Bioinspired Formation of 3D Hierarchical CoFe<sub>2</sub>O<sub>4</sub> Porous Microspheres for Magnetic-Controlled Drug Release

Bioinspired by the morphology of dandelion pollen grains, we successfully prepared a template-free solution-based method for the large-scale preparation of three-dimensional (3D) hierarchical CoFe<sub>2</sub>O<sub>4</sub> porous microspheres. Besides, on the basis of the effect of the reaction time on the morphology evolution of the precursor, we proposed an in situ dissolution–recrystallization growth mechanism with morphology and phase change to understand the formation of dandelion pollenlike microspheres. Doxorubicin hydrochloride, an anticancer drug, is efficiently loaded into the CoFe<sub>2</sub>O<sub>4</sub> microspheres. The magnetic nanoparticles as field-controlled drug carriers offer a unique power of magnetic guidance and field-triggered drug-release behavior. Therefore, 3D hierarchical CoFe<sub>2</sub>O<sub>4</sub> porous microspheres demonstrate the great potential for drug encapsulation and controlled drug-release applications.