Fig. 1.

Concept of fluorescence-guided detection of colorectal cancer using 6QC-ICG. (A) Chemical structure and schematic of the 6QC-ICG mechanism. (B) Schematic of a near-infrared (NIR) fluorescence endoscope used in the clinic. The probe is injected intravenously, and the GI physician uses an endoscope outfitted with an NIR (805/835 nm) detector and overlay fluorescence signals with a white-light image to detect lesion(s). (C) Sample image illustrating the concept of how our targeted fluorescent dye 6QC-ICG enables fluorescence-guided endoscopy of highlighted cancerous lesions that express cathepsins. Fluorescence is concentrated to the colorectal lesions and overlaid onto the white-light image.