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Takashi Nakamura - One of the best experts on this subject based on the ideXlab platform.
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bonelike apatite formation induced on zirconia gel in a Simulated Body Fluid and its modified solutions
Journal of the American Ceramic Society, 2004Co-Authors: Masaki Uchida, Tadashi Kokubo, Hyunmin Kim, Fumiaki Miyaji, Takashi NakamuraAbstract:Formation of bonelike apatite on zirconia gel in a Simulated Body Fluid (SBF) with ion concentrations almost equal to those in human blood plasma, in modified SBF solutions to have increased pH values, and modified SBF solutions to have increased concentrations of calcium and phosphate ions has been investigated. The zirconia gel forms apatite on its surface in SBF, indicating that Zr-OH groups, abundant on the gel, act as effective apatite nucleation centers. Apatite formation is accelerated by increases in pH and in the concentration of calcium and phosphate ions, which is explained by an increase in the ionic activity product of the apatite in the SBF. These results suggest that zirconia ceramics may exhibit a bone-bonding ability by forming an apatite layer on their surfaces in the living Body when they are modified to have many Zr-OH groups on their surfaces.
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structural dependence of apatite formation on titania gels in a Simulated Body Fluid
Journal of Biomedical Materials Research Part A, 2003Co-Authors: Masaki Uchida, Tadashi Kokubo, Hyunmin Kim, Shunsuke Fujibayashi, Takashi NakamuraAbstract:The apatite-forming ability of titania gels with different structures has been investigated in a Simulated Body Fluid with ion concentrations nearly equal to those of human blood plasma. Titania gels with an amorphous structure or with an anatase or rutile structure were prepared by the sol-gel process with a subsequent heat treatment at various temperatures. The titania gels with an amorphous structure did not induce apatite formation on their surfaces in the Simulated Body Fluid, whereas gels with an anatase or rutile structure induced apatite formation on their surfaces. The deposition of apatite was more pronounced on the anatase gels than on the rutile gels. This indicates that a specific structure of titania is effective in inducing apatite formation in a Body environment. Such a specific structure was assumed in this study to be the crystalline planar arrangement in the anatase structure, which facilitates epitaxy of the apatite crystal.
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apatite forming ability of sodium containing titania gels in a Simulated Body Fluid
Journal of the American Ceramic Society, 2001Co-Authors: Masaki Uchida, Tadashi Kokubo, Hyunmin Kim, Takashi NakamuraAbstract:An essential condition for an artificial material to bond to living bone is the formation of bonelike apatite on its surface in the living Body. The bonelike apatite can be reproduced on the bone-bonding material even in an acellular Simulated Body Fluid (SBF) with ion concentrations almost equal to those of human blood plasma. In the present study, the dependence of the apatite-forming abilities of sodium-containing titania gels in a SBF on composition and structure is examined. The sodium-containing titania gels are model substances produced on the surface layer of bioactive titanium metal prepared by sodium hydroxide solution and heat treatments. When sodium-containing titania gels are immersed in the SBF, Na+ ions incorporated in the gels are exchanged with the H3O+ ions in the SBF. This ion exchange causes an accompanying increase in the pH of the SBF and increases its ionic activity product, thus providing favorable conditions for apatite nucleation on the surfaces of the gels. Nevertheless, sodium-containing titania gels that do not contain anatase do not form apatite on their surfaces. Independent of the composition, the gels form apatite on their surfaces in the SBF, specifically when they contain anatase. These results imply that the Ti-OH groups on titania, which have been proposed to be responsible for the apatite formation, are effective for apatite nucleation when they are arranged in a specific structural unit based on the anatase structure.
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revised Simulated Body Fluid
Key Engineering Materials, 2000Co-Authors: Hyunmin Kim, Toshiki Miyazaki, Tadashi Kokubo, Takashi NakamuraAbstract:Preparation of a revised Simulated Body Fluid (R-SBF) with ion concentrations, including those of Cl{sup -} and HCO{sub 3}{sup -}, equal to those of the human blood plasma was attempted. Ion concentrations of the prepared SBF were confirmed to be equal to those of the blood plasma. The concentrations were unchanged at least for 4 weeks, when the R-SBF was sealed in a polystyrene container and stored at 36.5 C. The R-SBF is believed to produce apatite with composition and structure equal to those of bone apatite, thereby being useful for in vitro assessment of bioactivity of a material and for biomimetic synthesis of bonelike apatite. (orig.)
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apatite formation on silica gel in Simulated Body Fluid effects of structural modification with solvent exchange
Journal of Materials Science: Materials in Medicine, 1998Co-Authors: Fumiaki Miyaji, Tadashi Kokubo, Kazuki Nakanishi, Naohiro Soga, Takashi NakamuraAbstract:The prerequisite for glasses and glass-ceramics to bond to living bone is the formation of biologically active bone-like apatite on their surfaces. It has been shown that even a pure silica gel forms the bone-like apatite on its surface in a Simulated Body Fluid. In the present study, pore structure of silica gels prepared by hydrolysis and polycondensation of tetraethoxysilane in an aqueous solution containing polyethylene glycol was modified by 1M HNO3, and 0.1M and 1M NH4OH solution treatments. The three kinds of resultant gels all contained large amounts of silanol groups and trisiloxane rings, but differ greatly in pore structure of nanometre pore size. Irrespective of these differences, all the gels formed the bone-like apatite on their surface in the Simulated Body Fluid. It was speculated that a certain type of structural unit of silanol groups, which is easily formed in the presence of the polyethylene glycol, is effective for the apatite formation. © 1998 Chapman & Hall
Tadashi Kokubo - One of the best experts on this subject based on the ideXlab platform.
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Simulated Body Fluid and the novel bioactive materials derived from it
Journal of biomedical materials research. Part A, 2019Co-Authors: Tadashi Kokubo, Seiji YamaguchiAbstract:Professor Larry Hench first reported that certain glasses are able to spontaneously bond to living bone in 1970. This discovery stimulated research into new kinds of bone-bonding materials. However, there were no guiding principles for this purpose, and many animals were sacrificed in the effort to establish them. The present authors proposed in 1991 that the bone-bonding capacity of a material could be evaluated by examining apatite formation on its surface in an acellular Simulated Body Fluid (SBF), without the need of performing any animal experiments. Various kinds of novel bone-bonding bioactive materials based on Ti metal and its alloys with a number of different functions have been developed using SBF. Some of these have entered clinical use as important bone-repairing materials. Without the method of SBF evaluation, these novel materials would not have been developed. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 968-977, 2019.
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Novel bioactive materials developed by Simulated Body Fluid evaluation: Surface-modified Ti metal and its alloys
Acta biomaterialia, 2016Co-Authors: Tadashi Kokubo, Seiji YamaguchiAbstract:Abstract Until the discovery of the bone-bonding activity of Bioglass by Hench et al. in the early 1970s, it had not been demonstrated that a synthetic material could bond to living bone without eliciting a foreign Body reaction. Since then, various kinds of materials based on calcium phosphate, such as sintered hydroxyapatite and β-tricalcium phosphate have also been shown to bond to living bone. Until the discovery of the bone-bonding activity of Ti metal formed with a sodium titanate surface layer by the present authors in 1996, it had not been shown that a metallic material could bond to living bone. Since then, various kinds of surface-modified Ti metal and its alloys have been found to bond to living bone. Until the discovery of the osteoinduction of porous hydroxyapatite by Yamasaki in 1990, it was unknown whether a synthetic material could induce bone formation even in muscle tissue. Since then, various kinds of porous calcium phosphate ceramics have been shown to induce osteoinduction. Until the discovery of osteoinduction induced by a porous Ti metal formed with a titanium oxide surface layer by Fujibayashi et al. in 2004, it had been unclear whether porous metals would be able to induce osteoinduction. These novel bioactive materials have been developed by systematic research into the apatite formation that occurs on surface-modified Ti metal and its related materials in an acellular Simulated Body Fluid (SBF) having ion concentrations almost equal to those of human blood plasma. Some of the novel bioactive materials based on Ti metal are already in clinical use or clinical trials, such as artificial hip joints and spinal fusion devices. In the present paper, we review how these novel bioactive materials based on Ti metal have been developed based on an evaluation of apatite formation in SBF. Without the SBF evaluation, these novel bioactive materials would most likely never have been developed. Statement of Significance On the basis of systematic study of apatite formation on a material in a Simulated Body Fluid, various kinds of novel bioactive materials possessing not only bone-bonding activity and but also various other functions such as bone growth promotion, antibacterial activity and osteoinduction have been developed. Some of them are already successfully applied to clinical applications or trials for artificial hip joints and spinal fusion devices. It is shown in the present paper how these novel bioactive materials have been developed.
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bonelike apatite formation induced on zirconia gel in a Simulated Body Fluid and its modified solutions
Journal of the American Ceramic Society, 2004Co-Authors: Masaki Uchida, Tadashi Kokubo, Hyunmin Kim, Fumiaki Miyaji, Takashi NakamuraAbstract:Formation of bonelike apatite on zirconia gel in a Simulated Body Fluid (SBF) with ion concentrations almost equal to those in human blood plasma, in modified SBF solutions to have increased pH values, and modified SBF solutions to have increased concentrations of calcium and phosphate ions has been investigated. The zirconia gel forms apatite on its surface in SBF, indicating that Zr-OH groups, abundant on the gel, act as effective apatite nucleation centers. Apatite formation is accelerated by increases in pH and in the concentration of calcium and phosphate ions, which is explained by an increase in the ionic activity product of the apatite in the SBF. These results suggest that zirconia ceramics may exhibit a bone-bonding ability by forming an apatite layer on their surfaces in the living Body when they are modified to have many Zr-OH groups on their surfaces.
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apatite forming ability of carboxyl group containing polymer gels in a Simulated Body Fluid
Biomaterials, 2003Co-Authors: Masakazu Kawashita, Tadashi Kokubo, M Nakao, Masahiko Minoda, Toshiyuki Beppu, Takeaki Miyamoto, T NakamuraAbstract:Abstract Carboxymethylated chitin, gellan gum, and curdlan gels were soaked in a Simulated Body Fluid (SBF) having ion concentrations nearly equal to those of human blood plasma. Some of the gels had been soaked in a saturated Ca(OH) 2 solution, while others had not. The carboxymethylated chitin and gellan gum gels have carboxyl groups, while the curdlan gel has hydroxyl groups. None of the gels formed apatite on their surfaces in the SBF when they had not been subjected to the Ca(OH) 2 treatment, whereas the carboxymethylated chitin and gellan gum gels formed apatite on their surfaces when they had been subjected to the Ca(OH) 2 treatment. The curdlan gel did not form an apatite deposit even after the Ca(OH) 2 treatment. Apatite formation on the carboxymethylated chitin and gellan gum gels was attributed to the catalytic effect of their carboxyl groups for apatite nucleation, and acceleration of apatite nucleation from released Ca 2+ ions. This result provides a guiding principle for obtaining apatite-organic polymer fiber composites. This composite is expected to have an analogous structure to that of natural bone.
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structural dependence of apatite formation on titania gels in a Simulated Body Fluid
Journal of Biomedical Materials Research Part A, 2003Co-Authors: Masaki Uchida, Tadashi Kokubo, Hyunmin Kim, Shunsuke Fujibayashi, Takashi NakamuraAbstract:The apatite-forming ability of titania gels with different structures has been investigated in a Simulated Body Fluid with ion concentrations nearly equal to those of human blood plasma. Titania gels with an amorphous structure or with an anatase or rutile structure were prepared by the sol-gel process with a subsequent heat treatment at various temperatures. The titania gels with an amorphous structure did not induce apatite formation on their surfaces in the Simulated Body Fluid, whereas gels with an anatase or rutile structure induced apatite formation on their surfaces. The deposition of apatite was more pronounced on the anatase gels than on the rutile gels. This indicates that a specific structure of titania is effective in inducing apatite formation in a Body environment. Such a specific structure was assumed in this study to be the crystalline planar arrangement in the anatase structure, which facilitates epitaxy of the apatite crystal.
Sasha Omanovic - One of the best experts on this subject based on the ideXlab platform.
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corrosion behaviour of polypyrrole coated we43 mg alloy in a modified Simulated Body Fluid solution
Corrosion Science, 2018Co-Authors: M Ascencio, M Pekguleryuz, Sasha OmanovicAbstract:Abstract The corrosion behaviour of PPy-coated WE43 Mg alloy in a Simulated Body Fluid solution with daily electrolyte renewal is investigated by electrochemical, hydrogen evolution and analytical techniques. It is shown that the PPy coating effectively contributes to a decrease in the corrosion rate of WE43 Mg alloy and production of H 2 gas. An increase in the PPy coating protective properties observed after every electrolyte renewal is attributed to: 1) a decrease in the coating conductivity by the adsorption of CO 2 species, and 2) substrate/coating decoupling due to uncompensated coating positive charging and misalignment of the substrate and coating Fermi levels.
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An investigation of the corrosion mechanisms of WE43 Mg alloy in a modified Simulated Body Fluid solution: The effect of electrolyte renewal
Corrosion Science, 2015Co-Authors: M Ascencio, M Pekguleryuz, Sasha OmanovicAbstract:Abstract The effect of daily electrolyte renewal on the corrosion mechanisms and kinetics of WE43 Mg alloy in a modified Simulated Body Fluid (m-SBF) is investigated by electrochemical, hydrogen evolution, analytical and surface characterization techniques. It is shown that by performing electrolyte renewal, physiological control of corrosion products and concentration of relevant electrolyte components such as calcium, phosphate and carbonate species, can be better emulated. Electrolyte renewal affects the corrosion mechanism by promoting partial dissolution of the corrosion layer and increasing mass transport, thereby delaying the increase in the corrosion layer protective ability and the occurrence of localized corrosion.
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an investigation of the corrosion mechanisms of we43 mg alloy in a modified Simulated Body Fluid solution the influence of immersion time
Corrosion Science, 2014Co-Authors: M Ascencio, M Pekguleryuz, Sasha OmanovicAbstract:Abstract The corrosion mechanisms and kinetics of WE43 Mg alloy in a modified Simulated Body Fluid (m-SBF) are investigated by electrochemical, hydrogen evolution and analytical techniques. The changes in the impedance response over time are related to four corrosion stages involving the formation of a partially protective corrosion layer and adsorption of Mg intermediates, formation of an inner passive MgO layer with increasing coverage over time, rupture of the corrosion layer and lateral growth of stable pits. ATR-FTIR, XRD and XPS results show the presence of an amorphous carbonated apatite/Mg(OH) 2 mixed corrosion layer.
Yong Wang - One of the best experts on this subject based on the ideXlab platform.
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improve corrosion resistance of magnesium in Simulated Body Fluid by dicalcium phosphate dihydrate coating
Materials Science and Engineering: C, 2009Co-Authors: Yong Wang, Mei Wei, Jiacheng GaoAbstract:Abstract A dicalcium phosphate dihydrate (DCPD) coating composed of bar-shaped crystals was deposited on the surface of magnesium in order to slow down the corrosion rate of the substrate. The corrosion resistance of the DCPD-coated specimens was evaluated in a Simulated Body Fluid (SBF) with uncoated specimens as a control. Time-dependent characteristics of specimens and the corresponding SBF were analyzed at 3, 5, 7, 14 and 21 days of immersion. Less weight loss and pH increase were observed for the coated group than the uncoated group. The coating was intact after 3 days of immersion although its dissolution was manifested by XRD examination. Noticeable DCPD dissolution occurred at the 5th day accompanied by a temporary increase in Ca and P concentrations in SBF which otherwise kept decreasing. Despite the dissolution of the coating, some DCPD particles were still observed on the surface of the substrate after 21 days of immersion. In contrast to the coated specimens, a porous layer of Mg(OH)2 was formed on the surface of uncoated specimens at the 5th day of immersion. It was found that the corrosion rate of the coated group was substantially lower than that of the control.
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corrosion process of pure magnesium in Simulated Body Fluid
Materials Letters, 2008Co-Authors: Yong Wang, Mei Wei, Jiacheng Gao, Yan ZhangAbstract:The chemical and physical processes of magnesium in Simulated Body Fluid (SBF) were investigated. The corrosion rate of magnesium was measured after 3, 5, 7, 14 and 21 days of immersion, respectively. It was found that the corrosion rate decreased with increasing immersion time, while the pH of SBF changed inversely. Network-like cracks and pits were the main damages resulting from corrosion, and the localized buildup of chloride ions was the major cause of pit formation.
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evaluation of cyto toxicity and corrosion behavior of alkali heat treated magnesium in Simulated Body Fluid
Surface & Coatings Technology, 2004Co-Authors: Longchuan Li, Yong WangAbstract:Abstract Compared to other popular metallic biomaterials, magnesium has many advantages, which include high specific strength-to-mass ratio, non-toxicity and similar elastic modulus to that of human bone. However, the knowledge gap in corrosion resistance in physiological environment has prevented it from being a substitute for human hard tissues. In this paper, preliminary corrosion tests on magnesium specimens in Simulated Body Fluid (SBF) with and without Cl − ions have been investigated. Cytotoxicity tests were then carried out for developing a new biomaterial. The corrosion results showed that alkali and heat-treated magnesium has relatively high corrosion resistance in SBF, compared to untreated samples. Calcium-phosphate apatites were detected on the treated samples after they had been soaked in SBF for 14 days. In cytotoxicity tests, no signs of morphological changes on cells or inhibitory effect on cell growth were detected.
Masaki Uchida - One of the best experts on this subject based on the ideXlab platform.
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simple surface modification of poly e caprolactone for apatite deposition from Simulated Body Fluid
Biomaterials, 2005Co-Authors: Ayako Oyane, Masaki Uchida, Cleo Choong, J T Triffitt, John H JonesAbstract:Abstract Poly( e -caprolactone) (PCL) with a bone-like apatite layer bound to its surface could be useful as a scaffold for tissue engineering applications. In the present study, the surface of PCL was treated with aqueous NaOH to introduce carboxylate groups onto the surface. The NaOH-treated material was subsequently dipped in aqueous CaCl 2 and K 2 HPO 4 ·3H 2 O alternately three times to deposit apatite nuclei on the surface. The surface-modified material successfully formed a dense and uniform bone-like surface apatite layer after incubation for 24 h in Simulated Body Fluid with ion concentrations approximately equal to those of human blood plasma.
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bonelike apatite formation induced on zirconia gel in a Simulated Body Fluid and its modified solutions
Journal of the American Ceramic Society, 2004Co-Authors: Masaki Uchida, Tadashi Kokubo, Hyunmin Kim, Fumiaki Miyaji, Takashi NakamuraAbstract:Formation of bonelike apatite on zirconia gel in a Simulated Body Fluid (SBF) with ion concentrations almost equal to those in human blood plasma, in modified SBF solutions to have increased pH values, and modified SBF solutions to have increased concentrations of calcium and phosphate ions has been investigated. The zirconia gel forms apatite on its surface in SBF, indicating that Zr-OH groups, abundant on the gel, act as effective apatite nucleation centers. Apatite formation is accelerated by increases in pH and in the concentration of calcium and phosphate ions, which is explained by an increase in the ionic activity product of the apatite in the SBF. These results suggest that zirconia ceramics may exhibit a bone-bonding ability by forming an apatite layer on their surfaces in the living Body when they are modified to have many Zr-OH groups on their surfaces.
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structural dependence of apatite formation on titania gels in a Simulated Body Fluid
Journal of Biomedical Materials Research Part A, 2003Co-Authors: Masaki Uchida, Tadashi Kokubo, Hyunmin Kim, Shunsuke Fujibayashi, Takashi NakamuraAbstract:The apatite-forming ability of titania gels with different structures has been investigated in a Simulated Body Fluid with ion concentrations nearly equal to those of human blood plasma. Titania gels with an amorphous structure or with an anatase or rutile structure were prepared by the sol-gel process with a subsequent heat treatment at various temperatures. The titania gels with an amorphous structure did not induce apatite formation on their surfaces in the Simulated Body Fluid, whereas gels with an anatase or rutile structure induced apatite formation on their surfaces. The deposition of apatite was more pronounced on the anatase gels than on the rutile gels. This indicates that a specific structure of titania is effective in inducing apatite formation in a Body environment. Such a specific structure was assumed in this study to be the crystalline planar arrangement in the anatase structure, which facilitates epitaxy of the apatite crystal.
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apatite forming ability of sodium containing titania gels in a Simulated Body Fluid
Journal of the American Ceramic Society, 2001Co-Authors: Masaki Uchida, Tadashi Kokubo, Hyunmin Kim, Takashi NakamuraAbstract:An essential condition for an artificial material to bond to living bone is the formation of bonelike apatite on its surface in the living Body. The bonelike apatite can be reproduced on the bone-bonding material even in an acellular Simulated Body Fluid (SBF) with ion concentrations almost equal to those of human blood plasma. In the present study, the dependence of the apatite-forming abilities of sodium-containing titania gels in a SBF on composition and structure is examined. The sodium-containing titania gels are model substances produced on the surface layer of bioactive titanium metal prepared by sodium hydroxide solution and heat treatments. When sodium-containing titania gels are immersed in the SBF, Na+ ions incorporated in the gels are exchanged with the H3O+ ions in the SBF. This ion exchange causes an accompanying increase in the pH of the SBF and increases its ionic activity product, thus providing favorable conditions for apatite nucleation on the surfaces of the gels. Nevertheless, sodium-containing titania gels that do not contain anatase do not form apatite on their surfaces. Independent of the composition, the gels form apatite on their surfaces in the SBF, specifically when they contain anatase. These results imply that the Ti-OH groups on titania, which have been proposed to be responsible for the apatite formation, are effective for apatite nucleation when they are arranged in a specific structural unit based on the anatase structure.
