31 results on '"Jun Hua Wu"'
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2. Synthesis and Characterization of Magnetic–Luminescent Fe3O4–CdSe Core–Shell Nanocrystals
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Ji Hyun Min, Jun Hua Wu, HongLing Liu, Young Keun Kim, and Ju Hun Lee
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Materials science ,Nanostructure ,Magnetism ,Band gap ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Characterization (materials science) ,chemistry.chemical_compound ,chemistry ,Nanocrystal ,0210 nano-technology ,Luminescence ,Bifunctional ,Superparamagnetism - Abstract
Nanostructures organized in unordinary spatial arrangements with multiple components such as core–shell configurations endow structures, material properties and functions that differ from the individual bulk components. In this study, we report the synthesis and characterization of bifunctional magnetic–luminescent Fe3O4–CdSe core–shell nanocrystals with core diameter and shell thickness of 10 and 2 nm, respectively, by controlled sequential reactions. The nanocrystals exhibit well-defined superparamagnetic behavior with high susceptibility at RT. Moreover, the fluorescent measurements demonstrate two major kinds of emission peaks, one at 572 nm originating from the bandgap excitons and the other at 680 nm being surface-associated. These core–shell nanocrystals, coupling the optical sensing element with the magnetic actuator in a peculiar nanostructure are thereby prospected for fundamental study and various applications where multifunctionality is required.
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- 2018
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3. Facile synthesis of multifunctional La1−xSrxMnO3@Au core–shell nanoparticles for biomedical applications
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Jun Hua Wu, Ning Fang, HongLing Liu, Xiao Liu, Mei-Xia Zhao, Wei-Hua Guo, and Xue-Mei Li
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Materials science ,General Chemical Engineering ,Nanoparticle ,Nanotechnology ,General Chemistry ,chemistry.chemical_compound ,chemistry ,Ferromagnetism ,Transmission electron microscopy ,Absorption band ,Curie temperature ,Surface plasmon resonance ,Ethylene glycol ,Superparamagnetism - Abstract
Multifunctional high-performance La1−xSrxMnO3@Au core–shell nanoparticles were successfully synthesized by a modified nanoemulsion method with the assistance of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO). X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses confirm the structure and morphology of the nanoparticles. The measurements obtained using ultraviolet-visible light absorbance spectrometry (UV-vis), vibrating sample magnetometry (VSM), and a physical property measurement system (PPMS) demonstrate that the nanoparticles exhibit a surface plasmon resonance (SPR) absorption band around 561 nm from nanostructured Au and a unique magnetic nature at room temperature. Particularly, a sharp, tight phase transition from ferromagnetic to superparamagnetic states is observed in a free-standing La1−xSrxMnO3 nanoparticle system for the first time with a Curie temperature around room temperature. The cytotoxicity of the nanoparticles was studied for safe biomedical applications using an MTT assay. The results show that the La1−xSrxMnO3@Au core–shell nanoparticles with lower cytotoxicity, well-defined magnetic and optical properties are promising for optical, magnetic, and biomedical application.
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- 2015
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4. Synthesis and Characterization of Polymer-Laced Cu-ZnO Nanoparticles
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Xue-Mei Li, Xian-Hong Wang, Jun Hua Wu, Hong Ling Liu, Xiao Liu, Wen Zheng Chen, and Zheng Guan
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chemistry.chemical_classification ,Photoluminescence ,Materials science ,Absorption spectroscopy ,Reducing agent ,General Engineering ,Nanoparticle ,Polymer ,Catalysis ,Solvent ,chemistry ,Transmission electron microscopy ,Organic chemistry ,Nuclear chemistry - Abstract
The polymer-laced Cu-ZnO nanoparticles were successfully synthesized by one-pot non-aqueous nanoemulsion method with the use of PEO-PPO-PEO as the surfactant, C14H29CH(OH)CH2OH as the reducing agent, octyl ether as the solvent, Zn (acac)2 and Cu (acac)2 as precursors. The Morphology and structure of nanoparticles were analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). UV-visible absorption spectroscopy (UV-vis) and photoluminescence spectrometry (PL) were employed to valuate the optical properties of the nanoparticles. The Cu-ZnO nanoparticles with well defined optical properties are promising for optical, catalytic and biomedical applications.
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- 2014
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5. Synthesis of Fluorescent Magnetic and Plasmonic-Hybrid Multifunctional Nanopaticles
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Xiao Liu, Hong Ling Liu, Zheng Guan, Wen Zheng Chen, Jun Hua Wu, Xian-Hong Wang, and Xue-Mei Li
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Materials science ,Absorption spectroscopy ,General Engineering ,Nanoparticle ,Nanotechnology ,Polyvinyl alcohol ,Solvent ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Chemical engineering ,Transmission electron microscopy ,Ethylene glycol ,Powder diffraction - Abstract
FeAu/ZnO nanoparticles were successfully synthesized by nanoemulsion process with the use of poly (ethylene glycol)-block-poly (propylene glycol)-block-poly (ethylene glycol) as the surfactant. The characterization of the FeAu/ZnO nanoparticles was performed using X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and UV-visible absorption spectroscopy, showing that the polymer-laced nanoparticles reveal high crystallinity, excellent dispersibility and well defined optical performance. The process of solvent dispersion-collection of FeAu/ZnO nanoparticles indicates that the nanoparticles possess good magnetic property for applications.
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- 2014
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6. Synthesis and characterization of polymer-coated AgZnO nanoparticles with enhanced photocatalytic activity
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Xian-Hong Wang, Hongling Liu, Cheng Wenzheng, Jun-Hua Wu, Wen Xing Zhang, Xiao Liu, and Xue-Mei Li
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Materials science ,General Chemical Engineering ,Analytical chemistry ,Nanoparticle ,General Chemistry ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Chemical engineering ,X-ray photoelectron spectroscopy ,Rhodamine B ,Photocatalysis ,Fourier transform infrared spectroscopy ,High-resolution transmission electron microscopy ,Ethylene glycol - Abstract
The polymer-coated AgZnO nanoparticles were synthesized via a one-pot process with the assistance of the triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO). The nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) including the mode of high resolution (HRTEM) and by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible light absorbance spectrometry (UV-vis) and photoluminescence spectrophotometry (PL). It is found that the nanoparticles reveal high crystallinity, good dispersibility, and excellent optical performance both in organic and aqueous solvents. The photocatalytic behavior of the AgZnO nanoparticles was scrutinized using rhodamine B (RhB) as probe molecule. The results show that the degradation efficiency of the AgZnO nanoparticles is higher than that of the ZnO nanoparticles under both UV and sunlight irradiation, 89.5% and 66.9% for the former and 52.7% and 37.5% for the latter after 90 minute exposure, respectively. Moreover, the AgZnO nanoparticles were found to have the photocatalytic efficiency unaltered after 5 cycles of use as tested. Our results demonstrate that the nanostructured AgZnO nanoparticles exhibit enhanced photocatalytic performance and high stability. Consequently, the AgZnO nanoparticles are favorable candidates for potential application as a promising photocatalyst.
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- 2014
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7. 17β Estradiol regulation of connexin 43-based gap junction and mechanosensitivity through classical estrogen receptor pathway in osteocyte-like MLO-Y4 cells
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Xuhui Wang, Guang-Chao Wang, Jun-Hua Wu, and Jian Ren
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MAPK/ERK pathway ,medicine.medical_specialty ,Histology ,Physiology ,medicine.drug_class ,Endocrinology, Diabetes and Metabolism ,Estrogen receptor ,Connexin ,Osteocytes ,Cell Line ,Internal medicine ,medicine ,Humans ,Mechanotransduction ,Estradiol ,Fulvestrant ,Chemistry ,Gap junction ,Gap Junctions ,Cell biology ,medicine.anatomical_structure ,Endocrinology ,Microscopy, Fluorescence ,Estrogen ,Connexin 43 ,Osteocyte ,cardiovascular system ,sense organs ,biological phenomena, cell phenomena, and immunity ,Fluorescence Recovery After Photobleaching ,medicine.drug - Abstract
Connexin 43 (Cx43) plays an essential role in osteocyte mechanotransduction. Although estrogen involves in the adaptive responses of bone cells to mechanical loadings, its effects on osteocytic Cx43-based gap junction intercellular communication (GJIC) remain obscure. We found that 17β estradiol (E2) up-regulated Cx43, and enhanced GJIC in osteocyte-like MLO-Y4 cells in fluorescence recovery after photobleaching (FRAP) assay. Combination of E2 pre-treatment and oscillating fluid flow (OFF) further enhanced Cx43 expression and mitogen-activated protein kinase (MAPK) phosphorylation, comparing to E2 or OFF treatment alone. Both blocking of classical estrogen receptors (ERα/β) by fulvestrant and ERα knockdown by small interfering RNA inhibited E2-mediated Cx43 increase, while a GPR30-specific agonist G-1 failed to promote Cx43 expression. Our results suggest that the presence of E2 enhanced Cx43-based GJIC mainly via ERα/β pathway, and sensitized osteocytes to mechanical loading.
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- 2013
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8. Tunable synthesis and multifunctionalities of Fe3O4–ZnO hybrid core-shell nanocrystals
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HongLing Liu, Jun Hua Wu, Ji Hyun Min, Young Keun Kim, and XiaoYan Zhang
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chemistry.chemical_classification ,Photoluminescence ,Nanostructure ,Materials science ,Band gap ,Mechanical Engineering ,Nanotechnology ,Polymer ,Condensed Matter Physics ,Nanoshell ,Magnetization ,chemistry ,Nanocrystal ,Mechanics of Materials ,General Materials Science ,Superparamagnetism - Abstract
We report the tunable synthesis and multifunctionalities of Fe 3 O 4 –ZnO hybrid core-shell nanocrystals as prepared through controlled sequential nanoemulsion processes. The characterization shows the orderly variations of the structural, magnetic, photoluminescent and absorption properties of the nanocrystals versus the nanoshell thickness. The nanocrystals reveal structural features unique to the core-shell design and exhibit well-defined superparamagnetic behavior at room temperature. In opposite to the decreasing magnetization, both bandgap and induced surface emissions depend strongly on the increasing nanoshell thickness. Moreover, the FTIR analysis provides the fingerprints of the polymer surfactant, ZnO and Fe 3 O 4 in the same nano-entity and the core-shell nanocrystals could be directly dispersed in both aqueous and organic media for application readiness. Aptly tunable in nanostructures and thus optimized properties, this kind of monosized, high quality, and multifunctional core-shell nanocrystals could be of interest for fundamental studies and potential applications.
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- 2013
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9. Research on the Corn Stalk Composite Solvent Liquefaction
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Chu Nan Ma, Jun You Shi, Jun Hua Wu, Jiu Yin Pang, Xiangyu Li, and Yi Gang Zou
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Solvent ,chemistry.chemical_compound ,Petrochemical ,chemistry ,Chemical engineering ,Waste management ,Liquefaction ,Biomass ,General Medicine ,Straw ,Raw material ,Ethylene glycol ,Catalysis - Abstract
The northeast of China with rich sources of corn straw resources as raw materials, we take use of multi-component solvent as the liquefaction. Ethylene glycol, polyethylene glycol (200) and glycerol,the three kinds of solvent mixing for liquefacient. We got the optimum process conditions, which is reaction temperature is 160 °C, reaction time is 60 minutes, catalyst amount to total liquefied agent is 3%. On the product analysis shows that the solvent liquefied corn straw can be effectively degradation. The results indicated that the liquefaction products contains phenols, aldehydes, et al, such as carboxylic acid group material, which can be converted into the corresponding ether, ester etc polymer compound that can be used in plastic, building heat preservation etc partly replace at present, these resources products from petrochemical. Straw liquefaction can reduce dependence on fossil energy, and make up for a single energy products of the shortcomings of the economy, which have great significant strategic.
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- 2012
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10. One-pot synthesis and characterization of bifunctional Au–Fe3O4 hybrid core–shell nanoparticles
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Ji Hyun Min, HongLing Liu, Jun Hua Wu, and Young Keun Kim
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Materials science ,Nanostructure ,Mechanical Engineering ,One-pot synthesis ,Metals and Alloys ,Nanoparticle ,Nanotechnology ,Chemical synthesis ,Characterization (materials science) ,Magnetization ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Materials Chemistry ,Bifunctional ,Superparamagnetism - Abstract
We report the one-pot synthesis of bifunctional Au–Fe3O4 hybrid core–shell nanoparticles by controlled sequential reactions. The core–shell nanostructure of the resultant nanoparticles is identified by XRD and TEM, which is further substantiated by the changes in the corresponding physical and chemical properties. The nanoparticles exhibit a well-shaped absorption band in the visible region with a remarkable red-shifting to ∼592 nm and show clear superparamagnetic behavior at room temperature along with enhanced susceptibility, demonstrating the integration of the optical and magnetic functions of the respective components in one entity. This kind of bifunctional optical-magnetic core–shell nanoparticles could be of interest in interfacial proximity effects due to the unique spatial nanostructure configuration and have potential applications in various areas.
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- 2012
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11. Direct synthesis of water-dispersible 2 nm FePt nanocrystals without ligand exchange
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Peng Hou, HongLing Liu, XiaoYan Zhang, and Jun Hua Wu
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chemistry.chemical_classification ,Aqueous solution ,Materials science ,Nanotechnology ,Polymer ,Condensed Matter Physics ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Nanocrystal ,Chemical engineering ,Phase (matter) ,Copolymer ,General Materials Science ,Fourier transform infrared spectroscopy ,Ethylene glycol - Abstract
Water-dispersible 2 nm FePt ultrasmall nanocrystals coated by a biocompatible triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) were directly synthesized in a single-step nanoemulsion process. The FTIR investigation proves the PEO-PPO-PEO molecules on the surface of the resulting nanocrystals, which render the nanocrystals hydrophilic for aqueous dispersion without using conventional ligand exchange and offer proper protection of the nanocrystals from oxidation. The structural and morphological analysis reveals both single-crystallinity and high crystallinity of the nanocrystals in the face-centered cubic phase, with an excellent monosize distribution of 1.95 ± 0.18 nm in diameter. Moreover, the polymer-capped nanocrystals possess well-defined magnetic behavior and the aqueous dispersion–collection process of the nanocrystals was demonstrated for application readiness of such ultrasmall nanocrystals in aqueous media.
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- 2012
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12. A study on surfactant-free growth of silver-carbon nanocables by H2SO4-mediated hydrothermal process
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Jun Hua Wu, Shengyi Zhang, Helin Niu, XuHu Wu, Yuanhao Gao, Min Qiu, HongLing Liu, Chang-Jie Mao, and Jiming Song
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Nanostructure ,Materials science ,Reducing agent ,Mechanical Engineering ,Nanowire ,chemistry.chemical_element ,Condensed Matter Physics ,Hydrothermal circulation ,Pulmonary surfactant ,chemistry ,Ferromagnetism ,Chemical engineering ,Mechanics of Materials ,General Materials Science ,Carbon ,Deposition (law) - Abstract
We study the one-pot facile hydrothermal growth of ultralong silver-carbon (Ag-C) nanocables with Ag nanowires as the cores and carbon as the sheaths through the mediation of H2SO4 and without using an organic surfactant. In the investigation, Ag-C nanostructures were systematically and extensively examined as a function of both temperature and H2SO4 concentration to locate the optimal conditions for preparing ultralong, robust, and uniform Ag-C coaxial nanocables at T = 180 °C and 0.5 M H2SO4. The characterization clearly demonstrated a simple, efficient, and surfactant-free synthesis of Ag-C nanocables. In the hydrothermal process, glycerol acts as both reducing agent and carbon source, while H2SO4 mediates the directional growth of the silver nanowire core and assists the deposition of carbon. Moreover, the nanocables manifest unusual ferromagnetism at room temperature and a plausible mechanism of forming Ag-C nanocables was proposed as a result of the chain-like hydrogen sulfate compounds owing to the H2SO4 mediation.
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- 2011
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13. Facile growth of monocrystalline gold–iron nanocrystals by polymer nanoemulsion
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Jun Hua Wu, Peng Hou, WengXing Zhang, and HongLing Liu
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chemistry.chemical_classification ,Materials science ,Dispersity ,Nanotechnology ,Polymer ,Inorganic Chemistry ,Monocrystalline silicon ,Ferromagnetism ,Nanocrystal ,chemistry ,Electron diffraction ,Transmission electron microscopy ,General Materials Science ,Surface plasmon resonance - Abstract
Monodisperse, monocrystalline AuFe optical–magnetic multifunctional nanocrystals were prepared by the nanoemulsion method using a copolymer surfactant. The structure and properties of the monocrystalline nanocrystals were analyzed by X-ray diffraction, transmission electron microscopy (TEM, including high-resolution TEM), selected-area electron diffraction, UV-vis spectroscopy, and vibration sampling magnetometry. The characterization shows the outstanding monodispersity and high monocrystallinity of the nanocrystals, which possess both well-defined optical and magnetic properties revealing broadband absorption with the surface plasmon resonance, peaking at ~600 nm, and clear soft ferromagnetic behavior at room temperature. Such long-term stable, monocrystalline AuFe nanocrystals have novel optical and magnetic properties, which may offer exciting opportunities in fundamental studies and tremendous applications.
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- 2011
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14. Synthesis of monosized core–shell Fe3O4/Au multifunctional nanoparticles by PVP-assisted nanoemulsion process
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HongLing Liu, Peng Hou, WengXing Zhang, and Jun Hua Wu
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Nanostructure ,Materials science ,Infrared spectroscopy ,Binary compound ,Nanoparticle ,Nanotechnology ,engineering.material ,Crystallinity ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Pulmonary surfactant ,Coating ,chemistry ,engineering ,Fourier transform infrared spectroscopy - Abstract
Monosized core–shell Fe3O4/Au magnetic–optic multifunctional nanoparticles were synthesized by a modified nanoemulsion process. The formation of the core–shell nanostructure was accomplished in the presence of poly(vinylpyrrolidone) (PVP) as the surfactant in two consecutive steps. The comparison FTIR study proves the PVP coating on the surface of the resultant nanoparticles, whereas the morphological analysis illustrates the nanoparticle shape, nanostructuring, size and size distribution and shows the excellent monodispersity
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- 2010
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15. Synthesis and Characterization of ${\rm Fe-FeO}_{\rm x}$ Core-Shell Nanowires
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Hae Ryong Kim, Jun Hua Wu, Ki Seok Jeon, Young Keun Kim, Ju Hun Lee, Yung Doug Suh, Jong Heun Lee, and Ji Sung Lee
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Materials science ,Nanostructure ,Anodizing ,Oxide ,Iron oxide ,Nanowire ,Nanotechnology ,Electronic, Optical and Magnetic Materials ,Magnetization ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Transmission electron microscopy ,Electrical and Electronic Engineering ,Magnetite - Abstract
We report the synthesis and characterization of Fe-FeOx core-shell nanowires by thermal conversion of the Fe nanowires from pulse electrodeposition in anodized aluminum oxide (AAO) nanotemplates under various conditions. Well-defined core-shell nanostructure of the Fe-FeOx nanowires was confirmed by TEM and corresponding elemental line scanning and point scanning. The type of the iron oxide in the shell was identified using nano-Raman spectroscopy, which exposes magnetite to be the major constituent. The magnetic measurements demonstrate that the nanowires are robustly soft magnetic, with the magnetization tunable by heat treatment parameters and a weak magnetic easy direction parallel to the nanowire axis.
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- 2008
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16. Sub 5 nm Fe3O4 nanocrystals via coprecipitation method
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Hong Ling Liu, Seung Pil Ko, Myung-Hwa Jung, Jun Hua Wu, Jae Seon Ju, Young Keun Kim, and Ju Hun Lee
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Materials science ,Coprecipitation ,Annealing (metallurgy) ,Nanotechnology ,chemistry.chemical_compound ,Crystallinity ,Colloid and Surface Chemistry ,Nanocrystal ,Chemical engineering ,chemistry ,Particle size ,High-resolution transmission electron microscopy ,Superparamagnetism ,Magnetite - Abstract
Magnetite nanocrystals of 2–4 nm were synthesized by a chemical coprecipitation method, by which the particle size was controlled by the reaction temperature. The nanocrystals were investigated by XRD, TEM/HRTEM, VSM and SQUID. It is found that the nanocrystals reveal well-defined superparamagnetic behavior before and after annealing, while the observation of the distinct lattices manifest the high crystallinity of the ultrasmall particles.
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- 2008
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17. Sub 5 nm magnetite nanoparticles: Synthesis, microstructure, and magnetic properties
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Young Keun Kim, Jae Seon Ju, Sangsig Kim, Seung Pil Ko, Jun Hua Wu, and Hong Ling Liu
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Materials science ,Coprecipitation ,Magnetism ,Mechanical Engineering ,Analytical chemistry ,Nanoparticle ,Condensed Matter Physics ,Microstructure ,law.invention ,SQUID ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,law ,Condensed Matter::Superconductivity ,General Materials Science ,High-resolution transmission electron microscopy ,Superparamagnetism ,Magnetite - Abstract
Magnetite particles of 2–4 nm were synthesized by an economic, biocompatible chemical coprecipitation route, with their size tuned by the reaction temperature. The microstructure and morphology of the nanoparticles were characterized by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM), whereas the magnetic properties were investigated by vibrating sample magnetometry (VSM) and superconducting quantum interference device (SQUID). It is found that the nanoparticles demonstrate well-defined superparamagnetic behavior as prepared and after annealing. Distinct lattices were observed which manifest the high crystallinity of such ultrasmall particles and the finite-size effect was revealed by analyzing the corresponding microstructure and magnetism.
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- 2007
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18. Synthesis of bi-phase dispersible core-shell FeAu@ZnO magneto-opto-fluorescent nanoparticles
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Jun-Hua Wu, Ning Fang, Xian-Hong Wang, Xiao Liu, Xue-Mei Li, and HongLing Liu
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Multidisciplinary ,Materials science ,Nanostructure ,technology, industry, and agriculture ,Nanoparticle ,macromolecular substances ,Coercivity ,Article ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Phase (matter) ,Surface plasmon resonance ,High-resolution transmission electron microscopy ,Ethylene glycol ,Superparamagnetism - Abstract
Bi-phase dispersible core-shell FeAu@ZnO magneto-opto-fluorescent nanoparticles were synthesized by a modified nanoemulsion process using poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) as the surfactant. The morphology and crystal structure of the nanoparticles were studied by TEM/HRTEM and XRD. The nanoparticles manifest soft ferromagnetic and/or near superparamagnetic behavior with a small coercivity of ~19 Oe at room temperature. The corresponding magnetic hysteresis curves were elucidated by the modified Langevin equation. The FTIR study confirms the PEO-PPO-PEO molecules on the surface of the nanoparticles. The UV-vis and PL results reveal the well-behaved absorption bands including surface plasmon resonance and multiple visible fingerprint photoluminescent emissions of the nanoparticles dispersed in both hydrophilic and hydrophobic solvents. Moreover, the processes of solvent dispersion-collection of the nanoparticles were demonstrated for application readiness of such core-shell nanostructures.
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- 2015
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19. Control of magnetic anisotropy of Co nanowires
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Qun Xian Liu, Young Keun Kim, Jun Hua Wu, Seung Pil Ko, Jiung Cho, Ji Hyun Min, and Joon Young Soh
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Materials science ,business.industry ,Annealing (metallurgy) ,Nanowire ,Nanotechnology ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Magnetic field ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,Magnetic anisotropy ,Crystallinity ,chemistry ,Aluminium oxide ,Optoelectronics ,Thermal stability ,business ,Current density - Abstract
Cobalt nanowires were fabricated by DC electrodeposition onto anodic aluminium oxide (AAO) templates. The effects of AAO pore diameter, current density, pH, annealing and deposition under external magnetic fields on the structure and magnetic properties of the nanowire arrays were studied. It is found that the smaller pore size produces high crystallinity, resulting in improved magnetic performance at low current density. The pH can transform fcc-Co phase to hcp-Co phase, with the easy axis along the nanowire axis switched over to the perpendicular direction. Annealing demonstrates excellent thermal stability of the magnetic nanowire arrays at high temperature. The application of external magnetic field during deposition influences the growth habit of the nanowires, leading to the change in the magnetic properties.
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- 2006
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20. Facile synthesis and photocatalytic activity of bi-phase dispersible Cu-ZnO hybrid nanoparticles
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Xiao Liu, Xue-Mei Li, Jun Hua Wu, Ning Fang, Wen Xing Zhang, Xian-Hong Wang, and Hong Ling Liu
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Bi-phase dispersible ,Aqueous solution ,Materials science ,medicine.diagnostic_test ,Nano Express ,technology, industry, and agriculture ,Nanochemistry ,Nanoparticle ,Nanotechnology ,Condensed Matter Physics ,Crystallinity ,chemistry.chemical_compound ,Materials Science(all) ,chemistry ,X-ray photoelectron spectroscopy ,Nanoemulsion ,Spectrophotometry ,medicine ,Photocatalysis ,Photocatalytic performance ,General Materials Science ,Cu-ZnO nanoparticles ,Ethylene glycol ,Nuclear chemistry - Abstract
Bi-phase dispersible Cu-ZnO hybrid nanoparticles were synthesized by one-pot non-aqueous nanoemulsion with the use of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) as the surfactant. The transmission electron microscopy (TEM) and X-ray diffraction (XRD) show high crystallinity of the Cu-ZnO hybrid nanoparticles and an average particle size of ~19.4 nm. The ultraviolet-visible light absorbance spectrometry (UV-vis) and photoluminescence spectrophotometry (PL) demonstrate well dispersibility and excellent optical performance of Cu-ZnO hybrid nanoparticles both in organic and aqueous solvent. The X-ray photoelectron spectroscopy (XPS) confirms Cu(1+) and Cu(2+) in ZnO. The observation using Sudan red (III) as probe molecule reveals that the Cu-ZnO hybrid nanoparticles possess enhanced photocatalytic activity and stability which are promising for potential applications in photocatalysis.
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- 2014
21. Facile synthesis and optical properties of polymer-laced ZnO-Au hybrid nanoparticles
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Xiao Liu, Cheng Wenzheng, Hongqin Shao, Xian-Hong Wang, Jun Hua Wu, HongLing Liu, Xue-Mei Li, and XiaoYan Zhang
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36.20.-r ,chemistry.chemical_classification ,Materials science ,Nano Express ,Optical properties ,ZnO-Au nanoparticles ,Nanochemistry ,Nanoparticle ,Nanotechnology ,Polymer ,Condensed Matter Physics ,78.67.Bf ,68.05.Gh ,Crystallinity ,chemistry.chemical_compound ,Materials Science(all) ,Nanoemulsion ,Chemical engineering ,chemistry ,Photocatalysis ,General Materials Science ,Surface plasmon resonance ,Photodegradation ,Ethylene glycol - Abstract
Bi-phase dispersible ZnO-Au hybrid nanoparticles were synthesized via one-pot non-aqueous nanoemulsion using the triblock copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) as the surfactant. The characterization shows that the polymer-laced ZnO-Au nanoparticles are monosized and of high crystallinity and demonstrate excellent dispersibility and optical performance in both organic and aqueous medium, revealing the effects of quantum confinement and medium. The findings show two well-behaved absorption bands locating at approximately 360 nm from ZnO and between 520 and 550 nm from the surface plasmon resonance of the nanosized Au and multiple visible fingerprint photoluminescent emissions. Consequently, the wide optical absorbance and fluorescent activity in different solvents could be promising for biosensing, photocatalysis, photodegradation, and optoelectronic devices.
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- 2014
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22. Phase changeable silver selenide thin films fabricated by pulse electrodeposition
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Moon Kyu Cho, Boo Hyun An, Young Keun Kim, Heon Lee, Jun Hua Wu, Ki Yeon Yang, and Hye Min Ji
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Materials science ,Nanostructure ,business.industry ,Nanowire ,General Physics and Astronomy ,Nanotechnology ,chemistry.chemical_compound ,Carbon film ,chemistry ,Phase (matter) ,Selenide ,Optoelectronics ,General Materials Science ,Electrical measurements ,Orthorhombic crystal system ,Thin film ,business - Abstract
We have used a simple and direct method to successfully prepare Ag2Se thin films by pulse electrodeposition from a single aqueous solution of Ag and Se ions. The composition analysis confirms the stoichiometry and the morphological characterization shows that the thin films are dense and smooth. The films have the orthorhombic structure of regular Ag2Se materials at room temperature, while the electrical measurements reveal an interesting electrical behavior, similar to that of the Ag2Se nanowire arrays. The Ag2Se thin films were successfully deposited into polymer templates to form well-defined Ag2Se nanostructure, which provides a possibility to apply the method to high density, non-volatile memories based on phase change materials.
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- 2009
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23. One-pot polyol synthesis of monosize PVP-coated sub-5nm Fe3O4 nanoparticles for biomedical applications
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Seung Pil Ko, Ji Hyun Min, Young Keun Kim, Ju Hun Lee, Jun Hua Wu, Myung-Hwa Jung, Boo Hyun An, and Hong Ling Liu
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chemistry.chemical_classification ,Materials science ,Polyvinylpyrrolidone ,Nanoparticle ,Nanotechnology ,Condensed Matter Physics ,Microstructure ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Crystallinity ,Polyol ,chemistry ,Chemical engineering ,medicine ,High-resolution transmission electron microscopy ,Superparamagnetism ,Magnetite ,medicine.drug - Abstract
Polyvinylpyrrolidone (PVP)-coated sub-5 nm monosize Fe 3 O 4 nanoparticles were synthesized by reduction of Fe(III) acetylacetonate in the presence of PVP polymer as surfactant in one-pot polyol process. Their microstructure and magnetic properties were characterized by XRD, TEM/HRTEM and VSM. It is found that the nanoparticles have high crystallinity with distinct lattices and the magnetic measurements reveal their well-defined superparamagnetic behavior at room temperature. Such Fe 3 O 4 nanoparticles with tailorable size and tunable magnetic properties are promising for biomedical applications.
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- 2007
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24. Isolation of DNA using magnetic nanoparticles coated with dimercaptosuccinic acid
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Mi Kyung Woo, Chae Seung Lim, Ji Hyun Min, Jun Hua Wu, Jin Woo Jang, Young Keun Kim, and Ha Young Yoon
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Chromatography ,Surface Properties ,Biophysics ,Magnetic separation ,Cell Biology ,DNA ,Chemical Fractionation ,Biochemistry ,DNA extraction ,law.invention ,chemistry.chemical_compound ,genomic DNA ,chemistry ,law ,Magnets ,Surface modification ,Magnetic nanoparticles ,Humans ,Nanoparticles ,Succimer ,Molecular Biology ,Polymerase chain reaction ,Superparamagnetism - Abstract
Lately, the isolation of DNA using magnetic nanoparticles has received increased attention owing to their facile manipulation and low costs. Although methods involving their magnetic separation have been extensively studied, there is currently a need for an efficient technique to isolate DNA for highly sensitive diagnostic applications. We describe herein a method to isolate and purify DNA using biofunctionalized superparamagnetic nanoparticles synthesized by a modified polyol method to obtain the desired monodispersity, followed by surface modification with meso-2,3-dimercaptosuccinic acid (DMSA) containing carboxyl groups for DNA absorption. The DMSA-coated magnetic nanoparticles (DMSA-MNPs) were used for the isolation of DNA, with a maximum yield of 86.16%. In particular, we found that the isolation of DNA using small quantities of DMSA-MNPs was much more efficient than that using commercial microbeads (NucliSENS-easyMAG, BioMerieux). Moreover, the DMSA-MNPs were successfully employed in the isolation of genomic DNA from human blood. In addition, the resulting DNA–nanoparticle complex was directly subjected to PCR amplification without prior elution, which could eventually lead to simple, rapid, sensitive and integrated diagnostic systems.
- Published
- 2013
25. 17β-estradiol rapidly activates calcium release from intracellular stores via the GPR30 pathway and MAPK phosphorylation in osteocyte-like MLO-Y4 cells
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Jun Hua Wu and Jian Ren
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MAPK/ERK pathway ,medicine.medical_specialty ,Endocrinology, Diabetes and Metabolism ,chemistry.chemical_element ,Estrogen receptor ,Calcium ,Biology ,Osteocytes ,Receptors, G-Protein-Coupled ,Mice ,Endocrinology ,Internal medicine ,medicine ,Animals ,Orthopedics and Sports Medicine ,Phosphorylation ,Receptor ,Cells, Cultured ,Calcium metabolism ,Mitogen-Activated Protein Kinase Kinases ,Dose-Response Relationship, Drug ,Estradiol ,Estrogens ,chemistry ,Receptors, Estrogen ,Female ,Signal transduction ,GPER ,Signal Transduction - Abstract
Estrogen regulates critical cellular functions, and its deficiency initiates bone turnover and the development of bone mass loss in menopausal females. Recent studies have demonstrated that 17β-estradiol (E(2)) induces rapid non-genomic responses that activate downstream signaling molecules, thus providing a new perspective to understand the relationship between estrogen and bone metabolism. In this study, we investigated rapid estrogen responses, including calcium release and MAPK phosphorylation, in osteocyte-like MLO-Y4 cells. E(2) elevated [Ca(2+)]( i ) and increased Ca(2+) oscillation frequency in a dose-dependent manner. Immunolabeling confirmed the expression of three estrogen receptors (ERα, ERβ, and G protein-coupled receptor 30 [GPR30]) in MLO-Y4 cells and localized GPR30 predominantly to the plasma membrane. E(2) mobilized calcium from intracellular stores, and the use of selective agonist(s) for each ER showed that this was mediated mainly through the GPR30 pathway. MAPK phosphorylation increased in a biphasic manner, with peaks occurring after 7 and 60 min. GPR30 and classical ERs showed different temporal effects on MAPK phosphorylation and contributed to MAPK phosphorylation sequentially. ICI182,780 inhibited E(2) activation of MAPK at 7 min, while the GPR30 agonist G-1 and antagonist G-15 failed to affect MAPK phosphorylation levels. G-1-mediated MAPK phosphorylation at 60 min was prevented by prior depletion of calcium stores. Our data suggest that E(2) induces the non-genomic responses Ca(2+) release and MAPK phosphorylation to regulate osteocyte function and indicate that multiple receptors mediate rapid E(2) responses.
- Published
- 2011
26. A multifunctional core-shell nanoparticle for dendritic cell-based cancer immunotherapy
- Author
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Sang Jin Lee, Taek-Chin Cheong, Jun Hua Wu, Ji Hyun Min, Jae-Seong Yang, Nam Hyuk Cho, Young Keun Kim, Sanguk Kim, Seung Yong Seong, and Daehong Kim
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medicine.medical_treatment ,T-Lymphocytes ,Biomedical Engineering ,Iron oxide ,Nanoparticle ,Bioengineering ,Nanotechnology ,Immunotherapy, Adoptive ,chemistry.chemical_compound ,Mice ,Cancer immunotherapy ,Neoplasms ,medicine ,Animals ,Humans ,General Materials Science ,Electrical and Electronic Engineering ,Drug Carriers ,Immunity, Cellular ,Chemistry ,fungi ,food and beverages ,Dendritic cell ,Immunotherapy ,Dendritic Cells ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Imaging agent ,Carcinoembryonic Antigen ,Nanomedicine ,Nanoparticles ,Iron oxide nanoparticles - Abstract
Dendritic cell-based cancer immunotherapy requires tumour antigens to be delivered efficiently into dendritic cells and their migration to be monitored in vivo. Nanoparticles have been explored as carriers for antigen delivery, but applications have been limited by the toxicity of the solvents used to make nanoparticles, and by the need to use transfection agents to deliver nanoparticles into cells. Here we show that an iron oxide-zinc oxide core-shell nanoparticle can deliver carcinoembryonic antigen into dendritic cells while simultaneously acting as an imaging agent. The nanoparticle-antigen complex is efficiently taken up by dendritic cells within one hour and can be detected in vitro by confocal microscopy and in vivo by magnetic resonance imaging. Mice immunized with dendritic cells containing the nanoparticle-antigen complex showed enhanced tumour antigen specific T-cell responses, delayed tumour growth and better survival than controls.
- Published
- 2011
27. Synthesis of streptavidin-FITC-conjugated core-shell Fe3O4-Au nanocrystals and their application for the purification of CD4+ lymphocytes
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Jun Hua Wu, Kyung Mi Lee, Chung Hee Sonn, Young Keun Kim, and Hong Ling Liu
- Subjects
Streptavidin ,CD4-Positive T-Lymphocytes ,Materials science ,Biophysics ,Bioengineering ,Nanotechnology ,Cell Separation ,Conjugated system ,Immunomagnetic separation ,Biomaterials ,Core shell ,chemistry.chemical_compound ,Mice ,Materials Testing ,Splenocyte ,Animals ,Humans ,Magnetite ,Fluorescent Dyes ,Immunomagnetic Separation ,Flow Cytometry ,Ferrosoferric Oxide ,Mice, Inbred C57BL ,Carbodiimides ,chemistry ,Nanocrystal ,Mechanics of Materials ,Isothiocyanate ,Ceramics and Composites ,Nanoparticles ,Indicators and Reagents ,Gold ,Fluorescein-5-isothiocyanate ,Spleen ,Nuclear chemistry - Abstract
We explored the feasibility of magnetite (Fe(3)O(4))-gold (Au) core-shell nanocrystals as a useful vehicle for biomedical application such as cell separation. Streptavidin-fluorescein isothiocyanate (STA-FITC) was conjugated to the surface of the Fe(3)O(4)-Au core-shell nanocrystals using a carbodimide activation protocol. These nanocrystals were further tested for their ability to bind CD4+ T lymphocytes, bound to biotin-labeled anti-CD4 mAbs, isolated from the spleen of C57BL/6 mice. Our data show that the Fe(3)O(4)-Au nanocrystals successfully pulled down CD4+ T lymphocytes from the whole splenocytes with high specificity. Therefore, our nanocrystals provide an efficient tool for the cell separation process and further present the dramatic potential to be applied to other areas of biomedical application including diagnosis, monitoring, and treatment of human diseases.
- Published
- 2008
28. Finite-size effect and magnetic properties of ultra-small magnetite nanocrystals for biomedical applications
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Jun Hua Wu, Seung Pil Ko, Hong Ling Liu, and Y. S. Kim
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Materials science ,Coprecipitation ,Magnetometer ,Nanoparticle ,law.invention ,chemistry.chemical_compound ,Magnetization ,Nuclear magnetic resonance ,chemistry ,Chemical engineering ,law ,Transmission electron microscopy ,Magnetic nanoparticles ,High-resolution transmission electron microscopy ,Magnetite - Abstract
The authors synthesized ultra-small magnetite (Fe3O4) nanoparticles using aqueous coprecipitation. The crystal structure of the samples was analyzed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The magnetic properties of the magnetite nanocrystals were investigated using a SQUID magnetometer.
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- 2006
- Full Text
- View/download PDF
29. Labeling of macrophage cell using biocompatible magnetic nanoparticles
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Ji Sung Lee, Ji Hyun Min, Jun Hua Wu, Kyung Mi Lee, Jaeho Jeong, Ah-Young Song, Young Keun Kim, Sung Tae Kim, and Kwanghee Kim
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Pulmonary surfactant ,Chemistry ,Biophysics ,General Physics and Astronomy ,Nanomedicine ,Surface modification ,Nanoparticle ,Magnetic nanoparticles ,Nanotechnology ,Cell sorting ,Cytotoxicity ,Superparamagnetism - Abstract
This work investigates the intrinsic cell labeling efficiency of the Fe3O4 nanoparticles prepared by a modified thermal decomposition method using nontoxic precursors and a biocompatible polymer surfactant. This method eliminates the current need for additional step of surface modification. The structural analysis reveals the highly crystalline feature of the nanoparticles, while the magnetic measurement shows their superparamagnetic behavior at room temperature. Fe3O4 nanoparticles were efficiently incorporated into the murine macrophage cells (RAW264.7) without visible cytotoxicity. Cell labeling efficiency was found to be over 90% as measured by magnetically activated cell sorting and physical property measurement system. Therefore, such Fe3O4 nanoparticles could provide a useful magnetic cell labeling tool for macrophage cells using their phagocytic/endocytic activity and further apply to the other relevant biomedical applications.
- Published
- 2011
- Full Text
- View/download PDF
30. Non-aqueous synthesis of water-dispersible Fe3O4–Ca3(PO4)2core–shell nanoparticles
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Jun Hua Wu, Peng Hou, Ji Hyun Min, Ah-Young Song, Young Keun Kim, and Hong Ling Liu
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chemistry.chemical_classification ,Materials science ,Nanostructure ,Aqueous solution ,Mechanical Engineering ,Nanoparticle ,Bioengineering ,General Chemistry ,Polymer ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Phase (matter) ,Copolymer ,Organic chemistry ,General Materials Science ,Electrical and Electronic Engineering ,Fourier transform infrared spectroscopy ,Ethylene glycol ,Nuclear chemistry - Abstract
The Fe(3)O(4)-Ca(3)(PO(4))(2) core-shell nanoparticles were prepared by one-pot non-aqueous nanoemulsion with the assistance of a biocompatible triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO), integrating the magnetic properties of Fe(3)O(4) and the bioactive functions of Ca(3)(PO(4))(2) into single entities. The Fe(3)O(4) nanoparticles were pre-formed first by thermal reduction of Fe(acac)(3) and then the Ca(3)(PO(4))(2) layer was coated by simultaneous deposition of Ca(2+) and PO(4)(3-). The characterization shows that the combination of the two materials into a core-shell nanostructure retains the magnetic properties and the Ca(3)(PO(4))(2) shell forms an hcp phase (a = 7.490 Å, c = 9.534 Å) on the Fe(3)O(4) surface. The magnetic hysteresis curves of the nanoparticles were further elucidated by the Langevin equation, giving an estimation of the effective magnetic dimension of the nanoparticles and reflecting the enhanced susceptibility response as a result of the surface covering. Fourier transform infrared (FTIR) analysis provides the characteristic vibrations of Ca(3)(PO(4))(2) and the presence of the polymer surfactant on the nanoparticle surface. Moreover, the nanoparticles could be directly transferred to water and the aqueous dispersion-collection process of the nanoparticles was demonstrated for application readiness of such core-shell nanostructures in an aqueous medium. Thus, the construction of Fe(3)O(4) and Ca(3)(PO(4))(2) in the core-shell nanostructure has conspicuously led to enhanced performance and multi-functionalities, offering various possible applications of the nanoparticles.
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- 2010
- Full Text
- View/download PDF
31. Substrate effects on microstructure and magnetic properties of electrodeposited Co nanowire arrays
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Young Keun Kim, Jun Hua Wu, Young Dong Ko, Jiung Cho, Jin Seok Chung, and Ji Hyun Min
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Materials science ,business.industry ,Metallurgy ,Nanowire ,General Physics and Astronomy ,chemistry.chemical_element ,Substrate (electronics) ,Microstructure ,Nanocrystalline material ,Magnetic anisotropy ,chemistry ,Ferromagnetism ,Perpendicular ,Optoelectronics ,business ,Cobalt - Abstract
The effect of substrates on the microstructure and magnetic properties of electrodeposited Co nanowire arrays in porous anodic aluminum oxide membrane was investigated. It is found that the nanowires possess dominant (002) and (110) textures on the Co-coated nanocrystalline Finemet™ and Au substrates, respectively. Magnetic measurements show that the easy axis of the nanowire arrays switches from perpendicular to the wire axis on Au to parallel to the wire axis on the Co-coated nanocrystalline Finemet™ substrate.
- Published
- 2006
- Full Text
- View/download PDF
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