybutyrate, acetone and acetoacetate) and individual amino acids, such as phenylalanine, lysine, isoleucine, glycine, glutamine and glutamate and a gradual decrease of myo-inositol, unsaturated fatty acid and triacylglycerol. Hence USPIO administration effects are reflected in changes in a number of metabolic pathways including energy, lipid, glucose and amino acid metabolism. The size- and surface chemistry-dependent metabolic responses and possible toxicity were observed using NMR analysis of biofluids. These changes may be attributed to the disturbances of hepatic, renal and cardiac functions following USPIO administrations. The potential biotoxicity can be derived from metabonomic analysis and serum biochemistry analysis. Metabonomic strategy offers a promising approach for the detection of subtle

  20. Ultrasmall particle detection using a submicron Hall sensor

    SciTech Connect

    Kazakova, O.; Gallop, J.; Panchal, V.; See, P.; Cox, D. C.; Spasova, M.; Cohen, L. F.

    2010-05-15

    We demonstrate detection of a single FePt nanoparticle (diameter 150 nm, moment {approx}10{sup 7} {mu}{sub B}) using an ultrasensitive InSb Hall sensor with the bar lateral width of 600 nm. The white noise of a typical nanodevice, S{sub V}{sup 1/2{approx_equal}}28 nV/{radical}Hz, is limited only by two-terminal resistance of the voltage leads which results in a minimum field sensitivity of the device B{sub min}=0.87 {mu}T/{radical}Hz. To detect a single FePt bead, we employed a phase-sensitive method based on measuring the ac susceptibility change in a bead when exposed to a switched dc magnetic field. Such nano-Hall devices, enabling detection of potentially even smaller moments, are of considerable significance both for nanomagnetic metrology and high sensitivity biological and environmental detectors.

  1. Fabrication of Ultrasmall High-Quality Bi2Sr2CaCu2O8+δ Intrinsic Josephson Junctions

    NASA Astrophysics Data System (ADS)

    Matsumoto, Tetsuro; Kashiwaya, Hiromi; Shibata, Hajime; Eisaki, Hiroshi; Yoshida, Yoshiyuki; Kashiwaya, Satoshi

    2008-10-01

    The fabrication of ultrasmall high-quality intrinsic Josephson junctions (IJJs) using a cuprate superconductor is critical for the realization of a qubit. We investigated the mechanism of damage induced by a Ga+ beam in a Bi2Sr2CaCu2O8+δ IJJ during focused ion beam (FIB) processing. On the basis of the results, we developed a process that allowed the successful fabrication of an ultrasmall and high-quality IJJ. The damage induced by the FIB is reduced by restricting the direction of the Ga+ beam so that the junction area is not directly irradiated by the ion beam. The fabricated ultrasmall IJJ device has a junction area of 0.3 µm2 and shows excellent current-voltage characteristics.

  2. Fabrication and characterization of well-aligned plasmonic nanopillars with ultrasmall separations

    PubMed Central

    2014-01-01

    We show the fabrication of well-aligned gold and silver nanopillars with various array parameters via interference lithography followed by ion beam milling and compare the etching rates of these two metallic materials. Silver is suitable for fabricating ultrafine arrays with ultrasmall separations due to high milling rates. The optical properties of the fabricated nanopillars are specifically characterized from both normal incidence and oblique incident angles. Tunable surface plasmon resonances are achieved with varying structural parameters. Strong coupling effects are enabled when the separation between adjacent nanopillars is dramatically reduced, leading to useful applications in sensing and waveguiding. PMID:24959111

  3. Vascular and plaque imaging with ultrasmall superparamagnetic particles of iron oxide.

    PubMed

    Alam, Shirjel R; Stirrat, Colin; Richards, Jennifer; Mirsadraee, Saeed; Semple, Scott I K; Tse, George; Henriksen, Peter; Newby, David E

    2015-01-01

    Cardiovascular Magnetic Resonance (CMR) has become a primary tool for non-invasive assessment of cardiovascular anatomy, pathology and function. Existing contrast agents have been utilised for the identification of infarction, fibrosis, perfusion deficits and for angiography. Novel ultrasmall superparamagnetic particles of iron oxide (USPIO) contrast agents that are taken up by inflammatory cells can detect cellular inflammation non-invasively using CMR, potentially aiding the diagnosis of inflammatory medical conditions, guiding their treatment and giving insight into their pathophysiology. In this review we describe the utilization of USPIO as a novel contrast agent in vascular disease. PMID:26381872

  4. Holographic interferometry of ultrasmall-pressure-induced curvature changes of bilayer lipid membranes

    SciTech Connect

    Picard, G.; Schneider-Henriquez, J.E.; Fendler, J.H. )

    1990-01-25

    Two-exposure interferometric holograms have been shown to sensitively report ultrasmall-pressure (10 natm)-induced curvature changes in glyceryl monooleate (GMO) bilayer lipid membranes (BLMs). The number of concentric fringes observed, and hence the lateral distance between the plane of the Teflon and the BLM, increased linearly with increasing transmembrane pressure and led to a value of 1.1 {plus minus} 0.05 dyn/cm for the surface tension of the BLM. BLMs with appreciable Plateau-Gibbs borders have been shown to undergo nonuniform deformation; the bilayer portion is distorted less than the surrounding Plateau-Gibbs border upon the application of a transmembrane pressure gradient.

  5. Magnetic properties, water proton relaxivities, and in-vivo MR images of paramagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Lee, Gang Ho; Chang, Yongmin

    2015-07-01

    In this mini review, magnetic resonance imaging (MRI) contrast agents based on lanthanideoxide (Ln2O3) nanoparticles are described. Ln2O3 (Ln = Gd, Dy, Ho, and Er) nanoparticles are paramagnetic, but show appreciable magnetic moments at room temperature and even at ultrasmall particle diameters. Among Ln2O3 nanoparticles, Gd2O3 nanoparticles show larger longitudinal water proton relaxivity (r1) values than Gd-chelates because of the large amount of Gd in the nanoparticle, and the other Ln2O3 nanoparticles (Ln = Dy, Ho, and Er) show appreciable transverse water proton relaxivity (r2) values. Therefore, Gd2O3 nanoparticles are potential T1 MRI contrast agents while the other Ln2O3 nanoparticles are potential T2 MRI contrast agents at high MR fields.

  6. Influence of calcination temperature on structural and magnetic properties of nanocomposites formed by Co-ferrite dispersed in sol-gel silica matrix using tetrakis(2-hydroxyethyl) orthosilicate as precursor

    PubMed Central

    2011-01-01

    Effects of calcination temperatures varying from 400 to 1000°C on structural and magnetic properties of nanocomposites formed by Co-ferrite dispersed in the sol-gel silica matrix using tetrakis(2-hydroxyethyl) orthosilicate (THEOS) as water-soluble silica precursor have been investigated. Studies carried out using XRD, FT-IR, TEM, STA (TG-DTG-DTA) and VSM techniques. Results indicated that magnetic properties of samples such as superparamagnetism and ferromagnetism showed great dependence on the variation of the crystallinity and particle size caused by the calcination temperature. The crystallization, saturation magnetization Ms and remenant magnetization Mr increased as the calcination temperature increased. But the variation of coercivity Hc was not in accordance with that of Ms and Mr, indicating that Hc is not determined only by the crystallinity and size of CoFe2O4 nanoparticles. TEM images showed spherical nanoparticles dispersed in the silica network with sizes of 10-30 nm. Results showed that the well-established silica network provided nucleation locations for CoFe2O4 nanoparticles to confinement the coarsening and aggregation of nanoparticles. THEOS as silica matrix network provides an ideal nucleation environment to disperse CoFe2O4 nanoparticles and thus to confine them to aggregate and coarsen. By using THEOS as water-soluble silica precursor over the currently used TEOS and TMOS, the organic solvents are not needed owing to the complete solubility of THEOS in water. Synthesized nanocomposites with adjustable particle sizes and controllable magnetic properties make the applicability of Co-ferrite even more versatile. PMID:21486494

  7. Decorating in situ ultrasmall tin particles on crumpled N-doped graphene for lithium-ion batteries with a long life cycle

    NASA Astrophysics Data System (ADS)

    Liu, Lianjun; Huang, Xingkang; Guo, Xiaoru; Mao, Shun; Chen, Junhong

    2016-10-01

    The practical application of Sn, a promising anode material for lithium-ion batteries, is hindered primarily by its huge volume change (up to 260%) upon lithiation. To tackle this obstacle, here we report a facile one-pot method, i.e., pyrolysis of a mixture of GO, SnCl4, and cyanamide at elevated temperatures to create in situ a novel mesoporous structure of Sn@N-doped graphene (Sn@NG). In the constructed architecture, the ultrasmall Sn nanoparticles (2-3 nm) are uniformly embedded in the NG network while the crumpled NG provides good electronic conductivity, abundant defects, high surface area, and large mesopore volume. Due to the combination of these merits, Sn@NG exhibits extremely long-term cycling stability, even at high rates, retaining a capacity of 568 mAh g-1 at 1 A g-1 (90% retention) and 535 mAh g-1 at 2 A g-1 (91.6% retention) after 1000 and 900 cycles, respectively. This performance is superior to that of Sn@G (without N-doping) and Sn//NG prepared using a two-step process with large particle sizes (>30 nm) and uneven dispersion of Sn. The findings from this work will shed light on the design of efficient and stable Sn and other metal-based materials for energy storage and conversion.

  8. Ultrasmall superparamagnetic iron oxides (USPIOs): a future alternative magnetic resonance (MR) contrast agent for patients at risk for nephrogenic systemic fibrosis (NSF)?

    PubMed

    Neuwelt, Edward A; Hamilton, Bronwyn E; Varallyay, Csanad G; Rooney, William R; Edelman, Robert D; Jacobs, Paula M; Watnick, Suzanne G

    2009-03-01

    Gadolinium (Gd) based contrast agents (GBCAs) in magnetic resonance imaging (MRI) are used in daily clinical practice and appear safe in most patients; however, nephrogenic systemic fibrosis (NSF) is a recently recognized severe complication associated with GBCAs. It affects primarily patients with renal disease, such as stage 4 or 5 chronic kidney disease (CKD; glomerular filtration rate <30 ml/min per 1.73 m(2)), acute kidney injury, or kidney and liver transplant recipients with kidney dysfunction. Contrast-enhanced MRI and computed tomography (CT) scans provide important clinical information and influence patient management. An alternative contrast agent is needed to obtain adequate imaging results while avoiding the risk of NSF in this vulnerable patient group. One potential alternative is ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles, which provide enhancement characteristics similar to GBCAs. We review our experience in approximately 150 patients on the potential benefits of the USPIOs ferumoxtran-10 and ferumoxytol. We focus on central nervous system (CNS) MRI but also review imaging of other vascular beds. Safety studies, including USPIO administration (ferumoxytol) as iron supplement therapy in CKD patients on and not on dialysis, suggest that decreased kidney function does not alter the safety profile. We conclude that for both CNS MR imaging and MR angiography, USPIO agents like ferumoxytol are a viable option for patients at risk for NSF.

  9. Active-target T1-weighted MR Imaging of Tiny Hepatic Tumor via RGD Modified Ultra-small Fe3O4 Nanoprobes

    PubMed Central

    Jia, Zhengyang; Song, Lina; Zang, Fengchao; Song, Jiacheng; Zhang, Wei; Yan, Changzhi; Xie, Jun; Ma, Zhanlong; Ma, Ming; Teng, Gaojun; Gu, Ning; Zhang, Yu

    2016-01-01

    Developing ultrasensitive contrast agents for the early detection of malignant tumors in liver is highly demanded. Constructing hepatic tumors specific targeting probes could provide more sensitive imaging information but still faces great challenges. Here we report a novel approach for the synthesis of ultra-small Fe3O4 nanoparticles conjugated with c(RGDyK) and their applications as active-target T1-weighted magnetic resonance imaging (MRI) contrast agent (T1-Fe3O4) for imaging tiny hepatic tumors in vivo. RGD-modified T1-Fe3O4 nanoprobes exhibited high r1 of 7.74 mM-1s-1 and ultralow r2/r1 of 2.8 at 3 T, reflecting their excellent T1 contrast effect at clinically relevant magnetic field. High targeting specificity together with favorable biocompatibility and strong ability to resist against non-specific uptake were evaluated through in vitro studies. Owing to the outstanding properties of tumor angiogenesis targeting with little phagocytosis in liver parenchyma, hepatic tumor as small as 2.2 mm was successfully detected via the T1 contrast enhancement of RGD-modified T1-Fe3O4. It is emphasized that this is the first report on active-target T1 imaging of hepatic tumors, which could not only significantly improve diagnostic sensitivity, but also provide post therapeutic assessments for patients with liver cancer. PMID:27570550

  10. Active-target T1-weighted MR Imaging of Tiny Hepatic Tumor via RGD Modified Ultra-small Fe3O4 Nanoprobes.

    PubMed

    Jia, Zhengyang; Song, Lina; Zang, Fengchao; Song, Jiacheng; Zhang, Wei; Yan, Changzhi; Xie, Jun; Ma, Zhanlong; Ma, Ming; Teng, Gaojun; Gu, Ning; Zhang, Yu

    2016-01-01

    Developing ultrasensitive contrast agents for the early detection of malignant tumors in liver is highly demanded. Constructing hepatic tumors specific targeting probes could provide more sensitive imaging information but still faces great challenges. Here we report a novel approach for the synthesis of ultra-small Fe3O4 nanoparticles conjugated with c(RGDyK) and their applications as active-target T1-weighted magnetic resonance imaging (MRI) contrast agent (T1-Fe3O4) for imaging tiny hepatic tumors in vivo. RGD-modified T1-Fe3O4 nanoprobes exhibited high r1 of 7.74 mM(-1)s(-1) and ultralow r2/r1 of 2.8 at 3 T, reflecting their excellent T1 contrast effect at clinically relevant magnetic field. High targeting specificity together with favorable biocompatibility and strong ability to resist against non-specific uptake were evaluated through in vitro studies. Owing to the outstanding properties of tumor angiogenesis targeting with little phagocytosis in liver parenchyma, hepatic tumor as small as 2.2 mm was successfully detected via the T1 contrast enhancement of RGD-modified T1-Fe3O4. It is emphasized that this is the first report on active-target T1 imaging of hepatic tumors, which could not only significantly improve diagnostic sensitivity, but also provide post therapeutic assessments for patients with liver cancer. PMID:27570550

  11. Synthesis of ultrasmall Li–Mn spinel oxides exhibiting unusual ion exchange, electrochemical, and catalytic properties

    PubMed Central

    Miyamoto, Yumi; Kuroda, Yoshiyuki; Uematsu, Tsubasa; Oshikawa, Hiroyuki; Shibata, Naoya; Ikuhara, Yuichi; Suzuki, Kosuke; Hibino, Mitsuhiro; Yamaguchi, Kazuya; Mizuno, Noritaka

    2015-01-01

    The efficient surface reaction and rapid ion diffusion of nanocrystalline metal oxides have prompted considerable research interest for the development of high functional materials. Herein, we present a novel low-temperature method to synthesize ultrasmall nanocrystalline spinel oxides by controlling the hydration of coexisting metal cations in an organic solvent. This method selectively led to Li–Mn spinel oxides by tuning the hydration of Li+ ions under mild reaction conditions (i.e., low temperature and short reaction time). These particles exhibited an ultrasmall crystallite size of 2.3 nm and a large specific surface area of 371 ± 15 m2 g−1. They exhibited unique properties such as unusual topotactic Li+/H+ ion exchange, high-rate discharge ability, and high catalytic performance for several aerobic oxidation reactions, by creating surface phenomena throughout the particles. These properties differed significantly from those of Li–Mn spinel oxides obtained by conventional solid-state methods. PMID:26456216

  12. Ultrasmall peptides self-assemble into diverse nanostructures: morphological evaluation and potential implications.

    PubMed

    Lakshmanan, Anupama; Hauser, Charlotte A E

    2011-01-01

    In this study, we perform a morphological evaluation of the diverse nanostructures formed by varying concentration and amino acid sequence of a unique class of ultrasmall self-assembling peptides. We modified these peptides by replacing the aliphatic amino acid at the C-aliphatic terminus with different aromatic amino acids. We tracked the effect of introducing aromatic residues on self-assembly and morphology of resulting nanostructures. Whereas aliphatic peptides formed long, helical fibers that entangle into meshes and entrap >99.9% water, the modified peptides contrastingly formed short, straight fibers with a flat morphology. No helical fibers were observed for the modified peptides. For the aliphatic peptides at low concentrations, different supramolecular assemblies such as hollow nanospheres and membrane blebs were found. Since the ultrasmall peptides are made of simple, aliphatic amino acids, considered to have existed in the primordial soup, study of these supramolecular assemblies could be relevant to understanding chemical evolution leading to the origin of life on Earth. In particular, we propose a variety of potential applications in bioengineering and nanotechnology for the diverse self-assembled nanostructures. PMID:22016623

  13. Synthesis of ultrasmall Li-Mn spinel oxides exhibiting unusual ion exchange, electrochemical, and catalytic properties.

    PubMed

    Miyamoto, Yumi; Kuroda, Yoshiyuki; Uematsu, Tsubasa; Oshikawa, Hiroyuki; Shibata, Naoya; Ikuhara, Yuichi; Suzuki, Kosuke; Hibino, Mitsuhiro; Yamaguchi, Kazuya; Mizuno, Noritaka

    2015-10-12

    The efficient surface reaction and rapid ion diffusion of nanocrystalline metal oxides have prompted considerable research interest for the development of high functional materials. Herein, we present a novel low-temperature method to synthesize ultrasmall nanocrystalline spinel oxides by controlling the hydration of coexisting metal cations in an organic solvent. This method selectively led to Li-Mn spinel oxides by tuning the hydration of Li(+) ions under mild reaction conditions (i.e., low temperature and short reaction time). These particles exhibited an ultrasmall crystallite size of 2.3 nm and a large specific surface area of 371 ± 15 m(2) g(-1). They exhibited unique properties such as unusual topotactic Li(+)/H(+) ion exchange, high-rate discharge ability, and high catalytic performance for several aerobic oxidation reactions, by creating surface phenomena throughout the particles. These properties differed significantly from those of Li-Mn spinel oxides obtained by conventional solid-state methods.

  14. Morphological characterization of carbon-nanofiber-reinforced epoxy nanocomposites using ultra-small angle scattering

    SciTech Connect

    Justice, R.S.; Anderson, D.P.; Brown, J.M.; Arlen, M.J.; Colleary, A.J.; Lafdi, K.; Schaefer, D.W.

    2010-07-01

    Studies of the properties of nanocomposites reinforced with vapor-grown carbon nanofibers (VGCFs) can be found throughout the literature. Electrical, mechanical, viscoelastic, and rheological properties are just a few of the characteristics that have been well discussed. Although these properties depend on morphology, morphological characterization is rare. Due to its 2-dimensional nature, microscopy is of limited value when analyzing network morphologies. This work will show how the characterization of the three-dimensional geometry and network formation of VGCFs can be determined using ultra-small angle scattering techniques. Ultra-small angle x-ray and neutron scattering (USAXS and USANS) were used to characterize the morphology of carbon nanofibers suspended in epoxy. Using a simplified tube model, we estimate the dimensions of suspended fibers. The assumption of tubular fibers accounts for the increased surface area observed with USAXS that is not accounted for using a solid rod model. Furthermore, USANS was used to search for a structural signature associated with the electrical percolation threshold. USANS extends to longer dimensional scales than USAXS, which measures a smaller range of momentum transfer. To determine the electrical percolation threshold, AC impedance spectroscopy was employed to verify that an electrically conductive, percolated network forms at VGCNF loadings of 0.8% < CNF wt% < 1.2%. These values correlate with the USANS data, where a morphological transition is seen at {approx}1.2% loading.

  15. Ultra-small and broadband polarization splitters based on double-slit interference

    NASA Astrophysics Data System (ADS)

    Sun, Chengwei; Li, Hongyun; Gong, Qihuang; Chen, Jianjun

    2016-03-01

    An ultra-small and broadband polarization splitter is numerically and experimentally demonstrated based on the double-slit interference in a polymer-film-coated double-slit structure. The hybrid slab waveguide (air-polymer-Au) supports both the transverse-magnetic and transverse-electric modes. The incident beam from the back side can excite these two guided modes of orthogonally polarized states in the hybrid structure. By exploiting the difference slit widths and the large mode birefringence, these two guided modes propagate to the opposite directions along the front metal surface. Moreover, the short interference length broadens the operation bandwidth. Experimentally, a polarization splitter with a lateral dimension of only about 1.6 μm and an operation bandwidth of 50 nm is realized. By designing the double-slit structure in a hybrid strip waveguide, the device dimension can be significant downscaled to about 0.3 × 1.3 μm2. Such an ultra-small and broadband polarization splitter may find important applications in the integrated photonic circuits.

  16. Ultrasmall peptides self-assemble into diverse nanostructures: morphological evaluation and potential implications.

    PubMed

    Lakshmanan, Anupama; Hauser, Charlotte A E

    2011-01-01

    In this study, we perform a morphological evaluation of the diverse nanostructures formed by varying concentration and amino acid sequence of a unique class of ultrasmall self-assembling peptides. We modified these peptides by replacing the aliphatic amino acid at the C-aliphatic terminus with different aromatic amino acids. We tracked the effect of introducing aromatic residues on self-assembly and morphology of resulting nanostructures. Whereas aliphatic peptides formed long, helical fibers that entangle into meshes and entrap >99.9% water, the modified peptides contrastingly formed short, straight fibers with a flat morphology. No helical fibers were observed for the modified peptides. For the aliphatic peptides at low concentrations, different supramolecular assemblies such as hollow nanospheres and membrane blebs were found. Since the ultrasmall peptides are made of simple, aliphatic amino acids, considered to have existed in the primordial soup, study of these supramolecular assemblies could be relevant to understanding chemical evolution leading to the origin of life on Earth. In particular, we propose a variety of potential applications in bioengineering and nanotechnology for the diverse self-assembled nanostructures.

  17. Glutathione-coated luminescent gold nanoparticles: a surface ligand for minimizing serum protein adsorption.

    PubMed

    Vinluan, Rodrigo D; Liu, Jinbin; Zhou, Chen; Yu, Mengxiao; Yang, Shengyang; Kumar, Amit; Sun, Shasha; Dean, Andrew; Sun, Xiankai; Zheng, Jie

    2014-08-13

    Ultrasmall glutathione-coated luminescent gold nanoparticles (GS-AuNPs) are known for their high resistance to serum protein adsorption. Our studies show that these NPs can serve as surface ligands to significantly enhance the physiological stability and lower the serum protein adsorption of superparamagnetic iron oxide nanoparticles (SPIONs), in addition to rendering the NPs the luminescence property. After the incorporation of GS-AuNPs onto the surface of SPIONs to form the hybrid nanoparticles (HBNPs), these SPIONs' protein adsorption was about 10-fold lower than those of the pure glutathione-coated SPIONs suggesting that GS-AuNPs are capable of providing a stealth effect against serum proteins.

  18. 201Tl+-labelled Prussian blue nanoparticles as contrast agents for SPECT scintigraphy

    NASA Astrophysics Data System (ADS)

    Perrier, M.; Busson, M.; Massasso, G.; Long, J.; Boudousq, V.; Pouget, J.-P.; Peyrottes, S.; Perigaud, Ch.; Porredon-Guarch, C.; de Lapuente, J.; Borras, M.; Larionova, J.; Guari, Y.

    2014-10-01

    Prussian blue (PB) and its analogues on the nanometric scale are exciting nano-objects that combine the advantages of molecular-based materials and nanochemistry. Herein, we demonstrate that ultra-small PB nanoparticles of 2-3 nm can be easily labelled with radioactive 201Tl+ to obtain new nanoprobes as radiotracers for 201-thallium-based imaging.Prussian blue (PB) and its analogues on the nanometric scale are exciting nano-objects that combine the advantages of molecular-based materials and nanochemistry. Herein, we demonstrate that ultra-small PB nanoparticles of 2-3 nm can be easily labelled with radioactive 201Tl+ to obtain new nanoprobes as radiotracers for 201-thallium-based imaging. Electronic supplementary information (ESI) available: Experimental details and procedures, toxicological data, PXRD, TEM images, kinetics and adsorption isotherms, SPECT/CT images, Tl+ captation profiles. See DOI: 10.1039/c4nr03044c

  19. Magnetic resonance imaging of ultrasmall superparamagnetic iron oxide-labeled exosomes from stem cells: a new method to obtain labeled exosomes

    PubMed Central

    Busato, Alice; Bonafede, Roberta; Bontempi, Pietro; Scambi, Ilaria; Schiaffino, Lorenzo; Benati, Donatella; Malatesta, Manuela; Sbarbati, Andrea; Marzola, Pasquina; Mariotti, Raffaella

    2016-01-01

    Purpose Recent findings indicate that the beneficial effects of adipose stem cells (ASCs), reported in several neurodegenerative experimental models, could be due to their paracrine activity mediated by the release of exosomes. The aim of this study was the development and validation of an innovative exosome-labeling protocol that allows to visualize them with magnetic resonance imaging (MRI). Materials and methods At first, ASCs were labeled using ultrasmall superparamagnetic iron oxide nanoparticles (USPIO, 4–6 nm), and optimal parameters to label ASCs in terms of cell viability, labeling efficiency, iron content, and magnetic resonance (MR) image contrast were investigated. Exosomes were then isolated from labeled ASCs using a standard isolation protocol. The efficiency of exosome labeling was assessed by acquiring MR images in vitro and in vivo as well as by determining their iron content. Transmission electron microscopy images and histological analysis were performed to validate the results obtained. Results By using optimized experimental parameters for ASC labeling (200 µg Fe/mL of USPIO and 72 hours of incubation), it was possible to label 100% of the cells, while their viability remained comparable to unlabeled cells; the detection limit of MR images was of 102 and 2.5×103 ASCs in vitro and in vivo, respectively. Exosomes isolated from previously labeled ASCs retain nanoparticles, as demonstrated by transmission electron microscopy images. The detection limit by MRI was 3 µg and 5 µg of exosomes in vitro and in vivo, respectively. Conclusion We report a new approach for labeling of exosomes by USPIO that allows detection by MRI while preserving their morphology and physiological characteristics. PMID:27330291

  20. Ultra-small time-delay estimation via a weak measurement technique with post-selection

    NASA Astrophysics Data System (ADS)

    Fang, Chen; Huang, Jing-Zheng; Yu, Yang; Li, Qinzheng; Zeng, Guihua

    2016-09-01

    Weak measurement is a novel technique for parameter estimation with higher precision. In this paper we develop a general theory for the parameter estimation based on a weak measurement technique with arbitrary post-selection. The weak-value amplification model and the joint weak measurement model are two special cases in our theory. Applying the developed theory, time-delay estimation is investigated in both theory and experiments. The experimental results show that when the time delay is ultra-small, the joint weak measurement scheme outperforms the weak-value amplification scheme, and is robust against not only misalignment errors but also the wavelength dependence of the optical components. These results are consistent with theoretical predictions that have not been previously verified by any experiment.

  1. Ultrasmall-angle X-ray scattering analysis of photonic crystal structure

    SciTech Connect

    Abramova, V. V.; Sinitskii, A. S.; Grigor'eva, N. A.; Grigor'ev, S. V.; Belov, D. V.; Petukhov, A. V.; Mistonov, A. A.; Vasil'eva, A. V.; Tret'yakov, Yu. D.

    2009-07-15

    The results of an ultrasmall-angle X-ray scattering study of iron(III) oxide inverse opal thin films are presented. The photonic crystals examined are shown to have fcc structure with amount of stacking faults varying among the samples. The method used in this study makes it possible to easily distinguish between samples with predominantly twinned fcc structure and nearly perfect fcc stacking. The difference observed between samples fabricated under identical conditions is attributed to random layer stacking in the self-assembled colloidal crystals used as templates for fabricating the inverse opals. The present method provides a versatile tool for analyzing photonic crystal structure in studies of inverse opals made of various materials, colloidal crystals, and three-dimensional photonic crystals of other types.

  2. Ultra-small and anionic starch nanospheres: formation and vitro thrombolytic behavior study.

    PubMed

    Huang, Yinjuan; Ding, Shenglong; Liu, Mingzhu; Gao, Chunmei; Yang, Jinlong; Zhang, Xinjie; Ding, Bin

    2013-07-25

    This paper is considered as the first report on the investigation of nattokinase (NK) release from anionic starch nanospheres. The ultra-small and anionic starch nanospheres were prepared by the method of reverse micro-emulsion crosslinking in this work. Starch nanospheres were characterized through Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). Effects of preparation conditions on particle size were studied. The cytotoxicity, biodegradable and vitro thrombolytic behaviors of nattokinase (NK) loaded anionic starch nanospheres were also studied. The results showed that the anionic starch nanospheres are non-toxic, biocompatible and biodegradable. Moreover, the anionic starch nanospheres can protect NK from fast biodegradation hence prolongs the circulation in vivo and can reduce the risk of acute hemorrhage complication by decreasing the thrombolysis rate.

  3. Reactions in ultra-small droplets by tip-assisted chemistry.

    PubMed

    Guardingo, M; Busqué, F; Ruiz-Molina, D

    2016-10-01

    The confinement of chemical reactions within small droplets has received much attention in the last few years. This approach has been proved successful for the in-depth study of naturally occurring chemical processes as well as for the synthesis of different sets of nanomaterials with control over their size, shape and properties. Different approaches such as the use of self-contained structures or microfluidic generated droplets have been followed over the years with success. However, novel approaches have emerged during the last years based on the deposition of femtolitre-sized droplets on surfaces using tip-assisted lithographic methods. In this feature article, we review the advances made towards the use of these ultra-small droplets patterned on surfaces as confined nano-reactors.

  4. Amorphous RE–Fe–B–Na colloidal nanoparticles: High temperature solution synthesis and magnetic properties

    SciTech Connect

    Jia, Li-Ping; Yan, Bing

    2015-04-15

    Graphical abstract: RE–Fe–B–Na (RE = Nd–Er) colloidal nanoparticles by high-temperature solution synthesis are ultra-small monodisperse and air-stable amorphous, whose size and magnetic dependence are studied. - Highlights: • RE–Fe–B–Na nanoparticles are obtained by high-temperature solution synthesis. • These colloidal nanoparticles are monodisperse and size controlled. • The magnetism dependence and possible magnetic coupling mechanism are studied. - Abstract: RE–Fe–B–Na (RE = Nd–Er) colloidal nanoparticles are prepared by high-temperature solution synthesis. These nanoparticles are ultra-small monodisperse, air-stable and amorphous, whose particle size and magnetic property are characterized by transmission electron microscope and superconducting quantum interference device. Taking Nd–Fe–B–Na nanoparticle as an example, it is found that the particle size can be controlled in less than 7 nm. Besides, the magnetic properties of RE–Fe–B–Na colloidal nanoparticles can be compared for different rare earth elements. Based on the bulk ferromagnetic coupling, other possible magnetic coupling mechanism is discussed.

  5. Novel hybrid multifunctional magnetoelectric porous composite films

    NASA Astrophysics Data System (ADS)

    Martins, P.; Gonçalves, R.; Lopes, A. C.; Venkata Ramana, E.; Mendiratta, S. K.; Lanceros-Mendez, S.

    2015-12-01

    Novel multifunctional porous films have been developed by the integration of magnetic CoFe2O4 (CFO) nanoparticles into poly(vinylidene fluoride)-Trifuoroethylene (P(VDF-TrFE)), taking advantage of the synergies of the magnetostrictive filler and the piezoelectric polymer. The porous films show a piezoelectric response with an effective d33 coefficient of -22 pC/N-1, a maximum magnetization of 12 emu g-1 and a maximum magnetoelectric coefficient of 9 mV cm-1 Oe-1. In this way, a multifunctional membrane has been developed suitable for advanced applications ranging from biomedical to water treatment.

  6. Multifunctional wood materials with magnetic, superhydrophobic and anti-ultraviolet properties

    NASA Astrophysics Data System (ADS)

    Gan, Wentao; Gao, Likun; Sun, Qingfeng; Jin, Chunde; Lu, Yun; Li, Jian

    2015-03-01

    Multifunctional wood materials with magnetic, superhydrophobic and anti-ultraviolet properties were obtained successfully by precipitated CoFe2O4 nanoparticles on the wood surface and then treated with a layer of octadecyltrichlorosilane (OTS). The as-fabricated wood composites exhibited excellent magnetic property and the water contact angle of the OTS-modified magnetic wood surface reached as high as 150°, revealed the superhydrophobic property. Moreover, accelerated aging tests suggested that the treated wood composites also have an excellent anti-ultraviolet property.

  7. Size dependence of magnetorheological properties of cobalt ferrite ferrofluid

    NASA Astrophysics Data System (ADS)

    Radhika, B.; Sahoo, Rasmita; Srinath, S.

    2015-06-01

    Cobalt Ferrite nanoparticles were synthesized using co-precipitation method at reaction temperatures of 40°C and 80°C. X-Ray diffraction studies confirm cubic phase formation. The average crystallite sizes were found to be ˜30nm and ˜48nm for 40°C sample and 80°C sample respectively. Magnetic properties measured using vibrating sample magnetometer show higher coercivety and magnetization for sample prepared at 80°C. Magnetorheological properties of CoFe2O4 ferrofluids were measured and studied.

  8. Size dependence of magnetorheological properties of cobalt ferrite ferrofluid

    SciTech Connect

    Radhika, B.; Sahoo, Rasmita; Srinath, S.

    2015-06-24

    Cobalt Ferrite nanoparticles were synthesized using co-precipitation method at reaction temperatures of 40°C and 80°C. X-Ray diffraction studies confirm cubic phase formation. The average crystallite sizes were found to be ∼30nm and ∼48nm for 40°C sample and 80°C sample respectively. Magnetic properties measured using vibrating sample magnetometer show higher coercivety and magnetization for sample prepared at 80°C. Magnetorheological properties of CoFe2O4 ferrofluids were measured and studied.

  9. Atomically Precise Colloidal Metal Nanoclusters and Nanoparticles: Fundamentals and Opportunities.

    PubMed

    Jin, Rongchao; Zeng, Chenjie; Zhou, Meng; Chen, Yuxiang

    2016-09-28

    Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1-3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the stability, metal-ligand interfacial bonding, ligand assembly on particle surfaces, aesthetic structural patterns, periodicities, and emergence of the metallic state) and to develop a range of potential applications such as in catalysis, biomedicine, sensing, imaging, optics, and energy conversion. Although most of the research activity currently focuses on thiolate-protected gold nanoclusters, important progress has also been achieved in other ligand-protected gold, silver, and bimetal (or alloy) nanoclusters. All of these types of unique nanoparticles will bring unprecedented opportunities, not only in understanding the fundamental questions of nanoparticles but also in opening up new horizons for scientific studies of nanoparticles. PMID:27585252

  10. Atomically Precise Colloidal Metal Nanoclusters and Nanoparticles: Fundamentals and Opportunities.

    PubMed

    Jin, Rongchao; Zeng, Chenjie; Zhou, Meng; Chen, Yuxiang

    2016-09-28

    Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1-3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the stability, metal-ligand interfacial bonding, ligand assembly on particle surfaces, aesthetic structural patterns, periodicities, and emergence of the metallic state) and to develop a range of potential applications such as in catalysis, biomedicine, sensing, imaging, optics, and energy conversion. Although most of the research activity currently focuses on thiolate-protected gold nanoclusters, important progress has also been achieved in other ligand-protected gold, silver, and bimetal (or alloy) nanoclusters. All of these types of unique nanoparticles will bring unprecedented opportunities, not only in understanding the fundamental questions of nanoparticles but also in opening up new horizons for scientific studies of nanoparticles.

  11. Simultaneously targeted imaging cytoplasm and nucleus in living cell by biomolecules capped ultra-small GdOF nanocrystals.

    PubMed

    Yan, Jin; He, Wangxiao; Li, Na; Yu, Meng; Du, Yaping; Lei, Bo; Ma, Peter X

    2015-08-01

    Simultaneously targeted imaging cytoplasm and nucleus in living cell by just one photoluminescent nanocrystals has been a giant challenge in nanobiotechnology and nanomedicine. Herein we report a novel Arg-Gly-Asp peptide (RGD) or cysteine (Cys) functionalized ultra-small GdOF nanocrystals for simultaneously targeted imaging cell cytoplasm and nucleus. As-prepared RGD@GdOF and Cys@GdOF nanocrystals possessed high water dispersibility, ultra-small size (about 5 nm) and double emissions (545 nm and 587 nm) with high quantum yield. Such functionalized nanocrystals presented high cellular biocompatibility and were successfully used to label living cells with very high signal to noise ratio. The living cells cytoplasm and nucleus (cancer cells and stem cells) could be imaged simultaneously through the mergence of green and red emission of nanocrystals, based on mechanism of fluorescent intensity difference. These functionalized nanocrystals also exhibited significantly higher photostability and brightness as compared to dyes. Such the ultra-small size, high photostability and intensity, double emissions, excellent biocompatibility and targeted ability, make as-prepared functionalized nanocrystals particularly promising for cellular and molecular-level bioimaging applications.

  12. Ultrasmall glutathione-protected gold nanoclusters as next generation radiotherapy sensitizers with high tumor uptake and high renal clearance.

    PubMed

    Zhang, Xiao-Dong; Luo, Zhentao; Chen, Jie; Song, Shasha; Yuan, Xun; Shen, Xiu; Wang, Hao; Sun, Yuanming; Gao, Kai; Zhang, Lianfeng; Fan, Saijun; Leong, David Tai; Guo, Meili; Xie, Jianping

    2015-01-01

    Radiotherapy is often the most straightforward first line cancer treatment for solid tumors. While it is highly effective against tumors, there is also collateral damage to healthy proximal tissues especially with high doses. The use of radiosensitizers is an effective way to boost the killing efficacy of radiotherapy against the tumor while drastically limiting the received dose and reducing the possible damage to normal tissues. Here, we report the design and application of a good radiosensitizer by using ultrasmall Au(29-43)(SG)(27-37) nanoclusters (<2 nm) with a naturally-occurring peptide (e.g., glutathione or GSH) as the protecting shell. The GSH-coated Au(29-43)(SG)(27-37) nanoclusters can escape the RES absorption, leading to a good tumor uptake (~8.1% ID/g at 24 h post injection). As a result, the as-designed Au nanoclusters led to a strong enhancement for radiotherapy, as well as a negligible damage to normal tissues. After the treatment, the ultrasmall Au(29-43)(SG)(27-37) nanoclusters can be efficiently cleared by the kidney, thereby avoiding potential long-term side-effects caused by the accumulation of gold atoms in the body. Our data suggest that the ultrasmall peptide-protected Au nanoclusters are a promising radiosensitizer for cancer radiotherapy. PMID:25727895

  13. Ultrasmall Glutathione-Protected Gold Nanoclusters as Next Generation Radiotherapy Sensitizers with High Tumor Uptake and High Renal Clearance

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Dong; Luo, Zhentao; Chen, Jie; Song, Shasha; Yuan, Xun; Shen, Xiu; Wang, Hao; Sun, Yuanming; Gao, Kai; Zhang, Lianfeng; Fan, Saijun; Leong, David Tai; Guo, Meili; Xie, Jianping

    2015-03-01

    Radiotherapy is often the most straightforward first line cancer treatment for solid tumors. While it is highly effective against tumors, there is also collateral damage to healthy proximal tissues especially with high doses. The use of radiosensitizers is an effective way to boost the killing efficacy of radiotherapy against the tumor while drastically limiting the received dose and reducing the possible damage to normal tissues. Here, we report the design and application of a good radiosensitizer by using ultrasmall Au29-43(SG)27-37 nanoclusters (<2 nm) with a naturally-occurring peptide (e.g., glutathione or GSH) as the protecting shell. The GSH-coated Au29-43(SG)27-37 nanoclusters can escape the RES absorption, leading to a good tumor uptake (~8.1% ID/g at 24 h post injection). As a result, the as-designed Au nanoclusters led to a strong enhancement for radiotherapy, as well as a negligible damage to normal tissues. After the treatment, the ultrasmall Au29-43(SG)27-37 nanoclusters can be efficiently cleared by the kidney, thereby avoiding potential long-term side-effects caused by the accumulation of gold atoms in the body. Our data suggest that the ultrasmall peptide-protected Au nanoclusters are a promising radiosensitizer for cancer radiotherapy.

  14. Photocatalytic activities of ultra-small β-FeOOH and TiO{sub 2} heterojunction structure under simulated solar irradiation

    SciTech Connect

    Chowdhury, Mahabubur Ntiribinyange, Mary; Nyamayaro, Kudzanai; Fester, Veruscha

    2015-08-15

    Highlights: • Ultra small β-FeOOH with TiO{sub 2} in heterojunction showed good photocatalytic activity under simulated solar irradiation. • Significant improvement of photocatalytic activity compared to pristine TiO{sub 2}. • The as prepared catalyst decoloured industrial textile effluent within 30 min. - Abstract: Photocatalytic performance of β-FeOOH/TiO{sub 2} heterojunction structure, created from ultra-small β-FeOOH nanorods (2–6 nm diameter) and spherical anatase phase of TiO{sub 2} nanoparticles (∼100 nm), is reported in this study. Three different β-FeOOH mol% of (2, 5 and 10%) β-FeOOH/TiO{sub 2} composite was prepared. 5% β-FeOOH/TiO{sub 2} composite material showed the highest photocatalytic activity. XRD, high temperature XRD, FTIR, TEM, UV–vis diffuse reflectance spectra (DRS) were used to characterise the prepared catalyst. The developed catalyst showed excellent photocatalytic activity in photodegradation of methyl orange (MO) than β-FeOOH and TiO{sub 2} under simulated solar irradiation. Two commercial metal complex dyes and real textile effluent were efficiently photodegraded under identical conditions. The developed catalyst exhibited good recyclability without the need of sintering. No significant loss in efficiency was observed during the recycling cycle. These characteristics highlight the potential application of the developed photocatalyst in textile effluent treatment via photocatalysis. The enhanced photocatalytic activity was attributed to the relative energy band positions and very good electron, e{sup −} and hole, h{sup +} conduction ability of TiO{sub 2} and β-FeOOH particles respectively.

  15. Highly Efficient Antibacterial and Pb(II) Removal Effects of Ag-CoFe2O4-GO Nanocomposite.

    PubMed

    Ma, Shuanglong; Zhan, Sihui; Jia, Yanan; Zhou, Qixing

    2015-05-20

    Ag-CoFe2O4-graphene oxide (Ag-CoFe2O4-GO) nanocomposite was synthesized by doping silver and CoFe2O4 nanoparticles on the surface of GO, which was used to purify both bacteria and Pb(II) contaminated water. The Ag-CoFe2O4-GO nanomaterial was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), cyclic voltammetry (CV), and magnetic property tests. It can be found that Ag-CoFe2O4-GO nanocomposite exhibited excellent antibacterial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus compared with CoFe2O4, Ag-CoFe2O4, and CoFe2O4-GO composite. This superior disinfecting effect was possibly attributed to the combination of GO nanosheets and Ag nanoparticles. Several antibacterial factors including temperature, time, and pH were also investigated. It was obvious that E. coli was more susceptible than S. aureus toward all the four types of nanomaterials. The structural difference of bacterial membranes should be responsible for the resistant discrepancy. We also found that Ag-CoFe2O4-GO inactivated both bacteria in an irreversibly stronger manner than Ag-CoFe2O4 and CoFe2O4-GO. The Pb(II) removal efficiency with all the nanomaterials showed significant dependence on the surface area and zeta potential of the materials. In this work, not only did we demonstrate the simultaneous superior removal efficiency of bacteria and Pb(II) by Ag-CoFe2O4-GO but also the antibacterial mechanism was discussed to have a better understanding of the interaction between Ag-CoFe2O4-GO and bacteria. In a word, taking into consideration the easy magnetic separation, bulk availability, and irreversibly high antibacterial activity of Ag-CoFe2O4-GO, it is the very promising candidate material for advanced antimicrobial or Pb(II) contaminated water treatment.

  16. Hard magnetism in structurally engineered silica nanocomposite.

    PubMed

    Song, Hyon-Min; Zink, Jeffrey I

    2016-09-21

    Creation of structural complexity by simple experimental control will be an attractive approach for the preparation of nanomaterials, as a classical bottom-up method is supplemented by a more efficient and more direct artificial engineering method. In this study, structural manipulation of MCM-41 type mesoporous silica is investigated by generating and imbedding hard magnetic CoFe2O4 nanoparticles into mesoporous silica. Depending on the heating rate and target temperature, mesoporous silica undergoes a transformation in shape to form hollow silica, framed silica with interior voids, or melted silica with intact mesostructures. Magnetism is governed by the major CoFe2O4 phase, and it is affected by antiferromagnetic hematite (α-Fe2O3) and olivine-type cobalt silicate (Co2SiO4), as seen in its paramagnetic behavior at the annealing temperature of 430 °C. The early formation of Co2SiO4 than what is usually observed implies the effect of the partial substitution of Fe in the sites of Co. Under slow heating (2.5 °C min(-1)) mesostructures are preserved, but with significantly smaller mesopores (d100 = 1.5 nm). In addition, nonstoichiometric CoxFe1-xO with metal vacancies at 600 °C, and spinel Co3O4 at 700 °C accompany major CoFe2O4. The amorphous nature of silica matrix is thought to contribute significantly to these structurally diverse and rich phases, enabled by off-stoichiometry between Si and O, and accelerated by the diffusion of metal cations into SiO4 polyhedra at an elevated temperature. PMID:27537252

  17. Hard magnetism in structurally engineered silica nanocomposite.

    PubMed

    Song, Hyon-Min; Zink, Jeffrey I

    2016-09-21

    Creation of structural complexity by simple experimental control will be an attractive approach for the preparation of nanomaterials, as a classical bottom-up method is supplemented by a more efficient and more direct artificial engineering method. In this study, structural manipulation of MCM-41 type mesoporous silica is investigated by generating and imbedding hard magnetic CoFe2O4 nanoparticles into mesoporous silica. Depending on the heating rate and target temperature, mesoporous silica undergoes a transformation in shape to form hollow silica, framed silica with interior voids, or melted silica with intact mesostructures. Magnetism is governed by the major CoFe2O4 phase, and it is affected by antiferromagnetic hematite (α-Fe2O3) and olivine-type cobalt silicate (Co2SiO4), as seen in its paramagnetic behavior at the annealing temperature of 430 °C. The early formation of Co2SiO4 than what is usually observed implies the effect of the partial substitution of Fe in the sites of Co. Under slow heating (2.5 °C min(-1)) mesostructures are preserved, but with significantly smaller mesopores (d100 = 1.5 nm). In addition, nonstoichiometric CoxFe1-xO with metal vacancies at 600 °C, and spinel Co3O4 at 700 °C accompany major CoFe2O4. The amorphous nature of silica matrix is thought to contribute significantly to these structurally diverse and rich phases, enabled by off-stoichiometry between Si and O, and accelerated by the diffusion of metal cations into SiO4 polyhedra at an elevated temperature.

  18. Fabrication and hyperthermia effect of magnetic functional fluids based on amorphous particles

    NASA Astrophysics Data System (ADS)

    Yang, Chuncheng; Bian, Xiufang; Qin, Jingyu; Guo, Tongxiao; Zhao, Shuchun

    2015-03-01

    An experimental study conducted on the preparation and hyperthermia effect of magnetic functional fluids based on Fe73.5Nb3Cu1Si13.5B9 amorphous particles, CoFe2O4 nanoparticles and Fe3O4 nanoparticles dispersed in water is presented. Scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and vibrating sample magnetometer methods have been used to characterize the morphology, structure and magnetic property of the amorphous particles. It is disclosed that the Fe73.5Nb3Cu1Si13.5B9 particles are still amorphous after being milled for 48 h. Moreover, the saturation magnetization of metallic glass particles is approximately 75% and 50% larger than that of CoFe2O4 nanoparticles and Fe3O4 nanoparticles, respectively. The hyperthermia experiment results show that when alternating electrical current is 150 A, the temperature of the functional fluids based on amorphous particles could rise to 33 °C in 1500 s. When the current is 300 A, the final stable temperature could reach to 60 °C. This study demonstrates that the Fe73.5Nb3Cu1Si13.5B9 magnetic functional fluids may have potential on biomedical applications.

  19. Bio-NCs - the marriage of ultrasmall metal nanoclusters with biomolecules

    NASA Astrophysics Data System (ADS)

    Goswami, Nirmal; Zheng, Kaiyuan; Xie, Jianping

    2014-10-01

    Ultrasmall metal nanoclusters (NCs) have attracted increasing attention due to their fascinating physicochemical properties. Today, functional metal NCs are finding growing acceptance in biomedical applications. To achieve a better performance in biomedical applications, metal NCs can be interfaced with biomolecules, such as proteins, peptides, and DNA, to form a new class of biomolecule-NC composites (or bio-NCs in short), which typically show synergistic or novel physicochemical and physiological properties. This feature article focuses on the recent studies emerging at the interface of metal NCs and biomolecules, where the interactions could impart unique physicochemical properties to the metal NCs, as well as mutually regulate biological functions of the bio-NCs. In this article, we first provide a broad overview of key concepts and developments in the novel biomolecule-directed synthesis of metal NCs. A special focus is placed on the key roles of biomolecules in metal NC synthesis. In the second part, we describe how the encapsulated metal NCs affect the structure and function of biomolecules. Followed by that, we discuss several unique synergistic effects observed in the bio-NCs, and illustrate them with examples highlighting their potential biomedical applications. Continued interdisciplinary efforts are required to build up in-depth knowledge about the interfacial chemistry and biology of bio-NCs, which could further pave their ways toward biomedical applications.

  20. Ultrasmall Nanoplatforms as Calcium-Responsive Contrast Agents for Magnetic Resonance Imaging.

    PubMed

    Moussaron, Albert; Vibhute, Sandip; Bianchi, Andrea; Gündüz, Serhat; Kotb, Shady; Sancey, Lucie; Motto-Ros, Vincent; Rizzitelli, Silvia; Crémillieux, Yannick; Lux, Francois; Logothetis, Nikos K; Tillement, Olivier; Angelovski, Goran

    2015-10-01

    The preparation of ultrasmall and rigid platforms (USRPs) that are covalently coupled to macrocycle-based, calcium-responsive/smart contrast agents (SCAs), and the initial in vitro and in vivo validation of the resulting nanosized probes (SCA-USRPs) by means of magnetic resonance imaging (MRI) is reported. The synthetic procedure is robust, allowing preparation of the SCA-USRPs on a multigram scale. The resulting platforms display the desired MRI activity—i.e., longitudinal relaxivity increases almost twice at 7 T magnetic field strength upon saturation with Ca(2+). Cell viability is probed with the MTT assay using HEK-293 cells, which show good tolerance for lower contrast agent concentrations over longer periods of time. On intravenous administration of SCA-USRPs in living mice, MRI studies indicate their rapid accumulation in the renal pelvis and parenchyma. Importantly, the MRI signal increases in both kidney compartments when CaCl2 is also administrated. Laser-induced breakdown spectroscopy experiments confirm accumulation of SCA-USRPs in the renal cortex. To the best of our knowledge, these are the first studies which demonstrate calcium-sensitive MRI signal changes in vivo. Continuing contrast agent and MRI protocol optimizations should lead to wider application of these responsive probes and development of superior functional methods for monitoring calcium-dependent physiological and pathological processes in a dynamic manner. PMID:26179212

  1. Effects of Ultrasmall Orifices on the Electro-generation of Femtoliter-Volume Aqueous Droplets

    PubMed Central

    He, Mingyan; Kuo, Jason S.; Chiu, Daniel T.

    2008-01-01

    The ability to generate individual picoliter- and femtoliter-volume aqueous droplets on-demand is useful for encapsulating and chemically manipulating discrete chemical and biological samples. This paper characterizes the effects of orifice dimensions and material choices on generating such droplets in an immiscible oil phase using single high-voltage pulses with various amplitudes and durations. We have examined microfluidic orifices as small as 1.7 μm in equivalent radii, and found that the electrohydrodynamic jet lengths and the subsequent formation of droplets are affected by the axial aspect ratios of the orifices (length of an orifice divided by its equivalent radius). As higher voltages were used to compensate for the increased capillary pressure and hydrodynamic resistance in ultrasmall orifices, we observed secondary jet protrusions and droplet formations that were not of classical electrohydrodynamic origin. The droplets generated from secondary jets traveled at relatively lower velocities as compared to those of electrohydrodynamic origin, and these slow individual droplets are potentially more useful for applications in microscale chemical reactions. PMID:16800707

  2. Ultrasmall Nanoplatforms as Calcium-Responsive Contrast Agents for Magnetic Resonance Imaging.

    PubMed

    Moussaron, Albert; Vibhute, Sandip; Bianchi, Andrea; Gündüz, Serhat; Kotb, Shady; Sancey, Lucie; Motto-Ros, Vincent; Rizzitelli, Silvia; Crémillieux, Yannick; Lux, Francois; Logothetis, Nikos K; Tillement, Olivier; Angelovski, Goran

    2015-10-01

    The preparation of ultrasmall and rigid platforms (USRPs) that are covalently coupled to macrocycle-based, calcium-responsive/smart contrast agents (SCAs), and the initial in vitro and in vivo validation of the resulting nanosized probes (SCA-USRPs) by means of magnetic resonance imaging (MRI) is reported. The synthetic procedure is robust, allowing preparation of the SCA-USRPs on a multigram scale. The resulting platforms display the desired MRI activity—i.e., longitudinal relaxivity increases almost twice at 7 T magnetic field strength upon saturation with Ca(2+). Cell viability is probed with the MTT assay using HEK-293 cells, which show good tolerance for lower contrast agent concentrations over longer periods of time. On intravenous administration of SCA-USRPs in living mice, MRI studies indicate their rapid accumulation in the renal pelvis and parenchyma. Importantly, the MRI signal increases in both kidney compartments when CaCl2 is also administrated. Laser-induced breakdown spectroscopy experiments confirm accumulation of SCA-USRPs in the renal cortex. To the best of our knowledge, these are the first studies which demonstrate calcium-sensitive MRI signal changes in vivo. Continuing contrast agent and MRI protocol optimizations should lead to wider application of these responsive probes and development of superior functional methods for monitoring calcium-dependent physiological and pathological processes in a dynamic manner.

  3. Poly(cyclohexylethylene)-block-Poly(lactide) Oligomers for Ultrasmall Nanopatterning Using Atomic Layer Deposition.

    PubMed

    Yao, Li; Oquendo, Luis E; Schulze, Morgan W; Lewis, Ronald M; Gladfelter, Wayne L; Hillmyer, Marc A

    2016-03-23

    Poly(cyclohexylethylene)-block-poly(lactide) (PCHE-PLA) block polymers were synthesized through a combination of anionic polymerization, heterogeneous catalytic hydrogenation and controlled ring-opening polymerization. Ordered thin films of PCHE-PLA with ultrasmall hexagonally packed cylinders oriented perpendicularly to the substrate surface were prepared by spin-coating and subsequent solvent vapor annealing for use in two distinct templating strategies. In one approach, selective hydrolytic degradation of the PLA domains generated nanoporous PCHE templates with an average pore diameter of 5 ± 1 nm corroborated by atomic force microscopy and grazing incidence small-angle X-ray scattering. Alternatively, sequential infiltration synthesis (SIS) was employed to deposit Al2O3 selectively into the PLA domains of PCHE-PLA thin films. A combination of argon ion milling and O2 reactive ion etching (RIE) enabled the replication of the Al2O3 nanoarray from the PCHE-PLA template on diverse substrates including silicon and gold with feature diameters less than 10 nm.

  4. High-harmonic ion cyclotron heating and current drive in ultra-small aspect ratio tokamaks

    SciTech Connect

    Batchelor, D.B.; Jaeger, E.F.; Carter, M.D.; Berry, L.A.

    1996-11-01

    Ultra-small aspect ratio tokamaks present a totally new plasma environment for heating and current drive experiments and involve a number of physics issues that have not previously been explored. These devices operate at low magnetic field and relatively high density so that the effective dielectric constant of the plasma to high harmonic fast waves (HHFW), is quite high, and perpendicular wavelength of fast waves is very short. {lambda} {approximately} 2.0 cm compared with {lambda} - 10-20 cm. This makes possible strong electron absorption at high harmonics of the ion cyclotron frequency, {Omega}{sub i}, and at fairly high phase velocity in relation to electron thermal velocity. If the antenna system can control the parallel wave spectrum, this offers the promise of high efficiency off-axis current drive and the possibility for current drive radial profile control. Antenna phasing is ineffective for profile control in conventional tokamaks because of central absorption. There are also challenges for antenna design in this regime because of the high dielectric constant and the large angle of the magnetic field with respect to the equatorial plane ({approximately}45{degrees}), which varies greatly during current ramp. Preliminary experiments in this HHFW regime are being carried out in CDX-U.

  5. Nanoscale Mapping of Dielectric Properties of Nanomaterials from Kilohertz to Megahertz Using Ultrasmall Cantilevers.

    PubMed

    Cadena, Maria J; Sung, Seung Hyun; Boudouris, Bryan W; Reifenberger, Ronald; Raman, Arvind

    2016-04-26

    Electrostatic force microscopy (EFM) is often used for nanoscale dielectric spectroscopy, the measurement of local dielectric properties of materials as a function of frequency. However, the frequency range of atomic force microscopy (AFM)-based dielectric spectroscopy has been limited to a few kilohertz by the resonance frequency and noise of soft microcantilevers used for this purpose. Here, we boost the frequency range of local dielectric spectroscopy by 3 orders of magnitude from a few kilohertz to a few megahertz by developing a technique that exploits the high resonance frequency and low thermal noise of ultrasmall cantilevers (USCs). We map the frequency response of the real and imaginary components of the capacitance gradient (∂C(ω)/∂z) by using second-harmonic EFM and a theoretical model, which relates cantilever dynamics to the complex dielectric constant. We demonstrate the method by mapping the nanoscale dielectric spectrum of polymer-based materials for organic electronic devices. Beyond offering a powerful extension to AFM-based dielectric spectroscopy, the approach also allows the identification of electrostatic excitation frequencies which affords high dielectric contrast on nanomaterials.

  6. Poly(cyclohexylethylene)-block-Poly(lactide) Oligomers for Ultrasmall Nanopatterning Using Atomic Layer Deposition.

    PubMed

    Yao, Li; Oquendo, Luis E; Schulze, Morgan W; Lewis, Ronald M; Gladfelter, Wayne L; Hillmyer, Marc A

    2016-03-23

    Poly(cyclohexylethylene)-block-poly(lactide) (PCHE-PLA) block polymers were synthesized through a combination of anionic polymerization, heterogeneous catalytic hydrogenation and controlled ring-opening polymerization. Ordered thin films of PCHE-PLA with ultrasmall hexagonally packed cylinders oriented perpendicularly to the substrate surface were prepared by spin-coating and subsequent solvent vapor annealing for use in two distinct templating strategies. In one approach, selective hydrolytic degradation of the PLA domains generated nanoporous PCHE templates with an average pore diameter of 5 ± 1 nm corroborated by atomic force microscopy and grazing incidence small-angle X-ray scattering. Alternatively, sequential infiltration synthesis (SIS) was employed to deposit Al2O3 selectively into the PLA domains of PCHE-PLA thin films. A combination of argon ion milling and O2 reactive ion etching (RIE) enabled the replication of the Al2O3 nanoarray from the PCHE-PLA template on diverse substrates including silicon and gold with feature diameters less than 10 nm. PMID:26954771

  7. Catalytic activities of ultra-small β-FeOOH nanorods in ozonation of 4-chlorophenol.

    PubMed

    Oputu, Ogheneochuko; Chowdhury, Mahabubur; Nyamayaro, Kudzanai; Fatoki, Olalekan; Fester, Veruscha

    2015-09-01

    We report the catalytic properties of ultra-small β-FeOOH nanorods in ozonation of 4-chlorophenol (4-CP). XRD, TEM, EDS, SAED, FTIR and BET were used to characterize the prepared material. Interaction between O3 and β-FeOOH was evident from the FTIR spectra. The removal efficiency of 4-CP was significantly enhanced in the presence of β-FeOOH compared to ozone alone. Removal efficiency of 99% and 67% was achieved after 40min in the presence of combined ozone and catalyst and ozone only, respectively. Increasing catalyst load increased COD removal efficiency. Maximum COD removal of 97% was achieved using a catalyst load of 0.1g/100mL of 4-CP solution. Initial 4-CP concentration was not found to be rate limiting below 2×10(-3)mol/L. The catalytic properties of the material during ozonation process were found to be pronounced at lower initial pH of 3.5. Two stage first order kinetics was applied to describe the kinetic behavior of the nanorods at low pH. The first stage of catalytic ozonation was attributed to the heterogeneous surface breakdown of O3 by β-FeOOH, while the second stage was attributed to homogeneous catalysis initiated by reductive dissolution of β-FeOOH at low pH. PMID:26354696

  8. Shrinking of the Cooper Pair Insulator Phase in Thin Films with Ultrasmall Superconducting Islands

    NASA Astrophysics Data System (ADS)

    Joy, J. C.; Zhang, X.; Zhao, C.; Valles, J. M., Jr.; Fernandes, G.; Xu, J. M.

    The ubiquity of the bosonic Cooper Pair Insulator (CPI) phase near the two-dimensional superconductor to insulator transition (SIT) is a long standing question. While a number of two dimensional materials exhibit bosonic insulating phases similar to the Mott Insulator in arrays of ultrasmall, Josephson coupled superconducting islands, others show behaviors consistent with a fermionic insulating phase. Utilizing specially prepared anodized aluminum oxide substrates, we are able to fabricate films reminiscent of arrays of superconducting islands whose properties are tunable by varying the substrate morphology. Our recent work has focused on arrays of islands which possess an energy level spacing comparable to the mean field superconducting gap, where one expects pair breaking followed by fermionic Anderson Localization as the dominant mechanism by which superconductivity is destroyed. Early results show that the paradigmatic bosonic insulator exists only very near the disorder tuned SIT, while films only marginally deeper in the insulating phase exhibit transport distinct from the CPI's reentrant, activated transport. We are grateful for the support of NSF Grant No. DMR-1307290, the AFOSR, and the AOARD. Currently at Northwestern Polytechnical University, Xian, China.

  9. High-Throughput Fabrication of Resonant Metamaterials with Ultrasmall Coaxial Apertures via Atomic Layer Lithography

    PubMed Central

    2016-01-01

    We combine atomic layer lithography and glancing-angle ion polishing to create wafer-scale metamaterials composed of dense arrays of ultrasmall coaxial nanocavities in gold films. This new fabrication scheme makes it possible to shrink the diameter and increase the packing density of 2 nm-gap coaxial resonators, an extreme subwavelength structure first manufactured via atomic layer lithography, both by a factor of 100 with respect to previous studies. We demonstrate that the nonpropagating zeroth-order Fabry-Pérot mode, which possesses slow light-like properties at the cutoff resonance, traps infrared light inside 2 nm gaps (gap volume ∼ λ3/106). Notably, the annular gaps cover only 3% or less of the metal surface, while open-area normalized transmission is as high as 1700% at the epsilon-near-zero (ENZ) condition. The resulting energy accumulation alongside extraordinary optical transmission can benefit applications in nonlinear optics, optical trapping, and surface-enhanced spectroscopies. Furthermore, because the resonance wavelength is independent of the cavity length and dramatically red shifts as the gap size is reduced, large-area arrays can be constructed with λresonance ≫ period, making this fabrication method ideal for manufacturing resonant metamaterials. PMID:26910363

  10. Ultra-small plutonium oxide nanocrystals: an innovative material in plutonium science.

    PubMed

    Hudry, Damien; Apostolidis, Christos; Walter, Olaf; Janssen, Arne; Manara, Dario; Griveau, Jean-Christophe; Colineau, Eric; Vitova, Tonya; Prüssmann, Tim; Wang, Di; Kübel, Christian; Meyer, Daniel

    2014-08-11

    Apart from its technological importance, plutonium (Pu) is also one of the most intriguing elements because of its non-conventional physical properties and fascinating chemistry. Those fundamental aspects are particularly interesting when dealing with the challenging study of plutonium-based nanomaterials. Here we show that ultra-small (3.2±0.9 nm) and highly crystalline plutonium oxide (PuO2 ) nanocrystals (NCs) can be synthesized by the thermal decomposition of plutonyl nitrate ([PuO2 (NO3 )2 ]⋅3 H2 O) in a highly coordinating organic medium. This is the first example reporting on the preparation of significant quantities (several tens of milligrams) of PuO2 NCs, in a controllable and reproducible manner. The structure and magnetic properties of PuO2 NCs have been characterized by a wide variety of techniques (powder X-ray diffraction (PXRD), X-ray absorption fine structure (XAFS), X-ray absorption near edge structure (XANES), TEM, IR, Raman, UV/Vis spectroscopies, and superconducting quantum interference device (SQUID) magnetometry). The current PuO2 NCs constitute an innovative material for the study of challenging problems as diverse as the transport behavior of plutonium in the environment or size and shape effects on the physics of transuranium elements.

  11. High-Throughput Fabrication of Resonant Metamaterials with Ultrasmall Coaxial Apertures via Atomic Layer Lithography.

    PubMed

    Yoo, Daehan; Nguyen, Ngoc-Cuong; Martin-Moreno, Luis; Mohr, Daniel A; Carretero-Palacios, Sol; Shaver, Jonah; Peraire, Jaime; Ebbesen, Thomas W; Oh, Sang-Hyun

    2016-03-01

    We combine atomic layer lithography and glancing-angle ion polishing to create wafer-scale metamaterials composed of dense arrays of ultrasmall coaxial nanocavities in gold films. This new fabrication scheme makes it possible to shrink the diameter and increase the packing density of 2 nm-gap coaxial resonators, an extreme subwavelength structure first manufactured via atomic layer lithography, both by a factor of 100 with respect to previous studies. We demonstrate that the nonpropagating zeroth-order Fabry-Pérot mode, which possesses slow light-like properties at the cutoff resonance, traps infrared light inside 2 nm gaps (gap volume ∼ λ(3)/10(6)). Notably, the annular gaps cover only 3% or less of the metal surface, while open-area normalized transmission is as high as 1700% at the epsilon-near-zero (ENZ) condition. The resulting energy accumulation alongside extraordinary optical transmission can benefit applications in nonlinear optics, optical trapping, and surface-enhanced spectroscopies. Furthermore, because the resonance wavelength is independent of the cavity length and dramatically red shifts as the gap size is reduced, large-area arrays can be constructed with λresonance ≫ period, making this fabrication method ideal for manufacturing resonant metamaterials.

  12. Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe3O4 nanoparticle rings

    PubMed Central

    Takeno, Yumu; Murakami, Yasukazu; Sato, Takeshi; Tanigaki, Toshiaki; Park, Hyun Soon; Shindo, Daisuke; Ferguson, R. Matthew

    2014-01-01

    This study reports on the correlation between crystal orientation and magnetic flux distribution of Fe3O4 nanoparticles in the form of self-assembled rings. High-resolution transmission electron microscopy demonstrated that the nanoparticles were single-crystalline, highly monodispersed, (25 nm average diameter), and showed no appreciable lattice imperfections such as twins or stacking faults. Electron holography studies of these superparamagnetic nanoparticle rings indicated significant fluctuations in the magnetic flux lines, consistent with variations in the magnetocrystalline anisotropy of the nanoparticles. The observations provide useful information for a deeper understanding of the micromagnetics of ultrasmall nanoparticles, where the magnetic dipolar interaction competes with the magnetic anisotropy. PMID:25422526

  13. Unexpected magnetization in highly pure metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Hanna, C. B.; Alanko, Gordon; Beausoleil, Boone; Chess, Jordan; Thurber, Aaron; Punnoose, Alex

    2012-02-01

    We report the synthesis and characterization of a large set of highly pure metal oxide (CeO2, SnO2 and ZnO) nanoparticles of ultra-small size (2-10 nm). While the metal oxide systems in this study are non-magnetic as bulk materials, our prepared nanoparticles possess an unexpected small room-temperature ferromagnetic magnetization on the order of 0.001 emu/g. This magnetization is shown to not be a result of magnetic impurities, and is discussed in terms of modification of the electronic structure and crystal lattice. These nanoparticles were thoroughly characterized in their size and phase by x-ray diffraction, morphology by transmission electron microscopy, chemical state and elemental purity by x-ray photoelectron spectroscopy, electronic bandgap by UV-vis absorption spectroscopy, and magnetic properties by vibrating sample magnetometry and electron paramagnetic resonance.

  14. Mixed lanthanide oxide nanoparticles as dual imaging agent in biomedicine

    NASA Astrophysics Data System (ADS)

    Xu, Wenlong; Bony, Badrul Alam; Kim, Cho Rong; Baeck, Jong Su; Chang, Yongmin; Bae, Ji Eun; Chae, Kwon Seok; Kim, Tae Jeong; Lee, Gang Ho

    2013-11-01

    There is no doubt that the molecular imaging is an extremely important technique in diagnosing diseases. Dual imaging is emerging as a step forward in molecular imaging technique because it can provide us with more information useful for diagnosing diseases than single imaging. Therefore, diverse dual imaging modalities should be developed. Molecular imaging generally relies on imaging agents. Mixed lanthanide oxide nanoparticles could be valuable materials for dual magnetic resonance imaging (MRI)-fluorescent imaging (FI) because they have both excellent and diverse magnetic and fluorescent properties useful for dual MRI-FI, depending on lanthanide ions used. Since they are mixed nanoparticles, they are compact, robust, and stable, which is extremely useful for biomedical applications. They can be also easily synthesized with facile composition control. In this study, we explored three systems of ultrasmall mixed lanthanide (Dy/Eu, Ho/Eu, and Ho/Tb) oxide nanoparticles to demonstrate their usefulness as dual T2 MRI-FI agents.

  15. Homologous RBC-derived vesicles as ultrasmall carriers of iron oxide for magnetic resonance imaging of stem cells

    NASA Astrophysics Data System (ADS)

    Chang, Microsugar; Hsiao, Jong-Kai; Yao, Ming; Chien, Li-Ying; Hsu, Szu-Chun; Ko, Bor-Sheng; Chen, Shin-Tai; Liu, Hon-Man; Chen, Yao-Chang; Yang, Chung-Shi; Huang, Dong-Ming

    2010-06-01

    Ultrasmall superparamagnetic iron oxide (USPIO) particles are very useful for cellular magnetic resonance imaging (MRI), which plays a key role in developing successful stem cell therapies. However, their low intracellular labeling efficiency, and biosafety concerns associated with their use, have limited their potential usage. In this study we develop a novel system composed of RBC-derived vesicles (RDVs) for efficient delivery of USPIO particles into human bone marrow mesenchymal stem cells (MSCs) for cellular MRI in vitro and in vivo. RDVs are highly biosafe to their autologous MSCs as manifested by cell viability, differentiation, and gene microarray assays. The data demonstrate the potential of RDVs as intracellular delivery vehicles for biomedical applications.

  16. Ultrasmall Gold Nanorod Vesicles with Enhanced Tumor Accumulation and Fast Excretion from the Body for Cancer Therapy.

    PubMed

    Song, Jibin; Yang, Xiangyu; Jacobson, Orit; Huang, Peng; Sun, Xiaolian; Lin, Lisen; Yan, Xuefeng; Niu, Gang; Ma, Qingjie; Chen, Xiaoyuan

    2015-09-01

    A new kind of ultrasmall dissociable AuNR@PEG/PLGA vesicles (≈60 nm) (AuNR = gold nanorod; PEG = poly(ethylene glycol); PLGA = poly(lactic-co-glycolic acid)) assembled from small AuNRs (dimension: ≈8 nm × 2 nm) is reported. They exhibit several striking features: prolonged circulation and prominent tumor accumulation; rapid excretion from the body as AuNR@PEG after therapy; enhanced photoacoustic and photo thermal properties; and high photothermal cancer therapy efficacy. PMID:26198622

  17. Quantum 1/f noise in high technology applications including ultrasmall structures and devices

    NASA Astrophysics Data System (ADS)

    Handel, Peter H.

    1994-05-01

    The present report brings a final answer to the question on the nature of fundamental 1/f noise and its ubiquity. A sufficient criterion for a 1/f spectrum in arbitrary chaotic nonlinear systems is derived for the first time. This criterion guarantees a 1/f spectrum for nonlinear systems which also satisfy a condition of mathematical homogeneity. Briefly stated, nonlinearity + homogeneity = 1/f noise. The criterion results because the 1/f spectrum reproduces itself in a self-convolution. Among the five examples to which the criterion is applied is also quantum electrodynamics (QED), resulting in quantum 1/f noise as a fundamental form of quantum chaos. Nonlinearity of the system of a charged particle and its field, plus the basic homogeneity of physical equations causes the criterion to predict the quantum 1/f effect. The simple universal quantum 1/f formula is applied to infrared detectors and yields quantum 1/f noise in the dark current, but not in the photogenerated current. The fractal dimension of quantum 1/f noise is determined on the basis of its quantum chaos definition and is obtained theoretically as a function of bandwidth in a simple model by applying the Grassberger-Procaccia-Takens algorithm to the quantum 1/f theory. The quantum 1/f effect is successfully applied to quartz resonators and bipolar junction transistors. Finally, the quantum 1/f mobility fluctuations are calculated in silicon and the coherent quantum 1/f effect is derived for the first time from a new QED propagator with branch-point singularity. This opens the way to better bridging the gap between coherent and conventional quantum 1/f noise in small and ultrasmall devices.

  18. A self-sensing piezoelectric microcantilever biosensor for detection of ultrasmall adsorbed masses: theory and experiments.

    PubMed

    Faegh, Samira; Jalili, Nader; Sridhar, Srinivas

    2013-05-10

    Detection of ultrasmall masses such as proteins and pathogens has been made possible as a result of advancements in nanotechnology. Development of label-free and highly sensitive biosensors has enabled the transduction of molecular recognition into detectable physical quantities. Microcantilever (MC)-based systems have played a widespread role in developing such biosensors. One of the most important drawbacks of all of the available biosensors is that they all come at a very high cost. Moreover, there are certain limitations in the measurement equipments attached to the biosensors which are mostly optical measurement systems. A unique self-sensing detection technique is proposed in this paper in order to address most of the limitations of the current measurement systems. A self-sensing bridge is used to excite piezoelectric MC-based sensor functioning in dynamic mode, which simultaneously measures the system's response through the self-induced voltage generated in the piezoelectric material. As a result, the need for bulky, expensive read-out equipment is eliminated. A comprehensive mathematical model is presented for the proposed self-sensing detection platform using distributed-parameters system modeling. An adaptation strategy is then implemented in the second part in order to compensate for the time-variation of piezoelectric properties which dynamically improves the behavior of the system. Finally, results are reported from an extensive experimental investigation carried out to prove the capability of the proposed platform. Experimental results verified the proposed mathematical modeling presented in the first part of the study with accuracy of 97.48%. Implementing the adaptation strategy increased the accuracy to 99.82%. These results proved the measurement capability of the proposed self-sensing strategy. It enables development of a cost-effective, sensitive and miniaturized mass sensing platform.

  19. A novel and facile synthesis of porous SiO2-coated ultrasmall Se particles as a drug delivery nanoplatform for efficient synergistic treatment of cancer cells

    NASA Astrophysics Data System (ADS)

    Liu, Xijian; Deng, Guoying; Wang, Yeying; Wang, Qian; Gao, Zhifang; Sun, Yangang; Zhang, Wenlong; Lu, Jie; Hu, Junqing

    2016-04-01

    A novel and facile synthetic route has been developed to fabricate porous SiO2-coated ultrasmall Se particles (Se@SiO2 nanospheres) as a drug delivery nanoplatform which combines Se quantum dots and doxorubicin (DOX) for efficient synergistic treatment of cancer cells.A novel and facile synthetic route has been developed to fabricate porous SiO2-coated ultrasmall Se particles (Se@SiO2 nanospheres) as a drug delivery nanoplatform which combines Se quantum dots and doxorubicin (DOX) for efficient synergistic treatment of cancer cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02298g

  20. How size evaluation of lymph node is protocol dependent in MRI when using ultrasmall superparamagnetic iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Gharehaghaji, Nahideh; Oghabian, Mohammad Ali; Sarkar, Saeed; Darki, Fahimeh; Beitollahi, Ali

    2009-05-01

    In this study, the volume of susceptibility artifact was evaluated in T1 and T2-weighted spin echo (SE) and gradient echo (GRE) images at various parameters using registration and subtraction methods. In order to state an important misinterpretation problem in lymphography, it was demonstrated that a lymph node size may be enlarged approximately 10 times when a T2*-weighted GRE protocol is used. To overcome this problem a technical consideration using multisequence (GRE and SE) paradigm was suggested to ensure both lymph node detection and metastasis identification in lymphatic system. The paradigm was also extended by post-processing manipulation of the SE images using a registration and subtraction approach for detection of lymphatic lesions.

  1. Imaging of activated complement using ultrasmall superparamagnetic iron oxide particles (USPIO) - conjugated vectors: an in vivo in utero non-invasive method to predict placental insufficiency and abnormal fetal brain development

    PubMed Central

    Girardi, G; Fraser, J; Lennen, R; Vontell, R; Jansen, M; Hutchison, G

    2015-01-01

    In the current study, we have developed a magnetic resonance imaging-based method for non-invasive detection of complement activation in placenta and foetal brain in vivo in utero. Using this method, we found that anti-complement C3-targeted ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles bind within the inflamed placenta and foetal brain cortical tissue, causing a shortening of the T2* relaxation time. We used two mouse models of pregnancy complications: a mouse model of obstetrics antiphospholipid syndrome (APS) and a mouse model of preterm birth (PTB). We found that detection of C3 deposition in the placenta in the APS model was associated with placental insufficiency characterised by increased oxidative stress, decreased vascular endothelial growth factor and placental growth factor levels and intrauterine growth restriction. We also found that foetal brain C3 deposition was associated with cortical axonal cytoarchitecture disruption and increased neurodegeneration in the mouse model of APS and in the PTB model. In the APS model, foetuses that showed increased C3 in their brains additionally expressed anxiety-related behaviour after birth. Importantly, USPIO did not affect pregnancy outcomes and liver function in the mother and the offspring, suggesting that this method may be useful for detecting complement activation in vivo in utero and predicting placental insufficiency and abnormal foetal neurodevelopment that leads to neuropsychiatric disorders. PMID:25245499

  2. Complete Exchange of the Hydrophobic Dispersant Shell on Monodisperse Superparamagnetic Iron Oxide Nanoparticles.

    PubMed

    Bixner, Oliver; Lassenberger, Andrea; Baurecht, Dieter; Reimhult, Erik

    2015-08-25

    High-temperature synthesized monodisperse superparamagnetic iron oxide nanoparticles are obtained with a strongly bound ligand shell of oleic acid and its decomposition products. Most applications require a stable presentation of a defined surface chemistry; therefore, the native shell has to be completely exchanged for dispersants with irreversible affinity to the nanoparticle surface. We evaluate by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) the limitations of commonly used approaches. A mechanism and multiple exchange scheme that attains the goal of complete and irreversible ligand replacement on monodisperse nanoparticles of various sizes is presented. The obtained hydrophobic nanoparticles are ideally suited for magnetically controlled drug delivery and membrane applications and for the investigation of fundamental interfacial properties of ultrasmall core-shell architectures. PMID:26226071

  3. Complete Exchange of the Hydrophobic Dispersant Shell on Monodisperse Superparamagnetic Iron Oxide Nanoparticles

    PubMed Central

    2015-01-01

    High-temperature synthesized monodisperse superparamagnetic iron oxide nanoparticles are obtained with a strongly bound ligand shell of oleic acid and its decomposition products. Most applications require a stable presentation of a defined surface chemistry; therefore, the native shell has to be completely exchanged for dispersants with irreversible affinity to the nanoparticle surface. We evaluate by attenuated total reflectance−Fourier transform infrared spectroscopy (ATR−FTIR) and thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) the limitations of commonly used approaches. A mechanism and multiple exchange scheme that attains the goal of complete and irreversible ligand replacement on monodisperse nanoparticles of various sizes is presented. The obtained hydrophobic nanoparticles are ideally suited for magnetically controlled drug delivery and membrane applications and for the investigation of fundamental interfacial properties of ultrasmall core–shell architectures. PMID:26226071

  4. Wedge hybrid plasmonic THz waveguide with long propagation length and ultra-small deep-subwavelength mode area

    PubMed Central

    Gui, Chengcheng; Wang, Jian

    2015-01-01

    We present a novel design of wedge hybrid plasmonic terahertz (THz) waveguide consisting of a silicon (Si) nanowire cylinder above a triangular gold wedge with surrounded high-density polyethylene as cladding. It features long propagation length and ultra-small deep-subwavelength mode confinement. The mode properties of wedge hybrid plasmonic THz waveguide are comprehensively characterized in terms of propagation length (L), normalized mode area (Aeff /A0), figure of merit (FoM), and chromatic dispersion (D). The designed wedge hybrid plasmonic THz waveguide enables an ultra-small deep-subwavelength mode area which is more than one-order of magnitude smaller compared to previous rectangular one. When choosing the diameter of Si nanowire cylinder, a smaller diameter (e.g. 10 μm) is preferred to achieve longer L and higher FoM, while a larger diameter (e.g. 60 μm) is favorable to obtain smaller Aeff /A0 and higher FoM. We further study the impacts of possible practical fabrication errors on the mode properties. The simulated results of propagation length and normalized mode area show that the proposed wedge hybrid plasmonic THz waveguide is tolerant to practical fabrication errors in geometry parameters such as misalignment in the horizontal direction, variation of wedge tip angle, and variation of wedge tip curvature radius. PMID:26155782

  5. Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe{sub 3}O{sub 4} nanoparticle rings

    SciTech Connect

    Takeno, Yumu; Murakami, Yasukazu E-mail: kannanmk@uw.edu; Shindo, Daisuke; Sato, Takeshi; Tanigaki, Toshiaki; Park, Hyun Soon; Ferguson, R. Matthew; Krishnan, Kannan M. E-mail: kannanmk@uw.edu

    2014-11-03

    This study reports on the correlation between crystal orientation and magnetic flux distribution of Fe{sub 3}O{sub 4} nanoparticles in the form of self-assembled rings. High-resolution transmission electron microscopy demonstrated that the nanoparticles were single-crystalline, highly monodispersed, (25 nm average diameter), and showed no appreciable lattice imperfections such as twins or stacking faults. Electron holography studies of these superparamagnetic nanoparticle rings indicated significant fluctuations in the magnetic flux lines, consistent with variations in the magnetocrystalline anisotropy of the nanoparticles. The observations provide useful information for a deeper understanding of the micromagnetics of ultrasmall nanoparticles, where the magnetic dipolar interaction competes with the magnetic anisotropy.

  6. Manganese (II) Chelate Functionalized Copper Sulfide Nanoparticles for Efficient Magnetic Resonance/Photoacoustic Dual-Modal Imaging Guided Photothermal Therapy.

    PubMed

    Liu, Renfa; Jing, Lijia; Peng, Dong; Li, Yong; Tian, Jie; Dai, Zhifei

    2015-01-01

    The integration of diagnostic and therapeutic functionalities into one nanoplatform shows great promise in cancer therapy. In this research, manganese (II) chelate functionalized copper sulfide nanoparticles were successfully prepared using a facile hydrothermal method. The obtained ultrasmall nanoparticles exhibit excellent photothermal effect and photoaoustic activity. Besides, the high loading content of Mn(II) chelates makes the nanoparticles attractive T1 contrast agent in magnetic resonance imaging (MRI). In vivo photoacoustic imaging (PAI) results showed that the nanoparticles could be efficiently accumulated in tumor site in 24 h after systematic administration, which was further validated by MRI tests. The subsequent photothermal therapy of cancer in vivo was achieved without inducing any observed side effects. Therefore, the copper sulfide nanoparticles functionalized with Mn(II) chelate hold great promise as a theranostic nanomedicine for MR/PA dual-modal imaging guided photothermal therapy of cancer.

  7. Manganese (II) Chelate Functionalized Copper Sulfide Nanoparticles for Efficient Magnetic Resonance/Photoacoustic Dual-Modal Imaging Guided Photothermal Therapy

    PubMed Central

    Liu, Renfa; Jing, Lijia; Peng, Dong; Li, Yong; Tian, Jie; Dai, Zhifei

    2015-01-01

    The integration of diagnostic and therapeutic functionalities into one nanoplatform shows great promise in cancer therapy. In this research, manganese (II) chelate functionalized copper sulfide nanoparticles were successfully prepared using a facile hydrothermal method. The obtained ultrasmall nanoparticles exhibit excellent photothermal effect and photoaoustic activity. Besides, the high loading content of Mn(II) chelates makes the nanoparticles attractive T1 contrast agent in magnetic resonance imaging (MRI). In vivo photoacoustic imaging (PAI) results showed that the nanoparticles could be efficiently accumulated in tumor site in 24 h after systematic administration, which was further validated by MRI tests. The subsequent photothermal therapy of cancer in vivo was achieved without inducing any observed side effects. Therefore, the copper sulfide nanoparticles functionalized with Mn(II) chelate hold great promise as a theranostic nanomedicine for MR/PA dual-modal imaging guided photothermal therapy of cancer. PMID:26284144

  8. Molecular magnetic resonance imaging of activated hepatic stellate cells with ultrasmall superparamagnetic iron oxide targeting integrin αvβ3 for staging liver fibrosis in rat model

    PubMed Central

    Zhang, Caiyuan; Liu, Huanhuan; Cui, Yanfen; Li, Xiaoming; Zhang, Zhongyang; Zhang, Yong; Wang, Dengbin

    2016-01-01

    Purpose To evaluate the expression level of integrin αvβ3 on activated hepatic stellate cells (HSCs) at different stages of liver fibrosis induced by carbon tetrachloride (CCl4) in rat model and the feasibility to stage liver fibrosis by using molecular magnetic resonance imaging (MRI) with arginine-glycine-aspartic acid (RGD) peptide modified ultrasmall superparamagnetic iron oxide nanoparticle (USPIO) specifically targeting integrin αvβ3. Materials and methods All experiments received approval from our Institutional Animal Care and Use Committee. Thirty-six rats were randomly divided into three groups of 12 subjects each, and intraperitoneally injected with CCl4 for either 3, 6, or 9 weeks. Controls (n=10) received pure olive oil. The change in T2* relaxation rate (ΔR2*) pre- and postintravenous administration of RGD-USPIO or naked USPIO was measured by 3.0T clinical MRI and compared by one-way analysis of variance or the Student’s t-test. The relationship between expression level of integrin αvβ3 and liver fibrotic degree was evaluated by Spearman’s ranked correlation. Results Activated HSCs were confirmed to be the main cell types expressing integrin αvβ3 during liver fibrogenesis. The protein level of integrin αv and β3 subunit expressed on activated HSCs was upregulated and correlated well with the progression of liver fibrosis (r=0.954, P<0.001; r=0.931, P<0.001, respectively). After injection of RGD-USPIO, there is significant difference in ΔR2* among rats treated with 0, 3, 6, and 9 weeks of CCl4 (P<0.001). The accumulation of iron particles in fibrotic liver specimen is significantly greater for RGD-USPIO than naked USPIO after being injected with equal dose of iron. Conclusion Molecular MRI of integrin αvβ3 expressed on activated HSCs by using RGD-USPIO may distinguish different liver fibrotic stages in CCl4 rat model and shows promising to noninvasively monitor the progression of the liver fibrosis and therapeutic response to

  9. A new approach to quantification of metamorphism using ultra-small and small angle neutron scattering.

    SciTech Connect

    Anovitz, Lawrence {Larry} M; Lynn, Gary W; Cole, David R

    2009-12-01

    In this paper we report the results of a study using small angle and ultra-small angle neutron scattering techniques (SANS and USANS) to examine the evolution of carbonates during contact metamorphism. Data were obtained from samples collected along two transects in the metamorphosed Hueco limestone at the Marble Canyon, Texas, contact aureole. These samples were collected from the igneous contact out to {approx}1700 m. Scattering curves obtained from these samples show mass fractal behavior at low scattering vectors, and surface fractal behavior at high scattering vectors. Significant changes are observed in the surface and mass fractal dimensions as well as the correlation lengths (pore and grain sizes), surface area to volume ratio and surface Gibbs Free energy as a function of distance, including regions of the aureole outside the range of classic metamorphic petrology. A change from mass-fractal to non-fractal behavior is observed at larger scales near the outer boundary of the aureole that implies significant reorganization of pore distributions early in the metamorphic history. Surface fractal results suggest significant smoothing of grain boundaries, coupled with changes in pore sizes. A section of the scattering curve with a slope less than -4 appears at low-Q in metamorphosed samples, which is not present in unmetamorphosed samples. A strong spike in the surface area to volume ratio is observed in rocks near the mapped metamorphic limit, which is associated with reaction of small amounts of organic material to graphite. It may also represent an increase in pore volume or permeability, suggesting that a high permeability zone forms at the boundary of the aureole and moves outwards as metamorphism progresses. Neutron scattering data also correlate well with transmission electron microscopic (TEM) observations, which show formation of micro- and nanopores and microfractures during metamorphism. The scattering data are, however, quantifiable for a bulk rock

  10. A new approach to quantification of metamorphism using ultra-small and small angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Anovitz, Lawrence M.; Lynn, Gary W.; Cole, David R.; Rother, Gernot; Allard, Lawrence F.; Hamilton, William A.; Porcar, Lionel; Kim, Man-Ho

    2009-12-01

    In this paper we report the results of a study using small angle and ultra-small angle neutron scattering techniques (SANS and USANS) to examine the evolution of carbonates during contact metamorphism. Data were obtained from samples collected along two transects in the metamorphosed Hueco limestone at the Marble Canyon, Texas, contact aureole. These samples were collected from the igneous contact out to ˜1700 m. Scattering curves obtained from these samples show mass fractal behavior at low scattering vectors, and surface fractal behavior at high scattering vectors. Significant changes are observed in the surface and mass fractal dimensions as well as the correlation lengths (pore and grain sizes), surface area to volume ratio and surface Gibbs Free energy as a function of distance, including regions of the aureole outside the range of classic metamorphic petrology. A change from mass-fractal to non-fractal behavior is observed at larger scales near the outer boundary of the aureole that implies significant reorganization of pore distributions early in the metamorphic history. Surface fractal results suggest significant smoothing of grain boundaries, coupled with changes in pore sizes. A section of the scattering curve with a slope less than -4 appears at low- Q in metamorphosed samples, which is not present in unmetamorphosed samples. A strong spike in the surface area to volume ratio is observed in rocks near the mapped metamorphic limit, which is associated with reaction of small amounts of organic material to graphite. It may also represent an increase in pore volume or permeability, suggesting that a high permeability zone forms at the boundary of the aureole and moves outwards as metamorphism progresses. Neutron scattering data also correlate well with transmission electron microscopic (TEM) observations, which show formation of micro- and nanopores and microfractures during metamorphism. The scattering data are, however, quantifiable for a bulk rock in a

  11. The role of pH on the particle size and magnetic consequence of cobalt ferrite

    NASA Astrophysics Data System (ADS)

    Safi, Rohollah; Ghasemi, Ali; Shoja-Razavi, Reza; Tavousi, Majid

    2015-12-01

    Cobalt ferrite (CoFe2O4) nanoparticles with various size distributions were prepared by a chemical co-precipitation method at different pH condition from 8 to 13. The structural characterizations of the prepared samples were carried out using powder X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscope. The XRD results revealed that a single cubic CoFe2O4 phase with the average crystallite sizes of about 5-24 nm were formed. Cation distribution occupancy in tetrahedral and octahedral sites were estimated by employing Rietveld refinement technique. The results showed that the whole series of samples contain a partial inverse spinel structure. FTIR measurements between 370 and 4000 cm-1 confirmed the intrinsic cation vibrations of spinel structure of the samples. The room temperature magnetic properties of the samples have been examined using vibrating sample magnetometer. It is found that with increasing the pH of reaction, the magnetization and coercive field could be increased. The sample synthesized at pH~8 and 9 showed superparamagnetic behavior and highest coercive field up to 650 Oe is attributed to the sample synthesized with pH~13.

  12. Synthesis of Water Dispersible and Catalytically Active Gold-Decorated Cobalt Ferrite Nanoparticles.

    PubMed

    Silvestri, Alessandro; Mondini, Sara; Marelli, Marcello; Pifferi, Valentina; Falciola, Luigi; Ponti, Alessandro; Ferretti, Anna Maria; Polito, Laura

    2016-07-19

    Hetero-nanoparticles represent an important family of composite nanomaterials that in the past years are attracting ever-growing interest. Here, we report a new strategy for the synthesis of water dispersible cobalt ferrite nanoparticles (CoxFe3-xO4 NPs) decorated with ultrasmall (2-3 nm) gold nanoparticles (Au NPs). The synthetic procedure is based on the use of 2,3-meso-dimercaptosuccinic acid (DMSA), which plays a double role. First, it transfers cobalt ferrite NPs from the organic phase to aqueous media. Second, the DMSA reductive power promotes the in situ nucleation of gold NPs in proximity of the magnetic NP surface. Following this procedure, we achieved a water dispersible nanosystem (CoxFe3-xO4-DMSA-Au NPs) which combines the cobalt ferrite magnetic properties with the catalytic features of ultrasmall Au NPs. We showed that CoxFe3-xO4-DMSA-Au NPs act as an efficient nanocatalyst to reduce 4-nitrophenol to 4-aminophenol and that they can be magnetically recovered and recycled. It is noteworthy that such nanosystem is more catalytically active than Au NPs with equal size. Finally, a complete structural and chemical characterization of the hetero-NPs is provided.

  13. High-Density Lipoproteins: Nature's Multifunctional Nanoparticles.

    PubMed

    Kuai, Rui; Li, Dan; Chen, Y Eugene; Moon, James J; Schwendeman, Anna

    2016-03-22

    High-density lipoproteins (HDL) are endogenous nanoparticles involved in the transport and metabolism of cholesterol, phospholipids, and triglycerides. HDL is well-known as the "good" cholesterol because it not only removes excess cholesterol from atherosclerotic plaques but also has anti-inflammatory and antioxidative properties, which protect the cardiovascular system. Circulating HDL also transports endogenous proteins, vitamins, hormones, and microRNA to various organs. Compared with other synthetic nanocarriers, such as liposomes, micelles, and inorganic and polymeric nanoparticles, HDL has unique features that allow them to deliver cargo to specific targets more efficiently. These attributes include their ultrasmall size (8-12 nm in diameter), high tolerability in humans (up to 8 g of protein per infusion), long circulating half-life (12-24 h), and intrinsic targeting properties to different recipient cells. Various recombinant ApoA proteins and ApoA mimetic peptides have been recently developed for the preparation of reconstituted HDL that exhibits properties similar to those of endogenous HDL and has a potential for industrial scale-up. In this review, we will summarize (a) clinical pharmacokinetics and safety of reconstituted HDL products, (b) comparison of HDL with inorganic and other organic nanoparticles, PMID:26889958

  14. Cytotoxicity, tumor targeting and PET imaging of sub-5 nm KGdF4 multifunctional rare earth nanoparticles

    NASA Astrophysics Data System (ADS)

    Cao, Xinmin; Cao, Fengwen; Xiong, Liqin; Yang, Yang; Cao, Tianye; Cai, Xi; Hai, Wangxi; Li, Biao; Guo, Yixiao; Zhang, Yimin; Li, Fuyou

    2015-08-01

    Ultrasmall sub-5 nm KGdF4 rare earth nanoparticles were synthesized as multifunctional probes for fluorescent, magnetic, and radionuclide imaging. The cytotoxicity of these nanoparticles in human glioblastoma U87MG and human non-small cell lung carcinoma H1299 cells was evaluated, and their application for in vitro and in vivo tumor targeted imaging has also been demonstrated.Ultrasmall sub-5 nm KGdF4 rare earth nanoparticles were synthesized as multifunctional probes for fluorescent, magnetic, and radionuclide imaging. The cytotoxicity of these nanoparticles in human glioblastoma U87MG and human non-small cell lung carcinoma H1299 cells was evaluated, and their application for in vitro and in vivo tumor targeted imaging has also been demonstrated. Electronic supplementary information (ESI) available: Details of the experimental section as well as EDXA, XRD, zeta potential, FTIR, TGA, stability, TEM, Z scanning, ICP-MS, and MicroPET/CT images. See DOI: 10.1039/c5nr03374h

  15. Bifunctional non-noble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting.

    PubMed

    Wang, Haotian; Lee, Hyun-Wook; Deng, Yong; Lu, Zhiyi; Hsu, Po-Chun; Liu, Yayuan; Lin, Dingchang; Cui, Yi

    2015-01-01

    Developing earth-abundant, active and stable electrocatalysts which operate in the same electrolyte for water splitting, including oxygen evolution reaction and hydrogen evolution reaction, is important for many renewable energy conversion processes. Here we demonstrate the improvement of catalytic activity when transition metal oxide (iron, cobalt, nickel oxides and their mixed oxides) nanoparticles (∼20 nm) are electrochemically transformed into ultra-small diameter (2-5 nm) nanoparticles through lithium-induced conversion reactions. Different from most traditional chemical syntheses, this method maintains excellent electrical interconnection among nanoparticles and results in large surface areas and many catalytically active sites. We demonstrate that lithium-induced ultra-small NiFeOx nanoparticles are active bifunctional catalysts exhibiting high activity and stability for overall water splitting in base. We achieve 10 mA cm(-2) water-splitting current at only 1.51 V for over 200 h without degradation in a two-electrode configuration and 1 M KOH, better than the combination of iridium and platinum as benchmark catalysts. PMID:26099250

  16. Bifunctional non-noble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting

    NASA Astrophysics Data System (ADS)

    Wang, Haotian; Lee, Hyun-Wook; Deng, Yong; Lu, Zhiyi; Hsu, Po-Chun; Liu, Yayuan; Lin, Dingchang; Cui, Yi

    2015-06-01

    Developing earth-abundant, active and stable electrocatalysts which operate in the same electrolyte for water splitting, including oxygen evolution reaction and hydrogen evolution reaction, is important for many renewable energy conversion processes. Here we demonstrate the improvement of catalytic activity when transition metal oxide (iron, cobalt, nickel oxides and their mixed oxides) nanoparticles (~20 nm) are electrochemically transformed into ultra-small diameter (2-5 nm) nanoparticles through lithium-induced conversion reactions. Different from most traditional chemical syntheses, this method maintains excellent electrical interconnection among nanoparticles and results in large surface areas and many catalytically active sites. We demonstrate that lithium-induced ultra-small NiFeOx nanoparticles are active bifunctional catalysts exhibiting high activity and stability for overall water splitting in base. We achieve 10 mA cm-2 water-splitting current at only 1.51 V for over 200 h without degradation in a two-electrode configuration and 1 M KOH, better than the combination of iridium and platinum as benchmark catalysts.

  17. Inorganic nanoparticle-based T1 and T1/T2 magnetic resonance contrast probes

    NASA Astrophysics Data System (ADS)

    Hu, Fengqin; Zhao, Yong Sheng

    2012-09-01

    Magnetic resonance imaging (MRI) yields high spatially resolved contrast with anatomical details for diagnosis, deeper penetration depth and rapid 3D scanning. To improve imaging sensitivity, adding contrast agents accelerates the relaxation rate of water molecules, thereby greatly increasing the contrast between specific issues or organs of interest. Currently, the majority of T1 contrast agents are paramagnetic molecular complexes, typically Gd(iii) chelates. Various nanoparticulate T1 and T1/T2 contrast agents have recently been investigated as novel agents possessing the advantages of both the T1 contrast effect and nanostructural characteristics. In this minireview, we describe the recent progress of these inorganic nanoparticle-based MRI contrast agents. Specifically, we mainly report on Gd and Mn-based inorganic nanoparticles and ultrasmall iron oxide/ferrite nanoparticles.

  18. Glutathione-Coated Luminescent Gold Nanoparticles: A Surface Ligand for Minimizing Serum Protein Adsorption

    PubMed Central

    2015-01-01

    Ultrasmall glutathione-coated luminescent gold nanoparticles (GS-AuNPs) are known for their high resistance to serum protein adsorption. Our studies show that these NPs can serve as surface ligands to significantly enhance the physiological stability and lower the serum protein adsorption of superparamagnetic iron oxide nanoparticles (SPIONs), in addition to rendering the NPs the luminescence property. After the incorporation of GS-AuNPs onto the surface of SPIONs to form the hybrid nanoparticles (HBNPs), these SPIONs’ protein adsorption was about 10-fold lower than those of the pure glutathione-coated SPIONs suggesting that GS-AuNPs are capable of providing a stealth effect against serum proteins. PMID:25029478

  19. Glutathione-coated luminescent gold nanoparticles: a surface ligand for minimizing serum protein adsorption.

    PubMed

    Vinluan, Rodrigo D; Liu, Jinbin; Zhou, Chen; Yu, Mengxiao; Yang, Shengyang; Kumar, Amit; Sun, Shasha; Dean, Andrew; Sun, Xiankai; Zheng, Jie

    2014-08-13

    Ultrasmall glutathione-coated luminescent gold nanoparticles (GS-AuNPs) are known for their high resistance to serum protein adsorption. Our studies show that these NPs can serve as surface ligands to significantly enhance the physiological stability and lower the serum protein adsorption of superparamagnetic iron oxide nanoparticles (SPIONs), in addition to rendering the NPs the luminescence property. After the incorporation of GS-AuNPs onto the surface of SPIONs to form the hybrid nanoparticles (HBNPs), these SPIONs' protein adsorption was about 10-fold lower than those of the pure glutathione-coated SPIONs suggesting that GS-AuNPs are capable of providing a stealth effect against serum proteins. PMID:25029478

  20. Thermal decomposition of [Co(en)3][Fe(CN)6]∙ 2H2O: Topotactic dehydration process, valence and spin exchange mechanism elucidation

    PubMed Central

    2013-01-01

    Background The Prussian blue analogues represent well-known and extensively studied group of coordination species which has many remarkable applications due to their ion-exchange, electron transfer or magnetic properties. Among them, Co-Fe Prussian blue analogues have been extensively studied due to the photoinduced magnetization. Surprisingly, their suitability as precursors for solid-state synthesis of magnetic nanoparticles is almost unexplored. In this paper, the mechanism of thermal decomposition of [Co(en)3][Fe(CN)6] ∙∙ 2H2O (1a) is elucidated, including the topotactic dehydration, valence and spins exchange mechanisms suggestion and the formation of a mixture of CoFe2O4-Co3O4 (3:1) as final products of thermal degradation. Results The course of thermal decomposition of 1a in air atmosphere up to 600°C was monitored by TG/DSC techniques, 57Fe Mössbauer and IR spectroscopy. As first, the topotactic dehydration of 1a to the hemihydrate [Co(en)3][Fe(CN)6] ∙∙ 1/2H2O (1b) occurred with preserving the single-crystal character as was confirmed by the X-ray diffraction analysis. The consequent thermal decomposition proceeded in further four stages including intermediates varying in valence and spin states of both transition metal ions in their structures, i.e. [FeII(en)2(μ-NC)CoIII(CN)4], FeIII(NH2CH2CH3)2(μ-NC)2CoII(CN)3] and FeIII[CoII(CN)5], which were suggested mainly from 57Fe Mössbauer, IR spectral and elemental analyses data. Thermal decomposition was completed at 400°C when superparamagnetic phases of CoFe2O4 and Co3O4 in the molar ratio of 3:1 were formed. During further temperature increase (450 and 600°C), the ongoing crystallization process gave a new ferromagnetic phase attributed to the CoFe2O4-Co3O4 nanocomposite particles. Their formation was confirmed by XRD and TEM analyses. In-field (5 K / 5 T) Mössbauer spectrum revealed canting of Fe(III) spin in almost fully inverse spinel structure of CoFe2O4. Conclusions It has been found

  1. Quantum Suppression of Alignment in Ultrasmall Grains: Microwave Emission from Spinning Dust will be Negligibly Polarized

    NASA Astrophysics Data System (ADS)

    Draine, B. T.; Hensley, Brandon S.

    2016-11-01

    The quantization of energy levels in small, cold, free-flying nanoparticles suppresses dissipative processes that convert grain rotational kinetic energy into heat. For interstellar grains small enough to have ∼GHz rotation rates, the suppression of dissipation can be extreme. As a result, alignment of such grains is suppressed. This applies both to alignment of the grain body with its angular momentum {\\boldsymbol{J}}, and to alignment of {\\boldsymbol{J}} with the local magnetic field {\\boldsymbol{B}} 0. If the anomalous microwave emission is rotational emission from spinning grains, then it will be negligibly polarized at GHz frequencies, with P ≲ 10‑6 at ν > 10 GHz.

  2. Magnetoelectric ‘spin’ on stimulating the brain

    PubMed Central

    Guduru, Rakesh; Liang, Ping; Hong, J; Rodzinski, Alexandra; Hadjikhani, Ali; Horstmyer, Jeffrey; Levister, Ernest; Khizroev, Sakhrat

    2015-01-01

    Aim: The in vivo study on imprinting control region mice aims to show that magnetoelectric nanoparticles may directly couple the intrinsic neural activity-induced electric fields with external magnetic fields. Methods: Approximately 10 µg of CoFe2O4–BaTiO3 30-nm nanoparticles have been intravenously administrated through a tail vein and forced to cross the blood–brain barrier via a d.c. field gradient of 3000 Oe/cm. A surgically attached two-channel electroencephalography headmount has directly measured the modulation of intrinsic electric waveforms by an external a.c. 100-Oe magnetic field in a frequency range of 0–20 Hz. Results: The modulated signal has reached the strength comparable to that due the regular neural activity. Conclusion: The study opens a pathway to use multifunctional nanoparticles to control intrinsic fields deep in the brain. PMID:25953069

  3. Aqueous phase preparation of ultrasmall MoSe2 nanodots for efficient photothermal therapy of cancer cells

    NASA Astrophysics Data System (ADS)

    Yuwen, Lihui; Zhou, Jiajia; Zhang, Yuqian; Zhang, Qi; Shan, Jingyang; Luo, Zhimin; Weng, Lixing; Teng, Zhaogang; Wang, Lianhui

    2016-01-01

    Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation.Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation. Electronic supplementary information (ESI) available: Characterization, size distribution and EDS spectrum of MoSe2 NDs, calculation of

  4. Simulation of Ultra-Small MOSFETs Using a 2-D Quantum-Corrected Drift-Diffusion Model

    NASA Technical Reports Server (NTRS)

    Biegal, Bryan A.; Rafferty, Connor S.; Yu, Zhiping; Ancona, Mario G.; Dutton, Robert W.; Saini, Subhash (Technical Monitor)

    1998-01-01

    corrections do not have a large effect on the IN characteristics of electronic devices without heteroj unction s. On the other hand, ultra-small MOSFETs certainly exhibit important quantum effects that the DG model will include: quantum repulsion of the inversion and gate charges from the oxide interfaces, and quantum tunneling through thin gate oxides. We present initial results of 2-D DG simulations of ultra-small MOSFETs. Subtle but important issues involving the specification of the model, boundary conditions, and interface constraints for DG simulation of MOSFETs will also be illuminated.

  5. Nanoparticle cluster gas sensor: Pt activated SnO2 nanoparticles for NH3 detection with ultrahigh sensitivity.

    PubMed

    Liu, Xu; Chen, Nan; Han, Bingqian; Xiao, Xuechun; Chen, Gang; Djerdj, Igor; Wang, Yude

    2015-09-28

    Pt activated SnO2 nanoparticle clusters were synthesized by a simple solvothermal method. The structure, morphology, chemical state and specific surface area were analyzed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2-sorption studies, respectively. The SnO2 nanoparticle cluster matrix consists of tens of thousands of SnO2 nanoparticles with an ultra-small grain size estimated to be 3.0 nm. And there are abundant random-packed wormhole-like pores, caused by the inter-connection of the SnO2 nanoparticles, throughout each cluster. The platinum element is present in two forms including metal (Pt) and tetravalent metal oxide (PtO2) in the Pt activated SnO2 nanoparticle clusters. The as-synthesized pure and Pt activated SnO2 nanoparticle clusters were used to fabricate gas sensor devices. It was found that the gas response toward 500 ppm of ammonia was improved from 6.48 to 203.44 through the activation by Pt. And the results indicate that the sensor based on Pt activated SnO2 not only has ultrahigh sensitivity but also possesses good response-recovery properties, linear dependence, repeatability, selectivity and long-term stability, demonstrating the potential to use Pt activated SnO2 nanoparticle clusters as ammonia gas sensors. At the same time, the formation mechanisms of the unique nanoparticle clusters and highly enhanced sensitivity are also discussed. PMID:26289622

  6. Nanoparticle cluster gas sensor: Pt activated SnO2 nanoparticles for NH3 detection with ultrahigh sensitivity.

    PubMed

    Liu, Xu; Chen, Nan; Han, Bingqian; Xiao, Xuechun; Chen, Gang; Djerdj, Igor; Wang, Yude

    2015-09-28

    Pt activated SnO2 nanoparticle clusters were synthesized by a simple solvothermal method. The structure, morphology, chemical state and specific surface area were analyzed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2-sorption studies, respectively. The SnO2 nanoparticle cluster matrix consists of tens of thousands of SnO2 nanoparticles with an ultra-small grain size estimated to be 3.0 nm. And there are abundant random-packed wormhole-like pores, caused by the inter-connection of the SnO2 nanoparticles, throughout each cluster. The platinum element is present in two forms including metal (Pt) and tetravalent metal oxide (PtO2) in the Pt activated SnO2 nanoparticle clusters. The as-synthesized pure and Pt activated SnO2 nanoparticle clusters were used to fabricate gas sensor devices. It was found that the gas response toward 500 ppm of ammonia was improved from 6.48 to 203.44 through the activation by Pt. And the results indicate that the sensor based on Pt activated SnO2 not only has ultrahigh sensitivity but also possesses good response-recovery properties, linear dependence, repeatability, selectivity and long-term stability, demonstrating the potential to use Pt activated SnO2 nanoparticle clusters as ammonia gas sensors. At the same time, the formation mechanisms of the unique nanoparticle clusters and highly enhanced sensitivity are also discussed.

  7. Effect of iron oxide nanoparticles coating type on the relationship between nanoparticles concentration and signal intensity in inversion recovery T1-weighted MRI

    PubMed Central

    Gharehaghaji, Nahideh; Nazarpoor, Mahmood; Saharkhiz, Hodaiseh

    2015-01-01

    Background: Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are used as blood pool contrast agent for magnetic resonance angiography and perfusion imaging. Our aim in this study was to investigate the effect of the two coating types of iron oxide nanoparticles on the relationship between nanoparticles concentration and signal intensity (SI) in T1-weighted MR images. Methods: Different concentrations of the polyethylene glycol (PEG), and carboxydextran-coated iron oxide nanoparticles were imaged using inversion recovery Turbo-FLASH (Turbo fast low-angle shot) pulse sequence with inversion times (TIs) of 300-900 ms (interval of 100 ms). The maximum non-linear and linear relationship between the corrected SI (after non-uniformity correction) and the concentration of the two coated nanoparticles were calculated in T1-weighted images. Results: The maximum non-linear relationship between the corrected SI and the concentration of the PEG, and carboxydextran-coated nanoparticles were obtained at concentrations of 400 and 200 μmol Fe/L at a TI of 900 ms, respectively. In addition, the maximum linear relationship between the corrected SI and the concentration of the PEG, and carboxydextran-coated nanoparticles (R2=0.99) appeared at 228.184 and 205.654 μmolFe/L with a TI of 300 ms, respectively. Conclusion: The maximum non-linear corrected SI of the carboxydextran-coated nanoparticles was slightly higher than that of the PEG-coated nanoparticles at similar TIs. However, the PEG-coated nanoparticles were better than the carboxydextran-coated nanoparticles as a T1 contrast agent for perfusion measurements. PMID:26478869

  8. Hierarchical Pore Morphology of Cretaceous Shale: A Small-Angle Neutron Scattering and Ultrasmall-Angle Neutron Scattering Study

    SciTech Connect

    Bahadur, J.; Melnichenko, Y. B.; Mastalerz, Maria; Furmann, Agnieszka; Clarkson, Chris R.

    2014-09-25

    Shale reservoirs are becoming an increasingly important source of oil and natural gas supply and a potential candidate for CO2 sequestration. Understanding the pore morphology in shale may provide clues to making gas extraction more efficient and cost-effective. The porosity of Cretaceous shale samples from Alberta, Canada, collected from different depths with varying mineralogical compositions, has been investigated by small- and ultrasmall-angle neutron scattering. Moreover these samples come from the Second White Specks and Belle Fourche formations, and their organic matter content ranges between 2 and 3%. The scattering length density of the shale specimens has been estimated using the chemical composition of the different mineral components. Scattering experiments reveal the presence of fractal and non-fractal pores. It has been shown that the porosity and specific surface area are dominated by the contribution from meso- and micropores. The fraction of closed porosity has been calculated by comparing the porosities estimated by He pycnometry and scattering techniques. There is no correlation between total porosity and mineral components, a strong correlation has been observed between closed porosity and major mineral components in the studied specimens.

  9. A more informative approach for characterization of polymer monolithic phases: small angle neutron scattering/ultrasmall angle neutron scattering.

    PubMed

    Ford, Kathleen M; Konzman, Brian G; Rubinson, Judith F

    2011-12-15

    Neutron scattering techniques have been used frequently to characterize geological specimens and to determine the structures of glasses and of polymers as solutions, suspensions, or melts. Little work has been reported on their application in determining polymers' structural properties relevant to separations. Here, we present a comparison of characterization results from nitrogen porosimetry and from combined small angle neutron scattering (SANS) and ultrasmall angle neutron scattering (USANS) experiments. We show that SANS is extremely sensitive to the pore characteristics. Both approaches can provide information about porosity and pore characteristics, but the neutron scattering techniques provide additional information in the form of the surface characteristics of the pores and their length scales. Fits of the scattering data show that cylindrical pores are present with diameters down to 0.6 μm and that, for length scales down to approxmately 20 Å, the material shows self-similar (fractal) slopes of -3.4 to -3.6. Comparison of these characteristics with other examples from the scattering literature indicate that further investigation of their meaning for chromatographic media is required. PMID:22066706

  10. Solvent-like ligand-coated ultrasmall cadmium selenide nanocrystals: strong electronic coupling in a self-organized assembly.

    PubMed

    Lawrence, Katie N; Johnson, Merrell A; Dolai, Sukanta; Kumbhar, Amar; Sardar, Rajesh

    2015-07-21

    Strong inter-nanocrystal electronic coupling is a prerequisite for delocalization of exciton wave functions and high conductivity. We report 170 meV electronic coupling energy of short chain poly(ethylene glycol) thiolate-coated ultrasmall (<2.5 nm in diameter) CdSe semiconductor nanocrystals (SNCs) in solution. Cryo-transmission electron microscopy analysis showed the formation of a pearl-necklace assembly of nanocrystals in solution with regular inter-nanocrystal spacing. The electronic coupling was studied as a function of CdSe nanocrystal size where the smallest nanocrystals exhibited the largest coupling energy. The electronic coupling in spin-cast thin-film (<200 nm in thickness) of poly(ethylene glycol) thiolate-coated CdSe SNCs was studied as a function of annealing temperature, where an unprecedentedly large, ∼400 meV coupling energy was observed for 1.6 nm diameter SNCs, which were coated with a thin layer of poly(ethylene glycol) thiolates. Small-angle X-ray scattering measurements showed that CdSe SNCs maintained an order array inside the films. The strong electronic coupling of SNCs in a self-organized film could facilitate the large-scale production of highly efficient electronic materials for advanced optoelectronic device application. PMID:26098759

  11. Hierarchical Pore Morphology of Cretaceous Shale: A Small-Angle Neutron Scattering and Ultrasmall-Angle Neutron Scattering Study

    DOE PAGES

    Bahadur, J.; Melnichenko, Y. B.; Mastalerz, Maria; Furmann, Agnieszka; Clarkson, Chris R.

    2014-09-25

    Shale reservoirs are becoming an increasingly important source of oil and natural gas supply and a potential candidate for CO2 sequestration. Understanding the pore morphology in shale may provide clues to making gas extraction more efficient and cost-effective. The porosity of Cretaceous shale samples from Alberta, Canada, collected from different depths with varying mineralogical compositions, has been investigated by small- and ultrasmall-angle neutron scattering. Moreover these samples come from the Second White Specks and Belle Fourche formations, and their organic matter content ranges between 2 and 3%. The scattering length density of the shale specimens has been estimated using themore » chemical composition of the different mineral components. Scattering experiments reveal the presence of fractal and non-fractal pores. It has been shown that the porosity and specific surface area are dominated by the contribution from meso- and micropores. The fraction of closed porosity has been calculated by comparing the porosities estimated by He pycnometry and scattering techniques. There is no correlation between total porosity and mineral components, a strong correlation has been observed between closed porosity and major mineral components in the studied specimens.« less

  12. Protein fibrillation and nanoparticle interactions: opportunities and challenges

    NASA Astrophysics Data System (ADS)

    Mahmoudi, Morteza; Kalhor, Hamid R.; Laurent, Sophie; Lynch, Iseult

    2013-03-01

    Due to their ultra-small size, nanoparticles (NPs) have distinct properties compared with the bulk form of the same materials. These properties are rapidly revolutionizing many areas of medicine and technology. NPs are recognized as promising and powerful tools to fight against the human brain diseases such as multiple sclerosis or Alzheimer's disease. In this review, after an introductory part on the nature of protein fibrillation and the existing approaches for its investigations, the effects of NPs on the fibrillation process have been considered. More specifically, the role of biophysicochemical properties of NPs, which define their affinity for protein monomers, unfolded monomers, oligomers, critical nuclei, and other prefibrillar states, together with their influence on protein fibrillation kinetics has been described in detail. In addition, current and possible-future strategies for controlling the desired effect of NPs and their corresponding effects on the conformational changes of the proteins, which have significant roles in the fibrillation process, have been presented.

  13. Polymer nanocomposites exhibiting magnetically tunable microwave properties

    NASA Astrophysics Data System (ADS)

    Stojak, K.; Pal, S.; Srikanth, H.; Morales, C.; Dewdney, J.; Weller, T.; Wang, J.

    2011-04-01

    Polymer nanocomposites (PNCs) have been synthesized using Rogers polymer and CoFe2O4 nanoparticles (CFO NPs). X-ray diffraction (XRD) confirms the inverse spinel crystal structure of CFO NPs and transmission electron microscopy (TEM) images show the uniform dispersion of nanoparticles (10 nm ± 1) into the polymer matrix. Magnetic measurements indicate superparamagnetic response near room temperature for all PNCs. A blocking temperature TB ~ 298 K was observed and does not vary for different loading fractions of CFO NPs for the PNCs. The saturation magnetization (Ms) was found to be 11 emu g - 1 for 30 wt% CFO, increasing to 32 emu g - 1 for the 80 wt% CFO loaded PNC. A large value of coercivity (Hc = 19 kOe) is also observed at 10 K and is not affected by varying CFO loading. Microwave measurements show significant absorption in the 80 wt% CFO loading PNC and the quality factor shows a strong enhancement with applied magnetic field.

  14. Comparison of drug delivery potentials of surface functionalized cobalt and zinc ferrite nanohybrids for curcumin in to MCF-7 breast cancer cells

    NASA Astrophysics Data System (ADS)

    Sawant, V. J.; Bamane, S. R.; Shejwal, R. V.; Patil, S. B.

    2016-11-01

    The functionalization and surface engineering of CoFe2O4 and ZnFe2O4 nanoparticles were performed by coating with PEG and Chitosan respectively using simple wet co-precipitation. Then multiactive therapeutic drug curcumin was loaded to form drug delivery nanohybrids by precipitation. These nanohybrids were characterized separately using UV-vis, FTIR, PL spectroscopy, XRD, VSM, SEM and TEM analysis. The moderate antibacterial activities of the nanohybrids were elaborated by in vitro antibacterial screening on Escherichia coli and Staphylococcus aureus. The anticancer potentials, apoptotic effects and enhanced drug delivery properties of these nanohybrids were confirmed and compared on MCF-7 cells by in vitro MTT assay. The drug delivery activities for hydrophobic drug and anticancer effects of chitosan coated zinc ferrite functionalized nanoparticles were higher than PEG coated cobalt ferrite nanohybrids.

  15. Highly biocompatible and water-dispersible, amine functionalized magnetite nanoparticles, prepared by a low temperature, air-assisted polyol process: a new platform for bio-separation and diagnostics

    NASA Astrophysics Data System (ADS)

    Das, Manasmita; Dhak, Prasanta; Gupta, Satyajit; Mishra, Debasish; Maiti, Tapas K.; Basak, Amit; Pramanik, Panchanan

    2010-03-01

    A low temperature polyol process, based on glycolaldehyde mediated partial reduction of FeCl3·6H2O at 120 °C in the presence of sodium acetate as an alkali source and 2, 2'-(ethylenedioxy)-bis-(ethylamine) as an electrostatic stabilizer has been used for the gram-scale preparation of biocompatible, water-dispersible, amine functionalized magnetite nanoparticles (MNPs) with an average diameter of 6 ± 0.75 nm. With a reasonably high magnetization (37.8 e.m.u.) and amine groups on the outer surface of the nanoparticles, we demonstrated the magnetic separation and concentration implications of these ultrasmall particles in immunoassay. MRI studies indicated that these nanoparticles had the desired relaxivity for T2 contrast enhancement in vivo. In vitro biocompatibility, cell uptake and MR imaging studies established that these nanoparticles were safe in clinical dosages and by virtue of their ultrasmall sizes and positively charged surfaces could be easily internalized by cancer cells. All these positive attributes make these functional nanoparticles a promising platform for further in vitro and in vivo evaluations.

  16. In vitro radiosensitizing effects of ultrasmall gadolinium based particles on tumour cells.

    PubMed

    Mowat, P; Mignot, A; Rima, W; Lux, F; Tillement, O; Roulin, C; Dutreix, M; Bechet, D; Huger, S; Humbert, L; Barberi-Heyob, M; Aloy, M T; Armandy, E; Rodriguez-Lafrasse, C; Le Duc, G; Roux, S; Perriat, P

    2011-09-01

    Since radiotherapy is widely used in cancer treatment, it is essential to develop strategies which lower the irradiation burden while increasing efficacy and become efficient even in radio resistant tumors. Our new strategy is relying on the development of solid hybrid nanoparticles based on rare-earth such as gadolinium. In this paper, we then evidenced that gadolinium-based particles can be designed to enter efficiently into the human glioblastoma cell line U87 in quantities that can be tuned by modifying the incubation conditions. These sub-5 nm particles consist in a core of gadolinium oxide, a shell of polysiloxane and are functionalized by diethylenetriaminepentaacetic acid (DTPA). Although photoelectric effect is maximal in the [10-100 keV] range, such particles were found to possess efficient in-vitro radiosensitizing properties at an energy of 660 keV by using the "single-cell gel electrophoresis comet assay," an assay that measures the number of DNA damage that occurs during irradiation. Even more interesting, the particles have been evidenced by MTT assays to be also efficient radiosensitizers at an energy of 6 MeV for doses comprised between 2 and 8 Gy. The properties of the gadolinium-based particles give promising opening to a particle-assisted radio-therapy by using irradiation systems already installed in the majority of hospitals.

  17. Nanostructured materials for multifunctional applications under NSF-CREST research at Norfolk State University

    NASA Astrophysics Data System (ADS)

    Pradhan, A. K.; Mundle, R.; Zhang, K.; Holloway, T.; Amponsah, O.; Biswal, D.; Konda, R.; White, C.; Dondapati, H.; Santiago, K.; Birdsong, T.; Arslan, M.; Peeples, B.; Shaw, D.; Smak, J.; Samataray, C.; Bahoura, M.

    2012-04-01

    Magnetic nanoparticles of CoFe2O4 have been synthesized under an applied magnetic field through a co-precipitation method followed by thermal treatments at different temperatures, producing nanoparticles of varying size. The magnetic behavior of these nanoparticles of varying size was investigated. As-grown nanoparticles demonstrate superparamagnetism above the blocking temperature, which is dependent on the particle size. The anomalous magnetic behavior is attributed to the preferred Co ions and vacancies arrangements when the CoFe2O4 nanoparticles were synthesized under applied magnetic field. Furthermore, this magnetic property is strongly dependent on the high temperature heat treatments, which produce Co ions and vacancies disorder. We performed the fabrication of condensed and mesoporous silica coated CoFe2O4 magnetic nanocomposites. The CoFe2O4 magnetic nanoparticles were encapsulated with well-defined silica layer. The mesopores in the shell were fabricated as a consequence of removal of organic group of the precursor through annealing. The NiO nanoparticles were loaded into the mesoporous silica. The mesoporous silica coated magnetic nanostructure loaded with NiO as a final product may have potential use in the field of biomedical applications. Growth mechanism of ZnO nanorod arrays on ZnO seed layer investigated by electric and Kelvin probe force microscopy. Both electric and Kelvin force probe microscopy was used to investigate the surface potentials on the ZnO seed layer, which shows a remarkable dependence on the annealing temperature. The optimum temperature for the growth of nanorod arrays normal to the surface was found to be at 600 °C, which is in the range of right surface potentials and energy measured between 500 °C and 700 °C. We demonstrated from both EFM and Kelvin force probe microscopy studies that surface potential controls the growth of ZnO nanorods. This study will provide important understanding of growth of other nanostructures. Zn

  18. The High Radiosensitizing Efficiency of a Trace of Gadolinium-Based Nanoparticles in Tumors.

    PubMed

    Dufort, Sandrine; Le Duc, Géraldine; Salomé, Murielle; Bentivegna, Valerie; Sancey, Lucie; Bräuer-Krisch, Elke; Requardt, Herwig; Lux, François; Coll, Jean-Luc; Perriat, Pascal; Roux, Stéphane; Tillement, Olivier

    2016-01-01

    We recently developed the synthesis of ultrasmall gadolinium-based nanoparticles (GBN), (hydrodynamic diameter <5 nm) characterized by a safe behavior after intravenous injection (renal clearance, preferential accumulation in tumors). Owing to the presence of gadolinium ions, GBN can be used as contrast agents for magnetic resonance imaging (MRI) and as radiosensitizers. The attempt to determine the most opportune delay between the intravenous injection of GBN and the irradiation showed that a very low content of radiosensitizing nanoparticles in the tumor area is sufficient (0.1 μg/g of particles, i.e. 15 ppb of gadolinium) for an important increase of the therapeutic effect of irradiation. Such a promising and unexpected result is assigned to a suited distribution of GBN within the tumor, as revealed by the X-ray fluorescence (XRF) maps. PMID:27411781

  19. The High Radiosensitizing Efficiency of a Trace of Gadolinium-Based Nanoparticles in Tumors

    NASA Astrophysics Data System (ADS)

    Dufort, Sandrine; Le Duc, Géraldine; Salomé, Murielle; Bentivegna, Valerie; Sancey, Lucie; Bräuer-Krisch, Elke; Requardt, Herwig; Lux, François; Coll, Jean-Luc; Perriat, Pascal; Roux, Stéphane; Tillement, Olivier

    2016-07-01

    We recently developed the synthesis of ultrasmall gadolinium-based nanoparticles (GBN), (hydrodynamic diameter <5 nm) characterized by a safe behavior after intravenous injection (renal clearance, preferential accumulation in tumors). Owing to the presence of gadolinium ions, GBN can be used as contrast agents for magnetic resonance imaging (MRI) and as radiosensitizers. The attempt to determine the most opportune delay between the intravenous injection of GBN and the irradiation showed that a very low content of radiosensitizing nanoparticles in the tumor area is sufficient (0.1 μg/g of particles, i.e. 15 ppb of gadolinium) for an important increase of the therapeutic effect of irradiation. Such a promising and unexpected result is assigned to a suited distribution of GBN within the tumor, as revealed by the X-ray fluorescence (XRF) maps.

  20. The High Radiosensitizing Efficiency of a Trace of Gadolinium-Based Nanoparticles in Tumors

    PubMed Central

    Dufort, Sandrine; Le Duc, Géraldine; Salomé, Murielle; Bentivegna, Valerie; Sancey, Lucie; Bräuer-Krisch, Elke; Requardt, Herwig; Lux, François; Coll, Jean-Luc; Perriat, Pascal; Roux, Stéphane; Tillement, Olivier

    2016-01-01

    We recently developed the synthesis of ultrasmall gadolinium-based nanoparticles (GBN), (hydrodynamic diameter <5 nm) characterized by a safe behavior after intravenous injection (renal clearance, preferential accumulation in tumors). Owing to the presence of gadolinium ions, GBN can be used as contrast agents for magnetic resonance imaging (MRI) and as radiosensitizers. The attempt to determine the most opportune delay between the intravenous injection of GBN and the irradiation showed that a very low content of radiosensitizing nanoparticles in the tumor area is sufficient (0.1 μg/g of particles, i.e. 15 ppb of gadolinium) for an important increase of the therapeutic effect of irradiation. Such a promising and unexpected result is assigned to a suited distribution of GBN within the tumor, as revealed by the X-ray fluorescence (XRF) maps. PMID:27411781

  1. Solvent-like ligand-coated ultrasmall cadmium selenide nanocrystals: strong electronic coupling in a self-organized assembly

    NASA Astrophysics Data System (ADS)

    Lawrence, Katie N.; Johnson, Merrell A.; Dolai, Sukanta; Kumbhar, Amar; Sardar, Rajesh

    2015-07-01

    Strong inter-nanocrystal electronic coupling is a prerequisite for delocalization of exciton wave functions and high conductivity. We report 170 meV electronic coupling energy of short chain poly(ethylene glycol) thiolate-coated ultrasmall (<2.5 nm in diameter) CdSe semiconductor nanocrystals (SNCs) in solution. Cryo-transmission electron microscopy analysis showed the formation of a pearl-necklace assembly of nanocrystals in solution with regular inter-nanocrystal spacing. The electronic coupling was studied as a function of CdSe nanocrystal size where the smallest nanocrystals exhibited the largest coupling energy. The electronic coupling in spin-cast thin-film (<200 nm in thickness) of poly(ethylene glycol) thiolate-coated CdSe SNCs was studied as a function of annealing temperature, where an unprecedentedly large, ~400 meV coupling energy was observed for 1.6 nm diameter SNCs, which were coated with a thin layer of poly(ethylene glycol) thiolates. Small-angle X-ray scattering measurements showed that CdSe SNCs maintained an order array inside the films. The strong electronic coupling of SNCs in a self-organized film could facilitate the large-scale production of highly efficient electronic materials for advanced optoelectronic device application.Strong inter-nanocrystal electronic coupling is a prerequisite for delocalization of exciton wave functions and high conductivity. We report 170 meV electronic coupling energy of short chain poly(ethylene glycol) thiolate-coated ultrasmall (<2.5 nm in diameter) CdSe semiconductor nanocrystals (SNCs) in solution. Cryo-transmission electron microscopy analysis showed the formation of a pearl-necklace assembly of nanocrystals in solution with regular inter-nanocrystal spacing. The electronic coupling was studied as a function of CdSe nanocrystal size where the smallest nanocrystals exhibited the largest coupling energy. The electronic coupling in spin-cast thin-film (<200 nm in thickness) of poly(ethylene glycol) thiolate

  2. One-pot green synthesis of luminescent gold nanoparticles using imidazole derivative of chitosan.

    PubMed

    Nazirov, Alexander; Pestov, Alexander; Privar, Yuliya; Ustinov, Alexander; Modin, Evgeny; Bratskaya, Svetlana

    2016-10-20

    Water soluble luminescent gold nanoparticles with average size 2.3nm were for the first time synthesized by completely green method of Au(III) reduction using chitosan derivative-biocompatible nontoxic N-(4-imidazolyl)methylchitosan (IMC) as both reducing and stabilizing agent. Reduction of Au(III) to gold nanoparticles in IMC solution is a slow process, in which coordination power of biopolymer controls both reducing species concentration and gold crystal growth rate. Gold nanoparticles formed in IMC solution do not manifest surface plasmon resonance, but exhibit luminescence at 375nm under UV light excitation at 230nm. Due to biological activity of imidazolyl-containing polymers and their ability to bind proteins and drugs, the obtained ultra-small gold nanoparticles can find an application for biomolecules detection, bio-imaging, drug delivery, and catalysis. Very high catalytic activity (as compared to gold nanoparticles obtained by other green methods) was found for Au/IMC nanoparticles in the model reaction of p-nitrophenol reduction providing complete conversion of p-nitrophenol to p-aminophenol within 180-190s under mild conditions.

  3. Facile synthesis of ultrasmall monodisperse ``raisin-bun''-type MoO3/SiO2 nanocomposites with enhanced catalytic properties

    NASA Astrophysics Data System (ADS)

    Wang, Jiasheng; Li, Xin; Zhang, Shufen; Lu, Rongwen

    2013-05-01

    We report the preparation of ultrasmall monodisperse MoO3/SiO2 nanocomposites in reverse microemulsions formed by Brij-58/cyclohexane/water. The nanocomposites are of ``raisin-bun''-type with 1.0 +/- 0.2 nm MoO3 homogeneously dispersed in 23 +/- 2 nm silica spheres. Characterization is carried out based on transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrometry (EDS), X-ray powder diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectrometry (ICP-OES), N2 sorption measurement, and NH3 temperature-programmed desorption (NH3-TPD). The as-prepared MoO3/SiO2 nanocomposites are microporous and exhibit enhanced catalytic activities for acetalization of benzaldehyde with ethylene glycol and can be repeatedly used 5 times without obvious deactivation. The catalytic performance improvement is attributed to the unique structure and ultrasmall size of the nanocomposites.We report the preparation of ultrasmall monodisperse MoO3/SiO2 nanocomposites in reverse microemulsions formed by Brij-58/cyclohexane/water. The nanocomposites are of ``raisin-bun''-type with 1.0 +/- 0.2 nm MoO3 homogeneously dispersed in 23 +/- 2 nm silica spheres. Characterization is carried out based on transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrometry (EDS), X-ray powder diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectrometry (ICP-OES), N2 sorption measurement, and NH3 temperature-programmed desorption (NH3-TPD). The as-prepared MoO3/SiO2 nanocomposites are microporous and exhibit enhanced catalytic activities for acetalization of benzaldehyde with ethylene glycol and can be repeatedly used 5 times without obvious deactivation. The catalytic performance improvement is attributed to the unique

  4. Nonlinearly generated harmonic signals in ultra-small waveguides with magnetic films: Tunable enhancements of 2nd and 4th harmonics

    NASA Astrophysics Data System (ADS)

    Marsh, J.; Zagorodnii, V.; Celinski, Z.; Camley, R. E.

    2012-03-01

    The nonlinear generation of high harmonic signals (up to 5th harmonic) is explored in an ultra-small waveguide which contains a thin ferromagnetic film. The strength of the different harmonics is highly tunable. In particular, the power in the 2nd and 4th harmonic signals may be enhanced by over two orders of magnitude by varying the direction of a static magnetic field with respect to the long axis of the waveguide. In contrast, the 3rd and 5th harmonics are relatively insensitive to the direction of the magnetic field. The experimental results are explained by analytical and numerical calculations.

  5. Synthesis and structural characterization of magnetic cadmium sulfide-cobalt ferrite nanocomposite, and study of its activity for dyes degradation under ultrasound

    NASA Astrophysics Data System (ADS)

    Farhadi, Saeed; Siadatnasab, Firouzeh

    2016-11-01

    Cadmium sulfide-cobalt ferrite (CdS/CFO) nanocomposite was easily synthesized by one-step hydrothermal decomposition of cadmium diethyldithiocarbamate complex on the CoFe2O4 nanoparticles at 200 °C. Spectroscopic techniques of powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-visible spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and magnetic measurements were applied for characterizing the structure and morphology of the product. The results of FT-IR, XRD and EDX indicated that the CdS/CFO was highly pure. SEM and TEM results revealed that the CdS/CFO nanocomposite was formed from nearly uniform and sphere-like nanoparticles with the size of approximately 20 nm. The UV-vis absorption spectrum of the CdS/CFO nanocomposite showed the band gap of 2.21 eV, which made it suitable for sono-/photo catalytic purposes. By using the obtained CdS/CFO nanocomposite, an ultrasound-assisted advanced oxidation process (AOP) has been developed for catalytic degradation of methylene blue (MB), Rhodamine B (RhB), and methyl orange (MO)) in the presence of H2O2 as a green oxidant. CdS/CFO nanocomposite exhibited excellent sonocatalytic activity, so that, dyes were completely degraded in less than 10 min. The influences of crucial factors such as the H2O2 amount and catalyst dosage on the degradation efficiency were evaluated. The as-prepared CdS/CFO nanocomposite exhibited higher catalytic activity than pure CdS nanoparticles. Moreover, the magnetic property of CoFe2O4 made the nanocomposite recyclable.

  6. Silica nanoparticles separation from water: aggregation by cetyltrimethylammonium bromide (CTAB).

    PubMed

    Liu, Y; Tourbin, M; Lachaize, S; Guiraud, P

    2013-07-01

    Nanoparticles will inevitably be found in industrial and domestic wastes in the near future and as a consequence soon in water resources. Due to their ultra-small size, nanoparticles may not only have new hazards for environment and human health, but also cause low separation efficiency by classical water treatments processes. Thus, it would be an important challenge to develop a specific treatment with suitable additives for recovery of nanoparticles from waters. For this propose, this paper presents aggregation of silica nanoparticles (Klebosol 30R50 (75nm) and 30R25 (30nm)) by cationic surfactant cetyltrimethylammonium bromide (CTAB). Different mechanisms such as charge neutralization, "depletion flocculation" or "volume-restriction", and "hydrophobic effect" between hydrocarbon tails of CTAB have been proposed to explicate aggregation results. One important finding is that for different volume concentrations between 0.05% and 0.51% of 30R50 suspensions, the same critical coagulation concentration was observed at CTAB=0.1mM, suggesting the optimized quantity of CTAB during the separation process for nanoparticles of about 75nm. Furthermore, very small quantities of CTAB (0.01mM) can make 30R25 nanosilica aggregated due to the "hydrophobic effect". It is then possible to minimize the sludge and allow the separation process as "greener" as possible by studying this case. It has also shown that aggregation mechanisms can be different for very small particles so that a special attention has to be paid to the treatment of nanoparticles contained in water and wastewaters.

  7. Multiferroism and Magnetoelectric Coupling in Nano-Microscale Lead-Free Composite by 0.3Co-FERRITE and 0.7(K0.5Na0.5)NbO3-BASED Ferroelectric Matrix

    NASA Astrophysics Data System (ADS)

    Zhou, Yun; Wang, Xinyan; Li, Li; Su, Yuling; Zhang, Jincang; Cao, Shixun

    Nontoxic lead-free multiferroic composites are synthesized by incorporating the dispersed 0.3CoFe2O4 (CFO) ferromagnetic nanoparticles into 0.7(K0.5Na0.5) NbO3-LiSbO3 (KNN-LS5.2) ferroelectric micromatrix. The multiferroicity of the composite can be verified by polarization-electric field hysteresis loop and magnetic hysteresis loop. The composite exhibits excellent magnetic properties. A dilution effect is observed in magnetic hysteresis loops. The field dependence of ME voltage coefficient is given as a function of magnetic field from -4 kOe to 4 kOe with a maximum magnetoelectric voltage coefficient of 10.7 mVṡcm-1ṡOe-1 at the frequency of 1 kHz. It is a very high value in the lead-free magnetoelectric composites system for the potential use on multifunctional devices.

  8. Structural and magnetic properties of CoxFe3-xO4 versus Co/Fe molar ratio

    NASA Astrophysics Data System (ADS)

    Dippong, Thomas; Levei, Erika Andrea; Diamandescu, Lucian; Bibicu, Ion; Leostean, Cristian; Borodi, Gheorghe; Barbu Tudoran, Lucian

    2015-11-01

    CoxFe3-xO4 (x=0.5-2.5) magnetic nanoparticles were synthesized via redox reaction between cobalt nitrate, iron nitrate and 1-4-butanediol using five Co/Fe molar ratios, followed by calcination at 1000 °C. Single phase nanoscaled cobalt ferrite was obtained at x=1.0 and at slight Co excess (x=1.5), while at high Co/Fe molar ratios (x=2.0 and x=2.5) the prevailing phase was CoO accompanied by CoFe2O4 traces. The highest values of coercive field and saturation magnetization were obtained for the sample at x=1.0, while the lowest values were obtained in the sample with the highest Co excess (x=2.5). The results indicated that the used synthesis route was suitable for the synthesis of cobalt ferrite with moderate saturation magnetization and high coercive field values.

  9. Magnetic and ultrasonic studies on stable cobalt ferrite magnetic nanofluid.

    PubMed

    Nabeel Rashin, M; Hemalatha, J

    2014-03-01

    Stable cobalt ferrite nanofluids of various concentrations have been prepared through co-precipitation method. Structural and morphological studies of nanoparticles are made with the help of X-ray diffraction technique and Transmission Electron Microscope respectively and it is found that the particles exhibit face centered cubic structure with an average size of 14 nm. The magnetic properties of the nanofluids have been analyzed at room temperature which revealed ferromagnetic behavior and also the very low value of coupling constant which ensures the negligible interparticle interaction in the absence of magnetic field. Ultrasonic investigations have been made for the nanofluids at different temperatures and magnetic fields. The temperature effects are explained with the help of open and close-packed water structure. The inter particle interactions of surface modified CoFe2O4 particles and the cluster formation at higher concentrations are realized through the variations in ultrasonic parameters. PMID:24188514

  10. Magnetic Mesoporous Photonic Cellulose Films.

    PubMed

    Giese, Michael; Blusch, Lina K; Schlesinger, Maik; Meseck, Georg R; Hamad, Wadood Y; Arjmand, Mohammad; Sundararaj, Uttandaraman; MacLachlan, Mark J

    2016-09-13

    Novel hybrid materials of cellulose and magnetic nanoparticles (NPs) were synthesized and characterized. The materials combine the chiral nematic structural features of mesoporous photonic cellulose (MPC) with the magnetic properties of cobalt ferrite (CoFe2O4). The photonic, magnetic, and dielectric properties of the hybrid materials were investigated during the dynamic swelling and deswelling of the MPC films. It was observed that the dielectric properties of the generated MPC films increased tremendously following swelling in water, endorsing efficient swelling ability of the generated mesoporous films. The high magnetic permeability of the developed MPC films in conjunction with their superior dielectric properties, predominantly in the swollen state, makes them interesting for electromagnetic interference shielding applications. PMID:27588561

  11. Facile synthesis of ultrasmall monodisperse "raisin-bun"-type MoO3/SiO2 nanocomposites with enhanced catalytic properties.

    PubMed

    Wang, Jiasheng; Li, Xin; Zhang, Shufen; Lu, Rongwen

    2013-06-01

    We report the preparation of ultrasmall monodisperse MoO3/SiO2 nanocomposites in reverse microemulsions formed by Brij-58/cyclohexane/water. The nanocomposites are of "raisin-bun"-type with 1.0 ± 0.2 nm MoO3 homogeneously dispersed in 23 ± 2 nm silica spheres. Characterization is carried out based on transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrometry (EDS), X-ray powder diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectrometry (ICP-OES), N2 sorption measurement, and NH3 temperature-programmed desorption (NH3-TPD). The as-prepared MoO3/SiO2 nanocomposites are microporous and exhibit enhanced catalytic activities for acetalization of benzaldehyde with ethylene glycol and can be repeatedly used 5 times without obvious deactivation. The catalytic performance improvement is attributed to the unique structure and ultrasmall size of the nanocomposites. PMID:23613166

  12. Carbon Quantum Dots Induced Ultrasmall BiOI Nanosheets with Assembled Hollow Structures for Broad Spectrum Photocatalytic Activity and Mechanism Insight.

    PubMed

    Di, Jun; Xia, Jiexiang; Ji, Mengxia; Wang, Bin; Yin, Sheng; Xu, Hui; Chen, Zhigang; Li, Huaming

    2016-03-01

    Carbon quantum dots (CQDs) induced ultrasmall BiOI nanosheets with assembled hollow microsphere structures were prepared via ionic liquids 1-butyl-3-methylimidazolium iodine ([Bmim]I)-assisted synthesis method at room temperature condition. The composition, structure, morphology, and photoelectrochemical properties were investigated by multiple techniques. The CQDs/BiOI hollow microspheres structure displayed improved photocatalytic activities than pure BiOI for the degradation of three different kinds of pollutants, such as antibacterial agent tetracycline (TC), endocrine disrupting chemical bisphenol A (BPA), and phenol rhodamine B (RhB) under visible light, light above 580 nm, or light above 700 nm irradiation, which showed the broad spectrum photocatalytic activity. The key role of CQDs for the improvement of photocatalytic activity was explored. The introduction of CQDs could induce the formation of ultrasmall BiOI nanosheets with assembled hollow microsphere structure, strengthen the light absorption within full spectrum, increase the specific surface areas and improve the separation efficiency of the photogenerated electron-hole pairs. Benefiting from the unique structural features, the CQDs/BiOI microspheres exhibited excellent photoactivity. The h(+) was determined to be the main active specie for the photocatalytic degradation by ESR analysis and free radicals trapping experiments. The CQDs can be further employed to induce other nanosheets be smaller. The design of such architecture with CQDs/BiOI hollow microsphere structure can be extended to other photocatalytic systems.

  13. Polymeric nanoparticles-based topical delivery systems for the treatment of dermatological diseases

    PubMed Central

    Zhang, Zheng; Tsai, Pei-Chin; Ramezanli, Tannaz; Michniak-Kohn, Bozena B.

    2013-01-01

    Human skin not only functions as a permeation barrier (mainly due to the stratum corneum layer), but also provides a unique delivery pathway for therapeutic and other active agents. These compounds penetrate via intercellular, intracellular and transappendageal routes, resulting in topical delivery (into skin strata) and transdermal delivery (to subcutaneous tissues and into the systemic circulation). Passive and active permeation enhancement methods have been widely applied to increase the cutaneous penetration. The pathology, pathogenesis and topical treatment approaches of dermatological diseases, such as psoriasis, contact dermatitis, and skin cancer, are then discussed. Recent literature has demonstrated that nanoparticles-based topical delivery systems can be successful in treating these skin conditions. The studies are reviewed starting with the nanoparticles based on natural polymers specially chitosan, followed by those made of synthetic, degradable (aliphatic polyesters) and non-degradable (polyarylates) polymers; emphasis is given to nanospheres made of polymers derived from naturally occurring metabolites, the tyrosine-derived nanospheres (TyroSpheres™). In summary, the nanoparticles-based topical delivery systems combine the advantages of both the nano-sized drug carriers and the topical approach, and are promising for the treatment of skin diseases. For the perspectives, the penetration of ultra-small nanoparticles (size smaller than 40 nm) into skin strata, the targeted delivery of the encapsulated drugs to hair follicle stem cells, and the combination of nanoparticles and microneedle array technologies for special applications such as vaccine delivery are discussed. PMID:23386536

  14. Biotemplated Synthesis of Anatase Titanium Dioxide Nanoparticles via Lignocellulosic Waste Material

    PubMed Central

    Bagheri, Samira; Abd Hamid, Sharifah Bee

    2014-01-01

    Anatase titanium dioxide nanoparticles (TiO2-NPs) were synthesized by sol-gel method using rice straw as a soft biotemplate. Rice straw, as a lignocellulosic waste material, is a biomass feedstock which is globally produced in high rate and could be utilized in an innovative approach to manufacture a value-added product. Rice straw as a reliable biotemplate has been used in the sol-gel method to synthesize ultrasmall sizes of TiO2-NPs with high potential application in photocatalysis. The physicochemical properties of titanium dioxide nanoparticles were investigated by a number of techniques such as X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), ultraviolet visible spectra (UV-Vis), and surface area and pore size analysis. All results consensually confirmed that particle sizes of synthesized titanium dioxide were template-dependent, representing decrease in the nanoparticles sizes with increase of biotemplate concentration. Titanium dioxide nanoparticles as small as 13.0 ± 3.3 nm were obtained under our experimental conditions. Additionally, surface area and porosity of synthesized TiO2-NPs have been enhanced by increasing rice straw amount which results in surface modification of nanoparticles and potential application in photocatalysis. PMID:25126547

  15. Multipole plasmons and their disappearance in few-nanometre silver nanoparticles

    PubMed Central

    Raza, Søren; Kadkhodazadeh, Shima; Christensen, Thomas; Di Vece, Marcel; Wubs, Martijn; Mortensen, N. Asger; Stenger, Nicolas

    2015-01-01

    Electron energy-loss spectroscopy can be used for detailed spatial and spectral characterization of optical excitations in metal nanoparticles. In previous electron energy-loss experiments on silver nanoparticles with radii smaller than 20 nm, only the dipolar surface plasmon resonance was assumed to play a role. Here, applying electron energy-loss spectroscopy to individual silver nanoparticles encapsulated in silicon nitride, we observe besides the usual dipole resonance an additional surface plasmon resonance corresponding to higher angular momenta for nanoparticle radii as small as 4 nm. We study the radius and electron beam impact position dependence of both resonances separately. For particles smaller than 4 nm in radius the higher-order surface plasmon mode disappears, in agreement with generalized non-local optical response theory, while the dipole resonance blueshift exceeds our theoretical predictions. Unlike in optical spectra, multipole surface plasmons are important in electron energy-loss spectra even of ultrasmall metallic nanoparticles. PMID:26537568

  16. Liposomal nanoreactors for the synthesis of monodisperse palladium nanoparticles using glycerol.

    PubMed

    Clergeaud, Gael; Genç, Rükan; Ortiz, Mayreli; O'Sullivan, Ciara K

    2013-12-10

    The synthesis of highly stable ultrasmall monodisperse populations of palladium nanoparticles in the range of 1-3 nm in size was achieved via polyol reduction within 1,2-dioleoyl-sn-glycero-3-phosphor-rac-(1-glycerol) liposomal nanoreactors exploiting glycerol as both reducing and stabilizing agent. The liposome-based green method was compared with synthesis in solution, and the reducing agent concentration and the lipidic composition of the liposomal nanoreactors were demonstrated to have a strong effect on the final size and homogeneity of the palladium nanoparticles. Glycerol molecules acting as capping agent demonstrated the ability to stabilize the palladium nanoparticles over a long period of time, maintaining their homogeneity in size and shape. The obtained palladium nanoparticles were characterized using transmission electron microscopy, selected area electron diffraction, Fourier transform infrared and Raman spectroscopies, X-ray diffraction, and dynamic light scattering to determine their morphology, size, charge, surface chemistry, and crystal structure. The catalytic activity of the palladium nanoparticles was also tested for a reduction reaction.

  17. New Nanoparticles Dispersing Beads Mill with Ultra Small Beads and its Application

    NASA Astrophysics Data System (ADS)

    Inkyo, M.; Tahara, T.; Imajyo, Y.

    2011-10-01

    Two of the major problems related to nanoparticle dispersion with a conventional beads mill are re-agglomeration and damage to the crystalline structure of the particles. The Ultra Apex Mill was developed to solve these problems by enabling the use of ultra-small beads with a diameter of less than 0.1mm. The core of this breakthrough development is centrifugation technology which allows the use of beads as small as 0.015mm. When dispersing agglomerated nanoparticles the impulse of the small beads is very low which means there is little influence on the particles. The surface energy of the nanoparticles remains low so the properties are not likely to change. As a result, stable nanoparticle dispersions can be achieved without re-cohesion. The Ultra Apex Mill is superior to conventional beads mills that are limited to much larger bead sizes. The technology of the Ultra Apex Mill has pioneered practical applications for nanoparticles in various fields: composition materials for LCD screens, ink-jet printing, ceramic condensers and cosmetics.

  18. In-flow detection of ultra-small magnetic particles by an integrated giant magnetic impedance sensor

    NASA Astrophysics Data System (ADS)

    Fodil, K.; Denoual, M.; Dolabdjian, C.; Treizebre, A.; Senez, V.

    2016-04-01

    We have designed and fabricated a microfluidic system made of glass and polydimethylsiloxane. A micro-magnetometer has been integrated to the system. This sensor is made of a giant magneto-impedance wire known to have very high magnetic sensitivity at room temperature. A liquid-liquid segmented multiphase flow was generated in the channel using a Y-shaped inlet junction. The dispersed phase plugs contained superparamagnetic iron oxide (20 nm) nanoparticles at a molar concentration of 230 mmol/l. We have shown both theoretically and experimentally that in-flow detection of these nanoparticles is performed by the microsystem for concentration as small as 5.47 × 10-9 mol. These performances show that it is conceivable to use this system for ex-vivo analysis of blood samples where superparamagnetic iron oxide nanoparticles, initially used as magnetic contrast agents, could be functionalized for biomarkers fishing. It opens new perspectives in the context of personalized medicine.

  19. Nanoparticle scaffolds for syngas-fed solid oxide fuel cells

    SciTech Connect

    Boldrin, Paul; Ruiz-Trejo, Enrique; Yu, Jingwen; Gruar, Robert I.; Tighe, Christopher J.; Chang, Kee-Chul; Ilavsky, Jan; Darr, Jawwad A.; Brandon, Nigel

    2014-12-17

    Incorporation of nanoparticles into devices such as solid oxide fuel cells (SOFCs) may provide benefits such as higher surface areas or finer control over microstructure. However, their use with traditional fabrication techniques such as screen-printing is problematic. Here, we show that mixing larger commercial particles with nanoparticles allows traditional ink formulation and screen-printing to be used while still providing benefits of nanoparticles such as increased porosity and lower sintering temperatures. SOFC anodes were produced by impregnating ceria–gadolinia (CGO) scaffolds with nickel nitrate solution. The scaffolds were produced from inks containing a mixture of hydrothermally-synthesised nanoparticle CGO, commercial CGO and polymeric pore formers. The scaffolds were heat-treated at either 1000 or 1300 °C, and were mechanically stable. In situ ultra-small X-ray scattering (USAXS) shows that the nanoparticles begin sintering around 900–1000 °C. Analysis by USAXS and scanning electron microscopy (SEM) revealed that the low temperature heat-treated scaffolds possessed higher porosity. Impregnated scaffolds were used to produce symmetrical cells, with the lower temperature heat-treated scaffolds showing improved gas diffusion, but poorer charge transfer. Using these scaffolds, lower temperature heat-treated cells of Ni–CGO/200 μm YSZ/CGO-LSCF performed better at 700 °C (and below) in hydrogen, and performed better at all temperatures using syngas, with power densities of up to 0.15 W cm-2 at 800 °C. This approach has the potential to allow the use of a wider range of materials and finer control over microstructure.

  20. Nanoparticle scaffolds for syngas-fed solid oxide fuel cells

    DOE PAGES

    Boldrin, Paul; Ruiz-Trejo, Enrique; Yu, Jingwen; Gruar, Robert I.; Tighe, Christopher J.; Chang, Kee-Chul; Ilavsky, Jan; Darr, Jawwad A.; Brandon, Nigel

    2014-12-17

    Incorporation of nanoparticles into devices such as solid oxide fuel cells (SOFCs) may provide benefits such as higher surface areas or finer control over microstructure. However, their use with traditional fabrication techniques such as screen-printing is problematic. Here, we show that mixing larger commercial particles with nanoparticles allows traditional ink formulation and screen-printing to be used while still providing benefits of nanoparticles such as increased porosity and lower sintering temperatures. SOFC anodes were produced by impregnating ceria–gadolinia (CGO) scaffolds with nickel nitrate solution. The scaffolds were produced from inks containing a mixture of hydrothermally-synthesised nanoparticle CGO, commercial CGO and polymericmore » pore formers. The scaffolds were heat-treated at either 1000 or 1300 °C, and were mechanically stable. In situ ultra-small X-ray scattering (USAXS) shows that the nanoparticles begin sintering around 900–1000 °C. Analysis by USAXS and scanning electron microscopy (SEM) revealed that the low temperature heat-treated scaffolds possessed higher porosity. Impregnated scaffolds were used to produce symmetrical cells, with the lower temperature heat-treated scaffolds showing improved gas diffusion, but poorer charge transfer. Using these scaffolds, lower temperature heat-treated cells of Ni–CGO/200 μm YSZ/CGO-LSCF performed better at 700 °C (and below) in hydrogen, and performed better at all temperatures using syngas, with power densities of up to 0.15 W cm-2 at 800 °C. This approach has the potential to allow the use of a wider range of materials and finer control over microstructure.« less

  1. Ultra-dispersed Pt nanoparticles on SAPO-34/γ-Al2O3 support for efficient propane dehydrogenation.

    PubMed

    Chu, Yue; Zhang, Qiang; Wu, Tongwei; Nawaz, Zeeshan; Wang, Yao; Wei, Fei

    2014-09-01

    Ultra-dispersed precious metal nanoparticles with good thermal stability are highly required for heterogeneous catalysis. However, the efficient and effective strategy to disperse ultra-fine precious metal nanoparticles at high reaction temperature is still not fully understood yet. In this contribution, a family of catalysts with ultra-small Pt nanoparticles were prepared using impregnation method by adjusting the zeolite content in the SAPO-34 and γ-Al2O3 mixed support. The effect of Pt nanoparticle size on the catalytic activity, selectivity, and stability was investigated in the propane dehydrogenation reaction. Catalyst with smaller Pt particles exhibits better catalytic performance. Both the highest Pt dispersion and the best catalytic activity can be achieved by using SAPO-34 and γ-Al2O3 mixed support with 70 wt.% of SAPO-34. The size and structure of the Pt nanoparticles on the optimal catalyst were characterized by transmission electron microscopy. Pt nanoparticles with an average size of 1.32 nm were observed. There were stronger metal-support interactions between the oxidized tin species and Pt particles on SAPO-34 support compared to that on γ-Al2O3 catalyst. These lead to high Pt dispersion and consequently good catalytic performance. PMID:25924347

  2. Intermetallic nanoparticles

    SciTech Connect

    Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules

    2015-07-14

    A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

  3. Intermetallic nanoparticles

    SciTech Connect

    Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules L.

    2015-11-20

    A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

  4. Direct Measurement of Photon Recoil from a Levitated Nanoparticle

    NASA Astrophysics Data System (ADS)

    Jain, Vijay; Gieseler, Jan; Moritz, Clemens; Dellago, Christoph; Quidant, Romain; Novotny, Lukas

    2016-06-01

    The momentum transfer between a photon and an object defines a fundamental limit for the precision with which the object can be measured. If the object oscillates at a frequency Ω0 , this measurement backaction adds quanta ℏΩ0 to the oscillator's energy at a rate Γrecoil, a process called photon recoil heating, and sets bounds to coherence times in cavity optomechanical systems. Here, we use an optically levitated nanoparticle in ultrahigh vacuum to directly measure Γrecoil. By means of a phase-sensitive feedback scheme, we cool the harmonic motion of the nanoparticle from ambient to microkelvin temperatures and measure its reheating rate under the influence of the radiation field. The recoil heating rate is measured for different particle sizes and for different excitation powers, without the need for cavity optics or cryogenic environments. The measurements are in quantitative agreement with theoretical predictions and provide valuable guidance for the realization of quantum ground-state cooling protocols and the measurement of ultrasmall forces.

  5. Direct Measurement of Photon Recoil from a Levitated Nanoparticle.

    PubMed

    Jain, Vijay; Gieseler, Jan; Moritz, Clemens; Dellago, Christoph; Quidant, Romain; Novotny, Lukas

    2016-06-17

    The momentum transfer between a photon and an object defines a fundamental limit for the precision with which the object can be measured. If the object oscillates at a frequency Ω_{0}, this measurement backaction adds quanta ℏΩ_{0} to the oscillator's energy at a rate Γ_{recoil}, a process called photon recoil heating, and sets bounds to coherence times in cavity optomechanical systems. Here, we use an optically levitated nanoparticle in ultrahigh vacuum to directly measure Γ_{recoil}. By means of a phase-sensitive feedback scheme, we cool the harmonic motion of the nanoparticle from ambient to microkelvin temperatures and measure its reheating rate under the influence of the radiation field. The recoil heating rate is measured for different particle sizes and for different excitation powers, without the need for cavity optics or cryogenic environments. The measurements are in quantitative agreement with theoretical predictions and provide valuable guidance for the realization of quantum ground-state cooling protocols and the measurement of ultrasmall forces. PMID:27367388

  6. Fluorescent nanoparticle interactions with biological systems: What have we learned so far?

    NASA Astrophysics Data System (ADS)

    Shang, Li; Nienhaus, Gerd Ulrich

    2015-03-01

    Fluorescent nanoparticles (NPs) are promising optical probes for biological and biomedical applications, thanks to their excellent photophysical properties, color tunability and facile bioconjugation. It still remains unclear, however, how fluorescent NPs behave in the complex biological environment. Our group has quantified interactions of different fluorescent NPs (i.e., semiconductor quantum dots and metal nanoclusters) with serum proteins and living cells by the combined use of different spectroscopic and microscopic techniques. Our studies show that (1) interactions with proteins may significantly alter the photophysical properties of the NPs as well as the responses of cells internalizing them; (2) protein surface charge distributions play an important role in the interactions of NPs with proteins and cells; (3) ultrasmall NPs (diameter less than 10 nm) show a cellular internalization behavior that is distinctly different from the one observed with larger particles (diameter ~100 nm).

  7. CdTe quantum dots induce activation of human platelets: implications for nanoparticle hemocompatibility

    PubMed Central

    Samuel, Stephen P; Santos-Martinez, Maria J; Medina, Carlos; Jain, Namrata; Radomski, Marek W; Prina-Mello, Adriele; Volkov, Yuri

    2015-01-01

    New nanomaterials intended for systemic administration have raised concerns regarding their biocompatibility and hemocompatibility. Quantum dots (QD) nanoparticles have been used for diagnostics, and recent work suggests their use for in vivo molecular and cellular imaging. However, the hemocompatibility of QDs and their constituent components has not been fully elucidated. In the present study, comprehensive investigation of QD–platelet interactions is presented. These interactions were shown using transmission electron microscopy. The effects of QDs on platelet function were investigated using light aggregometry, quartz crystal microbalance with dissipation, flow cytometry, and gelatin zymography. Platelet morphology was also analyzed by phase-contrast, immunofluorescence, atomic-force and transmission electron microscopy. We show that the QDs bind to platelet plasma membrane with the resultant upregulation of glycoprotein IIb/IIIa and P-selectin receptors, and release of matrix metalloproteinase-2. These findings unravel for the first time the mechanism of functional response of platelets to ultrasmall QDs in vitro. PMID:25897218

  8. CdTe quantum dots induce activation of human platelets: implications for nanoparticle hemocompatibility.

    PubMed

    Samuel, Stephen P; Santos-Martinez, Maria J; Medina, Carlos; Jain, Namrata; Radomski, Marek W; Prina-Mello, Adriele; Volkov, Yuri

    2015-01-01

    New nanomaterials intended for systemic administration have raised concerns regarding their biocompatibility and hemocompatibility. Quantum dots (QD) nanoparticles have been used for diagnostics, and recent work suggests their use for in vivo molecular and cellular imaging. However, the hemocompatibility of QDs and their constituent components has not been fully elucidated. In the present study, comprehensive investigation of QD-platelet interactions is presented. These interactions were shown using transmission electron microscopy. The effects of QDs on platelet function were investigated using light aggregometry, quartz crystal microbalance with dissipation, flow cytometry, and gelatin zymography. Platelet morphology was also analyzed by phase-contrast, immunofluorescence, atomic-force and transmission electron microscopy. We show that the QDs bind to platelet plasma membrane with the resultant upregulation of glycoprotein IIb/IIIa and P-selectin receptors, and release of matrix metalloproteinase-2. These findings unravel for the first time the mechanism of functional response of platelets to ultrasmall QDs in vitro. PMID:25897218

  9. Nanoparticle cluster gas sensor: Pt activated SnO2 nanoparticles for NH3 detection with ultrahigh sensitivity

    NASA Astrophysics Data System (ADS)

    Liu, Xu; Chen, Nan; Han, Bingqian; Xiao, Xuechun; Chen, Gang; Djerdj, Igor; Wang, Yude

    2015-09-01

    Pt activated SnO2 nanoparticle clusters were synthesized by a simple solvothermal method. The structure, morphology, chemical state and specific surface area were analyzed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2-sorption studies, respectively. The SnO2 nanoparticle cluster matrix consists of tens of thousands of SnO2 nanoparticles with an ultra-small grain size estimated to be 3.0 nm. And there are abundant random-packed wormhole-like pores, caused by the inter-connection of the SnO2 nanoparticles, throughout each cluster. The platinum element is present in two forms including metal (Pt) and tetravalent metal oxide (PtO2) in the Pt activated SnO2 nanoparticle clusters. The as-synthesized pure and Pt activated SnO2 nanoparticle clusters were used to fabricate gas sensor devices. It was found that the gas response toward 500 ppm of ammonia was improved from 6.48 to 203.44 through the activation by Pt. And the results indicate that the sensor based on Pt activated SnO2 not only has ultrahigh sensitivity but also possesses good response-recovery properties, linear dependence, repeatability, selectivity and long-term stability, demonstrating the potential to use Pt activated SnO2 nanoparticle clusters as ammonia gas sensors. At the same time, the formation mechanisms of the unique nanoparticle clusters and highly enhanced sensitivity are also discussed.Pt activated SnO2 nanoparticle clusters were synthesized by a simple solvothermal method. The structure, morphology, chemical state and specific surface area were analyzed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2-sorption studies, respectively. The SnO2 nanoparticle cluster matrix consists of tens of thousands of SnO2 nanoparticles with an ultra-small grain size estimated to be 3.0 nm. And there are abundant random-packed wormhole-like pores, caused by the inter

  10. Paramagnetic dysprosium oxide nanoparticles and dysprosium hydroxide nanorods as T₂ MRI contrast agents.

    PubMed

    Kattel, Krishna; Park, Ja Young; Xu, Wenlong; Kim, Han Gyeol; Lee, Eun Jung; Bony, Badrul Alam; Heo, Woo Choul; Jin, Seonguk; Baeck, Jong Su; Chang, Yongmin; Kim, Tae Jeong; Bae, Ji Eun; Chae, Kwon Seok; Lee, Gang Ho

    2012-04-01

    We report here paramagnetic dysprosium nanomaterial-based T(2) MRI contrast agents. A large r(2) and a negligible r(1) is an ideal condition for T(2) MR imaging. At this condition, protons are strongly and nearly exclusively induced for T(2) MR imaging. The dysprosium nanomaterials fairly satisfy this because they are found to possess a decent r(2) but a negligible r(1) arising from L + S state 4f-electrons in Dy(III) ion ((6)H(15/2)). Their r(2) will also further increase with increasing applied field because of unsaturated magnetization at room temperature. Therefore, MR imaging and various physical properties of the synthesized d-glucuronic acid coated ultrasmall dysprosium oxide nanoparticles (d(avg) = 3.2 nm) and dysprosium hydroxide nanorods (20 × 300 nm) are investigated. These include hydrodynamic diameters, magnetic properties, MR relaxivities, cytotoxicities, and 3 tesla in vivo T(2) MR images. Here, MR imaging properties of dysprosium hydroxide nanorods have not been reported so far. These two samples show r(2)s of 65.04 and 181.57 s(-1)mM(-1), respectively, with negligible r(1)s at 1.5 tesla and at room temperature, no in vitro cytotoxicity up to 100 μM Dy, and clear negative contrast enhancements in 3 tesla in vivo T(2) MR images of a mouse liver, which will be even more improved at higher MR fields. Therefore, d-glucuronic acid coated ultrasmall dysprosium oxide nanoparticles with renal excretion can be a potential candidate as a sensitive T(2) MRI contrast agent at MR field greater than 3 tesla.

  11. Surface modification of gadolinium oxide thin films and nanoparticles using poly(ethylene glycol)-phosphate.

    PubMed

    Guay-Bégin, Andrée-Anne; Chevallier, Pascale; Faucher, Luc; Turgeon, Stéphane; Fortin, Marc-André

    2012-01-10

    The performance of nanomaterials for biomedical applications is highly dependent on the nature and the quality of surface coatings. In particular, the development of functionalized nanoparticles for magnetic resonance imaging (MRI) requires the grafting of hydrophilic, nonimmunogenic, and biocompatible polymers such as poly(ethylene glycol) (PEG). Attached at the surface of nanoparticles, this polymer enhances the steric repulsion and therefore the stability of the colloids. In this study, phosphate molecules were used as an alternative to silanes or carboxylic acids, to graft PEG at the surface of ultrasmall gadolinium oxide nanoparticles (US-Gd(2)O(3), 2-3 nm diameter). This emerging, high-sensitivity "positive" contrast agent is used for signal enhancement in T(1)-weighted molecular and cellular MRI. Comparative grafting assays were performed on Gd(2)O(3) thin films, which demonstrated the strong reaction of phosphate with Gd(2)O(3) compared to silane and carboxyl groups. Therefore, PEG-phosphate was preferentially used to coat US-Gd(2)O(3) nanoparticles. The grafting of this polymer on the particles was confirmed by XPS and FTIR. These analyses also demonstrated the strong attachment of PEG-phosphate at the surface of Gd(2)O(3), forming a protective layer on the nanoparticles. The stability in aqueous solution, the relaxometric properties, and the MRI signal of PEG-phosphate-covered Gd(2)O(3) particles were also better than those from non-PEGylated nanoparticles. As a result, reacting PEG-phosphate with Gd(2)O(3) particles is a promising, rapid, one-step procedure to PEGylate US-Gd(2)O(3) nanoparticles, an emerging "positive" contrast agent for preclinical molecular and cellular applications.

  12. Precision Nanoparticles

    SciTech Connect

    John Hemminger

    2009-07-21

    A revolutionary technology that efficiently produces nanoparticles in uniform and prescribed sizes (1-100 nanometers) using supercritical fluids. INL researcher Robert Fox was joined by Idaho State University researchers Rene Rodriquez and Joshua Pak in d

  13. Precision Nanoparticles

    ScienceCinema

    John Hemminger

    2016-07-12

    A revolutionary technology that efficiently produces nanoparticles in uniform and prescribed sizes (1-100 nanometers) using supercritical fluids. INL researcher Robert Fox was joined by Idaho State University researchers Rene Rodriquez and Joshua Pak in d

  14. Synthesis of semiconductor nanoparticles.

    PubMed

    Chen, Xianfeng; Dobson, Peter J

    2012-01-01

    Here, we describe typical methods and provide detailed experimental protocols for synthesizing and processing various semiconductor nanoparticles which have potential application in biology and medicine. These include synthesis of binary semiconductor nanoparticles; core@shell nanoparticles and alloyed nanoparticles; size-selective precipitation to obtain monodisperse nanoparticles; and strategies for phase transfer of nanoparticles from organic solution to aqueous media. PMID:22791427

  15. Nanoparticle vaccines.

    PubMed

    Zhao, Liang; Seth, Arjun; Wibowo, Nani; Zhao, Chun-Xia; Mitter, Neena; Yu, Chengzhong; Middelberg, Anton P J

    2014-01-01

    Nanotechnology increasingly plays a significant role in vaccine development. As vaccine development orientates toward less immunogenic "minimalist" compositions, formulations that boost antigen effectiveness are increasingly needed. The use of nanoparticles in vaccine formulations allows not only improved antigen stability and immunogenicity, but also targeted delivery and slow release. A number of nanoparticle vaccines varying in composition, size, shape, and surface properties have been approved for human use and the number of candidates is increasing. However, challenges remain due to a lack of fundamental understanding regarding the in vivo behavior of nanoparticles, which can operate as either a delivery system to enhance antigen processing and/or as an immunostimulant adjuvant to activate or enhance immunity. This review provides a broad overview of recent advances in prophylactic nanovaccinology. Types of nanoparticles used are outlined and their interaction with immune cells and the biosystem are discussed. Increased knowledge and fundamental understanding of nanoparticle mechanism of action in both immunostimulatory and delivery modes, and better understanding of in vivo biodistribution and fate, are urgently required, and will accelerate the rational design of nanoparticle-containing vaccines. PMID:24295808

  16. Magnetic PEGylated Pt3Co nanoparticles as a novel MR contrast agent: in vivo MR imaging and long-term toxicity study

    NASA Astrophysics Data System (ADS)

    Yin, Shengnan; Li, Zhiwei; Cheng, Liang; Wang, Chao; Liu, Yumeng; Chen, Qian; Gong, Hua; Guo, Liang; Li, Yonggang; Liu, Zhuang

    2013-11-01

    Magnetic resonance (MR) imaging using magnetic nanoparticles as the contrast agent has been extensively explored in biomedical imaging and disease diagnosis. Herein, we develop biocompatible polymer coated ultra-small Pt3Co magnetic nanoparticles as a new T2-weighted MR imaging contrast agent. A unique class of alloy Pt3Co nanoparticles is synthesized through a thermal decomposition method. After being modified with polyethylene glycol (PEG), the obtained Pt3Co-PEG nanoparticles exhibit an extremely high T2-weighted relaxivity rate (r2) up to 451.2 mM s-1, which is much higher than that of Resovist®, a commercial T2-MR contrast agent used in the clinic. In vitro experiments indicate no obvious cytotoxicity of Pt3Co-PEG nanoparticles to various cell lines. After intravenous injection of Pt3Co-PEG nanoparticles, in vivo T2-weighted MR imaging of tumor-bearing mice reveals strong tumor contrast, which is much higher than that offered by injecting Resovist®. We further study the long-term biodistribution and toxicology of this new type of MR contrast nanoparticles after intravenous injection into healthy mice. Despite the significant retention of Pt3Co-PEG nanoparticles in the mouse liver and spleen, no appreciable toxicity of these nanoparticles to the treated animals has been noted in our detailed histological and hematological analysis over a course of 60 days. Our work demonstrates that functionalized Pt3Co nanoparticles may be a promising new type of T2-weighted MR contrast agent potentially useful in biomedical imaging and diagnosis.Magnetic resonance (MR) imaging using magnetic nanoparticles as the contrast agent has been extensively explored in biomedical imaging and disease diagnosis. Herein, we develop biocompatible polymer coated ultra-small Pt3Co magnetic nanoparticles as a new T2-weighted MR imaging contrast agent. A unique class of alloy Pt3Co nanoparticles is synthesized through a thermal decomposition method. After being modified with polyethylene

  17. Refinement of adsorptive coatings for fluorescent riboflavin-receptor-targeted iron oxide nanoparticles.

    PubMed

    Tsvetkova, Yoanna; Beztsinna, Nataliia; Jayapaul, Jabadurai; Weiler, Marek; Arns, Susanne; Shi, Yang; Lammers, Twan; Kiessling, Fabian

    2016-01-01

    Flavin mononucleotide (FMN) is a riboflavin derivative that can be exploited to target the riboflavin transporters (RFTs) and the riboflavin carrier protein (RCP) in cells with high metabolic activity. In this study we present the synthesis of different FMN-coated ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) and their efficiency as targeting contrast agents. Since FMN alone cannot stabilize the nanoparticles, we used adenosine phosphates--AMP, ADP and ATP--as spacers to obtain colloidally stable nanoparticles. Nucleotides with di- and triphosphate groups were intended to increase the USPIO charge and thus improve zeta potential and stability. However, all nanoparticles formed negatively charged clusters with similar properties in terms of zeta potential (-28 ± 2 mV), relaxivity (228-259 mM(-1) s(-1) at 3 T) and hydrodynamic radius (53-85 nm). Molecules with a higher number of phosphate groups, such as ADP and ATP, have a higher adsorption affinity towards iron oxide, which, instead of providing more charge, led to partial desorption and replacement of FMN. Hence, we obtained USPIOs carrying different amounts of targeting agent, which significantly influenced the nanoparticles' uptake. The nanoparticles' uptake by different cancer cells and HUVECs was evaluated photometrically and with MR relaxometry, showing that the cellular uptake of the USPIOs increases with the FMN amount on their surface. Thus, for USPIOs targeted with riboflavin derivatives the use of spacers with increasing numbers of phosphate groups does not improve either zeta potential or the particles' stability, but rather detaches the targeting moieties from their surface, leading to lower cellular uptake.

  18. Superparamagnetic iron oxide nanoparticles as radiosensitizer via enhanced reactive oxygen species formation

    SciTech Connect

    Klein, Stefanie; Sommer, Anja; Distel, Luitpold V.R.; Neuhuber, Winfried; Kryschi, Carola

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Ultrasmall citrate-coated SPIONs with {gamma}Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} structure were prepared. Black-Right-Pointing-Pointer SPIONs uptaken by MCF-7 cells increase the ROS production for about 240%. Black-Right-Pointing-Pointer The SPION induced ROS production is due to released iron ions and catalytically active surfaces. Black-Right-Pointing-Pointer Released iron ions and SPION surfaces initiate the Fenton and Haber-Weiss reaction. Black-Right-Pointing-Pointer X-ray irradiation of internalized SPIONs leads to an increase of catalytically active surfaces. -- Abstract: Internalization of citrate-coated and uncoated superparamagnetic iron oxide nanoparticles by human breast cancer (MCF-7) cells was verified by transmission electron microscopy imaging. Cytotoxicity studies employing metabolic and trypan blue assays manifested their excellent biocompatibility. The production of reactive oxygen species in iron oxide nanoparticle loaded MCF-7 cells was explained to originate from both, the release of iron ions and their catalytically active surfaces. Both initiate the Fenton and Haber-Weiss reaction. Additional oxidative stress caused by X-ray irradiation of MCF-7 cells was attributed to the increase of catalytically active iron oxide nanoparticle surfaces.

  19. Ferumoxytol nanoparticle uptake in brain during acute neuroinflammation is cell-specific.

    PubMed

    McConnell, Heather L; Schwartz, Daniel L; Richardson, Brian E; Woltjer, Randall L; Muldoon, Leslie L; Neuwelt, Edward A

    2016-08-01

    Ferumoxytol ultrasmall superparamagnetic iron oxide nanoparticles can enhance contrast between neuroinflamed and normal-appearing brain tissue when used as a contrast agent for high-sensitivity magnetic resonance imaging (MRI). Here we used an anti-dextran antibody (Dx1) that binds the nanoparticle's carboxymethyldextran coating to differentiate ferumoxytol from endogenous iron and localize it unequivocally in brain tissue. Intravenous injection of ferumoxytol into immune-competent rats that harbored human tumor xenograft-induced inflammatory brain lesions resulted in heterogeneous and lesion-specific signal enhancement on MRI scans in vivo. We used Dx1 immunolocalization and electron microscopy to identify ferumoxytol in affected tissue post-MRI. We found that ferumoxytol nanoparticles were taken up by astrocyte endfeet surrounding cerebral vessels, astrocyte processes, and CD163(+)/CD68(+) macrophages, but not by tumor cells. These results provide a biological basis for the delayed imaging changes seen with ferumoxytol and indicate that ferumoxytol-MRI can be used to assess the inflammatory component of brain lesions in the clinic. PMID:27071335

  20. Longitudinal 3He and proton imaging of magnetite biodistribution in a rat model of instilled nanoparticles.

    PubMed

    Al Faraj, Achraf; Lacroix, Ghislaine; Alsaid, Hasan; Elgrabi, Dan; Stupar, Vasile; Robidel, Franck; Gaillard, Sophie; Canet-Soulas, Emmanuelle; Crémillieux, Yannick

    2008-06-01

    Epidemiological and toxicological studies have provided evidence that accidentally inhaled nanosize ultrafine particles can induce chronic or acute health damage. MRI, being noninvasive, is able to assess the biodistribution and clearance of magnetically labeled nanoparticles induced by instillation or inhalation. We report 3He and proton MRI follow-up of lung, liver, spleen, and kidney distribution of USPIO (ultrasmall superparamagnetic iron oxide) in a rat model. The sensitivity of the imaging technique to various concentrations of instilled magnetite suspension was first assessed in vivo (n=12). A 2-week longitudinal imaging study was then performed on animals (n=7) instilled with a 0.5 mg magnetite solution. Hypointense and void signal regions associated with intrapulmonary USPIO were observed in the 3He ventilation images throughout the study, whereas no USPIO-related proton signal intensity changes were found. Intrapulmonary magnetite nanoparticle confinement was confirmed by ex vivo iron assay and histological analysis. This study demonstrates that combined 3He and proton MRI enables noninvasive assessment of the distribution and clearance of magnetically labeled instilled nanoparticles.

  1. High-Density Lipoproteins (HDL) – Nature’s Multi-Functional Nanoparticles

    PubMed Central

    Kuai, Rui; Li, Dan; Chen, Y. Eugene; Moon, James J.; Schwendeman, Anna

    2016-01-01

    High-density lipoproteins (HDL) are endogenous nanoparticles involved in the transport and metabolism of cholesterol, phospholipids, and triglycerides. HDL is well known as the ―good‖ cholesterol because it not only removes excess cholesterol from atherosclerotic plaques but also has anti-inflammatory and anti-oxidative properties, which protect the cardiovascular system. Circulating HDL also transports endogenous proteins, vitamins, hormones, and microRNA to various organs. Compared with other synthetic nanocarriers, such as liposomes, micelles, inorganic and polymeric nanoparticles, HDL has unique features that allow them to deliver cargo to specific targets more efficiently. These attributes include their ultra-small size (8-12 nm in diameter), high tolerability in humans (up to 8 g of protein per infusion), long circulating half-life (12-24 hours), and intrinsic targeting properties to different recipient cells. Various recombinant ApoA proteins and ApoA mimetic peptides have been recently developed for the preparation of reconstituted HDL that exhibits properties similar to endogenous HDL and has a potential for industrial scale-up. In this review, we will summarize: a) clinical pharmacokinetics and safety of reconstituted HDL products, b) comparison of HDL with inorganic and other organic nanoparticles, c) the rationale for using HDL as drug delivery vehicles for important therapeutic indications, d) the current state-of-the-art in HDL production, and e) HDL-based drug delivery strategies for small molecules, peptides/proteins, nucleic acids, and imaging agents targeted to various organs. PMID:26889958

  2. Structurally ordered Pt–Zn/C series nanoparticles as efficient anode catalysts for formic acid electrooxidation

    SciTech Connect

    Zhu, Jing; Zheng, Xin; Wang, Jie; Wu, Zexing; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wang, Deli

    2015-09-15

    Controlling the size, composition, and structure of bimetallic nanoparticles is of particular interest in the field of electrocatalysts for fuel cells. In the present work, structurally ordered nanoparticles with intermetallic phases of Pt3Zn and PtZn have been successfully synthesized via an impregnation reduction method, followed by post heat-treatment. The Pt3Zn and PtZn ordered intermetallic nanoparticles are well dispersed on a carbon support with ultrasmall mean particle sizes of ~5 nm and ~3 nm in diameter, respectively, which are credited to the evaporation of the zinc element at high temperature. These catalysts are less susceptible to CO poisoning relative to Pt/C and exhibited enhanced catalytic activity and stability toward formic acid electrooxidation. The mass activities of the as-prepared catalysts were approximately 2 to 3 times that of commercial Pt at 0.5 V (vs. RHE). As a result, this facile synthetic strategy is scalable for mass production of catalytic materials.

  3. Structurally ordered Pt–Zn/C series nanoparticles as efficient anode catalysts for formic acid electrooxidation

    DOE PAGES

    Zhu, Jing; Zheng, Xin; Wang, Jie; Wu, Zexing; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wang, Deli

    2015-09-15

    Controlling the size, composition, and structure of bimetallic nanoparticles is of particular interest in the field of electrocatalysts for fuel cells. In the present work, structurally ordered nanoparticles with intermetallic phases of Pt3Zn and PtZn have been successfully synthesized via an impregnation reduction method, followed by post heat-treatment. The Pt3Zn and PtZn ordered intermetallic nanoparticles are well dispersed on a carbon support with ultrasmall mean particle sizes of ~5 nm and ~3 nm in diameter, respectively, which are credited to the evaporation of the zinc element at high temperature. These catalysts are less susceptible to CO poisoning relative to Pt/Cmore » and exhibited enhanced catalytic activity and stability toward formic acid electrooxidation. The mass activities of the as-prepared catalysts were approximately 2 to 3 times that of commercial Pt at 0.5 V (vs. RHE). As a result, this facile synthetic strategy is scalable for mass production of catalytic materials.« less

  4. Cd{sub 1−x}Mn{sub x}Te ultrasmall quantum dots growth in a silicate glass matrix by the fusion method

    SciTech Connect

    Dantas, Noelio Oliveira; Lima Fernandes, Guilherme de; Almeida Silva, Anielle Christine; Baffa, Oswaldo; Gómez, Jorge Antônio

    2014-09-29

    In this study, we synthesized Cd{sub 1−x}Mn{sub x}Te ultrasmall quantum dots (USQDs) in SiO{sub 2}-Na{sub 2}CO{sub 3}-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3} glass system using the fusion method. Growth of these Cd{sub 1−x}Mn{sub x}Te USQDs was confirmed by optical absorption, atomic force microscopy (AFM), magnetic force microscopy (MFM), scanning transmission electron microscopy (TEM), and electron paramagnetic resonance (EPR) measurements. The blueshift of absorption transition with increasing manganese concentration gives evidence of incorporation of manganese ions (Mn{sup 2+}) in CdTe USQDs. AFM, TEM, and MFM confirmed, respectively, the formation of high quality Cd{sub 1−x}Mn{sub x}Te USQDs with uniformly distributed size and magnetic phases. Furthermore, EPR spectra showed six lines associated to the S = 5/2 spin half-filled d-state, characteristic of Mn{sup 2+}, and confirmed that Mn{sup 2+} are located in the sites core and surface of the CdTe USQD. Therefore, synthesis of high quality Cd{sub 1−x}Mn{sub x}Te USQDs may allow the control of optical and magnetic properties.

  5. Small-Angle and Ultrasmall-Angle Neutron Scattering (SANS/USANS) Study of New Albany Shale: A Treatise on Microporosity

    SciTech Connect

    Bahadur, Jitendra; Radlinski, Andrzej P.; Melnichenko, Yuri B.; Mastalerz, Maria; Schimmelmann, Arndt

    2014-12-17

    We applied small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) techniques to study the microstructure of several New Albany shales of different maturity. It has been established that the total porosity decreases with maturity and increases somewhat for post-mature samples. A new method of SANS data analysis was developed, which allows the extraction of information about the size range and number density of micropores from the relatively flat scattering intensity observed in the limit of the large scattering vector Q. Macropores and significant number of mesopores are surface fractals, and their structure can be described in terms of the polydisperse spheres (PDSP) model. The model-independent Porod invariant method was employed to estimate total porosity, and the results were compared with the PDSP model results. It has been demonstrated that independent evaluation of incoherent background is crucial for accurate interpretation of the scattering data in the limit of large Q-values. Moreover, pore volumes estimated by the N2 and CO2 adsorption, as well as via the mercury intrusion technique, have been compared with those measured by SANS/USANS, and possible reasons for the observed discrepancies are discussed.

  6. Small-Angle and Ultrasmall-Angle Neutron Scattering (SANS/USANS) Study of New Albany Shale: A Treatise on Microporosity

    DOE PAGES

    Bahadur, Jitendra; Radlinski, Andrzej P.; Melnichenko, Yuri B.; Mastalerz, Maria; Schimmelmann, Arndt

    2014-12-17

    We applied small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) techniques to study the microstructure of several New Albany shales of different maturity. It has been established that the total porosity decreases with maturity and increases somewhat for post-mature samples. A new method of SANS data analysis was developed, which allows the extraction of information about the size range and number density of micropores from the relatively flat scattering intensity observed in the limit of the large scattering vector Q. Macropores and significant number of mesopores are surface fractals, and their structure can be described in terms of themore » polydisperse spheres (PDSP) model. The model-independent Porod invariant method was employed to estimate total porosity, and the results were compared with the PDSP model results. It has been demonstrated that independent evaluation of incoherent background is crucial for accurate interpretation of the scattering data in the limit of large Q-values. Moreover, pore volumes estimated by the N2 and CO2 adsorption, as well as via the mercury intrusion technique, have been compared with those measured by SANS/USANS, and possible reasons for the observed discrepancies are discussed.« less

  7. Sequential Drug Release and Enhanced Photothermal and Photoacoustic Effect of Hybrid Reduced Graphene Oxide-Loaded Ultrasmall Gold Nanorod Vesicles for Cancer Therapy.

    PubMed

    Song, Jibin; Yang, Xiangyu; Jacobson, Orit; Lin, Lisen; Huang, Peng; Niu, Gang; Ma, Qingjie; Chen, Xiaoyuan

    2015-09-22

    We report a hybrid reduced graphene oxide (rGO)-loaded ultrasmall plasmonic gold nanorod vesicle (rGO-AuNRVe) (∼65 nm in size) with remarkably amplified photoacoustic (PA) performance and photothermal effects. The hybrid vesicle also exhibits a high loading capacity of doxorubicin (DOX), as both the cavity of the vesicle and the large surface area of the encapsulated rGO can be used for loading DOX, making it an excellent drug carrier. The loaded DOX is released sequentially: near-infrared photothermal heating induces DOX release from the vesicular cavity, and an intracellular acidic environment induces DOX release from the rGO surface. Positron emission tomography imaging showed high passive U87MG tumor accumulation of (64)Cu-labeled rGO-AuNRVes (∼9.7% ID/g at 24 h postinjection) and strong PA signal in the tumor region. Single intravenous injection of rGO-AuNRVe-DOX followed by low-power-density 808 nm laser irradiation (0.25 W/cm(2)) revealed effective inhibition of tumor growth due to the combination of chemo- and photothermal therapies. The rGO-AuNRVe-DOX capable of sequential DOX release by laser light and acid environment may have the potential for clinical translation to treat cancer patients with tumors accessible by light. PMID:26308265

  8. Binary cobalt ferrite nanomesh arrays as the advanced binder-free electrode for applications in oxygen evolution reaction and supercapacitors

    NASA Astrophysics Data System (ADS)

    Liu, Li; Zhang, Huijuan; Mu, Yanping; Bai, Yuanjuan; Wang, Yu

    2016-09-01

    The porous CoFe2O4nanomesh arrays are successfully synthesized on nickel foam substrate through a high temperature and pressure hydrothermal method, following by the thermal post-treatment in air. The CoFe2O4 nanomesh arrays own numerous pores and large specific surface area, which is in favor of exposing more active sites. In consideration of the structural preponderances and versatility of the materials, the CoFe2O4 nanomesh arrays have been researched as the binder-free electrode materials for electrocatalysis and supercapacitors. When the CoFe2O4nanomesh arrays on nickel foam (CoFe2O4 NM-As/Ni) directly act as the free-binder catalyst toward catalyzing the oxygen evolution reaction (OER) of electrochemical water splitting, CoFe2O4 NM-As/Ni exhibits an admirable OER property with a low onset potential of 1.47 V(corresponding to the onset overpotential of 240 mV), a minimal overpotential (η10 = 253 mV), a small Tafel slope (44 mV dec-1), large anodic currents and long-term durability for 35 h in alkaline media. In addition, as an electrode of supercapacitors, CoFe2O4 NM-As/Ni obtains a desired specific capacitance (1426 F/g at the current density of 1 A/g), remarkable rate capability (1024 F/g at the current density of 20 A/g) and eminent capacitance retention (92.6% after 3000 cycles). The above results demonstrate the CoFe2O4 NM-As/Ni possesses great potential application in electrocatalysis and supercapacitors.

  9. Magnetic properties of Ga doped cobalt ferrite: Compton scattering study

    NASA Astrophysics Data System (ADS)

    Sharma, Arvind; Sahariya, Jagrati; Mund, H. S.; Itou, M.; Sakurai, Y.; Ahuja, B. L.

    2014-04-01

    We present the spin momentum density of Ga doped CoFe2O4 at 100 K using magnetic Compton scattering. The measurement has been performed using circularly polarized synchrotron radiations of 182.65 keV at SPring8, Japan. The experimental profile is decomposed into its constituent profile to determine the spin moment at individual sites. Co atom has the maximum contribution (about 58%) in the total spin moment of the doped CoFe2O4.

  10. The structure and dynamics of polymer nanocomposites containing anisotropic nanoparticles

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Chun; Ohno, Kohji; Clarke, Nigel; Winey, Karen; Composto, Russell; Hore, Michael

    2014-03-01

    The tracer diffusion of deuterated polystyrene (dPS; 49-532 kg/mol) is measured in polystyrene (PS: 270 kg/mol) nanocomposites containing PS-grafted (132 kg/mol) anisotropic nanoparticles (NP). The NP's are small aggregates containing iron oxide spheres (5nm). These NP's uniformly disperse in PS up to 100% loading. The structure of the polymer nanocomposites is probed using (ultra)small angle x-ray scattering (USAXS,SAXS). Peaks shift to high Q region with increasing NP loadings, indicating a decrease in spacing between particles. The interparticle distance for the pure NP case is 30nm, consistent with TEM, and a brush thickness of 15nm. The brush profile is also measured using SANS. The reduced tracer diffusion coefficient initially decreases as NP loadings increase and then reaches a minimum (35% reduction) near 0.25 vol% (core) for all dPS. With a further increase in NP loading, diffusion recovers to 90% of the unfilled case. Penetration of the tracer (i.e., wetting) into the brush will affect the effective interparticle distance. Diffusion of dPS (1866 kg/mol) will be examined to determine if the dry brush case influences the recovery at high loading. These experiments demonstrate that polymer brushes grafted to anisotropic nano particles can affect the tracer diffusion pathway and indicate that diffusion models should incorporate the interfacial structure between brush and matrix.

  11. Advanced multimodal nanoparticles delay tumor progression with clinical radiation therapy.

    PubMed

    Detappe, Alexandre; Kunjachan, Sijumon; Sancey, Lucie; Motto-Ros, Vincent; Biancur, Douglas; Drane, Pascal; Guieze, Romain; Makrigiorgos, G Mike; Tillement, Olivier; Langer, Robert; Berbeco, Ross

    2016-09-28

    Radiation therapy is a major treatment regimen for more than 50% of cancer patients. The collateral damage induced on healthy tissues during radiation and the minimal therapeutic effect on the organ-of-interest (target) is a major clinical concern. Ultra-small, renal clearable, silica based gadolinium chelated nanoparticles (SiGdNP) provide simultaneous MR contrast and radiation dose enhancement. The high atomic number of gadolinium provides a large photoelectric cross-section for increased photon interaction, even for high-energy clinical radiation beams. Imaging and therapy functionality of SiGdNP were tested in cynomolgus monkeys and pancreatic tumor-bearing mice models, respectively. A significant improvement in tumor cell damage (double strand DNA breaks), growth suppression, and overall survival under clinical radiation therapy conditions were observed in a human pancreatic xenograft model. For the first time, safe systemic administration and systematic renal clearance was demonstrated in both tested species. These findings strongly support the translational potential of SiGdNP for MR-guided radiation therapy in cancer treatment. PMID:27423325

  12. Conjugation of iron oxide nanoparticles with RGD-modified dendrimers for targeted tumor MR imaging.

    PubMed

    Yang, Jia; Luo, Yu; Xu, Yanhong; Li, Jingchao; Zhang, Zaixian; Wang, Han; Shen, Mingwu; Shi, Xiangyang; Zhang, Guixiang

    2015-03-11

    This article reports a new approach for the synthesis of ultrasmall iron oxide nanoparticles (NPs) conjugated with Arg-Gly-Asp (RGD)-modified dendrimers (G5.NHAc-RGD-Fe3O4 NPs) as a platform for targeted magnetic resonance (MR) imaging of C6 glioma cells. Ultrasmall Fe3O4 NPs synthesized via a solvothermal route were conjugated with RGD peptide-modified generation-5 poly(amidoamine) dendrimers (G5.NH2-RGD). The final G5.NHAc-RGD-Fe3O4 NPs were formed following the acetylation of the remaining dendrimer terminal amines. The as-prepared multifunctional Fe3O4 NPs were characterized using various techniques. The results of a cell viability assay, cell morphological observation, and hemolysis assay indicated that the G5.NHAc-RGD-Fe3O4 NPs exhibit excellent cytocompatibility and hemocompatibility over the studied concentration range. In addition, RGD conjugated onto the Fe3O4 NPs allows for the efficient targeting of the particles to C6 cells that overexpress αvβ3 receptors, which was confirmed via in vitro cell MR imaging and cellular uptake. Finally, the G5.NHAc-RGD-Fe3O4 NPs were used in the targeted MR imaging of C6 glioma cells in mice. The results obtained from the current study indicate that the developed G5.NHAc-RGD-Fe3O4 NPs offer significant potential for use as contrast agents in the targeted MR imaging of different types of tumors.

  13. An injectable acellular matrix scaffold with absorbable permeable nanoparticles improves the therapeutic effects of docetaxel on glioblastoma.

    PubMed

    Xu, He-Lin; Mao, Kai-Li; Lu, Cui-Tao; Fan, Zi-Liang; Yang, Jing-Jing; Xu, Jie; Chen, Pian-Pian; ZhuGe, De-Li; Shen, Bi-Xin; Jin, Bing-Hui; Xiao, Jian; Zhao, Ying-Zheng

    2016-11-01

    Intratumoral drug delivery (IT) is an inherently appealing approach for concentrating toxic chemotherapies at the site of action. However, for most chemotherapies, poor tumor penetration and short retention at the administration site limit their anti-tumor effects. In this work, we describe permeable nanoparticles (NPs) prepared with a novel amphiphilic polymer, RRR-α-tocopheryl succinate-grafted-ε-polylysine conjugate (VES-g-ε-PLL). The nanoparticles (NPs) of VES-g-ε-PLL exhibited an ultra-small hydrodynamic diameter (20.8 nm) and positive zeta potential (20.6 mV), which facilitate strong glioma spheroid penetration ability in vitro. Additionally, the hydrophobic model drug docetaxel (DTX) could be effectively encapsulated in the nanoparticles with 3.99% drug loading and 73.37% encapsulation efficiency. To prolong the retention time of DTX-loaded nanoparticles (DTX-NPs) in the tumor, intact decellularized brain extracellular matrix (dBECM) derived from healthy rats was used as a drug depot to adsorb the ultra-small DTX-NPs. The intact DTX-NPs-adsorbing dBECM scaffold was further homogenized into an injectable DTX-NPs-dBECM suspension for intratumoral administration. The DTX-NPs-dBECM suspension exhibited slower DTX release than naked DTX-NPs without compromising the tumor penetration ability of DTX-NPs. An antitumor study showed that the DTX-NPs-dBECM suspension exhibited more powerful in vitro inhibition of tumor spheroid growth than free DTX solution or DTX-NPs. Due to strong tumor penetration ability and prolonged retention, DTX-NPs-dBECM led to complete suppression of glioma growth in vivo at 28 days after treatment. The therapeutic mechanism was due to enhanced proliferation inhibition and apoptosis of tumor cells and angiogenesis inhibition of glioma after treatment with DTX-NPs-dBECM. Finally, the safety of DTX-NPs-dBECM at the therapeutic dose was demonstrated via pathological HE assay from heart, liver, spleen, lung and kidney tissues. In

  14. Detection of lymph node metastases with ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance imaging in oesophageal cancer: a feasibility study

    PubMed Central

    van der Jagt, E.J.; van Westreenen, H.L.; van Dullemen, H.M.; Kappert, P.; Groen, H.; Sietsma, J.; Oudkerk, M.; Plukker, J.Th.M.; van Dam, G.M.

    2009-01-01

    Abstract Aim: In this feasibility study we investigated whether magnetic resonance imaging (MRI) with ultrasmall superparamagnetic iron oxide (USPIO) can be used to identify regional and distant lymph nodes, including mediastinal and celiac lymph node metastases in patients with oesophageal cancer. Patients and methods: Ten patients with a potentially curative resectable cancer of the oesophagus were eligible for this study. All patients included in the study had positive lymph nodes on conventional staging (including endoscopic ultrasound, computed tomography and fluorodeoxyglucose-positron emission tomography). Nine patients underwent MRI + USPIO before surgery. Results were restricted to those patients who had both MRI + USPIO and histological examination. Results were compared with conventional staging and histopathologic findings. Results: One patient was excluded due to expired study time. Five out of 9 patients underwent an exploration; in 1 patient prior to surgery MRI + USPIO diagnosed liver metastases and in 3 patients an oesophageal resection was performed. USPIO uptake in mediastinal lymph nodes was seen in 6 out of 9 patients; in 3 patients non-malignant nodes were not visible. In total, 9 lymph node stations (of 6 patients) were separately analysed; 7 lymph node stations were assessed as positive (N1) on MRI+USPIO compared with 9 by conventional staging. According to histology findings, there was one false-positive and one false-negative result in MRI + USPIO. Also, conventional staging modalities had one false-positive and one false-negative result. MRI + USPIO had surplus value in one patient. Not all lymph node stations could be compared due to unforeseen explorations. No adverse effects occurred after USPIO infusion. Conclusion: MRI+USPIO identified the majority of mediastinal and celiac (suspect) lymph nodes in 9 patients with oesophageal cancer. MRI+USPIO could have an additional value in loco-regional staging; however, more

  15. Ultra-small superparamagnetic iron oxide mediated magnetic hyperthermia in treatment of neck lymph node metastasis in rabbit pyriform sinus VX2 carcinoma.

    PubMed

    Wang, Peng; Xie, Xiaofeng; Wang, Jian; Shi, Yuan; Shen, Na; Huang, Xinsheng

    2015-09-01

    Lymph node metastasis of rabbit VX2 pyriform sinus carcinoma can be enhanced by MR scanning after injecting ultra-small superparamagnetic iron oxide (USPIO) into the submucosa beside the tumor. The metastasis lymph node which fit in with the diagnostic criteria will be placed into the alternating magnetic field after MR scanning. Then, magnetic particles can be heated to the effective therapeutic temperature. And it evaluates the possibility of diagnosis together with therapy in cervical metastasis of pyriform sinus carcinoma. Twenty rabbits bearing VX2 tumor in pyriform sinuses were randomly divided into hyperthermia group and control group after USPIO MR scanning; each group contained 10 rabbits. The hyperthermia for the experimental group was conducted by the alternating magnetic field. After hyperthermia, the detection of apoptosis for the two groups was tested by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL), transmission electron microscopy (TEM), and the expression of Bcl-2 and Bax evaluated by immunohistochemical analysis. The apoptosis rate detected by TUNEL in hyperthermia group was 100 %, while the control group was only 20 % (p < 0.05). TEM observation showed that cell chromatin condensation and clumping, condensed cytoplasm, endoplasmic reticulum membrane fusion with loose change, and the formation of a bubble could be seen in the hyperthermia group. However, the control group showed a more complete cytoplasm and nucleus. Bcl-2 protein expression in the hyperthermia group was lower than the control group, and Bax protein expression in hyperthermia group was higher (p < 0.05). USPIO indirect lymphography could localize the metastatic lymph nodes for hyperthermia. And it could make the metastatic cervical lymph nodes apoptosis when placed into the alternating magnetic field. PMID:25971580

  16. In-Situ Monitoring of the Microstructure of TATB-based Explosive Formulations During Temperature Cycling using Ultra-small Angle X-ray Scattering

    SciTech Connect

    Willey, T M; Hoffman, D M; van Buuren, T; Lauderbach, L; Ilavsky, J; Gee, R H; Maiti, A; Overturf, G; Fried, L

    2008-02-06

    TATB (1,3,5 triamino-2,4,6-trinitrobenzene), an extremely insensitive explosive, is used both in plastic-bonded explosives (PBXs) and as an ultra-fine pressed powder (UFTATB). With both PBXs and UFTATB, an irreversible expansion occurs with temperature cycling known as ratchet growth. In TATB-based explosives using Kel-F 800 as binder (LX-17 and PBX-9502), additional voids, sizes hundreds of nanometers to a few microns account for much of the volume expansion caused by temperature cycling. These voids are in the predicted size regime for hot-spot formation during ignition and detonation, and thus an experimental measure of these voids is important feedback for hot-spot theory and for determining the relationship between void size distributions and detonation properties. Also, understanding the mechanism of ratchet growth allows future choice of explosive/binder mixtures to minimize these types of changes to explosives, further extending PBX shelf life. This paper presents the void size distributions of LX-17, UFTATB, and PBXs using commercially available Cytop M, Cytop A, and Hyflon AD60 binders during temperature cycling between -55 C and 70 C. These void size distributions are derived from ultra-small angle x-ray scattering (USAXS), a technique sensitive to structures from about 10 nm to about 2 mm. Structures with these sizes do not appreciably change in UFTATB, indicating voids or cracks larger than a few microns appear in UFTATB during temperature cycling. Compared to Kel-F 800 binders, Cytop M and Cytop A show relatively small increases in void volume from 0.9% to 1.3% and 0.6% to 1.1%, respectively, while Hyflon fails to prevent irreversible volume expansion (1.2% to 4.6%). Computational mesoscale models of ratchet growth and binder wetting and adhesion properties point to mechanisms of ratchet growth, and are discussed in combination with the experimental results.

  17. Synthesis and characterization of PEGylated Gd2O3 nanoparticles for MRI contrast enhancement.

    PubMed

    Ahrén, Maria; Selegård, Linnéa; Klasson, Anna; Söderlind, Fredrik; Abrikossova, Natalia; Skoglund, Caroline; Bengtsson, Torbjörn; Engström, Maria; Käll, Per-Olov; Uvdal, Kajsa

    2010-04-20

    Recently, much attention has been given to the development of biofunctionalized nanoparticles with magnetic properties for novel biomedical imaging. Guided, smart, targeting nanoparticulate magnetic resonance imaging (MRI) contrast agents inducing high MRI signal will be valuable tools for future tissue specific imaging and investigation of molecular and cellular events. In this study, we report a new design of functionalized ultrasmall rare earth based nanoparticles to be used as a positive contrast agent in MRI. The relaxivity is compared to commercially available Gd based chelates. The synthesis, PEGylation, and dialysis of small (3-5 nm) gadolinium oxide (DEG-Gd(2)O(3)) nanoparticles are presented. The chemical and physical properties of the nanomaterial were investigated with Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and dynamic light scattering. Neutrophil activation after exposure to this nanomaterial was studied by means of fluorescence microscopy. The proton relaxation times as a function of dialysis time and functionalization were measured at 1.5 T. A capping procedure introducing stabilizing properties was designed and verified, and the dialysis effects were evaluated. A higher proton relaxivity was obtained for as-synthesized diethylene glycol (DEG)-Gd(2)O(3) nanoparticles compared to commercial Gd-DTPA. A slight decrease of the relaxivity for as-synthesized DEG-Gd(2)O(3) nanoparticles as a function of dialysis time was observed. The results for functionalized nanoparticles showed a considerable relaxivity increase for particles dialyzed extensively with r(1) and r(2) values approximately 4 times the corresponding values for Gd-DTPA. The microscopy study showed that PEGylated nanoparticles do not activate neutrophils in contrast to uncapped Gd(2)O(3). Finally, the nanoparticles are equipped with Rhodamine to show that our PEGylated nanoparticles are available for further coupling

  18. Magnetic resonance imaging of folic acid-coated magnetite nanoparticles reflects tissue biodistribution of long-acting antiretroviral therapy

    PubMed Central

    Li, Tianyuzi; Gendelman, Howard E; Zhang, Gang; Puligujja, Pavan; McMillan, JoEllyn M; Bronich, Tatiana K; Edagwa, Benson; Liu, Xin-Ming; Boska, Michael D

    2015-01-01

    Regimen adherence, systemic toxicities, and limited drug penetrance to viral reservoirs are obstacles limiting the effectiveness of antiretroviral therapy (ART). Our laboratory’s development of the monocyte-macrophage-targeted long-acting nanoformulated ART (nanoART) carriage provides a novel opportunity to simplify drug-dosing regimens. Progress has nonetheless been slowed by cumbersome, but required, pharmacokinetic (PK), pharmacodynamics, and biodistribution testing. To this end, we developed a small magnetite ART (SMART) nanoparticle platform to assess antiretroviral drug tissue biodistribution and PK using magnetic resonance imaging (MRI) scans. Herein, we have taken this technique a significant step further by determining nanoART PK with folic acid (FA) decorated magnetite (ultrasmall superparamagnetic iron oxide [USPIO]) particles and by using SMART particles. FA nanoparticles enhanced the entry and particle retention to the reticuloendothelial system over nondecorated polymers after systemic administration into mice. These data were seen by MRI testing and validated by comparison with SMART particles and direct evaluation of tissue drug levels after nanoART. The development of alendronate (ALN)-coated magnetite thus serves as a rapid initial screen for the ability of targeting ligands to enhance nanoparticle-antiretroviral drug biodistribution, underscoring the value of decorated magnetite particles as a theranostic tool for improved drug delivery. PMID:26082630

  19. Magnetic resonance imaging of folic acid-coated magnetite nanoparticles reflects tissue biodistribution of long-acting antiretroviral therapy.

    PubMed

    Li, Tianyuzi; Gendelman, Howard E; Zhang, Gang; Puligujja, Pavan; McMillan, JoEllyn M; Bronich, Tatiana K; Edagwa, Benson; Liu, Xin-Ming; Boska, Michael D

    2015-01-01

    Regimen adherence, systemic toxicities, and limited drug penetrance to viral reservoirs are obstacles limiting the effectiveness of antiretroviral therapy (ART). Our laboratory's development of the monocyte-macrophage-targeted long-acting nanoformulated ART (nanoART) carriage provides a novel opportunity to simplify drug-dosing regimens. Progress has nonetheless been slowed by cumbersome, but required, pharmacokinetic (PK), pharmacodynamics, and biodistribution testing. To this end, we developed a small magnetite ART (SMART) nanoparticle platform to assess antiretroviral drug tissue biodistribution and PK using magnetic resonance imaging (MRI) scans. Herein, we have taken this technique a significant step further by determining nanoART PK with folic acid (FA) decorated magnetite (ultrasmall superparamagnetic iron oxide [USPIO]) particles and by using SMART particles. FA nanoparticles enhanced the entry and particle retention to the reticuloendothelial system over nondecorated polymers after systemic administration into mice. These data were seen by MRI testing and validated by comparison with SMART particles and direct evaluation of tissue drug levels after nanoART. The development of alendronate (ALN)-coated magnetite thus serves as a rapid initial screen for the ability of targeting ligands to enhance nanoparticle-antiretroviral drug biodistribution, underscoring the value of decorated magnetite particles as a theranostic tool for improved drug delivery. PMID:26082630

  20. Tuning the observability of surface plasmon in silica-gold raspberry shaped nanoparticles using cuprous oxide shell.

    PubMed

    Tyagi, Himanshu; Mohapatra, Jeotikanta; Kushwaha, Ajay; Aslam, Mohammed

    2013-12-11

    A raspberry shaped silica-gold nanoparticle system has been coated with a cuprous oxide shell using a simple wet chemical approach. The optical properties of such particles depend on thin dielectric shell material, and we calculate far-field scattering and extinction of cuprous oxide coated silica-gold composite. In accordance with our theoretical findings, for ultrasmall gold nanoparticles (AuNPs < 5 nm) attached over silica, the localized surface plasmon resonance (LSPR) peak is completely suppressed after Cu2O coating. The cloaking (nonobservability) of the LSPR peak in extinction spectra has been explained via calculation of contribution from absorbance (<10%) and scattering (>90%) in the composite nanostructure. For larger particles (>5 nm), the traditional red-shift of the plasmon peak (from 532 to 588 nm) is still significant due to the large dielectric constant (approx. 8.0 @ 600 nm) of cuprous oxide (Cu2O) coating. A complete and controlled suppression of LSPR in small sized gold nanoparticles due to high dielectric refractory oxide shell could play a significant role in plasmon derived applications.

  1. Targeting B16 tumors in vivo with peptide-conjugated gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Poon, Wilson; Zhang, Xuan; Bekah, Devesh; Teodoro, Jose G.; Nadeau, Jay L.

    2015-07-01

    This study examines the effects of polyethylene glycol (PEG) and peptide conjugation on the biodistribution of ultrasmall (2.7 nm) gold nanoparticles in mice bearing B16 melanoma allografts. Nanoparticles were delivered intravenously, and biodistribution was measured at specific timepoints by organ digestion and inductively coupled plasma mass spectrometry. All major organs were examined. Two peptides were tested: the cyclic RGD peptide (cRGD, which targets integrins); and a recently described peptide derived from the myxoma virus. We found the greatest specific tumor delivery using the myxoma peptide, with or without PEGylation. Un-PEGylated cRGD performed poorly, but PEGylated RGD showed a significant transient collection in the tumor. Liver and kidney were the primary targets of all constructs. None of the particles were able to cross the blood-brain barrier. Although it was able to deliver Au to B16 cells, the myxoma peptide did not show any cytotoxic activity against these cells, in contrast to previous reports. These results indicate that the effect of passive targeting by PEGylation and active targeting by peptides can be independent or combined, and that they should be evaluated on a case-by-case basis when designing new nanosystems for targeted therapies. Both myxoma peptide and cRGD should be considered for specific targeting to melanoma, but a thorough investigation of the cytotoxicity of the myxoma peptide to different cell lines remains to be performed.

  2. Sb nanoparticles encapsulated into porous carbon matrixes for high-performance lithium-ion battery anodes

    NASA Astrophysics Data System (ADS)

    Yi, Zheng; Han, Qigang; Zan, Ping; Wu, Yaoming; Cheng, Yong; Wang, Limin

    2016-11-01

    A novel Sb/C polyhedra composite is successfully fabricated by a galvanic replacement reaction technique using metal organic frameworks as templates. In this composite, the ultrasmall Sb nanoparticles with an average size of 15 nm are homogeneously encapsulated into the carbon matrixes, forming a hierarchical porous structure with nanosized building blocks. Used as an anode material for lithium ion batteries, this composite exhibits high lithium storage capacities, excellent rate capability and superior cycle stability, higher than many reported results. Notably, a discharge capacity of 565 mAh g-1 at a current density of 0.2 A g-1 is delivered after 100 repeated cycles. Even at a high current density of 1 A g-1, a discharge capacity of 400.5 mAh g-1 is also maintained after 500 cycles. Such superior cycling stability and rate discharge performance of the designed Sb/C composite can be attributed to the synergistic effect between Sb nanoparticles and the porous carbon matrixes.

  3. Pulse-driven micro gas sensor fitted with clustered Pd/SnO2 nanoparticles.

    PubMed

    Suematsu, Koichi; Shin, Yuka; Ma, Nan; Oyama, Tokiharu; Sasaki, Miyuki; Yuasa, Masayoshi; Kida, Tetsuya; Shimanoe, Kengo

    2015-08-18

    Real-time monitoring of specific gas concentrations with a compact and portable gas sensing device is required to sense potential health risk and danger from toxic gases. For such purposes, we developed an ultrasmall gas sensor device, where a micro sensing film was deposited on a micro heater integrated with electrodes fabricated by the microelectromechanical system (MEMS) technology. The developed device was operated in a pulse-heating mode to significantly reduce the heater power consumption and make the device battery-driven and portable. Using clustered Pd/SnO2 nanoparticles, we succeeded in introducing mesopores ranging from 10 to 30 nm in the micro gas sensing film (area: ϕ 150 μm) to detect large volatile organic compounds (VOCs). The micro sensor showed quick, stable, and high sensor responses to toluene at ppm (parts per million) concentrations at 300 °C even by operating the micro heater in a pulse-heating mode where switch-on and -off cycles were repeated at one-second intervals. The high performance of the micro sensor should result from the creation of efficient diffusion paths decorated with Pd sensitizers by using the clustered Pd/SnO2 nanoparticles. Hence we demonstrate that our pulse-driven micro sensor using nanostructured oxide materials holds promise as a battery-operable, portable gas sensing device. PMID:26196499

  4. Stir bar sorptive-dispersive microextraction mediated by magnetic nanoparticles-nylon 6 composite for the extraction of hydrophilic organic compounds in aqueous media.

    PubMed

    Benedé, Juan L; Chisvert, Alberto; Giokas, Dimosthenis L; Salvador, Amparo

    2016-07-01

    A new and sensitive analytical method based on the recently developed approach termed stir bar-sorptive dispersive microextraction (SBSDME) using a magnetic CoFe2O4@SiO2-nylon 6 composite as sorbent material is presented for the extraction of hydrophilic organic compounds. The simultaneous determination of four hydrophilic UV filters in environmental water samples has been chosen as a model analytical application due to the increasing awareness regarding the occurrence of sunscreen residuals in natural waters. The developed SBSDME approach combines the principles and benefits of stir bar sorptive extraction (SBSE) and dispersive solid phase extraction (DSPE) but allows for lower extraction time and easier post-extraction treatment. Moreover, most importantly, it enables the use of new magnetic materials that affords higher versatility and can be tailored to the needs of the analysis. The main experimental parameters involved in the SBSDME process (i.e. composite amount, extraction time, pH, ionic strength, desorption solvent and desorption time) were evaluated to provide the best enrichment factors. Under the optimized conditions, the method was successfully validated showing good linearity, enrichment factors between 105 and 145 depending on the analyte, limits of detection and quantification in the low ng mL(-1) range (1.6-2.9 ng mL(-1) and 5.4-9.6 ng mL(-1), respectively) and good intra- and inter-day repeatability (RSD < 13%). The developed method was applied to the analysis of water samples of different origin (sea, river and swimming pool). Relative recovery values ranged between 90 and 115%, thus showing that the matrices under consideration do not affect the extraction process.

  5. Stir bar sorptive-dispersive microextraction mediated by magnetic nanoparticles-nylon 6 composite for the extraction of hydrophilic organic compounds in aqueous media.

    PubMed

    Benedé, Juan L; Chisvert, Alberto; Giokas, Dimosthenis L; Salvador, Amparo

    2016-07-01

    A new and sensitive analytical method based on the recently developed approach termed stir bar-sorptive dispersive microextraction (SBSDME) using a magnetic CoFe2O4@SiO2-nylon 6 composite as sorbent material is presented for the extraction of hydrophilic organic compounds. The simultaneous determination of four hydrophilic UV filters in environmental water samples has been chosen as a model analytical application due to the increasing awareness regarding the occurrence of sunscreen residuals in natural waters. The developed SBSDME approach combines the principles and benefits of stir bar sorptive extraction (SBSE) and dispersive solid phase extraction (DSPE) but allows for lower extraction time and easier post-extraction treatment. Moreover, most importantly, it enables the use of new magnetic materials that affords higher versatility and can be tailored to the needs of the analysis. The main experimental parameters involved in the SBSDME process (i.e. composite amount, extraction time, pH, ionic strength, desorption solvent and desorption time) were evaluated to provide the best enrichment factors. Under the optimized conditions, the method was successfully validated showing good linearity, enrichment factors between 105 and 145 depending on the analyte, limits of detection and quantification in the low ng mL(-1) range (1.6-2.9 ng mL(-1) and 5.4-9.6 ng mL(-1), respectively) and good intra- and inter-day repeatability (RSD < 13%). The developed method was applied to the analysis of water samples of different origin (sea, river and swimming pool). Relative recovery values ranged between 90 and 115%, thus showing that the matrices under consideration do not affect the extraction process. PMID:27216394

  6. Polarization of Magnetic Dipole Emission and Spinning Dust Emission from Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Hoang, Thiem; Lazarian, Alex

    2016-04-01

    Magnetic dipole emission (MDE) from interstellar magnetic nanoparticles is potentially an important Galactic foreground in the microwave frequencies, and its polarization level may pose great challenges for achieving reliable measurements of cosmic microwave background B-mode signal. To obtain realistic predictions for the polarization of MDE, we first compute the degree of alignment of big silicate grains incorporated with magnetic inclusions. We find that thermally rotating big grains with magnetic inclusions are weakly aligned and can achieve alignment saturation when the magnetic alignment rate becomes much faster than the rotational damping rate. We then compute the degree of alignment for free-flying magnetic nanoparticles, taking into account various interaction processes of grains with the ambient gas and radiation field, including neutral collisions, ion collisions, and infrared emission. We find that the rotational damping by infrared emission can significantly decrease the degree of alignment of small particles from the saturation level, whereas the excitation by ion collisions can enhance the alignment of ultrasmall particles. Using the computed degrees of alignment, we predict the polarization level of MDE from free-flying magnetic nanoparticles to be rather low. Such a polarization level is within the upper limits measured for anomalous microwave emission (AME), which indicates that MDE from free-flying iron particles may not be ruled out as a source of AME. We also quantify rotational emission from free-flying iron nanoparticles with permanent magnetic moments and find that its emissivity is about one order of magnitude lower than that from spinning polycyclic aromatic hydrocarbons.

  7. Nano electrochemical reactors of Fe2O3 nanoparticles embedded in shells of nitrogen-doped hollow carbon spheres as high-performance anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zheng, Fangcai; He, Mengni; Yang, Yang; Chen, Qianwang

    2015-02-01

    Iron oxides are extensively investigated as anode materials for lithium-ion batteries (LIBs) because of their large specific capacities. However, they undergo huge volume changes during cycling that result in anode pulverization and loss of electrical connectivity. As a result, the capacity retention of the iron oxide anodes is poor and should be improved for commercial applications. Herein, we report the preparation of ultrasmall Fe2O3 nanoparticles embedded in nitrogen-doped hollow carbon sphere shells (Fe2O3@N-C) by the direct pyrolysis of Fe-based zeolitic imidazolate frameworks (Fe-ZIF) at 620 °C in air. As an anode material for LIBs, the capacity retained was 1573 mA h g-1 after 50 cycles at a current density of 0.1 C (1 C = 1000 mA g-1). Even undergoing the high-rate capability test twice, it can still deliver a remarkably reversible and stable capacity of 1142 mA h g-1 after 100 cycles at a current density of 1 C. The excellent electrochemical performance is attributed to the unique structure of ultrasmall Fe2O3 nanoparticles uniformly distributed in the shell of nitrogen-doped carbon spheres, which simultaneously solve the major problems of pulverization, facilitate rapid electrochemical kinetics, and effectively avoid the aggregation of Fe2O3 nanoparticles during de/lithiation. The novel method developed in this work for the synthesis of functional hybrid materials can be extended to the preparation of various MOFs-derived functional nanocomposites owing to the versatility of links and metal centers in MOFs.Iron oxides are extensively investigated as anode materials for lithium-ion batteries (LIBs) because of their large specific capacities. However, they undergo huge volume changes during cycling that result in anode pulverization and loss of electrical connectivity. As a result, the capacity retention of the iron oxide anodes is poor and should be improved for commercial applications. Herein, we report the preparation of ultrasmall Fe2O3 nanoparticles

  8. Edible oil structures at low and intermediate concentrations. II. Ultra-small angle X-ray scattering of in situ tristearin solids in triolein

    NASA Astrophysics Data System (ADS)

    Peyronel, Fernanda; Ilavsky, Jan; Mazzanti, Gianfranco; Marangoni, Alejandro G.; Pink, David A.

    2013-12-01

    Ultra-small angle X-ray scattering has been used for the first time to elucidate, in situ, the aggregation structure of a model edible oil system. The three-dimensional nano- to micro-structure of tristearin solid particles in triolein solvent was investigated using 5, 10, 15, and 20% solids. Three different sample preparation procedures were investigated: two slow cooling rates of 0.5°/min, case 1 (22 days of storage at room temperature) and case 2 (no storage), and one fast cooling of 30°/min, case 3 (no storage). The length scale investigated, by using the Bonse-Hart camera at beamline ID-15D at the Advanced Photon Source, Argonne National Laboratory, covered the range from 300 Å to 10 μm. The unified fit and the Guinier-Porod models in the Irena software were used to fit the data. The former was used to fit 3 structural levels. Level 1 structures showed that the primary scatterers were essentially 2-dimensional objects for the three cases. The scatterers possessed lateral dimensions between 1000 and 4300 Å. This is consistent with the sizes of crystalline nanoplatelets present which were observed using cryo-TEM. Level 2 structures were aggregates possessing radii of gyration, Rg2 between 1800 Å and 12000 Å and fractal dimensions of either D2=1 for case 3 or 1.8≤D2≤2.1 for case 1 and case 2. D2 = 1 is consistent with unaggregated 1-dimensional objects. 1.8 ≤ D2 ≤ 2.1 is consistent with these 1-dimensional objects (below) forming structures characteristic of diffusion or reaction limited cluster-cluster aggregation. Level 3 structures showed that the spatial distribution of the level 2 structures was uniform, on the average, for case 1, with fractal dimension D3≈3 while for case 2 and case 3 the fractal dimension was D3≈2.2, which suggested that the large-scale distribution had not come to equilibrium. The Guinier-Porod model showed that the structures giving rise to the aggregates with a fractal dimension given by D2 in the unified fit level 2

  9. Detection of Target Biomolecules by Magnetic Reporting Using Rod-Like Nanosensors

    NASA Astrophysics Data System (ADS)

    Guertin, R. P.; Goldberg, E.; Harrah, T. P.; Sonkusale, S.; Park, K.; Sun, S.; Oh, J. I.; Naughton, M.

    2008-03-01

    We describe the ongoing development of a device to assay a variety of cellular, viral and molecular targets by measuring the increase of the Brownian relaxation time, τ, in solution of magnetically-tagged nanoscale detectors. The shift shows as a frequency reduction of the peak of the complex magnetic susceptibility, χ(φ)''. Measurements of χ(φ)'' with 12 nm monodisperse nanoparticles of CoFe2O4 coated with polyethelyne glycol reveal spectra with the narrowest lines yet reported. Thin avidin coating of these particles reveals small shifts in χ(φ)''. Bacteriophage T4 tail fibers, engineered to specific lengths (30-150 nm), were employed as the platform for magnetic nanoparticle attachment and at the other end for an inserted target peptide epitope. Attachment of the nanoparticles to bacteriophage T4 tail fibers was successful, though no detectable shifts in χ(φ)'' were detected due to weak attachment. The advantages associated with non-spherical geometry detectors will be discussed, as will preliminary measurements with rare earth oxide magnetic nanoparticles. Progress on miniaturization and low power requirements of the electronic detection system will be reported. Supported by NERCE/BEID (NIAID).

  10. A comprehensive overview on the structure and comparison of magnetic properties of nanocrystalline synthesized by a thermal treatment method

    NASA Astrophysics Data System (ADS)

    Naseri, Mahmoud Goodarz; Halimah, M. K.; Dehzangi, Arash; Kamalianfar, Ahmad; Saion, Elias B.; Majlis, Burhanuddin Y.

    2014-03-01

    This study reports the simple synthesis of MFe2O4 (where M=Zn, Mn and Co) nanostructures by a 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 pyrolytic behaviors of the polymeric precursor were analyzed by use of simultaneous thermo-gravimetry analyses (TGA) and derivative thermo-gravimetry (DTG) analyses. The characterization studies were conducted by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of metal oxide bands for all the calcined samples. Magnetic properties were demonstrated by a vibrating sample magnetometer (VSM), which displayed that the calcined samples exhibited different types of magnetic behavior. The present study also substantiated that magnetic properties of ferrite nanoparticles prepared by the thermal treatment method, from viewing microstructures of them, can be explained as the results of the two important factors: cation distribution and impurity phase of α-Fe2O3. These two factors are subcategory of the preparation method which is related to macrostructure of ferrite. Electron paramagnetic resonance (EPR) spectroscopy showed the existence of unpaired electrons ZnFe2O4 and MnFe2O4 nanoparticles while it did not exhibit resonance signal for CoFe2O4 nanoparticles.

  11. X-ray absorption spectroscopy on magnetic nanoscale systems for modern applications

    NASA Astrophysics Data System (ADS)

    Schmitz-Antoniak, Carolin

    2015-06-01

    X-ray absorption spectroscopy facilitated by state-of-the-art synchrotron radiation technology is presented as a powerful tool to study nanoscale systems, in particular revealing their static element-specific magnetic and electronic properties on a microscopic level. A survey is given on the properties of nanoparticles, nanocomposites and thin films covering a broad range of possible applications. It ranges from the ageing effects of iron oxide nanoparticles in dispersion for biomedical applications to the characterisation on a microscopic level of nanoscale systems for data storage devices. In this respect, new concepts for electrically addressable magnetic data storage devices are highlighted by characterising the coupling in a BaTiO3/CoFe2O4 nanocomposite as prototypical model system. But classical magnetically addressable devices are also discussed on the basis of tailoring the magnetic properties of self-assembled ensembles of FePt nanoparticles for data storage and the high-moment material Fe/Cr/Gd for write heads. For the latter cases, the importance is emphasised of combining experimental approaches in x-ray absorption spectroscopy with density functional theory to gain a more fundamental understanding.

  12. Edible oil structures at low and intermediate concentrations. II. Ultra-small angle X-ray scattering of in situ tristearin solids in triolein

    SciTech Connect

    Peyronel, Fernanda; Marangoni, Alejandro G.; Ilavsky, Jan; Mazzanti, Gianfranco; Pink, David A.

    2013-12-21

    Ultra-small angle X-ray scattering has been used for the first time to elucidate, in situ, the aggregation structure of a model edible oil system. The three-dimensional nano- to micro-structure of tristearin solid particles in triolein solvent was investigated using 5, 10, 15, and 20% solids. Three different sample preparation procedures were investigated: two slow cooling rates of 0.5°/min, case 1 (22 days of storage at room temperature) and case 2 (no storage), and one fast cooling of 30°/min, case 3 (no storage). The length scale investigated, by using the Bonse-Hart camera at beamline ID-15D at the Advanced Photon Source, Argonne National Laboratory, covered the range from 300 Å to 10 μm. The unified fit and the Guinier-Porod models in the Irena software were used to fit the data. The former was used to fit 3 structural levels. Level 1 structures showed that the primary scatterers were essentially 2-dimensional objects for the three cases. The scatterers possessed lateral dimensions between 1000 and 4300 Å. This is consistent with the sizes of crystalline nanoplatelets present which were observed using cryo-TEM. Level 2 structures were aggregates possessing radii of gyration, R{sub g2} between 1800 Å and 12000 Å and fractal dimensions of either D{sub 2}=1 for case 3 or 1.8≤D{sub 2}≤2.1 for case 1 and case 2. D{sub 2} = 1 is consistent with unaggregated 1-dimensional objects. 1.8 ≤ D{sub 2} ≤ 2.1 is consistent with these 1-dimensional objects (below) forming structures characteristic of diffusion or reaction limited cluster-cluster aggregation. Level 3 structures showed that the spatial distribution of the level 2 structures was uniform, on the average, for case 1, with fractal dimension D{sub 3}≈3 while for case 2 and case 3 the fractal dimension was D{sub 3}≈2.2, which suggested that the large-scale distribution had not come to equilibrium. The Guinier-Porod model showed that the structures giving rise to the aggregates

  13. J-aggregates of organic dye molecules complexed with iron oxide nanoparticles for imaging-guided photothermal therapy under 915-nm light.

    PubMed

    Song, Xuejiao; Gong, Hua; Liu, Teng; Cheng, Liang; Wang, Chao; Sun, Xiaoqi; Liang, Chao; Liu, Zhuang

    2014-11-12

    Recently, the development of nano-theranostic agents aiming at imaging guided therapy has received great attention. In this work, a near-infrared (NIR) heptamethine indocyanine dye, IR825, in the presence of cationic polymer, polyallylamine hydrochloride (PAH), forms J-aggregates with red-shifted and significantly enhanced absorbance. After further complexing with ultra-small iron oxide nanoparticles (IONPs) and the followed functionalization with polyethylene glycol (PEG), the obtained IR825@PAH-IONP-PEG composite nanoparticles are highly stable in different physiological media. With a sharp absorbance peak, IR825@PAH-IONP-PEG can serve as an effective photothermal agent under laser irradiation at 915 nm, which appears to be optimal in photothermal therapy application considering its improved tissue penetration compared with 808-nm light and much lower water heating in comparison to 980-nm light. As revealed by magnetic resonance (MR) imaging, those nanoparticles after intravenous injection exhibit high tumor accumulation, which is then harnessed for in vivo photothermal ablation of tumors, achieving excellent therapeutic efficacy in a mouse tumor model. This study demonstrates for the first time that J-aggregates of organic dye molecules are an interesting class of photothermal material, which when combined with other imageable nanoprobes could serve as a theranostic agent for imaging-guided photothermal therapy of cancer.

  14. Nanoparticle-enabled, image-guided treatment planning of target specific RNAi therapeutics in an orthotopic prostate cancer model.

    PubMed

    Lin, Qiaoya; Jin, Cheng S; Huang, Huang; Ding, Lili; Zhang, Zhihong; Chen, Juan; Zheng, Gang

    2014-08-13

    The abilities to deliver siRNA to its intended action site and assess the delivery efficiency are challenges for current RNAi therapy, where effective siRNA delivery will join force with patient genetic profiling to achieve optimal treatment outcome. Imaging could become a critical enabler to maximize RNAi efficacy in the context of tracking siRNA delivery, rational dosimetry and treatment planning. Several imaging modalities have been used to visualize nanoparticle-based siRNA delivery but rarely did they guide treatment planning. We report a multimodal theranostic lipid-nanoparticle, HPPS(NIR)-chol-siRNA, which has a near-infrared (NIR) fluorescent core, enveloped by phospholipid monolayer, intercalated with siRNA payloads, and constrained by apoA-I mimetic peptides to give ultra-small particle size (<30 nm). Using fluorescence imaging, we demonstrated its cytosolic delivery capability for both NIR-core and dye-labeled siRNAs and its structural integrity in mice through intravenous administration, validating the usefulness of NIR-core as imaging surrogate for non-labeled therapeutic siRNAs. Next, we validated the targeting specificity of HPPS(NIR)-chol-siRNA to orthotopic tumor using sequential four-steps (in vivo, in situ, ex vivo and frozen-tissue) fluorescence imaging. The image co-registration of computed tomography and fluorescence molecular tomography enabled non-invasive assessment and treatment planning of siRNA delivery into the orthotopic tumor, achieving efficacious RNAi therapy.

  15. In situ assembly of well-dispersed Ni nanoparticles on silica nanotubes and excellent catalytic activity in 4-nitrophenol reduction.

    PubMed

    Zhang, Shenghuan; Gai, Shili; He, Fei; Ding, Shujiang; Li, Lei; Yang, Piaoping

    2014-10-01

    The easy aggregation nature of ferromagnetic nanoparticles (NPs) prepared by conventional routes usually leads to a large particle size and low loading, which greatly limits their applications to the reduction of 4-nitrophenol (4-NP). Herein, we developed a novel in situ thermal decomposition and reduction strategy to prepare Ni nanoparticles/silica nanotubes (Ni/SNTs), which can markedly prevent the aggregation and growth of Ni NPs, resulting in an ultra-small particle size (about 6 nm), good dispersion and especially high loading of Ni NPs. It was found that Ni/SNTs, which have a high specific surface area (416 m(2) g(-1)), exhibit ultra-high catalytic activity in the 4-NP reduction (complete reduction of 4-NP within only 60 s at room temperature), which is superior to most noble metal (Au, Pt, and Pd) supported catalysts. Ni/SNTs still showed high activity even after re-use for several cycles, suggesting good stability. In particular, the magnetic property of Ni/SNTs makes it easy to recycle for reuse.

  16. De-alloyed platinum nanoparticles

    DOEpatents

    Strasser, Peter; Koh, Shirlaine; Mani, Prasanna; Ratndeep, Srivastava

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  17. Nanoparticles for Biomedical Imaging

    SciTech Connect

    Nune, Satish K.; Gunda, Padmaja; Thallapally, Praveen K.; Lin, Ying-Ying; Forrest, Laird M.; Berkland, Cory J.

    2009-11-01

    Background: Synthetic nanoparticles are emerging as versatile tools in biomedical applications, particularly in the area of biomedical imaging. Nanoparticles 1 to 100 nm in diameter possess dimensions comparable to biological functional units. Diverse surface chemistries, unique magnetic properties, tunable absorption and emission properties, and recent advances in the synthesis and engineering of various nanoparticles suggest their potential as probes for early detection of diseases such as cancer. Surface functionalization has further expanded the potential of nanoparticles as probes for molecular imaging. Objective: To summarize emerging research of nanoparticles for biomedical imaging with increased selectivity and reduced non-specific uptake with increased spatial resolution containing stabilizers conjugated with targeting ligands. Methods: This review summarizes recent technological advances in the synthesis of various nanoparticle probes, and surveys methods to improve the targeting of nanoparticles for their applications in biomedical imaging. Conclusion: Structural design of nanomaterials for biomedical imaging continues to expand and diversify. Synthetic methods have aimed to control the size and surface characteristics of nanoparticles to control distribution, half-life and elimination. Although molecular imaging applications using nanoparticles are advancing into clinical applications, challenges such as storage stability and long-term toxicology should continue to be addressed. Keywords: nanoparticle synthesis, surface modification, targeting, molecular imaging, and biomedical imaging.

  18. A nanoparticle in plasma

    SciTech Connect

    Martynenko, Yu. V.; Nagel', M. Yu.; Orlov, M. A.

    2009-06-15

    Charge and energy fluxes onto a nanoparticle under conditions typical of laboratory plasmas are investigated theoretically. Here, by a nanoparticle is meant a grain the size of which is much smaller than both the electron Larmor radius and Debye length and the thermionic emission from which is not limited by the space charge. Under conditions at which thermionic emission plays an important role, the electric potential and temperature T{sub p} of a nanoparticle are determined by solving a self-consistent set of equations describing the balance of energy and charge fluxes onto the nanoparticle. It is shown that, when the degree of plasma ionization exceeds a critical level, the potential of the nanoparticle and the energy flux onto it increase with increasing nanoparticle temperature, so that, starting from a certain temperature, the nanoparticle potential becomes positive. The critical degree of ionization starting from which the potential of a nanoparticle is always positive is determined as a function of the plasma density and electron temperature. The nanoparticle temperature T{sub p} corresponding to the equilibrium state of a positively charged nanoparticle is found as a function of the electron density for different electron temperatures.

  19. Enhancing photothermal cancer therapy by clustering gold nanoparticles into spherical polymeric nanoconstructs

    NASA Astrophysics Data System (ADS)

    Iodice, Carmen; Cervadoro, Antonio; Palange, AnnaLisa; Key, Jaehong; Aryal, Santosh; Ramirez, Maricela R.; Mattu, Clara; Ciardelli, Gianluca; O'Neill, Brian E.; Decuzzi, Paolo

    2016-01-01

    Gold nanoparticles (AuNPs) have been proposed as agents for enhancing photothermal therapy in cancer and cardiovascular diseases. Different geometrical configurations have been used, ranging from spheres to rods and more complex star shapes, to modulate optical and ablating properties. In this work, multiple, ultra-small 6 nm AuNPs are encapsulated into larger spherical polymeric nanoconstructs (SPNs), made out of a poly(lactic acid-co-glycol acid) (PLGA) core stabilized by a superficial lipid-PEG monolayer. The optical and photothermal properties of the resulting nanoconstructs (Au-SPNs) are modulated by varying the initial loading input of AuNPs, ranging between 25 and 150 μgAu. Au-SPNs exhibit a hydrodynamic diameter varying from ~100 to 180 nm, growing with the gold content, and manifest up to 2-fold increase in thermal energy production per unit mass of gold for an initial input of 100 μgAu. Au-SPNs are stable under physiological conditions up to 7 days and have direct cytotoxic effect on tumor cells. The superior photothermal performance of Au-SPNs is assessed in vitro on monolayers of breast cancer cells (SUM-159) and tumor spheroids of glioblastoma multiforme cells (U87-MG). The encapsulation of small AuNPs into larger spherical nanoconstructs enhances photothermal ablation and could favor tumor accumulation.

  20. Transferring biomarker into molecular probe: melanin nanoparticle as a naturally active platform for multimodality imaging.

    PubMed

    Fan, Quli; Cheng, Kai; Hu, Xiang; Ma, Xiaowei; Zhang, Ruiping; Yang, Min; Lu, Xiaomei; Xing, Lei; Huang, Wei; Gambhir, Sanjiv Sam; Cheng, Zhen

    2014-10-29

    Developing multifunctional and easily prepared nanoplatforms with integrated different modalities is highly challenging for molecular imaging. Here, we report the successful transfer of an important molecular target, melanin, into a novel multimodality imaging nanoplatform. Melanin is abundantly expressed in melanotic melanomas and thus has been actively studied as a target for melanoma imaging. In our work, the multifunctional biopolymer nanoplatform based on ultrasmall (<10 nm) water-soluble melanin nanoparticle (MNP) was developed and showed unique photoacoustic property and natural binding ability with metal ions (for example, (64)Cu(2+), Fe(3+)). Therefore, MNP can serve not only as a photoacoustic contrast agent, but also as a nanoplatform for positron emission tomography (PET) and magnetic resonance imaging (MRI). Traditional passive nanoplatforms require complicated and time-consuming processes for prebuilding reporting moieties or chemical modifications using active groups to integrate different contrast properties into one entity. In comparison, utilizing functional biomarker melanin can greatly simplify the building process. We further conjugated αvβ3 integrins, cyclic c(RGDfC) peptide, to MNPs to allow for U87MG tumor accumulation due to its targeting property combined with the enhanced permeability and retention (EPR) effect. The multimodal properties of MNPs demonstrate the high potential of endogenous materials with multifunctions as nanoplatforms for molecular theranostics and clinical translation.