Bioceramics 17

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Authors: Fukue Nagata, Tatsuya Miyajima, Kay Teraoka, Yoshiyuki Yokogawa
Abstract: Porous biodegradable microspheres were successfully obtained by an improvement single step and surfactant-free emulsion solvent evaporation method. The organic phase composed of PLA and dichloromethane was stirred in aqueous phase including Ca2+ ions to yield oil in water emulsion. During emulsification, stirring rate was increased so as to produce the W/O/W emulsion that results in microspheres with internal pores. The interface of internal water/oil was stable in W/O/W emulsion, which was explained that the bond between Ca2+ ions and carboxyl group of poly(lactic acid) would be stabilized the internal water/oil interface. Adding PO4 3- aqueous solution prompted to precipitate low crystallized hydroxyapatite on the external oil/water interface, and the precipitated hydroxyapatite would stabilizied microspheres formation. The resulting microspheres were approximately 100-500 µm with internal spherical pores of 10-200 µm in diameter. The porous biodegradable microspheres were expected to be utilized as injectable bone substitutes that allow bone ingrowth and bone regeneration.
819
Authors: Kanji Tsuru, Yuki Shirosaki, Satoshi Hayakawa, Akiyoshi Osaka, M.A. Lopes, José D. Santos, Maria Helena F.V. Fernandes
Abstract: Chitosan-silicate hybrid membranes were prepared using g-glycidoxy-propyltrimethoxysilane (GPSM) through a sol-gel process. The amino groups of chitosan chains were reacted with the epoxy groups of GPSM and GPSM have a function as the agent to cross-link the chitosan chains. The cross-linking degree of the hybrid membranes was determined by ninhydrin assay. Fourier-transform infrared (FT-IR) spectroscopy and 29Si cross-polarization (CP) magic-angle spinning (MAS)-NMR spectroscopy were used to assess the structure of the hybrid membranes. The biodegradability of the hybrid membranes in phosphate-buffered saline solution or lysozyme solution was investigated as a function of the GPSM concentration.
823
Authors: D.H. Kim, Se Ho Lee, Kyoung Nam Kim, Kwang Mahn Kim, I.B. Shim, Yong Keun Lee
Abstract: Ceramic ferrites can be used to cancer-treatment. Heating of certain organs or tissue up to temperature between 42oC and 45oC preferentially for cancer therapy is called hyperthermia. We synthesized ferrites with various compositions in the system Co1-xNixFe2O4 as hyperthermic thermoseed in cancer-treatment and evaluated their effects on the necrosis of cancer cells under alternating magnetic field in vivo as well as in vitro. When a CoFe2O4 was placed into 0.2 ml distilled water, the greatest temperature change in this study, Δ T=29.3oC, was observed. More than half of the carcinoma cells were dead after exposure to alternating magnetic field using CoFe2O4, while normal cells were survived more than 60%. The injection of this ferrite particles into the tumor bearing mice was able to suppress the number and volume of tumors. CoFe2O4 is expected the useful hyperthermic thermoseed in cancer-treatment because it exhibited the greatest necrosis of carcinoma cells in vitro and in vivo.
827
Authors: Niklas Axén, Hakan Engqvist, Jesper Lööf, Peter Thomsen, Leif Hermansson
831
Authors: I.A. Key, S. Pina, Simeon Agathopoulos, D.U. Tulyaganov, José Maria F. Ferreira
Abstract: In the framework of producing new composite biomaterials, this study investigated the interfacial interactions between molten brand new biocompatible glasses with model formulations and Ti, hydroxyapatite, zirconia and a CrNi-steel. Analysis, by grouping the results of each particular substrate, indicates that Ti reduces the molten glass-oxides, HA tends to diffuse with them, zirconia grain-boundaries are vulnerable towards them, and Cr-Ni-steel very poorly adhere to them. Analysis, by grouping the results of each particular glass, indicates that the matching of their expansion coefficient with that of substrate and crystallization affect the formation of continuous or cracked interface. Viscosity and surface tension of glasses determine wettability. Wettability is not however determinative index of evaluating the quality and the strength of the resulting interfaces.
835
Authors: Xiao Yan Lin, Xu Dong Li, Hong Song Fan, Yu Mei Xiao, Jian Lu, Xing Dong Zhang
Abstract: Hydroxyapatite/collagen (HA/COL) composites were prepared using coprecipitation and in-situ synthesis methods. All these processes yielded nanosize poorly crystallized hydroxyapatite/collagen composites. The low temperature in situ formed composites showed some features of natural bone in phase composition, crystal size and crystallinity. Compare with the composite prepared by coprecipitation synthesis, the composite resulted from a low temperature in situ synthesis method showed better homogeneity and mechanical properties. It is confirmed that the low temperature in situ synthesis method was an effective way to obtain biomimetic nanoHA/COL composites with good homogeneity and mechanical properties.
839
Authors: Akira Watazu, H. Oguchi, T. Yamada, Tsutomu Sonoda, Kiyotaka Katou, Toru Nonami, Naobumi Saito
Abstract: On the hydroxyapatite/titanium alloy composite disks, the normal human osteoblast cells were cultured. As a result, the samples were covered with normal human osteoblast cells after 2 hours. Moreover, we did not observe cracks in any of the HA granules, and the normal human osteoblast cells extended between the HA granules and the titanium alloy. From these results, we have concluded that this material has good biocompatibility.
843
Authors: H.W. Lee, S.U. Im, S.E. Song, C.S. Kim, Se Young Choi, Yong Keun Lee, Kyoung Nam Kim, Chong Kwan Kim, Seong Ho Choi
Abstract: This study evaluated periodontal repair and biomaterial reaction following implantation of a newly fabricated calcium aluminate bony cement incorporating LiF-maleic acid on the regeneration of 1-wall intrabony defects in the beagle dogs. The surgical control group received a flap operation only, while the experimental group was treated with calcium aluminate bony cement incorporating LiF-maleic acid. The subjects were sacrificed 12 weeks after surgery and a comparative histologic analysis was done. In the experimental group, the grafted calcium aluminate cement was not absorbed and fibrous connective tissue was epithelized around the particles of the grafted bony cement. Because of certain favorable properties, such as its easy manipulation and its ability to maintain the morphology of the defect site by acting as a scaffold, the newly developed cement is suitable for us as a graft material, and could be used very effectively in alveolar augmentation. However, further study needs to be conducted before it can be used as a bone graft material for periodontal tissue regeneration.
847
Authors: D.H. Min, M.J. Kim, J.H. Yun, C.S. Kim, Yong Keun Lee, Seong Ho Choi, Kyoung Nam Kim, Chong Kwan Kim
Abstract: This study evaluated periodontal repair and biomaterial reaction following implantation of a newly fabricated calcium phosphate block bone with chitosan membrane on the regeneration of 1-wall intrabony defects in the beagle dogs. The surgical control group received a flap operation only, while the experimental group I was treated with a chitosan nonwoven membrane only and the experimental group II was treated with a chitosan nonwoven membrane and a calcium phosphate block bone. The subjects were sacrificed 12 weeks after surgery and a comparative histometric analysis was done. No root resorption or ankylosis were observed in the experimental group. Mann-Whitney U test showed that the experimental group II produced statistically significant higher gain in connective tissue adhesion, new cementum regeneration and new bone formation. Based on histological results, the calcium phosphate block bone successfully functioned as a osteoconductive scaffold for invading cells of host.
851
Authors: Akihiko Yoshida, Toshiki Miyazaki, Eiichi Ishida, Masahiro Ashizuka
Abstract: Organic-inorganic composites composed of organic polymer and carbonate hydroxyapatite (CHAp) would be useful bone substitute materials exhibiting low young’s modulus and bone-bonding bioactivity. In this work, such a composite was synthesized from cellulose (CEL)and CHAp through mechanochemical reaction. Homogeneous bulk CEL-CHAp composites were obtained when poly( ε-caprolactone) (PCL) was added as plasticizer with PCL/(PCL+CEL) weight ratio of 20 wt% or less. The CEL-CHAp composites contained B-type CHAp in inorganic phase. The composites with (CEL+PCL)/(CHAp) weight ratio = 20/80 and 10/90 kept the shape in simulated body fluid (SBF), and showed apatite formation after soaking in SBF. Therefore, the CEL-CHAp composites are expected to be materials with low young’s modulus and bioactivity.
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