Fe₃O₄@Void@Microporous Organic Polymer-Based Multifunctional Drug Delivery Systems: Targeting, Imaging, and Magneto-Thermal Behaviors

Multifunctional drug delivery systems were designed and engineered by template synthesis of a microporous organic polymer (MOP) and by postsynthetic modification. Hollow MOP spheres bearing Fe3O4 yolks (Fe3O4@Void@MOP) were prepared by the synthesis of MOP on Fe3O4@SiO2 nanoparticles and by successive silica etching. In addition to the magneto-thermal function of Fe3O4 yolks, an aggregation-induced emission (AIE) feature was incorporated into the Fe3O4@Void@MOP through a homocoupling of tetra(4-ethynylphenyl)ethylene to form Fe3O4@Void@MOP-TE. Folate groups were further introduced into Fe3O4@Void@MOP-TE through the postsynthetic modification based on the thiol-yne click reaction. The resultant Fe3O4@Void@MOP-TE-FA showed multifunctionality in antitumoral therapy via folate receptor targeting, doxorubicin delivery, AIE-based imaging, and the magneto-thermal feature.