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Fujii S.,Osaka Institute of Technology | Okada M.,Osaka Dental University | Nishimura T.,Osaka Institute of Technology | Sugimoto T.,Osaka Institute of Technology | And 5 more authors.
Composite Interfaces | Year: 2013

Hydroxyapatite (HAp) nanoparticle-coated poly(-caprolactone) (PCL) microspheres were fabricated via surfactant-free 'Pickering-type' emulsion solvent evaporation method in the absence of any molecular surfactants. HAp nanoparticles worked as an efficient stabilizer for dispersion of emulsions and microspheres. Optical microscopy, scanning electron microscopy, laser diffraction particle size analyzer, and elemental analysis were used to characterize the microspheres in terms of their size, dispersibility in aqueous media, morphology of the microspheres, and chemical compositions. The microsphere size and PCL/HAp weight ratio were successfully controlled by fabrication parameters (PCL concentration in the oil phase, HAp nanoparticle concentration in the aqueous phase, and homogenization rate): number-average diameter of the microspheres was systematically controlled over a wide range (9.2.25.1 μm) and PCL/HAp weight ratio was controlled to be between 74.0/26.0 and 99.8/0.2. Laser diffraction and optical microscopy studies of dilute aqueous dispersions indicate that the polymer microspheres disperse stably before and after evaporation of the oil. Potential applications for these HAp-coated PCL microspheres include carriers for cell delivery in tissue engineering and for sustained release of therapeutics. © 2013 Taylor & Francis. Source


Fujii S.,Osaka Institute of Technology | Okada M.,Osaka Dental University | Nishimura T.,Osaka Institute of Technology | Maeda H.,Osaka Institute of Technology | And 5 more authors.
Journal of Colloid and Interface Science | Year: 2012

Hydroxyapatite (HAp) nanoparticle-armored poly(ε-caprolactone) (PCL) microspheres were fabricated via a " Pickering-type" emulsion solvent evaporation method in the absence of any molecular surfactants. It was clarified that the interaction between carbonyl/carboxylic acid groups of PCL and the HAp nanoparticles at an oil-water interface played a crucial role in the preparation of the stable Pickering-type emulsions and the HAp nanoparticle-armored microspheres. The HAp nanoparticle-armored PCL microspheres were characterized in terms of size, size distribution, morphology, and chemical compositions using scanning electron microscopy, laser diffraction, energy dispersive X-ray microanalysis, and thermogravimetric analysis. The presence of HAp nanoparticles at the surface of the microspheres was confirmed by scanning electron microscopy and energy dispersive X-ray microanalysis. Pyrolysis of the PCL cores led to the formation of the corresponding HAp hollow microcapsules. © 2012 Elsevier Inc. Source


Hamasaki H.,Osaka Institute of Technology | Kanadani H.,Osaka Institute of Technology | Nakamura Y.,Osaka Institute of Technology | Nakamura Y.,Nanomaterials Microdevices Research Center | Fujii S.,Osaka Institute of Technology
Chemistry Letters | Year: 2012

Aqueous chemical oxidative polymerization of pyrrole using PdCl 2 oxidant was conducted in the presence of cetyltrimethylammonium bromide in order to synthesize polypyrrole-palladium (PPy-Pd) nanocomposite in one step. Interestingly, the PPy-Pd nanocomposite was synthesized with fibrous morphology. Transmission electron microscopy studies confirmed that Pd and PPy components formed composite in nanometer dimensions. © 2012 The Chemical Society of Japan. Source


Hamasaki H.,Osaka Institute of Technology | Maekawa Y.,Osaka Institute of Technology | Matsuzawa S.,Osaka Institute of Technology | Ohtaka A.,Osaka Institute of Technology | And 3 more authors.
Chemistry Letters | Year: 2012

Poly(3,4-ethylenedioxythiophene)palladium nanocomposite was deposited in situ from water-based solution onto micrometer-sized polystyrene particles. The resulting composite particles were extensively characterized with respect to particle size and size distribution, morphology, and chemical compositions. © 2012 The Chemical Society of Japan. Source

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