Fluorescence detection of milk allergen β-lactoglobulin based on aptamers and WS₂ nanosheets

β-Lactoglobulin (β-Lg), a food allergen, can easily cause allergic reactions in infants and young children. Therefore, it is necessary to develop a rapid, sensitive, and selective detection method to protect individuals prone to allergies. In this paper, a fluorescence assay based on WS₂ nanosheets and a fluorescent dye (FAM)-labeled β-Lg aptamer was designed to detect β-Lg rapidly with high sensitivity. In the sensing platform, the β-Lg aptamer is adsorbed on the WS₂ nanosheet surface by van der Waals forces, which trigger the phenomenon of fluorescence resonance energy transfer (FRET) and suppress the fluorescence signal in the system. When β-Lg is present, the conformation of the aptamer specifically bound to β-Lg changes. Therefore, the aptamer is separated from the WS₂ nanosheet surface, and the fluorescence signal is recovered. This method combines the high quenching efficiency of WS₂ nanosheets and good specificity of the β-Lg aptamer. The detection range of this method for β-Lg is 0.1-100 μg mL^-1. The detection limit is 20.4 ng mL^-1. This method exhibits high sensitivity, selectivity and good reproducibility, and it can be used for β-Lg detection in actual samples.