Zearalenone sensing with molecularly imprinted polymers and tailored fluorescent probes

A molecularly imprinted polymer (MIP)-based optode has been developed for zearalenone (ZON) mycotoxin analysis. The automated flow-through assay is based on the displacement of tailor-made highly fluorescent tracers by the analyte from a MIP prepared by UV irradiation of a mixture of cyclododecyl 2,4-dihydroxybenzoate (template, ZON mimic), 1-allyl piperazine (functional monomer), trimethylolpropane trimethacrylate (crosslinker) and 2,2′-azobisisobutyronitrile in acetonitrile (porogen). Three fluorescent analogues of ZON, namely 2,4-dihydroxybenzoic acid 2-[methyl(7-nitro-benzo[1,2,5]oxadiazol-4-yl)amino]ethyl ester (NBDRA), 2,4-dihydroxy-N-pyren-1-ylmethylbenzamide (PMRA) and of 2,4-dihydroxybenzoic acid 2-[(pyrene-l-carbonyl)amino] ethyl ester (PARA), have been molecularly engineered for the assay development. The pyrene-containing tracers also inform on the characteristics of the microenvironment of the MIP binding sites. PARA has been finally selected to optimize the ZON displacement fluorosensor, that shows a limit of detection of 2.5 × 10−5 M in acetonitrile. A positive cross-reactivity has been found for β-zearalenol, but not for resorcinol, resorcylic acid, 17β-estradiol, estrone or bisphenol-A.