Preparation of protein-resistant magnetic molecularly imprinted polymers as solid-phase extraction adsorbents via a one-stone-two-birds strategy for selective enrichment of tetracycline in milk

The widespread presence of antibiotic residues in animal-derived foods poses serious risks to public health and the environment, emphasizing the need for urgent action. This study presented a novel lightweight, popcorn-like magnetic molecularly imprinted polymer (LPR-MMIPs) with protein-resistant properties, for the selective enrichment of tetracycline (TC) antibiotics in milk. During the preparation of LPR-MMIPs, bovine serum albumin (BSA) was used as the functional monomer, and tris(2-carboxyethyl)phosphine (TCEP) served as the reducing agent. Using a “one-stone-two-birds” strategy, TCEP not only converted the α -helical structure of BSA to a β -folded conformation for imprinting on the Fe 3 O 4 carrier, but also etched the Fe 3 O 4 into a lightweight, popcorn-like structure under acidic conditions. The BSA imprinting layer excludes proteins through electrostatic repulsion, and the reduced amount of carrier material significantly enhances the adsorption efficiency ( Q  = 12.7 mg g −1 ), selectivity ( IF  = 3.02, SC  > 1.53), and reusability. Meanwhile, LPR-MMIPs, as solid-phase extraction adsorbents, have been successfully applied to the specific adsorption and separation of TC in real milk samples. The established method exhibits good accuracy, precision, and sensitivity, as evidenced by the low LOD (1.80 ng mL −1 ) and LOQ (5.60 ng mL −1 ), low RSDs (≤5.4 %), and high recovery rates (≥94.5 %). Besides, the method demonstrates excellent practical applicability for milk, offering a novel strategy for the selective enrichment of trace antibiotics in milk.