Ryo Asakura

Preparation of Fluorescent Poly(methyl methacrylate) Beads Hybridized with Y3Al5O12:Ce3+ Nanophosphor for Biological Application

Poly(methyl methacrylate) beads were hybridized with Y3Al5O12:Ce3+ nanoparticles through electrostatic interactions using the layer-by-layer adsorption technique to prepare fluorescent beads for biological application. The subsequent sequential adsorption of poly(sodium 4-styrenesulfonate) and poly(allylamine hydrochloride) onto the composite beads prevented the detachment of the Y3Al5O12:Ce3+ nanoparticles. The fluorescent beads were observed as tight dot plots by flowcytometry. Bovine serum albumin can be immobilized on the surface of the composite beads and tagged with a red dye through an antigen–antibody reaction. This result indicates that the composite beads are useful for bead assays such as flowcytometry.

Surface modification of YAG:Ce3+ nanoparticles by poly(acrylic acid) and their biological application

Yttrium aluminum garnet Y3Al5O12 (YAG):Ce3+ nanoparticles prepared by glycothermal method are modified with poly(acrylic acid) (PAA). This surface modification enables YAG:Ce3+ nanoparticles to be well dispersed in phosphate-buffered saline (PBS) without any serious aggregation. YAG:Ce3+ nanoparticles emit yellowish green light under the excitation of blue light. This fluorescent property does not change after the modification of PAA. Streptavidin (SA) is immobilized on the surface of PAA-modified YAG:Ce3+ nanoparticles by using carboxyl groups of PAA as cross-linking sites. We demonstrate the quantitative analysis of bovine serum albumin in PBS by SA-immobilized YAG:Ce3+ nanoparticles.

Glycothermal Synthesis and Magnetic Properties of YIG/YAG Nanoparticles

Yttrium aluminum garnet (YAG) nanoparticles of 14.5±3.2 nm in diameter are synthesized from yttrium acetate and aluminum isopropoxide in 1,4-butanediol by autoclave treatment at 300oC for 2h. Yttrium iron garnet (YIG) / YAG composite nanoparticles of 21.1±4.9 nm in diameter are synthesized from yttrium acetate and iron(III) acetylacetonate in 1,4-butanediol by autoclave treatment at 300oC for 2h using YAG nanoparticles as the seed. In contrast, YIG is not formed by the same procedure in the absence of the YAG seed. The saturation magnetizations of nanoparticles with different YIG/YAG ratios range from 11.9 to 17.8 emu/g. YIG/YAG nanoparticles dispersed in the agarose gel are observed by magnetic resonance imaging (MRI). The degree of the negative MRI contrast depends on the concentration of YIG/YAG nanoparticles.

Fluorescent and Magnetic Resonance Imaging by Rare Earth Doped Nanoparticles with Garnet Structure

Yb 3+ doped Y 3 Al 5 O 12 (YAG:Yb 3+ ) nanoparticles are prepared from yttrium acetate tetrahydrate, ytterbium acetate tetrahydrate and aluminum isopropoxide in 1,4-butanediol by autoclave treatment at 300 °C for 2 h. Moreover, Gd-YAG:Yb 3+ nanoparticles are prepared from the mixture of YAG:Yb 3+ colloidal solution and gadolinium acetate tetrahydrate by the same autoclave treatment as YAG:Yb 3+ . Properties of structure, near infrared photoluminescence and magnetic resonance contrast enhancement are characterized for as-prepared and calcined YAG:Yb 3+ and Gd-YAG:Yb 3+ nanoparticles.