Bioactivity of ferrimagnetic glass-ceramics in the system FeO---Fe2O3---CaO---SiO2

Bioactive and ferrimagnetic glass-ceramics are useful as thermoseeds for hyperthermia treatment of cancer. A heat treatment of a 40(FeO, Fe2O3)---60CaO·SiO2 wt% glass gives a ferrimagnetic glassceramic containing 36 wt% magnetite in a CaO·SiO2 matrix. However, it does not show bioactivity since a small amount of iron ion remains in the matrix. In the present study, bioactivities of ferrimagnetic glass-ceramics which were prepared by heat treatment of glasses of the composition 40(FeO, Fe2O3)---60CaO·SiO2 (wt%) with various components added at 100:3 weight ratio were evaluated in vitro by examining bone-like apatite formation on their surfaces in a simulated body fluid. It was found that glass-ceramics with Na2O or B2O3 added in combination with P2O5 show bioactivity.