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113 results on '"Konishi Toshiisa"'

22. Solid-state nuclear magnetic resonance study of setting mechanism of beta-tricalcium phosphate-inositol phosphate composite cements

Author

Konishi, Toshiisa, Yamashita, Kohei, Nagata, Kohei, Lim, Poon Nian, Thian, Eng San, and Aizawa, Mamoru

Subjects
setting mechanism, inositol phosphate, solid-state NMR, calcium-phosphate cement, beta-tricalcium phosphate
Abstract

Solid-state nuclear magnetic resonance (NMR) spectroscopy is a technique, which can be used to provide insight into the chemical structure of non-crystalline and crystalline materials. Hence, the present study aimed to elucidate the setting mechanism of CPC, which was fabricated using beta -tricalcium phosphate (beta -TCP)-inositol phosphate (IP6) composite powder using NMR In addition, the effect of IP6 on the local chemical structure of the beta -TCP-IP6 composite powder and its hardened cement would also be investigated. The H-1 -> P-31 heteronuclear correlation NMR spectrum revealed that an amorphous hydrated layer, along with small amount of hydroxyapatite (HA) was formed on the surface of beta -TCP during the ball-milling process. Results demonstrated that the IP6 in the hydrated layer on the surface of beta -TCP inhibited the formation of HA. Moreover, the setting reaction of the cement was mainly triggered by the dissolution of the amorphous hydrated layer on beta -TCP surface, and subsequent precipitation, followed by the inter-entanglement between the HA crystals on the beta -TCP.

Published
2019

24. Anisotropic coating of a-plane oriented hydroxyapatite via a drop-on-demand micro-dispensing technique.

Author

Konishi, Toshiisa, Lye, Yun Min, Qiu, Xihe, Lim, Poon Nian, and Thian, Eng San

Subjects
*HYDROXYAPATITE, *SURFACE coatings, *BONES, *DENTAL enamel, *HEAT treatment, *HYDROXYAPATITE coating, *ORTHOTROPIC plates
Abstract

Bone and tooth enamel surface are made up of different crystallographically hydroxyapatite (HA), whereby bone comprises a(b)-planes of HA whilst tooth enamel comprises c-planes of HA. The reason behind the difference between HA orientations in both tissues are still yet to be discovered. We report the fabrication of anisotropic coatings of a-plane oriented HA according to the following process: (i) synthesis of a-plane oriented HA powders via a hydrothermal reaction and (ii) fabrication of a-plane oriented HA coatings via a Drop-on-Demand (DoD) micro-dispensing technique. Two types of HAs with high a-plane orientation degree of 72.2 and 75.6% (HA10 and HA84, respectively) was synthesised for the DoD coatings. The HA84 coating demonstrated more uniform and flatter surface than HA10 coating. The heat treatment of HA10 and HA84 coatings prepared with mesh-sieved particles led to a low adhesion strength for the substrates. However, the orientation degrees of those coatings (96.0 and 94.6%, respectively) were higher than the coatings without mesh-sieving. [ABSTRACT FROM AUTHOR]

Published
2020
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26. Preparation of chitosan-hydroxyapatite composite mono-fiber using coagulation method and their mechanical properties

Author

Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Graduate School of Natural Science and Technology, Okayama University, CEMUC, Departamento de Engenharia Metalúrgica e Materiais, Faculdade de Engenharia, Universidade do Porto, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology/ Frontier Research Academy for Young Researchers, Kyushu Institute of Technology, Okada, Takuma, Nobunaga, Yuta, Konishi, Toshiisa, Yoshioka, Tomohiko, Hayakawa, Satoshi, Lopes, Maria Ascensão, Miyazaki, Toshiki, Shirosaki, Yuki, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Graduate School of Natural Science and Technology, Okayama University, CEMUC, Departamento de Engenharia Metalúrgica e Materiais, Faculdade de Engenharia, Universidade do Porto, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology/ Frontier Research Academy for Young Researchers, Kyushu Institute of Technology, Okada, Takuma, Nobunaga, Yuta, Konishi, Toshiisa, Yoshioka, Tomohiko, Hayakawa, Satoshi, Lopes, Maria Ascensão, Miyazaki, Toshiki, and Shirosaki, Yuki

Abstract

type:Journal Article, Autograft has been carried out for anterior cruciate ligament (ACL) reconstruction surgery. However, it has negative aspect because patients lose their healthy ligaments from other part. We focus on a chitosan-hydroxyapatite (HAp) composite fiber as a scaffold of ligament regeneration. Chitosan- HAp composite fiber was made by using coagulation method. Chitosan-NaH2PO4 solution was coagulated with coagulation bath including calcium ion to get the mono-fiber and then treated with sodium hydroxide solution to form HAp in fiber matrix. The mechanical property of the fiber was improved by the stretching of the wet one because of the orientation of chitosan molecule and the interaction between chitosan and HAp. Maximum stress was improved with increasing of sodium dihydrogen phosphate until 0.03 M. The swelling ratio of the fiber was inhibited by composited with HAp. Additionally, bone-bonding ability was confirmed by SBF soaking tests., source:https://doi.org/10.1016/j.carbpol.2017.07.072

Published
2018

28. Preparation of chitosan-HAp composite fiber for artificial ligament

Author

Shirosaki Yuki, Hayakawa Satoshi, Konishi Toshiisa, Yoshioka Tomohiko, Nobunaga Yuta, Okada Takuma, and Miyazaki Toshiki

Subjects
Materials science, Histology, Composite number, Biomedical Engineering, Bioengineering, Chitosan, chemistry.chemical_compound, medicine.anatomical_structure, chemistry, Ligament, medicine, Fiber, Composite material, Biotechnology
Published
2016
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34. Effect of copper substitution on the local chemical structure and dissolution property of copper-doped β-tricalcium phosphate.

Author

Konishi, Toshiisa, Nagano, Yasuyuki, Maegawa, Marina, Lim, Poon Nian, and Thian, Eng San

Subjects
NUCLEAR magnetic resonance spectroscopy, CHEMICAL structure, NUCLEAR magnetic resonance, BIOMATERIALS, PHOSPHATES, CRYSTAL structure
Abstract

Substitution of inorganic ions into β-tricalcium phosphate (β-TCP) is a well-known approach for facilitating biological functions of bioceramics. However, the dissolution mechanism of those β-TCPs is still under intensive debates. In the present study, the effect of copper substitution into β-TCP crystal structure on the local chemical structure and dissolution property of the copper-doped β-TCP (CuTCP) was investigated to clarify the dissolution mechanism of β-TCP. A copper-dependent decrease in the dissolution rate of CuTCP with time was observed. The 1H → 31P nuclear magnetic resonance (NMR) spectra of 10 mol% copper-doped β-TCP after the dissolution test demonstrated an amorphous hydrated layer on the surface of β-TCP core particles, which contained hydroxyapatite and dicalcium phosphate dihydrate and anhydrate. As such, all the dissolution curves could be curve-fitted by a heterogeneous dissolution model composing of fast and slow dissolution components. Overall, dissolution mechanism could be proposed as follows: the CuTCP particles initially dissolved by hydrolysis based on the fast dissolution component. Subsequently, the amorphous hydrated layers were formed on their surface, and caused the diffusion-controlled dissolution. As the result, the slow dissolution component would be dominant, and led to the decreased dissolution rate. Understanding the dissolution mechanism of copper doped β-tricalcium phosphate (CuTCP) is crucial for designing an angiogenetic controlled copper release CuTCP for therapeutic biomaterials. However, dissolution mechanism of β-TCP or CuTCP is still under intensive debates. This study demonstrated for the first time, that amorphous hydrated layers were formed on the CuTCP particle surface during its dissolution process, which caused a diffusion-controlled dissolution, and decreased the dissolution rate of CuTCP. This work not only provided a novel dissolution mechanism of β-TCP or CuTCP, but also a new finding for designing an angiogenetic controlled copper release CuTCP for therapeutic biomaterials. [ABSTRACT FROM AUTHOR]

Published
2019
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38. Fabrication of chelate‐setting α‐tricalcium phosphate cement using sodium citrate and sodium alginate as mixing solution and its in vivo osteoconductivity.

Author

Konishi, Toshiisa, Lim, Poon Nian, Honda, Michiyo, Nagaya, Masaki, Nagashima, Hiroshi, Thian, Eng San, and Aizawa, Mamoru

Abstract

Abstract: Moldable and injectable calcium‐phosphate cements (CPCs) are material candidates for bone replacement applications. In the present study, we examined the effectiveness of sodium alginate and sodium citrate additives to the liquid phase of CPC, in improving its handling property as well as mechanical strength. The use of these additives enhanced the handling property significantly, in terms of consistency as compared to CPC without additives due to the liquefying effect caused by the adsorption of citrate ions on the cement particles. Sodium alginate and sodium citrate were added to CPC, which was set by the chelate‐bonding capability of inositol phosphate, and was composed of mainly α‐tricalcium phosphate (α‐TCP) phase (>90%). The compressive strength of the CPC containing sodium alginate and sodium citrate was 3.4 ± 0.3 MPa, which was significantly higher than cement without additives. Furthermore, this cement exhibited favorable osteoconductivity and bioresorbability, and remained the α‐TCP phase after 4‐week implantation in a pig tibiae model. These results suggested that the cement is a potential candidate as a bioresorbable paste‐like artificial bone. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2361–2370, 2018. [ABSTRACT FROM AUTHOR]

Published
2018
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41. Development of Bioresorbable Calcium-Phosphate Cements Hybridized with Gelatin Particles and their In Vivo Evaluation Using Pig’s Tibia Model

Author

Kiminami, Keishi, primary, Matsuoka, Kento, additional, Nagata, Kohei, additional, Konishi, Toshiisa, additional, Honda, Michiyo, additional, Hayashida, Gota, additional, Nakano, Kazuaki, additional, Nagaya, Masaki, additional, Arimura, Hidetoshi, additional, Nagashima, Hiroshi, additional, and Aizawa, Mamoru, additional

Published
2014
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49. Comparative Study on Bioresorbability of Chelate-Setting Cements with Various Calcium-Phosphate Phase Using Rabbit Model

Author

Konishi, Toshiisa, primary, Takahashi, Shuhei, additional, Mizumoto, Minori, additional, Honda, Michiyo, additional, Kida, Koki, additional, Horiguchi, Yukiko, additional, Oribe, Kazuya, additional, Ishii, Ken, additional, Morisue, Hikaru, additional, Toyama, Yoshiaki, additional, Matsumoto, Morio, additional, and Aizawa, Mamoru, additional

Published
2012
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