UNSPECIFIED. (2004) Structural studies of bioactivity in sol-gel-derived glasses by X-ray spectroscopy. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A, 70A (2). pp. 354-360. ISSN 0021-9304

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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)(SiO2)(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 37degreesC. 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 Ca-0 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-P2O5-rich layer. Annealing of samples at 650degreesC 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. (D 2004 Wiley Periodicals, Inc.

Item Type:	Journal Article
Subjects:	R Medicine
Journal or Publication Title:	JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A
Publisher:	WILEY-LISS
ISSN:	0021-9304
Date:	1 August 2004
Volume:	70A
Number:	2
Number of Pages:	7
Page Range:	pp. 354-360
Identification Number:	10.1002/jbm.a.30093
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/8220

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