Synthesis of multifunctional superparamagnetic mesoporous ZnMnFe2O4@Fe-CaSiO3 core-shell for medical applications

Herein, we report the synthesis of a mesoporous calcium silicate superparamagnetic nanoparticle as ZnMnFe2O4@Fe-CaSiO3 core-shell. This core-shell nanocomposite reveals excellent properties such as meso-porous nanocomposite, superparamagnetic at room temperature, low toxicity, large surface area, tunable pore size, and easy surface manipulation. The core nanocomposite (ZnMnFe2O4) is synthesized by the hydrothermal method, which shows a superparamagnetic behavior with an excellent saturation magnetization of 52.09 emu/g. The core-shell structure is prepared by a micellar-assisted sol-gel method, which uses a copolymer to create pores in the structure of CaSiO3. To improve the magnetic properties of the core-shell structure, different percent of Fe ions (0%, 5%, and 10%) are doped onto the calcium silicate structure; as for 10% Fe, i.e., ZnMnFe2O4@-Fe10-CaSiO3, saturation magnetization and coercive magnetic field are 34.543 emu/g and 1Oe, respectively. In this configuration of nanocomposite, the pore volume and superparamagnetic property increase simultaneously. In addition, the core-shell mesoporous ZnMnFe2O4@Fe-CaSiO3 nanocomposite reveals comparable mesoporous channels (3.4-6 nm), while the amorphous structure of CaSiO3 has not been changed. These core-shell meso-porous superparamagnetic nanocomposites are evaluated in terms of drug loading and release using epirubicin (EPI) as a model drug. It is found that the increase of iron ions improves the capacity to stabilize the pH envi-ronment. Additionally, the mesoporous Fe-CaSiO3 nanostructures demonstrate a sustained drug release property that could be used in local drug delivery therapy. Therefore, these mesoporous superparamagnetic nano-structures would be a promising multifunctional platform for local drug delivery, magnetic resonance imaging, magnetic hyperthermia, and bone tissue regeneration.