Long-term Conversion of 45S5 Bioactive Glass-ceramic Microspheres in Aqueous Phosphate Solution


Best, S. and Planell, J. A.


The conversion of 45S5 glass and glass-ceramics to a hydroxyapatite (HA)-like material in vitro has been studied extensively, but only for short reaction times (typically <3 months). In this paper, we report for the first time on the long-term conversion of 45S5 glass-ceramic microspheres (designated 45S5c) in an aqueous phosphate solution. Microspheres of 45S5c (75-150 μm) were immersed for 10 years at room temperature (~25 °C) in K2HPO4 solution with a concentration of 0.01 M or 1.0 M, and with a starting pH of 7.0 or 9.5. The reacted 45S5c microspheres and solutions were analyzed using structural and analytical techniques. Only 25-45 vol% of the 45S5c microspheres were converted to an HA-like material after the 10 year reaction. In solutions with a starting pH of 9.5, an increase in the K2HPO4 concentration from 0.01 to 1.0 M resulted in a doubling of the volume of the microspheres converted to an HA-like material but had little effect on the composition of the HA-like product. In comparison, reaction of the 45S5c microspheres in the solution with a starting pH of 7.0 resulted in an HA-like product in the 0.01 M K2HPO4 solution but a calcium pyrophosphate product, Ca10K4(P2O7)6.9H2O, in the 1.0 M solution. The consequences of these results for the long-term use of 45S5 glass-ceramics in biomedical applications are discussed.


Materials Science and Engineering

Keywords and Phrases

Characterization and Evaluation of Materials; Metallic Materials; Ceramics-Glass-Composites-Natural Methods; Polymer Sciences; Biomaterials; Surfaces and Interfaces

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Article - Journal

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© 2012 Springer Verlag, All rights reserved.

Publication Date

01 Jan 2012