Patent ID: 8871180

Claim:
An organic-inorganic hybrid particle comprising as essential components, a block copolymer comprising a structure represented by a formula (I): poly(hph)-block-poly(carbo) (I) wherein poly(hph) represents a hydrophilic polymer chain segment derived from a water-soluble polymer selected from the group consisting of poly(ethylene glycol), poly(2-methyl-2-oxazoline), poly(2-ethyl-2-oxazoline), poly(2-isopropyl-2-oxazoline), poly(acrylamide), poly(methacrylamide), poly(vinyl alcohol), poly(hydroxyethyl acrylate) and poly(hydroxyethyl methacrylate); poly(carbo) represents a polymer chain segment containing a recurring structural unit having a carboxylate ion group at its side chain, wherein the polymer chain segment is derived from the group consisting of poly(asparatic acid), poly(glutamic acid), poly(acrylic acid), poly(methacrylic acid), poly(malic acid) and random or block copolymers produced from at least two monomers for making these polymers; a calcium ion (Ca 2 +); at least one anion selected from the group consisting of a phosphate ion (PO 4 3− ), a carbonate ion (CO 3 2− ), and a mixture thereof; and a contrast agent; wherein the calcium ion and the phosphate ion form amorphous fine agglomerates, and the calcium ion and the carbonate ion form amorphous fine agglomerates, and the hybrid particle is in the form of an aqueous dispersion in an aqueous medium, and has an average particle diameter within a range of 10 nm to 1000 nm, as measured by dynamic light-scattering of the dispersion, and wherein the contrast agent is adhered onto a surface of the amorphous fine agglomerates or is wholly encapsulated by the amorphous fine agglomerates and is a metal selected from the group consisting of gadolinium (Gd), europium (Eu), manganese (Mn), iron (Fe) and copper (Cu), and is in the form of a metal chelate with an aminocarboxylic acid or phosphoric acid system polydentate ligand.