A highly sensitive and selective two-photon fluorescent probe for glutathione S-transferase detection and imaging in living cells and tissues.

Glutathione transferase (GST) is a very important metabolic enzyme that mediates the wide metabolism of endogenous and xenobiotic compounds; it usually has a significant over expression in cancer cells, which is a key reason resulting in drug resistance, and will show an obvious down regulation during liver injury, thus it was also regarded as a vital biomarker in clinical diagnosis. Herein, based on boron-dipyrromethene (BODIPY) dye, a two-photon probe BNPA was designed for the real-time detection of GST activities and fluorescence imaging in both cancer cells and liver tissues. Importantly, BNPA exhibited a high selectivity, ultrahigh imaging resolution and showed a classic Michaelis-Menten kinetics toward GSTs. Furthermore, it was successfully used for monitoring the GST activities in living cells and deep tissues by two-photon imaging, as well as detecting the down regulation of GST activities during α-naphthylisothiocyanate (ANIT) induced liver injury. Our results fully demonstrated that BNPA could serve as a promising tool for evaluating the GST function and the process of cellular GSTs in living systems, and also provided a new approach for studying GST-associated liver diseases, which would be greatly useful for rational drug use and disease diagnosis in clinics.