Preparation, characterization, and evaluation of radiopaque hydrogel filaments for endovascular embolization

Radiopaque hydrogel filaments were prepared, characterized, and evaluated for potential use as implants for endovascular embolization of vascular defects. Three hydrogel formulations were prepared by free radical polymerization: (i) poly(ethylene glycol) diacrylate with 2,4,6-triiodophenyl penta-4-enoate (PEG-I), (ii) poly(ethylene glycol) diacrylamide with barium sulfate (PEG-B), and (iii) poly(propylene glycol) diacrylate with barium sulfate (PPG-B). The PEG-B and PPG-B hydrogels exhibited radiopacity comparable with clinically used platinum coils, whereas the PEG-I hydrogel did not. In the dry state, the average ultimate tensile strength and strain of the hydrogels ranged from 37 to 128 gf and 21% to 72%, respectively. The PEG-B hydrogel had significantly higher tensile strength compared with the PEG-I hydrogel. In the hydrated state, the average ultimate tensile strength and strain ranged from 5 to 15 gf and 7% to 30%, respectively. Statistically significant differences in tensile strength were not present when hydrated. Compared with poly(ethylene) after 4-week implantation into the subcutaneous space of rabbits, the PEG-I hydrogel elicited slightly more inflammation, whereas the PEG-B and PPG-B hydrogels elicited less inflammation. All three hydrogel formulations elicited less fibrous encapsulation than poly(ethylene). With further development, these materials have potential as embolization devices.