Preparation and characterization of smart magnetic hydrogels and its use for drug release

The magnetic hydrogels were successfully fabricated by chemically cross-linking of gelatin hydrogels and Fe₃O₄ nanoparticles (ca. 40-60 nm) through genipin (GP) as cross-linking agent. The cross-sectional SEM observation demonstrates that the Fe₃O₄ nanoparticles were fairly uniformly distributed in the gelatin matrix. Moreover, in vitro release data reveal that drug release profile of the resulting hydrogels is controllable by switching on or off mode of a given magnetic field. While applying magnetic fields to the magnetic hydrogels, the release rate of vitamin B₁₂ of the hydrogels was considerably decreased as compared with those when the field was turned off, suggesting a close configuration of the hydrogels as a result of the aggregation of Fe₃O₄ nanoparticles. Based on this on-&-off mechanism, the smart magnetic hydrogels based on the gelatin-ferrite hybrid composites can be potentially developed for application in novel drug delivery systems.