A Photoelectrochemical Biosensor Based on a Composite Structure of Au Nanoparticles Loaded on NiO/TiO2 Heterojunction for Sensitive Analysis of Cold-Resistant RNA in Winter Wheat

Materials with heterostructures that are sensitive to light have a wide range of applications in photoelectrochemical (PEC) detection and can improve their photoelectric performance. Here, we have designed a reliable and low-cost PEC biosensor applied for the detection and analysis of cold-resistant RNA in winter wheat. First, TiO2 nanospheres, a photoactive material, as well as NiO nanoflowers were prepared, and TiO2 was coupled with prepared NiO to form a compact heterojunction structure of NiO/TiO2, on which Au nanoparticles were loaded and used to modify the surface of the ITO conductive glass, resulting in the preparation of Au/NiO/TiO2/ITO electrodes. Then, single-stranded RNA (ssRNA) was immobilized as a probe on top of the electrode. The two would bind specifically when the target ssRNA concentration was added, and then, the sensing performance was analyzed using a series of characterization and PEC tests. The results demonstrated that the photocurrent signal response was correlated with the target RNA (tRNA) concentration, and the sensor showed a low limit of detection (LOD =0.015 pM) and a correlation coefficient of 0.99576 over a wide linear range of concentrations from 1 pM to 100 nM. The prepared biosensors showed good reproducibility, stability, and excellent specificity. The proposed Au/NiO/TiO2 composite can effectively measure the cold-resistant RNA levels in winter wheat, which provides a value for grain yield and cold-resistant breeding.