The present invention belongs to the field of composite material and biomedicine technology, and is especially preparation process of biodegradable magnetic medicine carrying polymer microsphere. The present invention prepares the magnetic microsphere for coating liposoluble medicine through a phase separating process with nanometer Fe3O4 as magnetic seed and biodegradable polymer as carrier material. The preparation process includes ultrasonically dispersing nanometer Fe3O4 particle in oil phase of acetone solution of polymer and medicine; dropping the oil phase into water phase, which is water solution of Tween-80, water solution of PVA or distilled water; stirring to volatilize acetone; repeated dialysis and eccentric separation to eliminate un-coated medicine and free magnetic particle; and final freeze drying. The microsphere has excellent dispersivity, size below 380nm, Fe3O4 content of 4-8 % and medicine coating rate of 9-17 %, and is used as novel medicine carrier. |