γ-Glutamyltranspeptidase (GGT) is a cell surface-bound enzyme that is closely implicated in various physiological disorders such as tumor. Thus, an efficient method for monitoring GGT is extremely important for biological studies and disease diagnosis. Herein, a near-infrared fluorescent probe (TMN-Glu) has been developed for turn-on trapping of GGT activity in vitro and in vivo based on conjugating a dicyanoisophorone derivative fluorophore with a GGT activatable γ-glutamyl amide moiety. Advantages of the probe include near-infrared emission (658 nm), with large Stokes shift (213 nm), high specificity, high sensitivity (LOD = 0.024 U/L), low cytotoxicity and high imaging resolution, allowing for the real-time imaging endogenous GGT in living cells. Probe TMN-Glu was highly feasible to report on the GGT levels in different types of cells. Notably, we also demonstrated its applicability in real-time visualizing endogenous GGT in tumor-bearing nude mice with low background interference. These results indicated that the probe held great promise for real-time sensing and tracking GGT in complex biological systems, which would be useful for basic researches and clinical diagnosis of GGT-related diseases.

γ-谷氨酰转肽酶（GGT）是一种细胞表面结合酶，与多种生理疾病（例如肿瘤）密切相关。因此，监测GGT的有效方法对于生物学研究和疾病诊断极为重要。在本文中，基于将双氰基异佛尔酮衍生物荧光团与GGT可活化的γ-谷氨酰胺基团缀合，已经开发了用于在体外和体内开启捕获GGT活性的近红外荧光探针（TMN-Glu）。该探针的优势包括近红外发射（658 nm），大斯托克斯位移（213 nm），高特异性，高灵敏度（LOD = 0.024 U / L），低细胞毒性和高成像分辨率，可实现实时成像活细胞中的内源性GGT。探测TMN-Glu在报告不同类型细胞中的GGT水平方面非常可行。值得注意的是，我们还证明了其在实时可视化具有低背景干扰的荷瘤裸鼠中内源GGT的适用性。这些结果表明，该探针对于复杂生物系统中GGT的实时传感和跟踪具有广阔的前景，将为GGT相关疾病的基础研究和临床诊断提供参考。