An electrochemical aptasensor based on dual-enzymes-driven target recycling strategy for patulin detection in apple juice

The presence of patulin (PAT) in fruits poses a threat to human health. Herein, a dual-enzymes-driven target recycling (dual-EATR) strategy-based PAT electrochemical aptasensor was constructed. The branched structure of the labeling material silver-palladium nanoparticles (AgPdNPs) can effectively load thionine (Thi). Gold nanoparticles (AuNPs)/Fe metal-organic frameworks (FeMOF)-PEI-GO with effective catalytic activity can amplify the redox signal of Thi. The presence of PAT could trigger the dual target recycling assisted by Exonuclease III and Mg2+-dependent DNAzyme. The dual-EATR strategy gradually accumulates detection sig-nals and can realize ultra-sensitive detection of PAT. With the optimal conditions, the developed aptasensor showed satisfactory performance with the range from 5 x 10(-7) ng mL(-1) to 5 ng mL(-1) and a low detection limit of 0.217 fg mL-1. Compared with the chromatographic method, the developed aptasensor has consistent detection results. In addition, the aptasensor exhibited favourable selectivity, reproducibility and long-term stability. In the analysis of real samples, the aptasensor had good accuracy (recovery%, 91.0-103) and high precision (RSD%, 2.69-4.98), and relative error of < 13% compared with the spiked concentration. It is proved with 95% of confidence level that the spiked sample tested generated a signal response not significantly different from the true value (p > 0.6). The feasibility of the aptasensor in apple juice samples has been verified, providing an excellent choice for the detection of trace PAT.

Automated summary

In this study, a dual-enzymes-driven electrochemical aptasensor was constructed for ultra-sensitive detection of patulin (PAT) in fruits. The aptasensor showed favorable selectivity, reproducibility, and long-term stability. In real sample analysis, the aptasensor demonstrated good accuracy and precision.