Photoelectrochemical Sensors with Near-Infrared-Responsive Reduced Graphene Oxide and MoS for Quantification of O157:H7.

The photoelectric response is crucial for photocatalysis, having applications in solar cells and photoelectrochemical (PEC) sensors. In this study, we demonstrate improvements in the near-infrared (NIR)-light-driven PEC response via synergism between reduced graphene oxide (rGO) and MoS. Intriguingly, rGO modulates the morphology of MoS, facilitating carrier generation and migration, improving the PEC performance of the resultant rGO-MoS sheets (GMS), and yielding an approximately 8-fold increase in the photocurrent compared to that of the pure MoS. Based on these findings, a NIR-responsive PEC immunosensing platform for the "turn-on" analysis of O157:H7 on 980 nm light irradiation is reported. Specifically, the device is a three-dimensional magnetic screen-printed paper-based electrode assembled on a home-made PEC cell, and it enables integrated separation and detection. Using a sandwich-type immunocomplex bridged by O157:H7 and a GMS PEC probe, the immunosensing platform detected O157:H7 between 5.0 and 5.0 × 10 CFU mL, having an extremely low detection limit of 2.0 CFU mL. Further, the assay enables the direct analysis of O157:H7 in milk without the need for pretreatment. Our findings suggest directions for the development of NIR-responsive paper-based PEC materials for portable biomolecule sensing.