Preparation of Magnetic Temperature-responsive Composite Microspheres and Their Drug-release Behaviors under an AC Magnetic Field

Abstract:

Magnetic and temperature-responsive polymer microspheres, consisting of superparamagnetic Fe3O4 nanopaticles and temperature-responsive poly(N-isopropylacrylamide-co-acrylamide) (PNIPAAm-co-Am) microgel, were prepared by soap-free emulsion free copolymerization. Their heating generation abilities and drug release behaviors were investigated under an AC magnetic field of 60kHz and 6.5kA/m. Results showed that the as-synthesized Fe3O4/(PNIPAAm-co-Am) composite microspheres exhibited high heating generation ability. The temperature of 42°C, which is close to the lower critical solution temperature (LCST) of the temperature-responsive polymer, was achieved after the composite microspheres were exposed to an AC magnetic field for 20min. The drug release profiles showed that longer release duration and larger overall release could be achieved by intermittent application of a magnetic field as compared to continuous magnetic field. With high heating generation ability and controlled drug release property, such Fe3O4/(PNIPAAm-co-Am) polymer microspheres are promising for the combination of tumor hyperthermia and controlled release of chemotherapy drugs.

Key words:Magnetic composite microspheres; Drug release; Fe3O4; Poly(N-isopropylacrylamide)