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Kawasaki, Japan

Takahashi H.,Kyoto University | Tahara Y.,JST ERATO | Sawada S.-I.,Kyoto University | Akiyoshi K.,Kyoto University
Biomaterials Science | Year: 2013

A new intracellular protein delivery nanocarrier with protein stabilizing ability was constructed of cationic amphiphilic polysaccharide nanoballs. Amphiphilic enzymatically synthesized glycogen (ESG) made by modification of hydrophobic cholesterol groups to ESG, which is a monodispersed spherical hyper-branched polysaccharide nanoparticle, formed self-assembled cluster nanogels (CHESG nanogels) in water. Cationic amphiphilic ESG derivatives where the diethylethylenediamine (DEAE) group was introduced into CHESG (CHESG-DEAE) were positively charged, monodispersed, and non-aggregated amphiphilic nanoballs with hydrophobic nanodomains provided by the cholesterol groups. The CHESG-DEAE strongly interacted with proteins and stabilized them against thermal denaturation. Furthermore, the cationic CHESG effectively internalized a number of proteins into HeLa cells. This cationic ESG nanoball-based material shows great potential as an effective protein delivery nanocarrier. © 2013 The Royal Society of Chemistry.

Iwasa T.,JST ERATO | Nakajima A.,Keio University
Chemical Physics Letters | Year: 2013

We present the physicochemical properties for the lowest-energy isomer of a boron-doped aluminum cluster of B2Al21-. The isomer was obtained by basin-hopping minimization based on the density functional theory, starting from a face-sharing bi-icosahedral structure in which two boron atoms were endohedrally doped to each icosahedron. The lowest-energy isomer is a triangular form in which an aluminum cage encapsulates two boron atoms endohedrally. The electronic structure was analyzed by projecting Kohn-Sham orbitals onto the spherical harmonics; occupied and unoccupied frontier orbitals are dominantly G- and H-symmetries, respectively. Optical absorption is mainly assigned to G to H transitions. © 2013 Elsevier B.V. All rights reserved.

Goretta S.A.,Osaka University | Kinoshita M.,JST ERATO | Mori S.,Osaka University | Tsuchikawa H.,Osaka University | And 2 more authors.
Bioorganic and Medicinal Chemistry | Year: 2012

Sphingomyelin (SM) and cholesterol form microdomains called lipid rafts in cellular membranes. To develop a versatile fluorescent lipid probe, chemical modifications to both the hydrophobic and hydrophilic portions of SM are essential. Few reports describing SM probes with a fluorophore at the polar head group have been published. This study examined the effect of substitution on an ammonium moiety of SM on the membrane properties of SM. Two SM analogs with small propargyl and allyl groups on the quaternary nitrogen atom were synthesized and subjected to analysis using differential scanning calorimetry, fluorescent anisotropy, detergent solubilization, surface pressure, and density measurements. Results demonstrated that the two SM analogs retained the membrane properties of SM, including formation of an ordered phase and the ability to interact with cholesterol. A dansyl-substituted SM was prepared for fluorescent measurements. Dansyl-SM showed less of a propensity to form microdomains. These findings imply the potential application of N-substituted SMs as a raft-specific molecular probe. © 2012 Elsevier Ltd. All rights reserved.

Kazi R.H.,JST ERATO | Kazi R.H.,National University of Singapore | Igarashi T.,JST ERATO | Igarashi T.,University of Tokyo | And 2 more authors.
Conference on Human Factors in Computing Systems - Proceedings | Year: 2012

Vignette is an interactive system that facilitates texture creation in pen-and-ink illustrations. Unlike existing systems, Vignette preserves illustrators' workflow and style: users draw a fraction of a texture and use gestures to automatically fill regions with the texture. We currently support both 1D and 2D synthesis with stitching. Our system also has interactive refinement and editing capabilities to provide a higher level texture control, which helps artists achieve their desired vision. A user study with professional artists shows that Vignette makes the process of illustration more enjoyable and that first time users can create rich textures from scratch within minutes. Copyright 2011 ACM.

Sugiyama A.,JST ERATO | Nakajima A.,JST ERATO | Nakajima A.,Keio University
Zeitschrift fur Physikalische Chemie | Year: 2014

We have used time-resolved imaging to examine the effect of incident radiation wavelength in the range 2.75-3.75 μm on the shattering of water microdroplets by single and dual lasers. Dye sensitization of microdroplets was induced by using the water-soluble dye sulforhodamine G; this enabled us to observe both the forward and backward components of fragmented droplets and splashes. Compared with employing a single IR laser, simultaneous illumination by two IR lasers can effectively compress the spatial distribution of small fragments around the absorption maximum for the OH-stretching vibration of liquid water (y=2.75-3.25 μm). Scattering and compression of the fragmented microdroplets after single and dual IR laser irradiation can be explained by conservation of momentum.

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