Synthesis of molecularly imprinted polymers via core-shell magnetic mesoporous silicon-metal organic frameworks and their detection of three estrogens in traditional Chinese medicinal materials.

Steroidal estrogens are a type of compound that disrupts endocrine function and could potentially threaten food safety and human health. So, there is a real need for a sensitive and convenient method to detect estrogens in food samples. Magnetic silica (Fe3O4@SiO2) has been recognized as a versatile adsorbent material with a porous structure that provides numerous imprinting sites while reducing mass transfer resistance, making it a promising candidate for adsorption applications. Fe3O4@SiO2 denotes core-shell nanoparticles with magnetite as core and silica as outer shell. However, to further enhance the adsorption capacity and selectivity, the incorporation of metal-organic frameworks (MOFs) can be highly beneficial. In this work, estrogens were detected using molecularly imprinted polymers (MIPs) based on composites of Fe3O4@SiO2 and aluminum metal-organic framework (Al-MOF). The Al-MOF, specifically MIL-68(Al), was selected for its high surface area, tunable pore size, and strong stability, which contribute to its excellent adsorption properties. The incorporation of MIL-68(Al) into the Fe3O4@SiO2 matrix not only increases the available surface area but also provides additional specific binding sites for estrogens, resulting in enhanced selectivity and sensitivity. The resulting Fe3O4@SiO2@MIL-68(Al)@MIP material proved to be a powerful adsorbent for estrogens with a maximum adsorption capacity of 34.52 mg g-1. Notably, Fe3O4@SiO2@MIL-68(Al)@MIP exhibited high adsorption capacity and selectivity and achieved a limit of detection (LOD) of 1.1-4.6 ng mL-1 (0.04-0.18 µg kg-1) and a linear response range of 40.96-8000 ng mL-1, with recoveries between 87.34% and 99.86%, and relative standard deviations (RSDs) ≤ 5.92%. These impressive results are attributed to the synergistic effect of the magnetic core, porous silica shell, and high-affinity MOF, making the material a highly efficient sorbent for the pretreatment of estrogenic veterinary drugs in traditional Chinese medicine.