C. S. Kuroda

Magnetic carriers of iron nanoparticles coated with a functional polymer for high throughput bioscreening

We synthesized iron nanoparticles, 15–20 nm in size, having saturation magnetization, Ms, of 170emu∕g. They were embedded in copolymer beads of styrene (St) and glycidyl methacrylate (GMA), which were coated with poly-GMA by seed polymerization. The resultant Fe∕St-GMA/GMA beads had diameters of 100–200 nm and Ms of 60emu∕g. By coating with poly-GMA, the zeta potential of the beads changed from −93.7 to −54.8mV, as measured by an electrophoresis method. This facilitated (as revealed by gel electrophoresis method) nonspecific protein adsorption suppression, a requisite for nanoparticles to be applied to carriers for bioscreening.

Magneto-optical properties and morphology of particulate film consisting of Bi-YIG coprecipitated particles

Abstract Magneto-optical properties of particulate films containing bismuth yttrium iron garnet small particles were investigated. The small particles with different crystallite sizes were prepared by coprecipitation method and changing heat treatment temperatures from 600° to 725°C. The crystallite size of the particle increased with raising heat treatment temperature and the saturation magnetization showed a maximum for the particles heated at 700°C. Oscillatory behavior of the Faraday rotation of the particulate film was also observed as a function of the heat treatment temperature. This can be well characterized by the magnetization and the absorption coefficient that abruptly increases around 650°C. The increase in the absorption coefficient was due to the change in the size of constituent garnet particles in the film. The magneto-optical properties and the morphology of the particulate films were examined in detail.

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

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

Styrene-coated iron nanobeads for medical use

Spherical iron nanoparticles with a diameter of 10 nm were synthesized using a water in oil reverse micelle systems. The particles were encapsulated in styrene polymer by an emulsion polymerization method. The resulting beads were 150/spl plusmn/50 nm in diameter, having a saturation magnetization of 23.5 emu/g. The styrene-coated iron particles exhibited superparamagnetism, as measured by Mo/spl uml/ssbauer spectroscopy, and dispersed well in water. The saturation magnetization was higher than reported for commercially available polymer-coated micron sized beads.