Bis(imidazole)-Anthracene Functionalized Fluorescent Molecularly Imprinted Polymer for Specific and Rapid Detection of Capsaicin in Edible Oils

Capsaicin is an ideal marker for identifying gutter oil due to its lipophilic nature and chemical stability. The development of sensitive, rapid, and low-cost detection methods for capsaicin is urgently needed to ensure food authenticity. Here, a fluorescent functional monomer of 1,8-bis( N -vinylimidazol- N ′-methyl)anthracene bromide was employed to synthesize fluorescent molecularly imprinted polymers (MIPs) for capsaicin using two different cross-linkers: hydrophilic N,N ′-methylenebis(acrylamide) (MBAA) and hydrophobic ethylene glycol dimethacrylate (EGDMA). The MBAA-cross-linked and EGDMA-cross-linked MIPs exhibited imprinting factors of 2.1 and 3.5, and cross-reactivity factors of 1.3–2.0 and 2.6–10.0, respectively, suggesting their good specificity to capsaicin. Both MIPs displayed a rapid detection time of 10 min. The fluorescent MIP-based detection systems achieved low detection limits of 0.027–0.039 μM and recovery rates of 80–105% in spiked edible oil samples. These features of such fluorescent MIPs demonstrate their promising future for the rapid detection of capsaicin in real edible oil samples to ensure food authenticity.