In Situ Generation of Red-to-NIR Emissive Radical Cations in Stomach for Gastrointestinal Imaging.

Red-to-NIR fluorescent probes with the advantages such as high spatiotemporal resolution and in situ sensing abilities are highly attractive for gastrointestinal disease diagnosis and targeted drug development. However, conventional red-to-NIR fluorophores with electron closed-shell structures require tedious synthetic procedures for preparation, and it is difficult to further decorate them with sensing groups. In this study, we developed a series of easily prepared pyrroles with simple structures that can quickly be transformed into red-to-NIR emissive radical cations in acidic buffer solution and in vivo stomachs. The in situ generated red-to-NIR emissive pyrrole radical cations in stomach have excellent biocompatibility and stability and can be used not only for intravital gastrointestinal imaging with high spatiotemporal resolution, but also for dynamic monitoring of the gastric emptying process and assessment of anti-gastric acid therapy. We believe the acidity-induced generation of pyrrole radical cations provides a facile strategy for developing red-to-NIR fluorophores and studying gastrointestinal diseases. This article is protected by copyright. All rights reserved.