β-Cyclodextrin polymer brushes decorated magnetic colloidal nanocrystal clusters for the release of hydrophobic drugs

β-Cyclodextrin (β-CD) polymer brushes decorated magnetic Fe₃O₄ colloidal nanocrystal clusters (Fe₃O₄@PG-CD) were fabricated by a combination of surface-initiated atom transfer radical polymerization on the surface of Br-anchored Fe₃O₄ colloidal nanocrystal clusters (Fe₃O₄–Br) and ring-opening reaction of epoxy groups. The resulted Fe₃O₄@PG-CD hybrid nanoparticles were characterized by several methods including Fourier transform infrared, transmission electron microscope, dynamic light scattering instrument, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometer. Moreover, the potential of as-synthesized Fe₃O₄@PG-CD as a carrier of hydrophobic anticancer drug 5-fluorouracil (5-FU) was also investigated. The results showed that the prepared Fe₃O₄@PG-CD have core/shell structure and high saturated magnetism. 5-FU could be loaded into the Fe₃O₄@PG-CD via the formation of β-CD/5-FU inclusion complex. Furthermore, the Fe₃O₄@PG-CD displayed a high loading capacity and pH-dependent release behavior for 5-FU. The release behavior demonstrated a simple Fickian diffusion in the acidic environment (pH 2.0 and 4.0) but neither non-Fickian nor anomalous when neutral. The results reveal that this nanosystem seems to be a very promising vehicle for the hydrophobic drugs for pH-dependent controlled release.