Design and controlled synthesis of molecularly imprinted fluorescence sensor supported by multifunctional magnetic covalent organic framework: Efficient detection of clofibric acid in the environment

Abstract

While some studies have explored magnetic covalent organic frameworks (MCOFs) for fluorescence sensing, substantial research gaps remain, especially in integrating molecular imprinting technology (MIT). In this study, superparamagnetic Fe3O4 cores were modified, and a monomer-mediated in situ growth strategy was used to synthesize uniform, multifunctional MCOFs nanoparticles. Subsequently, molecularly imprinted polymers (MIPs) were synthesized via a sol-gel method and deposited on MCOFs, forming MCOFs-supported molecularly imprinted fluorescent sensors (MCOFs@MIPs) for trace analysis of clofibric acid (CLF). This was the first application of molecularly imprinted fluorescence sensing technology for detecting CLF. MCOFs@MIPs combined the superparamagnetism of Fe3O4, the stability and signal amplification of COFs, and the selectivity of MIPs for CLF. Studies demonstrated that MCOFs@MIPs had a maximum fluorescence response in isopropanol, with an optimal dosage of 0.39 mg/mL, an imprinting factor (IF) of 2.73, a detection limit of 94 nM, and a range of 0 ∼ 300 µM. Characterizations revealed that the fluorescence quenching of MCOFs@MIPs was based on a photoinduced electron transfer (PET) mechanism, with MCOFs@MIPs as donors and CLF as acceptors. MCOFs@MIPs were used to detect CLF in actual samples from food, water, agricultural products, cosmetics, and human metabolites. The detection results were consistent with those from high-performance liquid chromatography (HPLC). Additionally, the recoveries of MCOFs@MIPs for actual samples ranged from 94.4 % to 100.7 %, demonstrating exceptional reliability, reusability, and accuracy.