Alginate-based ferrofluid and magnetic microsphere thereof

The Fe₃O₄ ferrofluids have been prepared using sodium alginate (Na-AL) as a stabilizing agent. The alginate can prevent the aggregation of magnetic nanoparticles and hence contributed to higher stability for the ferrofluids. Furthermore, the alginate component in the ferrofluids was crosslinked by Ca²⁺ to produce magnetic microspheres. The swelling behavior of magnetic microspheres showed a pH-dependence, and hence determined the drug release process under various pH conditions. The presence of the Fe₃O₄ nanoparticles made the magnetic microspheres swell more easily. Meanwhile, the strong ability to absorb the drug for the incorporated Fe₃O₄ nanoparticles decreased the release rate and hence was more favorable to the sustaining release of drug. Except for the controlled delivery and release of drug, the alginate-based ferrofluids and magnetic microspheres in this work might also show a great potential for other biomedical and biotechnological applications, such as, magnetic targeting, magnetic separation and magnetic resonance imaging.