ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

In vitro bioactivity and crystallization behavior of bioactive glass in the system SiO₂-CaO-Al₂O₃-P₂O₅-Na₂O-MgO-CaF₂

Melek Erol

Department of Chemical Engineering, Chemical & Metallurgical Engineering Faculty, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey

E-mail: erolm@itu.edu.tr

Received: 25 September 2009  Revised: 9 December 2009  Accepted: 17 December 2009

Abstract: In this study, bioactivity of glass in the system SiO₂-CaO-Al₂O₃-P₂O₅-Na₂O-MgO-CaF₂ was investigated. For this purpose, a glass sample was prepared by the traditional melting method. Crystallization behavior of bioactive glass was also investigated using differential thermal analyses. The Avrami constant of bioactive glass sample calculated according to the Ozawa equation was 3.72 ± 0.4, which indicates bulk crystallization. Using the Matusita-Sakka and the Kissinger equations, activation energy of crystal growth was determined as (394 ± 17) kJ mol⁻¹ and (373 ± 12) kJ mol⁻¹, respectively. These results indicate that the crystallization activation energy data of bioactive glass obtained in this study are accurate and reliable. Bioactivity of the resultant glass sample was analyzed by immersion in simulated body fluid. Scanning electron microscopy, thin film X-ray diffraction, ultraviolet spectroscopy and inductively coupled plasma techniques were used to monitor changes in the glass surface and the simulated body fluid composition. The results revealed that a hydroxyapatite layer was formed on the glass surface after 21 days of immersion in SBF. Formation of the hydroxyapatite layer confirmed the bioactivity of the glass in the system SiO₂-CaO-Al₂O₃-P₂O₅-Na₂O-MgO-CaF₂. In addition, physical and mechanical properties of the sample were measured to determine changes in the properties with the immersion time. The results show that bioactive glass maintained its strength during the immersion in a simulated body fluid solution.

Keywords: bioactive glass - crystallization kinetics - bioactivity - hardness - porosity

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-010-0028-4

Chemical Papers 64 (4) 482–490 (2010)