研究者詳細 - 早川　聡

MISC - 早川　聡

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分子構造を知る（２）（NMR）－固体NMRによる無機材料の構造解析― 招待

早川聡

セラミックス 59 ( 1 ) 36 - 41 2024年1月

交流電解ゾル-ゲル反応によるシリカゲルへの酵素固定化と活性評価

吉岡朋彦, 谷口功治, 片岡卓也, 早川聡

日本セラミックス協会年会講演予稿集(Web) 2024 2024年

バイオセラミックスの最新の研究動向と将来展望

橋本雅美, 澤村武憲, 早川聡

セラミックス 51 ( 12 ) 836 - 840 2016年

The State of Art of Research and Development in Bioceramics

Masami Hashimoto, Takenori Sawamura, Satoshi Hayakawa

CERAMICS JAPAN BULLETIN OF THE CERAMICS SOCIETY OF JAPAN 51 ( 12 ) 836 - 840 2016年

In vitro degradation behavior of hydroxyapatite

S. Hayakawa

Hydroxyapatite (HAp) for Biomedical Applications 85 - 105 2015年2月

記述言語：英語出版者・発行元：Elsevier Ltd

This chapter discusses in vitro degradation behaviors of calcium phosphate particles, such as nano-crystalline hydroxyapatite (HAp) and ion-substituted HAp synthesized by the wet-chemical processing method, and how their microstructure affects their initial dissolution profiles and kinetics. The chapter reviews several in vitro evaluation techniques for biodegradability of calcium phosphate ceramics and several models representing dissolution profiles and kinetics. The chapter then discusses the relationship between the heterogeneous structure of nano-crystalline HAp and the initial dissolution behaviors in acidic buffer solution.

DOI： 10.1016/B978178242033000004-3

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NMR structural characterization of Mg-containing nano-apatite

Satoshi Hayakawa, Toshiisa Konishi, Tomohiko Yoshioka, Eiji Fujii, Kouji Kawabata

Key Engineering Materials 631 57 - 60 2015年

記述言語：英語出版者・発行元：Trans Tech Publications Ltd

Nano-meter scale Ca-deficient hydroxyapatite (nano-apatite) is a potential candidate as artificial bone substitute materials owing to its similarity to the bone with respect to composition, morphology and osteoclastic degradation or adsorbent materials for blood purification therapy to remove pathogenic substances. The initial biodegradation behaviors, the initial cell-material interaction and the protein adsorption properties of nano-apatite must depend on the microstructure. The purpose of this study is the preparation of nano-apatite particles and their structural characterization by using X-ray diffraction (XRD) and solid-state NMR spectroscopy. The nano-apatite particles were prepared by precipitation processing method, and the effects of magnesium ions on the precipitation of calcium phosphate were examined, because Mg ions are well-known to play a role of inhibition of crystal growth. The addition of Mg ions led to the precipitation of nano-meter scale Ca-deficient apatite crystals having 1.33-1.63 of the molar ratio (Mg+Ca)/P. NMR analyses showed that the microstructure of Mg•HAp particles can be explained by a crystalline HAp core covered with a thin amorphous hydrated calcium phosphate layer.

DOI： 10.4028/www.scientific.net.KEM.631.57

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USE OF INTER-FIBRIL SPACES AMONG ELECTROSPUN FIBRILS AS ION-FIXATION AND NANO-CRYSTALLIZATION

Yuki Shirosaki, Satoshi Hayakawa, Yuri Nakamura, Hiroki Yoshihara, Akiyoshi Osaka, Artemis Stamboulis

ADVANCES IN BIOCERAMICS AND POROUS CERAMICS VII 35 33 - 38 2015年

記述言語：英語出版者・発行元：AMER CERAMIC SOC

When solution of a polymer with some inorganic ions is electrospun, the polymer fibrils will be elongated within the spinning direction and those ions are held in the inter-fibril spaces. When those electrospun fibers are calcined, ceramic fibers will be obtained. The present study has attempted to employ such spaces formed in poly(vinyl alcohol) (PVA) as nano- or micro-reactor spaces for precipitation of nano-crystalline particles. Exposing the spun PVA mats to ammonia vapor fixed metal ions in the form of hydroxide and, induced apatitic calcium phosphate crystallites when the precursor solution involved calcium and hydrogen orthophosphate ions.

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Preparation of α-Tricalcium Phosphate Powders Surface-modified with Inositol Phosphate for Cement Fabrication

Toshiisa Konishi, Michiyo Honda, Tomohiko Yoshioka, Satoshi Hayakawa, Mamoru Aizawa

Key Engineering Materials 631 113 - 118 2015年

記述言語：英語

We have previously developed biodegradable β-tricalcium phosphate (β-TCP) cement based on the chelate-setting mechanism of inositol phosphate (IP6). The β-TCP cement powder for the cement fabrication was prepared via a novel powder preparation process, in which the starting β-TCP powders were prepared by simultaneous ball-milling and surface-modification in the IP6 solution. In the present study, the novel powder preparation process was applied to an α-TCP powder, and effect of milling time and beads size for ball-milling on the material properties of the a-TCP powders was investigated. The α-TCP powder ball-milled in 1000 ppm IP6 solution for 4 h with 2 mm-diameter beads was composed of single phase α-TCP with the smallest particle size of 2.2 um. Dissolution of 4 h-milled α-TCP powder was approximately twice higher than that of starting α-TCP powder before ball-milling. The α-TCP powder with high dissolution property prepared via the novel powder preparation process is potential candidate for fabrication of the chelate-setting cement.

DOI： 10.4028/www.scientific.net.KEM.631.113

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ジルコニア表面に対するリン酸モノマー処理の検討

長岡紀幸, 玉田宜之, 入江正郎, 吉原久美子, 吉田靖弘, 西川悟郎, 丸尾幸憲, 松本卓也, 皆木省吾, 早川聡

日本歯科理工学会誌 32 ( 5 ) 354 - 354 2013年9月

Sol-Gel Preparation of Silica-Based Nano-Fibers for Biomédical Applications

Song Chen, Hiroki Yoshihara, Nobutaka Hanagata, Yuki Shirosaki, Mark Blevins, Yuri Nakamura, Satoshi Hayakawa, Artemis Stamboulis, Akiyoshi Osaka

Biomaterials Science: Processing, Properties and Applications III 242 55 - 62 2013年8月

記述言語：英語

© 2013 The American Ceramic Society. All rights reserved. Silica nanotube sponges and solid silica fiber mats were fabricated using a collagen and electrospun poly(vinylalcohol) as the templates via the sol-gel route. In vitro reassembled collagen fibrils were treated in the Stöber sol-gel precursor mixture of tetraethoxysilane (TEOS), ethanol, water, and ammonia to produce the silica-coated collagen fibrils. The electrospun PVA fiber mats were soaked in the Stöber type as well as acid-catalyzed silica oligomer sol from TEOS. Those were calcined to yield apparently silica nano- or micro-fibers, but transmission and scanning electron microscope observations showed that the Stöber sol treatment resulted in silica nano- or micro-fibers with hollow structure, or nanotubes (silica NTs), while the acid-catalyzed sol yielded solid fibrous mats.

DOI： 10.1002/9781118751015.ch7

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UV-Irradiation modifies chemistry of anatase layer associated with in vitro apatite nucleation

Keita Uetsuki, Shinsuke Nakai, Yuki Shirosaki, Satoshi Hayakawa, Akiyoshi Osaka

Ceramic Engineering and Science Proceedings 33 79 - 84 2013年4月

Anatase layer was derived on pure titanium substrates by the H 2O2 treatment and calcination, on which UV was irradiated in air (UVa) and in ultra pure water (UVw). The effects of the UV irradiation on in vitro apatite formation in Kokubo's simulated body fluid were interpreted in terms of the modified chemistry of the anatase layer. The UVa treatment reduced apatite formation while the contrary effects were observed for the UVw treatment. From Ols X-ray photoelectron spectroscopic (XPS) analysis, those results were correlated to the change in the relative amount of Ti-OH (basic TiOH) and Ti-O(H)-Ti (acidic Ti-OH). Combining the XPS analysis and the apatite growth characteristics, i.e., the number and size of the semi-spherical particles and their surface-coverage, derived a plausible model: proper assembly of those sites (Ti-OH and Ti-O(H)-Ti) that collect both calcium and phosphate ions together should only give rise to induction of apatite nucleation.

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Heterogeneous structure of hydroxyapatite and in vitro degradability

Satoshi Hayakawa, Yuki Shirosaki, Akiyoshi Osaka, Christian Jäger

Ceramic Engineering and Science Proceedings 33 49 - 56 2013年4月

Hydroxyapatite (HAp) particles were synthesized by two processing methods such as solid-state reaction and wet chemical reaction, and were characterized in terms of their chemical composition, disordered structure and in vitro biodegradability. XRD revealed that the prepared HAp particles were composed of single phase HAp, while 1D and 2D solid-state NMR analysis showed that the prepared HAp particles consisted of not only crystalline HAp but also disordered phase. The in vitro biodegradability was discussed by using a structure model for nano-crystalline HAp, in which the nano-crystals consist of a crystalline HAp core covered with a disordered surface layer (core-shell model).

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Nerve regeneration by using of chitosan-silicate hybrid porous membranes

Yuki Shirosaki, Satoshi Hayakawa, Akiyoshi Osaka, José D. Santos, Ana C. Maurício

Key Engineering Materials 529-530 ( 1 ) 361 - 364 2013年

記述言語：英語

The treatment of peripheral nerve injuries is still one of the most challenging tasks in neurosurgery, as functional recovery is rarely satisfactory in these patients. The concept behind the use of biodegradable nerve guides is that no foreign material should be left in place after the device has fulfilled its task, so as to spare a second surgical intervention. In a previous study, flexible and biodegradable chitosan-γ-glycidoxypropyltrimethoxysilane (GPTMS) hybrid membranes exhibited better cytocompatibility in terms of osteoblastic cells than chitosan membrane. Porous chitosan hybrid membranes, derived by freeze-drying the hybrid gels, showed that the cells were attached and proliferated both on the surface and into pores. The aim of the present study was to evaluate the influence of these chitosan hybrid membranes in terms of their inflammatory response and remodeling of connective tissue during wound-healing processes before use as a periphery nerve graft. The porous chitosan hybrid membranes showed good biocompatibility and improved posttraumatic axonal regrowth and functional recovery. © (2013) Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/KEM.529-530.361

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Heterogeneous structure of hydroxyapatite and in vitro biodegradability

Satoshi Hayakawa, Yuki Shirosaki, Akiyoshi Osaka, Christian Jäger

Key Engineering Materials 529-530 ( 1 ) 70 - 73 2013年

記述言語：英語

Hydroxyapatite (HAp) particles were synthesized by solid-state reaction and wet chemical reaction, and were characterized in terms of their chemical composition, disordered structure and in vitro biodegradability. An X-ray diffraction study revealed that the prepared HAp particles were composed of single phase HAp, while 1D and 2D solid-state NMR analysis showed that they consisted of not only crystalline HAp but also a disordered phase. An in vitro biodegradability test showed that wet chemically derived HAp particles were degraded quicker than commercially available HAP-100. The in vitro biodegradability was discussed by using a structure model for nano-crystalline HAp, in which the nano-crystals consist of a crystalline HAp core covered with a disordered surface layer (core-shell model). Although the specific surface area was the predominant factor on the rate of Ca ion dissolution, the disordered surface layer enhanced the release of Ca ions in the initial stage within 1 min, while the crystalline core of HAp also gave different release rate of Ca ions, depending on the chemical distribution in the P (V) environment. © (2013) Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/KEM.529-530.70

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Sol-Gel Preparation of HAp-Coated Silica Macrospheres from Water Glass and Their Protein Adsorption

Jie Li, Yuki Shirosaki, Satoshi Hayakawa, Artemis Stamboulis, Akiyoshi Osaka

BIOCERAMICS 24 529-530 637 - + 2013年

記述言語：英語出版者・発行元：TRANS TECH PUBLICATIONS LTD

Silica gel macrospheres of 2 similar to 4 mm in size, and wrapped with Ca-alginate chelate film were prepared as the substrate for hydroxyapatite coating layer, using water glass as the silica source. Those Ca-SiO2 macrospheres were soaked in a 1:1 (volume) mixture of ethanol and 0.1 M Na2HPO4 to deposit hydroxyapatite layer (HAp-SiO2 macrospheres). Adsorption of bovine serum albumin and egg lysozyme on those Ca-SiO2 and HAp-SiO2 macrospheres under physiological pH (7.2) was well correlated to the Langmuir-type adsorption equation. The electrostatic interactions between the protein molecules and those macrospheres well interpret the adsorption isotherms, while the mesopores in the Ca-SiO2 contributed to some extent. A multi-layer adsorption model was proposed.

DOI： 10.4028/www.scientific.net/KEM.529-530.637

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In vitro cytocompatibility of microspheres derived from chitosan-silicate hybrids

Yuki Shirosaki, Kohei Okamoto, Satoshi Hayakawa, Akiyoshi Osaka

2013 INTERNATIONAL SYMPOSIUM ON MICRO-NANOMECHATRONICS AND HUMAN SCIENCE (MHS) 2013年

記述言語：英語出版者・発行元：IEEE

Microsphere-based therapy is used to allow drug release to treat the critical site through the choice and formulation of variations drug-polymer combinations. They are also used to control the release of insoluble drug by the biodegradability of polymer. Chitosan is one of the candidates for the polymer matrix because their biodegradability and biocompatibility. Recently, we prepared and characterized the inorganic-organic hybrid derived from chitosan and siloxane units. This hybrid showed the excellent biocompatibility for the osteoblastic cells, fibroblastic cells, and nerve cells, etc. In this study, the microspheres were prepared from this hybrid using the microfluidic systems. The biodegradability, drug releasing behavior and cytocompatibility were investigated.

DOI： 10.1109/MHS.2013.6710442

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Advanced Ceramic Science and Technology in the Western Pacific Rim Area Preface

Akiyoshi Osaka, Yoko Suyama, Akira Kishimoto, Nobuhito Imanaka, Tokuro Nanba, Satoshi Hayakawa

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 120 ( 1407 ) 2012年11月