Homogeneous fluorescence immunoassay based on AuNPs quenching dendritic silica assembled with multicolor QDs for the simultaneous determination of four mycotoxins in cereals

In this work, a novel homogeneous fluorescence immunoassay for the simultaneous detection of ochratoxin A (OTA), aflatoxin B1 (AFB1), fumonisins B1 (FB1), and zearalenone (ZEN) in cereal samples is established. Here, amino groups and thiol groups are grafted onto the surface of dendritic mesoporous silica nanoparticles (DMSNs) to improve loading rate and fluorescence preservation rate of quantum dots (QDs), enabling enrichment and amplification of fluorescence signals. In this test system, the fluorescence of the signal probe (DMSNs@QDs@Ab) is quenched by AuNPs, and then the presence of the targets makes the fluorescence of the signal probes recover. The correlation between the recovered fluorescence value and mycotoxin concentration is applied to achieve quantitative detecting mycotoxins. This assay displays good linear correlation in range of 0.01–100 μg L-1, with the limit of detection (LOD) of 0.0001 μg L-1 for OTA, 0.0008 μg L-1 for AFB1, 0.001 μg L-1 for FB1, and 0.0006 μg L-1 for ZEN, respectively. The proposed assay is applied to detect multiple mycotoxins in contaminated cereal samples and the test results is confirmed by liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Avail of silica with high loading capacity for assembling multicolor QDs to achieve simultaneous multi-signal output, a simple and efficient homogeneous fluorescence immunoassay is proposed for the first time. This multiplex test strategy provides a good idea for simultaneous, rapid, and sensitive detection of multiple hazardous substances in food and environment samples.