Rapid and Sensitive Fluoroimmunoassay Based on Quantum Dots for Detection of Melamine in Milk

Abstract

A rapid and sensitive indirect competitive fluorescence-linked immunosorbent assay (icFLISA) method was developed for detection of melamine in milk based on secondary antibody (Ab2)-conjugated quantum dots (QDs). The sensitivity of icFLISA with a limit of detection (LOD) of melamine (3.88 ng mL−1) and 50% inhibition value (IC50) (31.58 ng mL−1), was much higher than that of icELISA. As a proof of principle, recovery tests involving four fortification levels (150, 80, 40, and 20 ngmL−1) in blank samples were also performed. The recoveries ranged from 80.85 to 110.54% with coefficient of variations (CVs) of 2.82–8.82%. When challenged with authentic samples, these results of icFLISA were consistent with that of icELISA, immuno-chromatographic assay and gas chromatography-single quadruple mass spectrometry (GC-MS)method, indicating that icFLISA can be considered as a new screening method for detection of melamine in milk.