Dual near-infrared AgInS2 and CuInS2 co-sensitized ZnO photoelectrode array enabled paper-based ratiometric photoelectrochemical aptasensing

Herein, a dual near-infrared (NIR)-response AgInS2 and CuInS2 co-sensitized ZnO photoelectrode array consisting of two spatial-resolved paper working electrodes (PWE1 and PWE2) was established to enable paper-based ratiometric photoelectrochemical (PEC) aptasensing of Di(2-ethylhexyl)phthalate (DEHP) based on triple-helix molecular switch (THMS)-mediated "on-off" switching of co-sensitization effect. Profiting from the co-sensitization of AgInS2 and CuInS2 on paper-based ZnO, the dual NIR-response cascade sensitization structure of AgInS2/CuInS2/ZnO exhibited a wide light response range and high charge separation efficiency, giving a "switch on" state of co-sensitization effect with markedly high photocurrent response. The "switch off" state of the co-sensitization effect was made by RecJf exonuclease-assisted target recycling-induced conformation change of THMS, which caused the detachment of AgInS2 quantum dots from the aptasensing interface, leading to a significantly decreased photocurrent signal. Accordingly, the constant I-1 of PWE1 and varying I-2 of PWE2 were collected based on the incubation of constant concentration of DEHP on PWE1 and various concentrations of DEHP on PWE2. The ultrasensitive detection of DEHP was realized by calculating the ratio of I-2/I-1. This work brought new insights into the establishment of a high-performance paper-based ratiometric PEC aptasensing platform for highly sensitive quantification of DEHP.