New PMMA bone cement added with ferrimagnetic bioactive glass for hyperthermia treatment

INTRODUCTION The design of a composite material like Polymethylmethacrylate (PMMA) bone cement loaded with a bioactive and ferrimagnetic glass-ceramic is very useful against the development and proliferation of bone tumors. This biomaterial produces heat by magnetic hysteresis loss due to presence of magnetite (Fe3O4) inside the glass-ceramic phase1 and so it can be used in hyperthermia treatment. Moreover, the bioactive component of the glass-ceramic confers osteointegration property at the material. The aim of the present work is the synthesis and characterization of a composite cement in which the disperse phase is a glass ceramic (SC45) with magnetic property, embedded in a polymeric (PMMA) matrix. EXPERIMENTAL METHODS The SC45 powders, (see1 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 were manually mixed for two minutes and subsequently put inside a mold, obtaining the composite cements. P10, P15, P20. Furthermore commercial cements were prepared as control. 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 an induction furnace at fixed frequency and alternate electromagnetic field. The samples were placed in a test tube containing 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 SEM-EDS analyses were carried out to evaluate 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 a maximum increasing temperature of 40°C that respect the limit imposed by hyperthermia therapy. 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 2012. SESSION  Materials and Devices for Emerging Clinical Challenges