Silver-mediated electrochemical sensor for rapid determination of hypochlorite in the coexistence of ROS

An electrochemical sensor (ITO-AuNPs-cys-Ag) for the determination of hypochorite (ClO^-) was constructed, where Au nanoparticles (AuNPs) serve as the substrate and Ag⁺ acts as the signal probe, interconnected via cysteamine (cys) through Au-S and Ag-N bonds. The disruption of the Ag-N coordination bond by ClO^- causes the detachment of Ag⁺ from the sensing interface, resulting in a decrease in the electrochemical signal. A wide linear range of 0.75-25 μM and a low limit of detection (LOD) of 0.53 μM were obtained with the sensor. The used sensor can be regenerated by incubation in a AgNO₃ solution. Further study revealed that Ag⁺ plays a critical role in preventing the interferences from other highly oxidative reactive oxygen species (ROS) in samples; thus, the prepared sensor can be directly applied to the determination of ClO^- in environment samples and ferroptosis of NIH3T3 cells. The results obtained not only provide a useful sensor for exploration of the reaction processes and physiological pathways of ClO^-, but also demonstrate a new strategy to improve the selectivity of electrochemical sensors.