Selective Sample Cleanup by Reusable Sol−Gel Immunoaffinity Columns for Determination of Deoxynivalenol in Food and Feed Samples

Male reproductive toxicity of zearalenone-meta-analysis with mechanism review

Zearalenone (ZEA) is an oestrogen-like mycotoxin produced by Fusarium fungi, which has a considerable impact on human and animal health and results in substantial economic losses worldwide. This study aimed to demonstrate the reproductive injury induced by ZEA in rodents. We conducted a rigorous meta-analysis of the related literature via PubMed, Embase, and Web of Science. The scope of the study includes the following: development of reproductive organs, serum testosterone, oestradiol, and luteinizing hormone (LH) levels; parameters of Leydig cells; and parameters of semen. In total, 19 articles were reviewed. Compared with the control group, the increased relative epididymis weight, increased serum oestradiol level, and decreased LH levels in the prenatally exposed group were observed. In pubertal and adult rodents, the relative testicular weight, serum oestradiol level, Leydig cell number, and percentage of ST (+) Leydig cells decreased under ZEA exposure. In rodents at all ages, decreased serum testosterone level, sperm concentration, sperm motility rate, and increased serum deformity rate were observed in exposed groups compared with control groups. Although subgroup analysis failed to identify a clear dose-response relationship between ZEA exposure and reproductive system damage in male rodents, we still managed to confirm that zearalenone could decrease the serum testosterone level at the dosage of 50 mg/kg*day, 1.4 mg/kg*day, and 84 mg/kg*day, of prenatal, pubertal, and mature rodents respectively; pubertal zearalenone exposure impairs the quality and quantity of sperms of rodents at the dosage of 1.4 mg/kg*day and mature zearalenone exposure has the same effect at the dosage of 84 mg/kg*day. In conclusion, we found that ZEA exposure can cause considerable damage to the reproductive system of rodents of all ages. While the exact underlying mechanism of ZEA-induced toxicity in the reproductive system remains largely unknown, the theories of oestrogen-like effects and oxidative stress damage are promising.

Immunoaffinity Extraction and Alternative Approaches for the Analysis of Toxins in Environmental, Food or Biological Matrices

The evolution of instrumentation in terms of separation and detection allowed a real improvement of the sensitivity and analysis time. However, the analysis of ultra-traces of toxins in complex samples requires often a step of purification and even preconcentration before their chromatographic analysis. Therefore, immunoaffinity sorbents based on specific antibodies thus providing a molecular recognition mechanism appear as powerful tools for the selective extraction of a target molecule and its structural analogs to obtain more reliable and sensitive quantitative analysis in environmental, food or biological matrices. This review focuses on immunosorbents that have proven their efficiency in selectively extracting various types of toxins of various sizes (from small mycotoxins to large proteins) and physicochemical properties. Immunosorbents are now commercially available, and their use has been validated for numerous applications. The wide variety of samples to be analyzed, as well as extraction conditions and their impact on extraction yields, is discussed. In addition, their potential for purification and thus suppression of matrix effects, responsible for quantification problems especially in mass spectrometry, is presented. Due to their similar properties, molecularly imprinted polymers and aptamer-based sorbents that appear to be an interesting alternative to antibodies are also briefly addressed by comparing their potential with that of immunosorbents.

Novel monoclonal antibody-based immunochromatographic strip for detecting citrinin in fruit from Zhejiang province, China

Citrinin (CIT) is a hepato-nephrotoxic fungal metabolite produced by the genera Penicillium, Aspergillus and Monascu. There is an increasing demand for rapid and economical methods for detection CIT residues in fruit. In this study, we developed an immunochromatographic strip (ICS) for detection of citrinin (CIT) residues in fruit for the first time. Anti-CIT monoclonal antibody (McAb) 2B9 was prepared, with a binding affinity of 9.39 × 108 L/moL. Conjugates CIT-BSA and McAb 2B9 were used to develop the ICS which could be completed in 5 min, with the detection limit of 50 ng/mL and no cross reactivity with other mycotoxins. Analysis of CIT in 64 fruit samples revealed that data obtained from the ICS test were in good agreement with indirect competitive enzyme-linked immunosorbent assays (ic-ELISAs) and high performance liquid chromatography (HPLC). This result demonstrated that the ICS test could be used as a rapid, reliable, cost-effective and user-friendly qualitative tool for detection of CIT residues on-site.

Development of an immunochromatographic strip test for the rapid detection of zearalenone in wheat from Jiangsu province, China

A colloidal gold (ICS) test was developed for rapid detection of zearalenone (ZEN) in wheat samples. The mAb against ZEN was prepared in our laboratory and labelled with colloidal gold as a probe for the ICS test. The conditions were optimized and 30 nm colloidal gold nanoparticles were chosen for optimal performance. Millipore 135 was chosen as the NC membrane for its level of sensitivity. The optimum amount of coated antigen ZEN-OVA and anti-ZEN mAb was 0.5 mg/mL and 8 μg/mL, respectively. The ICS test, which has a detection limit of 15 ng/mL for ZEN, could be completed in 5 min. Analysis of ZEN in 202 wheat samples over three consecutive years revealed that data obtained from the ICS test were in a good agreement with LC-MS/MS data. This result demonstrated that the ICS test could be used as a qualitative tool to screen on-site for ZEN.

A rapid Raman detection of deoxynivalenol in agricultural products

Mycotoxin results in financial damage and considerable safety risks. In this paper, the possibility of portable Raman system-based surface-enhanced Raman scattering (SERS) for a rapid detection of deoxynivalenol (DON) a mycotoxin in cereals was investigated. Under an optimized condition, SERS analysis for pure DON solution has a wide dynamic concentration range from 10^-7M to 10^-2M with the limit of detection (LOD) down to 100nM. Density functional theory (DFT) analysis at the level of B3LYP/6-311++G(d, p) was also preformed for vibrational assignment. For practical application, the LOD of the proposed Raman method for both DON-contaminated corns and kidney beans were validated as 10^-6M and the LOD for DON-contaminated oats was 10^-4M. As a perspective, the SERS-based technology could be developed into an alternatively promising assay for on-field detection of DON residues at various cereals due to it high sensitivity and selectivity.

Occurrence and exposure assessment of multiple mycotoxins in dried fruits based on liquid chromatography-tandem mass spectrometry

A reliable analytical method based on liquid chromatography-tandem mass spectrometry was developed for simultaneous determination of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1, aflatoxin G2, ochratoxin A (OTA), deoxynivalenol, T-2 and HT-2 toxin, and zearalenone (ZEA) in various dried fruits. A simple one-step sample extraction without using clean-up cartridges made the established method less labour consuming and less expensive, while optimisation of the several important MS/MS parameters, i.e. the scan time and run segments, ensured its sensitivity and selectivity. After careful validation of the method by determining the linearity (R2>0.99), recovery (77.8-115.9%), precision (relative standard deviation ≤19.5%) and sensitivity (limits of quantification in the range of 0.1-10 μg/kg), a survey of 125 dried fruit samples including 25 pistachios, 28 dried longans, 32 raisins and 40 dried dates randomly collected from different markets in Shanghai, China, was performed. Results revealed that 32.0% of samples were contaminated with different mycotoxins, among which, OTA was the most frequent contaminant with the incidence of 29.6% attaining the concentration levels in the range of 0.4-212.6 μg/kg. ZEA was positively found in 2 pistachio samples with the concentrations of 84.9 μg/kg and 426.9 μg/kg. Trace amounts of AFB1 (0.8 μg/kg) and AFB2 (0.2 μg/kg) were also observed in one pistachio sample and one dried longan sample, respectively. To the best of our knowledge, this is the first report to reveal the real situations of mycotoxin contaminations in various dried fruits in China.

Preparation and application of an immunoaffinity column based on an antibody with strong affinity and packing material with good stability

This article describes the production of an anti-citrinin antibody that showed a high affinity constant (Ka) of 6.28 × 10⁹ and good tolerance to organic solvent and low pH, the synthesis of a Cu (II)-embedded polymer that showed strong binding with this antibody and the preparation of packing material for an immunoaffinity column (IAC) that show good stability. Most of the IACs reported either use harsh elution conditions and are used only once or use gentle elution conditions and are reused many times. Here, through the combined use of a strong-affinity antibody and packing material with good stability, high recoveries during clean-up and yet simultaneously good stability of the IAC were successfully achieved. Under optimised conditions of 80% methanol (pH 3), the IACs were used to clean-up the extracts of Monascus colour and red yeast rice samples, followed by HPLC detection. The recoveries of citrinin from spiked samples at levels of 50-200 μg kg⁻¹ were in the range of 84-97%.

Mixed immunoassay design for multiple chemical residues detection

In this research, a mixed immunoassay design for multiple chemical residues detection based on combined reverse competitive enzyme-linked immunosorbent assay (ELISA) procedure was developed. This method integrated two reverse ELISA reactions in one assay by labeling horseradish peroxidase to deoxynivalenol (DON) and orbifloxacin. Within this method, IC50 of the two mAbs for each analyte we produced ranged from 23~68 ng mL(-1) for DONs and 4.1~49 ng mL(-1) for quinolones (QNs). The limit of detection measured by IC10 was achieved at 0.45-1.3 ng mL(-1) for DONs and 0.59-6.9 ng mL(-1) for QNs, which was lower than the maximum residue levels. Recoveries in negative samples spiked at concentrations of 100, 200, and 500 ng mL(-1) ranged from 91.3 to 102.2 % for DONs and 88.7-98.05 % for QNs with relative standard deviation less than 9.88 and 12.67 %. The results demonstrated that this developed immunoassay was suitable for screening of low molecular weight contaminants.

Determination of deoxynivalenol in cereals by immunoaffinity clean-up and ultra-high performance liquid chromatography tandem mass spectrometry

An immunoaffinity column (IAC) was prepared with a new deoxynivalenol (DON) monoclonal antibody and used as a clean-up tool before ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) analysis of DON in cereals. The developed IAC clean-up method showed high recoveries for DON. They ranged from 61% to 103% in wheat, rice, and millet with intra-day and inter-day variations below 19% and 17%, respectively. The column capacity was 2.86μg DON per mL of gel, and it maintained above 0.68μg/mL of gel after 10 cycles of usage at 2 days intervals. The limit of detection (LOD) and limit of quantification (LOQ) were 0.3 and 0.8μg/kg, respectively. Twenty-one out of 40 analyzed commercial cereal samples were positive at DON concentrations from 7 to 534μg/kg.

New strategies in sample clean-up for mycotoxin analysis

So far, solid phase extraction, the use of MycoSep columns and immunoaffinity chromatography are the most common clean-up methods in mycotoxin analysis. Among these methods, immunoaffinity chromatography offers the highest selectivity and therefore the highest efficiency in removing interfering matrix compounds and enriching the analyte. Common immunoaffinity columns are prepared by covalently binding the antibodies to a solid support material which, due to the harsh conditions applied, frequently lowers their affinity for the antigen. The review article presents new strategies which have been developed to overcome this problem: sol-gel immunoaffinity chromatography, immuno-ultrafiltration, the use of aptamers as selective ligands and the application of molecularly imprinted polymers. The present paper covers the principles as well as the application of these approaches for sample clean-up in mycotoxin analysis.

Biosensors for mycotoxin analysis: recent developments and future prospects

The toxicity and prevalence of mycotoxins in commodities and foods has necessitated the development of rapid methods in order to ensure the protection of human food and animal feed supplies. Testing for mycotoxins can be accomplished by many techniques that range from determinative tests in which the presence of the toxin is confirmed, to presumptive tests in which the presence of the toxin is inferred from the presence of markers. This review focuses on tests that fall into a third category, namely indirect assays, where the presence of the toxin is established by it's interaction with an intermediary. Such intermediaries include biological materials that bind mycotoxins, such as antibodies, as well as synthetic materials such as polymers and man-made peptides. The diversity of assays within this category is extraordinary and includes assays based upon traditional microwell formats, microbeads, membranes, electrodes, wave-guides, and solution-phase assays. The microbead format includes platforms as diverse as flow injection immunoassays, tandem column immunoassays, and immunoaffinity columns. The membrane-based formats include flow-through as well as lateral-flow assays. The electrode-based formats incorporate miniaturised immunoassays with electrochemical endpoints. The wave-guide-based devices include formats such as surface plasmon resonance, and fluorescence array biosensors, and the solution phase formats include homogeneous assays such as fluorescence polarisation immunoassay. The breadth of technologies brought to bear upon solving the need for rapid, accurate, detection of mycotoxins is impressive and includes technologies currently available commercially and those which appear poised to enter the marketplace.

An overview of conventional and emerging analytical methods for the determination of mycotoxins

Mycotoxins are a group of compounds produced by various fungi and excreted into the matrices on which they grow, often food intended for human consumption or animal feed. The high toxicity and carcinogenicity of these compounds and their ability to cause various pathological conditions has led to widespread screening of foods and feeds potentially polluted with them. Maximum permissible levels in different matrices have also been established for some toxins. As these are quite low, analytical methods for determination of mycotoxins have to be both sensitive and specific. In addition, an appropriate sample preparation and pre-concentration method is needed to isolate analytes from rather complicated samples. In this article, an overview of methods for analysis and sample preparation published in the last ten years is given for the most often encountered mycotoxins in different samples, mainly in food. Special emphasis is on liquid chromatography with fluorescence and mass spectrometric detection, while in the field of sample preparation various solid-phase extraction approaches are discussed. However, an overview of other analytical and sample preparation methods less often used is also given. Finally, different matrices where mycotoxins have to be determined are discussed with the emphasis on their specific characteristics important for the analysis (human food and beverages, animal feed, biological samples, environmental samples). Various issues important for accurate qualitative and quantitative analyses are critically discussed: sampling and choice of representative sample, sample preparation and possible bias associated with it, specificity of the analytical method and critical evaluation of results.

Multidimensional liquid phase separations for mass spectrometry

Large part of the current research in biology, medicine, and biotechnology depends on the analysis of DNA (genomics), proteins (proteomics), or metabolites (metabolomics). The advances in biotechnology also command development of adequate analytical instrumentation capable to analyze minute amounts of samples. The analysis of the content of single cells may serve as an example of ultimate analytical applications. Most of the separation techniques have been developed in the last three decades and alternative approaches are being investigated. At present, the main protocols for analyses of complex mixtures include 2-DE (IEF) followed by electrophoresis in SDS polyacrylamide gel (SDS-PAGE) and chromatographic techniques. Information-rich techniques such as MS and NMR are essential for the identification and structure analysis of the analyzed compounds. High resolution separation of the individual sample components is often a prerequisite for success. High resolution proteomic analysis in the majority of laboratories still relies on the time consuming and laborious offline methods. This review highlights some of the important aspects of 2-D separations including microfluidics.