Sandwich assay for β-lactoglobulin in infant food formula based on a hierarchically architectured antifouling capture probe and fluorescent recognition probe.

Tracing the presence of allergenic β-lactoglobulin (β-Lg) in infant foods is an urgent need, but the interference from the protein-rich matrix often hampered the detection accuracy. Here, we developed a sandwich assay for β-Lg in infant food formula based on a hierarchically architectured antifouling capture probe and fluorescent recognition probe. The antifouling capture probe was constructed from the polydopamine-coated magnetic particles (FeO@PDA), which was modified with repeated glutamic acid-lysine (EK) antifouling peptide and aptamer towards β-Lg. The spatial arrangement of these ligands on the FeO@PDA surface was carefully tailored. Furthermore, a fluorescent recognition probe based on aptamer-modified silica-doped carbon quantum dot was developed to explore a sandwich assay for β-Lg with the capture probe. The sandwich assay was proved to have high potential in detecting β-Lg in commercially available infant food samples. The work provided a new approach to developing detection methods with matrix interference-resistant properties.