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

A review of biomolecules conjugated lanthanide up-conversion nanoparticles-based fluorescence probes in food safety and quality monitoring applications

Upconversion nanoparticles (UCNPs) are known to possess unique characteristics, which allow them to overcome a number of issues that plague traditional fluorescence probes. UCNPs have been employed in a variety of applications, but it is arguably in the realm of optical sensors where they have shown the most promise. Biomolecule conjugated UCNPs-based fluorescence probes have been developed to detect and quantify a wide range of analytes, from metal ions to biomolecules, with great specificity and sensitivity. In this review, we have given much emphasis on the recent trends and progress in the preparation strategies of bioconjugated UCNPs and their potential application as fluorescence sensors in the trace level detection of food industry-based toxicants and adulterants. The paper discusses the preparation and functionalisation strategies of commonly used biomolecules over the surface of UCNPs. The use of different sensing strategies namely heterogenous and homogenous assays, underlying fluorescence mechanisms in the detection process of food adulterants are summarized in detail. This review might set a precedent for future multidisciplinary research including the development of novel biomolecules conjugated UCNPs for potential applications in food science and technology.

Co-Occurrence of Aflatoxin B1, Zearalenone and Ochratoxin A in Feed and Feed Materials in Central Italy from 2018 to 2022

Mycotoxin contamination of feed and feed materials represent a serious health hazard. This study details the occurrence of aflatoxin B1 (AFB1), zearalenone (ZEN) and ochratoxin A (OTA) in 826 feed and 617 feed material samples, collected in two Italian Regions (Umbria and Marche) from 2018 to 2022 analyzed using a UPLC-FLD platform. The developed method was validated and accredited (ISO/IEC 17025) with satisfactory accuracy and precision data obtained in repeatability and intralaboratory reproducibility conditions. Feed had a higher incidence of contaminated samples (26%) with respect to feed materials (6%). AFB1 was found up to 0.1045 mg/kg in cattle feeds and 0.1234 mg/kg in maize; ZEN was detected up to 6.420 mg/kg in sheep feed while OTA was rarely reported and in lower concentrations (up to 0.085 mg/kg). Co-contamination of at least two mycotoxins was reported in 0.8% of the analyzed samples. The incidence of above maximum content/guidance level samples was 2% for feed and feed materials while almost 3-fold-higher for maize (5.8%) suggesting how mycotoxin contamination can affect some matrices more than others. Obtained data can be useful to improve official monitoring plans and therefore further raise awareness of this issue between agriculture stakeholders, healthcare entities and non-professionals.

Innovative approaches for mycotoxin detection in various food categories

Mycotoxins (MTs), produced by filamentous fungi, represent a severe hazard to the health of humans and food safety, affecting the quality of various agricultural products. They can contaminate a wide range of foods, during any processing phase before or after harvest. Animals and humans who consume MTs-contaminated food or feed may experience acute or chronic poisoning, which may result in serious pathological consequences. Accordingly, developing rapid, easy, and accurate methods of MTs detection in food becomes highly urgent and critical as a quality control and to guarantee food safety and lower health hazards. In this review, we highlighted and discussed innovative approaches like biosensors, fluorescent polarization, capillary electrophoresis, infrared spectroscopy, and electronic noses for MT identification pointing out current challenges and future directions. The limitations, current challenges, and future directions of conventional detection methods versus innovative methods have also been highlighted and discussed.

Type B Trichothecenes in Cereal Grains and Their Products: Recent Advances on Occurrence, Toxicology, Analysis and Post-Harvest Decontamination Strategies

Type B trichothecenes (deoxynivalenol, nivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol) and deoxynivalenol-3-glucoside (DON-3G) are secondary toxic metabolites produced mainly by mycotoxigenic Fusarium fungi and have been recognized as natural contaminants in cereals and cereal-based foods. The latest studies have proven the various negative effects of type B trichothecenes on human health. Due to the widespread occurrence of Fusarium species, contamination by these mycotoxins has become an important aspect for public health and agro-food systems worldwide. Hence, their monitoring and surveillance in various foods have received a significant deal of attention in recent years. In this review, an up-to-date overview of the occurrence profile of major type B trichothecenes and DON-3G in cereal grains and their toxicological implications are outlined. Furthermore, current trends in analytical methodologies for their determination are overviewed. This review also covers the factors affecting the production of these mycotoxins, as well as the management strategies currently employed to mitigate their contamination in foods. Information presented in this review provides good insight into the progress that has been achieved in the last years for monitoring type B trichothecenes and DON-3G, and also would help the researchers in their further investigations on metabolic pathway analysis and toxicological studies of these Fusarium mycotoxins.

Evaluating the Performance of Lateral Flow Devices for Total Aflatoxins with Special Emphasis on Their Robustness under Sub-Saharan Conditions

As aflatoxins are a global risk for humans and animals, testing methods for rapid on-site screening are increasingly needed alongside the standard analytical laboratory tools. In the presented study, lateral flow devices (LFDs) for rapid total aflatoxin screening were thoroughly investigated with respect to their matrix effects, cross-reactivity, their performance under harsh conditions in Sub-Saharan Africa (SSA), and their stability, as well as when compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS). To analyze the matrix effects, qualitative test kits offering a certain cutoff level were used to screen different nut samples. In addition, these tests were challenged on their cross-reactivity with 230 fungal toxins and metabolites. Furthermore, the resulting measurements performed under harsh tropical conditions (up to 38.4 °C and 91% relative humidity) in SSA, specifically Burkina Faso and Mozambique, were compared with the results from a well-established and validated LC-MS/MS-based reference method. The comparison of the on-site LFD results with the reference method showed a good agreement: 86.4% agreement, 11.8% non-agreement, and 1.8% invalid test results. To test the robustness of the cutoff tests, short- and long-term stability testing was carried out in Mozambique and Nigeria. For both experiments, no loss of test performance could be determined. Finally, a subset of African corn samples was shipped to Austria and analyzed under laboratory conditions using semiquantitative aflatoxin tests. A good correlation was found between the rapid strip tests and the LC-MS/MS reference method. Overall, the evaluated LFDs showed satisfying results regarding their cross-reactivity, matrix effects, stability, and robustness.

Binding Characteristic of Various Antibody Formats Against Aflatoxins

The application of recombinant antibodies for the analysis of foods and food contaminants is now a major focus, given their capacity to be engineered to tailor their specificity, enhance their stability, and modify their structural formats to fit the desired analytical platform. In this study, human scFv antibody fragments generated against aflatoxin B1 (AFB1) were selected as the model antibody to explore the effect of antibody formats on their binding activity and to evaluate their potential use as immunoreagents for food contaminant analysis. Four human scFv antibody fragments against aflatoxin B1 (AFB1), previously isolated and engineered by chain shuffling, were converted into various formats, that is, scFv-AP fusions, scFv-Fc, and whole IgG molecules. The result indicated that the effects of the antibody format on the binding property varied, depending on the sequence of scFv. For all of the scFv clones, the scFv-AP fusion format showed the highest sensitivity by competitive ELISA, while the effects on the binding activity after conversion to scFv-Fc or IgG format varied, depending on the amino acid sequence of the antibodies. The sAFH-3e3 antibodies that showed the best performance by competitive ELISA were selected for further investigation. The sAFH-3e3 was converted to the scFv-GFP format and tested by fluorescence-linked immunosorbent assay (FLISA), which showed that its binding property was equivalent to those of scFv-Fc and IgG formats. The potential applications of the sAFH-3e3 in a rapid test kit format based on ELISA (scFv-AP) and in a lateral flow immunochromatography assay (LFIA) (IgG) were demonstrated. A comparison of methods for the extraction of AFB1 from matrices for use with these assay formats indicated that PBS and TBST are better than 70% methanol.

1 An HPLC-MS/MS Method Using a Multitoxin Clean-up Column for Analysis of Seven Mycotoxins in Aquafeeds

BACKGROUND

In Guangdong Province of China, the climate here is very wet, so there are many different fungus living in the aquatic feeds, which produce mycotoxins. These compounds contaminate agriculture products world-wide and represent a great threat to human health. It is necessary to determine their contamination level in aquatic feeds.

OBJECTIVE

A high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method was developed for the quantitative analysis of aflatoxin B1, aflatoxin M1, T-2 toxin, HT-2 toxin, deoxynivalenol, ochratoxin, and zearalenone in the fish and shrimp feed.

METHODS

Samples were extracted with acetonitrile-water (V: V = 3:1), and degreased with acetonitrile-saturated hexane. Such obtained extract was cleaned up with a multitoxin column. The target compounds were separated on a C18 chromatographic column and analyzed simultaneously by electrospray ionization mass spectrometry in both positive or negative ion mode. Detected compounds were quantified by using the matrix-matched external standard method.

RESULTS

Under the optimized conditions, good linearities for the analytes in corresponding concentration range were obtained with correlation coefficients (r2) higher than 0.9948. LOD ranged from 1.83 to 12.63 μg/kg, and LOQ ranged from 5.49 to 37.89 μg/kg. Average recoveries for the target mycotoxins at three spiked levels ranged from 80.5% to 116.5% with RSD ranging from 2.4% to 10.4%. 23 real aquafeed samples were determined by this method, and 7 kinds of toxins were all detected.

CONCLUSIONS

Obtained results showed that developed method could be successfully applied for the simultaneous determination of mycotoxins in aquatic feeds.

Integrated Mycotoxin Management System in the Feed Supply Chain: Innovative Approaches

Exposure to mycotoxins is a worldwide concern as their occurrence is unavoidable and varies among geographical regions. Mycotoxins can affect the performance and quality of livestock production and act as carriers putting human health at risk. Feed can be contaminated by various fungal species, and mycotoxins co-occurrence, and modified and emerging mycotoxins are at the centre of modern mycotoxin research. Preventing mould and mycotoxin contamination is almost impossible; it is necessary for producers to implement a comprehensive mycotoxin management program to moderate these risks along the animal feed supply chain in an HACCP perspective. The objective of this paper is to suggest an innovative integrated system for handling mycotoxins in the feed chain, with an emphasis on novel strategies for mycotoxin control. Specific and selected technologies, such as nanotechnologies, and management protocols are reported as promising and sustainable options for implementing mycotoxins control, prevention, and management. Further research should be concentrated on methods to determine multi-contaminated samples, and emerging and modified mycotoxins.

Survey of aflatoxins and ochratoxin A contamination in spices by HPLC-based method in Shiraz, Southern of Iran

Among food and agricultural products, spices play important roles in the diets of millions of people worldwide. These products may be colonized by fungi genus and subsequently mycotoxin production. Due to the large demand and supply of spice for cooking, preservative effects, or medicine purpose, it is essential that further investigation is designed to examine mycotoxins in spice. In the present study, the possible contamination of spices by aflatoxins (AFTs) and ochratoxin A (OTA) were analyzed. A total of 80 spice samples (curry, sumac, ginger, and saffron) were purchased and cultured on appropriate medium. Simultaneously mycotoxins from spices were extracted with immunoaffinity columns (IAC), and the occurrence of AFTs (B1 + B2 + G1 + G2) and OTA was then determined using high-performance liquid chromatography (HPLC) with a fluorescence detector (FD). The results depicted that 62 (77.5%) and 58 (72.5%) spice samples were contaminated with AFTs and OTA, respectively. Out of the 80 analyzed spices samples, the mean concentration of AFTs and OTA was higher in the curry samples. Among spices that contaminated with mycotoxins, 5 (6.25%) and 2 (10%) of the samples were above the acceptable limit of AFTs (≥ 10 μg/kg) and OTA (≥ 15 μg/kg), respectively. Aspergillus species were the predominant species isolated, followed by Penicillium, and finally Mucor species.Among the examined samples, only few curry samples were contaminated with mycotoxins above acceptable limit. Despite this low level of contamination, this spice is used daily in the cuisine of this region of the world, and consequently, even the small amount of these heat stable toxins for a long time may cause many adverse effects. Hence, it is recommended to monitor the toxicogenous fungi contamination and level of mycotoxins in the spices.

Biosensing based on upconversion nanoparticles for food quality and safety applications

Food safety and quality regulations inevitably call for sensitive and accurate analytical methods to detect harmful contaminants in food and to ensure safe food for the consumer. Both novel and well-established biorecognition elements, together with different transduction schemes, enable the simple and rapid analysis of various food contaminants. Upconversion nanoparticles (UCNPs) are inorganic nanocrystals that convert near-infrared light into shorter wavelength emission. This unique photophysical feature, along with narrow emission bandwidths and large anti-Stokes shift, render UCNPs excellent optical labels for biosensing because they can be detected without optical background interferences from the sample matrix. In this review, we show how this exciting technique has evolved into biosensing platforms for food quality and safety monitoring and highlight recent applications in the field.

Aspergillus derived mycotoxins in food and the environment: Prevalence, detection, and toxicity

Aspergillus species are the paramount ubiquitous fungi that contaminate various food substrates and produce biochemicals known as mycotoxins. Aflatoxins (AFTs), ochratoxin A (OTA), patulin (PAT), citrinin (CIT), aflatrem (AT), secalonic acids (SA), cyclopiazonic acid (CPA), terrein (TR), sterigmatocystin (ST) and gliotoxin (GT), and other toxins produced by species of Aspergillus plays a major role in food and human health. Mycotoxins exhibited wide range of toxicity to the humans and animal models even at nanomolar (nM) concentration. Consumption of detrimental mycotoxins adulterated foodstuffs affects human and animal health even trace amounts. Bioaerosols consisting of spores and hyphal fragments are active elicitors of bronchial irritation and allergy, and challenging to the public health. Aspergillus is the furthermost predominant environmental contaminant unswervingly defile lives with a 40-90 % mortality risk in patients with conceded immunity. Genomics, proteomics, transcriptomics, and metabolomics approaches useful for mycotoxins' detection which are expensive. Antibody based detection of toxins chemotypes may result in cross-reactivity and uncertainty. Aptamers (APT) are single stranded DNA (ssDNA/RNA), are specifically binds to the target molecules can be generated by systematic evolution of ligands through exponential enrichment (SELEX). APT are fast, sensitive, simple, in-expensive, and field-deployable rapid point of care (POC) detection of toxins, and a better alternative to antibodies.

Optimum cold plasma generating device for treatment of Aspergillus flavus from nuts surface

The objective of this research is to avail an optimum cold plasma generating device for inactivating Aspergillus flavus from nuts surface. For this purpose, a variety of tests were carried out using three applicable plasma generating devices such as atmospheric pressure capacitive coupled plasma (AP-CCP), direct current diode plasma (DC-DP), and inductively coupled plasma (ICP) for different values of input power, pressure, and irradiation time, using Argon gas. The experimental results were achieved upon performing irradiation of sample pistachio nuts by the aforementioned three devices. Finally, after data analysis based on two factors of toxin inactivation amount and cost feasibility for large scale industrial applications, the AP-CCP device was found to be as an optimum device with an acceptable 4 Logs fungi reduction. However, on the basis of single factor, i.e. toxin reduction rate, the DC-DP device works better with a highest fungi reduction rate of 5 Logs, using Argon in 1 Torr vacuum pressure, 300 W and 20 min irradiation.

Analysis of Toxigenic Fusarium Species Associated with Wheat Grain from Three Regions of Russia: Volga, Ural, and West Siberia

Wheat grains collected in three regions of Russia—Volga, Ural, and West Siberia—were analyzed for triangulation of methods in analysis of toxigenic Fusarium species. The presence of fungi and quantitative content of their biomass were detected by using various analytical methods, including a mycological and immunochemical methods, and quantitative PCR. Additionally, an enzyme-linked immunosorbent assay and high-performance liquid chromatography with tandem mass spectrometry were applied for determination of mycotoxins. Regional differences were found regarding the contamination of wheat grain by Fusarium fungi and their toxins. The most important observation was the detection of F. graminearum in the Ural and West Siberian regions, where this pathogen had not been found previously. A maximum damaged grains by F. graminearum and F. sporotrichioides was found in the grain samples from West Siberia. The DNA of F. graminearum was detected in 19.2% and DNA of F. sporotrichioides was found in 84.1% of the analyzed grain samples. The amount of Fusarium antigens in the grain samples from the West Siberian region was 7–8 times higher than in the grain samples from the other two regions. Significant contamination of the grain with deoxynivalenol and T-2/HT-2 toxins (maximum contents were 2239 ppb and 199 ppb, respectively) was detected in the West Siberian region.

A monoclonal antibody-based indirect competitive enzyme-linked immunosorbent assay for flubendiamide detection

Flubendiamide (FD), the first commercial phthalic acid diamide that targets insect ryanodine receptor (RyRs), has played an important role in pest management. With its extensive worldwide application, a rapid and convenient method to detect its existence in the environment is necessary. In this study, an indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed to analyse FD residue on environmental and food samples. The established icELISA showed a half maximal inhibition concentration (IC₅₀) of 17.25 µg L^-1, with a working range of 4.06-103.59 µg L^-1 for FD, and showed no cross-reactivity with chlorantraniliprole, cyantraniliprole, and several FD analogues. Average FD recoveries from spinach, tap water, and soil samples were 89.3-112.3%, 93.0-102.1%, and 86.9-97.6%, respectively. Meanwhile, FD detection results of icELISA were compared with those of ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The comparable results verified that icELISA was suitable for rapid detection of FD residue in environmental and agricultural samples.

Thin Films Sensor Devices for Mycotoxins Detection in Foods: Applications and Challenges

Mycotoxins are a group of secondary metabolites produced by different species of filamentous fungi and pose serious threats to food safety due to their serious human and animal health impacts such as carcinogenic, teratogenic and hepatotoxic effects. Conventional methods for the detection of mycotoxins include gas chromatography and high-performance liquid chromatography coupled with mass spectrometry or other detectors (fluorescence or UV detection), thin layer chromatography and enzyme-linked immunosorbent assay. These techniques are generally straightforward and yield reliable results; however, they are time-consuming, require extensive preparation steps, use large-scale instruments, and consume large amounts of hazardous chemical reagents. Rapid detection of mycotoxins is becoming an increasingly important challenge for the food industry in order to effectively enforce regulations and ensure the safety of food and feed. In this sense, several studies have been done with the aim of developing strategies to detect mycotoxins using sensing devices that have high sensitivity and specificity, fast analysis, low cost and portability. The latter include the use of microarray chips, multiplex lateral flow, Surface Plasmon Resonance, Surface Enhanced Raman Scattering and biosensors using nanoparticles. In this perspective, thin film sensors have recently emerged as a good candidate technique to meet such requirements. This review summarizes the application and challenges of thin film sensor devices for detection of mycotoxins in food matrices.

Simultaneous determination of trace Aflatoxin B1 and Ochratoxin A by aptamer-based microchip capillary electrophoresis in food samples

An aptamer-based microchip capillary electrophoresis coupled with laser induced fluorescence (MCE-LIF) detection method for fast determination of Aflatoxin B₁ (AFB₁) and Ochratoxin A (OTA) was developed. Aptamers that are specific to these two mycotoxins were first hybridized with their aptamer complementary oligonucleotides. The double strand DNA that comes in contact with mycotoxin-containing environment would be unwound into separate aptamer-mycotoxin complex and aptamer complementary single strand. Different types of oligonucleotides can be separated in MCE and detected under the aid of fluorescent dye SYBR gold in LIF detection unit. Under the optimal conditions, on-chip aptamer-mycotoxin conjugates analysis was achieved within 3 min with extremely low LODs (0.026 ng/mL for AFB₁ and 0.021 ng/mL for OTA). Specificity study indicated that other major mycotoxins would not cross-react with these two aptamers, demonstrating the good selectivity of the proposed method. Quantification of trace AFB₁ and OTA in real food samples was carried out and satisfactory recoveries were obtained. It is demonstrated that this method is fast, facile and specific for Simultaneous determination of trace AFB₁ and OTA from foodstuffs.

Bioinspired recognition elements for mycotoxin sensors

Mycotoxins are low molecular weight molecules produced as secondary metabolites by filamentous fungi that can be found as natural contaminants in many foods and feeds. These toxins have been shown to have adverse effects on both human and animal health, and are the cause of significant economic losses worldwide. Sensors for mycotoxin analysis have traditionally applied elements of biological origin for the selective recognition purposes. However, since the 1970s there has been an exponential growth in the use of genetically engineered or synthetic biomimetic recognition elements that allow some of the limitations associated with the use of natural receptors for the analyses of these toxins to be circumvented. This review provides an overview of recent advances in the application of bioinspired recognition elements, including recombinant antibodies, peptides, aptamers, and molecularly imprinted polymers, to the development of sensors for mycotoxins based on different transduction elements. Graphical abstract Novel analytical methods based on bioinspired recognition elements, such as recombinant antibodies, peptides, aptamers, and molecularly imprinted polymers, can improve the detection of mycotoxins and provide better tools than their natural counterparts to ensure food safety.

A Collaborative Study: Determination of Mycotoxins in Corn, Peanut Butter, and Wheat Flour Using Stable Isotope Dilution Assay (SIDA) and Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

A collaborative study was conducted to evaluate stable isotope dilution assay (SIDA) and LC-MS/MS for the simultaneous determination of aflatoxins B₁, B₂, G₁, and G₂; deoxynivalenol; fumonisins B₁, B₂, and B₃; ochratoxin A; HT-2 toxin; T-2 toxin; and zearalenone in foods. Samples were fortified with 12 ¹³C uniformly labeled mycotoxins (¹³C-IS) corresponding to the native mycotoxins and extracted with acetonitrile/water (50:50 v/v), followed by centrifugation, filtration, and LC-MS/MS analysis. In addition to certified reference materials, the six participating laboratories analyzed corn, peanut butter, and wheat flour fortified with the 12 mycotoxins at concentrations ranging from 1.0 to 1000 ng/g. Using their available LC-MS/MS platform, each laboratory developed in-house instrumental conditions for analysis. The majority of recoveries ranged from 80 to 120% with relative standard derivations (RSDs) <20%. Greater than 90% of the average recoveries of the participating laboratories were in the range of 90-110%, with repeatability RSD_r (within laboratory) < 10% and reproducibility RSD_R (among laboratory) < 15%. All Z scores of the results of certified reference materials were between -2 and 2. Using ¹³C-IS eliminated the need for matrix-matched calibration standards for quantitation, simplified sample preparation, and achieved simultaneous identification and quantitation of multiple mycotoxins in a simple LC-MS/MS procedure.

Occurrence, Toxicity, and Analysis of Major Mycotoxins in Food

Mycotoxins are toxic secondary metabolites produced by certain filamentous fungi (molds). These low molecular weight compounds (usually less than 1000 Daltons) are naturally occurring and practically unavoidable. They can enter our food chain either directly from plant-based food components contaminated with mycotoxins or by indirect contamination from the growth of toxigenic fungi on food. Mycotoxins can accumulate in maturing corn, cereals, soybeans, sorghum, peanuts, and other food and feed crops in the field and in grain during transportation. Consumption of mycotoxin-contaminated food or feed can cause acute or chronic toxicity in human and animals. In addition to concerns over adverse effects from direct consumption of mycotoxin-contaminated foods and feeds, there is also public health concern over the potential ingestion of animal-derived food products, such as meat, milk, or eggs, containing residues or metabolites of mycotoxins. Members of three fungal genera, Aspergillus, Fusarium, and Penicillium, are the major mycotoxin producers. While over 300 mycotoxins have been identified, six (aflatoxins, trichothecenes, zearalenone, fumonisins, ochratoxins, and patulin) are regularly found in food, posing unpredictable and ongoing food safety problems worldwide. This review summarizes the toxicity of the six mycotoxins, foods commonly contaminated by one or more of them, and the current methods for detection and analysis of these mycotoxins.

Development of Methods for Determination of Aflatoxins

Aflatoxins can cause damage to the health of humans and animals. Several institutions around the world have established regulations to limit the levels of aflatoxins in food, and numerous analytical methods have been extensively developed for aflatoxin determination. This review covers the currently used analytical methods for the determination of aflatoxins in different food matrices, which includes sampling and sample preparation, sample pretreatment methods including extraction methods and purification methods of aflatoxin extracts, separation and determination methods. Validation for analysis of aflatoxins and safety considerations and precautions when doing the experiments are also discussed.

Multiplex Dipstick Immunoassay for Semiquantitative Determination of Fusarium Mycotoxins in Oat

A multiplex competitive antibody-based assay in a dipstick format for the simultaneous detection of major of Fusarium mycotoxins in oats is described. Ground oats sample is extracted with a mixture of methanol and water. Sample extract is diluted and directly analyzed by a multiplex dipstick. The test kit employs a microwell of reagents containing antibodies linked to gold particles and a dipstick made up of a nitrocellulose membrane were specific capture lines are located. In the presence of oats extract each antibody binds the corresponding mycotoxin before starting to run vertically on the dipstick in the direction of the capture lines. In 10 min red lines rise from the background on the dipstick. Results are interpreted by an optical reader measuring the ratio between each test line and a control line located on the top of the strip.

Comparison of In-Solution Biorecognition Properties of Aptamers against Ochratoxin A

Ochratoxin A (OTA) is a mycotoxin produced as a secondary metabolite by several species of Aspergillus and Penicillium and frequently found as a natural contaminant in a wide range of food commodities. Novel and robust biorecognition agents for detecting this molecule are required. Aptamers are artificial nucleic acid ligands able to bind with high affinity and specificity to a given target molecule. In the last few years, three separate research groups have selected aptamers for ochratoxin A. While each of these three families of aptamers have been incorporated into various methods for detecting OTA, it is unclear if each aptamer candidate is better suited for a particular application. Here, we perform the first head-to-head comparison of solution-based binding parameters for these groups of aptamers. Based on our results, we provide recommendations for the appropriate choice of aptamer for incorporation into solution-based biorecognition assays and applications.

Functionalized Nanofiber Meshes Enhance Immunosorbent Assays

Three-dimensional substrates with high surface-to-volume ratios and subsequently large protein binding capacities are of interest for advanced immunosorbent assays utilizing integrated microfluidics and nanosensing elements. A library of bioactive and antifouling electrospun nanofiber substrates, which are composed of high-molecular-weight poly(oxanorbornene) derivatives, is described. Specifically, a set of copolymers are synthesized from three 7-oxanorbornene monomers to create a set of water insoluble copolymers with both biotin (bioactive) and triethylene glycol (TEG) (antifouling) functionality. Porous three-dimensional nanofiber meshes are electrospun from these copolymers with the ability to specifically bind streptavidin while minimizing the nonspecific binding of other proteins. Fluorescently labeled streptavidin is used to quantify the streptavidin binding capacity of each mesh type through confocal microscopy. A simplified enzyme-linked immunosorbent assay (ELISA) is presented to assess the protein binding capabilities and detection limits of these nanofiber meshes under both static conditions (26 h) and flow conditions (1 h) for a model target protein (i.e., mouse IgG) using a horseradish peroxidase (HRP) colorimetric assay. Bioactive and antifouling nanofiber meshes outperform traditional streptavidin-coated polystyrene plates under flow, validating their use in future advanced immunosorbent assays and their compatibility with microfluidic-based biosensors.

Natural incidence of zearalenone in Croatian pig feed, urine and meat in 2014

The aim of this study was to determine the levels of zearalenone (ZEN) in different feed materials and feedstuffs for pigs, as well as in pig urine and pig meat following contaminated feed consumption. In total, 253 feed material and feedstuff samples were collected from Croatian pig farms. The results revealed the presence of ZEN in significant concentrations, the maximal being found in maize (5522 µg/kg), wheat (3366 µg/kg) and pig fattening feed (1949 µg/kg). In farms in which high feed contamination and pig hyperestrogenism were observed, samples of pig urine (n=30) and meat (n=30) were retrieved as well. The mean ZEN concentrations in pig urine and pig meat were 206±20.6 µg/L and 0.62±0.14 µg/kg, respectively. Despite high contamination of feedstuffs responsible for farmed pigs' intoxication, ZEN levels determined in pig meat were shown to be of little significance for human safety.

A multiplex chemiluminescent biosensor for type B-fumonisins and aflatoxin B1 quantitative detection in maize flour

A multiplex chemiluminescence biosensor based on a lateral flow immunoassay was developed for on-site quantitative detection of fumonisins and aflatoxin B1 in maize.

Developments in detection and determination of aflatoxins

Since the discovery of aflatoxins in the 1960s, much research has focused on detecting the toxins in contaminated food and feedstuffs in the interest of public safety. Most traditional detection methods involved lengthy culturing and/or separation techniques or analytical instrumentation and complex, multistep procedures that required destruction of samples for accurate toxin determination. With more regulations for acceptable levels of aflatoxins in place, modern analytical methods have become quite sophisticated, capable of achieving results with very high precision and accuracy, suitable for regulatory laboratories and for post-harvest sample testing in developed countries. Unfortunately, many countries around the world that are affected by the aflatoxin problem do not have ready access to high performance liquid chromatography and mass spectrometry instrumentation and require alternate, readily available and simple detection methods that may be used by small holdings farmers in developing countries. This paper presents an overview of the existing detection and/or determination methods for aflatoxins. The traditional, quantitative, chemically-based analytical strategies for detecting aflatoxins in maize and their evolution to the modern instrumentation routinely used in developed countries are reviewed. Additionally, novel, more streamlined, user-friendly and in some instances, non-destructive, methods that may be useful for semi-quantitative or qualitative, quick-screening of contaminated maize samples appropriate also for use in developing countries, are discussed.

Methods for Detection of Aflatoxins in Agricultural Food Crops

Aflatoxins are toxic carcinogenic secondary metabolites produced predominantly by two fungal species: Aspergillus flavus and Aspergillus parasiticus. These fungal species are contaminants of foodstuff as well as feeds and are responsible for aflatoxin contamination of these agro products. The toxicity and potency of aflatoxins make them the primary health hazard as well as responsible for losses associated with contaminations of processed foods and feeds. Determination of aflatoxins concentration in food stuff and feeds is thus very important. However, due to their low concentration in foods and feedstuff, analytical methods for detection and quantification of aflatoxins have to be specific, sensitive, and simple to carry out. Several methods including thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), mass spectroscopy, enzyme-linked immune-sorbent assay (ELISA), and electrochemical immunosensor, among others, have been described for detecting and quantifying aflatoxins in foods. Each of these methods has advantages and limitations in aflatoxins analysis. This review critically examines each of the methods used for detection of aflatoxins in foodstuff, highlighting the advantages and limitations of each method. Finally, a way forward for overcoming such obstacles is suggested.

Natural occurrence, analysis, and prevention of mycotoxins in fruits and their processed products

Mycotoxins are small toxic chemical products formed as the secondary metabolites by fungi that readily contaminate foods with toxins in the field or after harvest. The presence of mycotoxins, such as aflatoxins, ochratoxin A, and patulin, in fruits and their processed products is of high concern for human health due to their properties to induce severe acute and chronic toxicity at low-dose levels. Currently, a broad range of detection techniques used for practical analysis and detection of a wide spectrum of mycotoxins are available. Many analytical methods have been developed for the determination of each group of these mycotoxins in different food matrices, but new methods are still required to achieve higher sensitivity and address other challenges that are posed by these mycotoxins. Effective technologies are needed to reduce or even eliminate the presence of the mycotoxins in fruits and their processed products. Preventive measures aimed at the inhibition of mycotoxin formation in fruits and their processed products are the most effective approach. Detoxification of mycotoxins by different physical, chemical, and biological methods are less effective and sometimes restricted because of concerns of safety, possible losses in nutritional quality of the treated commodities and cost implications. This article reviewed the available information on the major mycotoxins found in foods and feeds, with an emphasis of fruits and their processed products, and the analytical methods used for their determination. Based on the current knowledge, the major strategies to prevent or even eliminate the presence of the mycotoxins in fruits and their processed products were proposed.