Faculty Profiles - HAYAKAWA Satoshi

Papers - HAYAKAWA Satoshi

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Novel process of submicron-scale ceramic rod array formation on metallic substrate Reviewed

Kazuya Okamoto, Satoshi Hayakawa, Kanji Tsuru, Akiyoshi Osaka

Ceramic Transactions 195 133 - 138 2006.7

Authorship：Corresponding author

Nano-scale rods of titania and tungsten oxide were fabricated on metallic titanium and tungsten substrates by heat-treatment in vucuo. The surface structure and morphology were characterized by Thin-film X-ray diffraction analysis (TF-XRD) und scanning electron microscopy. The TF-XRD analysis indicated that the thermal treatment in vacuo (6.7 × 10-2 Pa) gave TiO2 (rutile; PDF#21-1276) and WO3 (PDF#20-1324) nano-scale rod arrays. The mechanism of the nano-scale rod array formation was explained by the structure matching due to topotaxy and the crystal growth habit.

Apatite formation on rutile and anatase layers derived by hydrolysis of titanylsulfate in a simulated body fluid Reviewed

JM Zhao, JF Liu, JM Wu, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 114 ( 1327 ) 253 - 258 2006.3

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

Titania layers were deposited on titanium substrates in titanylsulfate solutions under varied concentration (0.01 and 0.03M), pH (0.67-1.27) and temperature (60 and 80 degrees C). They were rinsed and subsequently aged in water at 80 degrees C for 3d. The layers consisted of only rutile or rutile with trace anatase, depending on the conditions. The X-ray diffraction intensity indicates that the rutile particles grew preferably in (101) plane, regardless of being aged or not. When aged, the anatase diffraction intensity increased, and anatase newly grew in the layer consisting only of rutile. When soaked in a simulated body fluid (SBF) of the Kokubo recipe, the rinsed layer with only rutile was weakly active to deposit apatite within 5 d, while the other two exhibited no deposition. The aging improved activity. Although anatase is reported in the literature to be more active than rutile, the present study indicates that the rutile layer is more active. Thus, it is concluded that topotaxy or epitaxy would not work well but other issues like the presence of Ti-OH affect apatite deposition.

Selective protein adsorption property and characterization of nano-crystalline zinc-containing hydroxyapatite Reviewed

E Fujii, M Ohkubo, K Tsuru, S Hayakawa, A Osaka, K Kawabata, C Bonhomme, F Babonneau

ACTA BIOMATERIALIA 2 ( 1 ) 69 - 74 2006.1

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

Nano-crystalline Zn-containing hydroxyapatite (ZnHAp) was prepared by the wet-chemical method and the selective adsorption of essential proteins was examined, taking bovine serum albumin (BSA) and pathogenic protein such as β2-microglobulin (β2-MG) as model proteins. Transmission electron microscopy observation and X-ray diffraction analysis indicated that the increase of Zn content led to smaller crystallites and their specific surface area of ZnHAps increased with increasing Zn content, accordingly. Furthermore, the amounts of BSA adsorption on ZnHAp particles decreased with increasing Zn content in spite of the increase in the specific surface area. It is thus concluded that nano-crystalline ZnHAps had a highly selective adsorption property with regard to β2-MG. © 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.actbio.2005.09.002

Cytocompatibility of silicone elastomer grafted with gamma-methacryloxypropyltrimethoxysilane Reviewed

Y Shirosaki, K Tsuru, S Hayakawa, A Osaka, S Takashima

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 114 ( 1325 ) 72 - 76 2006.1

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

gamma-Methacryloxypropyltrimethoxysilane (gamma-MPS) was grafted on a silicone elastomer by emulsion polymerization in order to improve cytocompatibility. The wettability of the grafted surface was evaluated with a contact angle toward distilled water. By grafting within 30 min at 60 degrees C, the contact angle was reduced from 110 degrees to about 70 degrees while it remained almost constant for longer grafting. A larger number of osteoblastic cells (MCM-E1) and fibroblast cells (L929) proliferated on the surface modified with gamma-MPS compared with the original silicone surface. After culturing for 7 d, the cells completely covered the grafted surface and even formed a cell layer.

In vivo performance of biodegradable calcium phosphate glass ceramics using the rabbit model: Histological and SEM observation Reviewed

AG Dias, MA Lopes, JD Santos, A Afonso, K Tsuru, A Osaka, S Hayakawa, S Takashima, Y Kurabayashi

JOURNAL OF BIOMATERIALS APPLICATIONS 20 ( 3 ) 253 - 266 2006.1

Language：English Publishing type：Research paper (scientific journal) Publisher：SAGE PUBLICATIONS LTD

Two MK5 (45CaO-45P(2)O(5)-5MgO-5K(2)O, in mol%) and MT13 (45CaO-37P(2)O(5)-5MgO-13TiO(2), in mol%) glasses are prepared in the meta- and pyrophosphate regions and crystallized to obtain MK5B and MT13B, respectively. MK5B was obtained by controlled crystallization, and MT13B by powder sintering. As a result of these heat treatment processes, the crystalline phases precipitated in the glassy matrix are KCa(PO3)(3), beta-Ca(PO3)(2), beta-Ca2P2O7 and Ca4P6O19 phases for MK5B and CaTi4(PO4)(6), TiP2O7, alpha- and beta-Ca2P2O7 phases for MT13B. To assess the in vivo biological behavior of these glass ceramics, a mixed granulometry in the range 250-355 mu m and 355-425 mu m with a ratio of 1/1 was implanted for 2, 4, and 12 weeks in the tibiae of Japanese white rabbits. The results showed that the in vivo behavior was strongly affected by their solubility. All implanted materials, MK5B and MT13B, and beta-tricalcium phosphate (beta-TCP) as control material, showed signs of degradation in vivo. However, the levels of degradation were quite different throughout the implantation periods. The highest degradation was observed for MK5B glass ceramic and the lowest for MT13B with beta-TCP in-between. All implanted materials allow for new bone formation in the bone defect area. At the longest implantation period (12 weeks), the MT13B and beta-TCP materials were almost completely surrounded by new bone tissue, whereas MK5B showed some unfilled spaces. This behavior is discussed in terms of the high degradation observed in previous studies.

DOI： 10.1177/0885328206052466

Apatite formation on rutile and anatase layers derived by hydrolysis of titanylsulfate in a simulated body fluid Reviewed

Jia-Ming Zhao, Jin-Fang Liu, W. U. Jin-Ming, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

Journal of the Ceramic Society of Japan 114 ( 1327 ) 253 - 258 2006

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

Titania layers were deposited on titanium substrates in titanylsulfate solutions under varied concentration (0.01 and 0.03M), pH (0.67-1.27) and temperature (60 and 80°C). They were rinsed and subsequently aged in water at 80°C for 3d. The layers consisted of only rutile or rutile with trace anatase, depending on the conditions. The X-ray diffraction intensity indicates that the rutile particles grew preferably in (101) plane, regardless of being aged or not. When aged, the anatase diffraction intensity increased, and anatase newly grew in the layer consisting only of rutile. When soaked in a simulated body fluid (SBF) of the Kokubo recipe, the rinsed layer with only rutile was weakly active to deposit apatite within 5 d, while the other two exhibited no deposition. The aging improved activity. Although anatase is reported in the literature to be more active than rutile, the present study indicates that the rutile layer is more active. Thus, it is concluded that topotaxy or epitaxy would not work well but other issues like the presence of Ti-OH affect apatite deposition.

DOI： 10.2109/jcersj.114.253

Chemical interaction of phosphoric acid ester with hydroxyapatite Reviewed

D. Fukegawa, S. Hayakawa, Y. Yoshida, K. Suzuki, A. Osaka, B. Van Meerbeek

Journal of Dental Research 85 ( 10 ) 941 - 944 2006

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：SAGE Publications Inc.

Among functional monomers used in contemporary dental adhesives, 10-methacryloyloxydecyl dihydrogen phosphate (MDP) has been found to interact chemically with hydroxyapatite (HAp) most intensively and stably. This effect was thought to be the basis of the superior bonding effectiveness of MDP-based self-etch adhesives to enamel/dentin. To elucidate fully the chemical interaction and reactivity of MDP with HAp, we used 31P CP-MAS NMR spectroscopy and powder x-ray diffraction. In an aqueous ethanol solution, Ca ions were leached from HAp to form, at short term, a MDP-calcium salt (CaMHP2) layered structure on the HAp surface. When MDP was allowed to interact for longer time (&lt
24 hrs), CaHPO4·2H 2O precipitated on top of this MDP-calcium salt layered structure. In conclusion, the intense chemical interaction of MDP with HAp must be ascribed to superficial dissolution of HAp induced by the MDP adsorption and subsequent deposition of MDP-calcium salt with a solubility lower than that of CaHPO 4·2H2O.

DOI： 10.1177/154405910608501014

Synthesis and structural characterization of silica-hybridized hydroxyapatite with gas adsorption capability Reviewed

Eiji Fujii, Koji Kawabata, Kanae Ando, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

Journal of the Ceramic Society of Japan 114 ( 1333 ) 769 - 773 2006

Language：English Publisher：Ceramic Society of Japan

Silica-hybridized hydroxyapatite powder was prepared from a calcium hydroxide and phosphoric acid together with a tetra-n-butyl orthosilicate as the silica source in order to apply it as a gas adsorbent. According to the X-ray diffraction patterns, all peaks were assigned to the hydroxyapatite. No secondary phases, such as calcium hydroxide and silicon oxides, were observed. Moreover, the transmission electron microscope observations indicated that the crystallite size hardly changed by increasing the silicon oxide content. However, the adsorption areas of nitrogen, water and benzene were remarkably dependent on the silicon oxide content. In this paper, in order to explain the change in the adsorption areas, the lattice structure of the silica-hybridized hydroxyapatite is discussed based on the results obtained by the 29Si and 31P magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR).

DOI： 10.2109/jcersj.114.769

Cytocompatibility of silicone elastomer grafted with γ-Methacryloxypropyltrimethoxysilane Reviewed

Yuki Shirosaki, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka, Seisuke Takashima

Journal of the Ceramic Society of Japan 114 ( 1325 ) 72 - 76 2006

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

γ-Methacryloxypropyltrimethoxysilane (γ-MPS) was grafted on a silicone elastomer by emulsion polymerization in order to improve cytocompatibility. The wettability of the grafted surface was evaluated with a contact angle toward distilled water. By grafting within 30 min at 60°C, the contact angle was reduced from 110° to about 70° while it remained almost constant for longer grafting. A larger number of osteoblastic cells (MC3T3-E1) and fibroblast cells (1929) proliferated on the surface modified with γ-MPS compared with the original silicone surface. After culturing for 7 d, the cells completely covered the grafted surface and even formed a cell layer.

DOI： 10.2109/jcersj.114.72

Synthesis and structural characterization of nanoapatite ceramics powders for biomedical applications

Kanae Ando, Mizuki Ohkubo, Satoshi Hayakawa, Kanji Tsuru, Akiyoshi Osaka, Eiji Fujii, Koji Kawabata, Christian Bonhomme, Florence Babonneau

Ceramic Transactions 195 125 - 131 2006

Language：English Publishing type：Research paper (international conference proceedings)

Zn/HAp particles were prepared by soaking hydroxyapatite (HAp), derived through a wet chemical method, into aqueous solutions containing various amounts of zinc nitrate. Obtained samples were characterized by inductively coupled plasma emission spectroscopy, X-ray diffraction (XRD), Brunauer-Emmett-Teller surface area analysis (SA), and transmission electron microscopy. Their zeta potential was also measured. The analyzed Zn content was almost proportional to the content in the aqueous solutions. The Zn 2+ ions were partially replaced the Ca 2+ ions in the apatite, and hence, little change was observed in crystallinity, particle size and SA. Adsorption of bovine serum albumin (BSA) and ß 2-microglobulin (ß 2-MG) in the solutions containing both BSA and ß 2-MG was examined. As the Zn 2+ ion content in the apatites increased, the adsorbed amount of BSA was almost constant, whereas that of ß 2-MG increased. Thus, the Zn incorporation increased the selectivity, and it is suggested that the Zn-substituted site should be the active ones for ß 2-MG adsorption.

In vitro apatite formation on organic polymers modified with a silane coupling reagent Reviewed

Y Shirosaki, M Kubo, S Takashima, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF THE ROYAL SOCIETY INTERFACE 2 ( 4 ) 335 - 340 2005.9

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOCIETY

gamma-Methacryloxypropyltrimethoxysilane (gamma-MPS) was grafted to high-density polyethylene, polyamide and silicone rubber substrates by the emulsion polymerization procedure in order to provide these organic polymers with in vitro apatite-forming ability. The contact angles towards distilled water of the gamma-MPS-grafted specimens were lower than those of the original organic polymer specimens, indicating that the grafted substrates were more hydrophilic. The in vitro apatite formation in a simulated body fluid (Kokubo solution) was confirmed for several of the gamma-MPS-grafted specimens.

DOI： 10.1098/rsif.2005.0048

ヒドロキシアパタイトとリン酸エステル系機能性モノマーの化学的相互作用

泓川大輔, 吉田靖弘, 鈴木一臣, 早川聡, 尾坂明義, Van Meerbeek Bart

歯科材料・器械 24 ( 5 ) 338 - 338 2005.9

Large-scale preparation of ordered titania nanorods with enhanced photocatalytic activity Reviewed

JM Wu, TW Zhang, YW Zeng, S Hayakawa, K Tsuru, A Osaka

LANGMUIR 21 ( 15 ) 6995 - 7002 2005.7

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

A titania layer with ordered nanostructures is expected to be of high photocatalytic activity due mainly to its high specific surface area. In the present work, large-area films with ordered titania nanorods were deposited on titanium substrates through a solution approach, The nanorods, with the phase composition of a mixture of anatase and rutile, grew on top of a condensed anatase interlayer along mainly the rutile [001]-axis. The photocatalytic activity was evaluated by decomposing rhodamine B in water and compared with the general sol-gel derived titania films and a commercial DP-25 titania coating. It is found that the as-deposited titania nanorods exhibited extremely high initial photocatalytic activity but declined to a poor value after the consumption of beneficial oxidative peroxo complexes coordinated to Ti(IV). A subsequent thermal treatment eliminated such complexes but at the same time improved the crystallinity of the titania nanorods. The photocatalytic activity of the thermally treated titania nanorods was stable and significantly higher than that of the sol-gel derived film and commercial DP-25 coating.

DOI： 10.1021/la0500272

An organic-inorganic hybrid scaffold for the culture of HepG2 cells in a bioreactor Reviewed

K Kataoka, Y Nagao, T Nukui, Akiyama, I, K Tsuru, S Hayakawa, A Osaka, N Huh

BIOMATERIALS 26 ( 15 ) 2509 - 2516 2005.5

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

Much interest has recently been shown in the potential utility of bioartificial liver (BAL) as a bridge support for patients and as a module for experimental purposes. A radial-flow bioreactor (RFB), one of the perfused bed/scaffold-type bioreactors, enables a highly functional three-dimensional culture as BAL. The functional capacity of bioreactors depends not only on their mechanistic structures but also on scaffolds packed in them. In the present study, we examined the possible utility of a new porous organic-inorganic-hybrid scaffold in an RFB. The scaffold was made from tetraethoxysilane (TEOS) and polydimethylsiloxane (PDMS) by a sol-gel method using sieved sucrose particles as a porogen. In the porous TEOS-PDMS hybrid scaffold, human hepatocellular carcinoma cells (HepG2) proliferated actively and formed cell clusters more efficiently than they did in a polyvinyl-alcohol scaffold. When cultivated in PDMS-TEOS, HepG2 cells secreted a similar tothree-fold greater amount of albumin than that secreted in a monolayer culture. For potential application of BAL to pharmacological studies and future clinical use, it is essential to develop a method to propagate liver cells that maintain highly specific functions. The present results indicate that PDMS-TEOS may be a promising scaffold for developing such functional culture methods. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biomaterials.2004.07.012

Preparation of aluminum oxide-hybridized hydroxyapatite powder by the sol-gel method Reviewed

E Fuji, K Kawabata, H Yoshimatsu, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 113 ( 1315 ) 241 - 244 2005.3

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

Hydroxyapatite powders (HAp; Ca-10(PO4)(6)(OH)(2)) hybridized with 0-5 mass% Al2O3 were prepared from calcium hydroxide and di-ammonium hydrogenphosphate by a wet chemical synthesis. Ethylacetoacetate Aluminum Diisopropoxide (Al(OC3H7)(2) (C6H9O3)) was used as a source for aluminum oxide. The obtained powders were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) specific surface area measurement, and magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR). The X-ray diffraction patterns showed no Al2O3-peaks irrespective of Al2O3 content, suggesting that the Al2O3-hybridized HAp powders were single phase. The Al2O3-hybridized HAp powder had larger specific surface area. According to MAS-NMR analysis, it was considered that the aluminum element existed as aluminum oxide, it was not substituted for the Ca2+, PO43-, or OH- ions.

In vitro cytocompatibility of MG63 cells on chitosan-organosiloxane hybrid membranes Reviewed

Y Shirosaki, K Tsuru, S Hayakawa, A Osaka, MA Lopes, JD Santos, MH Fernandes

BIOMATERIALS 26 ( 5 ) 485 - 493 2005.2

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

Chitosan-silicate hybrids were synthesized using gamma-glycidoxypropyltrimethoxysilane (GPSM) as the agent for cross-linking the chitosan chains. CaCl2 was introduced in the hybrids in expectation that it would improve cell adhesion and differentiation of the hybrid surfaces. Fourier-transform infrared (FT-IR) spectroscopy and Si-29 CP-MAS NMR spectroscopy were used to analyze the structures of the hybrids. Cytocompatibility of the hybrids was investigated in terms of proliferation of an osteoblastic cell line, MG63. The adhesion and proliferation of the osteoblastic cells cultured on the Surface of a chitosan-GPSM hybrid without calcium were similar to those on a control Culture plate, and were better than those on a chitosan membrane. The ALP activity of the cells cultured on this hybrid was higher than that on the chitosan membrane. Contrary to expectations, the incorporation of calcium ions into the hybrids did not improve cell attachment and proliferation on their surfaces. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biomaterials.2004.02.056

Formation of Titania submicron-scale rod arrays on titanium substrate and in vitro biocompatibility Reviewed

S Hayakawa, YX Liu, K Okamoto, K Tsuru, A Osaka

Nanoscale Materials Science in Biology and Medicine 845 149 - 154 2005

Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings) Publisher：MATERIALS RESEARCH SOCIETY

Titania submicron-scale rod arrays were fabricated on metallic titanium (alpha-Ti) surfaces by coating a layer of sodium tetraborale on titanium substrates and subsequent thermal treatment. Thin-film X-ray diffraction analysis indicated that the sodium terraborate gave rutile (TiO2: PDF# 21-1276) submicron-scale rod arrays. The rods in the arrays are parallel to each other in the grain of metallic titanium surface. The titania submicron-scale rod arrays deposited apatite within 7 days after being soaked in a simulated body fluid, indicating that the rod arrays exhibit in vitro bioactivity.

Preparation of aluminum oxide-hybridized hydroxyapatite powder by the sol-gel method Reviewed

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

Journal of the Ceramic Society of Japan 113 ( 1315 ) 241 - 244 2005

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

Hydroxyapatite powders (HAp
Ca10(PO4) 6(OH)2) hybridized with 0-5 mass % Al2O 3 were prepared from calcium hydroxide and di-aminonium hydrogenphosphate by a wet chemical synthesis. Ethylacetoacetate Aluminum Diisopropoxide (Al(OC3H7)2(C6H 9O3)) was used as a source for aluminum oxide. The obtained powders were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) specific surface area measurement, and magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR). The X-ray diffraction patterns showed no Al2O3-peaks irrespective of Al2O3 content, suggesting that the Al2O 3-hybridized HAp powders were single phase. The Al2O 3-hybridized HAp powder had larger specific surface area. According to MAS-NMR analysis, it was considered that the aluminum element existed as aluminum oxide, it was not substituted for the Ca2+, PO 4 3-, or OH- ions.

DOI： 10.2109/jcersj.113.241

Mechanism of Apatite Formation on a Sodium Silicate Glass in a Simulated Body Fluid Reviewed

Satoshi Hayakawa, Kanji Tsuru, Chikara Ohtsuki, Akiyoshi Osaka

Journal of the American Ceramic Society 82 ( 8 ) 2155 - 2160 2004.12

Potassium titanate nanorod arrays grown on titanium substrates and their in vitro bioactivity Reviewed

YX Liu, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 112 ( 1312 ) 634 - 640 2004.12

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

A novel approach to fabricating highly-oriented, nm-scale potassium titanate K2Ti6O13 rod arrays on titanium substrates was demonstrated. The fabrication process was template-free, and simply involved coating the titanium substrates with pulverized potassium metaborate and its derivatives, and subsequent heating at 700degreesC for 5 h. When the samples were soaked in hot water, the coating layers were readily removed, leaving an array of titanate crystallites on the titanium substrates. Even the slightest change in the composition of the potassium borates resulted in various microstructures, while K2O (.) 1.03B(2)O(3) yielded highly-oriented nanorod arrays of K2Ti6O13. Bioactivity of the as-achieved nanorod arrays was proved by the deposition of apatite in simulated body fluid (SBF: Kokubo solution). When soaked in SBF, the K2Ti6O13 nanorod arrays deposited apatite within one day accompanying the release of potassium ions from the crystallites into SBF and the arrays were covered with apatite layers in three days. Ion exchange between the potassium ions in the crystal and calcium ions in SBF is proposed as the mechanism operative to favor the deposition of apatite.

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