Synthesis of magnetic FexOy@silica-pillared clay (SPC) composites via a novel sol–gel route for controlled drug release and targeting

Novel magnetic silica-pillared clay (SPC) materials with an ordered interlayered mesopore structure were synthesized via a two-step method including gallery molecular self-assembly and sol–gel magnetic functionalization, resulting in the formation of FexOy@SPC composites. Small-angle XRD, TEM and N2 adsorption–desorption isotherms results show that these composites conserved a regular layered and ordered mesoporous structure after the formation of FexOy nanoparticles. Wide-angle XRD and XPS analyses confirmed that the FexOy generated in these mesoporous silica-pillared clay hosts is mainly composed of γ-Fe2O3. Magnetic measurements reveal that these composites with different γ-Fe2O3 loading amounts possess super-paramagnetic properties at 300 K, and the saturation magnetization increases with increasing Fe ratio loaded. Compared to the pure SPC, the in vitro drug release rate of the FexOy@SPC composites was enhanced due to the fact that the intensities of the SiOH bands on the pore surface of SPC decrease after the generation of FexOy. However, under an external magnetic field of 0.15 T, the drug release rate of the FexOy@SPC composites decreases dramatically owing to the aggregation of the magnetic FexOy@SPC particles triggered by non-contact magnetic force. The obtained FexOy@SPC composites imply the possibility of application in magnetic drug targeting.