Multifunctional triple-porous Fe3O4@SiO2 superparamagnetic microspheres for potential hyperthermia and controlled drug release

Abstract

Magnetic porous particles with high magnetization and large surface area hold great potential for multimodal therapies. In this work, novel triple-porous Fe₃O₄@SiO₂ microspheres were synthesized by encapsulation of porous Fe₃O₄ with dual-porous SiO₂ shells. This novel triple-porous structure endows the microspheres with features of large surface area (426 m² g⁻¹) and pore volume; thus they could be used as an efficient drug delivery platform. These microspheres demonstrate superparamagnetic behavior with saturation magnetization of 52 emu g⁻¹. Measurements of AC magnetic-field-induced heating properties showed that the as-prepared microspheres could controllably generate heat to reach the hyperthermia temperature within a short time of exposure to an alternating magnetic field (AMF); hence they could be suitable as a hyperthermia agent for thermal therapy. Using a therapeutic agent 5-fluorouracil (5-Fu) as a model drug, the porous microspheres display high drug loading capacity, and sustained release behavior can be observed under the condition of no AMF actuation, while under the excitation of AMF, controlled drug release behavior can be achieved. Due to its magnetic field induced heating and AMF controlled drug release capabilities, this triple-porous nanomaterial provides an excellent platform for both hyperthermia treatment and drug delivery.