Enhanced photoelectrochemical sensing of T-2 toxin via photoelectron transfer mediated by SrTiO-CdInS/LaNiO composite and Mn-dependent DNAzyme amplification strategy.

T-2 toxin is widely distributed in cereal-based matrices and poses a potential risk to human health. Currently, most methods for detecting T-2 toxin are time-consuming and have low detection signals. Therefore, it is urgency to develop a method for rapid detection of T-2 toxin with high accuracy. This work presents a photoelectrochemical sensor for the rapid and sensitive detection of T-2 toxin based on signal quenching generated by the competition between SrTiO and CdInS/LaNiO, and a Mn-dependent DNAzyme assisted signal amplification strategy. The aptamer in the triple helix structure recognizes the T-2 toxin and releases a DNA probe. The DNA probe unlocks the DNAzyme, which combines Mn to turn to the cutting function, exposing the DNA sequence complementary to hairpin DNA2 (H2) on the substrate hairpin DNA1 (H1). The application of DNAzyme with Mndependence improves the accuracy and stability of the sensor. In addition, the integration of H2-SrTiO triggers a photonic competition with the substrate, and elicits steric hindrance for the adsorption of electron donor in the solution. This strategy effectively reduces the photoelectric conversion efficiency of heterojunction materials, leading to signal quenching. In this study, the concentration of T-2 toxin showed a broad linear relationship with the photocurrent signal in the range of 0.0001-50 ng mL, and the detection limit of the prepared sensor was as low as 0.021 pg mL. Furthermore, the versatility of this approach has been validated by its efficacy for the detection of actual samples, contributing to the field of photoelectrochemical biosensing.