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Kunio Ishikawa - One of the best experts on this subject based on the ideXlab platform.

  • “Fabrication of arbitrarily shaped carbonate apatite foam based on the interlocking process of dicalcium hydrogen Phosphate dihydrate”
    Journal of Materials Science: Materials in Medicine, 2017
    Co-Authors: Yuki Sugiura, Kanji Tsuru, Kunio Ishikawa
    Abstract:

    Carbonate apatite (CO_3Ap) foam with an interconnected porous structure is highly attractive as a scaffold for bone replacement. In this study, arbitrarily shaped CO_3Ap foam was formed from α-tricalcium Phosphate (α-TCP) foam granules via a two-step process involving treatment with acidic calcium Phosphate Solution followed by hydrothermal treatment with NaHCO_3. The treatment with acidic calcium Phosphate Solution, which is key to fabricating arbitrarily shaped CO_3Ap foam, enables dicalcium hydrogen Phosphate dihydrate (DCPD) crystals to form on the α-TCP foam granules. The generated DCPD crystals cause the α-TCP granules to interlock with each other, inducing an α-TCP/DCPD foam. The interlocking structure containing DCPD crystals can survive hydrothermal treatment with NaHCO_3. The arbitrarily shaped CO_3Ap foam was fabricated from the α-TCP/DCPD foam via hydrothermal treatment at 200 °C for 24 h in the presence of a large amount of NaHCO_3.

  • Effect of citric acid on setting reaction and tissue response to β-TCP granular cement.
    Biomedical materials (Bristol England), 2017
    Co-Authors: Naoyuki Fukuda, Kanji Tsuru, Yoshihide Mori, Kunio Ishikawa
    Abstract:

    We recently reported that when an acidic calcium Phosphate Solution is mixed with β-tricalcium Phosphate (β-TCP) granules, the resulting dicalcium Phosphate dihydrate (DCPD) crystals form bridges between the β-TCP granules, creating a set interconnected porous structure in approximately 1 min. Although this self-setting β-TCP granular cement (β-TCPGC) is useful for clinical applications, the short setting time is a key drawback for handling. In this study, the setting time of β-TCPGC was adjusted with the addition of citric acid, which is a known inhibiter of DCPD crystal growth. As the concentration of citric acid in the acidic calcium Phosphate Solution increased, the amount of DCPD formation in the set β-TCPGC decreased, and the crystal morphology of DCPD became elongated. β-TCPGC prepared with various citric acid concentrations were used as grafting material in rat calvarial bone defects to evaluate bone regeneration in vivo. Four weeks after implantation, no inflammatory reaction and approximately 20% new bone formation were observed, regardless of the presence or absence of citric acid in the liquid phase of β-TCPGC. We concluded, therefore, that citric acid might be a useful retarder of β-TCPGC setting times.

  • Fabrication of dicalcium Phosphate dihydrate-coated β-TCP granules and evaluation of their osteoconductivity using experimental rats
    Materials Science and Engineering: C, 2017
    Co-Authors: Khairul Anuar Shariff, Kanji Tsuru, Kunio Ishikawa
    Abstract:

    Abstract β-Tricalcium Phosphate (β-TCP) has attracted much attention as an artificial bone substitute owing to its biocompatibility and osteoconductivity. In this study, osteoconductivity of β-TCP bone substitute was enhanced without using growth factors or cells. Dicalcium Phosphate dihydrate (DCPD), which is known to possess the highest solubility among calcium Phosphates, was coated on β-TCP granules by exposing their surface with acidic calcium Phosphate Solution. The amount of coated DCPD was regulated by changing the reaction time between β-TCP granules and acidic calcium Phosphate Solution. Histomorphometry analysis obtained from histological results revealed that the approximately 10 mol% DCPD-coated β-TCP granules showed the largest new bone formation compared to DCPD-free β-TCP granules, approximately 2.5 mol% DCPD-coated β-TCP granules, or approximately 27 mol% DCPD-coated β-TCP granules after 2 and 4 weeks of implantation. Based on this finding, we demonstrate that the osteoconductivity of β-TCP granules could be improved by coating their surface with an appropriate amount of DCPD.

  • Regulation of DCPD formation on β-TCP granular surface by exposing different concentration of acidic calcium Phosphate Solution
    Key Engineering Materials, 2016
    Co-Authors: Khairul Anuar Shariff, Kanji Tsuru, Kunio Ishikawa
    Abstract:

    Regulation of DCPD formation on β-TCP granules was achieved by exposing β-TCP granular with different concentration of acidic calcium Phosphate Solution. It was found that a higher amount of DCPD was formed when exposed β-TCP granular with the higher concentration of acidic calcium Phosphate Solution. Morphological observation shows that the surface of β-TCP granular was fully coated with DCPD crystals after exposed with the higher concentration of acidic calcium Phosphate Solution. These results demonstrated that the DCPD formation on the β-TCP granular surface could be regulated by varying the concentration of acidic calcium Phosphate Solution.

  • Setting reaction of α-TCP spheres and an acidic calcium Phosphate Solution for the fabrication of fully interconnected macroporous calcium Phosphate
    Ceramics International, 2015
    Co-Authors: Pham Trung Kien, Kunio Ishikawa, Kanji Tsuru
    Abstract:

    Abstract Interconnected macroporous calcium Phosphate has attracted attention as an artificial bone substitute as well as a scaffold for tissue engineering. In this investigation, a setting reaction between α-tricalcium Phosphate (α-TCP) spheres and an acidic calcium Phosphate Solution (0.2 mol/L monocalcium Phosphate monohydrate – 0.1 mol/L phosphoric acid) was studied to assess the feasibility of fabricating fully interconnected macroporous calcium Phosphate. When 1.3 mm-diameter α-TCP spheres were exposed to an acidic calcium Phosphate Solution, brushite (dicalcium Phosphate dihydrate) was formed on the surface of the α-TCP spheres. The precipitated brushite crystals interlocked with one another and bridged the α-TCP spheres, resulting in a 10 min setting reaction at 37 °C that produced fully interconnected macroporous calcium Phosphate. The resultant calcium Phosphate macroporous structure had a porosity of 49.7±2.5% and an average pore size of 312±160 μm.

Régine Basséguy - One of the best experts on this subject based on the ideXlab platform.

  • Geobacter sulfurreducens: An iron reducing bacterium that can protect carbon steel against corrosion?
    Corrosion Science, 2015
    Co-Authors: Claudia Cote, Omar Rosas, Régine Basséguy
    Abstract:

    The effect of Geobacter sulfurreducens on the electrochemical behaviour of carbon steel in anaerobic Phosphate Solution is studied here. In natural environments, G. sulfurreducens is able to reduce Fe(III) to Fe(II) during the oxidation of acetate. High availability of Fe(II) promoted the formation of an iron (II) Phosphate layer on the steel. It is assumed that this Phosphate layer, formed only when bacteria were present, is responsible for maintaining the corrosion potential stable even after intrusion of air. In contrast, the corrosion potential in the abiotic experiments suffered an increase of 450 mV after few hours of exposure to air.

  • Geobacter sulfurreducens: an iron reducing bacterium that can protect carbon steel against corrosion ?
    Corrosion Science, 2015
    Co-Authors: Claudia Cote, Omar Rosas, Régine Basséguy
    Abstract:

    The effect of Geobacter sulfurreducens on the electrochemical behaviour of carbon steel in anaerobic Phosphate Solution is studied here. In natural environments, G. sulfurreducens is able to reduce Fe(III) to Fe(II) during the oxidation of acetate. High availability of Fe(II) promoted the formation of an iron (II) Phosphate layer on the steel. It is assumed that this Phosphate layer, formed only when bacteria were present, is responsible for maintaining the corrosion potential stable even after intrusion of air. In contrast, the corrosion potential in the abiotic experiments suffered an increase of 450 mV after few hours of exposure to air.

  • Hydrogen production by electrolysis of a Phosphate Solution on a stainless steel cathode
    International Journal of Hydrogen Energy, 2010
    Co-Authors: Leonardo De Silva Munoz, Alain Bergel, Damien Feron, Régine Basséguy
    Abstract:

    Abstract The catalytic properties of Phosphate species, already shown on the reduction reaction in anaerobic corrosion of steels, are exploited here for hydrogen production. Phosphate species work as a homogeneous catalyst that enhances the cathodic current at mild pH values. A voltammetric study of the hydrogen evolution reaction is performed using Phosphate Solutions at different concentrations on 316L stainless steel and platinum rotating disk electrodes. Then, hydrogen is produced in an electrolytic cell using a Phosphate Solution as the catholyte. Results show that 316L stainless steel electrodes have a stable behaviour as cathodes in the electrolysis of Phosphate Solutions. Phosphate (1 M, pH 4.0/5.0) as the catholyte can equal the performance of a KOH 25%w Solution with the advantage of working at mild pH values. The use of Phosphate and other weak acids as catalysts of the hydrogen evolution reaction could be a promising technology in the development of electrolysis units that work at mild pH values with low-cost electrodes and construction materials.

Kanji Tsuru - One of the best experts on this subject based on the ideXlab platform.

  • “Fabrication of arbitrarily shaped carbonate apatite foam based on the interlocking process of dicalcium hydrogen Phosphate dihydrate”
    Journal of Materials Science: Materials in Medicine, 2017
    Co-Authors: Yuki Sugiura, Kanji Tsuru, Kunio Ishikawa
    Abstract:

    Carbonate apatite (CO_3Ap) foam with an interconnected porous structure is highly attractive as a scaffold for bone replacement. In this study, arbitrarily shaped CO_3Ap foam was formed from α-tricalcium Phosphate (α-TCP) foam granules via a two-step process involving treatment with acidic calcium Phosphate Solution followed by hydrothermal treatment with NaHCO_3. The treatment with acidic calcium Phosphate Solution, which is key to fabricating arbitrarily shaped CO_3Ap foam, enables dicalcium hydrogen Phosphate dihydrate (DCPD) crystals to form on the α-TCP foam granules. The generated DCPD crystals cause the α-TCP granules to interlock with each other, inducing an α-TCP/DCPD foam. The interlocking structure containing DCPD crystals can survive hydrothermal treatment with NaHCO_3. The arbitrarily shaped CO_3Ap foam was fabricated from the α-TCP/DCPD foam via hydrothermal treatment at 200 °C for 24 h in the presence of a large amount of NaHCO_3.

  • Effect of citric acid on setting reaction and tissue response to β-TCP granular cement.
    Biomedical materials (Bristol England), 2017
    Co-Authors: Naoyuki Fukuda, Kanji Tsuru, Yoshihide Mori, Kunio Ishikawa
    Abstract:

    We recently reported that when an acidic calcium Phosphate Solution is mixed with β-tricalcium Phosphate (β-TCP) granules, the resulting dicalcium Phosphate dihydrate (DCPD) crystals form bridges between the β-TCP granules, creating a set interconnected porous structure in approximately 1 min. Although this self-setting β-TCP granular cement (β-TCPGC) is useful for clinical applications, the short setting time is a key drawback for handling. In this study, the setting time of β-TCPGC was adjusted with the addition of citric acid, which is a known inhibiter of DCPD crystal growth. As the concentration of citric acid in the acidic calcium Phosphate Solution increased, the amount of DCPD formation in the set β-TCPGC decreased, and the crystal morphology of DCPD became elongated. β-TCPGC prepared with various citric acid concentrations were used as grafting material in rat calvarial bone defects to evaluate bone regeneration in vivo. Four weeks after implantation, no inflammatory reaction and approximately 20% new bone formation were observed, regardless of the presence or absence of citric acid in the liquid phase of β-TCPGC. We concluded, therefore, that citric acid might be a useful retarder of β-TCPGC setting times.

  • Fabrication of dicalcium Phosphate dihydrate-coated β-TCP granules and evaluation of their osteoconductivity using experimental rats
    Materials Science and Engineering: C, 2017
    Co-Authors: Khairul Anuar Shariff, Kanji Tsuru, Kunio Ishikawa
    Abstract:

    Abstract β-Tricalcium Phosphate (β-TCP) has attracted much attention as an artificial bone substitute owing to its biocompatibility and osteoconductivity. In this study, osteoconductivity of β-TCP bone substitute was enhanced without using growth factors or cells. Dicalcium Phosphate dihydrate (DCPD), which is known to possess the highest solubility among calcium Phosphates, was coated on β-TCP granules by exposing their surface with acidic calcium Phosphate Solution. The amount of coated DCPD was regulated by changing the reaction time between β-TCP granules and acidic calcium Phosphate Solution. Histomorphometry analysis obtained from histological results revealed that the approximately 10 mol% DCPD-coated β-TCP granules showed the largest new bone formation compared to DCPD-free β-TCP granules, approximately 2.5 mol% DCPD-coated β-TCP granules, or approximately 27 mol% DCPD-coated β-TCP granules after 2 and 4 weeks of implantation. Based on this finding, we demonstrate that the osteoconductivity of β-TCP granules could be improved by coating their surface with an appropriate amount of DCPD.

  • Regulation of DCPD formation on β-TCP granular surface by exposing different concentration of acidic calcium Phosphate Solution
    Key Engineering Materials, 2016
    Co-Authors: Khairul Anuar Shariff, Kanji Tsuru, Kunio Ishikawa
    Abstract:

    Regulation of DCPD formation on β-TCP granules was achieved by exposing β-TCP granular with different concentration of acidic calcium Phosphate Solution. It was found that a higher amount of DCPD was formed when exposed β-TCP granular with the higher concentration of acidic calcium Phosphate Solution. Morphological observation shows that the surface of β-TCP granular was fully coated with DCPD crystals after exposed with the higher concentration of acidic calcium Phosphate Solution. These results demonstrated that the DCPD formation on the β-TCP granular surface could be regulated by varying the concentration of acidic calcium Phosphate Solution.

  • Setting reaction of α-TCP spheres and an acidic calcium Phosphate Solution for the fabrication of fully interconnected macroporous calcium Phosphate
    Ceramics International, 2015
    Co-Authors: Pham Trung Kien, Kunio Ishikawa, Kanji Tsuru
    Abstract:

    Abstract Interconnected macroporous calcium Phosphate has attracted attention as an artificial bone substitute as well as a scaffold for tissue engineering. In this investigation, a setting reaction between α-tricalcium Phosphate (α-TCP) spheres and an acidic calcium Phosphate Solution (0.2 mol/L monocalcium Phosphate monohydrate – 0.1 mol/L phosphoric acid) was studied to assess the feasibility of fabricating fully interconnected macroporous calcium Phosphate. When 1.3 mm-diameter α-TCP spheres were exposed to an acidic calcium Phosphate Solution, brushite (dicalcium Phosphate dihydrate) was formed on the surface of the α-TCP spheres. The precipitated brushite crystals interlocked with one another and bridged the α-TCP spheres, resulting in a 10 min setting reaction at 37 °C that produced fully interconnected macroporous calcium Phosphate. The resultant calcium Phosphate macroporous structure had a porosity of 49.7±2.5% and an average pore size of 312±160 μm.

Isei Nakamura - One of the best experts on this subject based on the ideXlab platform.

A Shimada - One of the best experts on this subject based on the ideXlab platform.