Preparation of magnetic microgels based on dextran for stimuli-responsive release of doxorubicin

Hydrogel nanocomposites incorporated with magnetic nanoparticles (MNPs) were widely researched as promising candidate for environment-responsive drug delivery, due to their unique magnetic properties and quick response to an external magnetic field. In this study, dextran-coated iron oxide nanoparticles (Fe3O4) with various particle size were prepared and embedded physically into dextran microgels formed via Schiff base reactions between aldehyded dextran and diamine in W/O inverse microemulsion, leading to a series of magnetic microgels with MNPs content of 3, 6, 9% by weight percentage. Similar superparamagnetic properties of as prepared microgels with Fe3O4 nanoparticles were proved, and their saturation magnetization increased with the increasing particle size or content of the MNPs. Antitumor drug doxorubicin (DOX) was encapsulated into the magnetic dextran microgels, and pH/magnetic field dual-responsive release profiles of DOX were demonstrated. Moreover, the release rate of DOX decreased obviously with the increasing MNPs content, probably due to the diffusion barrier for drug movement resulted from the reduced pore size of hydrogel matrix in respond to external magnetic field. These results indicate that the magnetic dextran microgels can serve as stimuli-sensitive drug delivery systems.