Synthesis and Characterization of Dual-Magnetic Thermosensitive Microspheres

Fe3O4 nanoparticles and poly(N-isopropylacrylamide-co-methacrylic acid) were combined to form dual-magnetic thermosensitive microspheres. The results of fourier-transform infrared (FTIR) spectroscopy, transmission electron microscope (TEM) and thermogravimetric analyzer (TGA) confirm that the microspheres are characterized with a magnetic Fe3O4 core, a poly(N-isopropylacrylamide-co-methacrylic acid) shell, and an average diameter of about 150-300nm. Spectra of wide angle X-ray diffraction (WAXD) indicate that the copolymer on the surface of Fe3O4 nanoparticles shows no influence on the inverse cubic spinel phase of Fe3O4. The lower critical solution temperature (LCST) of the thermosensitive copolymer-shell is about 39°Cas determined by a turbidimeter. Besides, the microspheres exhibit an obvious advantage using magnetic separation, and can be heated through an external alternating magnetic field to generate thermal effects, thus possess dual-magnetic responses (including magnetic delivery and magnetic-thermal effects). The synthesized microspheres with dual-magnetic and thermosensitive responses have potential applications in a magnetic drug-targeting delivery system for controlled drug release.