Development of PMMA bone cement loaded with a ferrimagnetic bioactive glass ceramic for hypethermia treatment

INTRODUCTION The design of a composite material like Polymethylmethacrylate bone cement loaded with a bioactive and ferrimagnetic glass-ceramic is very useful against the development and proliferation of bone tumors. The biomaterial can be used in hyperthermia treatment that produces heat by hysteresis loss due to magnetic phase of the glass-ceramic[1]. The aim of the present work is the synthesis and characterization of a composite material in which the disperse phase is a glass ceramic (SC45) with magnetic property, embedded polymeric bone cement. EXPERIMENTAL METHODS The SC45 powders,(see [1] for the chemical composition) sieved below 20 micron, were mixed in different amounts (10, 15, 20% wt) with the polymeric solid phase of a commercial bone cement (Palamed®MV). The mixed powders and the liquid monomer of the bone cements were mixed manually for two minutes and after that put inside a mold, obtaining the composite cements. P10, P15, P20 and plain cement (as control) samples have been prepared. The characterizations were developed for all formulations proposed as described below. Mechanical testing of cement samples The compressive strength of the cement were evaluated according to standard ISO 5833 procedure. For each formulation 6 samples were tested. Calorimetric measurements The heat generation was measured with induction furnace at fixed frequency and alternate electromagnetic field. The samples were placed in a test tube with 10 ml of distilled water. The increase of temperature that occurred following the heat transfer from the magnetic phase of the composite to water, was measured with a thermocouple. SEM and EDS analysis before and after bioactivity test Scanning electron microscopy had been implemented to analyze the morphology and composition of the samples. RESULTS AND DISCUSSION The compression strength of the composites depends from the amount of glass-ceramic phase; nevertheless the reached values satisfy the ISO requirements ( >70 MPa). Calorimetric tests show an maximum increasing temperature of 40°C that respect the limit imposed by hyperthermia therapy. By soaking of the samples in SBF for 28 day the growth of hydroxyapatite was observed. CONCLUSION The preliminary experimental tests demonstrated a good mechanical properties and a good osteointegration. The calorimetric test evidenced a range of temperature adapted to biological environment. REFERENCES 1. O. Bretcanu et al. Journal of Magnetism and Magnetic Materials, 305 (2006) 529-533. ACKNOWLEDGMENTS The authors would like to thank to the MIUR Grant for Young researchers.