Peltomaa, Riikka JohannaAmaro Torres, FranciscoCarrasco, SergioOrellana Moraleda, GuillermoBenito Peña, María ElenaMoreno Bondi, María Cruz2024-01-162024-01-162018Riikka Peltomaa, Francisco Amaro-Torres, Sergio Carrasco, Guillermo Orellana, Elena Benito-Peña, and María C. Moreno-Bondi ACS Nano 2018 12 (11), 11333-11342 DOI: 10.1021/acsnano.8b060941936-085110.1021/acsnano.8b06094https://hdl.handle.net/20.500.14352/93316Homogeneous immunoassays represent an attractive alternative to traditional heterogeneous assays due to their simplicity, sensitivity, and speed. On the basis of a previously identified epitope-mimicking peptide, or mimotope, we developed a homogeneous fluorescence quenching immunoassay based on gold nanoparticles (AuNPs) and a recombinant epitope-mimicking fusion protein for the detection of mycotoxin fumonisin B1 (FB1). The fumonisin mimotope was cloned as a fusion protein with a yellow fluorescent protein that could be used directly as the tracer for FB1 detection without the need of labeling or a secondary antibody. Furthermore, owing to the fluorescence quenching ability of AuNPs, a homogeneous immunoassay could be performed in a single step without washing steps to separate the unbound tracer. The homogeneous quenching assay showed negligible matrix effects in 5% wheat extract and high sensitivity for FB1 detection, with a dynamic range from 7.3 to 22.6 ng/mL, a detection limit of 1.1 ng/mL, and IC50 value of 12.9 ng/mL, which was significantly lower than the IC50 value of the previously reported assay using the synthetic counterpart of the same mimotope in a microarray format. The homogeneous assay was demonstrated to be specific for fumonisins B1 and B2, as no significant cross-reactivity with other mycotoxins was observed, and acceptable recoveries (86% for FB1 2000 μg/kg and 103% for FB1 4000 μg/kg), with relative standard deviation less than 6.5%, were reported from spiked wheat samples, proving that the method could provide a valuable tool for simple analysis of mycotoxin-contaminated food samples.engAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/journal article1936-086Xhttps://doi.org/10.1021/acsnano.8b06094open access543Fluorescent proteinMimotopeGold nanoparticleQuenchingHomogeneous immunoassayMycotoxinQuímica analítica (Química)23 Química33 Ciencias Tecnológicas24 Ciencias de la Vida32 Ciencias Médicas