Faculty Profiles - HAYAKAWA Satoshi

Papers - HAYAKAWA Satoshi

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Preparation of alginic acid layers on stainless-steel substrates for biomedical applications Reviewed

T Yoshioka, K Tsuru, S Hayakawa, A Osaka

BIOMATERIALS 24 ( 17 ) 2889 - 2894 2003.8

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI LTD

This study is concerned with the blood compatibility of alginic acid layers immobilized on gamma-aminopropyltriethoxysilane (gamma-APS)-grafted stainless-steel (SUS316L). The surfaces were characterized with contact angle measurement and X-ray photoelectron spectroscopy (XPS). The blood compatibility was evaluated in terms of platelet adhesion and blood clotting time. Ail in vitro platelet adhesion assay indicated that only a small number of platelets adhered to substrate surfaces modified with gamma-APS and subsequently with alginic acid. Moreover, alginic-acid-immobilized SUS316L substrates had little effect on the blood clotting time. This indicated that alginic-acid-immobilized SUS316L substrates do not adsorb some blood-clotting proteins or factors, or stimulate them. (C) 2003 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0142-9612(03)00127-3

Bioceramic coatings of titanium surfaces Reviewed

Jinming Wu, Satoshi Hayakawa, Kanji Tsuru, Akiyoshi Osaka

Kuei Suan Jen Hsueh Pao/ Journal of the Chinese Ceramic Society 31 692 - 697 2003.7

The bioactive fixation between bone substitutes and their surrounding tissues is mostly studied in the nearest decade. The key of bioactive fixation is the high bioactivity of the biomaterials. To coat the titanium surface with a layer of bioceramics through physical deposition, sol-gel, electrochemical deposition, biomimetic process, etc. can promote the bioactivity of titanium effectively. Another approach to obtain a bioactive titanium surface is the chemical modification of titanium with sodium hydroxygen or hydrogen peroxide solution to induce titanium dioxide films on the surface. The titanium dioxide films derived by the surface modification should be abundant in Ti-OH functional groups, and also, in crystalline structure, which may effectively induce the epitaxial growth of hydroxylapatite nuclei. This paper provides a brief review of various techniques and their corresponding mechanisms for obtaining a titanium surface with bioactivity.

Bioactivity of viscoelastic Ormosil-type organic-inorganic hybrids containing colloidal silica particles Reviewed

Y Aburatani, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 111 ( 5 ) 318 - 322 2003.5

Language：English Publishing type：Research paper (scientific journal) Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

Synthesized were organically modified silicate (ORMOSILs) hybrids containing colloidal silica as an ingredient, starting from poly (dimethylsiloxane) (PDMS), tetraethoxysilane (TEOS) and calcium nitrate through sol-gel processing. The effects of pre-hydrolysis of TEOS on mechanical strength and viscoelasticity were examined. A sample of composition PDMS/TEOS = 0.60 (molar ratio) with pre-hydrolysis of TEOS showed about 65% maximum failure strain. Thus obtained hybrid exhibited a peak at around -75degreesC in the storage modulus-temperature curve of the hybrid, due to transverse movements of the PDMS chains. This hybrid, heated at 200degreesC deposited apatite within 1 d in the simulated body fluid of the Kokubo recipe.

Mechanical property and microstructure of bioactive organic-inorganic hybrids containing colloidal silica particles Reviewed

Y Aburatani, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 111 ( 4 ) 247 - 251 2003.4

Language：English Publishing type：Research paper (scientific journal) Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

Synthesized through sol-gel processing were Ormosil type hybrid gels containing varied mass fractions of colloidal silica, poly (dimethylsiloxane) (PDMS), tetraethoxysilane (TEOS) and calcium nitrate. Viscoelasticity, mechanical strength and Si-29 MAS NMR spectra were measured, and in vitro apatite deposition in a simulated body fluid (SBF) of the Kokubo recipe was examined. The relative height of a T-g peak at about -100degreesC in tan delta versus temperature curves grew with the colloidal silica content. This peak growth was accounted for the relative increase in PDMS-colloidal silica interactions. As the increase in the compressive strength followed the increase in colloidal silica content, the number of PDMS-silica bonds and hydrogen bond of colloidal silica increased due to the NMR spectra and tan delta curve. Thus, mechanical strength was dependent on PDMS-silica bonds and the hydrogen bond of colloidal silica. On the other hand, as the relative PDMS content increased, the number of PDMS-silica bonds was little influenced while PDMS chain structure increased. The gel (with a molar ratio TEOS: PDMS:H2O:HCl: Ca(NO3)(2).4H(2)O = 1:0.48:5.0:0.9:0.10) containing 14 mass% colloidal silica (CS14P0.48Ca0.10) exhibited the highest maximum failure strain (about 70%) among all samples. Thus, the relative content of PDMS chain structure depending on PDMS content influenced the maximum failure strain. CS14P0.48Ca0.25 could not deposit apatite within 7 d after soaking in SBF, while PDMS/TEOS = 0.24 (molar ratio) could deposit apatite within 3 d. The increase in PDMS content restrained the dissolution of Ca ions.

Structure and biomineralization of calcium silicate glasses containing fluoride ions Reviewed

Eiji Fuji, Koji Kawabata, Hideyuki Yoshimatsu, Satoshi Hayakawa, Kanji Tsuru, Akiyoshi Osaka

Journal of the Ceramic Society of Japan 111 ( 1298 ) 762 - 766 2003.1

Language：English Publisher：The Ceramic Society of Japan

The in vitro bioactivity, in terms of apatite-forming ability, of calcium silicate glasses containing 10 mol% fluoride ions in the NaF-CaO-SiO2system was examined by soaking in Kokubo's simulated body fluid (SBF) at 36.5°C for 7 d. The surface structure of the glasses was examined by thin-film X-ray diffraction (TF-XRD) and Fourier transform infrared reflection spectroscopy (FT-IR) in order to confirm the apatite deposition. The structure of the calcium silicate glasses was examined by29Si magic angle spinning-nuclear resonance spectroscopy (MAS-NMR) and X-ray photoelectron spectroscopy (XPS). Three calcium silicate glasses containing 10 mol% fluoride ions had different apatite-forming abilities. In the case of CaO/SiO2=1, the apatite-forming ability of 10NaF·45CaO·45SiO2was lower than that of 50CaO·50SiO2. This indicated that the addition of fluoride ions suppressed the apatite-forming ability, irrespective of the structural similarity of the silicate network based on the ratio of CaO/SiO2between the glasses.

DOI： 10.2109/jcersj.111.762

Mechanical property and microstructure of bioactive organic-inorganic hybrids containing colloidal silica particles Reviewed

Yasushi Aburatani, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

Journal of the Ceramic Society of Japan 111 ( 1292 ) 247 - 251 2003

Language：English Publishing type：Research paper (scientific journal) Publisher：Ceramic Society of Japan

Synthesized through sol-gel processing were Ormosil type hybrid gels containing varied mass fractions of colloidal silica, poly (dimethylsiloxane) (PDMS), tetraethoxysilane (TEOS) and calcium nitrate. Viscoelasticity, mechanical strength and 29Si MAS NMR spectra were measured, and in vitro apatite deposition in a simulated body fluid (SBF) of the Kokubo recipe was examined. The relative height of a Tg peak at about - 100°C in tan δ versus temperature curves grew with the colloidal silica content. This peak growth was accounted for the relative increase in PDMS-colloidal silica interactions. As the increase in the compressive strength followed the increase in colloidal silica content, the number of PDMS-silica bonds and hydrogen bond of colloidal silica increased due to the NMR spectra and tan δ curve. Thus, mechanical strength was dependent on PDMS-silica bonds and the hydrogen bond of colloidal silica. On the other hand, as the relative PDMS content increased, the number of PDMS-silica bonds was little influenced while PDMS chain structure increased. The gel (with a molar ratio TEOS:PDMS:H2O:HCl:Ca (NO3)2·4H2O = 1:0.48:5.0:0.9:0.10) containing 14 mass% colloidal silica (CS14P0.48Ca0.10) exhibited the highest maximum failure strain (about 70%) among all samples. Thus, the relative content of PDMS chain structure depending on PDMS content influenced the maximum failure strain. CS14P0.48Ca0.25 could not deposit apatite within 7 d after soaking in SBF, while PDMS/TEOS = 0.24 (molar ratio) could deposit apatite within 3 d. The increase in PDMS content restrained the dissolution of Ca ions.

DOI： 10.2109/jcersj.111.247

Early Apatite Deposition onTitanium Treated by Hydrogen Peroxide Reviewed

Jin-Ming Wu, Satoshi Hayakawa, Kanji Tsuru, Akiyoshi Osaka

J. Aust, Ceram, Soc. 2003

Bioactivity of viscoelastic ormosil-type organic-inorganic hybrids containing colloidal silica particles Reviewed

Yasushi Aburatani, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

Journal of the Ceramic Society of Japan 111 ( 1293 ) 318 - 322 2003

Language：English Publishing type：Research paper (scientific journal) Publisher：Ceramic Society of Japan

Synthesized were organically modified silicate (ORMOSILs) hybrids containing colloidal silica as an ingredient, starting from poly (dimethylsiloxane) (PDMS), tetraethoxysilane (TEOS) and calcium nitrate through sol-gel processing. The effects of pre-hydrolysis of TEOS on mechanical strength and viscoelasticity were examined. A sample of composition PDMS/TEOS = 0.60 (molar ratio) with pre-hydrolysis of TEOS showed about 65% maximum failure strain. Thus obtained hybrid exhibited a peak at around -75°C in the storage modulus-temperature curve of the hybrid, due to transverse movements of the PDMS chains. This hybrid, heated at 200°C deposited apatite within 1 d in the simulated body fluid of the Kokubo recipe.

DOI： 10.2109/jcersj.111.318

Sol-Gel Preparation of Blood-Compatible Titania as an Adsorbent of Bilirubin Reviewed

Takuji Asano, Shinji Takemoto, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka, Seisuke Takashima

Journal of the Ceramic Society of Japan 111 ( 1297 ) 645 - 650 2003

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Ceramic Society of Japan

This study concerns with the adsorption of pathogenic substances on highly blood-compatible titania and the adsorption mechanism. Titania was prepared through a sol-gel procedure by hydrolyzing tetraethylor-thotitanate and calcining up to 705°C for 3 h. Pore size distribution and surface charge density were measured as a function of calcining temperature. Adsorption of bilirubin, as a typical pathogenic substance, as well as albumin on the titania powder was studied. Bilirubin was adsorbed either in 4 to 8-nm pores or on the surface with a higher positive charge. Thus, either entrapping bilirubin in the pores or electrostatic interaction between bilirubin and titania surface was effective for the adsorption of bilirubin. The titania powder adsorbed a greater amount of bilirubin than the anion-exchange resin used in clinics, hence they have potential for blood purification therapy.

DOI： 10.2109/jcersj.111.645

In vitro bioactivity of anatase film obtained by direct deposition from aqueous titanium tetrafluoride solutions Reviewed

JM Wu, S Hayakawa, K Tsuru, A Osaka

THIN SOLID FILMS 414 ( 2 ) 275 - 280 2002.7

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

Well-crystallized anatase films were deposited on commercially available pure titanium substrates from an acid titanium tetrafluoride aqueous solution kept at 60 degreesC for 24 h. The anatase films consisted of dual layers that were different in topography: a dense inner layer strongly adhered to the Ti substrate and a porous outer layer. In vitro bioactivity of such films was evaluated by soaking them in a simulated body fluid (SBF) of the Kokubo solution to observe their ability to induce apatite deposition. The anatase films with a subsequent thermal treatment at a temperature range of 300-700 degreesC induced apatite deposition within 5 days. Apatite particles were also found to deposit within 7 days on the anatase films being heated at 800 degreesC, which involved much rutile due to direct air oxidation of the titanium substrate. When the heating temperature is lower than 200 degreesC, no apatite deposited on the films even after 10 days of soaking in the SBF solution. The improved in vitro bioactivity of the films subsequently heated over 300 degreesC was attributed to the elimination of fluorine. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0040-6090(02)00498-4

Soft solution approach to prepare crystalline titania films Reviewed

JM Wu, S Hayakawa, K Tsuru, A Osaka

SCRIPTA MATERIALIA 46 ( 10 ) 705 - 709 2002.5

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Titania films with crystal structures of anatase or a mixture of anatase and rutile were prepared through a soft solution approach. The crystalline titania film resulted from crystallization of the previously deposited amorphous gel in an acidic solution. A low pH value of the solution favored the formation of rutile. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S1359-6462(02)00056-8

Mechanical properties and microstructure of bioactive ORMOSILs containing silica particles Reviewed

Y Aburatani, K Tsuru, S Hayakawa, A Osaka

MATERIALS SCIENCE & ENGINEERING C-BIOMIMETIC AND SUPRAMOLECULAR SYSTEMS 20 ( 1-2 ) 195 - 198 2002.5

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We synthesized organically modified silicate (ORMOSILs) gels with colloidal silica (CS) (AEROSIL(R)) starting from polydimethylsiloxane (PDMS), tetraethoxysilane (TEOS) and calcium nitrate (Ca(NO3)(2).4H(2)O) through sol-gel processing. Dynamic mechanical analysis indicated that relative height of the tandelta peak at about - 100 degreesC increased with an increase in the relative content of the inorganic components. This peak growth was accounted for by the relative increase in PDMS-colloidal silica particle interactions. The colloidal silica could control the mechanical behavior of the hybrids. The gel of a specific composition could deposit apatite within 3 days of soaking in the simulated body fluid (SBF), since it included many calcium ions on the surface. (C) 2002 Elsevier Science B.V All rights reserved.

DOI： 10.1016/S0928-4931(02)00032-2

Bioactive titania gel layers formed by chemical treatment of Ti substrate with a H2O2/HCl solution Reviewed

XX Wang, S Hayakawa, K Tsuru, A Osaka

BIOMATERIALS 23 ( 5 ) 1353 - 1357 2002.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI LTD

An amorphous titania gel layer was formed on the titanium surface after the titanium specimen was treated with a H2O2/0.1 M HCl solution tit 80degreesC. The thickness of the get layer increased almost linearly With the period of the treatment. A Subsequent heat treatment above 300degreesC transformed gradually the amorphous gel to the anatase crystal structure and the rutile started to appear after heat treatment at 600degreesC. Meanwhile, the densification of the gel occurred significantly after heat treatment above 700degreesC. e Similar to the sol-gel derived titania gel coatings, titania gel layers obtained in the present study exhibited in vitro apatite deposition C ability after the gel layers exceeded a minimum thickness (0.2 mum) and was subsequently heated in a proper temperature range (400-600degreesC). (C) 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0142-9612(01)00254-X

Nanocrystalline titania made from interactions of Ti with hydrogen peroxide solutions containing tantalum chloride Reviewed

JM Wu, S Hayakawa, K Tsuru, A Osaka

CRYSTAL GROWTH & DESIGN 2 ( 2 ) 147 - 149 2002.3

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Crystalline titania film and powders with crystallite size in the range of nanometers are of great interest in the fields of optical devices, gas sensors, catalysts, and biomaterials. This paper reports a soft solution approach to prepare crystalline titania. After Ti was soaked in hydrogen peroxide solutions containing 3.0 mM tantalum chloride at 80 degreesC for 3 days, crystalline titania films consisting of anatase and rutile were deposited on Ti substrates. While Ti was soaked in tantalum-free hydrogen peroxide solution followed by aging in hydrogen peroxide solution containing tantalum ions, titania films with well-crystallized anatase were obtained. The crystalline titania resulted from crystallization of the previously deposited amorphous gel. Addition of tantalum ions in hydrogen peroxide solutions helps to obtain the crystalline titania and favors especially the formation of rutile phase.

DOI： 10.1021/cg015535y

Crystallization of anatase from amorphous titania in hot water and in vitro biomineralization Reviewed

JM Wu, S Hayakawa, K Tsuru, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 110 ( 2 ) 78 - 80 2002.2

Language：English Publishing type：Research paper (scientific journal) Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

Anatase of good crystallinity has been developed on titanium substrates by soaking in a 30 mass% hydrogen peroxide solution at 80degreesC for 8 h, soaking in distilled water at ambient temperature for 12 h, and subsequently aging in distilled water at 80degreesC for 3d. The anatase layers exhibit good bioactivity as inducing apatite deposition in Kokubo's simulated body fluid within 2d.

DOI： 10.2109/jcersj.110.78

Porous titania films prepared from interactions of titanium with hydrogen peroxide solution Reviewed

JM Wu, S Hayakawa, K Tsuru, A Osaka

SCRIPTA MATERIALIA 46 ( 1 ) 101 - 106 2002.1

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Anatase films with sub-micron porous structure were deposited homogeneously on Ti substrates by simply soaking in 15 wt.% hydrogen peroxide solution at 80 degreesC for 1 h followed by heating at 300 degreesC for 1 h in air. Deposition of the porous titania film was not sensitive to substrate morphology, whilst affected readily by the reaction rate. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S1359-6462(01)01207-6

Novel approach to fabricate porous gelatin-siloxane hybrids for bone tissue engineering Reviewed

Lei Ren, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

Biomaterials 23 ( 24 ) 4765 - 4773 2002

Language：English Publishing type：Research paper (scientific journal)

Porous and bioactive gelatin-siloxane hybrids were successfully synthesized by using a combined sol-gel processing, post-gelation soaking, and freeze-drying process to provide a novel kind of materials in the developments and optimization of bone tissue engineering. The pore sizes of the hybrids can be well controlled by varying the freezing temperature. The scaffolds were soaked in a simulated body fluid (SBF) up to 14 days to evaluate the in vitro bioactivity. The Ca2+-containing scaffolds showed in vitro bioactivity as they biomimetically deposited apatite, but the Ca2+-free scaffolds failed. Cytotoxicity and cytocompatibility of those scaffolds and their extracts were monitored by the MC3T3-E1 cell responses, including the cell proliferation and the alkaline phosphatase activity. It was demonstrated that appropriate incorporation of Ca2+ ions stimulated osteoblast proliferation and differentiation in vitro. © 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0142-9612(02)00226-0

Incorporation of Ca2+ ions in gelatin-siloxane hybrids through a sol-gel process Reviewed

L Ren, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 109 ( 5 ) 406 - 411 2001.5

Language：English Publishing type：Research paper (scientific journal) Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

Several gelatin-siloxane hybrids incorporating Ca2+ ions were synthesized through a sol-gel process starting with gelatin, 3-(glycidoxypropyl) trimethoxysilane (GPSM), and Ca(NO3)(2). Amino acid analysis, Si-29 NMR spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, and dynamic mechanical thermal analysis were used to assess the hybrid structure. It has been indicated that the grafting degree of epoxy groups of GPSM to gelatin and the extent of polymerization of methoxysilane end groups of GPSM strongly depended on the fraction of GPSM (f(G)) in the hybrids, but not on incorporation of Ca2+ ions. Hence, the hybrids with the same f(G) value, independent of incorporation of Ca2+ ions, had a similar cross-link density. However, the glass transition temperature (T-g) and storage modulus (E') around T-g decreased with incorporation of Ca2+ ions. Through the deconvolution of amide I bands of FT-IR spectra, flexibility may be interpreted by that the percentage of gelatin having a random structure increased with incorporation of Ca2+ ions. The Ca2+-containing hybrids can spontaneously deposit apatite when they were soaked in a simulated body fluid of the Kokubo recipe, showing their bioactivity.

DOI： 10.2109/jcersj.109.1269_406

Viscoelastic properties and bioactivity of sol-gel derived gelatin-silicate composites: Effects of the incorporated Ca2+ ions Reviewed

L Ren, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY 17 ( 3 ) 367 - 370 2001.5

Language：English Publishing type：Research paper (scientific journal) Publisher：JOURNAL MATER SCI TECHNOL

Several gelatin-silicate composites, with or without incorporation of Ca2+ ions, were synthesized through set-gel processing starting from gelatin and 3- (glycidoxypropyl) trimethoxysilane. The structure around the Si atoms was similar for all the samples. The measurement of viscoelastic properties indicated that the glass transition temperature and activation energy decreased with the incorporation of Ca2+ ions. The Ca2+ ion-containing composites were bioactive as they spontaneously deposited apatite when soaked in a simulated body fluid of the Kokubo recipe.

Kinetics of apatite deposition of silica gel dependent on the inorganic ion composition of simulated body fluids Reviewed

K Tsuru, M Kubo, S Hayakawa, C Ohtsuki, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 109 ( 5 ) 412 - 418 2001.5

Language：English Publishing type：Research paper (scientific journal) Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

Nucleation and crystal growth mechanism of apatite formation on porous silica gel derived by a sol-gel procedure was investigated by the use of several simulated body fluids (SBF's) that had different concentrations of Ca(II), P(V), and OH- but had the same degree of supersaturation for hydroxyapatite. Induction time of apatite crystallization in SBF's was evaluated by thin film X-ray diffractometry. The effect of each ion on the induction time increased in the order: Ca(II)-rich SBF <P(V)-rich SBF <much less than>OH--rich SBF, while that for the rate of initial crystal growth of apatite increased in the order: P (V)-rich SBF < Ca (II)-rich SBF < OH--rich SBF. It suggested that amorphous calcium phosphate (ACP) deposited as the precursor of apatite and ACP transformed into apatite nuclei by the incorporation of OH-. Moreover, the transformation was accelerated by large amount of ACP and was assisted by the rearrangement of silicate units in the gel surface. Ca(II) was richer in ACP deposited in Ca(II)-rich SBF and OH--rich SBF than that deposited in P (V) -rich SBF. Ca(II)-rich ACP was favorable for crystal growth.

DOI： 10.2109/jcersj.109.1269_412

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