Synthesis and Characterization of Dual-Magnetic Thermosensitive Microspheres

Abstract

Fe 3 O 4 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 Fe 3 O 4 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 Fe 3 O 4 nanoparticles shows no influence on the inverse cubic spinel phase of Fe 3 O 4 . 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.