Orally administered BiS@SiO core-shell nanomaterials as gastrointestinal contrast agents and their influence on gut microbiota.

Effective and safe contrast agents for X-ray computed tomography (CT) imaging of the gastrointestinal (GI) tract are quite desirable for realizing high diagnostic accuracy and low toxicity in the clinic. Herein, we synthesize a series of silica-coated bismuth sulfide core-shell nanomaterials (BiS@SiO) of various sizes and systematically study their GI CT contrast performance and potential toxic effects in comparison with those of barium sulfate (BaSO) in mice. The experimental results suggest that these BiS@SiO core-shell nanomaterials display superior CT contrast performance and higher elimination efficacy than BaSO by single-dose exposure manner (10 ​mg/kg Bi element/b.w. for BiS@SiO versus 30 ​mg/kg Ba element/b.w. for BaSO). Furthermore, 28 days after exposure, BiS@SiO core-shell nanomaterials show minimal toxic effects and nonsignificant influences on the structure and function of the gut microbiota in mice. This demonstrates that no adverse effects on the gut homeostasis are induced by BiS@SiO core-shell nanomaterials and, thus, suggests that they can act as excellent and safe CT contrast agents for GI tract imaging.