A magnetic composite and the preparation and use

The invention belongs to the field of medicament and pharmaceutics, and relates to a magnetic compound. Specifically, the magnetic compound has a nuclear-casing structure, which means that an external layer is a segmented copolymer of chemical bond gathered basic amino acids or derivatives thereof, and a nuclear is metal oxide particles. A first block of the segmented copolymer is polyethylene glycol, and a second block is polyacrylic acid monoglyceride or polymethacrylic acid monoglyceride, wherein the second block is combined with surfaces of Fe3O4 particles. The invention also relates to apreparation method and a purpose of the magnetic compound. The magnetic compound of the invention not only has low toxicity, but also can permeate a cell membrane or even a karyotheca to enter a nucleus, or even pass through a blood cerebral barrier (BBB), so the magnetic compound can be used as a conveying carrier of various nucleic acids / medicaments.