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@MnO2 nanocomposites (NCs). The core-shell CdS@MnO2 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 MnO2 nanosheet coating on the CdS nanoparticles. In the presence of GSH, the etching of MnO2 on the CdS@MnO2 NCs was triggered because of the unique etching reaction between MnO2 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 MnO2 on the PEC signal of CdS, acceptable PEC performance of CdS, and the specific interaction between GSH and MnO2, the targets-triggered etching strategy exhibited excellent analytical performance for GSH detection with a detection limit of 0.05 mu mol/L and a linear range from 0.2 to 100 mu mol/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.