Detection of 13 quinolones in milk by a Pseudomonas quinolone signaling receptor-based competitive chemiluminescence assay.

With the widespread usage of quinolones (QN) in treating infectious diseases on farms, their notable toxicity and the emergence of resistance have raised increasing concerns in public health and environmental fields. Here, we report a competitive binding chemiluminescence assay (CLA) that enables the detection of 13 QN in milk. We deploy a specific binding biocomponent, the Pseudomonas quinolone signaling receptor (PqsR), to facilitate sensitivity and group-specificity toward QN. Through structural alignment, molecular docking, and surface plasmon resonance method, we elucidate the mechanism of molecular interaction and the high affinity between PqsR and QN. The PqsR-based CLA demonstrates an ultralow limit of detection for 13 QN ranging from 1.91 × 10-3 to 6.18 × 10-2 ng·mL-1, which complies with the maximum residue limit of QN established in China, the European Union, and the United States. Furthermore, it illustrates spiked recoveries in milk matrices ranging from 70.2% to 97.3%, with coefficients of variation below 12.8%. These findings highlight the potential of the PqsR-based CLA for high-throughput, rapid, and sensitive detection of multi-QN. Exploring the commonality of interactions qualitatively and quantitatively from a structural perspective may pave the way for the discovery of novel group-specific binding materials.