ORGANIC-INORGANIC HYBRID PARTICLES CONTAINING CONTRAST AGENT
This invention provides organic-inorganic hybrid particles containing as the essential components a block copolymer comprising an uncharged hydrophilic polymer chain segment and a polymer chain segment containing a repeated structural unit having a carboxylate ion group at its side chain
calcium ion (Ca2+), phosphate ion (PO4 3-) or carbonate ion (CO 3 2-), or a mixture of these anions
and a contrast agent. The particles provide, in particular, carriers for stably delivering an MRI contrast agent to a target site.