A multifunctional near-infrared fluorescent probe for in vitro and in vivo imaging of γ-glutamyltranspeptidase and photodynamic cancer therapy

The excessive expression of gamma-glutamyltranspeptidase (GGT) is known to be closely associated with the progression, invasion and metastasis of malignant tumors, enabling GGT to be a cancer-related biomarker for cancer diagnosis. The development of the multifunctional fluorescent probe that combines GGT measurement and photodynamic therapy (PDT) into a single platform possesses exciting prospect for concurrent tumor diagnosis and treatment. In this study, we designed a new near-infrared (NIR) fluorescent probe (CyI-Glu) with therapeutic function which could realize the integration of fluorescence endogenous GGT visualization for tumor diagnosis and NIR imaging-guided tumor photodynamic therapy. CyI-Glu manifested a significant turn-on NIR fluorescence (718 nm) in response to GGT, which made it favorable for monitoring GGT activity with high selectivity and sensitivity (0.014 U/L) in vitro and in vivo. Furthermore, this GGT-responsive probe possessed improved ROS generation capacity for tumor cell apoptosis and tumor growth inhibition under NIR light irradiation. Collectively, the multifunctional fluorescent probe CyI-Glu with complementary advantages demonstrates significant potential for the diagnosis and treatment of tumors in complex organisms.