A mix-and-detect method based on colloidal gold immunochromatographic assay for on-site detection of zearalenone in edible oils

A pretreatment-free and eco-friendly rapid detection for mycotoxins in edible oils based on magnetic separation technique

Pretreatment steps of current rapid detection methods for mycotoxins in edible oils not only restrict detection efficiency, but also produce organic waste liquid to pollute environment. In this work, a pretreatment-free and eco-friendly rapid detection method for edible oil is established. This proposed method does not require pretreatment operation, and automated quantitative detection could be achieved by directly adding oil samples. According to polarity of target molecules, the content of surfactant in reaction solutions could be adjusted to achieve the quantitative detection of AFB1 in peanut oil and ZEN in corn oil. The recoveries are between 96.5%-110.7% with standard deviation <10.4%, and the limit of detection is 0.17 μg/kg for AFB1 and 4.91 μg/kg for ZEN. This method realizes full automation of the whole chain detection, i.e. sample in-result out, and is suitable for the on-site detection of batches of edible oils samples.

A lateral flow immunoassay method for the rapid detection of acetochlor and alachlor in vegetable oil by sensitivity enhancement by using dimethyl-β-cyclodextrin

Acetochlor is an endocrine disruptor. The acetochlor residue is strongly lipophilic and can be enriched into products during the manufacturing process. In this study, we found that dimethyl-β-cyclodextrin (DM-β-CD) solution could decrease the apparent oil/water partition coefficient (Koil-w) of acetochlor and increase the sensitivity of fluorescence lateral flow immunoassay (LFIA) for acetochlor simultaneously. Based on this, a simple LFIA method for the determination of acetochlor and alachlor residues in vegetable oil was established. The detection process only involves vortex mixing of an oil sample and dimethyl-β-cyclodextrin solution in a 1 : 3 (V/V) ratio, loading the water phase onto the immunoassay strips and reading the results. Under optimized conditions, the LOD for acetochlor in oil was 3.53 ng g-1, and the working range was 12.03-2000.00 ng g-1. The recoveries of spiked samples ranged from 91.69% ± 1.12% to 112.23% ± 2.20%. Meanwhile, the cross reactivity for alachlor was 108.22%, while for other investigated acetochlor analogues it was less than 1%, and the recoveries of alachlor were from 92.90% ± 8.03% to 113.53% ± 3.40%, which indicate that this method can detect acetochlor and alachlor simultaneously. Compared with the traditional detection method, the pre-treatment process of the proposed method is "green" and simple, and can be applied to the on-site rapid detection of acetochlor and alachlor in vegetable oil and can provide inspiration for the detection of other lipophilic pollutants.

Predicting late-onset preeclampsia by detecting ELABELA content using an immunochromatographic colloidal gold test strip: Blood ELABELA content predicts the risk of pre-eclampsia

Preeclampsia is a pregnancy disorder that seriously affects the outcome of mothers and infants and lacks effective prediction and diagnosis methods. ELABELA is the second endogenous ligand of the apelin receptor (APJ) and is associated with the pathogenesis of preeclampsia. In a previous study, the authors found that the downregulation of ELABELA expression is closely related to late-onset preeclampsia, which may be a marker for the clinical diagnosis of late-onset preeclampsia. In this study, the authors again collected 120 maternal blood samples, including 60 pregnant women with a medical diagnosis of late-onset preeclampsia. ELISA results showed that the serum ELABELA concentration in late-onset preeclampsia pregnant women (12.57 ± 7.77 ng/mL) was significantly lower than that in normal pregnant women (36.99 ± 23.58 ng/mL), which was consistent with previously reported results. Therefore, the authors used an ELABELA monoclonal antibody to label four colloidal gold nanoparticles with different diameters (15, 30, 55, and 150 nm) and developed a transverse-flow immunochromatographic band for the rapid and accurate detection of serum ELABELA levels. The strip test shows that colloidal gold with a diameter of 30 nm can be used as a good ELABELA detection marker and had more than 90% positive detection effect. Therefore, the authors hope that the colloidal gold strip with ELABELA as the diagnostic index developed by us will be popularized and applied in clinical diagnosis.

Automatic Pretreatment of Dispersive Liquid Liquid Microextraction Based on Immunomagnetic Beads Coupled with UPLC-FLD for the Determination of Zearalenone in Corn Oils

Sample pretreatment is a vital step in the detection of mycotoxins, and traditional pretreatment methods are time-consuming, labor-intensive and generate much organic waste liquid. In this work, an automatic, high-throughput and environmentally friendly pretreatment method is proposed. Immunomagnetic beads technology and dispersive liquid-liquid microextraction technology are combined, and the zearalenone in corn oils is directly purified and concentrated under the solubilization effects of surfactant. The proposed pretreatment method allows for the batch pretreatment of samples without pre-extraction using organic reagents, and almost no organic waste liquid is produced. Coupled with UPLC-FLD, an effective and accurate quantitative detection method for zearalenone is established. The recovery of spiked zearalenone in corn oils at different concentrations ranges from 85.7 to 89.0%, and the relative standard deviation is below 2.9%. The proposed pretreatment method overcomes the shortcomings of traditional pretreatment methods and has broad application prospects.

"Green" Extraction and On-Site Rapid Detection of Aflatoxin B1, Zearalenone and Deoxynivalenol in Corn, Rice and Peanut

The common mycotoxins in polluted grains are aflatoxin B1(AFB1), zearalenone (ZEN) and deoxynivalenol (DON). Because of the potential threat to humans and animals, it is necessary to detect mycotoxin contaminants rapidly. At present, later flow immunoassay (LFIA) is one of the most frequently used methods for rapid analysis. However, multistep sample pretreatment processes and organic solvents are also required to extract mycotoxins from grains. In this study, we developed a one-step and "green" sample pretreatment method without using organic solvents. By combining with LFIA test strips and a handheld detection device, an on-site method for the rapid detection of AFB1, ZEN and DON was developed. The LODs for AFB1, ZEN and DON in corn are 0.90 μg/kg, 7.11 μg/kg and 10.6 μg/kg, respectively, and the working ranges are from 1.25 μg/kg to 40 μg/kg, 20 μg/kg to 2000 μg/kg and 35 μg/kg to 1500 μg/kg, respectively. This method has been successfully applied to the detection of AFB1, ZEN and DON in corn, rice and peanut, with recoveries of 89 ± 3%-106 ± 3%, 86 ± 2%-108 ± 7% and 90 ± 2%-106 ± 10%, respectively. The detection results for the AFB1, ZEN and DON residues in certified reference materials by this method were in good agreement with their certificate values.

Determination of Zearalenone and Its Derivatives in Feed by Gas Chromatography-Mass Spectrometry with Immunoaffinity Column Cleanup and Isotope Dilution

In this study, a gas chromatography-mass spectrometry (GC-MS) method was established for the determination of zearalenone and its five derivatives in feed, including zearalanone, α-zearalanol, β-zearalanol, α-zearalenol, and β-zearalenol. An effective immunoaffinity column was prepared for sample purification, which was followed by the silane derivatization of the eluate after an immunoaffinity chromatography analysis for target compounds by GC-MS. Matrix effects were corrected by an isotope internal standard of zearalenone in this method. The six analytes had a good linear relationship in the range of 2-500 ng/mL, and the correlation coefficients were all greater than 0.99. The limits of detection (LODs) and limits of quantification (LOQs) were less than 1.5 μg/kg and 5.0 μg/kg, respectively. The average spike recoveries for the six feed matrices ranged from 89.6% to 112.3% with relative standard deviations (RSDs) less than 12.6%. Twenty actual feed samples were analyzed using the established method, and at least one target was detected. The established GC-MS method was proven to be reliable and suitable for the determination of zearalenone and its derivatives in feed.

Surface Plasmon Resonance (SPR) biosensor for detection of mycotoxins: A review

Mycotoxin is one of the most important natural pollutants, which poses a global threat to food safety. However, the pollution of mold in food production is inevitable. The detection technology of mycotoxins in food production is an important means to prevent the damage of mycotoxins, so rapid detection and screening to avoid pollution diffusion is essential. The focus of this review is to update the literature on the detection of mycotoxins by surface plasmon resonance (SPR) technology, rather than just traditional chromatographic methods. As a relatively novel and simple analytical method, SPR has been proved to be fast, sensitive and label-free, and has been widely used in real-time qualitative and quantitative analysis of various pollutants. This paper aims to give a broad overview of the sensors for detection and analysis of several common mycotoxins.

Development of a Hydrazine-Based Solid-Phase Extraction and Clean-Up Method for Highly Selective Quantification of Zearalenone in Edible Vegetable Oils by HPLC-FLD

Rapid, cost-efficient, and eco-friendly methods are desired today for routine analysis of the Fusarium mycotoxin zearalenone (ZEN) in edible vegetable oils. Liquid chromatography with fluorescence detection (HPLC-FLD) is commonly used to reliably control the specified ZEN maximum levels, which requires efficient sample clean-up to avoid matrix interferences. Therefore, a highly selective extraction and clean-up method based on reversible covalent hydrazine chemistry (RCHC) using hydrazine-functionalized silica was developed. This efficient solid-phase extraction (SPE) involves reversible hydrazone formation of ZEN with the hydrazine moiety covalently bound to a solid phase. Optimal conditions were achieved with 1 mL SPE cartridges filled with 400 mg of hydrazine-functionalized silica. The developed RCHC-SPE method was validated in an interlaboratory comparison study (ILC) with twelve participants analyzing six edible vegetable oils with a focus on maize oils. The derived method parameters (ZEN recovery 83%, repeatability 7.0%, and reproducibility 18%) meet the performance criteria of Commission Regulation (EC) No 401/2006. The developed RCHC-SPE-based HPLC-FLD method allows the reliable quantification of ZEN in the range of 47–494 µg/kg for different types of edible vegetable oils, also for matrix-reach native oils. Due to the high efficiency, the significantly reduced matrix load helps to extend the lifetime of analytical equipment. Furthermore, the re-useability of the RCHC-SPE cartridges contributes to an eco-friendly approach and reduced analysis costs. To our knowledge, this is the first report on ZEN quantification in edible vegetable oils based on manual RCHC-SPE cartridges. Due to its high performance, the developed RCHC-SPE method is a promising alternative to the current European standard method EN 16924:2017 (HPLC-FLD part).

Highly sensitive and convenient aptasensor based on Au NPs@Ce-TpBpy COF for quantitative determination of zearalenone

In this work, an aptasensor based on a portable U-disk electrochemical workstation in combination with a screen-printed electrode (SPE) is demonstrated for the quantitative determination of zearalenone (ZEN). The aptamer is immobilized on Au NPs@Ce-TpBpy COF (Covalent organic frameworks), which is modified on the surface of glassy carbon electrode. ZEN specifically binds to ZEN aptamer, which hinders the electron transfer and decreases the catalytic current of Au NPs@Ce-TpBpy COF for the reduction of hydrogen peroxide, measured by chronoamperometry (i-t). The quantitative detection of ZEN toxin is realized by a decrease of the catalytic current (ΔI). Under the optimal experimental conditions, the aptamer sensor exhibited excellent sensitivity, selectivity, reproducibility. A wide linear range of 1 pg mL^-1-10.0 ng mL^-1 with a detection limit of 0.389 pg mL^-1 (at 3σ) was obtained. The linear equation is ΔI = 0.401 lg c + 1.948 with a correlation coefficient of 0.9906. The recovery is in the range of 93.0-104.7% for the cornflour samples. The proposed method offers a new strategy for the rapid, inexpensive, and real-time detection of ZEN.

Development of a label-free plasmonic gold nanoparticles aggregates sensor on the basis of charge neutralization for the detection of zearalenone

Mycotoxin contamination of corn has been considered a serious problem because it can accumulate in different organs or tissues via ingestion or skin contact and cause several health problems in humans. We have constructed a label-free, colorimetric, and fluorescence dual-channel sensing platform for the detection of zearalenone. Here, we demonstrate that plasmonic gold nanoparticles aggregates could be rapidly formed on the basis of charge neutralization by positively charged SYBR Green I. The sensing platform allowed quantitative detection as low as 0.89 μg kg^-1 and visual detection as low as 2.5 μg kg^-1. The charge neutralization strategy eliminates a major source of instability in conventional gold nanoparticles colorimetric measurements and paves the way for accurate, label-free bioanalysis.