The anisotropic biotinylated latex fine particles are obtained by substituting an epoxy side with biotin by using anisotropic latex fine particles having a hydroxy group which exists in a domain A in a wide region and an epoxy group which exists in a narrow domain B and biotinylating only one side of fine particles. 広い領域のドメインAにある水酸基と狭い領域のドメインBにあるエポキシ基を、それぞれ微粒子に持たせた異方性ラテックス微粒子を用いて、エポキシ側をビオチンに置き換えて、微粒子の片側のみをビオチン化した異方性ビチオン化ラテックス微粒子。 - 特許庁