Highly sensitive simultaneous lateral flow assay for the detection of mycotoxins based on multichromatic metal-organic framework encapsulated fluorescent metal nanoclusters.

Multichromatic fluorescent nanomaterials-based multiplexed lateral flow immunoassays (mLFAs) enable the rapid and accurate simultaneous detection of multiple mycotoxins, which is essential for food quality monitoring. In this study, we exploited the preparation method for multichromatic metal-organic framework (MOF) encapsulated fluorescent metal nanoclusters (MNCs) and obtained two bright nanocomposites (Sc3+-AuNCs@ZIF-8 and Y3+-AuNCs@ZIF-8). And we developed a multichromatic fluorescent mLFA (MFLFA) for simultaneous detection of aflatoxin B1 (AFB1) and ochratoxin A (OTA). Benefiting from rare earth metal ions (Sc3+/Y3+) coordination and zeolitic imidazolate framework-8 (ZIF-8) encapsulation, the gold nanoclusters (AuNCs) exhibited synergistically enhanced fluorescence via the restriction of intramolecular motion (RIM), and achieved significantly improved stability. The prepared green-emitting Sc3+-AuNCs@ZIF-8/antibody (Ab) and red-emitting Y3+-AuNCs@ZIF-8/Ab were employed as specific immunoprobes to develop an MFLFA. The limits of detection (LODs) of 1.8 pg/mL (AFB1) and 0.014 ng/mL (OTA), which were 5-fold and 17.2-fold lower than those of the conventional AuNPs-based mLFA, respectively.