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Katsushika-ku, Japan

Hashimoto M.,Health Sciences University of Hokkaido | Toshima H.,Health Sciences University of Hokkaido | Yonezawa T.,Hokkaido University | Kawai K.,Miyoshi Oil and Fat Co. | And 3 more authors.
Journal of Biomedical Materials Research - Part A

Nanometals are currently receiving considerable attention for industrial and biomedical applications, but their potentially hazardous and toxic effects have not been extensively studied. This study evaluated the biological responses of novel water-dispersible gold (Au-NPs) and silver nanoparticles (Ag-NPs) stabilized by Au-C or Ag-C σ-bonds in cultured macrophages (RAW264.7), via analysis of the cell viability, the integrity of the plasma membrane, and the inflammatory and morphological properties. The cultured RAW264.7 was exposed to metal-NPs at various concentrations. The Ag-NPs showed cytotoxicity at high NP concentrations, but the cytotoxic effects of the Au-NPs were smaller than those of the Ag-NPs. For the microscopic analysis, both types of particles were internalized into cells, the morphological changes in the cells which manifested as an expansion of the vesicles' volume, were smaller for the Au-NPs compared with the Ag-NPs. For the Ag-NPs, the endocytosis abilities of the macrophages might have induced harmful effects, because of the expansion of the cell vesicles. Although an inflammatory response was observed for both the Au- and Ag-NPs, the harmful effects of the Au-NPs were smaller than those of the Ag-NPs, with minor morphological changes observed even after internalization of the NPs into the cells. © 2013 Society of Plastics Engineers. Source

Sakai K.,Tokyo University of Science | Umemoto N.,Tokyo University of Science | Matsuda W.,Tokyo University of Science | Takamatsu Y.,Miyoshi Oil and Fat Co. | And 3 more authors.
Journal of Oleo Science

Anionic gemini surfactants with carboxylic acid headgroups have been synthesized from oleic acid. The hydrocarbon chain is covalently bound to the terminal carbonyl group of oleic acid via an ester bond, and the carboxylic acid headgroups are introduced to the cis double bond of oleic acid via disuccinyl units. The surfactants exhibit pH-dependent protonation-deprotonation behavior in aqueous solutions. In alkaline solutions (pH 9 in the presence of 10 mmol dm-3 NaCl as the background electrolyte, the surfactants can lower the surface tension as well as form molecular assemblies, even in the region of low surfactant concentrations. Under acidic (pH 3 or neutral (pH 6-7 conditions, the surfactants are intrinsically insoluble in aqueous media and form a monolayer at the air/water interface. In this study, we have investigated physicochemical properties such as the function of the hydrocarbon chain length by means of static surface tension, pyrene fluorescence, dynamic light scattering, surface pressure-area isotherms, and infrared external reflection measurements. © 2011 by Japan Oil Chemists' Society. Source

Abe S.,Hokkaido University | Hyono A.,Hokkaido University | Kawai K.,Hokkaido University | Kawai K.,Miyoshi Oil and Fat Co. | Yonezawa T.,Hokkaido University
Journal of Nanoscience and Nanotechnology

In this study, we investigated conductivity preparation for scanning electron microscope (SEM) observation that used novel asymmetrical choline-type room temperature ionic liquids (RTIL). By immersion in only an RTIL solution, clear SEM images of several types of biological samples were successfully observed. In addition, we could visualize protozoans using RTILs without any dilution. These results suggested that the asymmetrical choline-type RTILs used in this study are suitable for visualizing of biological samples by SEM. Treatment without the need for dilution can obviate the need for adjusting the RTIL concentration and provide for a rapid and easy conductivity treatment for insulating samples. Copyright © 2014 American Scientific Publishers. Source

Shishino Y.,University of Tokyo | Yonezawa T.,Hokkaido University | Kawai K.,Hokkaido University | Kawai K.,Miyoshi Oil and Fat Co. | Nishihara H.,University of Tokyo
Chemical Communications

Water-soluble luminescent AuNPs of 1.3 ± 0.3 nm in diameter with a large Stokes shift were facilely synthesized by a new molten matrix sputtering (MMS) method. © 2010 The Royal Society of Chemistry. Source

Kawai K.,Hokkaido University | Kawai K.,Miyoshi Oil and Fat Co. | Kaneko K.,Miyoshi Oil and Fat Co. | Yonezawa T.,Hokkaido University

This Letter examines the relationship between the structures of ionic liquids and their water-solubility or osmotic pressure with a number of synthesized quaternary ammonium type ionic liquids and organic salts containing a hydroxyl group as hydrophilic substituted groups on ammonium group cations, and bromide or methylsulfonate as anions. The study found a linear relation between the amount and osmotic pressure of the water-soluble ionic liquids synthesized here, strongly indicating that these water-soluble ionic liquids are perfectly ionized in water like inorganic salts with small diameter ions. © 2011 American Chemical Society. Source

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