Faculty Profiles - HAYAKAWA Satoshi

Papers - HAYAKAWA Satoshi

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Preparation of organotitanium molecular layers for biomedical applications Reviewed

T Yoshioka, K Tsuru, S Hayakawa, A Osaka

MATERIALS SCIENCE & ENGINEERING C-BIOMIMETIC AND SUPRAMOLECULAR SYSTEMS 24 ( 6-8 ) 901 - 905 2004.12

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

We prepared an organotitanium molecular layer on stainless-steel (SUS316L) substrates, and evaluated its blood compatibility in terms of blood-clotting time and fibrinogen adsorption properties. Titanium methacrylate triisopropoxide (TMT) was used as the organotitanium molecule. The surface was characterized by contact angle measurement toward distilled water and Fourier transform infrared spectroscopy using a reflection absorption method (FT-IRRAS). The obtained organotitanium molecular layer had little effects on the blood-clotting times such as active partial thromboplastin time (PTT) and prothrombin time (PT). Bovine fibrinogen adsorption on the layer was examined from the absorbance of amide I peak in FT-IRRAS spectra. The organotitanium molecular layer reduced the amount of adsorbed fibrinogen compared with stainless-steel. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.msec.2004.08.035

Synthesis of bioactive and porous organic-inorganic hybrids for biomedical applications Reviewed

Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

Journal of Sol-Gel Science and Technology 32 ( 1-3 ) 201 - 205 2004.12

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

Bioactivity has been exhibited by a limited range of ceramics since the invention of Bioglass®. Recently, some bioactive polymeric organic-inorganic hybrids were introduced, including not only organically modified silicates (Ormosils) synthesized from polydimethylsiloxane (PDMS) and tetraethoxysilane but also those with gelatin and 3-glycidoxypropyl-tremethoxysilane. Preparation of the bulk and porous hybrids and their polymeric structures analyzed by Si NMR spectroscopy were presented. In vitro bioactivity or apatite deposition in a simulated body fluid of the Kokubo recipe were also described for those hybrids. Freeze-drying techniques introduced porosity (up to 90%) and pores extending in a preferred direction. © 2004 Kluwer Academic Publishers.

DOI： 10.1007/s10971-004-5789-1

Topotaxial nucleation and growth of TiO2 submicron-scale rod arrays on titanium substrates via sodium tetraborate glass coating Reviewed

YX Liu, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 112 ( 1310 ) 567 - 571 2004.10

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

A novel approach to fabricate sub-pm scale arrays is demonstrated with the growth of rutile TiO2 on titanium substrates. The fabrication process is template-free, simply involving coating of the titanium substrate with sodium tetraborate glass, Na2O (.) 2B(2)O(3): when the glass coating was removed by dissolution in distilled water at 80degreesC for about 5 h, random or well-ordered submicron-scale rod arrays of rutile were left on the substrate. A glass phase topotaxial (GPT) nucleation and growth mechanism is thought to operate in the crystal growth process.

In vitro bioactive nano-crystalline TiO2 layers grown at glass-coating/titanium interface Reviewed

YX Liu, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 112 ( 1308 ) 452 - 457 2004.8

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

A new approach is presented to prepare a rutile layer on titanium substrates. According to this approach, pulverized glass, composed of 3CaO - 4B(2)O(3) - 3TiO(2), is first developed on the substrate, heated up to 700 to 850degreesC, and then removed by soaking in hot water. During the heating process, rutile grew at the glass coating-substrate interface to form nano-sized crystallites. The rutile layer induced apatite formation within 3 d when soaked in simulated body fluid of the Kokubo recipe. Such in vitro bioactivity was attributed to many Ti-OH groups on the crystallite surface derived from hydrolysis of bonds at the crysiallite-flux (matrix) interface like (rutile) -Ti-O-B or Ti-O-Ca- (the borate matrix).

Synthesis of blood compatible PDMS-based organic-inorganic hybrid coatings Reviewed

T Yabuta, K Tsuru, S Hayakawa, A Osaka

JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY 31 ( 1-3 ) 273 - 276 2004.8

Language：English Publishing type：Research paper (scientific journal) Publisher：KLUWER ACADEMIC PUBL

PDMS- TiO2 hybrid coating sols were prepared from silanol- terminated polydimethylsiloxane and titanium tetraisopropoxide through sol- gel process. The coating sols were developed on stainless steel substrate with dip- coating technique. The surface structure of the hybrid coating was characterized by Fourier transform infrared ( FT- IR) analysis, contact angle, and surface free energy on the hybrid coating. Blood compatibility was also evaluated in terms of blood clotting time and platelet adhesion. The hybrid coatings have high contact angles and low surface free energies compared to coating- free metal surface. The blood clotting properties were not affected by the hybrid coatings but the platelet adhesion was depressed to less than 1/ 20 as much as that for the coating- free substrate.

DOI： 10.1023/B:JSST.0000048002.65187.3a

Platelet adhesion on titanium oxide gels: effect of surface oxidation Reviewed

S Takemoto, T Yamamoto, K Tsuru, S Hayakawa, A Osaka, S Takashima

BIOMATERIALS 25 ( 17 ) 3485 - 3492 2004.8

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

The correlations between titanium oxide layers on oxidized titanium (Ti) substrates and platelet adhesion were examined. Ti substrates were prepared by three different oxidation methods: the first one was treated with hydrogen peroxide (H2O2) solution, the second one was heated in air at moderate temperatures, and the third one was processed with both H2O2 and heating. The titanium oxide layers formed on the Ti substrates were characterized by wettability, chemical composition, thickness, and crystal phase. The platelet adhesion on these oxide layers was examined and correlated to the characterizations of the surface layers. The number of adhesive platelets seemingly correlated with the contact angle towards distilled water, because the number increased close to 70-80degrees of the contact angle. The effect of surface oxidation on platelet adhesion was examined in detail and it was found that the composition and thickness of the oxide layer influenced platelet adhesion rather than wettability. Thick titanium oxide layers formed on Ti substrates by heating displayed less platelet adhesion than thin oxide layers on untreated Ti substrates. The largest number of adhesive platelets was found on H2O2-oxidized substrates; the substrates found on amorphous titanium oxide contained the Ti-peroxide radical species. The number of platelets, on the other hand, could hardly be observed on Ti substrates treated with H2O2 and subsequently heated above 300 degreesC. The titanium oxide layer on the substrate was thick and we found it to consist of only a few radical species. That is, the effect of heat treatment accelerates the growth of the oxide layer, and decomposes or decreases the number of radical species. Ti substrates with H2O2 and heat treatment above 300 degreesC held the least number of platelets, and were concluded to be the most inhibitory for platelet adhesion. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biomaterials.2003.10.070

Selective protein adsorption and blood compatibility of hydroxy-carbonate apatites. Reviewed International journal

Shinji Takemoto, Yuko Kusudo, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka, Seisuke Takashima

Journal of biomedical materials research. Part A 69 ( 3 ) 544 - 51 2004.6

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

We examined the blood compatibility and protein adsorption on hydroxyapatite and hydroxy-carbonate apatite. Those apatites were synthesized under a 0, 5, or 15% CO(2)-containing N(2) atmosphere by a wet-chemical method with a strong ammonia alkali solution of calcium nitrate and diammonium hydrogen phosphate (5:3 in molar ratio) and subsequent calcination in the range of 105-700 degrees C. From infrared (IR) analysis, the carbonate ions substituted both phosphate ions and hydroxyl ions in the hydroxyapatite lattice; the intensities of IR bands assignable to phosphate ions and hydroxyl ions were reduced on calcinations. The specific surface areas of synthesized apatites decreased with increasing calcination temperature. Blood-clotting properties were evaluated in terms of active partial thromboplastin time, prothrombin time, and the amount of fibrinogen for the plasma in contact with the apatites, indicating that all the apatites barely influenced the blood clotting system. The apatites were in contact with a solution containing both bovine serum albumin (BSA) and beta(2)-microglobulin (beta(2)-MG), and the amounts of those proteins adsorbed on them were examined: the amount of absorbed BSA and beta(2)-MG gradually increased with the calcination temperature below 500 degrees C, while it showed a sudden increase when more than 600 degrees C. Hydroxy-carbonate apatite synthesized under a 15% CO(2)-containing N(2) atmosphere and calcined below 400 degrees C had the greatest selectivity in adsorbing beta(2)-MG. Thus, a higher selectivity for beta(2)-MG adsorption was empirically correlated to carbonate ions incorporated in the hydroxyapatite lattice.

Selective protein adsorption and blood compatibility of hydroxy-carbonate apatites Reviewed

S Takemoto, Y Kusudo, K Tsuru, S Hayakawa, A Osaka, S Takashima

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 69A ( 3 ) 544 - 551 2004.6

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-LISS

We examined the blood compatibility and protein adsorption on hydroxyapatite and hydroxy-carbonate apatite. Those apatites were synthesized under a 0, 5, or 15% CO2-containing N-2 atmosphere by a wet-chemical method with a strong ammonia alkali solution of calcium nitrate and diammonium hydrogen phosphate (5:3 in molar ratio) and subsequent calcination in the range of 105-700degreesC. From infrared (IR) analysis, the carbonate ions substituted both phosphate ions and hydroxyl ions in the hydroxyapatite lattice; the intensities of IR bands assignable to phosphate ions and hydroxyl ions were reduced on calcinations. The specific surface areas of synthesized apatites decreased with increasing calcination temperature. Blood-clotting properties were evaluated in terms of active partial thromboplastin time, prothrombin time, and the amount of fibrinogen for the plasma in contact with the apatites, indicating that all the apatites barely influenced the blood clotting system. The apatites were in contact with a solution containing both bovine serum albumin (BSA) and beta(2)-microglobulin (beta(2)-MG), and the amounts of those proteins adsorbed on them were examined: the amount of absorbed BSA and beta(2)-MG gradually increased with the calcination temperature below 500degreesC, while it showed a sudden increase when more than 600degreesC. Hydroxy-carbonate apatite synthesized under a 15%, CO2-containing N-2 atmosphere and calcined below 400degreesC had the greatest selectivity in adsorbing beta(2)-MG. Thus, a higher selectivity for beta(2)-MG adsorption was empirically correlated to carbonate ions incorporated in the hydroxyapatite lattice. (C) 2004 Wiley Periodicals, Inc.

DOI： 10.1002/jbm.a.30039

Crystallisation studies of biodegradable CaO-P2O5 glass with MgO and TiO2 for bone regeneration applications Reviewed

AG Dias, K Tsuru, S Hayakawa, MA Lopes, JD Santos, A Osaka

GLASS TECHNOLOGY 45 ( 2 ) 78 - 79 2004.4

Language：English Publishing type：Research paper (scientific journal) Publisher：SOC GLASS TECHNOLOGY

CaO-P2O5 glass ceramics with small additions of MgO and TiO2 were prepared in the ortho and pyrophosphate regions by powder sintering and crystallisation through heat treatment at different temperatures determined from, differential thermal analysis (DTA). The glass ceramics were analysed by x-ray diffraction (XRD) and it was observed that alpha- and beta-Ca2P2O7 were the first phases to precipitate in the parent glass matrix at a temperature of 681degreesC, followed by CaTi4(PO4)(6) and TiP2O7 at temperatures between 703 and 725degreesC The beta-Ca2P2O7 and CaTi4(PO4)(6) phases are usually considered as biocompatible and bioactive and, therefore, these glass ceramics seem to show good potential for bone regeneration applications.

In vitro bioactive nano-crystalline TiO2 layers grown at glass-coating/titanium interface Reviewed

Yongxing Liu, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

Journal of the Ceramic Society of Japan 112 ( 1308 ) 452 - 457 2004

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

A new approach is presented to prepare a rutile layer on titanium substrates. According to this approach, pulverized glass, composed of 3CaO·4B2O3·3TiO2, is first developed on the substrate, heated up to 700 to 850°C, and then removed by soaking in hot water. During the heating process, rutile grew at the glass coating-substrate interface to form nano-sized crystallites. The rutile layer induced apatite formation within 3 d when soaked in simulated body fluid of the Kokubo recipe. Such in vitro bioactivity was attributed to many Ti-OH groups on the crystallite surface derived from hydrolysis of bonds at the crystallite-flux (matrix) interface like (rutile) -Ti-O-B or Ti-O-Ca-(the borate matrix).

DOI： 10.2109/jcersj.112.452

Topotaxial nucleation and growth of TiO2 submicron-scale rod arrays on titanium substrates via sodium tetraborate glass coating Reviewed

Yongxing Liu, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

Journal of the Ceramic Society of Japan 112 ( 1310 ) 567 - 571 2004

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

A novel approach to fabricate sub-μm scale arrays is demonstrated with the growth of rutile TiO2 on titanium substrates. The fabrication process is template-free, simply involving coating of the titanium substrate with sodium tetraborate glass, Na2O · 2B2O 3: when the glass coating was removed by dissolution in distilled water at 80°C for about 5 h, random or well-ordered submicron-scale rod arrays of rutile were left on the substrate. A glass phase topotaxial (GPT) nucleation and growth mechanism is thought to operate in the crystal growth process.

DOI： 10.2109/jcersj.112.567

In vitro Platelet Adhesion and Protein Adsorption of Biomedical Implant Modified with Polysaccharide Reviewed

Tomohiko Yoshioka, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

Transactions of the Materials Research Society of Japan 2004

TITANIA DERIVED FROM COMBINED CHEMICAL AND THERMAL TREATMENTS OF TITANIUM: IN VITRO APATITE FORMING ABILITY Reviewed

Akiyoshi Osaka, Kanji Tsuru, Satoshi Hayakawa

Phosphorus Research Bulletin 2004

Low-temperature preparation of anatase and rutile layers on titanium substrates and their ability to induce in vitro apatite deposition Reviewed

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

Journal of the American Ceramic Society 87 ( 9 ) 1635 - 1642 2004

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

Surface modification of titanium and its alloys to induce apatite deposition within a short period is of practical importance in clinical applications. In this study, titanium substrates were treated with hydrogen peroxide solutions at low temperatures to yield titania layers consisting of anatase and rutile. Those titania layers, regardless of the fraction of anatase and rutile, were bioactive to induce deposition of apatite in Kokubo's simulated body fluid within 24 h. The bioactivity was attributed to both the epitaxial effect and the abundant Ti-OH group of the titania layer.

DOI： 10.1111/j.1551-2916.2004.01635.x

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

Yongxing Liu, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

Journal of the Ceramic Society of Japan 112 ( 1312 ) 634 - 640 2004

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

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 700°C 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·1.03B2O 3 yielded highly-oriented nanorod arrays of K2Ti 6O13. 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.

DOI： 10.2109/jcersj.112.634

Bioactivity of metallic biomaterials with anatase layers deposited in acidic titanium tetrafluoride solution Reviewed

JM Wu, F Xiao, S Hayakawa, K Tsuru, S Takemoto, A Osaka

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE 14 ( 12 ) 1027 - 1032 2003.12

Language：English Publishing type：Research paper (scientific journal) Publisher：KLUWER ACADEMIC PUBL

A simple and versatile treatment was developed to provide various metallic biomaterials such as Ti, NiTi, Ta and SUS 316L stainless steel with in vitro bioactivity or ability to deposit carbonate-incorporated apatite in a simulated body fluid (Kokubo solution). A well-crystallized anatase layer deposited on the metallic biomaterials surfaces after soaking them at 60degreesC for 24 h in an aqueous solution of titanium tetrafluoride (40 mM) whose pH was adjusted to 1.9 with HCl;. The as-coated anatase layers did not deposit apatite. When heated at 300degreesC they were so bioactive as to deposit apatite within 5 day(s) in the Kokubo solution. The trace amount of fluorine weakly bound in the as-coated anatase layers was suggested to be one of the factors that suppressed the bioactivity. (C) 2003 Kluwer Academic Publishers.

DOI： 10.1023/B:JMSM.0000003998.37583.d7

Apatite deposition on thermally and anodically oxidized titanium surfaces in a simulated body fluid Reviewed

XX Wang, W Yan, S Hayakawa, K Tsuru, A Osaka

BIOMATERIALS 24 ( 25 ) 4631 - 4637 2003.11

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

By application of a special specimen set-LIP, thermally oxidized titanium specimen pairs were found able to deposit apatite oil the contact surfaces after soaking for 7 days in the simulated body fluid (SBF) of Kokubo's recipe. The specimens oxidized at 400degreesC and 500degreesC showed the highest ability of apatite deposition. Both increase and decrease in oxidation temperature front this range caused the apatite deposition ability to decrease. The specimen without treatment failed to deposit any apatite. Specimens anodically oxidized in electrolytes of H3PO4, H2SO4 and acetic acid exhibited very low ability of apatite deposition. Furthermore, the specimen thermally oxidized at 400degreesC was even able to help the surfaces of PTFE and silicone deposit apatite in the PTFE-Ti and silicone-Ti pairs. This in vitro experimental results indicated that the difference in apatite deposition among various titanium oxides does exist and can be distinguished by applying the present specimen set-up. The mechanism of the apatite deposition on the contact surfaces was discussed in relation to the passive dissolution of titanium in SBF. The release of titanium hydroxide and OH- ions from the titanium surfaces and their accumulation inside the confined space between the two contact surfaces were suggested to be responsible for the apatite deposition. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/S0142-9612(03)00357-0

Structure and biomineralization of calcium silicate glasses containing fluoride ions Reviewed

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

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 111 ( 10 ) 762 - 766 2003.10

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

The in vitro bioactivity, in terms of apatite-forming ability, of calcium silicate glasses containing 10 mol% fluoride ions in the NaF-CaO-SiO2 system was examined by soaking in Kokubo's simulated body fluid (SBF) at 36.5degreesC 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 by Si-29 magic angle spinning-nuclear magnetic 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 . 45SiO(2) was lower than that of 50CaO . 50SiO(2). 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/SiO2 between the glasses.

Sol-gel preparation of blood-compatible titania as an adsorbent of bilirubin Reviewed

T Asano, S Takemoto, K Tsuru, S Hayakawa, A Osaka, S Takashima

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 111 ( 9 ) 645 - 650 2003.9

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

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 tetraethylorthotitanate and calcining up to 705degreesC 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.

In vitro apatite deposition on titania film derived from chemical treatment of Ti substrates with an oxysulfate solution containing hydrogen peroxide at low temperature Reviewed

F Xiao, K Tsuru, S Hayakawa, A Osaka

THIN SOLID FILMS 441 ( 1-2 ) 271 - 276 2003.9

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

Thin titania film consisting of anatase and rutile was deposited on Ti substrates when soaked in a TiOSO4/H2O2 solution and aged in hot water. H2O2 corroded the Ti substrates, yielded a porous surface, and kept the solution from peptization. Thicker titania layers were formed in favor of both a greater supersaturation of Ti(IV) in the solution and a higher concentration of hydrated Ti(IV) derived by the corrosion of Ti and the hydrolysis of TiOSO4. The effects of aging in hot water were accounted for as they caused structural relaxation of the surface layer involving a rearrangement of Ti-OH and eliminating residual species like peroxide ions. Those titania layers were thus favored to deposit apatite when the Ti substrates were placed under a body environment, i.e. soaked in a simulated body fluid of Kokubo's recipe. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0040-6090(03)00913-1

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