Smartphone-integrated fluorescent quenching immunochromatographic test strips designed for the determination of sesame allergens in food samples

Abstract

A highly sensitive smartphone-integrated fluorescence quenching immunochromatographic assay (FQICA) for the detection of sesame allergen was proposed. Sesame antibodies were adsorbed on the surface of the gold nanoparticles to form fluorescent acceptors (AuNPs-Ab). Ovalbumin (OVA) protein was labeled with quantum dots (QDs) to form signal probes (QDs-OVA), which were coated on the C-line of the assay strips. A mixture of QDs-OVA and sesame protein was coated on the T-line of the strip. For FQICA, the concentration of the analyte was positively correlated with the fluorescence signal. The developed FQICA had high sensitivity for the detection of sesame protein, and its visual LOD was 80 μg/L and the quantitative LOD was 40 μg/L. In addition, the method had high specificity, except for a small cross-reaction between sesame and walnut. The visual LODs in bread, ham, and biscuits were 640 μg/L. The quantitative LODs were 320 μg/L for biscuits and 640 μg/L for bread and ham. Comparing the developed FQICA with a commercial ELISA kit, the recoveries of sesame protein in both methods were between 80% and 120%.