Automated regenerable microarray-based immunoassay for rapid parallel quantification of mycotoxins in cereals

A multiplex microarray lateral flow immunoassay device for simultaneous determination of five mycotoxins in rice

Co-occurrence of multiple mycotoxins is a growing global food safety concern due to their harmful effects on humans and animals. This study developed an eco-friendly sample preparation method and an innovative multiplex microarray-based lateral flow immunoassay, using a novel portable reader for on-site simultaneous determination of five regulated mycotoxins-aflatoxin B1, T-2 toxin, zearalenone, deoxynivalenol, and fumonisin B1 in rice. The eco-friendly and ultrafast extraction procedure utilizes a bio-based solvent. Principally, the microarray signals generated through a novel luminescent organic dye were captured to quantify mycotoxin levels in samples using a portable reader installed with a user-friendly interface. The assay demonstrates accurate detection and quantification of these mycotoxins, with recoveries ranging from 77% to 127%. Detection limits ranged from 0.56 to 1.89 μg/kg, which were well below their regulatory limits, with a relative standard deviation below 25%. This analytical system provides an on-site method for detecting multiple mycotoxins in rice.

Recent Advances in Mycotoxin Determination in Fish Feed Ingredients

Low-cost plant-based sources used in aquaculture diets are prone to the occurrence of animal feed contaminants, which may in certain conditions affect the quality and safety of aquafeeds. Mycotoxins, a toxic group of small organic molecules produced by fungi, comprise a frequently occurring plant-based feed contaminant in aquafeeds. Mycotoxin contamination can potentially cause significant mortality, reduced productivity, and higher disease susceptibility; thus, its timely detection is crucial to the aquaculture industry. The present review summarizes the methodological advances, developed mainly during the past decade, related to mycotoxin detection in aquafeed ingredients, namely analytical, chromatographic, and immunological methodologies, as well as the use of biosensors and spectroscopic methods which are becoming more prevalent. Rapid and accurate mycotoxin detection is and will continue to be crucial to the food industry, animal production, and the environment, resulting in further improvements and developments in mycotoxin detection techniques.

A Novel Fluorescent Aptasensor Based on Real-Time Fluorescence and Strand Displacement Amplification for the Detection of Ochratoxin A

It is urgently necessary to develop convenient, reliable, ultrasensitive and specific methods of ochratoxin A determination in food safety owing to its high toxicity. In the present study, an ultrasensitive and labeled-free fluorescent aptamer sensor combining real-time fluorescence with strand displacement amplification (SDA) was fabricated for the determination of OTA. In the presence of OTA, the OTA–aptamer combines with OTA, thus opening hairpins. Then, SDA primers specifically bind to the hairpin stem, which is used for subsequent amplification as a template. SDA amplification is initiated under the action of Bst DNA polymerase and nicking endonuclease. The amplified products (ssDNA) are dyed with SYBR Green II and detected with real-time fluorescence. The method has good linearity in the range of 0.01–50 ng mL⁻¹, with the lowest limit of detection of 0.01 ng mL⁻¹. Additionally, the fluorescent aptamer sensor shows outstanding specificity and reproducibility. Furthermore, the sensor shows excellent analytical performance in the artificial labeled detection of wheat and oat samples, with a recovery rate of 96.1~100%. The results suggest that the developed sensor has a promising potential application for the ultrasensitive detection of contaminants in food.

Recent Progress in Rapid Determination of Mycotoxins Based on Emerging Biorecognition Molecules: A Review

Mycotoxins are secondary metabolites produced by fungal species, which pose significant risk to humans and livestock. The mycotoxins which are produced from Aspergillus, Penicillium, and Fusarium are considered most important and therefore regulated in food- and feedstuffs. Analyses are predominantly performed by official laboratory methods in centralized labs by expert technicians. There is an urgent demand for new low-cost, easy-to-use, and portable analytical devices for rapid on-site determination. Most significant advances were realized in the field bioanalytical techniques based on molecular recognition. This review aims to discuss recent progress in the generation of native biomolecules and new bioinspired materials towards mycotoxins for the development of reliable bioreceptor-based analytical methods. After brief presentation of basic knowledge regarding characteristics of most important mycotoxins, the generation, benefits, and limitations of present and emerging biorecognition molecules, such as polyclonal (pAb), monoclonal (mAb), recombinant antibodies (rAb), aptamers, short peptides, and molecularly imprinted polymers (MIPs), are discussed. Hereinafter, the use of binders in different areas of application, including sample preparation, microplate- and tube-based assays, lateral flow devices, and biosensors, is highlighted. Special focus, on a global scale, is placed on commercial availability of single receptor molecules, test-kits, and biosensor platforms using multiplexed bead-based suspension assays and planar biochip arrays. Future outlook is given with special emphasis on new challenges, such as increasing use of rAb based on synthetic and naïve antibody libraries to renounce animal immunization, multiple-analyte test-kits and high-throughput multiplexing, and determination of masked mycotoxins, including stereoisomeric degradation products.

An Aptamer-Array-Based Sample-to-Answer Biosensor for Ochratoxin A Detection via Fluorescence Resonance Energy Transfer

Food toxins are a hidden threat that can cause cancer and tremendously impact human health. Therefore, the detection of food toxins in a timely manner with high sensitivity is of paramount importance for public health and food safety. However, the current detection methods are relatively time-consuming and not practical for field tests. In the present work, we developed a novel aptamer-chip-based sample-to-answer biosensor (ACSB) for ochratoxin A (OTA) detection via fluorescence resonance energy transfer (FRET). In this system, a cyanine 3 (Cy3)-labeled OTA-specific biotinylated aptamer was immobilized on an epoxy-coated chip via streptavidin-biotin binding. A complementary DNA strand to OTA aptamer at the 3′-end was labeled with a black hole quencher 2 (BHQ2) to quench Cy3 fluorescence when in proximity. In the presence of OTA, the Cy3-labeled OTA aptamer bound specifically to OTA and led to the physical separation of Cy3 and BHQ2, which resulted in an increase of fluorescence signal. The limit of detection (LOD) of this ACSB for OTA was 0.005 ng/mL with a linearity range of 0.01–10 ng/mL. The cross-reactivity of ACSB against other mycotoxins, ochratoxin B (OTB), aflatoxin B1 (AFB1), zearalenone (ZEA), or deoxynilvalenol (DON), was less than 0.01%. In addition, this system could accurately detect OTA in rice samples spiked with OTA, and the mean recovery rate of the spiked-in OTA reached 91%, with a coefficient of variation (CV) of 8.57–9.89%. Collectively, the ACSB may represent a rapid, accurate, and easy-to-use platform for OTA detection with high sensitivity and specificity.

Magnetic beads-assisted fluorescence aptasensing approach based on dual DNA tweezers for detection of ochratoxin A and fumonisin B1 in wine and corn

A magnetic beads (MBs)-assisted fluorescence aptasensing approach based on dual DNA tweezers and magnetic separation was established for the detection of ochratoxin A (OTA) and fumonisin B₁ (FB₁). A dual DNA tweezers structure with four ends linked with fluorophores (FAM, ROX) and quenchers (BHQ₁, BHQ₂) was designed, and produced the high initial fluorescence signals because of the long spatial distance between FAM and BHQ₁, ROX, and BHQ₂. Bio-aptamer/anti-aptamer of OTA and bio-aptamer/anti-aptamer of FB₁ were respectively annealed to form dsDNA, and immobilized to MBs coated with streptavidin (SA). With the existence of OTA and FB₁, OTA and FB₁ preferentially bound with their respective bio-aptamers, which made anti-aptamers dissociate from dsDNA coupled on MBs. After magnetic separation, the dissociated anti-aptamers reacted with dual DNA tweezers, respectively, which made DNA tweezers close and the fluorescence was quenched. The linear ranges of approach for OTA and FB₁ detection were 0.05-20 ng/mL and 0.1-40 ng/mL, respectively. The limit of detection for OTA and FB₁ was 0.029 ng/mL and 0.061 ng/mL. The prepared MBs-assisted fluorescence aptasensing approach was applied to detect OTA and FB₁ in spiked red wine and corn samples, which showed good recoveries between 92 and 106%.

Trichothecenes in Food and Feed, Relevance to Human and Animal Health and Methods of Detection: A Systematic Review

Trichothecene mycotoxins are sesquiterpenoid compounds primarily produced by fungi in taxonomical genera such as Fusarium, Myrothecium, Stachybotrys, Trichothecium, and others, under specific climatic conditions on a worldwide basis. Fusarium mold is a major plant pathogen and produces a number of trichothecene mycotoxins including deoxynivalenol (or vomitoxin), nivalenol, diacetoxyscirpenol, and T-2 toxin, HT-2 toxin. Monogastrics are sensitive to vomitoxin, while poultry and ruminants appear to be less sensitive to some trichothecenes through microbial metabolism of trichothecenes in the gastrointestinal tract. Trichothecene mycotoxins occur worldwide however both total concentrations and the particular mix of toxins present vary with environmental conditions. Proper agricultural practices such as avoiding late harvests, removing overwintered stubble from fields, and avoiding a corn/wheat rotation that favors Fusarium growth in residue can reduce trichothecene contamination of grains. Due to the vague nature of toxic effects attributed to low concentrations of trichothecenes, a solid link between low level exposure and a specific trichothecene is difficult to establish. Multiple factors, such as nutrition, management, and environmental conditions impact animal health and need to be evaluated with the knowledge of the mycotoxin and concentrations known to cause adverse health effects. Future research evaluating the impact of low-level exposure on livestock may clarify the potential impact on immunity. Trichothecenes are rapidly excreted from animals, and residues in edible tissues, milk, or eggs are likely negligible. In chronic exposures to trichothecenes, once the contaminated feed is removed and exposure stopped, animals generally have an excellent prognosis for recovery. This review shows the occurrence of trichothecenes in food and feed in 2011-2020 and their toxic effects and provides a summary of the discussions on the potential public health concerns specifically related to trichothecenes residues in foods associated with the exposure of farm animals to mycotoxin-contaminated feeds and impact to human health. Moreover, the article discusses the methods of their detection.

Simultaneous electrochemical determination of ochratoxin A and fumonisin B1 with an aptasensor based on the use of a Y-shaped DNA structure on gold nanorods

A complementary DNA (cDNA) was designed to simultaneously hybridize with the ochratoxin A (OTA) aptamer and the fumonisin B1 (FB1) aptamer to form a unique Y-shaped DNA structure and to achieve simultaneous detection. Gold nanorods (AuNRs) were used to immobilize thionine (Th), thiolated ferrocene (Fc), thiolated OTA aptamer (Apt1), and thiolated FB1 aptamer (Apt2), to form an amplified signal element and a recognition element. The Apt1-AuNRs-Th complex and the Apt2-AuNRs-Fc complex hybridize with cDNA to form a unique Y-DNA structure on a gold electrode. This produces two initial electrochemical signals [with 177 μΑ cm^-2 near -0.2 V, and 3121 μΑ cm^-2 near +0.46 V (vs. Ag/AgCl)] by differential pulse voltammetry. Upon addition of 0.1 ng mL^-1 OTA and 0.1 ng mL^-1 FB1, the aptamers bind the two toxins. This results in the release of Apt1-AuNRs-Th and Apt2-AuNRs-Fc, so the peak currents densities decrease to 115 μΑ cm^-2 and 209 μΑ cm^-2. The assay allows simultaneous determination of OTA and FB1 in the 1.0 pg·mL^-1 to 100 ng·mL^-1 concentration ranges, with LODs of 0.47 and 0.26 pg·mL^-1. The assay is reproducible, stable and specific. It was applied to the determination of OTA and FB1 in spiked beer, with recoveries between 89.0% and 102.0%. Graphical abstractSchematic representation of OTA and FB₁ detection based on Apt₂-AuNRs-Fc/Apt₁-AuNRs-Th/cDNA/AuE. (AuNRs: Gold nanorods; Th: thionine; Fc: ferrocene; SH: thiol; BSA: Bovine serum albumin; cDNA: Complementary DNA; Apt₁: Aptamer1; Apt₂: Aptamer2; OTA: Ochratoxin A; FB₁: Fumonisin B₁).

A competitive aptamer chemiluminescence assay for ochratoxin A using a single silica photonic crystal microsphere

We designed a competitive aptamer chemiluminescence assay for ochratoxin A (OTA) on the surface of a single silica photonic crystal microsphere (SPCM) in cereal samples. The structural color of SPCMs is used to recognize and trace the microspheres during process of detection. Anti-aptamer was immobilized on the surface of SPCM. OTA and anti-aptamer competed to bind to aptamer when OTA and its aptamer (labeled by biotin at 5'end) were added in the system. The chemiluminescence signal was developed by the horseradish peroxidase (HRP), luminol and H₂O₂. The molecules on the single SPCM can produce enough chemiluminescence signal intensity for quantitative detection for OTA. The linear detection range for OTA was from 1 pg/mL to 1 ng/mL and recovery rates were 89%-95%, 81%-92% and 94%-105% in rice, wheat and corn, respectively. The results showed that the developed method for OTA using a single SPCM has a great application potential in cereal samples.

TiO2 Nanolayer-Enhanced Fluorescence for Simultaneous Multiplex Mycotoxin Detection by Aptamer Microarrays on a Porous Silicon Surface

A new aptamer microarray method on the TiO₂-porous silicon (PSi) surface was developed to simultaneously screen multiplex mycotoxins. The TiO₂ nanolayer on the surface of PSi can enhance the fluorescence intensity 14 times than that of the thermally oxidized PSi. The aptamer fluorescence signal recovery principle was performed on the TiO₂-PSi surface by hybridization duplex strand DNA from the mycotoxin aptamer and antiaptamer, respectively, labeled with fluorescence dye and quencher. The aptamer microarray can simultaneously screen for multiplex mycotoxins with a dynamic linear detection range of 0.1-10 ng/mL for ochratoxin A (OTA), 0.01-10 ng/mL for aflatoxins B₁ (AFB₁), and 0.001-10 ng/mL for fumonisin B₁ (FB₁) and limits of detection of 15.4, 1.48, and 0.21 pg/mL for OTA, AFB₁, and FB₁, respectively. The newly developed method shows good specificity and recovery rates. This method can provide a simple, sensitive, and cost-efficient platform for simultaneous screening of multiplex mycotoxins and can be easily expanded to the other aptamer-based protocol.

Microarray-Based Immunoassay for Parallel Quantification of Multiple Mycotoxins in Oat

Because multianalyte methods are highly desirable in order to keep analysis time and costs low, the biosensor development increasingly focuses on parallel analysis of several mycotoxins. Here, we describe an indirect competitive immunoassay on regenerable, reusable glass microchips for the parallel determination of aflatoxins, ochratoxin A, deoxynivalenol, and fumonisin B1 in oat extracts, using a fully automated flow-through device with chemiluminescence readout.

Immune-affinity monolithic array with chemiluminescent detection for mycotoxins in barley

BACKGROUND

Mycotoxins are produced by fungi as secondary metabolites. They often multi-contaminate food and feed commodities posing a health risk to humans and animals. Fast and easy multiplex screening could be thought as a useful tool for detection of multi-contaminated food and feed commodities.

RESULTS

A highly sensitive immune-affinity monolithic arrays for detecting the mycotoxins zearalenone, deoxynivalenol, T-2 toxin, HT-2 toxin, aflatoxins, ochratoxin A, and fumonisin B₁ were fabricated using UV induced co-polymerisation. The mycotoxin antibodies firstly reacted with functional monomer to form antibody/functional monomer bio-conjugates. Subsequently, the antibody/functional monomer bio-conjugates co-polymerised with cross-linker to form mycotoxins immune-affinity arrays. With optimal fabrication conditions, all mycotoxin immune-affinity monolithic arrays exhibited a linear response spanning three orders of magnitude. And the immune-affinity monolithic array has a low detection limit and has a good uniformity (intra-assay CV, and inter-assay CV both <8%).

CONCLUSION

The fabricated mycotoxin immune-affinity monolithic arrays were proved as a sensitive, stable and economical tool in real food samples detection. Moreover, the mycotoxin immune-affinity monolithic arrays would be able to minimise manipulation steps: add samples and enzyme labelled mycotoxins, and detect CL signals. © 2016 Society of Chemical Industry.

Low-cost humic acid-bonded silica as an effective solid-phase extraction sorbent for convenient determination of aflatoxins in edible oils

Aflatoxins (AFs) are highly toxic, mutagenic, carcinogenic, and teratogenic secondary metabolites produced by the toxigenic fungi Aspergillus flavus and Aspergillus parasiticus. AFs tend to contaminate a wide range of foods which is a serious and recurring food safety problem worldwide. Currently, immunoaffinity chromatography (IAC) has become the most conventional sample clean-up method for determining AFs in foodstuffs. However, IAC method is limited in the large-scale food analysis because it requires the use of expensive disposable cartridges and the IA procedure is time-consuming. Herein, to achieve the cost-effective determination of AFs in edible oils, we developed a promising solid-phase extraction (SPE) method based on commercially available humic acid-bonded silica (HAS) sorbent, followed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) analysis. In HAS-SPE, AFs can be captured by the HAS sorbent with both hydrophobic and hydrophilic interactions, whereas the oil matrix was captured only with the hydrophobic interactions. The oil matrix can be sufficiently washed off with isopropanol, while the AFs were still retained on the SPE packing, thus achieving selective extraction of AFs and clean-up of oil matrices. Under the optimal conditions of HAS-SPE, satisfactory recoveries ranging from 82% to 106% for four AFs (B₁, B₂, G₁, and G₂) were achieved in various oil matrices, containing blended oil, tea oil, rapeseed oil, peanut oil, sunflower seed oil, corn oil, blended olive oil, rice oil, soybean oil, and sesame oil. Only minor matrix effects ranging from 99% to 105% for four AFs were observed. Moreover, the LODs of AFs between 0.012 and 0.035 μg/kg completely meet the regulatory levels fixed by the EU, China or other countries. The methodology was further validated for assaying the naturally contaminated peanut oils, and consistent results between the HAS-SPE and the referenced IAC were obtained. In addition, HAS-SPE can directly treat diluted oil sample without liquid-liquid extraction and is automatable, thus making it simple and convenient for the large-scale determination of AFs in edible oils. Using this method, we successfully detected four AFs in the naturally contaminated peanut oils, which is, to the best of our knowledge, the first report about the determination of AFs in edible oils using HA-based SPE.

Validation Procedure for Multiplex Antibiotic Immunoassays Using Flow-Based Chemiluminescence Microarrays

Small molecules like antibiotics or other pharmaceuticals can be detected and quantified, among others, with indirect competitive immunoassays. With regard to multiplex quantification, these tests can be performed as chemiluminescence microarray immunoassays, in which, in principle, the analyte in the sample and the same substance immobilized on the chip surface compete for a limited number of specific antibody binding sites. The amount of the specific primary antibody that has been bound to the surface is visualized by means of a chemiluminescence reaction.Validated quantitative confirmatory methods for the detection of contaminants, for example drug residues, in food samples usually comprise chromatographic analysis and spectrometric detection, e.g., HPLC-MS, GC-MS, or GC with electron capture detection. Here, we describe a validation procedure (according to the Commission Decision of the European Communities 2002/657/EC) for multiplex immunoassays performed as flow-through chemiluminescence microarrays, using the example of a small molecule microarray for the simultaneous detection of 13 antibiotics in milk. By this means, we suggest to accept multianalyte immunoassays as confirmatory methods as well, to benefit from the advantages of a fast automated method that does not need any pretreatment of the sample. The presented microarray chip is regenerable, so an internal calibration is implemented. Therefore, the analytical results are highly precise, combined with low costs (the aim for commercialization is less than 1 € per analyte per sample, this is significantly less than HPLC-MS).

Challenges in the analysis of multiple mycotoxins

The problems associated with different groups or ‘families’ of mycotoxins have been known for some time, and for many years certain groups of mycotoxins have been known to co-occur in commodities and foods. Until fairly recently commodities and foods were analysed for individual toxins or groups of related toxins and attempts to measure multiple groups of toxins required significant investments in terms of time, effort, and expense. Analytical technologies using both the instrument-intensive techniques, such as mass spectrometry, and screening techniques, such as immunoassays, have progressed significantly in recent years. This has led to the proliferation of techniques capable of detecting multiple groups of mycotoxins using a variety of approaches. Despite considerable progress, the challenges for routine monitoring of multiple toxins continue. Certain of these challenges, such as the need for co-extraction of multiple analytes with widely different polarities and the potential for carry-over of matrix components that can influence the results, are independent of the analytical technique (MS or immunoassay) used. Because of the wide variety of analytical platforms used for multi-toxin analysis, there are also specific challenges that arise amongst the analytical platforms. We showed that chromatographic methods with optical detection for aflatoxins maintain stable response factors over rather long periods. This offers the potential to reduce the analytical burden, provided the use of a single signal receives general acceptance once shown in practise as working approach. This must however be verified by a larger community of laboratories. For immunosensors the arising challenges include the reusability of sensors and, for chromatography-based assays they include the selection of appropriate calibration systems. In this article we seek to further describe the challenges associated with multi-toxin analysis and articulate how such challenges have recently been addressed.

Mycotoxin Determination in Foods Using Advanced Sensors Based on Antibodies or Aptamers

Mycotoxin contamination threatens health and life of humans and animals throughout the food supply chains. Many of the mycotoxins have been proven to be carcinogens, teratogens and mutagens. The reliable and sensitive sensing methods are requested to monitor mycotoxin contamination. Advanced sensors based on antibodies or aptamers boast the advantages of high sensitivity and rapidity, and have been used in the mycotoxin sensing. These sensors are miniaturized, thereby lowering costs, and are applicable to high-throughput modes. In this work, the latest developments in sensing strategies for mycotoxin determination were critically discussed. Optical and electrochemical sensing modes were compared. The sensing methods for single mycotoxin or multiple mycotoxins in food samples were reviewed, along with the challenges and the future of antibody or aptamer-based sensors. This work might promote academic studies and industrial applications for mycotoxin sensing.

Mycotoxin detection

Mycotoxins are toxic metabolites of certain fungi that growth on a variety of crops, pre-harvest, during and post-harvest. Because of their toxicity, maximum admissible levels of mycotoxins are regulated worldwide and monitoring of their occurrence in several commodities is mandatory for assuring food safety and consumers' health protection. Analytical methods for mycotoxins include immunochemical-based techniques that principally apply for routinely controls and rapid, on-site detection, and chromatographic-based techniques that provide sensitive, accurate and selective determination of known mycotoxins, besides identification of new or modified compounds through tandem mass spectrometric detectors.

A universal multi-wavelength fluorescence polarization immunoassay for multiplexed detection of mycotoxins in maize

Multi-analyte immunoassays have attracted increasing attention due to their short assay times, low sample consumption, and reduced detection costs per assay. In this work, we describe a homologous and high-throughput multi-wavelength fluorescence polarization immunoassay (MWFPIA) for the multiplexed detection of mycotoxins. Three typical Fusarium mycotoxins, deoxynivalenol (DON), T-2 toxin and fumonisin B1 (FB1), were labeled with different dyes. Tracers and specific monoclonal antibodies (mAbs) were employed in the MWFPIA to simultaneously detect the three mycotoxins. Under optimal conditions, the limits of detection using MWFPIA were 242.0 μg kg(-1) for DON, 17.8 μg kg(-1) for T-2 toxin and 331.5 μg kg(-1) for FB1, providing sufficient sensitivity to meet the action levels of these three contaminants in maize as set by the European Union. The use of a methanol/water (2:3, v/v) mixture for sample pretreatment allowed recoveries ranging from 76.5-106.3%, with coefficients of variation less than 21.7%. The total time of analysis, including sample preparation, was less than 30 min. Twenty naturally contaminated maize samples were tested using MWFPIA and HPLC-MS/MS, with correlation coefficients (R(2)) of 0.97 for DON and 0.99 for FB1. By changing the targets of interest, homologous MWFPIA, a method with high sensitivity, a simple procedure and a short analysis time, can easily be extended to other chemical contaminants. Thus, MWFPIA represents a versatile strategy for food safety analysis.

Regeneration of recombinant antigen microarrays for the automated monitoring of antibodies against zoonotic pathogens in swine sera

The ability to regenerate immobilized proteins like recombinant antigens (rAgs) on surfaces is an unsolved problem for flow-based immunoassays on microarray analysis systems. The regeneration on microarray chip surfaces is achieved by changing the protein structures and desorption of antibodies. Afterwards, reactivation of immobilized protein antigens is necessary for reconstitution processes. Any backfolding should be managed in a way that antibodies are able to detect the protein antigens in the next measurement cycle. The regeneration of rAg microarrays was examined for the first time on the MCR3 flow-based chemiluminescence (CL) microarray analysis platform. The aim was to reuse rAg microarray chips in order to reduce the screening effort and costs. An antibody capturing format was used to detect antibodies against zoonotic pathogens in sera of slaughtered pigs. Different denaturation and reactivation buffers were tested. Acidic glycine-SDS buffer (pH 2.5) and 8 M guanidinium hydrochloride showed the best results in respect of denaturation efficiencies. The highest CL signals after regeneration were achieved with a carbonate buffer containing 10 mM DTT and 0.1% BSA for reactivation. Antibodies against Yersinia spp. and hepatitis E virus (HEV) were detected in swine sera on one immunochip over 4 days and 25 measurement cycles. Each cycle took 10 min for detection and regeneration. By using the rAg microarray chip, a fast and automated screening of antibodies against pathogens in sera of slaughtered pigs would be possible for zoonosis monitoring.

Controlled growth of immunogold for amplified optical detection of aflatoxin B1

A simple, sensitive and cost-effective method for the analysis of the mycotoxin aflatoxin B1 (AFB1) has been established based on controlled growth of immunogold.

Rapid and simultaneous detection of ricin, staphylococcal enterotoxin B and saxitoxin by chemiluminescence-based microarray immunoassay

Simultaneous detection of proteotoxins, ricin and SEB, and small toxin, STX, on a chemiluminescence-based microarray using anti-idiotypic antibody for STX.

Developments in mycotoxin analysis: an update for 2012-2013

This review highlights developments in mycotoxin analysis and sampling over a period between mid-2012 and mid-2013. It covers the major mycotoxins: aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone. A wide range of analytical methods for mycotoxin determination in food and feed were developed last year, in particular immunochemical methods and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)-based methods. After a section on sampling and sample preparation, due to the rapid spread and developments in the field of LC-MS/MS multimycotoxin methods, a separate section has been devoted to this area of research. It is followed by a section on mycotoxins in botanicals and spices, before continuing with the format of previous reviews in this series with dedicated sections on method developments for the individual mycotoxins.

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.