2-Mercaptobenzothiazole-supported ratiometric fluorescent copper nanoclusters for activatable GSH sensing to drive tumor recognition

The development of GSH (one of tumor biomarkers)-specific response fluorescent sensor that are free from environmental and instrument interference, is pivotal to precisely recognize tumor in biological systems. Herein, a novel activatable ratiometric fluorescent copper nanocluster (MBT@PVP-CuNCs) biosensor was designed by one-pot approach at room temperature. The dual-emission biosensor can be applied to ratiometric (F585 nm/F432 nm) GSH sensing with high selectivity and sensitivity (0.28 μM) based on polyvinylpyrrolidone (PVP) as a reference signal and 2-mercaptobenzothiazole (MBT) induced AIE copper nanoclusters (MBT@PVP-CuNCs) as response signal. Besides, confocal laser imaging showed that the biosensor has prominent cell permeability and lysosome-targeting ability, which successfully applied to real-time imaging of intracellular GSH in different living cells. Excitingly, fluorescence imaging in BALB/c nude mice demonstrated that MBT@PVP-CuNCs can effectively determine the variation of GSH in vivo and realize tumor visualization. Furthermore, homemade test strips that are visible to naked eye were established for colorimetric determination of GSH with good portability and usefulness. The present work introduces an environmentally friendly and flexible strategy to design tumor marker-activated biosensors for achieving the cancer recognition through GSH levels determination in clinical application.