Faculty Profiles - HAYAKAWA Satoshi

Papers - HAYAKAWA Satoshi

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Biomedical applications of sol-gel nanocomposites Reviewed

Song Chen, Satoshi Hayakawa, Yuki Shirosaki, Nobutaka Hanagata, Akiyoshi Osaka

Sol-Gel Nanocomposites 167 - 190 2014.1

Language：English Publishing type：Part of collection (book) Publisher：Springer New York

This chapter introduces nanocomposites of silica, titania, calcium phosphates, biologically active glasses, and their polymer-modified derivatives with meso- and macro-porous, nanotubular, or hollow nanoparticle-type structures that have been prepared via the sol-gel routes. Their applications for delivering drugs and DNAs, tissue-materials interactions, and tissue regeneration are briefly described.

DOI： 10.1007/978-1-4939-1209-4_7

The role of the chemical composition of monetite on the synthesis and properties of alpha-tricalcium phosphate Reviewed

Jo Duncan, James F. MacDonald, John V. Hanna, Yuki Shirosaki, Satoshi Hayakawa, Akiyoshi Osaka, Janet M. S. Skakle, Iain R. Gibson

MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS 34 123 - 129 2014.1

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

There has been a resurgence of interest in alpha-tricalcium phosphate (alpha-TCP), with use in cements, polymer composites and in bi- and tri-phasic calcium phosphate bone grafts. The simplest and most established method for preparing alpha-TCP is the solid state reaction of monetite (CaHPO4) and calcium carbonate at high temperatures, followed by quenching.
In this study, the effect of the chemical composition of reagents used in the synthesis of alpha-TCP on the local structure of the final product is reported and findings previously reported pertaining to the phase composition and stability are also corroborated. Chemical impurities in the monetite reagents were identified and could be correlated to the calcium phosphate products formed; magnesium impurities favoured the formation of beta-TCP, whereas single phase alpha-TCP was favoured when magnesium levels were low. Monetite synthesised in-house exhibited a high level of chemical purity; when this source was used to produce an alpha-TCP sample, the alpha-polymorph could be obtained by both quenching and by cooling to room temperature in the furnace at rates between 1 and 10 degrees C/min, thereby simplifying the synthesis process. It was only when impurities were minimised that the 12 phosphorus environments in the alpha-TCP structure could be resolved by P-31 nuclear magnetic resonance; samples containing chemical impurity showed differing degrees of line-broadening. Reagent purity should therefore be considered a priority when synthesising/characterising the alpha-polymorph of TCP. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.msec.2013.08.038

Challenges for Nerve Repair Using Chitosan-Siloxane Hybrid Porous Scaffolds Reviewed

Yuki Shirosaki, Satoshi Hayakawa, Akiyoshi Osaka, Maria A. Lopes, Jose D. Santos, Stefano Geuna, Ana C. Mauricio

BIOMED RESEARCH INTERNATIONAL 2014 7 2014

Language：English Publisher：HINDAWI PUBLISHING CORPORATION

The treatment of peripheral nerve injuries remains one of the greatest challenges of neurosurgery, as functional recover is rarely satisfactory in these patients. Recently, biodegradable nerve guides have shown great potential for enhancing nerve regeneration. A major advantage of these nerve guides is that no foreign material remains after the device has fulfilled its task, which spares a second surgical intervention. Recently, we studied peripheral nerve regeneration using chitosan-gamma-glycidoxypropyltrimethoxysilane (chitosan-GPTMS) porous hybrid membranes. In our studies, these porous membranes significantly improved nerve fiber regeneration and functional recovery in rat models of axonotmetic and neurotmetic sciatic nerve injuries. In particular, the number of regenerated myelinated nerve fibers and myelin thickness were significantly higher in rat treated with chitosan porous hybrid membranes, whether or not they were used in combination with mesenchymal stem cells isolated from the Wharton's jelly of the umbilical cord. In this review, we describe our findings on the use of chitosan-GPTMS hybrids for nerve regeneration.

DOI： 10.1155/2014/153808

Sol-Gel-Derived Silicate Nano-Hybrids for Biomedical Applications Reviewed

Kanji Tsuru, Yuki Shirosaki, Satoshi Hayakawa, Akiyoshi Osaka

BIOLOGICAL & PHARMACEUTICAL BULLETIN 36 ( 11 ) 1683 - 1687 2013.11

Language：English Publishing type：Research paper (scientific journal) Publisher：PHARMACEUTICAL SOC JAPAN

Organic-inorganic hybrids of poly(dimethyl siloxane), gelatin, and chitosan with such silanes as tetraethoxysilane and 3-glycidoxytriethoxysilane are derived via the sol-gel routes. Their biomedical applications are discussed from biomimetic deposition of bone-like apatite, cell culture, and in vivo behavior.

DOI： 10.1248/bpb.b13-00526

Preparation of injectable hydroxyapatite/collagen paste using sodium alginate and influence of additives Reviewed

Taira Sato, Akinori Kochi, Yuki Shirosaki, Satoshi Hayakawa, Mamoru Aizawa, Akiyoshi Osaka, Masanori Kikuchi

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 121 ( 1417 ) 775 - 781 2013.9

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

Preparation of injectable hydroxyapatite/collagen bone-like nanocomposite (HAp/Col) paste utilizing sodium alginate (Na-Alg) and influence of additives on the paste properties were investigated. The HAp/Col at the HAp and collagen mass ratio of 80:20 synthesized by a simultaneous titration method was pelletized to 100-212 mu m. The HAp/Col powder and that treated with 100mM CaCl2 (Ca-HAp/Col) were used as starting powders. A paste was prepared by mixing of the starting powder and Na-Alg solution at one of several powder/liquid ratios. The paste was directly injected into 100mM CaCl2 solution to confirm setting capability, and examined a viscosity, hardening behavior, compressive strength and decay property. In addition, the paste supplemented with an organic acid or a calcium compound as an additive was also prepared to examine influences of the additive on paste properties. The organic acid was chosen from citric, succinic, malic, lactic and glycolic acids, and the calcium compound was chosen from Ca(OH)(2), Ca(CO)(3), CaSO4 center dot 0.5H(2)O and calcium citrate.
The prepared paste was set by direct injection to 100mM CaCl2 solution. The suitable mixing conditions of the paste were a P/L ratio of 0.6 at the 90:10 mass ratio of Ca-HAp/Col and solution of low viscous Na-Alg. All additives increased the paste viscosity; however, the mechanisms were different between organic acids and calcium compounds. Organic acids rapidly decreased pH to form Alg gel by deposition of Alg. Contrarily, calcium compounds supplied Ca2+ ions to form egg-box structure for gelation of Alg, and the reaction depended on solubility of compound. Additives also increased decaying time but could not realize anti-decay in the present conditions. The results suggested that the HAp/Col injectable paste can be utilized in rapid prototyping materials and might be good candidate for injectable artificial bone with further improvement in anti-decay property. (C)2013 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.121.775

Adhesive interfacial interaction affected by different carbon-chain monomers Reviewed

Kumiko Yoshihara, Yasuhiro Yoshida, Noriyuki Nagaoka, Satoshi Hayakawa, Takumi Okihara, Jan De Munck, Yukinori Maruo, Goro Nishigawa, Shogo Minagi, Akiyoshi Osaka, Bart Van Meerbeek

DENTAL MATERIALS 29 ( 8 ) 888 - 897 2013.8

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

Objectives. The functional monomer 10-methacryloxydecyl dihydrogen phosphate (10-MDP), recently used in more self-etch adhesives, chemically bonds to hydroxyapatite (HAp) and thus tooth tissue. Although the interfacial interaction of the phosphoric-acid functional group of 10-MDP with HAp-based substrates has well been documented, the effect of the long carbon-chain spacer of 10-MDP on the bonding effectiveness is far from understood.
Methods. We investigated three phosphoric-acid monomers, 2-methacryloyloxyethyl dihydrogen phosphate (2-MEP), 6-methacryloyloxyhexyl dihydrogen phosphate (6-MHP) and 10-MDP, that only differed for the length of the carbon chain, on their chemical interaction potential with HAp and dentin, this correlatively using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Commercial 6-MHP and 10-MDP containing adhesives were investigated as well.
Results. XRD revealed that on HAp only 10-MDP produced monomer-calcium salts in the form of 'nano-layering', while on dentin all monomers produced 'nano-layering', but with a varying intensity in the order of 10-MDP > 6-MHP > 2-MEP. TEM confirmed that 10-MDP formed the thickest hybrid and adhesive layer. XRD and TEM revealed 'nano-layering' for all commercial adhesives on dentin, though less intensively for the 6-MHP containing adhesive than for the 10-MDP ones.
Significance. It is concluded that not only the phosphoric-acid group but also the spacer group, and its length, affect the chemical interaction potential with HAp and dentin. In addition, the relatively strong 'etching'' effect of 10-MDP forms more stable monomer-Ca salts, or 'nano-layering', than the two shorter carbon-chain monomers tested, thereby explaining, at least in part, the better bond durability documented with 10-MDP containing adhesives. (c) 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.dental.2013.05.006

Aluminium-free glass polyalkenoate cements: ion release and in vitro antibacterial efficacy Reviewed

A. W. Wren, J. P. Hansen, S. Hayakawa, M. R. Towler

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE 24 ( 5 ) 1167 - 1178 2013.5

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

Glass polyalkenoate cements (GPCs) have exhibited potential as bone cements. This study investigates the effect of substituting TiO2 for SiO2 in the glass phase and the subsequent effect on cement rheology, mechanical properties, ion release and antibacterial properties. Glass characterization revealed a reduction in glass transition temperature (T (g) ) from 685 to 669 A degrees C with the addition of 6 mol % TiO2 (AT-2). Magic angle spinning nuclear magnetic resonance (MAS-NMR) revealed a shift from -81 ppm to -76pmm when comparing a Control glass to AT-2, indicating de-polymerization of the Si network. The incorporation of TiO2 also increased the working time (T (w) ) from 19 to 61 s and setting time (T (s) ) from 70 to 427 s. The maximum compressive strength (sigma (c) ) increased from 64 to 85 MPa. Ion release studies determined that the addition of Ti to the glass reduced the release of zinc, calcium and strontium ions, with low concentrations of titanium being released. Antibacterial testing in E. coli resulted in greater bactericidal effects when tested in aqueous broth for both titanium containing cements.

DOI： 10.1007/s10856-013-4880-y

Nucleation and growth of apatite on an anatase layer irradiated with UV light under different environmental conditions Reviewed

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

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 101 ( 3 ) 712 - 719 2013.3

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

Implant surfaces must sometimes be modified to form strong bonds to host tissues. The method of depositing an anatase layer on chemically pure titanium by chemical oxidation with H2O2 and subsequent calcination (CHT) is known to deposit apatite under physiological conditions; it thus exhibits bone-bonding ability. UV irradiation should affect the bonding ability because the CHT anatase layer would experience certain chemical modifications, such as a decrease or an increase in the number of TiOH and TiO(H)Ti sites; these sites are considered active sites for apatite nucleation. When in vitro apatite deposition was examined, using Kokubo's simulated body fluid, UV irradiation in air reduced the apatite-forming ability of the CHT anatase layer, and UV irradiation on the samples in water enhanced the ability. These results were correlated to changes in the Ti?OH and TiO(H)Ti sites, as determined by O 1s X-ray photoelectron spectroscopy. Analysis of the number and size of the semi-spherical apatite particles and their surface coverage led to a model: proper assembly of the Ti?OH and TiO(H)Ti sites should only give rise to the induction of apatite nucleation, analogous to topotaxy effects.(C) 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 712-719, 2013.

DOI： 10.1002/jbm.a.34370

Revisiting structure of silica gels from water glass: an H-1 and Si-29 MAS and CP-MAS NMR study Reviewed

Jie Li, Satoshi Hayakawa, Yuki Shirosaki, Akiyoshi Osaka

JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY 65 ( 2 ) 135 - 142 2013.2

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

The silica gels, derived from water glass solution with pH adjusted at 3.0 and 9.9, were revisited to investigate their constitution, although water glass has been studied for last tens of decades on gelation. Solid-state nuclear magnetic resonance spectroscopy was applied to the nuclei H-1 and Si-29, by the use of magic angle spinning (MAS), H-1 -> Si-29 CP-MAS (CP: cross-polarization), and modern techniques such as 2D HETCOR (two dimensional heteronuclear correlation), and variable-contact time CP techniques. Gelation time (t(gel)) showed U-letter shape dependence on pH. All gels consisted of Q(n) groups (n: 2, 3, and 4), where Q(n) stands for a silicate unite [(O-1/2)(n)Si (-O-)(4-n)] (n: 0-4). The analysis of the H-1 -> Si-29 CP kinetics and H-1-Si-29 HETCOR spectra elucidated the presence of four kinds of H-1 nuclei, i.e., those giving a peak at 6.9 ppm in chemical shift delta: H-1-OSi hydrogen bonded to H2O molecules; one at 4.3 ppm: H-1 of adsorbed water molecules, hydrogen-bonded to the silanol groups; one at 1.7 ppm: H-1-OSi confined in the gel lattice, including that forming aggregations like Si-O-H/O-Na-Si; and one at 4.2 ppm: H-1 of water molecules on the outermost hydration layer.

DOI： 10.1007/s10971-012-2917-1

Preparation of inorganic-organic hybrid membrane for peripheral nerve reconstruction Reviewed

Yuki Shirosaki, Satoshi Hayakawa, Akiyoshi Osaka, Maria A. Lopes, José D. Santos, Ana C. Maurîcio, Stefano Geuna

9th IMAPS/ACerS International Conference and Exhibition on Ceramic Interconnect and Ceramic Microsystems Technologies, CICMT 2013 173 - 176 2013.1

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-3-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. In this study, the porous chitosan-silicate hybrid membranes with non-differentiated human mesenchymal stem cells isolated from Wharton's jelly of umbilical cord were used to reconstruct the crushed peripheral nerve. Axonotmesis lesion of 3 mm was enwrapped with the hybrid membranes with or without a monolayer of non-differentiated human mesenchymal stem cells. Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks. The combination of hybrid membranes and human MSCs infiltration showed a slightly better recovery than the untreated control (the just crushed nerve). On the other hand, the hybrid membrane alone promoted the crushed peripheral nerve reconstruction. It is expected that the porous chitosan hybrid membranes is candidate for the clinical tool in peripheral nerve reconstructive surgery.

Heterogeneous structure and in vitro degradation behavior of wet-chemically derived nanocrystalline silicon-containing hydroxyapatite particles

Satoshi Hayakawa, Tomoko Kanaya, Kanji Tsuru, Yuki Shirosaki, Akiyoshi Osaka, Eiji Fujii, Koji Kawabata, Georgiana Gasqueres, Christian Bonhomme, Florence Babonneau, Christian Jaeger, Hans-Joachim Kleebe

ACTA BIOMATERIALIA 9 ( 1 ) 4856 - 4867 2013.1

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

Nanocrystalline hydroxyapatite (HAp) and silicon-containing hydroxyapatite (SiHAp) particles were synthesized by a wet-chemical procedure and their heterogeneous structures involving a disordered phase were analyzed in detail by X-ray diffractometry (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and solid-state magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The effects of heterogeneous structure on in vitro biodegradability and the biologically active Ca(II)- and Si(IV)-releasing property of SiHAp particles were discussed. The Si-29 NMR analysis revealed that the Si(IV) was incorporated in the HAp lattice in the form of Q(0) (SiO44- or HSiO43-) species, accompanied by the formation of condensed silicate units outside the HAp lattice structure, where the fraction and amount of Q(0) species in the HAp lattice depends on the Si content. The P-31 and H-1 NMR results agreed well with the XRD, TEM and FTIR results. NMR quantitative analysis results were explained by using a core-shell model assuming a simplified hexagonal shape of HAp covered with a disordered layer, where Si(IV) in Q(0) was incorporated in the HAp lattice and a disordered phase consisted of hydrated calcium phosphates involving polymeric silicate species and carbonate anions. With the increase in the Si content in the HAp lattice, the in vitro degradation rate of the SiHAps increased, while their crystallite size stayed nearly unchanged. The biologically active Ca(II)- and Si(IV)-releasing ability of the SiHAps was remarkably enhanced at the initial stage of reactions by an increase in the amount of Si(IV) incorporated in the HAP lattice but also by an increase of the amount of polymeric silicate species incorporated in the disordered phase. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.actbio.2012.08.024

HEMA Inhibits Interfacial Nano-layering of the Functional Monomer MDP Reviewed

Y. Yoshida, K. Yoshihara, S. Hayakawa, N. Nagaoka, T. Okihara, T. Matsumoto, S. Minagi, A. Osaka, K. Van Landuyt, B. Van Meerbeek

JOURNAL OF DENTAL RESEARCH 91 ( 11 ) 1060 - 1065 2012.11

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

Previous research showed that the functional monomer 10-methacryloxydecyl dihydrogen phosphate (MDP) ionically bonds to hydroxyapatite (HAp) and forms a nano-layered structure at the interface with HAp-based substrates. Such hydrophobic nano-layering is considered to contribute to the long-term durability of the bond to tooth tissue. However, dental adhesives are complex mixtures usually containing different monomers. This study investigated the effect of the monomer 2-hydroxyethylmethacrylate (HEMA) on the chemical interaction of MDP with HAp by x-ray diffraction (XRD), nuclear magnetic resonance (NMR), and quartz crystal microbalance (QCM). We examined the chemical interaction of 5 experimental MDP solutions with increasing concentrations of HEMA. XRD revealed that addition of HEMA inhibits nano-layering at the interface, while NMR confirmed that MDP remained adsorbed onto the HAp surface. QCM confirmed this adsorption of MDP to HAp, as well as revealed that the demineralization rate of HAp by MDP was reduced by HEMA. It was concluded that even though the adsorption of MDP to HAp was not hindered, addition of HEMA inhibited interfacial nano-layering. Potential consequences with regard to bond durability necessitate further research.

DOI： 10.1177/0022034512460396

Electrospun poly(vinyl alcohol) as a template of silica hollow and solid micro-fibrous mats Reviewed

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

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 120 ( 1407 ) 520 - 524 2012.11

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

Silica fiber mats were fabricated by soaking electro-spun poly(vinyl alcohol) fibril mat in NH4OH-catalyzed (Stober type) colloidal silica sol and silica oligomer solution from HCl-catalysis of the system tetraethoxysilane, ethanol, and water, followed by appropriate heat treatments. The silica fibrils from the Stober silica sol were hollow nano-tubes (NT) consisting of nano-sized silica particles, while the silica nanofibers (NF) from the acid-catalyzed sol were solid with minimal porosity. A model was proposed for the NF and NT formation processes. (C)2012 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.120.520

Use of hybrid chitosan membranes and human mesenchymal stem cells from the Wharton jelly of umbilical cord for promoting nerve regeneration in an axonotmesis rat model Reviewed

Andrea Gaertner, Tiago Pereira, Maria Joao Simoes, Paulo A. S. Armada-da-Silva, Miguel L. Franca, Rosa Sousa, Simone Bompasso, Stefania Raimondo, Yuki Shirosaki, Yuri Nakamura, Satoshi Hayakawa, Akiyoshi Osakah, Beatriz Porto, Ana Lucia Luis, Artur S. P. Varejao, Ana Colette Mauricio

NEURAL REGENERATION RESEARCH 7 ( 29 ) 2247 - 2258 2012.10

Language：English Publishing type：Research paper (scientific journal) Publisher：SHENYANG EDITORIAL DEPT NEURAL REGENERATION RES

Many studies have been dedicated to the development of scaffolds for improving post-traumatic nerve regeneration. The goal of this study was to assess the effect on nerve regeneration, associating a hybrid chitosan membrane with non-differentiated human mesenchymal stem cells isolated from Wharton's jelly of umbilical cord, in peripheral nerve reconstruction after crush injury. Chromosome analysis on human mesenchymal stem cell line from Wharton's jelly was carried out and no structural alterations were found in metaphase. Chitosan membranes were previously tested in vitro, to assess their ability in supporting human mesenchymal stem cell survival, expansion, and differentiation. For the in vivo testing, Sasco Sprague adult rats were divided in 4 groups of 6 or 7 animals each: Group 1, sciatic axonotmesis injury without any other intervention (Group 1-Crush); Group 2, the axonotmesis lesion of 3 mm was infiltrated with a suspension of 1 250-1 500 human mesenchymal stem cells (total volume of 50 mu L) (Group 2-CrushCell); Group 3, axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane covered with a monolayer of non-differentiated human mesenchymal stem cells (Group 3-CrushChitIIICell) and Group 4, axonotmesis lesion of 3 mm was enwrapped with a chitosan type III membrane (Group 4-CrushChitIII). Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks using sciatic functional index, static sciatic index, extensor postural thrust, and withdrawal reflex latency. Stereological analysis was carried out on regenerated nerve fibers. Results showed that infiltration of human mesenchymal stem cells, or the combination of chitosan membrane enwrapment and human mesenchymal stem cell enrichment after nerve crush injury provide a slight advantage to post-traumatic nerve regeneration. Results obtained with chitosan type III membrane alone confirmed that they significantly improve post-traumatic axonal regrowth and may represent a very promising clinical tool in peripheral nerve reconstructive surgery. Yet, umbilical cord human mesenchymal stem cells, that can be expanded in culture and induced to form several different types of cells, may prove, in future experiments, to be a new source of cells for cell therapy, including targets such as peripheral nerve and muscle.

DOI： 10.3969/j.issn.1673-5374.2012.29.002

Sol-gel preparation of apatite-coated silica macrospheres from water glass and their adsorption of bovine serum albumin and lysozyme Reviewed

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

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 120 ( 1405 ) 355 - 361 2012.9

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

Silica gel macrospheres were prepared from water glass as the silica source. The water glass solution was mixed with sodium alginate solution and added dropwisely to 1 M CaCl2 solution to form macrospheres with similar to 4 and 2.6 mm in diameter. Those SiO2 macrospheres were soaked in 1:1 (volume) mixture of ethanol and 0.1 M Na2HPO4 to deposit hydroxyapatite layer (HAp-SiO2 macrospheres). Bovine serum albumin (BSA) and egg lysozyme (LYZ) were adsorbed those SiO2 and HAp-SiO2 macrospheres. The amount of proteins adsorbed was well correlated to the Langmuir-type adsorption equation. The electrostatic interaction was predominant between the macrosphere surface and the protein molecules. Protein molecular entrapment in the mesopores (525 nm) was also probable for the SiO2 macrospheres but not applicable to the HAp-SiO2 ones without the mesopores. From consideration that protein molecule has a few groups with negative or positive partial charges, a multi-layer adsorption model was proposed. (c) 2012 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.120.355

Characterization of hybrid composite membrane based polymer/precursor/SiO2 Reviewed

Uma Thanganathan, Yuta Nishina, Kunio Kimura, Satoshi Hayakawa, Rambabu Bobba

MATERIALS LETTERS 81 88 - 91 2012.8

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

New class of hybrid composite was synthesized via sol-gel process with the combination of poly(vinyl alcohol) (PVA), TEOS, 3-glycidyloxypropyltrimethoxysilane (GPTMS) reacted with the cross-linking agent glutaraldehyde. The composites demonstrated a maximum high proton conductivity of 1.7 x 10(-2) S cm(-1) at 140 degrees C and a relative humidity of 50% RH. The swelling ratio was calculated in dry and wet conditions, and the composites were found capable of swelling. The structural formation of the composites was studied by techniques such as FTIR, TGA and impedance spectroscopy, and it was concluded that these PVA-SiO2/GPTMS/GA composite membranes exhibited excellent thermal, mechanical and conductivity properties. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2012.04.023

Self-assembled Nano-layering at the Adhesive Interface Reviewed

Y. Yoshida, K. Yoshihara, N. Nagaoka, S. Hayakawa, Y. Torii, T. Ogawa, A. Osaka, B. Van Meerbeek

JOURNAL OF DENTAL RESEARCH 91 ( 4 ) 376 - 381 2012.4

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

According to the 'Adhesion-Decalcification' concept, specific functional monomers within dental adhesives can ionically interact with hydroxyapatite (HAp). Such ionic bonding has been demonstrated for 10-methacryloyloxydecyl dihydrogen phosphate (MDP) to manifest in the form of self-assembled 'nano-layering'. However, it remained to be explored if such nano-layering also occurs on tooth tissue when commercial MDP-containing adhesives (Clearfil SE Bond, Kuraray; Scotchbond Universal, 3M ESPE) were applied following common clinical application protocols. We therefore characterized adhesive-dentin interfaces chemically, using x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDS), and ultrastructurally, using (scanning) transmission electron microscopy (TEM/STEM). Both adhesives revealed nano-layering at the adhesive interface, not only within the hybrid layer but also, particularly for Clearfil SE Bond (Kuraray), extending into the adhesive layer. Since such self-assembled nano-layering of two 10-MDP molecules, joined by stable MDP-Ca salt formation, must make the adhesive interface more resistant to biodegradation, it may well explain the documented favorable clinical longevity of bonds produced by 10-MDP-based adhesives.

DOI： 10.1177/0022034512437375

BMP-2-loaded silica nanotube fibrous meshes for bone generation Reviewed

Song Chen, Xuetao Shi, Hiromi Morita, Jie Li, Nobuhiro Ogawa, Toshiyuki Ikoma, Satoshi Hayakawa, Yuki Shirosaki, Akiyoshi Osaka, Nobutaka Hanagata

SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 12 ( 6 ) 2011.12

Language：English Publishing type：Research paper (scientific journal) Publisher：NATL INST MATERIALS SCIENCE

Silica nanotube fibrous meshes were fabricated as multiple functional matrices for both delivering bone morphological protein-2 (BMP-2) and supporting osteoblast attachment and proliferation. The meshes were fabricated via a collagen-templated sol-gel route and consisted of tubular silica with open ends. BMP-2 was loaded to the meshes by soaking in BMP-2 solution. The meshes effectively enabled the attachment and proliferation of osteoblast MC3T3-E1 cells and delivered bioactive BMP-2 to stimulate cell differentiation. These results demonstrate the potential use of the meshes in bone generation applications.

DOI： 10.1088/1468-6996/12/6/065003

Nanolayering of phosphoric acid ester monomer on enamel and dentin Reviewed

Kumiko Yoshihara, Yasuhiro Yoshida, Satoshi Hayakawa, Noriyuki Nagaoka, Masao Irie, Tatsuyuki Ogawa, Kirsten L. Van Landuyt, Akiyoshi Osaka, Kazuomi Suzuki, Shogo Minagi, Bart Van Meerbeek

ACTA BIOMATERIALIA 7 ( 8 ) 3187 - 3195 2011.8

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

Following the "adhesion-decalcification" concept, specific functional monomers possess the capacity to primary chemically interact with hydroxyapatite (HAp). Such ionic bonding with synthetic HAp has been demonstrated for 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), manifest as self-assembled "nanolayering". In continuation of that basic research this study aimed to explore whether nanolayering also occurs on enamel and dentin when a 10-MDP primer is applied following a common clinical application protocol. Therefore, the interaction of an experimental 10-MDP primer and a control, commercially available, 10-MDP-based primer (Clearfil SE Bond primer (C-SE), Kuraray) with enamel and dentin was characterized by X-ray diffraction (XRD), complemented with transmission electron microscopy interfacial ultrastructural data upon their reaction with enamel and dentin. In addition, XRD was used to study the effect of the concentration of 10-MDP on nanolayering on dentin. Finally, the stability of the nanolayers was determined by measuring the bond strength to enamel and dentin when a photoinitiator was added to the experimental primer or when interfacial polymerization depended solely on the photoinitiator supplied with the subsequently applied adhesive resin. XRD confirmed nanolayering on enamel and dentin, which was significantly greater on dentin than on enamel, and also when the surface was actively rubbed with the primer. Nanolayering was also proportional to the concentration of 10-MDP in the primer. Finally, the experimental primer needed the photoinitiator to obtain a tensile bond strength to dentin comparable with that of the control C-SE primer (which also contains a photoinitiator), but not when bonded to enamel. It is concluded that self-assembled nanolayering occurs on enamel and dentin, even when following a clinically used application protocol. The lower bonding effectiveness of mild self-etch adhesives to enamel should be ascribed in part to a lower chemical reactivity (nanolayering) with enamel HAP. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.actbio.2011.04.026

Effect of Disordered Structure of Boron-Containing Calcium Phosphates on their In Vitro Biodegradability Reviewed

Sabrina Barheine, Satoshi Hayakawa, Christian Jaeger, Yuki Shirosaki, Akiyoshi Osaka

JOURNAL OF THE AMERICAN CERAMIC SOCIETY 94 ( 8 ) 2656 - 2662 2011.8

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

This study proposes a new guideline for designing biodegradable apatite ceramics. Boron-containing hydroxyapatite (BHAp) particles were prepared by a high-temperature solid-state reaction processing method and were characterized in terms of their chemical composition, apatite lattice defects and in vitro biodegradability. Solid-state nuclear magnetic resonance analysis showed that boron-incorporation into hydroxyapatite (HAp) derived by thermo-chemical reactions between borate and calcium phosphate phases led to disordered phases (BCaP) of a CaO-P2O5-B2O3-OH system covering the crystalline HAp core. X-ray diffraction analysis indicated that the BCaP phase must consist mainly of a crystalline oxyboroapatite (OBAp) phase. An in vitro biodegradability test showed that BHAp degraded quicker than HAp or beta-tricalcium phosphate. The biodegradability of BHAp particles can be controlled by boron incorporation into a HAp lattice leading to the formation of a disordered OBAp phase.

DOI： 10.1111/j.1551-2916.2011.04400.x

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