Aptamer-functionalized PVA/AG hydrogel for enrofloxacin detection in milk with simplified sample pretreatment

To tackle the technical bottlenecks in detecting enrofloxacin (ENR) residues in milk matrices, which include complex operations, lengthy procedures, and significant matrix interference, this study constructed a fluorescent detection system based on split aptamer-functionalized polyvinyl alcohol/agarose (PVA/AG) double-network hydrogels, integrating molecular recognition, matrix purification, and signal response functions. Through a physical cross-linking strategy, complexes loaded with PCN-224-Apt1 and gold nanorods (Au NRs)-Apt2 were in-situ embedded into the PVA/AG three-dimensional (3D) network. This method exploits the macromolecular exclusion effect of hydrogels and the highly specific recognition property of split aptamers, enabling rapid enrichment and matrix interference elimination of ENR in milk within 15 min. Sensitive detection of ENR is achieved in the concentration range of 0.01-1 ng/mL, with a limit of detection (LOD) down to 0.003 ng/mL. This research provides a novel strategy for the on-site, rapid, and sensitive detection of small-molecule contaminants in milk matrices.