Advanced solid-state 1H/31P NMR characterization of pyrophosphate-doped calcium phosphate cements for biomedical applications: The structural role of pyrophosphate. Issue 16 (November 2019)

• Record Type: Journal Article
• Authors: Yu, Yang; Guo, Hua; Pujari-Palmer, Michael; Stevensson, Baltzar; Grins, Jekabs; Engqvist, Håkan; Edén, Mattias
• Is Part Of: Ceramics international. Volume 45:Issue 16(2019)
• Page Start: 20642
• Page End: 20655
• Publication Date: 2019-11
• Subjects: Bioceramics -- Monetite cement -- DCPA -- Amorphous calcium pyrophosphate -- 31P NMR -- 1H NMR -- 2D homonuclear/heteronuclear correlation NMR spectroscopy -- Rietveld refinement -- Cement structure; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2019.07.047
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: From a suite of advanced magic-angle spinning (MAS) NMR spectroscopy and powder X-ray diffraction (PXRD) experiments, we present a comprehensive structural analysis of pyrophosphate-bearing calcium phosphate cements that are investigated for bone-inductive biomedical implants. The cements consist mainly of poorly ordered monetite (CaHPO4 ), along with minor Ca orthophosphate phases, and two distinct pyrophosphate constituents: crystalline β -Ca2 P2 O7 and amorphous calcium pyrophosphate (ACPP), the latter involving one water-bearing portion and another anhydrous component. Independent 2D MAS NMR experiments evidenced close contacts between the amorphous pyrophosphates and the monetite phase, where ACPP is proposed to form a thin layer coating the monetite particles. Heteronuclear 1 H– 31 P and homonuclear 31 P– 31 P correlation NMR experimentation enabled us to detect, identify, and quantify even minor cement constituents ( ≲ 2 mol%) that could not be ascertained by the Rietveld method. Quantitative phase analyses of the cements, as determined independently by 31 P NMR and PXRD, are contrasted and discussed.