Radiopaque iodinated polymeric nanoparticles for X-ray imaging applications.

Iodinated radiopaque polymeric nanoparticles of sizes ranging between 30 and 350 nm were formed by emulsion polymerization of the monomer 2-methacryloyloxyethyl(2,3,5-triiodobenzoate) in the presence of sodium dodecyl sulfate as surfactant and potassium persulfate as initiator. The influence of various polymerization parameters, e.g., monomer, initiator and surfactant concentrations on the molecular weight, polymerization yield, size and size distribution of the particles was elucidated. Characterization of these iodinated nanoparticles was accomplished by routine methods such as FTIR, 1H NMR, TEM, TGA, DSC, GPC and light scattering. These polymeric nanoparticles are composed of ca. 58% by weight iodine, and are therefore expected to possess significant radiopaque nature. In vitro radiopacity of the iodinated nanoparticles of 30.6+/-5.0 nm diameter, dispersed in water and in the dry state, was demonstrated with a CT scanner. In vivo CT-imaging performed in a dog model by intravenous administration of the uniform 30.6+/-5.0 nm diameter radiopaque nanoparticles dispersed in saline demonstrated significant enhanced visibility of lymph nodes, liver, kidney and spleen. These results indicate that these nanoparticles may be useful as new efficient contrast agents for X-ray imaging applications.