Novel biocompatible pH-stimuli responsive superparamagnetic hybrid hollow microspheres as tumor-specific drug delivery system

Novel biocompatible pH-stimuli responsive superparamagnetic hybrid hollow microspheres have been designed via the layer-by-layer (LbL) self-assembly technique via the electrostatic interaction between the poly(ethylene glycol) grafted chitosan (CS-g-PEG) as polycation and the citrate modified ferroferric oxide nanoparticles (Fe3O4–CA) as hybrid anion onto the uniform polystyrene sulfonate (PSS) microsphere templates. The well-defined hybrid hollow microspheres ((CS-g-PEG/Fe3O4–CA)4/CS-g-PEG) were obtained after etching the templates by washing with DMF. They possessed superparamagnetic characteristics with a saturation magnetization of 37.23 emu/g, and exhibited excellent stability in high ion-strength media and pH dependent DOX release. Their unique structure and outstanding performance make them potential platform for tumor-specific delivery in the tumor diagnostic and therapy.