An electrochemical aptasensor based on PtPd NPs/g-C₃N₄ and a locked DNAzyme amplification strategy for ultrasensitive...

Adenosine triphosphate (ATP) is a widely recognized indicator of microbial contamination, and its rapid and accurate detection is essential for assessing microbial pollution in food safety. Herein, an electrochemical aptasensor integrating a dual-signal amplification strategy was developed for ultrasensitive detection of ATP. Platinum-palladium/graphitic carbon nitride (PtPd NPs/g-C₃N₄) was used as the electrode-modification material, improving the conductivity and electroactive surface area while providing a favorable platform for biomolecular immobilization. Additionally, an aptamer-regulated DNAzyme locking strategy was introduced for signal control, in which the DNAzyme was initially inactivated through hybridization with two aptamer sequences. Upon ATP binding, the aptamers undergo conformational changes and dissociate from the DNAzyme, thereby restoring its catalytic activity. The activated DNAzyme subsequently catalyzes the cyclic cleavage of substrate DNA strands on the electrode surface in the presence of Mg²⁺, leading to significant signal amplification. Under optimized conditions, the constructed aptasensor exhibited excellent analytical performance, with a linear range from 10 pM to 10 μM and a low detection limit of 1.71 fM. Moreover, the sensor demonstrated good selectivity, stability, and reproducibility, and was successfully applied to ATP detection in beer samples. This strategy provides a sensitive approach for trace ATP analysis and shows potential for applications in food safety analysis.