Design of magnetic metal-organic frameworks-molecularly imprinted polymer for extracting and microfluidic sensing of sulfamethoxazole

This study successfully designed and synthesized a novel magnetic molecularly imprinted composite material, Fe₃O₄@PCN-222@MIP, which integrates Fe₃O₄ nanoparticles, zirconium-based metal-organic framework (PCN-222), and molecularly imprinted polymer. This composite exhibits excellent magnetic responsiveness, high specific surface area, and characteristic recognition, enabling efficient enrichment and specific identification of sulfamethoxazole (SMX). The molecularly imprinted cavities provide complementary spatial structures and functional sites for SMX through hydrogen bonding and π–π interactions, achieving precise recognition. Notably, the composite also exhibits inherent peroxidase (POD)-like activity. Upon binding to SMX, electrons transfer from Fe to the sulfur atom in SMX, inhibiting its catalytic activity and reducing H₂O₂ decomposition efficiency, thereby establishing a direct colorimetric detection mechanism. We developed a microfluidic chip sensor integrating magnetic solid-phase extraction (MSPE) with colorimetric detection was developed. This method achieves a broad linear range (100–4200 nmol·L⁻¹) and low detection limit (632.74 nmol·L⁻¹) for SMX. When applied to complex food samples such as milk and honey, its recovery rates reaches 90%–110% without complex elution steps, demonstrating outstanding practicality and showing high consistency with high-performance liquid chromatography (HPLC). This study not only introduces innovative functional materials but also provides solutions for integrated, simplified equipment suitable for potential field applications.