A two-photon fluorescent sensor revealing drug-induced liver injury via tracking γ-glutamyltranspeptidase (GGT) level in vivo

Currently drug-induced liver injury (DILI) has become a major and challenging public health issue in terms of medicine development and clinical therapy. The level of γ-glutamyl transpeptidase (GGT) has long been regarded as a preclinical/clinical biomarker for prediction of DILI. Herein, we report a two-photon fluorescent sensor for tracking GGT level changes resulted from DILI in vivo. The sensor was prepared by linking a glutamic acid to a dicyanomethylene-4H-pyran (DCM) derivative; and the presence of GGT cleaves γ-glutamyl amide group from the sensor and thereby restores the fluorescence emission (at 635 nm) of DCM moiety under femtosecond pulses at 800 nm. This two-photon sensor exhibits superior sensing performance such as red emission, high photostability and low detection limit (∼0.057 U/L). On a two-photon microscope, the sensor shows a bright red fluorescence in GGT-overexpressing A2780 cells; and it can fluorescently respond to the GGT generated in the liver of zebrafishes as a result of clinical drug (phenytoin) treatment. These findings demonstrate that a commonly-used clinical drug phenytoin can cause remarkable elevation in GGT level in liver, and this sensor may be useful as a marker to detect clinical drug-induced organ damages.