Core-satellite-structured magnetic nanozyme enables the ultrasensitive colorimetric detection of multiple drug residues on lateral flow immunoassay.

Background: Excessive use of veterinary drugs causes severely environmental pollution and agricultural pollution, and poses great threat to human health. A simple method for the rapid, highly sensitive, and on-site monitoring of veterinary drug residues in complex samples remains lacking.

Results: In this study, we propose a catalytically enhanced colorimetric lateral flow immunoassay (LFA) based on a novel core-satellite-structured magnetic nanozyme (Fe-Au@Pt) that can simultaneously and quantitatively detect three common veterinary drugs, namely, gentamicin (GM), streptomycin (STR), and clenbuterol (CLE), within a short testing time (<30 min). The Fe-Au@Pt nanozyme was simply prepared through the self-assembly of numerous Au@Pt nanoparticles on a large FeO core via electrostatic adhesion, which exhibited the advantages of high peroxidase-like activity, strong magnetic responsiveness, and multiple catalytic sites. Under the dual-signal amplification effect of magnetic enrichment and catalytic enhancement, the proposed nanozyme-LFA allowed the multiplex detection of STR, CLE, and GM with detection limits of 10.1, 6.3, and 1.1 pg/mL, respectively.

Significance: The developed Fe-Au@Pt-LFA achieves direct, simultaneous, and accurate detection of three target drugs in food samples (honey, milk, and pork). The proposed assay shows great potential for application in the real-time monitoring of small-molecule pollutants in complex environment.