An investigation of bioactive glass powders by sol‐gel processing

TLDR

Bioactive glass powders composed of SiO₂–CaO–P₂O₅ can be synthesized at lower temperatures via sol‑gel processing, yet conventional methods produce powders that form no interfacial bond upon implantation, a bonding that depends on surface hydroxyapatite formation. The study investigated how varying SiO₂ content in sol‑gel derived powders affects hydroxyapatite layer formation in Tris‑buffered solution. Hydroxyapatite formation was monitored by FT‑IRRS, while X‑ray diffraction and BET analyses characterized the powders’ chemical and physical properties. The rate of hydroxyapatite formation decreased with increasing SiO₂ content below 90 mol %, no film formed above 90 mol %, and the bioactivity limit for sol‑gel powders (90 mol %) was higher than that of conventionally melted powders (60 mol %), demonstrating that microstructural control via sol‑gel processing can significantly broaden the bioactive composition range.

Abstract

Abstract Bioactive glass powders, with a composition of SiO 2 ‐CaO‐P 2 O 5 ,have been successfully synthesized via a sol‐gel process at considerably loer temperatures than required for conventional melting method. Bioactive glass powders made via conventional methods form an interfacial bond wih none when they are implanted. Bonding is correlated with the formation of a surface hydroxyapatite layer. This study examinded the formation of a hydroxyapatite layer in Tris‐buffered solution as a function of SiO 2 content of sol‐gel derived powders. A FT‐IRRS technique was used to monitor the formation of the hydroxyapatite on the surface of the powders. X‐ray diffraction analysis and BET were also used to characterize the chemical and physical properties of the sol‐gel derived bioactive powders. It was discovered that: (a) the rate of hydroxyapatite formation decreased wih increasing SiO 2 content for powders whose SiO 2 content was less than 90 mol%; (b) a hydroxyapatite film does not form for the powders whose SiO 2 content is more than 90 mol%; (c) the SiO 2 limit, beyond which the powders lost their bioactivity, was much higher for bioactive glass powders mad through sol‐gel process (90%) than those made by conventional melting methods (60%). These results indicate that it is possible to significantly expand the bioactive composition range through microstructural control made possible by sol‐gel processing techniques.