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).