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 Fe 3 O 4 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°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°C. This demonstrated that the as‐synthesized microspheres had a thermotriggered release ability and would be a good drug carrier in the biomedical field. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42617.