Lighting up intestinal inflammation in situ with a pH-insensitive NIR fluorescent probe

Abstract

The accurate and sensitive in situ imaging of inflammatory bowel disease (IBD) is critical for the precise diagnosis and treatment of this disease, but it remains a challenge for fluorescent probes because of a more dynamical shift of pH in the intestinal tract than under other physical conditions. To address this issue, we report here that the rational introduction of the ortho-halogen bond at the electron acceptor can regulate the protonation and deprotonation of fluorescent dye, resulting in a pH-insensitive dye (pH 5–12). Therefore, constructing a near-infrared (NIR) probe, 2F-RBH, which effectively avoids this pH effect with a stable fluorescent signal and selectively indicates sites of inflammation in situ, by tracking peroxynitrite (ONOO−) in an acute colitis mouse model. Collectively, our results highlight that 2F-RBH is a promising probe for the imaging of IBD and that our pH-insensitive dye has potentially desirable properties for in vivo bioimaging.