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.