Eu-MOF-based sandwich-type magnetic molecularly imprinted fluorescent sensor for sensitive and visual detection of chlorogenic acid in cigar tobacco

A sandwich-type magnetic molecularly imprinted fluorescent sensor (BA-Eu-MOF-CGA-MIPs) based on europium-based metal-organic frameworks (Eu-MOF) was constructed for highly selective detection of chlorogenic acid (CGA) in cigar tobacco and its products. The sensor integrates magnetic separation (via Fe₃O₄ nanoparticles), imprinted cavities for specific capture, and boronate-affinity-mediated sandwich structure for fluorescence quenching. Under optimal conditions, a detection limit of 0.96 µg/mL and a linear range of 21.3-173 µg/mL were achieved. The sensor exhibits excellent selectivity over structural analogs and enables smartphone-assisted visual semi-quantitative detection. Satisfactory recoveries ranging from 93.74% to 104.07% were obtained in real cigar samples (Cigar No. 39 and Cigar No. 1) as well as flue-cured tobacco varieties, demonstrating its great potential for quality control in the cigar industry, including raw material screening, fermentation monitoring, and product uniformity evaluation.