Novel injectable degradable super-paramagnetic bone cement with self-controlled hyperthermia ability and enhanced radiopacity for the treatment of bone tumors
Magnetic hyperthermia using magnetic bone cement can not only realize the highly targeted treatment of the deep-seated bone tumor but also repair the weakened bone tissue, however, the potential risk of overheating is worrying and limits its use. Herein, we report a novel super-paramagnetic injectable radiopaque bone cement (MSBC) that can control hyperthermia temperature by itself. The MSBC has been prepared by incorporating SiO2-modified nano Mn-Zn-Cu-Gd ferrite to an acidic calcium phosphate cement matrix. Almost one-tenth of MSBC degrades after soaking in phosphate buffer solution for 28 days. Moreover, MSBC has a Curie temperature (Tc) of approximately 65 ℃ and displays doublet Mössbauer spectra and an S-like hysteresis loop with a saturated magnetization of 4.26 A•m2•kg-1 under a magnetic field of 1.2×106 A•m. The in vitro hyperthermia test using MSBC reveals that MSBC can realize self-controlled hyperthermia around Tc and achieve a cell mortality rate of 58%, effectively killing the cells within 5 mm around the material (Φ 9 mm × 2 mm) as a dead cell halo stained by trypan blue is observed under an alternating magnetic field (340 kHz, 1.13×103 A•m). The X-ray transmission results show that the radiopacity of MSBC has been significantly enhanced as compared to the matrix. Moreover, MSBC shows no cytotoxicity and can promote the mineralization ability of osteoblasts. Overall, this novel magnetic bone cement provides a new avenue for improving the thermal safety of magnetic hyperthermia treatment of bone tumors.