Noboru Ohta

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

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Publications (53)171.54 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The synergistic interactions between the α-amine and the carboxylic acid in an amino acid have recently been studied as bio-based zwitterions. Here, we report a new amphiphilic polymer containing glutamic acid grafted to the end of a dodecyl polymer side chain, which contains the α-amine and the γ-carboxylic acid of the glutamic acid moiety. The polymer self-assembled into a multilayered structure in the thin film, and the glutamic acid moieties in the polymer side chains were exposed to the polymer film/water interface. Annealing the sample enhanced the formation of a well-oriented lamellar structure in the films. Due to the presence of the glutamic acid moieties at the interface, the surface charge was controllable by pH in buffer solutions, resulting in zwitterionic character at neutral pH. It has been widely accepted that zwitterionic surfaces can exhibit non-fouling for proteins. Interestingly enough, the polymer film showed charge-selective protein adsorption since the synergistic interaction between the α-amine and the γ-carboxylic acid was weaker than conventional amino acid-based zwitterionic systems. This is due to the separated state of the functional groups by a three carbon spacer. This journal is
    Polymer Chemistry 10/2015; 6(39). DOI:10.1039/C5PY00783F · 5.52 Impact Factor
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    ABSTRACT: We have investigated the inner structure of shear-induced precursor of shish kebab of isotactic polystyrene (iPS) above the nominal melting temperature Tm using microbeam wide-angle X-ray scattering. We first studied the effects of the shear rate on the inner structure and found that the crystallinity in the precursor increased with the shear rate while the crystallite size was independent of that. This was explained in terms of effects of chain entanglements on shear-induced crystallization. We also studied effects of annealing below the nominal melting temperature Tm and found no changes in the crystallites size before and after the annealing, suggesting that the crystallites did not grow into shishs during the annealing below Tm although the kebabs grew.
    Macromolecules 05/2015; 48(10):150506151126005. DOI:10.1021/acs.macromol.5b00372 · 5.80 Impact Factor

  • Biophysical Journal 01/2015; 108(2):220a. DOI:10.1016/j.bpj.2014.11.1214 · 3.97 Impact Factor
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    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; 55(25). DOI:10.1016/j.polymer.2014.10.026 · 3.56 Impact Factor
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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.
    Scientific Reports 09/2014; 4. DOI:10.1038/srep06384 · 5.58 Impact Factor
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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; 118(35). DOI:10.1021/jp505556r · 3.30 Impact Factor
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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; 10(41). DOI:10.1039/C4SM01355G · 4.03 Impact Factor
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    Noboru Ohta · Hiroshi Sekiguchi · Yuji C. Sasaki · Naoto Yagi ·
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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(2-2). DOI:10.1107/S1600576714002210 · 3.72 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. DOI:10.1021/ma402041r · 5.80 Impact Factor

  • Hyomen Kagaku 01/2014; 35(1):34-39. DOI:10.1380/jsssj.35.34
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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; 29(45). DOI:10.1021/la403377a · 4.46 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. DOI:10.1063/1.4819305 · 1.61 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.
    06/2013; 4(13):3735-3743. DOI:10.1039/C3PY00172E
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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. DOI:10.1021/ma4001868 · 5.80 Impact Factor
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    ABSTRACT: We applied the microbeam two-dimensional small-angle X-ray scattering (2d-µSAXS) technique in order to characterize orientation of polystyrene (PS) microdomains as a function of the distance from the free surface of a sample sheet down to the surface facing to the substrate, for depth profiling for spontaneous perpendicular orientation of PS cylinders in the matrix of polyethylenebutylene (PEB) in a PS-b-PEB-b-PS triblock copolymer thick sheet as thick as ∼0.5 mm. It has been revealed that near the free surface the cylinders were randomly oriented down to ∼70 µm in depth. Although this might indicate that the surface effect, which preferentially dictates cylinders to be oriented parallel to the surface, can propagate for such a long distance, 70 µm is unusually huge as compared to the general knowledge of the surface effect propagating at most for 1 µm. Experimentally examining further, we finally conclude that the 2d-µSAXS depth profiling overestimates the surface effect. This unfavorable conclusion may be ascribed to surface roughness of the sample sheet subjected to the measurement, and in order to obtain a good result a big effort is required to prepare the surface as flat as possible.
    Macromolecular Symposia 05/2013; 327(1):121-127. DOI:10.1002/masy.201350515
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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. DOI:10.1021/mz400136d · 5.76 Impact Factor
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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. DOI:10.1021/ma400061a · 5.80 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-. DOI:10.7567/JJAP.52.035002 · 1.13 Impact Factor

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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; 135(7). DOI:10.1021/ja308965j · 12.11 Impact Factor

Publication Stats

339 Citations
171.54 Total Impact Points


  • 2006-2015
    • Japan Synchrotron Radiation Research Institute (JASRI)
      Tatsuno, Hyōgo, Japan
  • 2013
    • Kyushu University
      Hukuoka, Fukuoka, Japan
  • 2012
    • Kobe University
      • Department of Physics
      Kōbe, Hyōgo, Japan