Preparation of a red-blood-cell-like surface molecularly imprinted polymer and its application to the selective enrichment of tetracycline in milk

<p id="p00010">The adsorption capacity per unit mass of a molecularly imprinted polymer is an important indicator for evaluating the adsorption performance of an imprinted material. Inspired by the large specific surface areas and excellent stabilities of double concave circular red-blood-cell discs, we synthesized a highly selective red-blood-cell-like surface molecularly imprinted polymer (RBC-SMIP) with a large adsorption capacity and a fast mass-transfer rate for tetracycline. This work used SiO₂ as the initial carrier and tetracycline, a broad-spectrum antibiotic, as the template molecule. Inexpensive and readily available dopamine functional monomers were subsequently coated on the surface of the SiO₂ carrier using surface molecular imprinting technology, after which the initial SiO₂ carrier was etched and removed using sacrificial-carrier-etching technology, with the dosage and coating time of the dopamine imprinting layer adjusted to regulate the morphology of the prepared imprinted material. An RBC-SMIP with a large specific surface area and excellent selective adsorption performance was finally prepared. Scanning electron microscopy (SEM) and infrared (FT-IR) spectroscopy, as well as N₂-adsorption-desorption, kinetics, thermodynamics, selectivity, and reusability experiments confirmed that the material had successfully been coated the imprinted polydopamine layer, and that the prepared material contained particles of uniform size and exhibited a good specific surface area and pore volume, a rapid adsorption-equilibrium time (15 min), and excellent reusability. The RBC-SMIP exhibited a unit-mass adsorption capacity and imprinting factor of 76.16 mg/g and 3.62, respectively. The successful preparation of the RBC-SMIP provides a new approach for the selective adsorption and determination of trace tetracycline contents in environmental water. In addition, combining the RBC-SMIP (as a solid-phase extractor) with HPLC led to a method with a high linear correlation coefficient (<italic>R</italic>²&gt;0.9995) in the 0.01-200 μg/mL linear range. Average recoveries of 92.1%-95.3% were determined at three spiked levels (0.01, 0.05, and 0.10 μg/mL), highlighting the ability of the method to efficiently adsorb, enrich, and detect tetracycline in milk samples. The red-blood-cell-like surface molecularly imprinted polymer developed in this work is expected to have significant practical applications.