Bismuth-based compounds are considered to be the best candidates for computed tomography (CT) imaging of gastrointestinal (GI) tract due to high X-ray absorption. Here, we report the introduction of polymer-coated bismuth oxychloride (BiOCl) nanosheets for highly efficient CT imaging in healthy mice and animal with colitis. We demonstrate simple, low cost and fast aqueous synthesis protocol which provides gram-quantity yield of chemically stable BiOCl nanosheets. The developed contrast gives 2.55-fold better CT enhancement compared to conventional contrast with negligible in vivo toxicity. As a major finding we report a regioselective CT imaging of GI tract by using nanoparticles coated with differentially charged polymers. Coating of nanoparticles with a positively charged polymer leads to their fast accumulation in small intestine, while the coating with negatively charged polymers stimulates prolonged stomach retention. We propose that this effect may be explained by a pH-controlled aggregation of nanoparticles in stomach. This feature may become the basis for advancement in clinical diagnosis of entire GI tract.

由于高 X 射线吸收，基于铋的化合物被认为是胃肠道 (GI) 计算机断层扫描 (CT) 成像的最佳候选者。在这里，我们报告了聚合物涂层氯氧化铋 (BiOCl) 纳米片的引入，用于在健康小鼠和结肠炎动物中进行高效 CT 成像。我们展示了简单、低成本和快速的水合成方案，该方案提供了化学稳定的 BiOCl 纳米片的克量产率。与传统造影剂相比，开发的造影剂 CT 增强效果提高了 2.55 倍，体内毒性可忽略不计。作为一项主要发现，我们报告了通过使用涂有不同电荷聚合物的纳米颗粒对胃肠道进行区域选择性 CT 成像。用带正电的聚合物包覆纳米颗粒会导致它们在小肠中快速积聚，而带负电聚合物的包覆会刺激延长胃滞留时间。我们提出这种效应可以通过胃中纳米颗粒的 pH 控制聚集来解释。这一特征可能成为推进整个胃肠道临床诊断的基础。