Intraoperative tumor margin delineation using a hybrid cyanine-rhodamine NIR-II fluorescent probe.

Second near-infrared (NIR-II, 900-1700 nm) fluorescence imaging, characterized by significantly reduced autofluorescence interference, enhanced tissue penetration, and improved in vivo resolution, has emerged as a promising modality for intraoperative tumor navigation. To harness its potential, it is highly important to develop safe and efficient NIR-II fluorescent probes for tumor targeting. Herein, we designed a sulfonated hybrid cyanine-rhodamine (SulfoHCR7) and conjugated it to a cyclic RGD pentapeptide (cRGD) to obtain a bright and highly tumor-targeting NIR-II fluorescent probe, named SulfoHCR7-cRGD. This probe exhibits a distinct absorption peak at 929 nm and an emission maximum at 1008 nm, along with excellent photostability and biocompatibility. We successfully applied SulfoHCR7-cRGD for in vivo visualization and fluorescence-guided resection of orthotopic and peritoneal breast tumors. Compared to the ICG-cRGD control, SulfoHCR7-cRGD demonstrated significantly enhanced tumor fluorescence, sharper tumor boundaries, and a higher signal-to-background ratio. These merits enabled clear localization and delineation of tumor tissues, making it a reliable molecular imaging tool for precise resection during surgery.