Multiple recognition-powered abiotic bimetallic oxide nanozyme-based colorimetric platform for the selective detection of allergen β-lactoglobulin.

β-lactoglobulin (β-lg) is the major allergen in dairy products, and poses a significant threat to special people including infants and young children. Therefore, a convenient, cost-efficient, and aptamer-free colorimetric sensing platform is developed for β-lg assay based on a germanium/zinc bimetallic oxide nanozyme (GeO/ZnO). The CTAB-assisted intercalation growth of ZnO nanoparticles between GeO layers endows GeO/ZnO with enhanced peroxidase-mimicking activity and β-lg affinity. By virtue of multiple recognition-meditated specific protein corona formation, the catalytic activity of GeO/ZnO is greatly deteriorated in the presence of β-lg. The selective discrimination and accurate detection of β-lg in dairy samples is achieved with a detection limit of 14.1 nM, and a portable kit is further established for point-of-care testing and visual colorimetric analysis. This study not only provides a promising strategy for allergen assay, but paves an avenue for engineering the abiotic protein affinity sensors for food safety analysis.