An electrochemical aptasensor based on tetrahedral DNA nanostructures as a signal probe carrier platform for sensitive detection of patulin.

In this work, we proposed an electrochemical aptasensor for patulin (PAT) based on tetrahedral DNA nanostructures (TDNs) and thionine (Thi)-labeled Fe3O4 nanoparticles (Fe3O4NPs)/rGO signal amplification strategy. The rigid structure of TDNs could effectively improve the binding efficiency. Fe3O4NPs/rGO with excellent electrical conductivity and large specific surface area was used as a label material, which could load more Thi and accelerate electron transfer. Besides, the unique catalytic properties of Fe3O4NPs could achieve active signal amplification. Once PAT existed, PAT aptamer was released from the capture probe, thereby introducing Fe3O4NPs/rGO with Thi onto the electrode surface. Therefore, a noticeable increase in Thi current intensity was observed. Under the optimized conditions, the proposed aptasensor showed superior performance with a linear range from 5 × 10-8 to 5 × 10-1 μg mL-1 and a detection limit of 30.4 fg mL-1. The obtained sensor showed reliable specificity, stability and reproducibility, and was successfully applied to the determination of real samples.