Effect of Simulated Body Fluid on the Microstructure of Ferrimagnetic Bioglass-Ceramics
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P3.7.1
Effect of Simulated Body Fluid on the Microstructure of Ferrimagnetic Bioglass-Ceramics N. I. Papanearchou1, Th. Leventouri1, A. C. Kis2, A. Hotiu1, and I. M. Anderson3 1 Physics
Department, Florida Atlantic University, Boca Raton, FL 33431 Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada 3 Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge TN 37830 U.S.A 2
ABSTRACT The effect of simulated body fluid (SBF) on the structure and microstructure of ferrimagnetic bioglass ceramics (FBC) was investigated in series of samples in the system of the oxides [0.45(CaO, P2O5) (0.52-x)SiO2 xFe2O3 0.03Na2O], with x = 0.05, 0.10, 0.15, 0.20. Physical properties of the materials were studied as a function of processing parameters and time of immersion in SBF by x-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS). The in vitro experiment showed that bioactivity of the FBC varies with the composition of the oxides, heat treatment, and time of exposure in SBF in a non-systematic way. A surface layer of Si, P, Ca partially covers the Fe, O dendrites, while formation and size of pores is determined by the specific processing parameters of the materials.
INTRODUCTION Ferrimagnetic bioglass-ceramics (FBC) are multiphase, biocompatible and bioactive materials that were introduced for hyperthermic treatment of bone cancer, and they are tested to be effective in curing animal bone cancer [1, 2]. They were synthesized by melting procedures of the original bioglass [3] with the addition of Fe2O3 in the system of the oxides [P2O5, CaO, SiO2]. Fe2O3 forms magnetite (Fe3O4) that generates heat by hysteretic loss when an A.C. magnetic field is applied. Bioactivity of the FBC is related to calcium phosphates and calcium silicates that in a physiological environment form hydroxyapatite [Ca5(PO4)3OH], which is the idealized formula for the multi-substituted, calcium deficient apatite mineral phase of the bone. Several research groups have tested in vitro and in vivo the bioactivity of magnetic, as well as non-magnetic materials in various glass-ceramic systems [4, 5]. Here we report on the effect of SBF on the crystal structure and microstructure properties of series of FBC that were prepared with a systematic variation of processing parameters such as composition of reacting oxides, heat treatment temperature and time of immersion in SBF.
EXPERIMENTAL/DISCUSSION Preparation of series of samples in the system of the oxides [0.45(CaO, P2O5) (0.52-x)SiO2 xFe2O3 0.03Na2O], with x = 0.05, 0.10, 0.15, 0.20, as well as magnetic and crystal structure studies, have been published elsewhere [6, 7].
P3.7.2
Simulated body fluid (SBF) was prepared by dissolving reagent grade chemicals NaCl, NaHCO3, KCl, K2HPO4.3H2O, MgCl2.6H2O, CaCl2, Na2SO4; the solution was buffered at pH 7.25 with 50 mM tris [(CH2OH)3CNH2] and 45 mM of hydrochloric acid at 37 oC (human body temperature). The ion concentrations in SBF are given in Table I along with the
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