Patent ID: 8801955

Claim:
A method of producing water-soluble nanoparticles, comprising: (1) synthesizing water-insoluble metal oxide nanoparticles in an organic solvent comprising an organic surface stabilizer by a thermal decomposition without using an oxidizing or a reducing agent; (2) dissolving the water-insoluble nanoparticles in a first solvent and dissolving at least one water-soluble multifunctional group ligand comprising an adhesive region (L I ), a cross-linking region (L II ), and a reactive region (L III ) which contains a functional group capable of adhering to an active component, in a second solvent; (3) mixing two solutions in the step (2) to substitute organic surface stabilizers of the water-insoluble nanoparticles with the at least one water-soluble multifunctional group ligand and dissolving a mixture in an aqueous solution to conduct a separation process, wherein water-soluble nanoparticles are obtained; and (4) cross-linking the substituted multifunctional group ligands with each other on the water-soluble nanoparticles to stabilize the water-soluble nanoparticles; wherein the water-soluble nanoparticles are each surrounded by multifunctional group ligands, and wherein the cross-linking region of the multifunctional group ligands is cross-linked with the cross-linking region of a neighboring multifunctional group ligand.