Design and characterization of magnetic scaffolds for bone tumor hyperthermia

Magnetic tissue scaffolds are a promising powerful tool for performing interstitial tumor hyperthermia against the residual bone cancer cells, after surgical intervention. The design of the implant architecture is crucial for several biomedical requirements. However, to date, the influence of implant topology on the hyperthermia treatment outcome has never been assessed. Furthermore, the heating ability is a function of sample mass and geometry. In this work, a simple methodology for designing biomimetic scaffolds using triply periodic minimal surfaces is presented. A set of geometries is 3D printed by fused deposition modeling, using a commercial poly-lactic acid filament filled with magnetite particles, never tested for biomedical applications. Magnetic scaffolds were thoroughly characterized by performing static magnetic measurements, differential scanning calorimetric and thermogravimetric analysis, but, mostly, by carrying out calorimetric measurements to determine their hyperthermic potential under different experimental conditions. Numerical multiphysics simulations with a commercial finite element software were performed, resulting in good agreement with the measurements. The scaffolds were exposed to a magnetic field with 15 mT strength, working at 400 kHz, in air, and the surface temperature was recorder using infrared camera. The manufactured magnetic scaffolds can increase the temperature above 41°C (about 54-57°C), in 40-60 s. In distilled water, for a 30 mT magnetic field and 400 kHz, the temperature was recorded using an optic fiber and we observed that all the sample could be used as thermo-seed for cancer therapy. Finally, the scaffolds were tested in agarose phantoms and their hyperthermic potential was quantified.