High spatiotemporal tracking of intestinal peristalsis and bowel disease via in situ generated NIR-II cyanine-albumin complex

Real-time monitoring of intestinal movement is critical for the clinical diagnosis of bowel diseases, however, the application of organic fluorophores in non-invasive imaging of the intestinal tract via systemic administration is still challenging. We herein report a series of albumin-chaperoned chloro-cyanine dyes for high spatiotemporal tracking of intestinal peristalsis and bowel disease in vivo. By adjusting the size of the central rings, Cy7–5, with a five-membered ring and meso-chlorine, could covalently bind with circulating endogenous albumin in the blood, generating a bright and stable cyanine-albumin fluorescent complex with ∼1055 nm fluorescence in the near-infrared-II window in situ. Notably, Cy7–5 was able to clearly view intestinal peristalsis by harnessing the inherent intestine tropism of Cy7–5-albumin complex following intravenous (i.v.) administration. Furthermore, a hydroxyl radical (·OH)-activatable fluorophore (Hydro-Cy7–5) was created, allowing for the selective detection of overproduced ·OH in bowel disease as well as the successful visualization of the inflammatory intestinal tract in vivo after i.v. injection. This work provides a facile strategy for the investigation of intestinal movement and related diseases.