Self-assembled magnetic vesicles based on cationic double-chain dimethyldioctadecylammonium (DODMA(+)) encapsulating two kinds of magnetic polyoxometalates, K-10[Co-4(H2O)(2)(PW9O34)(2)]center dot 20H(2)O ({Co4P2W18}) and (Mo72Fe30O252L102)-Fe-VI-O-III center dot 180H(2)O with L = H2O/CH3COO-/Mo2O8/9n- ({Mo72Fe30}), were fabricated cated in mixed-solvent solution (CHCl3 + CH3OH, 4:1 v/v). The vesicles were characterized by scanning electron microscopy (SEM), transition electron microscopy (TEM), atomic force microscopy (AFM), and dynamic light scattering (DLS). SEM and TEM images show that three-dimensional hollow shells of the magnetic vesicles can survive after solvent evaporation. The room-temperature magnetic properties were measured, indicating that {Co4P2W18} and {Mo72Fe30} retain their magnetic properties after embedding in the vesicles. Interestingly, the self-assembled magnetic vesicles can be aligned under an external magnetic field, which make them ideal candidates as magnetic biosensors for drug-releasing materials. (C) 2009 Elsevier Inc. All rights reserved.