The present invention provides an amphiphilic polymer, poly(ethylene glycol)-b-poly(ε-caprolactone)-poly(acrylic acid) (“PAA-PEC”), which is made by synthesizing poly(ethylene glycol)-b-poly(ε-caprolactone) (“PEG-PCL”) with an ring-opening reaction and then grafting the hydroxyl group of PEG-PCL with the carboxyl group of poly(acrylic acid) (“PAA”). PAA-PEC with multiple functions may be chemically or physically coated onto magnetic Fe3O4, wherein the chemically PAA-PEC-coated iron oxide (PAA-PEC-IO) nanoparticles are prepared by a simple reaction whereas oleic acid-coated Fe3O4(OA-IO) is physically encapsulated into the PAA-PEC core to form PAA-PEC-OA-IO via an emulsion technique. The magnetic nanoparticles of the present invention own high drug entrapment efficiency, high biological compatibility, low cytotoxicity and high capability for magnetic resonance imaging (MRI) technique.本發明揭示一種雙性接枝高分子,其係以開環反應合成出聚乙二醇-聚己內酯分子(PEG-PCL,簡稱PEC),再以PEC分子的羥基與聚丙烯酸(PAA)的羧基進行接枝反應,而形成該雙性接枝高分子PAA-PEC。該雙性接枝高分子具備多功能,可以以化學鍵結方式裹覆在磁性奈米氧化鐵粒子的表面,或者,以乳化之物理方式,將油酸包覆的脂溶性氧化鐵包覆於PAA-PEC核心,製備成水溶性磁性奈米粒子。本發明獲得的磁性奈米顆粒具有高藥物包覆率、高生物相容性、高藥物毒殺能力、高核磁共振成像能力。PAA‧‧‧聚丙烯酸PEG-PCL‧‧‧聚乙二醇-聚己內酯PAA-PEC‧‧‧聚乙二醇-聚己內酯-聚丙烯酸PAA-PEC-IO‧‧‧聚乙二醇-聚己內酯-聚丙烯酸磁性奈米氧化鐵微粒
