Reversible linear assemblies of superparamagnetic Fe3O4/PLGA composite microspheres induced by ultra-low magnetic field

The hollow Fe3O4/poly (lactic-co-glycolic acid) (PLGA) composite microspheres have been successfully prepared via emulsion–solvent evaporation method. The composite microspheres exhibited superparamagnetism, good magnetic response and narrow size distribution. The composite microspheres could assemble into linear aligned arrays under an ultra-low magnetic field. Once the ultra-low magnetic field was removed, the linear assemblies could be easily re-dispersed in aqueous solution to recover to the assembly units, namely the Fe3O4/PLGA composite microspheres. Such reversibly transformational morphologies between the linear assemblies and the assembly units would contribute to giving full play to the functions of the material.