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

Abstract

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 (Fe₃O₄@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 Fe₃O₄@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.

Keywords: Aptamer; Food allergy; Infant food formula; Nonspecific protein adsorption; Sandwich assay.