Faculty Profiles - HAYAKAWA Satoshi

Hydroxy carbonate apatite: Synthesis, blood compatibility and adsorption of specific pathogenic proteins

In vitro biological reactivity of porous chitosan-organosiloxane hybrids

Yuki Shirosaki, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka

The 20th International Congress on Glass 2004

化学ベクトルセラミックス〜培養細胞機能をコントロールする多孔質ゼラチン-シリケートハイブリッド

都留寛治, 早川聡, 尾坂明義

バイオマテリアル-生体材料- Vol.21, No.5, 389頁〜395頁 2003

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

BIOCERAMICS: MATERIALS AND APPLICATIONS IV 147 111 - 119 2003

Language：English Publisher：AMER CERAMIC SOC

Hydroxy-carbonate apatite (CAp) compositions containing carbonate ions from 0 to 10.9 wt% were synthesized by a wet chemical method. Infrared analysis revealed that carbonate ions were substituted both PO43- and OH- sites. The introduction of CO32- ion into the hydroxyapatite lattice led to an increase in specific surface area and surface charge density. Blood clotting properties were not affected by the contact with CAp samples. The adsorption behavior of proteins was investigated by contacting CAp with model saline containing bovine serum albumin (BSA) and beta(2)-microglobulin (beta(2)-MG). The selectivity against beta(2)-MG increased with increase in the amount of carbonate ions. As surface charge density increased with increase in the amount of carbonate ions, surface charge density played an important role in selective adsorption of beta(2)-MG, but not a sole factor.

Blood compatibility of metal oxide layers on stainless-steel

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

POLYMER/METAL INTERFACES AND DEFECT MEDIATED PHENOMENA IN ORDERED POLYMERS 734 327 - 332 2003

Language：English Publisher：MATERIALS RESEARCH SOCIETY

We examined blood compatibility of titanium oxide layer on stainless-steel (SUS316L). The oxide layers with varied thickness were yielded on SUS316L plates by dip-coating of sol-gel solution starting from tetraethyltitanate. The blood compatibility was evaluated in term of platelet adhesion using platelet rich plasma. With increase in the thickness of the oxide layer, the number of adherent platelets decreased rapidly, reached minimum around 150nm. This indicated that the thickness of titanium oxide layer affected platelet adhesion.

Cytocompatibility on silicone modified with organoalkoxysilane due to emulsion polymerization

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

BIOCERAMICS 15 240-2 687 - 690 2003

Language：English Publisher：TRANS TECH PUBLICATIONS LTD

gamma-Methacryloxypropyltrimethoxysilane (gamma-MPS) molecules were grafted on silicone elastomer by emulsion polymerization. Fibroblast and osteoblastic cells were cultured to examine cytocompatibility of the grafted surface. A greater number of cells grew on the grafted silicone, even forming a cell layer, than on the original silicone. Moreover, the cultured cells were agglomerated on the latter though they adhered well. Thus the gamma-MPS grafting was concluded to improve cytocompatibility of silicone.

Blood compatibility of stainless-steel and titanium immobilized with alginic acid layers

T Yoshioka, K Tsuru, S Hayakawa, A Osaka

POLYMER/METAL INTERFACES AND DEFECT MEDIATED PHENOMENA IN ORDERED POLYMERS 734 333 - 338 2003

Language：English Publisher：MATERIALS RESEARCH SOCIETY

gamma-Aminopropyltriethoxysilane (,gamma-APS) was grafted on stainless-steel and titanium substrates, and subsequently alginic acid layer was immobilized on them. Their surfaces were characterized with X-ray photoelectron spectroscopy (XPS) and contact angle measurement. Blood compatibility of thus obtained substrates was evaluated in terms of both the number of the adhered platelets and blood clotting factors for plasma contacted with the substrates such as active partial thromboplastin time (PTT), prothrombin time (PT), and amount of fibrinogen (Fib). The steel and titanium substrates with alginic acid layer did not affect blood clotting factors. In vitro platelet adhesion assay indicated that those substrates adhered less number of platelets than non-treated substrates. Hence the alginic acid immobilization leads to blood compatible surfaces.

Biomimetic apatite deposition on titanium substrates treated with low concentrations of H2O2 solutions

K Shibata, K Tsuru, S Hayakawa, A Osaka

BIOCERAMICS 15 240-2 55 - 58 2003

Language：English Publisher：TRANS TECH PUBLICATIONS LTD

Titanium substrates were provided with ability of biomimetic apatite deposition in a simulated body fluid by means of chemical treatment and subsequent thermal treatment. Examined were the effects of the chemical treatment time, the concentration and pH conditions of the H2O2 solutions on formation of bioactive titania gel layer and in vitro bioactivity. The optimum process consist of 6 mass% H2O2 treatment at 60 degreesC for 3-6 h and subsequent thermal treatment at 400 degreesC for lh. Reactions between the titanium substrates and H2O2 involved titania gel formation and Ti (IV) dissolution. Each reaction rates well related with the concentration and pH of the H2O2 solutions.

Response to osteoblastic cells of bioactive organic-inorganic hybrid

Y Aburatani, T Uchida, Y Shirosaki, K Tsuru, S Hayakawa, A Osaka

BIOCERAMICS 15 240-2 683 - 686 2003

Language：English Publisher：TRANS TECH PUBLICATIONS LTD

Organically modified silicate gels were synthesized starting from ploy(dimethylsiloxane), tetraethoxysilane, calcium nitrate, and colloidal silica through sol-gel processing. In vitro apatite deposition on the colloidal silica containing hybrids in a simulated body fluid of the Kokubo recipe was confirmed, indicating they were bioactive. Cell proliferation for the hybrid gels with the colloidal silica was better than the colloidal silica free gels. The cells cultured for 7 days on the hybrid gels with colloidal silica expanded their pseudopodium and were well attached. In contrast, the cells were hardly observable on the colloidal silica free gels. Thus, the hybrids with colloidal silica are cytocompatible as well as bioactive.

Low-temperature deposition of bioactive crystalline titania films: Effects of tantalum

JM Wu, S Hayakawa, K Tsuru, A Osaka

BIOCERAMICS 15 240-2 533 - 536 2003

Language：English Publisher：TRANS TECH PUBLICATIONS LTD

Crystalline titania films (anatase and rutile) with excellent in vitro bioactivity were deposited through interactions of titanium and hydrogen peroxide solutions containing Ta(V) ions, under a low temperature of 80 degreesC. Ta(V) ions were found to favor both the low-temperature crystallization and the formation of rutile.

Deactivation of active oxygen species due to metals and their blood compatibility

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

BIOCERAMICS 15 240-2 105 - 107 2003

Effects of Metals on Generation and Dismutation of Active Oxygen Species in Blood

Tomoya Ogawa, Kanji Tsuru, Satoshi Hayakawa, Seisuke Takashima, Akiyoshi Osaka

Archives of BioCeramics Research 2003

Bioactive titania gel derived from combined chemical and thermal treatments of titanium

S Hayakawa, K Shibata, K Tsuru, A Osaka

27TH INTERNATIONAL COCOA BEACH CONFERENCE ON ADVANCED CERAMICS AND COMPOSITES: A 24 ( 3 ) 227 - 232 2003

Language：English Publisher：AMER CERAMIC SOC

Bioactive titania gel was derived from chemical treatment of Ti substrate with dilute H2O2 solutions and subsequent thermal treatments. We examined the effects of the chemical treatment time and the concentration and pH of the H2O2 solutions on both formation of titania gel and in vitro deposition of apatite or bioactivity. The optimum treatments consisted of 6 mass% H2O2 treatment at 60 degreesC for 3-6 h and subsequent thermal treatment at 400 degreesC for 1 h. Reactions between the titanium substrates and H2O2 involved the oxidation of titanium, titania gel formation and Ti dissolution.

Low temperature synthesis of bioactive TiO2 thin film by two-step treatment

F Xiao, K Tsuru, S Hayakawa, A Osaka

BIOCERAMICS 15 240-2 537 - 540 2003

Language：English Publisher：TRANS TECH PUBLICATIONS LTD

Bioactive TiO2 films were deposited on Ti substrates by two-step treatment near room temperature. A well-crystalline TiO2 gel film was obtained on Ti by soaking in TiF4+ H2O2 Solution at 60degrees C for 24 h. Subsequent cathode polarization precipitated calcium hydroxide. Calcium carbonate appeared after samples soaking in a Kokubo simulated body fluid due to the reaction between calcium hydroxide and bicarbonate ions. Calcium hydroxide dissolved into SBF, supersaturated with calcium ions, favored apatite nucleation. Apatite thus deposited without heating the Ti substrates. This method was applicable to substrates other than Ti.

Synthesis of carbonate-hydroxy apatite and selective adsorption activity against specific pathogenic substances

Effects of Organic Molecules in the Kokuboﾕs Simulated Body Fluid on Apatite Formation on Glass and Titanium Substrates

K. Tsuru, Y. Higashi, S. Hayakawa, A. Osaka

Proc. 2nd Asian BioCeramics Symposium(ABC2002), Korea 2002

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

BIOCERAMICS 14 218-2 175 - 178 2002

Language：English Publisher：TRANS TECH PUBLICATIONS LTD

Hydroxyapatite (HAP) and carbonate-hydroxy apatite (CAP5 and CAP15) were synthesized under the flow of N-2 containing 0%, 5%, or 15% CO2 by wet chemical method, and subsequently calcined at 105-700degreesC. Infrared analysis showed that carbonate ions substituted PO43- and OH- sites. The clotting characteristics for the fresh mixed plasma contacted with the samples indicated that CAP had better blood compatibility than HAP. The protein adsorption activity was evaluated by contacting with the model saline containing bovine serum albumin (BSA) and beta2-microgloburin (beta-MG). CAP15 calcined below 600degreesC adsorbed the lowest fraction of BSA (9%) whereas it adsorbed the highest fraction of beta(2)-MG (47%). It was concluded that the selective adsorption activity against beta(2)-MG was related to the carbonate ions incorporated in hydroxyapatite.

In vitro evaluation on bone-bonding of chemically modified titanium

JM Wu, S Hayakawa, K Tsuru, A Osaka, XX Wang

BIOCERAMICS 14 218-2 141 - 144 2002

Language：English Publisher：TRANS TECH PUBLICATIONS LTD

Treatment with a hydrogen peroxide solution containing tantalum chloride followed by heating provided titanium with bioactivity where a titania gel layer derived on surface played the essential role. Effects of surface roughness and gel thickness on in vitro bioactivity were examined using the Kokubo solution. In vitro evaluation suggested enhanced interfacial bond strength between bone and Ti implants by obtaining thinner titania layer on rougher Ti surface.

Heating effect on properties of organic-inorganic hybrids containing colloidal silica particles

Y Aburatani, K Tsuru, S Hayakawa, A Osaka

BIOCERAMICS 14 218-2 445 - 448 2002

Language：English Publisher：TRANS TECH PUBLICATIONS LTD

The organic-inorganic hybrid gels were synthesized starting from poly (dimethylsiloxane)(PDMS), tetraethoxysilane (TEOS), colloidal silica and calcium nitrate (Ca(NO3)(2).4H(2)O) through sol-gel processing. The effects of heating on the mechanical properties and microstructure of the synthesized samples were investigated. The compressive strength of the synthesized samples increased by heating. The dynamic mechanical analysis of the synthesized samples showed increase of storage modulus and decrease of the loss factor, tandelta. It was suggested that the mobility of PDMS chain was restricted with the increase of PDMS-silica interaction by heating.