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Structural studies of bioactivity in sol–gel‐derived glasses by X‐ray spectroscopy
Author(s) -
Skipper Laura J.,
Sowrey Frank E.,
Pickup David M.,
Fitzgerald Victoria,
Rashid Rumana,
Drake Kieran O.,
Lin Zhongjie,
Saravanapavan Priya,
Hench Larry L.,
Smith Mark E.,
Newport Robert J.
Publication year - 2004
Publication title -
journal of biomedical materials research part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.849
H-Index - 150
eISSN - 1552-4965
pISSN - 1549-3296
DOI - 10.1002/jbm.a.30093
Subject(s) - simulated body fluid , materials science , calcium , xanes , spectroscopy , calcium silicate , absorption spectroscopy , x ray absorption spectroscopy , absorption (acoustics) , fluorescence spectroscopy , analytical chemistry (journal) , silicate , extended x ray absorption fine structure , diffraction , crystallography , fluorescence , chemical engineering , chemistry , optics , scanning electron microscope , chromatography , composite material , metallurgy , physics , quantum mechanics , engineering
Abstract Extended X‐ray absorption fine structure spectroscopy and X‐ray absorption near edge structure, X‐ray fluorescence spectroscopy, and X‐ray powder diffraction have been used to study the local calcium environment in four sol–gel‐derived bioactive calcium silicate glasses of the general formula (CaO) x (SiO 2 ) 1−x . The formation of a hydroxyapatite layer on the composition with the highest bioactivity ( x = 0.3) with time has been studied, in an in vitro environment, by immersion in simulated body fluid (SBF) at 37°C. The calcium oxygen environment in the four compositions has been shown to be six‐coordinate in character. Both the extended X‐ray absorption fine structure spectroscopy and X‐ray absorption near edge structure show a gradual increase in coordination number and CaO bond distance with longer exposure to SBF. X‐ray fluorescence show that calcium is quickly lost from the samples on exposure to SBF and the calcium concentration then recovers with time. There is clear evidence that the recovery of calcium content is due to the formation of a CaO‐P 2 O 5 ‐rich layer. Annealing of samples at 650°C shows the presence of what, on the length scales probed by X‐ray diffraction, appears to be noncrystalline calcium phosphate after 1 h of exposure to an SBF solution, which becomes more crystalline on longer exposure. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 354–360, 2004