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Special Issue "Advanced Methods for Mycotoxins Detection"

A special issue of Toxins (ISSN 2072-6651). This special issue belongs to the section "Mycotoxins".

Deadline for manuscript submissions: 31 August 2019

Special Issue Editor

Guest Editor
Prof. Laura Anfossi

Universita degli Studi di Torino, Department of Chemistry, Torino, Italy
Website | E-Mail
Fax: +39-011-670-5242
Interests: analytical Chemistry; immunochemical assays

Special Issue Information

Dear Colleagues,

Advances in knowledge on fungal toxins and their toxicity are bringing to light new threats, but also new opportunities for the development of analytical methods for their detection.

On the one hand, the requirement of assuring food safety along the production chain and controlling trading commodities in an even-more-globalized world demands sensitive, rapid, cheap and easy-to-operate analytical tools to permit diffuse actions and continuous monitoring of these hazardous compounds.

Parallel to innovative approaches to expedite mycotoxin determination, the development of advanced instrumental techniques is highly urgent to address new concerns, such as: detecting co-occurring mycotoxins and investigating potentially-synergistic effects; identifying new emerging mycotoxins; and unveiling masked mycotoxins (i.e., modified compounds produced by plant and animal metabolism).  

The number and variety of samples involved in mycotoxin contamination is growing day-by-day, requiring the adaptation of analytical methods and especially developing appropriate extraction protocols. Extraction and detection of mycotoxins should begin to incorporate green chemistry principles.

This Special Issue will cover advances in assay design, extraction protocols, and innovative detection strategies with an emphasis on multi-target methods and methods to detect mycotoxins in non-conventional samples (e.g., non-regulated commodities) and will provide an overview of the usefulness of advanced analytical tools for gaining insights into mycotoxin occurrence and diffusion.

Dr. Laura Anfossi
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a double-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Toxins is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • multiplexing detection
  • QuECheRs extraction
  • masked mycotoxins
  • hidden mycotoxins
  • emerging mycotoxins
  • survey on mycotoxin occurrence
  • rapid methods
  • on field analysis
  • biosensors
  • LC-MS/MS
  • method validation
  • LFIA
  • aptamers
  • non-targeted analysis

Published Papers (10 papers)

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Research

Open AccessArticle Rapid Determination of Ochratoxin A in Grape and Its Commodities Based on a Label-Free Impedimetric Aptasensor Constructed by Layer-by-Layer Self-Assembly
Received: 1 January 2019 / Revised: 22 January 2019 / Accepted: 22 January 2019 / Published: 28 January 2019
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Abstract
A simple and sensitive label-free impedimetric aptasensor for rapid determination of ochratoxin A (OTA) has been developed, which was based on the combination between thiolated aptamer and gold nanoparticles by layer-by-layer self-assembly. Because of the interaction between aptamer and OTA, the relative normalized [...] Read more.
A simple and sensitive label-free impedimetric aptasensor for rapid determination of ochratoxin A (OTA) has been developed, which was based on the combination between thiolated aptamer and gold nanoparticles by layer-by-layer self-assembly. Because of the interaction between aptamer and OTA, the relative normalized electron-transfer resistance (ΔRct) values obtained by electrochemical impedance spectroscopy (EIS) was proportional to the concentration of OTA and showed a good linear relationship from 0.1 to 10.0 ng/mL, with a lower detection limit (0.030 ng/mL) than one-step thiolated DNA aptasensor. The established method was successfully applied to detect and analyze OTA in table wine and grape juice, and the recovery was 90.56%–104.21% when PVP effective removed of phenolic substances. The label-free impedimetric aptasensor was used for rapid detection and quantitation of OTA in the inoculated grapes with the Aspergillus Nigri (H1), and the production of OTA (62.4 μg/kg, 20 μg/kg) far exceeded the maximum levels of 2 μg/kg after inoculation for three days. The developed method exhibited a good specificity, high sensitivity, time-efficient, and it could be applied to detect the OTA concentration in grape and its commodities. Full article
(This article belongs to the Special Issue Advanced Methods for Mycotoxins Detection)
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Open AccessArticle Aptamer-Based Fluorometric Ochratoxin A Assay Based on Photoinduced Electron Transfer
Received: 20 January 2019 / Accepted: 22 January 2019 / Published: 24 January 2019
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Abstract
This study describes a novel quencher-free fluorescent method for ochratoxin A (OTA) detection based on the photoinduced electron transfer (PIET) between guanine and fluorophore. In the absence of OTA, carboxyfluorescein (FAM)-labeled aptamer can partly hybridize with the complementary strand of OTA aptamer (OTA-cAPT), [...] Read more.
This study describes a novel quencher-free fluorescent method for ochratoxin A (OTA) detection based on the photoinduced electron transfer (PIET) between guanine and fluorophore. In the absence of OTA, carboxyfluorescein (FAM)-labeled aptamer can partly hybridize with the complementary strand of OTA aptamer (OTA-cAPT), which contains four guanines at its 3′-end. As a result, the fluorescence of FAM is quenched due to PIET and stacked guanines. In the presence of OTA, FAM-labeled OTA aptamer can bind specifically to OTA, and thereby the high fluorescence intensity of the dye can be maintained. Under the optimal conditions, the method had a detection limit of 1.3 nM. In addition, the method we proposed is highly sensitive and specific for OTA. Furthermore, the method was proven to be reliable based on its successful application in the detection of OTA in red wine samples. Therefore, this promising, facile, and quencher-free method may be applied to detect other toxins by using other appropriate aptamers. Full article
(This article belongs to the Special Issue Advanced Methods for Mycotoxins Detection)
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Open AccessArticle Simultaneous Lateral Flow Immunoassay for Multi-Class Chemical Contaminants in Maize and Peanut with One-Stop Sample Preparation
Received: 26 December 2018 / Revised: 17 January 2019 / Accepted: 17 January 2019 / Published: 20 January 2019
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Abstract
Multi-class chemical contaminants, such as pesticides and mycotoxins, are recognized as the major risk factors in agro products. It is thus necessary to develop rapid and simple sensing methods to fulfill the on-site monitoring of multi-class chemical contaminants with different physicochemical properties. Herein, [...] Read more.
Multi-class chemical contaminants, such as pesticides and mycotoxins, are recognized as the major risk factors in agro products. It is thus necessary to develop rapid and simple sensing methods to fulfill the on-site monitoring of multi-class chemical contaminants with different physicochemical properties. Herein, a lateral flow immunoassay via time-resolved fluorescence was developed for the rapid, on-site, simultaneous, and quantitative sensing aflatoxin B1 (AFB1), zearalenone (ZEA), and chlorothalonil (CTN) in maize and peanut. The sample preparation was optimized to a single step, combining the grinding and extraction. Under optimal conditions, the sensing method lowered the limits of detection (LOD) to 0.16, 0.52, and 1.21 µg/kg in maize and 0.18, 0.57, and 1.47 µg/kg in peanut with an analytical range of 0.48–20, 1.56–200, and 3.63–300 µg/kg for AFB1, ZEA and CTN, respectively. The protocol could be completed within 15 min, including sample preparation and lateral flow immunoassay. The recovery range was 83.24–110.80%. An excellent correlation was observed between this approach and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for mycotoxins and gas chromatography-tandem mass spectrometry (GC-MS/MS) for pesticide in maize and peanut. This work could be applied in on-site multi-class sensing for food safety. Full article
(This article belongs to the Special Issue Advanced Methods for Mycotoxins Detection)
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Open AccessArticle Development of Indirect Competitive Enzyme-Linked Immunosorbent Assay to Detect Fusarium verticillioides in Poultry Feed Samples
Received: 14 December 2018 / Revised: 10 January 2019 / Accepted: 11 January 2019 / Published: 17 January 2019
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Abstract
Fumonisins are a group of toxic secondary metabolites that are produced by Fusarium verticillioides which are associated with poultry health hazard and great economic losses. The objective of the present study was to develop an immunological method to detect F. verticillioides in poultry [...] Read more.
Fumonisins are a group of toxic secondary metabolites that are produced by Fusarium verticillioides which are associated with poultry health hazard and great economic losses. The objective of the present study was to develop an immunological method to detect F. verticillioides in poultry feed samples. An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on a polyclonal antibody against 67 kDa protein of the F. verticillioides 97K exoantigen was developed to detect this fungus. Antibody anti-67 kDa protein showed cross-reactivity against F. graminearum (2–7%) and F. sporotrichioides (10%), but no or low cross-reactivity against Aspergillus sp. and Penicillium sp. exoantigens. The detection limit for the 67 kDa protein of F. verticillioides was 29 ng/mL. Eighty-one poultry feed samples were analyzed for Fusarium sp. count, 67 kDa protein of F. verticillioides and fumonisin concentrations. Eighty of the 81 feed samples (98.6%) showed Fusarium sp. contamination (mean 6.2 x 104 CFU/g). Mean 67 kDa protein and fumonisin concentration in the poultry feed samples was 21.0 µg/g and 1.02 µg/g, respectively. The concentration of 67 kDa protein, as determined by ic-ELISA correlated positively (p < 0.05) with fumonisin levels (r = 0.76). These results suggest that this ic-ELISA has potential to detect F. verticillioides and predict fumonisin contamination in poultry feed samples. Full article
(This article belongs to the Special Issue Advanced Methods for Mycotoxins Detection)
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Open AccessArticle Survey of Deoxynivalenol Contamination in Agricultural Products in the Chinese Market Using An ELISA Kit
Received: 12 November 2018 / Revised: 16 December 2018 / Accepted: 21 December 2018 / Published: 24 December 2018
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Abstract
A total of 328 agricultural product samples highly suspected to be contaminated, from flour companies, feed companies, and livestock farms throughout China, were surveyed for deoxynivalenol (DON) contamination using a self-assembly enzyme-linked immunosorbent assay (ELISA) kit. An ELISA kit for DON was developed [...] Read more.
A total of 328 agricultural product samples highly suspected to be contaminated, from flour companies, feed companies, and livestock farms throughout China, were surveyed for deoxynivalenol (DON) contamination using a self-assembly enzyme-linked immunosorbent assay (ELISA) kit. An ELISA kit for DON was developed with a 4.9 ng mL−1 limit of detection (LOD) in working buffer and a 200 ng g−1 LOD in authentic samples. The DON contamination detection rate was 88.7%, concentrations ranged from 200.9 to 6480.6 ng g−1, and the highest DON contamination was found in distillers’ dried grains with solubles with an average of 3204.5 ng g−1. Wheat bran and wheat were found to be the most commonly contaminated samples, and the corn meal samples had the lowest average DON level. This ELISA kit is a powerful alternative method for the rapid, sensitive, specific, accurate, and high-throughput determination of DON and can meet the maximum requirement levels. This survey suggests that DON contamination in the Chinese market is serious, and the contamination risk deserves attention. Essential preventive measures should be implemented to ensure food safety and human health. Full article
(This article belongs to the Special Issue Advanced Methods for Mycotoxins Detection)
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Open AccessArticle Carbon Quantum Dots Encapsulated Molecularly Imprinted Fluorescence Quenching Particles for Sensitive Detection of Zearalenone in Corn Sample
Toxins 2018, 10(11), 438; https://doi.org/10.3390/toxins10110438
Received: 1 October 2018 / Revised: 24 October 2018 / Accepted: 26 October 2018 / Published: 28 October 2018
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Abstract
An eco-friendly and efficient one-step approach for the synthesis of carbon quantum dots (CDs) that encapsulated molecularly imprinted fluorescence quenching particles (MIFQP) and their application for the determination of zearalenone (ZEA) in a cereal sample are described in this study. CDs with high [...] Read more.
An eco-friendly and efficient one-step approach for the synthesis of carbon quantum dots (CDs) that encapsulated molecularly imprinted fluorescence quenching particles (MIFQP) and their application for the determination of zearalenone (ZEA) in a cereal sample are described in this study. CDs with high luminescence were first synthesized, and then encapsulated in the silica-based matrix through a non-hydrolytic sol-gel process. The resulting ZEA-imprinted particles exhibited not only an excellent specific molecular recognition of ZEA, but also good photostability and obvious template binding-induced fluorescence quenching. Under the optimized conditions, the fluorescence intensity of MIFQP was inversely proportional to the concentration of ZEA. By validation, the detection range of these fluorescence quenching materials for ZEA was between 0.02 and 1.0 mg L−1, and the detection limit was 0.02 mg L−1 (S/N = 3). Finally, the MIFQP sensor was successfully applied for ZEA determination in corn with recoveries from 78% to 105% and the relative standard deviation (RSD %) was lower than 20%, which suggests its potential in actual applications. Full article
(This article belongs to the Special Issue Advanced Methods for Mycotoxins Detection)
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Open AccessArticle Multi-Occurrence of Twenty Mycotoxinsin Pasta and a Risk Assessment in the Moroccan Population
Toxins 2018, 10(11), 432; https://doi.org/10.3390/toxins10110432
Received: 30 September 2018 / Revised: 20 October 2018 / Accepted: 23 October 2018 / Published: 26 October 2018
Cited by 1 | PDF Full-text (628 KB) | HTML Full-text | XML Full-text
Abstract
In the present study, the multi-occurrence of twenty (20) mycotoxins in pasta samples consumed in Morocco was assessed. For this, a modified Quick, Easy, Cheap Effective, Rugged, and Safe method was validated. The mycotoxins studied were identified and quantified [...] Read more.
In the present study, the multi-occurrence of twenty (20) mycotoxins in pasta samples consumed in Morocco was assessed. For this, a modified Quick, Easy, Cheap Effective, Rugged, and Safe method was validated. The mycotoxins studied were identified and quantified by liquid chromatography–tandem mass spectrometry (LC–MS/MS) and gas chromatography–tandem mass spectrometry (GC-MS/MS). The validated method was applied to one hundred and six (n = 106) pasta samples purchased from several areas in the country. The analytical results showed that 99 out of 106 total samples (93.4%) were contaminated with at least one mycotoxin. Nine mycotoxins (Aflatoxin B1, Enniatin B, Enniatin B1, Enniatin A1, Zearalenone, Deoxynivalenol, 3-Acetyl-Deoxynivalenol, T-2, and HT-2 toxins) were present in the pasta samples. Enniatin B and Enniatin B1 were the predominant mycotoxins. The Zearalenone, Deoxynivalenol, HT-2, and T-2 toxins were present in 51.8%, 43.5%, 34.9%, and 16% of samples, respectively. Aflatoxin B1 was detected in only 2 samples. Risk exposure assessment concluded that mycotoxin levels found in pasta do not pose a significant human health risk for the Moroccan population. This is the first paper drafted on the multi-occurrence of mycotoxins in pasta from this country. Full article
(This article belongs to the Special Issue Advanced Methods for Mycotoxins Detection)
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Open AccessArticle Multiwalled Carbon Nanotube for One-Step Cleanup of 21 Mycotoxins in Corn and Wheat Prior to Ultraperformance Liquid Chromatography–Tandem Mass Spectrometry Analysis
Toxins 2018, 10(10), 409; https://doi.org/10.3390/toxins10100409
Received: 28 August 2018 / Revised: 28 September 2018 / Accepted: 2 October 2018 / Published: 10 October 2018
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Abstract
One-step solid-phase extraction (SPE) using a multiwalled carbon nanotube (MWCNT) for simultaneous analysis of 21 mycotoxins, including nine trichothecenes, zearalenone (ZEN) and its derivatives, four aflatoxins, and two ochratoxins, in corn and wheat was developed. Several key parameters affecting the performance of the [...] Read more.
One-step solid-phase extraction (SPE) using a multiwalled carbon nanotube (MWCNT) for simultaneous analysis of 21 mycotoxins, including nine trichothecenes, zearalenone (ZEN) and its derivatives, four aflatoxins, and two ochratoxins, in corn and wheat was developed. Several key parameters affecting the performance of the one-step SPE procedure—types of MWCNT, combinations with five sorbents (octadecylsilyl (C18), hydrophilic–lipophilic balance (HLB), mixed-mode cationic exchange (MCX), silica gel, and amino-propyl (NH2)), and filling amounts of the MWCNTs—were thoroughly investigated. The combination of 20 mg carboxylic MWCNT and 200 mg C18 was proven to be the most effective, allowing the quantification of all analyzed mycotoxins in corn and wheat. Under the optimized cleanup procedure prior to ultraperformance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) analysis, the method was validated by analyzing samples spiked at the limit of quantification (LOQ), two-times LOQ, and 10-times LOQ. Satisfactory linearity (r2 ≥ 0.9910), high sensitivity (LOQ in different ranges of 0.5–25 μg L−1), good recovery (75.6–110.3%), and acceptable precision (relative standard deviation (RSD), 0.3–10.7%) were obtained. The applicability of the method was further confirmed using raw samples of corn and wheat. In conclusion, the established method was rapid, simple and reliable for simultaneous analysis of 21 mycotoxins in corn and wheat. Full article
(This article belongs to the Special Issue Advanced Methods for Mycotoxins Detection)
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Open AccessArticle Development of a Sensitive Enzyme-Linked Immunosorbent Assay and Rapid Gold Nanoparticle Immunochromatographic Strip for Detecting Citrinin in Monascus Fermented Food
Received: 12 August 2018 / Revised: 28 August 2018 / Accepted: 28 August 2018 / Published: 2 September 2018
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Abstract
Antibodies against citrinin (CTN) were generated from rabbits, which were injected with CTN-keyhole limpet hemocyanin (KLH). This work involved the development of a sensitive competitive direct enzyme-linked immunosorbent assay (cdELISA) and a rapid gold nanoparticle immunochromatographic strip (immunostrip) method for analyzing CTN in [...] Read more.
Antibodies against citrinin (CTN) were generated from rabbits, which were injected with CTN-keyhole limpet hemocyanin (KLH). This work involved the development of a sensitive competitive direct enzyme-linked immunosorbent assay (cdELISA) and a rapid gold nanoparticle immunochromatographic strip (immunostrip) method for analyzing CTN in Monascus-fermented food. CTN at a concentration of 5.0 ng/mL caused 50% inhibition (IC50) of CTN-horseradish peroxidase (CTN-HRP) binding to the antibodies in the cdELISA. The capable on-site detection of CTN was accomplished by a rapid antibody-gold nanoparticle immunostrip with a detection limit of 20 ng/mL and that was completed within 15 min. A close inspection of 19 Monascus-fermented foods by cdELISA confirmed that 14 were contaminated with citrinin at levels from 28.6–9454 ng/g. Further analysis with the immunostrip is consistent with those results obtained using cdELISA. Both means are sensitive enough for the rapid examination of CTN in Monascus-fermented food products. Full article
(This article belongs to the Special Issue Advanced Methods for Mycotoxins Detection)
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Open AccessArticle Feasibility of A Novel On-Site Detection Method for Aflatoxin in Maize Flour from Markets and Selected Households in Kampala, Uganda
Received: 12 July 2018 / Revised: 8 August 2018 / Accepted: 9 August 2018 / Published: 11 August 2018
Cited by 1 | PDF Full-text (2285 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In sub-Saharan Africa, there is a high demand for affordable and accessible methods for on-site detection of aflatoxins for appropriate food safety management. In this study, we validated an electrochemical immunosensor device by the on-site detection of 60 maize flour samples from six [...] Read more.
In sub-Saharan Africa, there is a high demand for affordable and accessible methods for on-site detection of aflatoxins for appropriate food safety management. In this study, we validated an electrochemical immunosensor device by the on-site detection of 60 maize flour samples from six markets and 72 samples from households in Kampala. The immunosensor was successfully validated with a linear range from 0.7 ± 0.1 to 11 ± 0.3 µg/kg and limit of detection (LOD) of 0.7 µg/kg. The maize flour samples from the markets had a mean total aflatoxin concentration of 7.6 ± 2.3 µg/kg with approximately 20% of the samples higher than 10 µg/kg, which is the maximum acceptable level in East Africa. Further down the distribution chain, at the household level, approximately 45% of the total number contained total aflatoxin levels higher than the acceptable limit. The on-site detection method correlated well with the established laboratory-based HPLC and ELISA-detection methods for aflatoxin B1 with the correlation coefficients of 0.94 and 0.98, respectively. This study shows the feasibility of a novel on-site detection method and articulates the severity of aflatoxin contamination in Uganda. Full article
(This article belongs to the Special Issue Advanced Methods for Mycotoxins Detection)
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