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Inoue Y.,Saga University | Noda I.,Japan Medical Materials Corporation | Torikai T.,Saga University | Watari T.,Saga University | And 2 more authors.
Journal of Solid State Chemistry | Year: 2010

Titanium dioxide thin films having various nanostructures could be formed by various treatments on sodium titanate nanotube thin films approximately 5 μm thick fixed on titanium metal plates. Using an aqueous solution with a lower hydrochloric acid concentration (0.01 mol/L) and a higher reaction temperature (90 °C) than those previously employed, we obtained a hydrogen titanate nanotube thin film fixed onto a titanium metal plate by H+ ion-exchange treatment of the sodium titanate nanotube thin film. Calcination of hydrogen titanate nanotube thin films yielded porous thin films consisting of anatase nanotubes, anatase nanowires, and anatase nanoparticles grown directly from the titanium metal plate. H+ ion-exchange treatment of sodium titanate nanotube thin films at 140 °C resulted in porous thin films consisting of rhomboid-shaped anatase nanoparticles. © 2009 Elsevier Inc. All rights reserved. Source

Asakura T.,Tokyo University of Agriculture and Technology | Nishi H.,Tokyo University of Agriculture and Technology | Nagano A.,Tokyo University of Agriculture and Technology | Nagano A.,Japan Medical Materials Corporation | And 4 more authors.
Biomacromolecules | Year: 2011

It is well established that by introducing the cell-adhesive sequence Arg-Gly-Asp (RGD) from fibronectin into Bombyx mori silk fibroin by covalent coupling or bioengineering techniques, excellent biomaterials have been developed with the modified silk fibroin. However, there is no report about the structure and dynamics of the RGD moiety in the silk fibroin. To clarify the origin of such a high cell adhesion character and to design new recombinant silk protein with higher cell adhesion ability, it is necessary to characterize the structure and dynamics of the RGD moiety introduced into silk fibroin. In this study, the structure and dynamics of the RGD moiety in a recombinant silk-like protein, SLPF 10, consisting of the repeated silk fibroin sequence (AGSGAG) 3 and the sequence ASTGRGDSPA including the RGD moiety, were studied using solution NMR. The 1H, 15N, and 13C chemical shifts indicate that the RGD moiety, as well as the silk fibroin sequence, takes a random coil form with high mobility in aqueous solution. Next, a 13C solid-state NMR study was performed on a 13C selectively labeled model peptide, AGSGAG[3- 13C]A 7GSGAGAGSGGT[2- 13C]G 19R[1- 13C]G 21DSPAGGGAGAGSGAG. After formic acid treatment, an increase in the β-sheet fraction for the AGSGAG sequence and peak narrowing of the residues around the RGD moiety were observed in the dry state. The latter indicates a decrease in the chemical shift distribution although the RGD moiety is still in random coil. A decrease in the peak intensities of the RGD moiety in the swollen state after immersing it in distilled water was observed, indicating high mobility of the RGD sequence in the peptide in the swollen state. Thus, the random coil state of the RGD moiety in the recombinant silk-like protein is maintained in aqueous solution and also in both dry and swollen state. This is similar to the case of the RGD moiety in fibronectin. The presence of the linker ASTG at the N-terminus and SPAGG at the C-terminus seems important to maintain the random coil form and the flexible state of the RGD sequence in order to permit access for binding to various integrins. © 2011 American Chemical Society. Source

Kawanabe K.,Kobe City Medical Center General Hospital | Kawanabe K.,Kyoto University | Akiyama H.,Kyoto University | Goto K.,Kyoto University | And 2 more authors.
Journal of Arthroplasty | Year: 2011

Several types of acetabular reinforcement devices are used to prevent the collapse of grafted bone in revision total hip arthroplasty. However, it remains unclear how the stress is reduced by different devices. We used finite element analysis to evaluate 4 types of acetabular reinforcement devices: Kerboull-type device, Burch-Schneider anti-protrusio cage, Mueller ring, and Ganz ring. The control was a socket fixed with bone cement without any reinforcement devices. The stress distribution on the inner surface of each socket was calculated by binarization image processing. For all 4 reinforcement devices, the stress was reduced to less than one-half of that in the control. All the devices were useful for preventing the collapse of bulk bone grafts applied to load-bearing defects. © 2011 Elsevier Inc. Source

Kyomoto M.,University of Tokyo | Kyomoto M.,Japan Medical Materials Corporation | Moro T.,University of Tokyo | Takatori Y.,University of Tokyo | And 3 more authors.
Biomaterials | Year: 2010

Poly(ether-ether-ketone) (PEEK)s are a group of polymeric biomaterials with excellent mechanical properties and chemical stability. In the present study, we demonstrate the fabrication of an antibiofouling and highly hydrophilic high-density nanometer-scaled layer on the surface of PEEK by photo-induced graft polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) without using any photo-initiators, i.e., "self-initiated surface graft polymerization." Our results indicated that the diphenylketone moiety in the polymer backbone acted as a photo-initiator similar to benzophenone. The density and thickness of the poly(MPC) (PMPC)-grafted layer were controlled by the photo-irradiation time and monomer concentration during polymerization, respectively. Since MPC is a highly hydrophilic compound, the water wettability (contact angle <10°) and lubricity (coefficient of dynamic friction <0.01) of the PMPC-grafted PEEK surface were considerably lower than those of the untreated PEEK surface (90° and 0.20, respectively) due to the formation of a PMPC nanometer-scale layer. In addition, the amount (0.05 μg/cm2) of BSA adsorbed on the PMPC-grafted PEEK surface was considerably lower, that is more than 90% reduction, compared to that (0.55 μg/cm2) for untreated PEEK. This photo-induced polymerization process occurs only on the surface of the PEEK substrate; therefore, the desirable mechanical properties of PEEK would be maintained irrespective of the treatment used. © 2009 Elsevier Ltd. All rights reserved. Source

Nagano A.,Japan Medical Materials Corporation | Sato H.,Nissan Chemical Industries Ltd. | Tanioka Y.,Tokyo University of Agriculture and Technology | Nakazawa Y.,Tokyo University of Agriculture and Technology | And 2 more authors.
Soft Matter | Year: 2012

Bombyx mori silk fibroin with the main sequence (Ala-Gly-Ser-Gly-Ala-Gly) n is a promising scaffold for bone regeneration not only on account of its excellent mechanical property as a structural matrix, but also for its slow biodegradability with adequate control of hydroxyapatite (HAP) deposition. Seeking to develop a material that might stimulate bone regeneration, we prepared a recombinant calcium binding-amphipathic silk-like protein [(Glu) 8(Ala-Gly-Ser-Gly-Ala-Gly) 4] 4 by expression in E. coli. We also prepared the homologous peptide (Glu) 8(Ala-Gly-Ser- Gly-Ala-Gly) 4 by solid phase synthesis. The poly-l-glutamic acid was introduced into both protein and peptide because this sequence is involved in HAP-nucleating domains of bone sialoprotein. The recombinant protein was shown to bind relatively large quantities of Ca 2+ ions in solution by a spectrophotometric assay and in the solid state by X-ray photoelectron spectroscopy. Changes in the electronic structure and local conformation of the peptide resulting from Ca 2+ binding were studied using 13C solution NMR, especially 13C chemical shifts. We obtained evidence that Ca 2+ bound to the poly-l-glutamic acid domains but not to the predominantly hydrophobic (Ala-Gly-Ser-Gly-Ala-Gly) 4 domains. A remarkable conformational change induced by adsorption of the synthetic peptide on the HAP surface was also demonstrated using 13C solid state NMR. © 2012 The Royal Society of Chemistry. Source

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