Innovative diopside-MnFeO nanocomposites: a multifunctional platform for bone regeneration and hyperthermia therapy featuring MnFeO nanoparticles with near-bulk magnetic performance.

This study explores the novel integration of MnFeO nanoparticles into diopside bioceramics, paving the way for advanced multifunctional nanocomposites tailored for orthopedic and oncological applications. Diopside is synthesized using biowaste-derived eggshells and rice husks solid-state reaction at an optimal sintering temperature of 1200 °C. MnFeO nanoparticles, with an average particle size of 46 nm, are produced through a facile hydrothermal method coupled with magnetic separation, achieving an impressive saturation magnetization () of 81.6 emu g (99.5% of bulk MnFeO) - the highest reported to date. This exceptional performance is attributed to the nanoparticles' excellent crystallinity, single-domain behavior, and minimized surface effects. Incorporating MnFeO nanoparticles into diopside significantly enhances the sinterability, density, and hardness by 2-2.5 times while reducing porosity to ∼1%. Even at a low addition of 10 wt% MnFeO, the nanocomposites demonstrate effective hyperthermia within a safe therapeutic range (41-46 °C) under an alternating magnetic field, with negligible coercivity and remanence. Biocompatibility evaluations confirm no cytotoxicity and reveal enhanced osteoblast differentiation and mineralization. This study successfully synthesizes MnFeO nanoparticles with near-bulk saturation magnetization and highlights diopside-MnFeO nanocomposites as promising candidates for sustainable and multifunctional biomaterials, offering load-bearing support, efficient hyperthermia for osteosarcoma therapy, and accelerated bone regeneration.