Catalytic hairpin assembly integrated with multifunctional nanocomposites for colorimetric/photothermal/SERS detection of β-lactoglobulin

Accurate detection of β-lactoglobulin (β-Lg) in milk is crucial due to potential allergenic risks. This study presents an innovative trimodal sensing system. Firstly, a composite of ZnCo-MOF and spiky gold nanoparticles was synthesized. The ZnCo-MOF exhibits peroxidase-like activity and high loading capacity, while the spiky gold nanoparticles enhance photothermal and SERS properties. Secondly, the catalytic hairpin assembly (CHA) nucleic acid signal amplification strategy was employed, enabling sensitive detection. Through colorimetry, photothermal, and SERS modalities, mutual verification of signals was achieved. The sensor shows outstanding performance with low limits of detection (0.04-0.104 ng/mL) and excellent specificity. Satisfactory recovery rates in real food samples confirm its practicality, offering a novel and reliable solution for β-Lg detection. This pioneering work has opened up a new avenue for the safety quality control of special medical foods. It is expected to accurately identify the residues of β-Lg in raw materials and effectively safeguard the health of allergic individuals.