Analysis of Mycotoxins in Beer Using a Portable Nanostructured

Oct 6, 2016 - A competitive inhibition immunoassay is described for the mycotoxins deoxynivalenol (DON) and ochratoxin A (OTA) in beer using a portabl...
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Analysis of Mycotoxins in Beer Using a Portable Nanostructured Imaging Surface Plasmon Resonance Biosensor Sweccha Joshi, Rumaisha M Annida, Han Zuilhof, Teris A. van Beek, and Michel W.F. Nielen J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.6b04106 • Publication Date (Web): 06 Oct 2016 Downloaded from http://pubs.acs.org on October 6, 2016

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Journal of Agricultural and Food Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

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Journal of Agricultural and Food Chemistry

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Analysis of Mycotoxins in Beer Using a Portable Nanostructured

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Imaging Surface Plasmon Resonance Biosensor Sweccha Joshi, †, ‡ Rumaisha M. Annida, † Han Zuilhof, † Teris A. van Beek, †* Michel W.F. Nielen†,§

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Wageningen, The Netherlands

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TI-COAST, Science Park 904, 1098 XH Amsterdam, The Netherlands

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§

RIKILT Wageningen University & Research, P.O. Box 230, 6700 AE Wageningen, The

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Netherlands

Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE

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*

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[email protected]

Corresponding author (Tel:+31 317 482376; Fax: +31 317 484914; E-mail:

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Journal of Agricultural and Food Chemistry

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ABSTRACT: A competitive inhibition immunoassay is described for the mycotoxins

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deoxynivalenol (DON) and ochratoxin A (OTA) in beer using a portable nanostructured

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imaging surface plasmon resonance (iSPR) biosensor, also referred to as imaging

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nanoplasmonics. The toxins were directly and covalently immobilized on a 3-dimensional

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carboxymethylated dextran (CMD) layer on a nanostructured iSPR chip. The assay is based

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on competition between the immobilized mycotoxins and free mycotoxins in the solution for

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binding to specific antibodies. The chip surface was regenerated after each cycle and the

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combination of CMD and direct immobilization of toxins allowed the chips to be used for

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more than 450 cycles. The limits of detection (LODs) in beer were 17 ng/mL for DON and 7

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ng/mL for OTA (or 0.09 ng/mL after 75 times enrichment). These LODs allowed detection of

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even less than 10% depletion of the tolerable daily intake of DON and OTA by beer.

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Significant cross-reactivity of anti-DON was observed towards DON-3-glucoside and 3-

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acetyl-DON while no cross-reactivity was seen for 15-acetyl-DON. A preliminary in-house

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validation with 20 different batches of beer showed that both toxins can be detected at the

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considered theoretical safe level for beer. The assay can be used for in-field or at-line

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detection of DON in beer and also in barley without pre-concentration, while OTA in beer

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requires an additional enrichment step thus making the latter in its present form less suitable

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for field applications.

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KEYWORDS: Imaging SPR, mycotoxins, beer, nanoplasmonics, deoxynivalenol, ochratoxin

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Journal of Agricultural and Food Chemistry

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INTRODUCTION

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Mycotoxins are the secondary metabolites of fungi commonly found in several foods,

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beverages, and animal feed and are known to be teratogenic, mutagenic, and carcinogenic.1

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They are carried-over from infected barley into malt and ultimately to beer due to their

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thermal stability and relatively good water solubility.2-4 Therefore, careful screening of beer

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ingredients and end products is required for safety of the consumers. The occurrence of

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different mycotoxins in beer has been reported earlier with most studies focusing on

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deoxynivalenol 1 (DON) mainly due to its high incidence.5,6 Another mycotoxin, ochratoxin

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A 5 (OTA), although detected in beer at low concentrations (only