Ultrasensitive detection of patulin based on a Ag⁺-driven one-step dual signal amplification

Due to improper storage, the presence of patulin in fruits poses a threat to food safety. Herein, a one-step dual amplification strategy-based electrochemical aptasensor was proposed for patulin detection. Silver-palladium nanoparticles (AgPdNPs) with a hollow and branched structure were used as a supporting material for thionine to provide numerous attachment sites. AuNFs/g-C₃N₄ was employed as an electrode modification material, which has been demonstrated to facilitate electron transport and improve signal label loading capacity. Ag⁺ ions were released in the presence of patulin, activating the Ag⁺-DNAzyme on the electrode surface. The formed Ag⁺-DNAzymes further cyclically cleaved the substrate DNA, and the released sequences were used as a new trigger to mediate the secondary recirculation. This one-step dual amplification strategy enabled double target recycling without additional procedures. The signal cascade amplification through dual target recycling, was thus available for trace detection of patulin. Under the optimal conditions, the electrochemical aptasensor achieved a satisfactory linear range from 5.0 × 10^-6 μg L^-1 to 50 μg L^-1 with a detection limit of 0.92 fg·mL^-1 for the determination of patulin. In addition, the aptasensor exhibited favorable selectivity, reproducibility, repeatability and long-term stability, and thus can be employed for patulin detection in apple juice samples, providing excellent choice for the detection of trace patulin.