An electrochemical aptasensor for zearalenone detection based on the Co₃O₄/MoS₂/Au nanocomposites and hybrid chain reaction

An electrochemical aptasensor was used for the fast and sensitive detection of zearalenone (ZEN) based on the combination of Co₃O₄/MoS₂/Au nanocomposites and the hybrid chain reaction (HCR). The glassy carbon electrode was coated with Co₃O₄/MoS₂/Au nanomaterials to immobilize the ZEN-cDNA that had been bound with ZEN-Apt by the principle of base complementary pairing. In the absence of ZEN, the HCR could not be triggered because the ZEN-cDNA could not be exposed. After ZEN was added to the surface of the electrode, a complex structure was produced on the modified electrode by the combination of ZEN and ZEN-Apt. Therefore, the ZEN-cDNA can raise the HCR to produce the long-strand dsDNA structure. Due to the formation of dsDNA, the methylene blue (MB) could be inserted into the superstructure of branched DNA and the peak currents of the MB redox signal dramatically increased. So the concentration of ZEN could be detected by the change of signal intensity. Under optimized conditions, the developed electrochemical biosensing strategy showed an outstanding linear detection range of 1.0×10⁻¹⁰ mol/L to 1.0×10⁻⁶ mol/L, a low detection limit (LOD) of 8.5×10⁻¹¹ mol/L with desirable selectivity and stability. Therefore, the fabricated platform possessed a great application potential in fields of food safety, medical detection, and drug analysis.