Fabrication of gelatin Bi 2 S 3 capsules as a highly sensitive X-ray contrast agent for gastrointestinal motility assessment in vivo .

Tiny BaSO 4 rod-based X-ray imaging is the most frequently-used method for clinical diagnosis of gastrointestinal motility disorders. The BaSO 4 rods usually have a small size to pass through the gastrointestinal tract smoothly, but suffer from unavoidably low sensitivity. Herein, we developed Bi 2 S 3 capsules as a high-performance X-ray contrast agent for gastrointestinal motility assessment for the first time. The Bi 2 S 3 capsules were synthesized by the encapsulation of commercial Bi 2 S 3 powder into commercial gelatin capsules and subsequent coating of ultraviolet-curable resin. The prepared Bi 2 S 3 capsules showed excellent biocompatibility in vitro and in vivo and superior X-ray attenuation ability due to the large atomic number and high K-edge value of Bi. The developed Bi 2 S 3 capsules can serve as a small but highly sensitive X-ray contrast agent to quantitatively assess gastrointestinal motility in a vincristine-induced gastrointestinal motility disorder model in vivo by X-ray, CT and spectral CT imaging successfully, solving the intrinsic drawbacks of clinically used BaSO 4 .