TY - JOUR A1 - Hayakawa, S. A1 - Sakai, A. A1 - Tsuru, K. A1 - Osaka, A. A1 - Fujii, E. A1 - Kawabata, K. A1 - Jäger, Christian T1 - Preparation and Characterization of Boron-containing Hydroxyapatite N2 - Boron-containing hydroxyapatite (BHAp) particles were synthesized by the wet chemical processing method and subsequent thermal treatment at the temperature ranging from 700-1200°C, and examined the effect of boron introduction on the microstructure of BHAp. The local structure around boron and phosphorus in the BHAp was analyzed by solid-state magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The heat-treatment above 700°C induced the thermal decomposition of HAp to β-TCP and then the chemical reaction between HAp and B(OH)3 was induced above 900°C, resulting in the formation of boron-substituted HAp particles accompanied by the formation of β-TCP and its transformation to α-TCP above 1200°C. KW - Hydroxyapatite KW - Boron KW - Structure KW - NMR KW - Thermal treatment PY - 2008 SN - 1013-9826 VL - 361-363 SP - 191 EP - 194 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-17584 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hayakawa, S. A1 - Kanaya, T. A1 - Tsuru, K. A1 - Shirosaki, Y. A1 - Osaka, A. A1 - Fujii, E. A1 - Kawabata, K. A1 - Gasqueres, G. A1 - Bonhomme, C. A1 - Babonneau, F. A1 - Jäger, Christian A1 - Kleebe, H.-J. T1 - Heterogeneous structure and in vitro degradation behavior of wet-chemically derived nanocrystalline silicon-containing hydroxyapatite particles N2 - 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 29Si NMR analysis revealed that the Si(IV) was incorporated in the HAp lattice in the form of Q0 (SiO4-4 or HSiO3-4) species, accompanied by the formation of condensed silicate units outside the HAp lattice structure, where the fraction and amount of Q0 species in the HAp lattice depends on the Si content. The 31P and 1H 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 Q0 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. KW - Silicate KW - Calcium phosphate KW - Hydroxyapatite KW - Degradation KW - Apatite formation PY - 2013 DO - https://doi.org/10.1016/j.actbio.2012.08.024 SN - 1742-7061 VL - 9 IS - 1 SP - 4856 EP - 4867 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-27319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -