Abstract: Magnetic chitosan-alginate microcapsules were prepared via emulsion-gel method. Fe3O4 magnetic hollow spheres were capsulated into the microcapsules, which endowed the microcapsules with magnetic targeting properties. Cefradine was used as model drug to study the properties of the microcapsules including drug content,encapsulation efficiency, and controlled drug release. The results showed that with the increasing of initial drug concentration, the drug content increased, but the encapsulation efficiency decreased. The microcapsules exhibited sustained release of the drug in all media and the release rate could be regulated by the pH value: in simulated gastric fluid, the release rate was greatly decreased, and in simulated body fluid and intestinal fluid, the microcapsules exhibited a constant release in 50 h with different release rates. Under an external magnetic field, the microcapsules showed fine magnetic response properties, which provided possibility for magnetic targeting drug delivery.

Key words: Microcapsule, Magnetic targeting, Controlled drug release, Magnetic hollow spheres, pH-responsive, Chitosan