Preparation and characterization of chitosan–poly(acrylic acid) polymer magnetic microspheres

A modified method to prepare chitosan–poly(acrylic acid)(CS–PAA) polymer magnetic microspheres was reported in this paper. First, via self-assembly of positively charged CS and negatively charged Fe3O4 nanoparticles, magnetic CS cores with a large amount of Fe3O4 nanoparticles were successfully prepared. Subsequently, the AA monomers were polymerized on the magetic CS cores based on the reaction system of water-soluble polymer–monomer pairs. These polymer magnetic microspheres had a high Fe3O4 loading content, and showed unique pH-dependent behaviors on the size and zeta potential. From the magnetometer measurements data, the CS–PAA polymer magnetic microspheres also had superparamagnetic property as well as fast magnetic response. A continuous release of the entrapped ammonium glycyrrhizinate in such polymer magnetic microspheres occurred, which confirmed the potential applications of these microspheres for the targeted delivery of drugs.