Fluorescence signal "turn-on" lateral flow immunoassay based on fluorescent MOF and black FePNs for highly sensitive naked-eye detection of deoxynivalenol.

To meet the need for sensitive and visual on-site detection of deoxynivalenol (DON), a fluorescence signal "turn-on" lateral flow assay (FONLFA) was developed. The fluorescent nanocomposites, zirconium-based metal-organic frameworks (ZrMOFs), were synthesized by using an aggregation-induced emission luminogen (AIEgen) as ligand. The ZrMOFs and the antigen, deoxynivalenol-bovine serum albumin (DON-BSA), could be conveniently immobilized on the test line (T-line) through simple mixing and spraying. And Fe-polydopamine nanoparticles (FePNs) immunoprobes were utilized as both colorimetric signal elements and fluorescence quenchers. Fluorescence signal was generated through the competitive binding between DON and the immobilized antigen. As a result, the constructed FONLFA method achieved the visual limit of detection (vLOD) of 1.0 ng/mL, which demonstrated 20-fold improvement over conventional colorimetric LFA method. The quantitative detection achieved the linear range of 0.25-5.0 ng/mL with the LOD of 0.10 ng/mL. The assay showed good recoveries, ranging from 96.8% to 103.5% in corn samples. These results demonstrate that the developed FONLFA offers high practical potential for rapid DON screening in food samples.