Competitive upconversion-linked immunoassay using peptide mimetics for the detection of the mycotoxin zearalenone

Publication year: 2020
Authors: Riikka Peltomaa a,b,1, Zdeněk Farka a,c, Matthias J. Mickert a,2, Julian C. Brandmeier a, Matěj Pastucha c, Antonín Hlaváček d, Mónica Martínez-Orts e, Ángeles Canales e, Petr Skládal c, Elena Benito-Peña b, María C. Moreno-Bondi b, Hans H. Gorris a
Affiliations:

a - Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, Universitätsstraße 31, 93040, Regensburg, Germany
b - Department of Analytical Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, Plaza de las Ciencias, Ciudad Universitaria, 28040, Madrid, Spain
c - Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
d - Institute of Analytical Chemistry of the Czech Academy of Sciences, Veveří 97, 602 00, Brno, Czech Republic
e - Department of Organic Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, Plaza de las Ciencias, Ciudad Universitaria, 28040, Madrid, Spain

Published in: Biosensors and Bioelectronics, Vol. 170, p. 112683
doi: 10.1016/j.bios.2020.112683

Due to increasing food safety standards, the analysis of mycotoxins has become essential in the food industry. In this work, we have developed a competitive upconversion-linked immunosorbent assay (ULISA) for the analysis of zearalenone (ZEA), one of the most frequently encountered mycotoxins in food worldwide. Instead of a toxin-conjugate conventionally used in competitive immunoassays, we designed a ZEA mimicking peptide extended by a biotin-linker and confirmed its excellent suitability to mimic ZEA by nuclear magnetic resonance (NMR) and surface plasmon resonance (SPR) analysis. Upconversion nanoparticles (UCNP, type NaYF4:Yb,Tm) served as background-free optical label for the detection of the peptide mimetic in the competitive ULISA. Streptavidin-conjugated UCNPs were prepared by click reaction using an alkyne-PEG-neridronate linker. The UCNP conjugate clearly outperformed conventional labels such as enzymes or fluorescent dyes. With a limit of detection of 20 pg mL−1 (63 pM), the competitive ULISA is well applicable to the detection of ZEA at the levels set by the European legislation. Moreover, the ULISA is specific for ZEA and its metabolites (α- and β-zearalenol) without significant cross-reactivity with other related mycotoxins. We detected ZEA in spiked and naturally contaminated maize samples using liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) as a reference method to demonstrate food analysis in real samples.


MP-SPR keywords: food safety, immunosensing, peptide mimetic, upconversion nanoparticle, zearalenone