  Magnetic bioactive glass ceramic (MGC) powders have been synthesized by sol
gel route by systematically substituting silicon dioxide with iron oxide in the
45S5 glass composition. Powder x-ray diffraction studies revealed a variation
in the percentage of combeite (Ca$_2$Na$_2$Si$_3$O$_9$), magnetite
(Fe$_3$O$_4$), and hematite (Fe$_2$O$_3$) nanocrystalline phases in MGC powders
as a function of composition. Zeta potential measurements showed that MGC
containing up to 10 wt.% iron oxide formed stable suspensions. Saturation
magnetization and heat generation capacity of MGC fluids increased with
increase in iron oxide content. Degradation of MGC powders was investigated in
phosphate buffer saline (PBS). In vitro bioactivity of the MGC powders taken in
pellet form was confirmed by observing the pH variation as well as
hydroxyapatite layer (HAp) formation upon soaking in modified simulated body
fluid. These studies showed a decrement in overall bioactivity in samples with
high iron oxide content due to the proportional decrease in silanol group.
Monitoring the proliferation of MG-63 osteoblast cell in Dulbecco's Modified
Eagle Medium (DMEM) revealed that MGC with up to 10 wt.% iron oxide exhibited
acceptable viability. The systematic study revealed that the MGC with 10 wt.%
iron oxide exhibited optimal cell viability, magnetic properties and induction
heating capacity which were better than those of FluidMag-CT, which is used for
hyperthermia treatment.
