Detection of zearalenone and related metabolites by fluorescence polarization immunoassay

Quantitative determination of zearalenone in wheat by the CSA-NIR technique combined with chemometrics algorithms

In the current study, a colorimetric sensor array combined with near-infrared (NIR) spectroscopy was used to quantitatively analyze zearalenone in wheat. The portable NIR spectrometer was used to scan the porphyrin reaction points of the wheat colorimetric sensor and collect spectral data. Subsequently, based on all the NIR spectral data, the two models and three feature selection algorithms are compared, and the best performance model and the best feature variable input are selected. Concurrently, the Kernel-based Extreme Learning Machine (KELM) model optimized by the two parameter optimization algorithms was compared, and the best parameter optimization algorithm was selected. Among all evaluation models, the KELM model optimized by the Competitive Adaptive Reweighted Sampling algorithm combined with the rime optimization algorithm has the best prediction effect. The predicted RP2 is 0.9900, and the root mean square error of prediction (RMSEP) is 18.4610 μg∙kg-1.

Development of an Immunofluorescence Assay Module for Determination of the Mycotoxin Zearalenone in Water

Project Aquafluosense is designed to develop prototypes for a fluorescence-based instrumentation setup for in situ measurements of several characteristic parameters of water quality. In the scope of the project an enzyme-linked fluorescent immunoassay (ELFIA) method has been developed for the detection of several environmental xenobiotics, including mycotoxin zearalenone (ZON). ZON, produced by several plant pathogenic Fusarium species, has recently been identified as an emerging pollutant in surface water, presenting a hazard to aquatic ecosystems. Due to its physico-chemical properties, detection of ZON at low concentrations in surface water is a challenging task. The 96-well microplate-based fluorescence instrument is capable of detecting ZON in the concentration range of 0.09-400 ng/mL. The sensitivity and accuracy of the analytical method has been demonstrated by a comparative assessment with detection by high-performance liquid chromatography and by total internal reflection ellipsometry. The limit of detection of the method, 0.09 ng/mL, falls in the low range compared to the other reported immunoassays, but the main advantage of this ELFIA method is its efficacy in combined in situ applications for determination of various important water quality parameters detectable by induced fluorimerty-e.g., total organic carbon content, algal density or the level of other organic micropollutants detectable by immunofluorimetry. In addition, the immunofluorescence module can readily be expanded to other target analytes if proper antibodies are available for detection.

Detection Strategies of Zearalenone for Food Safety: A Review

Zearalenone (ZEN) is a toxic compound produced by the metabolism of fungi (genus Fusarium) that threaten the food and agricultural industry belonging to the in foods and feeds. ZEN has toxic effects on human and animal health due to its mutagenicity, teratogenicity, carcinogenicity, nephrotoxicity, immunotoxicity, and genotoxicity. To ensure food safety, rapid, precise, and reliable analytical methods can be developed for the detection of toxins such as ZEN. Different selective molecular diagnostic elements are used in conjunction with different detection strategies to achieve this goal. In this review, the use of electrochemical, colorimetric, fluorometric, refractometric as well as other strategies were discussed for ZEN detection. The success of the sensors in analytical performance depends on the development of receptors with increased affinity to the target. This requirement has been met with different immunoassays, aptamer-assays, and molecular imprinting techniques. The immobilization techniques and analysis strategies developed with the combination of nanomaterials provided high precision, reliability, and convenience in ZEN detection, in which electrochemical strategies perform the best.

Fluorescence Polarization Immunoassay Based on a New Monoclonal Antibody for the Detection of the Zearalenone Class of Mycotoxins in Maize

To develop a sensitive fluorescence polarization immunoassay (FPIA) for screening the zearalenone class of mycotoxins in maize, two new monoclonal antibodies with uniform affinity to the zearalenone class and four fluorescein-labeled tracers were prepared. After careful selection of appropriate tracer-antibody pairs in terms of sensitivity and specificity, a FPIA that could simultaneously detect the zearalenone class with similar sensitivity was developed. Under optimum conditions, the half maximal inhibitory concentrations of the FPIA in buffer were 1.89, 1.97, 2.43, 1.99, 2.27, and 2.44 μg/L for zearalenone, α-zearalenol, β-zearalenol, α-zearalanol, β-zearalanol, and zearalanone, respectively. The limit of detection of FPIA for the zearalenone class was around 12 μg/kg in maize, and the recoveries ranged from 84.6 to 113.8%, with coefficients of variation below 15.3% in spiked samples. Finally, the FPIA was applied for screening naturally contaminated maize samples, and the results indicated a good correlation with that of high-performance liquid chromatography-tandem mass spectrometry.

Advances in Biosensors, Chemosensors and Assays for the Determination of Fusarium Mycotoxins

The contaminations of Fusarium mycotoxins in grains and related products, and the exposure in human body are considerable concerns in food safety and human health worldwide. The common Fusarium mycotoxins include fumonisins, T-2 toxin, deoxynivalenol and zearalenone. For this reason, simple, fast and sensitive analytical techniques are particularly important for the screening and determination of Fusarium mycotoxins. In this review, we outlined the related advances in biosensors, chemosensors and assays based on the classical and novel recognition elements such as antibodies, aptamers and molecularly imprinted polymers. Application to food/feed commodities, limit and time of detection were also discussed.

Using commercial immunoassay kits for mycotoxins: ‘joys and sorrows’?

Rapid test methods are widely used for measuring mycotoxins in a variety of matrices. This review presents an overview of the current commercially available immunoassay rapid test formats. Enzyme linked immune-sorbent assay (ELISA), lateral flow tests, flow through immunoassay, fluorescent polarisation immunoassay, and immunoaffinity columns coupled with fluorometric assay are common formats in the current market. The two existing evaluation programs for commercial testing kits by United State Department of Agricultural Grain Inspection, Packers & Stockyards Administration (USDA-GIPSA) and AOAC Research Institute are introduced. The strengths and weaknesses of these test kits are discussed with regard to the application scope, variance, specificity and cross reactivity, accuracy and precision, and measurement range. Generally speaking, the current commercially available testing kits meet research and industrial needs as ‘fit-for-purpose’. Furthermore, quality assurance concerns and future perspectives are elaborated for broader application of commercial test kits in research, industry and regulatory applications. It is expected that new commercial kits based on advanced technologies such as electrochemical affinity biosensors, molecularly imprinted polymers, surface plasmon resonance, fluorescence resonance energy transfer, aptamer-based biosensors and dynamic light scattering might be available to users in the future. Meanwhile, harmonisation of testing kit evaluation, incorporation of more quality assurance into the testing kit utilisation scheme, and a larger variety of kits available at lower cost will expand the usage of testing kits for food safety testing worldwide.

Cross-reactivity of rapid immunochemical methods for mycotoxins detection towards metabolites and masked mycotoxins: the current state of knowledge

The cross-reactivity of antibodies employed within immunochemistry-based analytical methods may lead to overestimation of the results. Under certain conditions, specifically when controlling mycotoxin maximum limits serious problems can be encountered. Not only the structurally related mycotoxins, such as their masked (conjugated) forms, but also the unidentified matrix components are responsible for concentration overestimation of respective target analytes. The cross-reactivity phenomenon may also pose a risk of miss-interpretation of the proficiency tests results, when the assigned value becomes influenced by over-estimated results reported by users of immunochemical tests. In this paper, the current state of the knowledge on trueness problems associated with the rapid screening immunochemical methods have been reviewed. Special attention is focused on discussion of cross-reactivity in the ELISA tests, because this rapid test dominates the routine screening practice. However, the cross-reactions reported in lateral flow test strips, fluorescence polarisation immunoassay, or immunosensors have also been addressed.

Fluorescence polarisation immunoassays for rapid, accurate and sensitive determination of mycotoxins

Fluorescence polarisation immunoassay (FPIA) is a type of homogeneous assay. For low molecular weight antigens, such as mycotoxins, it is based on the competition between an unlabeled antigen and its fluorescent-labelled derivative (tracer) for an antigen-specific antibody. The antigen content is determined by measuring the reduction of fluorescence polarisation signal, which in turn is determined by the reduction of tracer molecules able to bind antibody in solution. To develop a competitive FPIA for mycotoxin measurement the tracer has to be synthesised and its binding response with a specific antibody should be tested. Selectivity and sensitivity of the FPIA methods are strictly related to the antibody/tracer combination used. Several FPIA methods for the detection of the major mycotoxins, including aflatoxins, fumonisins, ochratoxin A, deoxynivalenol, T-2 and HT-2 toxins and zearalenone in food and beverages have been developed in the last decade. Basic principles, key elements, advantages and limitations of these methods are reviewed. These FPIA methods are simple, readily automated, rapid, and suitable for high-throughput screening, as well as for the reliable quantitative determination of mycotoxins in foods and commodities.

Implications of fungal infections and mycotoxins in camel diseases in Saudi Arabia

Natural feed ingredients (corn, barley and wheat bran) and compound feed (manufactured pellet) are two types of fodder used for animal feeding, especially camel in Saudi Arabia. Twenty samples of each type of fodder were collected from seven different regions and screened for the presence of fungi, aflatoxins, ochratoxin and zearalenone. Fungal isolation of natural feed ingredients yielded 10 genera and 38 species of different fungi. Compound fodder samples were contaminated with 16 genera and 32 species of fungi. Total counts of Aspergillus, Penicillium and Fusarium in the animal feed samples were ranged from 54 to 223 × 10(3), 31.9 to 60 × 10(3) and 18 to 29 × 10(3) CFU/g, respectively. These isolates when tested for aflatoxin, ochratoxin and zearalenone producing ability, revealed this property in only four isolate, identified as Aspergillus flavus, A. parasiticus, A. ochraceus and Fusarium graminaerum. The percentage of toxigenic fungi was ranged from 5.5% to 30% for natural feed ingredients and from 4.5% to 20% for compound feed. The incidence of aflatoxins (AFT) in samples of natural feed ingredients was found to be ranged from 1 to 24.8 ppb, ochratoxin A (OTA) ranged from 1 to 44 ppb and zearalenone (ZON) ranged from 1 to 23 ppb. Contamination of compound feed with aflatoxin and ochratoxin A was ranged from 1 to 6.4 ppb and 1 to 4.7 ppb, respectively. All samples collected were found contaminated with fungi or their toxins and natural feed samples were more contaminated compared to compound feed samples. The concentrations detected were in the allowed limit (<20 ppb) except four samples of natural feed ingredients which were above the allowed limit of the tested mycotoxins. In conclusion, feed samples were contaminated with fungi and some toxigenic isolates which were responsible about mycotoxin production. Some samples had exceeded amount of AFT, OTA and ZON and may be contaminated with other mycotoxins which mean implication of fungi in camel health problems and death in Saudi Arabia.

A rapid fluorescence polarization immunoassay for the determination of T-2 and HT-2 toxins in wheat

A rapid fluorescence polarization (FP) immunoassay has been developed for the simultaneous determination of T-2 and HT-2 toxins in naturally contaminated wheat samples. Syntheses of four fluorescein-labelled T-2 or HT-2 toxin tracers were carried out and their binding response with seven monoclonal antibodies was evaluated. The most sensitive antibody-tracer combination was obtained by using an HT-2-specific antibody and a fluorescein-HT-2 tracer. The developed competitive FP immunoassay in solution showed high cross-reactivity for T-2 toxin (CR% = 100%) while a very low CR% for neosolaniol (0.12%) and no cross-reactivity with other mycotoxins frequently occurring in wheat. A rapid extraction procedure using 90% methanol was applied to wheat samples prior to FP immunoassay. The average recovery from spiked wheat samples (50 to 200 μg kg(-1)) was 96% with relative standard deviation generally lower than 8%. A limit of detection of 8 μg kg(-1) for the combined toxins was determined. Comparative analyses of 45 naturally contaminated and spiked wheat samples by both the FP immunoassay and high-performance liquid chromatography/immunoaffinity clean-up showed a good correlation (r = 0.964). These results, combined with the rapidity (10 min) and simplicity of the assay, show that this method is suitable for high throughput screening as well as for quantitative determination of T-2 and HT-2 toxins in wheat.

Fluorescence polarization immunoassay of mycotoxins: a review

Immunoassays are routinely used in the screening of commodities and foods for fungal toxins (mycotoxins). Demands to increase speed and lower costs have lead to continued improvements in such assays. Because many reported mycotoxins are low molecular weight (below 1 kDa), immunoassays for their detection have generally been constructed in competitive heterogeneous formats. An exception is fluorescence polarization immunoassay (FPIA), a homogeneous format that does not require the separation of bound and free labels (tracer). The potential for rapid, solution phase, immunoassays has been realized in the development of FPIA for many of the major groups of mycotoxins, including aflatoxins, fumonisins, group B trichothecenes (primarily deoxynivalenol), ochratoxin A, and zearalenone. This review describes the basic principles of FPIA and summarizes recent research in this area with regard to mycotoxins.

Development and validation of a gold nanoparticle immunochromatographic assay (ICG) for the detection of zearalenone

A monoclonal antibody (mAb)-based gold nanoparticle immunochromatographic assay (ICG) for zearalenone detection was developed, optimized, and validated. The detection limits of ICG optimized with appropriate amounts of zearalenone-bovine serum albumin and gold nanoparticle-mAb to zearalenone were 2.5 ng/mL and 30 μg/kg for the standard solution and spike sample, respectively, and a weak cross-reaction for α-zearalenol and β-zearalenol was observed. The assay required only 15 min to obtain results and one step to perform the assay. In validation, the results obtained from spiked corn (10, 20, 30, 50, and 100 μg/kg) and naturally contaminated corn samples by the ICG were in good agreement with those obtained by direct competitive enzyme-linked immunosorbent assay (DC-ELISA) and high-performance liquid chromatography (HPLC). Therefore, the results obtained in this study could be used as basic research for the development of zearalenone-ICG, and the ICG developed could be a useful on-site screening tool for the rapid detection of zearalenone in corn without special instrumentation.

Mycotoxin detection plays "cops and robbers": cyclodextrin chemosensors as specialized police?

As in a cops and robbers play we discover new mycotoxins and metabolites everyday and we are forced to develop new molecules quickly as chemo- or biosensors or to modify existing molecules able to recognize these new hazardous compounds. This will result in an enormous cost saving to agro-food industry through the prevention and reduction of product recalls and reduced treatment costs. Here we present a brief review of the rapid methods used to detect mycotoxins, considering usefulness and limits. Then we propose a new fast, efficient and cheap methodology, based on a combination of computer chemistry aided design and fluorescence, that can help to drive synthesis in a more efficient way.

Fluorescence polarization immunoassays and related methods for simple, high-throughput screening of small molecules

Fluorescence polarization immunoassay (FPIA) is a homogeneous (without separation) competitive immunoassay method based on the increase in fluorescence polarization (FP) of fluorescent-labeled small antigens when bound by specific antibody. The minimum detectable quantity of FPIAs with fluorescein label (about 0.1 ng analyte) is comparable with chromatography and ELISA methods, although this may be limited by sample matrix interference. Because of its simplicity and speed, FPIA is readily automated and therefore suitable for high-throughput screening (HTS) in a variety of application areas. Systems that involve binding of ligands to receptor proteins are also susceptible to analysis by analogous FP methods employing fluorescent-labeled ligand and HTS applications have been developed, notably for use in candidate drug screening.

Immunochemical methods for rapid mycotoxin detection: Evolution from single to multiple analyte screening: A review

This review focuses on recent developments in immunochemical methods for detection of mycotoxins, with a particular emphasis on simultaneous multiple analyte determination. This includes high-throughput instrumental analysis for the laboratory environment (microtitre plate enzyme-linked immunoabsorbant assay (ELISA), different kinds of immunosensors, fluorescence polarization immunoassay, and capillary electrophoretic immunoassay), as well as rapid visual tests for on-site testing (lateral-flow, dipstick, flow-through and column tests). For each type of immunoassay, perspectives for multiple analyte application are discussed and examples cited.

Capillary electrophoresis of the mycotoxin zearalenone using cyclodextrin-enhanced fluorescence

Certain of the cyclodextrins are capable of significantly enhancing the native fluorescence of the estrogenic mycotoxin zearalenone (ZEN). Twenty-two cyclodextrins (CDs) were screened for their ability to enhance the fluorescence of ZEN in a capillary electrophoresis-laser induced fluorescence (CE-LIF) format. Of the CDs that were examined heptakis (2,6-di-O-methyl)-beta-CD gave the greatest enhancement. The heptakis (2,6-di-O-methyl)-beta-CD was applied to the development of a CE-LIF method for detection of ZEN in maize. The resulting method was capable of detecting ZEN with a limit of quantitation of 5 ng/g maize. Recoveries of ZEN from maize spiked over the range from 5 ng/g to 500 ng/g averaged 103.1+/-8.5% (n=20). The CE-LIF method will be useful for future studies of ZEN in maize.

Optimization of a fluorescence polarization immunoassay for rapid quantification of deoxynivalenol in durum wheat-based products

A fluorescence polarization immunoassay previously described for deoxynivalenol (DON) screening in wheat was optimized for the rapid quantification of DON in durum wheat kernels, semolina, and pasta. A background signal was observed in both spiked and naturally contaminated samples, strictly depending on the testing matrix. After subtracting the background DON level for durum wheat (0.27 microg of DON per g), semolina (0.08 microg of DON per g), and pasta (0.04 microg of DON per g), an accurate quantification of DON was possible at levels greater than 0.10 microg/g for all matrices. Average recoveries from spiked samples (0.25 to 1.75 microg/g) were 98, 102, and 101% for wheat, semolina, and pasta, respectively. Comparative analyses of 35 naturally contaminated durum wheat samples, 22 semolina samples, and 26 pasta samples performed by both the fluorescence polarization method and high-pressure liquid chromatography/immunoaffinity cleanup showed a good correlation (r > 0.995). The fluorescence polarization method showed better accuracy and precision with respect to the high-pressure liquid chromatography method and is suitable for the rapid and quantitative determination of DON in durum wheat-based products at levels foreseen by existing or coming international regulations.

A review of rapid methods for the analysis of mycotoxins

An overview is presented of the analysis of mycotoxins by rapid methods such as: enzyme linked immunosorbent assay (ELISA); flow through membrane based immunoassay; immunochromatographic assay; fluorometric assay with immunoaffinity clean-up column or with a solid phase extraction clean-up column; and fluorescence polarization method. These methods are currently commercially available and are reliable, rapid methods. This review focuses on the basic principle of each rapid method as well as advantages and limitations of each method. Additionally, we address other emerging technologies of potential application in the analysis of mycotoxins.