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Title: Enhanced stability and local structure in biologically relevant amorphous materials containing pyrophosphate

Abstract

There is increasing evidence that amorphous inorganic materials play a key role in biomineralisation in many organisms, however the inherent instability of synthetic analogues in the absence of the complex in vivo matrix limits their study and clinical exploitation. To address this, we report here an approach that enhances long-term stability to >1 year of biologically relevant amorphous metal phosphates, in the absence of any complex stabilizers, by utilizing pyrophosphates (P{sub 2}O{sub 7}{sup 4-}); species themselves ubiquitous in vivo. Ambient temperature precipitation reactions were employed to synthesise amorphous Ca{sub 2}P{sub 2}O{sub 7}.nH{sub 2}O and Sr{sub 2}P{sub 2}O{sub 7}.nH{sub 2}O (3.8 < n < 4.2) and their stability and structure were investigated. Pair distribution functions (PDF) derived from synchrotron X-ray data indicated a lack of structural order beyond 8 {angstrom} in both phases, with this local order found to resemble crystalline analogues. Further studies, including {sup 1}H and {sup 31}P solid state NMR, suggest the unusually high stability of these purely inorganic amorphous phases is partly due to disorder in the P-O-P bond angles within the P{sub 2}O{sub 7} units, which impede crystallization, and to water molecules, which are involved in H-bonds of various strengths within the structures and hamper themore » formation of an ordered network. In situ high temperature powder X-ray diffraction data indicated that the amorphous nature of both phases surprisingly persisted to 450 C. Further NMR and TGA studies found that above ambient temperature some water molecules reacted with P{sub 2}O{sub 7} anions, leading to the hydrolysis of some P-O-P linkages and the formation of HPO{sub 4}{sup 2-} anions within the amorphous matrix. The latter anions then recombined into P{sub 2}O{sub 7} ions at higher temperatures prior to crystallization. Together, these findings provide important new materials with unexplored potential for enzyme-assisted resorption and establish factors crucial to isolate further stable amorphous inorganic materials.« less

Authors:
; ; ; ; ; ;  [1];  [2]
  1. (CNRS-UMR)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
FOREIGN
OSTI Identifier:
1043721
Resource Type:
Journal Article
Journal Name:
J. Mater. Chem.
Additional Journal Information:
Journal Volume: 21; Journal Issue: (46) ; 2011; Journal ID: ISSN 0959-9428
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; AMBIENT TEMPERATURE; AMORPHOUS STATE; ANIONS; BOND ANGLE; CRYSTALLIZATION; DISTRIBUTION FUNCTIONS; HYDROLYSIS; IN VIVO; INSTABILITY; PHOSPHATES; PRECIPITATION; PYROPHOSPHATES; STABILITY; SYNCHROTRONS; WATER; X-RAY DIFFRACTION

Citation Formats

Slater, Colin, Laurencin, Danielle, Burnell, Victoria, Smith, Mark E., Grover, Liam M., Hriljac, Joseph A., Wright, Adrian J., and Birmingham UK). Enhanced stability and local structure in biologically relevant amorphous materials containing pyrophosphate. United States: N. p., 2012. Web. doi:10.1039/C1JM13930D.
Slater, Colin, Laurencin, Danielle, Burnell, Victoria, Smith, Mark E., Grover, Liam M., Hriljac, Joseph A., Wright, Adrian J., & Birmingham UK). Enhanced stability and local structure in biologically relevant amorphous materials containing pyrophosphate. United States. doi:10.1039/C1JM13930D.
Slater, Colin, Laurencin, Danielle, Burnell, Victoria, Smith, Mark E., Grover, Liam M., Hriljac, Joseph A., Wright, Adrian J., and Birmingham UK). Thu . "Enhanced stability and local structure in biologically relevant amorphous materials containing pyrophosphate". United States. doi:10.1039/C1JM13930D.
@article{osti_1043721,
title = {Enhanced stability and local structure in biologically relevant amorphous materials containing pyrophosphate},
author = {Slater, Colin and Laurencin, Danielle and Burnell, Victoria and Smith, Mark E. and Grover, Liam M. and Hriljac, Joseph A. and Wright, Adrian J. and Birmingham UK)},
abstractNote = {There is increasing evidence that amorphous inorganic materials play a key role in biomineralisation in many organisms, however the inherent instability of synthetic analogues in the absence of the complex in vivo matrix limits their study and clinical exploitation. To address this, we report here an approach that enhances long-term stability to >1 year of biologically relevant amorphous metal phosphates, in the absence of any complex stabilizers, by utilizing pyrophosphates (P{sub 2}O{sub 7}{sup 4-}); species themselves ubiquitous in vivo. Ambient temperature precipitation reactions were employed to synthesise amorphous Ca{sub 2}P{sub 2}O{sub 7}.nH{sub 2}O and Sr{sub 2}P{sub 2}O{sub 7}.nH{sub 2}O (3.8 < n < 4.2) and their stability and structure were investigated. Pair distribution functions (PDF) derived from synchrotron X-ray data indicated a lack of structural order beyond 8 {angstrom} in both phases, with this local order found to resemble crystalline analogues. Further studies, including {sup 1}H and {sup 31}P solid state NMR, suggest the unusually high stability of these purely inorganic amorphous phases is partly due to disorder in the P-O-P bond angles within the P{sub 2}O{sub 7} units, which impede crystallization, and to water molecules, which are involved in H-bonds of various strengths within the structures and hamper the formation of an ordered network. In situ high temperature powder X-ray diffraction data indicated that the amorphous nature of both phases surprisingly persisted to 450 C. Further NMR and TGA studies found that above ambient temperature some water molecules reacted with P{sub 2}O{sub 7} anions, leading to the hydrolysis of some P-O-P linkages and the formation of HPO{sub 4}{sup 2-} anions within the amorphous matrix. The latter anions then recombined into P{sub 2}O{sub 7} ions at higher temperatures prior to crystallization. Together, these findings provide important new materials with unexplored potential for enzyme-assisted resorption and establish factors crucial to isolate further stable amorphous inorganic materials.},
doi = {10.1039/C1JM13930D},
journal = {J. Mater. Chem.},
issn = {0959-9428},
number = (46) ; 2011,
volume = 21,
place = {United States},
year = {2012},
month = {10}
}