Naked-eye readout colorimetric signal-based assays are promising for high-throughput screening detection and point-of-care diagnostics in resource-constrained regions. Here, a novel direct competitive plasmonic enzyme-linked immunosorbent assay (dc-pELISA) based on gold nanoparticle (AuNP) aggregation with highly sensitive and robust naked-eye readout signal was developed and used to detect fumonisin B1 (FB1). AuNP aggregation was induced by a horseradish peroxidase (HRP)/hydrogen peroxide (H2O2)/tyramine (TYR) system, resulting in a dramatic color change from red to blue. In this system, H2O2 was produced via GOx-mediated glucose oxidation reaction, and FB1-GOx was used as a competitive antigen. The proposed pELISA demonstrated good linear detection of FB1 from 3.125 ng mL-1 to 25 ng mL-1 with a vivid color change from deep blue to red and a cutoff limit of 12.5 ng mL-1 observed by the naked eye. The average recoveries for FB1-spiked corn samples ranged from 76.5% to 96.8% with a relative standard derivation of 4.88~ 16.4%. Meanwhile, the proposed method exhibited excellent agreement (R2 = 0.927) with the conventional ELISA method in blindly detecting FB1 spiked corn samples. Additionally, the results of the proposed method for FB1 positive corn samples also showed a high consistency with those of the ultra performance liquid chromatography method. These results indicated acceptable accuracy and precision of the proposed colorimetric ELISA for quantitative detection of FB1 in actual corn samples.
Keywords: Fumonisin B(1); Glucose oxidase; Gold nanoparticle aggregation; Plasmonic ELISA; Tyramine.
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