Hironori Iida

Biosensing by optical waveguide spectroscopy based on localized surface plasmon resonance of gold nanoparticles used as a probe or as a label

The application of localized surface plasmon resonance (LSPR) of gold nanoparticles for the detection of biotin-streptavidin binding, as a typical biological reaction, was investigated by using optical waveguide spectroscopy, and two different modes for the use of gold nanoparticles, one as a probe and the other as a label were compared with each other. The combination with optical waveguide spectroscopy was found to bring about a high sensitivity for the biomolecular detection system using LSPR of gold nanoparticles in both modes. In particular, the mode using gold nanoparticles as a label was demonstrated to be of advantage to devising proper procedures for using nanoparticles and evaluating actual response relevant to the phenomenon concerned, and thus to sensitive detection.

Preparation of human immune effector T cells containing iron-oxide nanoparticles.

Preparation of human immune T cells containing iron‐oxide nanoparticles was carried out for the development of magnetically mediated immunotherapy. Peripheral blood lymphocytes (PBLs) after the incubation with magnetite nanoparticles were found to contain measurable ferric ions, which suggested the incorporation of magnetite nanoparticles. Transmission electron microscopic (TEM) study indicated that the incorporation of magnetite nanoparticles was mediated by endocytosis of PBLs. Furthermore, the effects of dosages and diameter of magnetite nanoparticles on the magnetite incorporation were investigated, and it was demonstrated that the increase in dosage promoted the incorporation of nanoparticles and the uptake into PBLs was more effective for magnetite nanoparticles, which formed smaller aggregations in medium. Finally, the demonstration of magnetite incorporation into enriched T cells and tumor antigen‐specific cytotoxic T lymphocyte (CTL) line promises the achievement of magnetically mediated immunotherapy with tumor‐specific CTLs containing magnetic nanoparticles. Biotechnol. Bioeng.

New trends in nanoparticles: syntheses and their applications to fuel cells, health care, and magnetic storage

This paper reviews important research on chemical and electrochemi- cal synthesis and application of nanoparticles, especially our recent results in this field: (i) catalytic metal nanoparticles for micro-fuel cells, (ii) magnetic oxide nanoparticles for drug delivery systems, and (iii) magnetic metal nanoparticles for magnetic recording media. To fulfill the requirements of each application, we chose and modified those synthetic methods for obtaining suitable properties, e.g., mor - phology, catalytic activity, and magnetic properties. (i) For micro-fuel cells, elec- trodeposition is attractive because of its selective deposition onto current collectors and possible elimination of an annealing process. As a result, we have successfully synthesized Pt, PtRu alloy, and PdCo alloy, which consisted of dendritic structures macroscopically and of interconnected nanoparticles microscopically. (ii) For drug delivery systems, since magnetic nanoparticles should possess ferromagnetism, be dispersible in water, and be nontoxic, Fe3O4 nanoparticles synthesized by hydroly- sis in aqueous media are suitable. As a result, we have successfully controlled the size (10-40 nm in diameter) and the magnetic properties of Fe3O4 nanoparticles by means of adjusting the molar ratio of ferrous to ferric ions in the precursor solution. (iii) For magnetic recording materials, since magnetic nanoparticles should possess high coercivity, a controlled shape, and a uniform small size, we have modified a chemical method for synthesizing FePt by adjusting the growth temperature. As a result, we have succeeded in synthesizing FePt nanoparticles with a controlled shape (cubic) and a uniform size (ca. 5.6 nm).