A electrochemical aptasensor based on cross-linked DNA framework and Au@ZnCoN-C nanomaterials for ciprofloxacin detection

The widespread misuse of ciprofloxacin (CIP) poses a serious threat to environmental safety and human health, necessitating its trace detection in food matrices. In this study, a novel electrochemical aptasensor was developed for the highly sensitive detection of CIP. Au@ZnCoN-C nanocomposites with superior conductivity were synthesized and employed as the electrode modification material. To improve assay sensitivity, a target-triggered cyclic amplification method relying on RecJf exonuclease was adopted. Notably, a cross-linked DNA framework (CLDF) was utilized for the first time in CIP detection. Its interconnected architecture provides abundant active sites for high-density loading of methylene blue (MB), thereby significantly amplifying the electrochemical response. Under optimized conditions, the aptasensor exhibited a wide linear range from 0.005 to 1000   ng/mL, with a low limit of detection (LOD) of 3.2   pg/mL. Furthermore, the sensor was successfully applied to the analysis of CIP in milk, egg, and pork samples with satisfactory results. Leveraging its high specificity, long-term stability, and high sensitivity, this method provides a robust strategy for the precise monitoring of CIP in food safety applications.