Solid-State 31P and 1H NMR Investigations of Amorphous and Crystalline Calcium Phosphates Grown Biomimetically From a Mesoporous Bioactive Glass

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• 作者：Renny Mathew ; Philips N. Gunawidjaja ; Isabel Izquierdo-Barba ; Kjell Jansson ; Ana Garc铆a ; Daniel Arcos ; Mar铆a Vallet-Reg铆 ; Mattias Ed茅n
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：October 27, 2011
• 年：2011
• 卷：115
• 期：42
• 页码：20572-20582
• 全文大小：1133K
• 年卷期：v.115,no.42(October 27, 2011)
• ISSN：1932-7455

文摘

By exploiting ¹H and ³¹P magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy, we explore the proton and orthophosphate environments in biomimetic amorphous calcium phosphate (ACP) and hydroxy-apatite (HA), as grown in vitro at the surface of a 10CaO鈥?5SiO₂鈥?P₂O₅ mesoporous bioactive glass (MBG) in either a simulated body fluid or buffered water. Transmission electron microscopy confirmed the presence of a calcium phosphate layer comprising nanocrystalline HA. Two-dimensional ¹H鈥?sup>31P heteronuclear correlation NMR established predominantly ¹H₂O鈫?sup>31PO₄^{3鈥?/sup> and O1H鈫?sup>31}PO₄^{3鈥?/sup> contacts in the amorphous and crystalline component, respectively, of the MBG surface-layer; these two pairs exhibit distinctly different 1H鈫?sup>31}P cross-polarization dynamics, revealing a twice as large squared effective ¹H鈥?sup>31P dipolar coupling constant in ACP compared with HA. These respective observations are mirrored in synthetic (well-crystalline) HA, and the amorphous calcium orthophosphate (CaP) clusters that are present in the pristine MBG pore walls: besides highlighting very similar local ¹H and ³¹P environments in synthetic and biomimetic HA, our findings evidence closely related NMR characteristics, and thereby similar local structures, of the CaP clusters in the pristine MBG relative to biomimetic ACP.