Synthesis and characterization of uniform radiopaque polystyrene microspheres for X-ray imaging by a single-step swelling process

Uniform radiopaque polystyrene microspheres of ∼2.3 ± 0.2 μm were prepared by a single-step swelling of 2.3 ± 0.2 μm polystyrene template microspheres, dispersed in an aqueous solution with methylene chloride emulsion droplets containing 2,3,5-triiodobenzoylethyl ester. After completing the swelling process, the methylene chloride was evaporated in order to lock the 2,3,5-triiodobenzoylethyl ester in the polystyrene microspheres. The influence of the weight ratio [2,3,5-triiodobenzoylethyl ester]/[polystyrene] on the % of entrapped 2,3,5-triiodobenzoylethyl ester was elucidated. Characterization of the radiopaque polystyrene microspheres was accomplished by light microscope, FTIR, TGA, SEM, XPS, and elemental analysis. The radiopacity of the microspheres was demonstrated by an imaging technique based on X-ray absorption usually used in hospitals. This novel method of encapsulation of 2,3,5-triiodobenzoylethyl ester within polystyrene microspheres by a single-step swelling process may be used as a model for encapsulation of various hydrophobic radiopaque drugs within uniform polystyrene template particles of various diameters for different X-ray imaging needs, e.g., blood pool, body organs, embolization, dental composition, implants, protheses, and nanocomposites.