β-Glucuronidase-Activated Bioluminescence Probe for In Vivo Tumor Imaging

β-Glucuronidase (GLU) is a hallmark enzyme for many malignant tumors, but bioluminescence (BL) probes that enable GLU imaging in vivo have not been reported. Herein, we rationally designed the BL probe Glc-Luc to address this issue. In vitro results demonstrated the specific responsiveness of Glc-Luc toward GLU with a calculated catalytic efficiency (k_cat/K_m) of 0.0109 μM^-1 min^-1 and a limit of detection (LOD) of 1.39 U/mL. Moreover, Glc-Luc rendered 3.1-fold and 15.9-fold higher BL intensities over the control groups in cell lysates and tumor-bearing mice, respectively. We anticipate that Glc-Luc could be further applied for the sensitive diagnosis of GLU-related diseases.