Metal–Organic\nFramework-Based Cascade Catalysis-Enabled\nFluorescent ELISA with Higher Enzymatic Stability for Zearalenone\nDetection in Maize

The enzyme-linked immunosorbent assay (ELISA) stands\nas one of\nthe most frequently employed rapid detection techniques for both chemical\nand biological contaminants. Horseradish peroxidase (HRP) and hydrogen\nperoxide (H<sub>2</sub>O<sub>2</sub>), serving as signal generators,\nplay indispensable roles throughout the entire ELISA process. However,\nHRP and H<sub>2</sub>O<sub>2</sub> exhibit high sensitivity to elevated\ntemperatures, hindering the broader utilization and transportation\nof ELISA. Hereby, being inspired by the cascade catalysis of glucose\nby glucose oxidase (GOx) and HRP as well as the advantageous properties\nof metal–organic frameworks (MOFs), we developed a cascade\ncatalysis-based competitive fluorescent ELISA (CCF-ELISA) for mycotoxin\ndetection in maize using zearalenone (ZEN) as a model. The results\nrevealed the remarkable protective effects of MOFs on enzymatic activities.\nBased on upon characteristics, the built CCF-ELISA enabled the detection\nof ZEN with a half-maximal inhibitory concentration of 0.54 ng/mL\nand allowed a detection range from 0.19 to 1.51 ng/mL. When applied\nto naturally contaminated maize samples, the outcomes obtained from\nthe CCF-ELISA showed a high level of comparability with high-performance\nliquid chromatography–tandem mass spectrometry, demonstrating\nthe promising potential of the developed CCF-ELISA in the rapid detection\nfor food security.