Au/Ir@Zn/Cu-MOF-based lateral flow immunoassay employing high-affinity monoclonal antibody for sulfamethoxazole detection

Sulfamethoxazole (SMX) is a widely used sulfonamide antibiotic, and its residues in animal-derived foods pose significant health risks. In this study, a high-affinity monoclonal antibody (2.65 × 10 10 L/mol) against SMX was developed and used to construct an Au/Ir@Zn/Cu-MOF-based lateral flow immunoassay (LFIA). The probe was thoroughly characterized with good stability. The LFIA achieved a visual detection limit of 2.5 μg/mL, with an IC 50 of 565.84 ng/mL and a linear detection range of 6.8 ng/mL-47.06 μg/mL. No cross-reactivity to structural analogues or matrix interference was observed in real food samples. Recovery rates (97.92–108%) were consistent with LC-MS results, confirming the accuracy of the method. This LFIA provides a sensitive and reliable tool for rapid SMX screening in food products. • High-affinity anti-SMX monoclonal antibody (2.65 × 10 10 L/mol). • Au/Ir@Zn/Cu-MOF-based LFIA: LOD 6.8 ng/mL; IC 50 of 565.84 ng/mL. • High specificity with minimal matrix effects; 94.37–106.32% recoveries (LC-MS-verified).