Shinji Takeoka

Photoluminescence (PL) from surface-oxidized Si nanocrystals (nc-Si) was studied as a function of the size. The size of nc-Si was comparable with or larger than the Bohr radius of free excitons in bulk Si crystal (5 nm). In contrast to smaller surface-oxidized nc-Si (typically as small as a few nanometers in diameter), these relatively large nc-Si exhibited PL properties with strong size dependence. A high-energy shift of the PL peak from the vicinity of the bulk band gap to the visible region w

We have succeeded in observing the size dependent photoluminescence (PL) from Ge nanocrystals (nc-Ge) with 0.9--5.3 nm in average diameter ${(d}_{\mathrm{ave}})$ in the near-infrared region. The nc-Ge were fabricated by rf cosputtering of Ge and ${\mathrm{SiO}}_{2}$ and post annealing at $800\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}.$ It was found that the sample with ${d}_{\mathrm{ave}}=5.3\mathrm{nm}$ shows a PL peak at about 0.88 eV. With decreasing the size, the PL peak shifted to higher

Abstract Recent developments in nanotechnology have led to a method for producing free‐standing polymer nanosheets as a macromolecular organization. Compared with bulk films, the large aspect ratio of such nanosheets leads to unique physical properties, such as transparency, noncovalent adhesion, and high flexibility. Here, a biomedical application of polymer nanosheets consisting of biocompatible and biodegradable polysaccharides is reported. Micro‐scratch and bulge tests indicate that the nano

A free-standing biodegradable nanosheet composed of poly(L-lactic acid) (PLLA) was shown to have excellent sealing efficacy for a gastric incision as a novel wound dressing material that did not require adhesive agents, and the PLLA nanosheet-induced wound repair showed neither scars nor tissue adhesion. This material may, therefore, be an ideal alternative to conventional tissue repairing procedures using suture/ligation in surgery.

A free-standing polysaccharide nanosheet prepared by using a spin-coating-assisted layer-by-layer method is transferred from silicone rubber onto human skin (see figure) by fabricating a three-layered ‘nano-adhesive plaster' involving a water-soluble sacrificial layer. By using this novel technique, conventional ultrathin films can be made without the need for a solid substrate.

Mitochondrial thermodynamics is the key to understand cellular activities related to homeostasis and energy balance. Here, we report the first ratiometric fluorescent molecular probe (Mito-RTP) that is selectively localized in the mitochondria and visualize the temperature. We confirmed that Mito-RTP could work as a ratiometric thermometer in a cuvette and living cells.

Photoluminescence (PL) from ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ alloy nanocrystals $(\mathrm{nc}\ensuremath{-}{\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x})$ as small as 4--5 nm in diameter was studied as a function of the Ge content. The $\mathrm{nc}\ensuremath{-}{\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ samples were fabricated by the cosputtering of Si, Ge, and ${\mathrm{SiO}}_{2}$ and postannealing at $1100\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}.$ High-resol

Freestanding poly(L-lactic acid) (PLLA) nanosheets are mass-produced by a simple combination of a spin-coating-assisted multi-layering process and a peeling technique. The resulting PLLA nanosheets are fragmented by homogenization and then reconstructed into a "patchwork" sheet on various surfaces without any adhesive reagents. The patchwork is shown to offer excellent protection against burn wound infection with Pseudomonas aeruginosa, and may therefore be an alternative to conventional burn th

Thermoplastic elastomers are attractive materials because of the drastic changes in their physical properties above and below the glass transition temperature (T_g). In this paper, we report that free-standing polystyrene (PS, T_g: 100 °C) and polystyrene-polybutadiene-polystyrene triblock copolymer (SBS, T_g: -70 °C) thin films with a thickness of hundreds of nanometers were prepared by a gravure coating method. Among the mechanical properties of these thin films d

Hemoglobin vesicles, which encapsulated concentrated hemoglobin (Hb) with a bilayer of dipalmitoylphosphatidylcholine/cholesterol/palmitic acid, were prepared under various preparation conditions in order to decrease the number of bilayers (n) constructing the vesicle and increase the Hb concentration in the interior of the vesicle ([Hb]in). n decreased when the surface potential of the bilayer became more negative because of the electrostatic repulsion between the bilayers, while with a changin

We report a mitochondrial targeted redox probe (MitoRP) that comprises a nitroxide radical (TEMPO) moiety and coumarin 343. Using isolated mitochondria in the presence/absence of substrates and inhibitors of oxidative phosphorylation, we demonstrated that MitoRP is a useful probe to monitor the electron flow associated with complex I.