Fluorescence ELISA based on CAT-regulated fluorescence quenching of CdTe QDs for sensitive detection of FB₁

A competitive fluorescence enzyme-linked immunosorbent assay (cFELISA) was developed for the highly sensitive detection of fumonisin B₁ (FB₁) based on the catalase (CAT)-regulated fluorescence quenching of mercaptopropionic acid-modified CdTe quantum dots (MPA-QDs). We propose a system that uses an FB₁-labeled CAT (FB₁–CAT) as a competing antigen for hydrogen peroxide (H₂O₂) decomposition, and H₂O₂-sensitive MPA-QDs were adopted provided the signal output of the cFELISA. Various parameters that could influence the sensitivity of cFELISA, including the labeled molar ratio of FB₁ to CAT in FB₁–CAT, concentration of the anti-FB₁ monoclonal antibodies and FB₁–CAT, hydrolysis time of CAT to H₂O₂, and the pH and methanol concentration in the sample solution, were optimized. The developed cFELISA exhibits a favorable dynamic linear quantitative detection of FB₁ over the range of 0.39–12.50 ng mL⁻¹ under the optimized detection conditions. The half maximal inhibitory concentration and limit of detection were 1.95 and 0.33 ng mL⁻¹, respectively, which were approximately 10- and 15-fold lower than those of a horseradish peroxidase-based colorimetric ELISA. The recovery of intra- and inter-assays for FB₁-spiked corn samples ranged from 80.9% to 87.7% and 85.8% to 93.1%, with a coefficient of variation ranging from 5.5% to 8.6% and 11.5% to 17.4%, respectively. Moreover, the proposed cFELISA exhibited negligible cross-reaction with other common mycotoxins. The reliability of the proposed method was further confirmed by ultra-performance liquid chromatography with fluorescence detection. The proposed method displays remarkable potential for the rapid, sensitive, and cost-effective detection of mycotoxins or analytes with applications in food quality control and safety monitoring.