Multiplexed fluorescence immunoassay combined with magnetic separation using upconversion nanoparticles as multicolor labels for the simultaneous detection of tyramine and histamine in food samples

We have developed an upconversion nanoparticles (UCNPs) based fluorescence immunoassay for simultaneously detecting tyramine and histamine in foods. The anti-tyramine and anti-histamine antibody were linked to NaYF4Yb, Tm (emission at 483 nm) and NaYF4Yb, Er (emission at 550 nm) UCNPs as multicolor signal probe, respectively. The tyramine and histamine coating antigen were connected to magnetic microspheres as capture probe, respectively. Base on a competitive format, capture probes compete with analytes to combine corresponding signal probes. Under excitation at 980 nm, the formed competitive immune-complex fluorescent signal at 483 and 550 nm indicates concentration of tyramine and histamine, respectively. This immunoassay has detection linear from 0.5 to 100 μg L−1 with limit of detection (LOD) of 0.1 μg L−1 for tyramine, and 0.1–100 μg L−1 with LOD of 0.01 μg L−1 for histamine, respectively. This multiplexed analysis format has potential applications for rapid, efficient detecting multiple food risk factors.