Pretreatment-Free Rapid Detection of Tiamulin in Egg and Milk Samples using Gold Nanoparticles Based on Positive List System Regulations

Tiamulin (TML) antibiotic residues in animal products could pose potential health hazards to consumers. South Korea set the positive list system regulations, where the maximum residue limits of TML in poultry eggs should not exceed 1000 ng/mL. Therefore, we developed a simple and pretreatment-free lateral flow immunoassay based on a highly specific TML antibody conjugated with gold nanoparticles for qualitative and semi-quantitative analysis of TML. The optimized sensor showed a visual limit of detection of 15 ng/mL for both milk- and egg-spiked samples, with a cut-off value of 100 ng/mL and 180 ng/mL for milk and egg, respectively. The assay demonstrated high recovery in both milk and egg matrices with relative standard deviation values below 12%, confirming its suitability for rapid and reliable determination of TML in complex food samples. As both sample types required no pretreatment and provided visible results within 10 minutes, the sensor is simple, user-friendly, and highly tolerant to matrix interferences. Moreover, it exhibited specific selectivity toward TML, supporting its potential as a promising detection platform for monitoring TML in animal products.