Photoelectrochemical Sensors with Near-Infrared-Responsive Reduced Graphene Oxide and MoS 2 for Quantification of Escherichia Coli 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 2 . Intriguingly, rGO modulates the morphology of MoS 2 , facilitating carrier generation and migration, improving the PEC performance of the resultant rGO-MoS 2 sheets (GMS), and yielding an approximately 8-fold increase in the photocurrent compared to that of the pure MoS 2 . Based on these findings, a NIR-responsive PEC immunosensing platform for the "turn-on" analysis of Escherichia coli 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 E. coli O157:H7 and a GMS PEC probe, the immunosensing platform detected E. coli O157:H7 between 5.0 and 5.0 × 10 6 CFU mL -1 , having an extremely low detection limit of 2.0 CFU mL -1 . Further, the assay enables the direct analysis of E. coli 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.