Noboru Ohta

Japan Synchrotron Radiation Research Institute (JASRI), Tatsuno, Hyōgo, Japan

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Publications (45)122.99 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The chain stiffness and local chain conformation of atactic poly(α-methylene-γ-butyrolactone) (PMBL), which is a side chain cyclic structural analog of poly(methyl methacrylate) (PMMA), with a weight-average molecular weight (Mw) ranging from 2.8 × 103 to 2.6 × 106 in N,N-dimethylformamide (DMF) and γ-butyrolactone (GBL) were characterized by size exclusion chromatography with a multi-angle light-scattering detector (SEC-MALS) and synchrotron radiation small-angle X-ray scattering (SAXS). Based on the Kratky-Porod worm-like chain model, the scattering functions and the Mw dependence of z-average root-mean-square radius of gyration z1/2 yielded the Kuhn segment lengths λ−1, the diameter of the PMBL chains d, and the excluded-volume strengths in DMF and GBL. The local conformation of atactic PMBL in DMF and GBL were slightly larger than those of atactic PMMA, due to the presence of the conformationally rigid lactone ring structure.
    Polymer. 10/2014;
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    ABSTRACT: We observed the dynamic three-dimensional (3D) single molecule behaviour of acetylcholine-binding protein (AChBP) and nicotinic acetylcholine receptor (nAChR) using a single molecule tracking technique, diffracted X-ray tracking (DXT) with atomic scale and 100 μs time resolution. We found that the combined tilting and twisting motions of the proteins were enhanced upon acetylcholine (ACh) binding. We present the internal motion maps of AChBP and nAChR in the presence of either ACh or α-bungarotoxin (αBtx), with views from two rotational axes. Our findings indicate that specific motion patterns represented as biaxial angular motion maps are associated with channel function in real time and on an atomic scale.
    Sci. Rep. 09/2014; 4.
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    ABSTRACT: We carried out synchrotron X-ray scattering experiments from four DNA supermolecules designed to form tetrapod shapes; these supermolecules had different sequences but identical numbers of total base pairs and each contained an immunostimulatory CpG motif. We confirmed that the supermolecules did indeed form the expected tetrapod shape. The sample that had the largest radius of gyration (Rg) induced the most cytokine secretion from cultured immune cells Structural analysis in combination with a rigid tetrapod model and an atomic scale DNA model revealed that the larger Rg can be ascribed to dissociation of the DNA double strands in the central connecting portion of the DNA tetrapod. This finding suggests that the biological activity is related to the ease with which single DNA strands can be formed.
    The journal of physical chemistry. B. 08/2014;
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    ABSTRACT: We synthesized new calix[4]arene-based lipids, denoted by CPCaLn, bearing choline phosphate (CP) group which is inverse phosphoryl choline (PC) structure. Small-angle X-ray scattering and multi-angle light scattering coupled with field flow fractionation showed that these lipids form monodisperse micelles with a fixed aggregation number and diameters of 1.9 and 2.6 nm for lipids bearing C3 and C6 alkyl tails, respectively. Furthermore, when CPCaLn was mixed with the fluorescein isothiocyanate (FITC)-bearing lipids and added to cells, the strong fluorescence was observed at 37 °C, but not at 4 °C, indicating that the micelles were taken up by the cells through endocytosis. Recent studies have shown that replacement of polymer-attached PC groups with CP groups markedly promotes cellular uptake, even though the surface charge is neutral. On the basis of the idea, CPCaLn micelles interacted with cells in the same way, suggesting that the micelles bearing CP groups are expected to use as carriers in drug delivery system.
    Soft Matter 08/2014; · 4.15 Impact Factor
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    ABSTRACT: For small-angle X-ray scattering (SAXS) in solution, absolute intensity calibration is an important step to estimate the number of electrons of the sample. In this study, the excess scattering length of 1-bromododecane dispersed in dodecane was determined using that of 1-chlorododecane in the same solvent. The deviation of the experimental values from theoretical calculations obtained using atomic factors was around 1%. It is suggested that the 1-chlorododecane–dodecane system constitutes a new calibration approach that is applicable to various materials over a large energy range generally used in SAXS measurements, and could be less complex and more reliable than conventional methods.
    Journal of Applied Crystallography 04/2014; 47(2). · 3.34 Impact Factor
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    ABSTRACT: The simultaneous measurement of Fourier transform infrared (FTIR) transmission spectra and 2-dimensional wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) patterns has been performed successfully to investigate the hierarchical structure changes occurring in the stress-induced phase transition phenomenon of uniaxially oriented poly(tetramethylene terephthalate) film. The molar fraction of the β-crystal form, evaluated from the IR and WAXD data analyses, increased steeply in the plateru region of the stress–strain curve as already known well. The 2D SAXS data have revealed the remarkable and reversible change in the stacked lamellar structure just after the α-to-β phase transition was completed, where the tilting angle of the stacked lamellae measured from the draw axis of the oriented sample became zero, and the lamellar thickness increased due to the inclusion of amorphous region located in the boundary part of the crystalline lamellae. In parallel, the X-ray reflection spots in a wider diffraction angle region became diffuse in the observed WAXD pattern of the β form, indicating the packing disorder of the mechanically stressed chains. In this way, the simultaneous combination of the 3 different types of equipments has allowed us to deduce the detailed structural change from the various levels: the stress-induced α–β transition was found to occur not only with the remarkable changes in the molecular chain conformation and chain packing mode in the crystal lattice, but also with the large and reversible change in the lamellar stacking structure. The stress-induced changes in lamellar thickness and long period were simulated using a mechanical model with these hierarchical structure changes taken into account, giving relatively good reproduction of the observed data.
    Macromolecules 03/2014; 47(6):2052–2061. · 5.93 Impact Factor
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    ABSTRACT: A novel calix[4]arene amphiphilic molecule, denoted by CCaL3, was synthesized and found to form a spherical micelle consisting of 12 molecules at low pH in aqueous solution. Furthermore, uniform Au nanoparticles with 2.0 nm in diameter were synthesized in aqueous solution on the template consisting of the four cysteines of the upper rim of CCaL3. Asymmetric field flow fractionation coupled with light scattering showed that there was no dispersity in the CCaL3 micellar aggregation number. When AuCl4- ions were added into the CCaL3 micelle solution, induced circular dichroism (ICD) appeared, indicating appearance of the structural chirality of the CCaL3/AuCl4- complex. A combination of electron microscopy and small-angle X-ray scattering showed that helically coiled bilayer sheets were formed upon addition of AuCl4-. Subsequent reduction with the amine of cysteine moieties led to uniform Au nanoparticles formation with 2.0 nm in diameter on the micellar plate surface. The nanoparticle size was almost equal to the size of cavity constructed by the four cysteines on the calix[4]arene upper rim, indicating that the growth of Au nanoparticles was spatially controlled by the host-guest interaction between the cysteines and Au.
    Langmuir 10/2013; · 4.38 Impact Factor
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    ABSTRACT: Diffracted X-ray tracking (DXT) enables the tilting and twisting motions of single protein molecules to be monitored with micro- to milliradian resolution using a highly brilliant X-ray source with a wide energy bandwidth. We have developed a technique to monitor single molecules using gold nanocrystals attached to individual protein molecules using the BL28B2 beamline at SPring-8. In this paper we present the installation of a single toroidal X-ray mirror at BL28B2 to focus X-rays in an energy range of 10-20 keV (△E/E = 82% for an X-ray with a wide energy bandwidth). With this beamline we tracked diffraction spots from gold nanocrystals over a wide angle range than that using quasi-monochromatic X-rays. Application of the wide angle DXT technique to biological systems enabled us to observe the on-site motions of single protein molecules that have been functionalized in vivo. We further extend the capability of DXT by observing the fractional tilting and twisting motions of inner proteins under various conditions. As a proof of this methodology and to determine instrumental performance the intramolecular motions of a human serum albumin complex with 2-anthracenecarboxylic acid was investigated using the BL28B2 beamline. The random tilting and twisting intramolecular motions are shown to be directly linked to the movement of individual protein molecules in the buffer solution.
    The Review of scientific instruments 10/2013; 84(10):103701. · 1.52 Impact Factor
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    ABSTRACT: We investigated the molecular aggregation states, mechanical properties, and biodegradability of environmentally benign segmented polyurethane(urea)s [SPU(U)s], which contained bio-based monomers of an α-amino acid lysine-based diisocyanate (LDI). The SPU(U)s consisted of an aliphatic diisocyanate (LDI or 1,4-butanediisocyanate (BDI)), a chain extender (1,4-butanediamine (BDA) or 1,4-butanediol (BDO)), and a poly-ε-caprolactone (PCL) segment. Four SPU(U)s, LDI–BDA, LDI–BDO, BDI–BDA, and BDI–BDO, were prepared by a standard two-step prepolymer method. Fourier transformed infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and small-angle X-ray scattering (SAXS) measurement indicated that the LDI-series SPU(U)s formed weakly aggregated hard segment domains, which readily dissociated under mechanical deformation and heating. The diamine chain extender, BDA, enhanced the stability of the hard segment domains, and the BDA-series SPU(U)s exhibited better mechanical properties than the BDO-series. The LDI-series SPU(U)s have notable biodegradability, and the BDI-based hard segments delayed the degradation rate because of the strongly segregated hard segment.
    Polym. Chem. 06/2013; 4(13):3735-3743.
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    ABSTRACT: A series of poly[2-(methacryloyloxy)ethyltrimethylammonium chloride] (PMTAC) in aqueous NaCl solutions with a weight-average molecular weight (Mw) of between 6.0 × 103 and 1.5 × 105 were characterized by synchrotron radiation small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) measurements at 298 K. The hydrodynamic radius (RH) of PMTAC initially decreased with increasing salt concentration (Cs) and then leveled off at Cs = 0.5–1.0 M. The values of z-average root-mean-square radius of gyration (S2z1/2) simply increased with a decrease in Cs for Mw > 2 × 104 g/mol. In contrast, the values of S2z1/2 for Mw < 2 × 104 g/mol increased with an increase in Cs probably because of a change in local conformation of PMTAC chain. To study local chain conformation of PMTAC, scattering functions and Mw dependences of S2z1/2 and RH for PMTAC were analyzed in terms of the helical wormlike chain (HW) model which is a simple continuous elastic wire model with bending and torsional energies. The characteristic helix of the HW model in potential energy minimum for PMTAC clearly indicates that the local conformation is strongly influenced by the ionic strength of the solution.
    Macromolecules 05/2013; 46(10):4081-4088. · 5.93 Impact Factor
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    ABSTRACT: This work demonstrates the anomalous crystal growth of isotactic polystyrene (iPS) in nanorod arrays with different rod sizes. At the bottom of the nanorods, the crystals in bulk film grow into nanorods along either the [110] or [100] direction parallel to the rod axis. On the top side of the nanorods, the polymer exhibits different orientations corresponding to weak or strong confinement. In the weaker confinement (bigger nanorods of 300 nm diameter), the crystals grow with the [100] direction along the nanorod, which is similar to the crystals developed in the radial of spherulite. In the stronger confinement (smaller nanorods of 65 nm diameter), the splaying of crystals in the rod is significantly suppressed, and the preferred growth direction of iPS crystals is kept in either the [110] or [100] direction. The precise control of polymer crystal orientation and crystallinity at a local scale opens important perspectives for the design of one-dimensional nanomaterials whose performance depends on the anisotropic crystal properties.
    ACS Macro Letters. 04/2013; 2(5):414.
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    ABSTRACT: Preparation of strong fiber with ultrahigh strength and modus is a dream of polymer scientists and engineers. It is believed that a shish-kebab is the structure origin of the ultrahigh strength and modulus fiber. This article presents our investigation on the inner structure of shish-kebab precursor of isotactic polystyrene in μm scale formed by shear flow above the nominal melting temperature Tm using microbeam wide- and small-angle X-ray scattering (WAXS and SAXS). The microbeam WAXS experiments indicated that the precursor included crystallites with degree of crystallinity of 0.15%, which had higher melting temperature than normal lamellar crystals, meaning that its size (the length) was longer in the c-axis of crystals than the normal lamellar crystals. The microbeam SAXS experiments confirmed that approximately 1% of the crystallites in the precursor were rather long in the direction of c-axis. It is expected that such crystallites work as an initiator of a shish when it is below Tm.
    Macromolecules 04/2013; 46(8):3031-3036. · 5.93 Impact Factor
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    ABSTRACT: The determination of liquid structures under nanometer-scale confinement is important in advanced sciences and technologies. Synchrotron X-ray diffraction measurement was performed to investigate the structure of a smectic liquid crystal, 4-cyano-4'-octylbiphenyl (8CB), nanofilm (thickness: 1.7 ± 0.5 nm) confined between mica surfaces. A diffraction peak at q = 1.99 nm-1, corresponding to the lamellar spacing of 8CB, appeared immediately after 8CB was injected between the surfaces. This diffraction peak gradually decreased with time, indicating the structural change in 8CB from the ordered to the disordered state. The relaxation time was ca. 60 min and the diffraction peak almost disappeared at 100 min after 8CB injection. We could directly monitor the time course of the structural change in the smectic liquid crystal under molecular-scale confinement.
    Japanese Journal of Applied Physics 03/2013; 52(3):5002-. · 1.07 Impact Factor
  • SPring-8/SACLA Research Report. 02/2013; 1(1):1.
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    ABSTRACT: Polymeric micelles have been extensively studied as nanoscale drug carriers. Knowing the inner structure of polymeric micelles that encapsulate hydrophobic drugs is important to design effective carriers. In our study, the hydrophobic compound tetrabromocathecol (TBC) was chosen as a drug-equivalent model molecule. The bromine atoms in TBC act as probes in anomalous small-angle X-ray scattering (ASAXS) allowing for its localization in the polymeric micelles whose shape and size were determined by normal small-angle X-ray scattering (SAXS). Light scattering measurements coupled with field flow fractionation were also carried out to determine the aggregation number of micelles. A core-corona spherical model was used to explain the shape of the micelles, while the distribution of bromine atoms was explained with a hard-sphere model. Interestingly, the radius of the spherical region populated with bromine atoms was larger than the one of the sphere corresponding to the hydrophobic core of the micelle. This result suggests that the TBC molecules infiltrate the PEG hydrophilic domain in the vicinity of the core/shell interface. The results of light scattering and SAXS indicate that the PEG chains at the shell region are densely packed, and thus the PEG domain close to the interface has enough hydrophobicity to tolerate the presence of hydrophobic compounds.
    Journal of the American Chemical Society 01/2013; · 10.68 Impact Factor
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    ABSTRACT: Based on efforts to develop synthetic materials with novel properties similar to the ingenious mussel adhesive, we present a structural study of gels with different cross-linking approaches, using a catechol-bearing polystyrene system. Prior studies have shown that catechol affords a dual cross-linking system based on Fe3+–catechol complexes and oxidative coupling. In this study, the structures of gels with different cross-linking ratios were investigated by field-emission scanning electron microscopy (FE-SEM), small angle X-ray scattering (SAXS), Raman spectroscopy, and dynamic viscoelastic measurements. These results revealed that Fe3+–catechol cross-linking leads to a more compact structure, which increased the gel rigidity. In addition, Fe3+–catechol cross-links could be removed from the hybrid cross-linking system by an acidifying process, yielding a catechol–catechol cross-linked gel with stable covalent bonds. A structure in which a continuous network of loosely folded poly(styrene-co-DOPMAm) chains is combined, with a cross-linking density varying from high (coordinative) to low (covalent), was achieved by balancing both oxidation and coordination. The work presented here will provide inspiration for those designing new classes of synthetic materials with advanced properties, biomimicking extensible byssal threads.
    Soft Matter 01/2013; 9(6):1967-1974. · 4.15 Impact Factor
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    ABSTRACT: The development of macroscopic nanofiber orientation and microscopic crystallite and molecular chain orientation have been investigated during uniaxial stretching of electrospun poly(vinyl alcohol) (PVA) non-woven nanofiber mats. Scanning electron microscopy and stress-strain/small-angle X-ray scattering show that the macroscopic nanofiber orientation significantly increases during the initial stage of deformation, and approaches a plateau on the way of stretching. Detailed analyses of the stress-strain/wide-angle X-ray diffraction measurement and polarized Fourier transform infrared spectroscopy indicate that the microscopic crystallite and molecular chain orientation rapidly increase at the initial stage of stretching due to macroscopic nanofiber orientation. At higher deformation, the microscopic modes of orientation continuously develop as a result of the nanofiber stretching. The complicated deformation process of non-woven nanofiber mats is discussed in terms of macroscopic nanofiber orientation and the microscopic crystallite and molecular chain orientation.
    Polymer 09/2012; 53(21):4702–4708. · 3.77 Impact Factor
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    ABSTRACT: OBJECTIVE: Phosphoryl oligosaccharides of calcium (POs-Ca) are highly soluble calcium source made from potato starch. The aim of this study was to investigate the optimal concentrations of POs-Ca for the remineralization of subsurface enamel lesions in vitro. DESIGN: Demineralized bovine enamel slabs (n=5) were remineralized in vitro for 24h at 37°C with artificial saliva (AS) containing 0-0.74% POs-Ca to adjust the Ca/P ratio to 0.4-3.0, then sectioned and analysed by transversal microradiography (TMR). The data were analysed by Scheffe's post hoc test. The Ca/P ratio with most remineralization was used to investigate the effect of calcium on enamel remineralization (n=11). The demineralized slabs were treated with AS with calcium-chloride- (CaCl(2)-) or POs-Ca with an identical calcium content, and sectioned for TMR and wide-angle X-ray diffraction (WAXRD) analyses to evaluate the local changes in hydroxyapatite (HAp) crystal content. The data were analysed using the Mann-Whitney U-test. RESULTS: The highest mineral recovery rate resulted from addition of POs-Ca to adjust the Ca/P to 1.67. At this ratio, the mineral recovery rate for AS containing POs-Ca (24.2±7.4%) was significantly higher than that for AS containing CaCl(2) (12.5±11.3%) (mean±SD, p<0.05). The recovery rate of HAp crystallites for AS containing POs-Ca (35.7±10.9%) was also significantly higher than that for AS containing CaCl(2) (23.1±13.5%) (p<0.05). The restored crystallites were oriented in the same directions as in sound enamel. CONCLUSIONS: POs-Ca effectively enhances enamel remineralization with ordered HAp at a Ca/P ratio of 1.67.
    Archives of oral biology 08/2012; · 1.65 Impact Factor
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    ABSTRACT: X-ray diffraction patterns were recorded from isolated single rod outer segments of frog. The outer segments in Ringer's solution were exposed to a 6 µm microbeam (15 keV) at the BL40XU beamline, SPring-8. The diffraction pattern demonstrated a remarkable regularity in the stacking and flatness of the disk membranes. The electron density profile calculated from the intensity of up to tenth-order reflections showed a pair of bilayers that comprise a disk membrane. The structure of the disk membrane and the changes in the profile on swelling generally agreed with previous reports. Radiation damage was significant with an irradiation of 5 × 10(5) Gy which is much lower than the known damaging dose on proteins at the liquid-nitrogen temperature.
    Journal of Synchrotron Radiation 07/2012; 19(Pt 4):574-8. · 2.19 Impact Factor
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    ABSTRACT: Mutations in the gene encoding transglutaminase 1 (TG1) are responsible for various types of autosomal recessive congenital ichthyosis (ARCI), such as lamellar ichthyosis (LI), congenital ichthyosiform erythroderma (CIE) and some minor variants of ARCI. A point mutation of R143C in the β-sandwich domain of TG1 has been often identified in patients with LI or CIE. To elucidate the effect of that point mutation on skin barrier structures and functions, we generated mice with a point mutation of R142C, which corresponds to the R143C mutation in human TG1. A mouse line with the R142C point mutation in TG1 was established using a gene targeting technique and the Cre-loxP system. The skin phenotypes were analyzed in homozygous mutant Tgm1(R142C/R142C) mice. In the skin of Tgm1(R142C/R142C) mice, expression of the mutant transcripts was comparable with wild-type or Tgm1(+/R142C) mice. However, the amount of mutated protein in the skin was markedly decreased in Tgm1(R142C/R142C) mice, and the TG1 activity of Tgm1(R142C/R142C) keratinocytes was almost lost. Tgm1(R142C/R142C) mice exhibited morphological and functional skin barrier defects and neonatal lethality. The stratum corneum of those mice lacked cornified envelopes, and loricrin, the major structural component, failed to assemble at the corneocyte cell periphery. Tgm1(R142C/R142C) mice showed a marked increase in transepidermal water loss and their skin was easily permeable to toluidine blue dye. The intercellular lipid lamellar structures of the stratum corneum were irregular and the 13-nm periodic X-ray diffractions from the stratum corneum lipid molecules were lost in vivo. From these results, we suggest that the R142C mutation of TG1 reduces the enzyme stability which is indispensable for development of the stratum corneum and skin barrier function and for postnatal survival of mice.
    Journal of dermatological science 03/2012; 65(3):196-206. · 3.71 Impact Factor

Publication Stats

113 Citations
122.99 Total Impact Points

Institutions

  • 2007–2014
    • Japan Synchrotron Radiation Research Institute (JASRI)
      Tatsuno, Hyōgo, Japan
  • 2013
    • The University of Tokyo
      • Department of Advanced Materials Science
      Edo, Tōkyō, Japan
  • 2012
    • Kwansei Gakuin University
      • Department of Physics
      Nishinomiya, Hyogo-ken, Japan
  • 2006
    • Fukui University of Technology
      Hukui, Fukui, Japan