PROBLEM TO BE SOLVED: To provide magnetic particles which can exhibit homogeneous functionality by being easily modified, can highly disperse in aqueous solvents, and can provide a magnetic particle-containing medicine for diagnosis, treatment, or the like, and to provide a dispersion containing the magnetic particles.SOLUTION: A composite magnetic particle powder is provided in which a particle surface of a magnetic nanoparticle with a primary particle diameter of 3-150 nm is covered with a first layer, a second layer, and a third layer in this order, the first layer is formed of a polymer having a carboxyl group, the second layer is formed of an amino acid or a polysaccharide, having a functional group selected from the group consisting of amino groups, carboxyl group, and hydroxyl groups, and the third layer is formed of an amino acid, a polysaccharide, and an imine, having a functional group selected from the group consisting of amino groups, carboxyl groups, hydroxyl groups, NOs, fluorescent dyes, a standard proteins, which can be modified with the functional groups of the second layer by an amide bond or an ester bond.COPYRIGHT: (C)2014,JPO&INPIT【課題】容易な修飾による均質な機能性を発揮でき、水系溶液に高分散な診断用・治療用などの磁性粒子含有医薬を生成できる磁性微粒子及び該磁性微粒子を含有する分散体を提供する。【解決手段】一次粒子径が3~150nmの磁性ナノ粒子の粒子表面が一層目、二層目及び三層目の順で被覆されており、前記一層目がカルボキシル基を有するポリマーであり、前記二層目はアミノ基、カルボキシキル基、水酸基からなる群から選ばれた官能基を有するアミノ酸、又は、多糖類であり、前記三層目は、二層目の官能基とアミド結合、エステル結合で修飾可能なアミノ基、カルボキシル基、水酸基、NO類、蛍光色素、標準タンパク質からなる群から選ばれた官能基を有するアミノ酸、多糖類、イミン類である複合磁性微粒子粉末である。【選択図】なし
