▎ 摘　　要

A novel electrochemical aptasensor was constructed for ochratoxin A (OTA) detection based on Au octahedra and graphene (GR) as a signal amplification strategy. Au octahedra with eight triangle faces and sharp corners were prepared and acted as carriers to connect more thionine (Th) and complementary DNA (cDNA) to form Th-Au octahedra-cDNA. Th-Au octahedra-dsDNA was formed by hybridizing OTA aptamers with cDNA. GR with high surface area and good conductivity immobilized more biomolecules and facilitated electron transfer on the electrode surface. Th-Au octahedra-dsDNA was immobilized on the GR/GCE surface, producing a large initial peak current. In the presence of OTA, the formation of the aptamer-OTA complex induced the release of Th-Au octahedra-cDNA from the electrode surface and decreased the electrochemical signal of Th. The proposed aptasensor exhibited a wider linear range from 0.001 to 5 ng mL(-1) with a lower detection limit of 0.13 pg mL(-1); it also showed good selectivity against common interferences, including AFB1, ZEA and FB1.