A core-shell particle including a
signal-generating substance therein, wherein the core-shell particle consists of (1) a core portion substantially made of a water-insoluble
polymer compound; and (2) a shell portion substantially made of a water-
soluble polymer compound having a reactive functional group, and covering a surface of the core portion in the manner of bristles of a
brush; and the core portion and the shell portion are, as a whole, a block
copolymer of a water-insoluble
polymer and a water-
soluble polymer, characterized in that the
signal-generating substance is included in the core portion, is disclosed, and a process for producing the same is also disclosed.The core-shell particle including a
signal-generating substance therein is useful as a labeling substance in which neither radioisotopes having handling restrictions nor unstable enzymes are required, a high sensitivity superior to fluorescent substances is achieved, and nonspecific absorption does not occur.