Development of a H2O2-sensitive quantum dots-based fluorescent sandwich ELISA for sensitive detection of bovine β-lactoglobulin by monoclonal antibody

BACKGROUND Bovine β-lactoglobulin (BLG) is the major allergen in cows’ milk, and specific epitope play a key role in food allergy. Developing a method specifically bind to IgE epitope is necessary for testing BLG and its allergenic residues. RESULTS The monoclonal antibody (1G9) specific to IgE linear epitope for BLG was identified as high affinity and specificity. Based on 1G9, a sensitive fluorescent sandwich enzyme-linked immunosorbent assay (sELISA) was successfully developed using catalase-mediated fluorescence quenching of thiolated CdTe quantum dots in the presence of hydrogen peroxide as fluorescent signal output. The fluorescent sELISA showed high sensitivity and specificity, the limit of detection was 0.49 ng mL−1, which was 16-folds lower than horseradish peroxidase (HRP)-based sELISA. The linear range for BLG detection were 125–4000 ng mL−1 (r2 = 0.9939) and 0.48–62.5 ng mL−1 (r2 = 0.9919). The recoveries and coefficients of variation were 94.25%–109.83% and 4.38%–20.29%, respectively. Allergenic residues were also detected in hydrolyzed infant formulas. The results of fluorescent sELISA showed good performance as HRP-based sELISA and commercial sELISA kit. CONCLUSION This proposed fluorescent sELISA could be employed to detect BLG and its allergenic residues in food with highly sensitivity, reliability, and recovery.