Silicon Rhodamine-Based Near-Infrared Fluorescent Probe for γ-Glutamyltransferase.

We designed and synthesized an activatable near-infrared (NIR) fluorescent probe for γ-glutamyltransferase, based on an asymmetric silicon rhodamine scaffold with an optimized equilibrium of intramolecular spirocyclization. The synthesized probe exhibits dramatic NIR fluorescence activation and, in combination with previously reported probes, enables discrimination of tumors with different enzymatic profiles.