A Photoelectrochemical Sensor for Glutathione Detection Based on a Target-triggered Etching Strategy

A highly efficient photoelectrochemical (PEC) biosensor for glutathione (GSH) assay was constructed based on the target-triggered etching of CdS@MnO 2 nanocomposites (NCs). The core–shell CdS@MnO 2 NCs were prepared by a hydrothermal method and coated on the indium tin oxide (ITO) electrode as a PEC sensing platform. The PEC sensing platform gave a near-zero PEC signal due to the excellent light absorption ability of MnO 2 nanosheet coating on the CdS nanoparticles. In the presence of GSH, the etching of MnO 2 on the CdS@MnO 2 NCs was triggered because of the unique etching reaction between MnO 2 and GSH, leading to the exposure of inner photoactive nanomaterials, i.e., CdS in this system. This inevitably causes an obvious increase in the photocurrent response, which is related to the GSH concentration. Thanks to the excellent quenching effect of MnO 2 on the PEC signal of CdS, acceptable PEC performance of CdS, and the specific interaction between GSH and MnO 2 , the targets-triggered etching strategy exhibited excellent analytical performance for GSH detection with a detection limit of 0.05 μmol/L and a linear range from 0.2 to 100 μmol/L. The PEC biosensor has advantages such as good selectivity, excellent stability, and low background. This work contributed a fresh idea to detect GSH sensitively through the PEC sensing method.