Thermoresponsive hollow magnetic microspheres with hyperthermia and controlled release properties

Thermoresponsive hollow magnetic microspheres consisting of a hollow magnetic core, a carbon shell, and a smart polymer layer are presented in this article. A carbon nanomaterial was used as a steric stabilizer for Fe3O4 nanoparticles and a supporter for polymer. The thermoresponsive monomer, N-isopropyl acrylamide, was grafted on the carbon-encapsulate hollows by surface radical polymerization. The experimental results indicate that the composites had a phase-transition temperature around 43 degrees C and a saturation magnetization of 56.9 emu/g; this showed apparent thermosensitivity and magnetism. The performances in hyperthermia evaluated by an inductive magnetic field showed that the hybrid microspheres had a specific absorption rate of 240 W/g. The model drug, 5-fluorouracil, was loaded in and released from the microspheres with different release rates at 35 and 50 degrees C. This demonstrated that the as-synthesized microspheres had a thermotriggered release ability and would be a good drug carrier in the biomedical field. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42617.